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Design of pipeline installation

D-Geo Pipeline

User Manual

D-G EO P IPELINE
Design of pipeline installation

User Manual

Version: 16.1
Revision: 00
9 February 2016

D-G EO P IPELINE, User Manual

Published and printed by:
Deltares
Boussinesqweg 1
2629 HV Delft
P.O. 177
2600 MH Delft
The Netherlands

For sales contact:
telephone: +31 88 335 81 88
fax:
+31 88 335 81 11
e-mail:
sales@deltaressystems.nl
www:
http://www.deltaressystems.nl

telephone:
fax:
e-mail:
www:

+31 88 335 82 73
+31 88 335 85 82
info@deltares.nl
https://www.deltares.nl

For support contact:
telephone: +31 88 335 81 00
fax:
+31 88 335 81 11
e-mail:
support@deltaressystems.nl
www:
http://www.deltaressystems.nl

Copyright © 2016 Deltares
All rights reserved. No part of this document may be reproduced in any form by print, photo
print, photo copy, microfilm or any other means, without written permission from the publisher:
Deltares.

Contents

Contents
1 General Information
1.1 Preface . . . . . . . . . . . . . . . . . . . .
1.2 Installation of pipelines . . . . . . . . . . . .
1.2.1 Horizontal Directional Drilling technique
1.2.2 Micro Tunneling . . . . . . . . . . . .
1.2.3 Installation in trench . . . . . . . . .
1.3 Features in standard module (HDD) . . . . . .
1.3.1 Soil profile . . . . . . . . . . . . . .
1.3.2 Pipeline materials . . . . . . . . . . .
1.3.3 Factors . . . . . . . . . . . . . . . .
1.3.4 Results . . . . . . . . . . . . . . . .
1.4 Features in additional modules . . . . . . . .
1.4.1 Micro Tunneling module . . . . . . .
1.4.2 Trenching module . . . . . . . . . . .
1.5 History . . . . . . . . . . . . . . . . . . . .
1.6 Minimum System Requirements . . . . . . .
1.7 Definitions and Symbols . . . . . . . . . . .
1.8 Getting Help . . . . . . . . . . . . . . . . .
1.9 Getting Support . . . . . . . . . . . . . . . .
1.10 Deltares . . . . . . . . . . . . . . . . . . .
1.11 Deltares Systems . . . . . . . . . . . . . . .
1.12 On-line software (Citrix) . . . . . . . . . . . .

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2 Getting Started
2.1 Starting D-G EO P IPELINE . . . . . .
2.2 Main window . . . . . . . . . . . .
2.2.1 The menu bar . . . . . . .
2.2.2 The icon bar . . . . . . . .
2.2.3 View Input . . . . . . . . .
2.2.4 Info bar . . . . . . . . . . .
2.2.5 Title panel . . . . . . . . .
2.2.6 Status bar . . . . . . . . .
2.3 Files . . . . . . . . . . . . . . . .
2.4 Tips and Tricks . . . . . . . . . . .
2.4.1 Keyboard shortcuts . . . . .
2.4.2 Exporting figures and reports
2.4.3 Copying part of a table . . .

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3 General
3.1 File menu . . . . . . . . . . . . . . .
3.1.1 General options . . . . . . . .
3.1.2 Option ”Export Results as csv”
3.2 Tools menu . . . . . . . . . . . . . .
3.2.1 Program Options - View . . .
3.2.2 Program Options - General . .
3.2.3 Program Options - Locations .
3.2.4 Program Options - Language .
3.2.5 Program Options - Modules . .
3.3 Help menu . . . . . . . . . . . . . .
3.3.1 Error Messages . . . . . . .
3.3.2 Manual . . . . . . . . . . . .
3.3.3 Deltares Systems Website . .

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D-G EO P IPELINE, User Manual

3.3.4
3.3.5

Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
About D-G EO P IPELINE . . . . . . . . . . . . . . . . . . . . . . . . 37

4 Input
4.1 Project menu . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.1 Model . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1.2 Project Properties . . . . . . . . . . . . . . . . . . . .
4.1.3 View Input File . . . . . . . . . . . . . . . . . . . . . .
4.2 Soil menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2.1 Materials – Standard . . . . . . . . . . . . . . . . . . .
4.2.2 Materials – Settlement Koppejan . . . . . . . . . . . . .
4.2.3 Materials – Settlement Isotache . . . . . . . . . . . . . .
4.2.4 Materials – Database . . . . . . . . . . . . . . . . . . .
4.3 Geometry menu . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.1 New . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.2 New Wizard . . . . . . . . . . . . . . . . . . . . . . .
4.3.3 Import . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.4 Import geometry from database . . . . . . . . . . . . . .
4.3.5 Export . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.6 Export as Plaxis/DOS . . . . . . . . . . . . . . . . . . .
4.3.7 Limits . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.8 Points . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.9 Import PL-line . . . . . . . . . . . . . . . . . . . . . .
4.3.10 PL-Lines . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.11 Phreatic Line . . . . . . . . . . . . . . . . . . . . . . .
4.3.12 Layers . . . . . . . . . . . . . . . . . . . . . . . . . .
4.3.13 PL-lines per Layer . . . . . . . . . . . . . . . . . . . .
4.3.14 Check Geometry . . . . . . . . . . . . . . . . . . . . .
4.4 GeoObjects menu . . . . . . . . . . . . . . . . . . . . . . . .
4.4.1 Boundaries Selection . . . . . . . . . . . . . . . . . . .
4.4.2 Calculation Verticals . . . . . . . . . . . . . . . . . . .
4.5 Loads menu . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.5.1 Traffic Loads . . . . . . . . . . . . . . . . . . . . . . .
4.6 Pipe menu . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.6.1 Pipeline Configuration . . . . . . . . . . . . . . . . . .
4.6.1.1 Pipeline Configuration for HDD . . . . . . . . .
4.6.1.2 Pipeline Configuration for Micro tunneling . . . .
4.6.1.3 Pipeline Configuration for Construction in trench
4.6.2 Product Pipe Material Data . . . . . . . . . . . . . . . .
4.6.2.1 Product Pipe Material Data for HDD . . . . . .
4.6.2.2 Product Pipe Material Data for Micro tunneling .
4.6.3 Engineering Data . . . . . . . . . . . . . . . . . . . . .
4.6.3.1 Engineering Data for HDD . . . . . . . . . . .
4.6.3.2 Engineering Data for Micro tunneling . . . . . .
4.6.3.3 Engineering Data for Construction in trench . .
4.6.4 Drilling Fluid Data . . . . . . . . . . . . . . . . . . . . .
4.7 Defaults menu . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.1 Factors . . . . . . . . . . . . . . . . . . . . . . . . . .
4.7.1.1 Factors for HDD . . . . . . . . . . . . . . . .
4.7.1.2 Factors for Micro tunneling . . . . . . . . . . .
4.7.1.3 Factors for Construction in trench . . . . . . . .
4.7.2 Special Stress Analysis . . . . . . . . . . . . . . . . . .
5 Calculations

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5.1
5.2
5.3

Start Calculation . . . . . . . . . . .
Special Stress Analysis (only for HDD)
Warning and Error messages . . . . .
5.3.1 Warning messages . . . . . .
5.3.2 Error messages . . . . . . .

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6 View Results
6.1 Report selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2 Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.1 Report – Drilling Fluid Pressure . . . . . . . . . . . . . . . . . . . .
6.2.1.1 Report – Drilling Fluid Data . . . . . . . . . . . . . . . . .
6.2.1.2 Report – Equilibrium between Drilling Fluid Pressure and
Pore Pressure . . . . . . . . . . . . . . . . . . . . . . .
6.2.2 Report – Settlements of soil layers below the pipeline . . . . . . . . .
6.2.3 Report – Subsidence . . . . . . . . . . . . . . . . . . . . . . . . .
6.2.4 Report – Soil Mechanical Data . . . . . . . . . . . . . . . . . . . .
6.2.4.1 Soil Mechanical Parameters for HDD . . . . . . . . . . . .
6.2.4.2 Soil Mechanical Parameters for Micro tunneling . . . . . . .
6.2.4.3 Soil Mechanical Parameters for Construction in trench . . .
6.2.5 Report – Data for Stress Analysis . . . . . . . . . . . . . . . . . . .
6.2.6 Report – Stress Analysis . . . . . . . . . . . . . . . . . . . . . . .
6.2.6.1 Stress Analysis HDD . . . . . . . . . . . . . . . . . . . .
6.2.7 Report – Operation Parameters (Trenching) . . . . . . . . . . . . . .
6.2.8 Report – Face Support Pressures and Thrust Forces (Micro tunneling)
6.3 Drilling Fluid Pressures Plots . . . . . . . . . . . . . . . . . . . . . . . . .
6.4 Operation Parameter Plots . . . . . . . . . . . . . . . . . . . . . . . . . .
6.4.1 Operation Parameter Plots for Micro Tunneling . . . . . . . . . . . .
6.4.2 Operation Parameter Plots for Construction in trench . . . . . . . . .
6.5 Stresses in Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.6 Subsidence Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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7 Graphical Geometry Input
7.1 Geometrical objects . . . . . . . . . . . .
7.1.1 Geometry elements . . . . . . . .
7.1.2 Construction elements . . . . . .
7.2 Assumptions and restrictions . . . . . . .
7.3 View Input Window . . . . . . . . . . . .
7.3.1 General . . . . . . . . . . . . . .
7.3.2 Buttons . . . . . . . . . . . . . .
7.3.3 Legend . . . . . . . . . . . . . .
7.4 Geometry modeling . . . . . . . . . . . .
7.4.1 Create a new geometry . . . . . .
7.4.2 Set limits . . . . . . . . . . . . .
7.4.3 Draw layout . . . . . . . . . . . .
7.4.4 Generate layers . . . . . . . . .
7.4.5 Add piezometric level lines . . . .
7.5 Graphical manipulation . . . . . . . . . .
7.5.1 Selection of elements . . . . . . .
7.5.2 Deletion of elements . . . . . . .
7.5.3 Using the right-hand mouse button
7.5.4 Dragging elements . . . . . . . .

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8 Tutorial 1: Calculation and assessment of the drilling fluid pressure
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8.1 Introduction to the case . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

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D-G EO P IPELINE, User Manual

8.2

Project . . . . . . . . . . .
8.2.1 Start . . . . . . . .
8.2.2 Project Properties .
8.2.3 Model . . . . . . .
8.3 Geometry . . . . . . . . . .
8.3.1 Soil layer properties
8.3.2 Phreatic Line . . . .
8.3.3 Layers . . . . . . .
8.3.4 PL-Lines per Layers
8.3.5 Check Geometry . .
8.4 Pipeline Configuration . . . .
8.5 Soil behavior . . . . . . . .
8.6 Calculation Verticals . . . .
8.7 Product Pipe Material Data .
8.8 Drilling Fluid Data . . . . . .
8.9 Factors . . . . . . . . . . .
8.10 Results . . . . . . . . . . .
8.11 Conclusion . . . . . . . . .

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9 Tutorial 2: Stress analysis of steel pipes and polyethylene pipes
9.1 Introduction to the case . . . . . . . . . . . . . . . . . . . .
9.2 Project Properties . . . . . . . . . . . . . . . . . . . . . . .
9.3 Product Pipe Material Data . . . . . . . . . . . . . . . . . .
9.4 Engineering Data . . . . . . . . . . . . . . . . . . . . . . .
9.5 Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.6 Calculation and Results (Tutorial-2a) . . . . . . . . . . . . .
9.6.1 Results of the pulling force calculation . . . . . . . .
9.6.2 Results of the pipe stress analysis of the steel pipe . .
9.7 Special Pipe Stress Analysis (Tutorial-2b) . . . . . . . . . . .
9.8 Polyethylene Product Pipe (Tutorial-2c) . . . . . . . . . . . .
9.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . .

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10 Tutorial 3: Influence of soil behavior on drilling fluid pressures
the pipe
10.1 Introduction to the case . . . . . . . . . . . . . . . . . . .
10.2 Geometry of the longitudinal cross section . . . . . . . . .
10.3 Soil layer properties . . . . . . . . . . . . . . . . . . . . .
10.4 Finishing the geometry of the longitudinal cross section . . .
10.5 Soil behavior . . . . . . . . . . . . . . . . . . . . . . . .
10.6 Calculated reduced soil load for pipe stress analysis . . . .
10.7 Calculated drilling fluid pressures . . . . . . . . . . . . . .
10.8 Drilling fluid pressure and groundwater pressure . . . . . .
10.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . .

and soil load on
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11 Tutorial 4: Exporting soil mechanical data for an extended stress analysis
11.1 Introduction to the case . . . . . . . . . . . . . . . . . . . . . . . . .
11.2 Settlement model . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11.3 Geometry of the longitudinal cross section . . . . . . . . . . . . . . .
11.4 Soil layer properties . . . . . . . . . . . . . . . . . . . . . . . . . . .
11.5 Finishing the geometry of the longitudinal cross section . . . . . . . . .
11.6 Calculated soil mechanical parameters in export file . . . . . . . . . . .
11.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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12 Tutorial 5: Drilling with a horizontal bending radius
179
12.1 Introduction to the case . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

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12.2 Pipeline Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
12.3 Calculation of the pulling force and pipe stress analysis . . . . . . . . . . . . 182
12.4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
13 Tutorial 6: Installation of bundled pipelines
13.1 Introduction to the case . . . . . . . . .
13.2 Product Pipe Material Data . . . . . . .
13.3 Drilling Fluid Data . . . . . . . . . . . .
13.4 Engineering Data . . . . . . . . . . . .
13.5 Factors . . . . . . . . . . . . . . . . .
13.6 Results . . . . . . . . . . . . . . . . .

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14 Tutorial 7: Face support pressure for micro tunneling
14.1 Introduction to the case . . . . . . . . . . . . . .
14.2 Model selection . . . . . . . . . . . . . . . . . .
14.3 Geometry . . . . . . . . . . . . . . . . . . . . .
14.3.1 Soil layer properties . . . . . . . . . . .
14.3.2 Phreatic Line . . . . . . . . . . . . . . .
14.3.3 Layers . . . . . . . . . . . . . . . . . .
14.3.4 PL-Lines per Layers . . . . . . . . . . .
14.3.5 Check Geometry . . . . . . . . . . . . .
14.4 Pipeline Configuration . . . . . . . . . . . . . . .
14.5 Pipe Material Data . . . . . . . . . . . . . . . .
14.6 Soil behavior . . . . . . . . . . . . . . . . . . .
14.7 Calculation Verticals . . . . . . . . . . . . . . .
14.8 Engineering Data . . . . . . . . . . . . . . . . .
14.9 Results: Operation Parameter Plots . . . . . . . .

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15 Tutorial 8: Uplift and thrust forces for micro tunneling
15.1 Introduction to the case . . . . . . . . . . . . . .
15.2 Geometry of the longitudinal cross section . . . .
15.3 Soil layer properties . . . . . . . . . . . . . . . .
15.4 Soil behavior . . . . . . . . . . . . . . . . . . .
15.5 Pipeline Configuration . . . . . . . . . . . . . . .
15.6 Calculation Verticals . . . . . . . . . . . . . . .
15.7 Engineering Data . . . . . . . . . . . . . . . . .
15.8 Results . . . . . . . . . . . . . . . . . . . . . .
15.8.1 Thrust Force . . . . . . . . . . . . . . .
15.8.2 Uplift safety . . . . . . . . . . . . . . . .

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16 Tutorial 9: Settlement and soil mechanical parameters for micro tunneling
16.1 Introduction to the case . . . . . . . . . . . . . . . . . . . . . . . . .
16.2 Settlement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.3 Geometry of the longitudinal cross section . . . . . . . . . . . . . . .
16.4 Soil layer properties . . . . . . . . . . . . . . . . . . . . . . . . . . .
16.5 Finishing the geometry of the longitudinal cross section . . . . . . . . .
16.6 Calculated soil mechanical parameters in export file . . . . . . . . . . .
16.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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17 Tutorial 10: Subsidence after micro tunneling
17.1 Introduction to the case . . . . . . . . . . . . .
17.1.1 Volume loss along the tunnel excavation
17.1.2 Modification of the drilling line . . . . . .
17.2 Pipeline Configuration . . . . . . . . . . . . . .
17.3 Material data . . . . . . . . . . . . . . . . . .

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17.4 Engineering Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
17.5 Results: Subsidence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
18 Tutorial 11: Installation of pipeline in a trench
18.1 Introduction to the case . . . . . . . . . . . . . . . .
18.2 Model . . . . . . . . . . . . . . . . . . . . . . . . .
18.3 Geometry of the longitudinal cross section . . . . . .
18.4 Soil layer properties . . . . . . . . . . . . . . . . . .
18.5 Finishing the geometry of the longitudinal cross section
18.5.1 Phreatic Line . . . . . . . . . . . . . . . . .
18.5.2 Layers . . . . . . . . . . . . . . . . . . . .
18.5.3 PL-Lines per Layer . . . . . . . . . . . . . .
18.6 Adding a waterway . . . . . . . . . . . . . . . . . .
18.7 Calculation Verticals . . . . . . . . . . . . . . . . .
18.8 Boundaries Selection . . . . . . . . . . . . . . . . .
18.9 Trench configuration and pipe material . . . . . . . .
18.10 Engineering Data . . . . . . . . . . . . . . . . . . .
18.11 Results: Soil Mechanical Parameters . . . . . . . . .

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19 Tutorial 12: Trenching: uplift and heave
19.1 Introduction to the case . . . . . . . . . . . . . . . . . . . . . . . . .
19.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.3 Phreatic level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.4 Calculation Verticals . . . . . . . . . . . . . . . . . . . . . . . . . .
19.5 Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.6 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.6.1 Uplift safety for trenching in Peat layer (Tutorial-12a) . . . . . .
19.6.2 Uplift safety for trenching in Soft Organic Clay layer (Tutorial-12b)
19.6.3 Hydraulic Heave Safety . . . . . . . . . . . . . . . . . . . . .
19.7 Lowering the hydraulic head (Tutorial-12c) . . . . . . . . . . . . . . .

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20 Design of a pipeline
20.1 Design of a pipeline crossing using the HDD technique . . . . .
20.1.1 Location of entry and exit points . . . . . . . . . . . .
20.1.2 Inclination at the entry and exit points . . . . . . . . . .
20.1.3 The limitations of the object to be crossed . . . . . . .
20.1.4 Determination of allowable curve radius . . . . . . . . .
20.1.5 Determination of combined bending radius . . . . . . .
20.2 Design of a pipeline crossing using the micro tunneling technique
20.3 Design of a pipeline using a trench . . . . . . . . . . . . . . .

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21 Calculation of soil mechanical data
21.1 Neutral vertical stress . . . . . . . . . . . . . . . . . . . . . . . . .
21.2 Passive vertical stress . . . . . . . . . . . . . . . . . . . . . . . .
21.3 Reduced neutral vertical stress . . . . . . . . . . . . . . . . . . . .
21.3.1 Reduced neutral vertical stress in compressible soil layers . .
21.3.2 Reduced neutral vertical stress in non-compressible soil layers
21.4 Initial vertical stress . . . . . . . . . . . . . . . . . . . . . . . . . .
21.5 Neutral horizontal stress . . . . . . . . . . . . . . . . . . . . . . .
21.5.1 Pipelines installed using the HDD technique . . . . . . . . .
21.5.2 Pipelines installed in a trench or using micro tunneling . . . .
21.6 Vertical modulus of subgrade reaction . . . . . . . . . . . . . . . . .
21.6.1 Pipelines installed using a drilling technique . . . . . . . . .
21.6.2 Pipelines installed in a trench . . . . . . . . . . . . . . . . .
21.7 Horizontal modulus of subgrade reaction . . . . . . . . . . . . . . .

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Contents

21.7.1 Pipelines installed using a drilling technique . . . . .
21.7.2 Pipelines installed in a trench . . . . . . . . . . . . .
21.8 Ultimate vertical bearing capacity . . . . . . . . . . . . . . .
21.9 Ultimate horizontal bearing capacity . . . . . . . . . . . . . .
21.9.1 Pipelines installed using the HDD technique . . . . .
21.9.2 Pipelines installed in a trench or using micro tunneling
21.10 Vertical displacement . . . . . . . . . . . . . . . . . . . . .
21.10.1 Isotache model . . . . . . . . . . . . . . . . . . . .
21.10.2 Koppejan model . . . . . . . . . . . . . . . . . . .
21.11 Maximal axial friction . . . . . . . . . . . . . . . . . . . . .
21.11.1 Pipelines installed using the HDD technique . . . . .
21.11.2 Pipelines installed in a trench or using micro tunneling
21.12 Displacement at maximal friction . . . . . . . . . . . . . . .
21.12.1 Pipelines installed using the HDD technique . . . . .
21.12.2 Pipelines installed in a trench or using micro tunneling
21.13 Global determination of the soil type . . . . . . . . . . . . .
21.14 Traffic load . . . . . . . . . . . . . . . . . . . . . . . . . .

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22 Drilling fluid pressures calculation
279
22.1 Minimum required drilling fluid pressure . . . . . . . . . . . . . . . . . . . . 279
22.1.1 Static pressure of the drilling fluid column p1 . . . . . . . . . . . . . 279
22.1.2 Excess pressure to maintain flow of drilling fluid p2 . . . . . . . . . . 280
22.1.3 Minimum drilling fluid pressure for Stage 1 (pilot pipe in the pilot hole) . 281
22.1.4 Minimum drilling fluid pressure for Stage 2 (drill pipe in the pre-ream
hole) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
22.1.5 Minimum drilling fluid pressure for Stage 3 (product pipe in the borehole)282
22.2 Maximum allowable drilling fluid pressure . . . . . . . . . . . . . . . . . . . 282
22.2.1 Maximum allowable drilling fluid pressure in undrained layers . . . . . 283
22.2.2 Maximum allowable drilling fluid pressure in drained layers . . . . . . 284
22.3 Equivalent diameter for a bundled pipeline . . . . . . . . . . . . . . . . . . 285
22.4 Equilibrium between drilling fluid pressure and pore pressure . . . . . . . . . 285
23 Strength pipeline calculation
23.1 Buoyancy control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23.2 Pulling force in a flexible pipeline . . . . . . . . . . . . . . . . . . . . . .
23.2.1 Roller-lane . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23.2.2 Straight part of the borehole . . . . . . . . . . . . . . . . . . . .
23.2.3 Curved part of the borehole . . . . . . . . . . . . . . . . . . . . .
23.2.4 Friction due to soil reaction in the curved part . . . . . . . . . . . .
23.2.5 Friction due to curved forces . . . . . . . . . . . . . . . . . . . .
23.3 Maximum representative pulling force . . . . . . . . . . . . . . . . . . . .
23.4 Pulling force for a bundled pipeline . . . . . . . . . . . . . . . . . . . . .
23.5 Strength calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23.5.1 Strength calculation for Load Combination 1A: start of the pullback
operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23.5.2 Strength calculation for Load Combination 1B: end of the pullback operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23.5.3 Strength calculation for Load Combination 2: application of internal
pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23.5.4 Strength calculation for Load Combination 3: pipeline in operation,
without internal pressure . . . . . . . . . . . . . . . . . . . . . .
23.5.5 Strength calculation for Load Combination 4: pipeline in operation,
with internal pressure . . . . . . . . . . . . . . . . . . . . . . . .
23.6 Check of calculated stresses . . . . . . . . . . . . . . . . . . . . . . . .

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23.6.1 Check of calculated stresses according to the Dutch standard NEN .
23.6.1.1 Check of calculated stresses acc. to the Dutch standard
NEN: Steel pipe . . . . . . . . . . . . . . . . . . . . .
23.6.1.2 Check of calculated stresses acc. to the Dutch standard
NEN: Polyethylene pipe . . . . . . . . . . . . . . . . .
23.7 Deflection of the pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23.8 Implosion of the polyethylene pipe . . . . . . . . . . . . . . . . . . . . .
23.8.1 Check on implosion during the pull-back operation . . . . . . . . .
23.8.2 Check on implosion when the pipe is in operation . . . . . . . . . .
24 Micro tunneling
24.1 Support pressures and thrust forces
24.1.1 Target support pressure . .
24.1.2 Minimal support pressure . .
24.1.3 Maximal support pressure .
24.1.4 Thrust force . . . . . . . .
24.2 Uplift Safety . . . . . . . . . . . . .
24.3 Subsidence . . . . . . . . . . . . .

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25 Trenching
311
25.1 Uplift Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
25.2 Bursting of the trench bottom (heaving) . . . . . . . . . . . . . . . . . . . . 312
26 Effective Stress and Pore Pressure
26.1 Hydraulic head from piezometric level lines . .
26.2 Phreatic line . . . . . . . . . . . . . . . . .
26.3 Stress by soil weight . . . . . . . . . . . . .
26.4 Distribution of stress by loading . . . . . . . .
26.4.1 Stress increment caused by a line load
26.4.2 Stress increment caused by a strip load
26.5 Effective stress and pore pressure . . . . . .

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27 Benchmarks

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Bibliography

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List of Figures

List of Figures
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.14

HDD / Pilot drilling (DCA-guidelines) . . . . . . . . . . . . . . . . . . .
HDD / Pre-reaming (DCA-guidelines) . . . . . . . . . . . . . . . . . . .
HDD / Pull back operation (DCA-guidelines) . . . . . . . . . . . . . . . .
Reamer and cutting wheel . . . . . . . . . . . . . . . . . . . . . . . .
Jacking frame and micro tunneling machine in the start shaft . . . . . . .
Pipeline installation in a trench . . . . . . . . . . . . . . . . . . . . . .
Face support pressures . . . . . . . . . . . . . . . . . . . . . . . . . .
Modelisation of the effect of arching . . . . . . . . . . . . . . . . . . . .
Pipeline installation in trench . . . . . . . . . . . . . . . . . . . . . . .
Compaction of the fill after pipeline installation . . . . . . . . . . . . . .
Co-ordinate system . . . . . . . . . . . . . . . . . . . . . . . . . . . .
‘Products’ menu of Deltares Systems website (www.deltaressystems.com)
Support window, Problem Description tab . . . . . . . . . . . . . . . . .
Send Support E-Mail window . . . . . . . . . . . . . . . . . . . . . . .

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18

2.1
2.2
2.3
2.4
2.5
2.6
2.7

Main Window . . . . . . . . . . . . . . . . . . . . . . .
D-G EO P IPELINE menu bar . . . . . . . . . . . . . . . .
D-G EO P IPELINE icon bar . . . . . . . . . . . . . . . . .
View Input window, Geometry tab . . . . . . . . . . . .
View Input window, Input tab . . . . . . . . . . . . . . .
View Input window, Top View tab . . . . . . . . . . . . .
Selection of different parts of a table using the arrow cursor

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22
23
24
24
28

3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9

New File window . . . . . . . . . . . .
3D configuration in SCIA Pipeline . . . .
Program Options window, View tab . . .
Program Options window, General tab .
Program Options window, Locations tab .
Program Options window, Language tab
Program Options window, Modules tab .
Error Messages window . . . . . . . .
About D-G EO P IPELINE window . . . .

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4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
4.14
4.15
4.16
4.17
4.18
4.19
4.20

Model window . . . . . . . . . . . . . . . . . . . . . . . . .
Project Properties window, Identification tab . . . . . . . . . .
Project Properties window, View Input tab . . . . . . . . . . .
Materials window, Parameters tab . . . . . . . . . . . . . . . .
Materials window, Parameters tab (Settlement acc. to Koppejan)
Materials window, Parameters tab (Settlement acc. to Isotache) .
Materials window, Database tab . . . . . . . . . . . . . . . .
New Wizard window (Basic Layout) . . . . . . . . . . . . . . .
New Wizard window (Top Layer Shape) . . . . . . . . . . . . .
New Wizard window (Top Layer Specification) . . . . . . . . .
New Wizard window (Material Types) . . . . . . . . . . . . . .
New Wizard window (Summary) . . . . . . . . . . . . . . . .
Geometry Limits window . . . . . . . . . . . . . . . . . . . .
Points window . . . . . . . . . . . . . . . . . . . . . . . . .
Confirm window for deleting used points . . . . . . . . . . . .
Options for Import of PL-line window . . . . . . . . . . . . . .
PL-Lines window . . . . . . . . . . . . . . . . . . . . . . . .
Phreatic Line window . . . . . . . . . . . . . . . . . . . . . .
Layers window, Boundaries tab . . . . . . . . . . . . . . . . .
Layers window, Materials tab . . . . . . . . . . . . . . . . . .

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4.21
4.22
4.23
4.24
4.25
4.26
4.27
4.28
4.29
4.30
4.31
4.32
4.33
4.34
4.35
4.36

4.46
4.47
4.48
4.49

PL-line per Layer window . . . . . . . . . . . . . . . . . . . . . . . . . . .
PL-lines and vertical pressure distribution . . . . . . . . . . . . . . . . . . .
Information window to confirm a valid geometry . . . . . . . . . . . . . . . .
Boundaries Selection window for (a) HDD/Micro-tunneling and (b) for Trenching
Calculation Verticals window . . . . . . . . . . . . . . . . . . . . . . . . .
Traffic Loads window . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipeline Configuration window (for HDD) . . . . . . . . . . . . . . . . . . .
Schematization of the pipeline (HDD) . . . . . . . . . . . . . . . . . . . . .
Pipeline Configuration window (for Micro tunneling) . . . . . . . . . . . . . .
Pipeline Configuration window (Construction in trench) . . . . . . . . . . . .
Product Pipe Material Data window (Steel) . . . . . . . . . . . . . . . . . .
Steel pipes library window . . . . . . . . . . . . . . . . . . . . . . . . . .
Product Pipe Material Data window (Polyethylene) . . . . . . . . . . . . . .
PE pipes library window . . . . . . . . . . . . . . . . . . . . . . . . . . .
Product Pipe Material Data window, Pipe material sub-window . . . . . . . .
Product Pipe Material Data window (Steel or Concrete pipe, Micro Tunneling
model) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Product Pipe Material Data window (Synthetic pipe, Micro tunneling model) . .
Engineering Data window (HDD) . . . . . . . . . . . . . . . . . . . . . . .
Definition of the bedding angle β and the load angle α . . . . . . . . . . . .
Engineering Data window (Micro tunneling) . . . . . . . . . . . . . . . . . .
Engineering Data window (Construction in trench) . . . . . . . . . . . . . .
Drilling Fluid Data window . . . . . . . . . . . . . . . . . . . . . . . . . . .
Factors window (HDD) for polyethylene pipe, acc. to the Dutch standard NEN .
Factors window (HDD) for steel pipe, acc. to the Dutch standard NEN . . . . .
Factors window (HDD) for polyethylene pipe, acc. to the European standard
CEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Factors window (HDD) for steel pipe, according to the European standard CEN
Factors window (Micro tunneling) . . . . . . . . . . . . . . . . . . . . . . .
Factors window (Construction in trench) . . . . . . . . . . . . . . . . . . . .
Special Stress Analysis window (HDD) . . . . . . . . . . . . . . . . . . . .

5.1
5.2

Warning window (before calculation) about allowable radius . . . . . . . . . . 88
Error Messages window . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

6.1
6.2
6.3

Report Selection window . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Report window, Drilling Fluid Data section . . . . . . . . . . . . . . . . . . 93
Report window, Equilibrium between Drilling Fluid Pressure and Pore Pressure section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Report window, Settlements of soil layers below the pipeline section . . . . . 95
Report window, Subsidence section . . . . . . . . . . . . . . . . . . . . . 96
Report window – Soil Mechanical Parameters section (for HDD) . . . . . . . 97
Report window – Soil Mechanical Parameters section (for Micro tunneling) . . 98
Report window – Soil Mechanical Parameters section (for Construction in trench) 99
Report window, Buoyancy Control section . . . . . . . . . . . . . . . . . . 100
Report window, Calculation pulling force section . . . . . . . . . . . . . . . 101
Locations of the characteristic points T1 to T6 . . . . . . . . . . . . . . . . . 102
Report window, Stress analysis for load combination 1A . . . . . . . . . . . 102
Report window, Stress analysis for load combination 1B . . . . . . . . . . . 103
Report window, Stress analysis for load combination 2 . . . . . . . . . . . . 103
Report window – Stress analysis for load combination 3 . . . . . . . . . . . 104
Report window, Stress analysis for load combination 4 . . . . . . . . . . . . 104
Report window, Check on calculated stresses section (steel pipe) . . . . . . . 105
Report window, Check on calculated stresses section (PE pipe) . . . . . . . 106

4.37
4.38
4.39
4.40
4.41
4.42
4.43
4.44
4.45

6.4
6.5
6.6
6.7
6.8
6.9
6.10
6.11
6.12
6.13
6.14
6.15
6.16
6.17
6.18

xii

57
58
58
59
60
61
62
63
64
65
66
67
68
69
69
70
70
71
73
73
74
75
77
79
81
82
82
83
84

Deltares

List of Figures

6.19
6.20
6.21
6.22
6.23
6.24
6.25
6.26
6.27
6.28
6.29
6.30
6.31

Report window, Check on deflection section . . . . . . . . . .
Report window, Check for implosion section . . . . . . . . . .
Report window, Uplift Check section . . . . . . . . . . . . . .
Report window, Hydraulic Heave Check section . . . . . . . .
Report window, Operation Parameters section for Micro tunneling
Drilling Fluid Pressures Plots window . . . . . . . . . . . . . .
Operation Parameter Plots window, Face support pressures tab .
Operation Parameter Plots window, Thrust pressures tab . . . .
Operation Parameter Plots window, Safety uplift tab . . . . . . .
Operation Parameter Plots window, Safety uplift tab . . . . . . .
Operation Parameter Plots window, Safety hydraulic heave tab .
Stresses in Geometry window . . . . . . . . . . . . . . . . .
Subsidence Profiles window . . . . . . . . . . . . . . . . . .

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106
106
107
107
108
109
110
111
112
112
113
113
114

7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
7.15
7.16
7.17
7.18
7.19
7.20
7.21
7.22
7.23
7.24

View Input window, Geometry tab . . . . . . . . . . . . . . . . . . . .
View Input window, Geometry tab (legend displayed as Layer Numbers) .
Legend, Context menu . . . . . . . . . . . . . . . . . . . . . . . . . .
View Input window, Geometry tab (legend displayed as Material Numbers)
View Input window, Geometry tab (legend displayed as Material Names) .
Legend, Context menu (for legend displayed as Materials) . . . . . . . .
Color window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
View Input window, Geometry tab . . . . . . . . . . . . . . . . . . . .
Right Limit window . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Representation of a polyline . . . . . . . . . . . . . . . . . . . . . . . .
Examples of configurations of (poly)lines . . . . . . . . . . . . . . . . .
Example of invalid point not connected to the left limit . . . . . . . . . . .
Selection accuracy as area around cursor . . . . . . . . . . . . . . . . .
Selection accuracy as area around cursor . . . . . . . . . . . . . . . . .
Example of deletion of a point . . . . . . . . . . . . . . . . . . . . . . .
Example of deletion of a geometry point . . . . . . . . . . . . . . . . .
Example of deletion of a line . . . . . . . . . . . . . . . . . . . . . . .
Pop-up menu for right-hand mouse menu (Select mode) . . . . . . . . .
Layer window (Property editor of a layer) . . . . . . . . . . . . . . . . .
Point window (Property editor of a point) . . . . . . . . . . . . . . . . .
Boundary window (Property editor of a polyline) . . . . . . . . . . . . .
Boundary window (Property editor of a line) . . . . . . . . . . . . . . . .
PL-line window (Property editor of a PL-line) . . . . . . . . . . . . . . .
Example of dragging of a point . . . . . . . . . . . . . . . . . . . . . .

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117
120
120
121
121
121
122
122
123
123
124
125
125
126
126
126
127
127
128
128
128
129
129
129

8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
8.13
8.14
8.15

Pipeline configuration for Tutorial 1 . . . . .
New File window . . . . . . . . . . . . . .
View Input window . . . . . . . . . . . . .
Project Properties window, Identification tab
Project Properties window, View input tab . .
Model window . . . . . . . . . . . . . . .
Left Limit window . . . . . . . . . . . . . .
View Input window, Geometry tab . . . . .
Materials window . . . . . . . . . . . . . .
Phreatic Line window . . . . . . . . . . . .
Layers window, Materials tab . . . . . . . .
PL-lines per Layers window . . . . . . . . .
Check Geometry window . . . . . . . . . .
Pipeline Configuration window . . . . . . .
View Input window, Input tab . . . . . . . .

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131
132
133
133
134
135
135
136
136
137
137
138
138
139
139

Deltares

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xiii

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xiv

8.16
8.17
8.18
8.19
8.20
8.21

Boundaries Selection window . . .
Calculation Verticals window . . .
Product Pipe Material Data window
Drilling Fluid Data window . . . . .
Factors window . . . . . . . . . .
Drilling Fluid Pressures window . .

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140
141
142
143
144
145

9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
9.10
9.11
9.12
9.13
9.14
9.15
9.16

Pipeline configuration for Tutorial 2 . . . . . . . . . . . . . . . . . . . . . . 147
Product Pipe Material Data window . . . . . . . . . . . . . . . . . . . . . . 150
Engineering Data window . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Bedding and load angles on the pipeline (according to Figure D.2 of NEN 3650-1)151
Factors window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Report window, Calculation pulling force (filling percentage = 22%) . . . . . . 153
Schematic overview of the characteristic points . . . . . . . . . . . . . . . . 153
Report window, Calculation pulling force (filling percentage = 0%) . . . . . . . 154
Report window, Results Stress Analysis (Tutorial-2a) . . . . . . . . . . . . . 154
Report window, Check on calculated stresses (Tutorial-2a) . . . . . . . . . . 155
Report window, Soil Mechanical Parameters (Tutorial-2a) . . . . . . . . . . . 156
Special Stress Analysis window . . . . . . . . . . . . . . . . . . . . . . . . 157
Report window, Check on calculated stresses (Tutorial-2b) . . . . . . . . . . 157
Product Pipe Material Data window (Tutorial-2c) . . . . . . . . . . . . . . . . 158
Report window, Check on calculated stresses (Tutorial-2c) . . . . . . . . . . 159
Report window, Check for Implosion (Tutorial-2c) . . . . . . . . . . . . . . . 159

10.1 Pipeline configuration for Tutorial 3 . . . . . . . . . . . . . . . . . . . . .
10.2 Arching around the borehole . . . . . . . . . . . . . . . . . . . . . . . .
10.3 View Input window, Geometry tab . . . . . . . . . . . . . . . . . . . . .
10.4 Materials window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.5 Phreatic Line window . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.6 Layers window, Materials tab . . . . . . . . . . . . . . . . . . . . . . . .
10.7 View Input window, Geometry tab . . . . . . . . . . . . . . . . . . . . .
10.8 PL-lines per Layer window . . . . . . . . . . . . . . . . . . . . . . . . .
10.9 Boundaries Selection window . . . . . . . . . . . . . . . . . . . . . . . .
10.10 The effect of arching with increasing depth (Meijers and De Kock, 1995) . .
10.11 Report window, Calculation Pulling Force . . . . . . . . . . . . . . . . . .
10.12 Drilling Fluid Pressures window . . . . . . . . . . . . . . . . . . . . . . .
10.13 Report window, Equilibrium between drilling fluid pressure and pore pressure

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161
162
163
164
164
165
165
166
167
167
168
169
170

11.1
11.2
11.3
11.4
11.5
11.6
11.7
11.8
11.9

Pipeline configuration for Tutorial 4 . . . .
Model window . . . . . . . . . . . . . .
Point window . . . . . . . . . . . . . . .
View Input window, Geometry tab . . . .
Materials window . . . . . . . . . . . . .
Layers window, Materials tab . . . . . . .
Program Options window, Locations tab . .
Report window, Settlements along pipeline
Content of the export file for Tutorial 4 . . .

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171
173
173
174
175
176
176
177
177

12.1
12.2
12.3
12.4
12.5
12.6

Pipeline configuration of Tutorial 5 . . . .
Pipeline Configuration window . . . . .
View Input window, Top View tab . . . .
View Input window, Input tab . . . . . .
Report window, Calculation Pulling Force
Report window, General Data . . . . . .

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180
181
181
182
182
183

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Deltares

List of Figures

13.1
13.2
13.3
13.4
13.5

Product Pipe Material Data window . . .
Drilling Fluid Data window . . . . . . . .
Engineering Data window . . . . . . . .
Factors window . . . . . . . . . . . . .
Report window, Calculation Pulling Force

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187
188
189
189
190

14.1 Pipeline configuration for Tutorial 7 . . . . . . . . . . . . . .
14.2 Model window . . . . . . . . . . . . . . . . . . . . . . . .
14.3 Project Properties window, View input tab . . . . . . . . . . .
14.4 Left Limit window . . . . . . . . . . . . . . . . . . . . . . .
14.5 View Input window, Geometry tab . . . . . . . . . . . . . .
14.6 Materials window . . . . . . . . . . . . . . . . . . . . . . .
14.7 Phreatic Line window . . . . . . . . . . . . . . . . . . . . .
14.8 Layers window, Materials tab . . . . . . . . . . . . . . . . .
14.9 PL-lines per Layers window . . . . . . . . . . . . . . . . . .
14.10 Check Geometry window . . . . . . . . . . . . . . . . . . .
14.11 Pipeline Configuration window . . . . . . . . . . . . . . . .
14.12 View Input window, Input tab . . . . . . . . . . . . . . . . .
14.13 Product Pipe Material Data window . . . . . . . . . . . . . .
14.14 Boundaries Selection window . . . . . . . . . . . . . . . . .
14.15 Calculation Verticals window . . . . . . . . . . . . . . . . .
14.16 Engineering Data window . . . . . . . . . . . . . . . . . . .
14.17 Schematization of stress condition for micro-tunneling . . . . .
14.18 Operation Parameter Plots window, Face support pressure tab

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191
193
193
194
194
195
195
196
196
197
197
198
198
199
200
200
201
202

15.1 Soil layers and pipeline configuration for Tutorial 8 . . . . . . . . . . . . . .
15.2 Co-ordinates of the lower boundary of the Peat layer (before enlarging the right
limit) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.3 Right Limit window . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.4 Materials window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15.5 Layers window, Materials tab . . . . . . . . . . . . . . . . . . . . . . . .
15.6 View Input window, Geometry tab . . . . . . . . . . . . . . . . . . . . .
15.7 Boundaries Selection window . . . . . . . . . . . . . . . . . . . . . . . .
15.8 Pipeline Configuration window . . . . . . . . . . . . . . . . . . . . . . .
15.9 Calculation Verticals window . . . . . . . . . . . . . . . . . . . . . . . .
15.10 Engineering Data window . . . . . . . . . . . . . . . . . . . . . . . . . .
15.11 Operation Parameter Plots window, Thrust Force tab . . . . . . . . . . . .
15.12 Operation Parameter Plots window, Safety uplift tab . . . . . . . . . . . . .
15.13 Report window, Uplift Factors section . . . . . . . . . . . . . . . . . . . .

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204
205
205
206
206
207
208
209
209
210
211
211

16.1 Soil layers and pipeline configuration for Tutorial 9 . . . . . .
16.2 Model window . . . . . . . . . . . . . . . . . . . . . . .
16.3 Points window . . . . . . . . . . . . . . . . . . . . . . .
16.4 View Input window, Geometry tab . . . . . . . . . . . . .
16.5 Materials window . . . . . . . . . . . . . . . . . . . . . .
16.6 Layers window, Materials tab . . . . . . . . . . . . . . . .
16.7 Program Options window, Locations tab . . . . . . . . . . .
16.8 Report window, Settlements of soil layers below the pipeline
16.9 Report window, Soil Mechanical Parameters . . . . . . . .
16.10 Content of the CSV export file for Tutorial 9 . . . . . . . . .

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213
215
216
216
217
218
218
219
220
220

17.1
17.2
17.3
17.4

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223
225
226
227

Deltares

Bore hole section . . . . . . . . .
Pipeline configuration of Tutorial 10
Pipeline Configuration window . .
View Input window, Top View tab .

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D-G EO P IPELINE, User Manual

17.5
17.6
17.7
17.8

View Input window, Input tab . . . . . .
Product Pipe Material Data window . . .
Engineering Data window . . . . . . . .
Subsidence Profiles window for vertical 1

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227
228
228
229

18.1 Geometry of Tutorial 11 . . . . . . . . . . . . . . . . . . . . .
18.2 Model window . . . . . . . . . . . . . . . . . . . . . . . . .
18.3 View Input window, Geometry tab . . . . . . . . . . . . . . .
18.4 Materials window . . . . . . . . . . . . . . . . . . . . . . . .
18.5 Phreatic Line window . . . . . . . . . . . . . . . . . . . . . .
18.6 Layers window, Materials tab . . . . . . . . . . . . . . . . . .
18.7 View Input window, Geometry tab . . . . . . . . . . . . . . .
18.8 PL-lines per Layer window . . . . . . . . . . . . . . . . . . .
18.9 View Input window, Geometry tab (steps for drawing a waterway)
18.10 Points window . . . . . . . . . . . . . . . . . . . . . . . . .
18.11 Calculation Verticals window . . . . . . . . . . . . . . . . . .
18.12 Boundaries Selection window . . . . . . . . . . . . . . . . . .
18.13 Pipeline Configuration window . . . . . . . . . . . . . . . . .
18.14 View Input window, Input tab . . . . . . . . . . . . . . . . . .
18.15 View Input window, Top View tab . . . . . . . . . . . . . . . .
18.16 Engineering Data window . . . . . . . . . . . . . . . . . . . .
18.17 Report window, Soil Mechanical Parameters section . . . . . .

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231
232
233
234
234
235
235
236
236
237
237
238
238
239
239
240
241

19.1 Pipeline configuration for Tutorial 12 . . . . . . . . . . . . . . . . . . . . .
19.2 Materials window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.3 Layers window, Materials tab . . . . . . . . . . . . . . . . . . . . . . . .
19.4 PL-Line 1 window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.5 PL-lines per Layer window . . . . . . . . . . . . . . . . . . . . . . . . .
19.6 Calculation Verticals window . . . . . . . . . . . . . . . . . . . . . . . .
19.7 View Input window, Input tab (Tutorial-12a) . . . . . . . . . . . . . . . . .
19.8 Factors window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19.9 Operation Parameter Plots window, Safety uplift tab (Tutorial-12a) . . . . .
19.10 Report window, Uplift Factors section (Tutorial-12a) . . . . . . . . . . . . .
19.11 Layers window, Materials tab (Tutorial-12b) . . . . . . . . . . . . . . . . .
19.12 Report window, Uplift Factors section (Tutorial-12b) . . . . . . . . . . . . .
19.13 Operation Parameter Plots window, Safety hydraulic heave tab (Tutorial-12b)
19.14 Report window, Hydraulic heave of the trench bottom section (Tutorial-12b) .
19.15 View Input window, Geometry tab (Tutorial 12c) . . . . . . . . . . . . . . .
19.16 Points window (Tutorial 12c) . . . . . . . . . . . . . . . . . . . . . . . .
19.17 Operation Parameter Plots windows, Safety hydraulic heave tab (Tutorial 12c)
19.18 Report windows, Hydraulic heave of the trench bottom section (Tutorial 12c)

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243
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245
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247
248
248
249
249
250
251
251
252
252
253
253

20.1 Launch and reception shafts of the micro tunneling machine

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21.1 Schematic diagram for calculation of the neutral vertical stress . . . . . . . . 259
21.2 Schematic diagram for the definition of parameters H1 , H2 , γunsat and γsat
(Figure C.5 of NEN 3650-1) . . . . . . . . . . . . . . . . . . . . . . . . . . 260
21.3 The mobilization of the angle of internal friction in the development of the arching mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261
21.4 Definitions of H , h and hh . . . . . . . . . . . . . . . . . . . . . . . . . . 262
21.5 Schematic diagram of H and hp . . . . . . . . . . . . . . . . . . . . . . . 263
21.6 Pipe soil interaction modeled by springs . . . . . . . . . . . . . . . . . . . . 265
21.7 Values Kq and Kc according to Brinch Hansen (Figure C.14 of the NEN 3650-1)269
21.8 Creep Isotache pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
21.9 Influence of the tshift = tr parameter on the creep tail . . . . . . . . . . . . . 271

xvi

Deltares

List of Figures

21.10 Koppejan settlement . . . . . . . . . . . . . . . .
21.11 Schematization of the forces acting on the pipe . . .
21.12 Traffic load as a function of the depth and the pipe
models, according to NEN 3650-1 . . . . . . . . . .

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diameter,
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for
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both load
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22.1 Schematization of h1 and h2 . . . . . . . . . . . . . . . . . . . . . . . . . 284
23.1 Schematization of the buoyancy control . . . . . . . . . . . . . . . . . . . . 287
24.1 Upper and lower bound for the stability ratio N (Davis et al., 1980) . . . . . . 304
24.2 Values for KA3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305
24.3 Active soil wedge with soil column (Broere, 1994) . . . . . . . . . . . . . . . 306
25.1 Definition of parameters Hd , d1;d and d2;d (Figure 18 of NEN 6740:2006) . . . 313
25.2 Factor f for the contribution of the layers above the bottom of the excavation
(Figure 19 of NEN 6740:2006) . . . . . . . . . . . . . . . . . . . . . . . . 313
26.1 Pore pressure as a result of piezometric level lines . . . . . . . . . . . . . . 315
26.2 Stress distribution under a load column . . . . . . . . . . . . . . . . . . . . 316
26.3 Stress distribution under a load column . . . . . . . . . . . . . . . . . . . . 317

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Deltares

List of Tables

List of Tables
2.5

Keyboard shortcuts for D-G EO P IPELINE . . . . . . . . . . . . . . . . . . . 27

4.10 Unsaturated and saturated weight of the predefined materials . . . . . . . . . 49
8.1
8.2

Properties of the silty sand layer (Tutorial 1) . . . . . . . . . . . . . . . . . . 132
Properties of steel material (Tutorial 1) . . . . . . . . . . . . . . . . . . . . 132

9.1

Pipe properties (Tutorial 2) . . . . . . . . . . . . . . . . . . . . . . . . . . 148

10.1 Layer properties (Tutorial 3) . . . . . . . . . . . . . . . . . . . . . . . . . . 162
11.1 Settlement parameters (acc. Koppejan) of the soil layers (Tutorial 4) . . . . . 172
11.2 Coordinates of the top of the soil mass . . . . . . . . . . . . . . . . . . . . 173
13.1 Pipes properties (Tutorial 6) . . . . . . . . . . . . . . . . . . . . . . . . . . 186
14.1 Properties of the silty sand layer (Tutorial 7) . . . . . . . . . . . . . . . . . . 192
14.2 Properties of steel material (Tutorial 7) . . . . . . . . . . . . . . . . . . . . 192
15.1 Properties of the layers (Tutorial 8) . . . . . . . . . . . . . . . . . . . . . . 204
16.1 Settlement parameters (acc. Koppejan) of the soil layers (Tutorial 9) . . . . . 214
16.2 Coordinates of the top of the soil mass . . . . . . . . . . . . . . . . . . . . 215
18.1 Layer properties (Tutorial 11) . . . . . . . . . . . . . . . . . . . . . . . . . 232
19.1 Layer properties (Tutorial 12) . . . . . . . . . . . . . . . . . . . . . . . . . 244
20.2 Values of constant C (according to table E.1 of NEN 3650-1) . . . . . . . . . 256
20.3 Soil type as a function of the cohesion and the friction angle . . . . . . . . . 257
20.5 Bending factor (acc. to table 6 of NEN 3650-3) . . . . . . . . . . . . . . . . 257
21.7 Values of parameter µ according to NEN 3650-1 . . . . . . . . . . . . . . . 264
21.19 Friction displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
21.20 Classification of the soil type . . . . . . . . . . . . . . . . . . . . . . . . . 276
23.12 Moment and deflection coefficients for indirectly and directly transmitted stress
as a function of the bedding angle β , according to Table D.2 of NEN 3650-1 .
23.17 Set for calculation of the maximum stresses for load combination 1A . . . .
23.18 Set for calculation of the maximum stresses for load combination 1B . . . .
23.19 Set for calculation of the maximum stresses for load combination 3 . . . . .
23.20 Set for calculation of the maximum stresses for load combination 4 . . . . .

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1 General Information
D-G EO P IPELINE (formerly known as MDrill) has been developed especially for geotechnical
engineers and mechanical engineers. D-G EO P IPELINE’s graphical interactive interface requires just a short training period for novice users. This means that skills can focus directly on
the input of geotechnical and engineering data and on the drilling fluid pressure calculations
and strength pipeline calculations.
1.1

Preface
D-G EO P IPELINE is a graphical interactive Windows tool for designing pipelines installed by
using one of the three following techniques:

the horizontal directional drilling (HDD) technique
the micro-tunneling technique
the construction in trench technique
In case of HDD technique, D-G EO P IPELINE can be used to calculate the maximum allowable
pressure of the drilling fluid and to assess whether this maximum pressure remains higher
than the minimum required drilling pressure. The design is completed by means of a pipe
stress analysis.
In case of micro-tunneling, D-G EO P IPELINE can be used to calculate the minimal face support
pressure to prevent the possibility of collapse in of the soil in front of the micro tunneling shield
and also the maximum face support pressure which should not be exceeded to prevent uplift
of the soil above the micro tunneling machine or a blow out of drilling fluid towards the surface.
In case of installation in a trench, D-G EO P IPELINE can be used to check the uplift safety as the
soil cover above the pipeline may be insufficient to withstand the buoyant force of an empty
pipeline.
Easy and efficient
D-G EO P IPELINE has proved to be a powerful tool in the everyday engineering practice of
designing pipelines constructed by means of horizontal directional drilling, micro tunneling
or trenching. D-G EO P IPELINE’s graphical user interface allows both frequent and infrequent
D-G EO P IPELINE users to evaluate the feasibility of pipeline configurations.
Complete functionality
D-G EO P IPELINE provides the complete functionality for the design of pipelines installation.
Product integration
D-G EO P IPELINE is an integrated component of the Deltares Systems. This means that relevant data with MGeoBase (central project database), D-G EO S TABILITY formerly known as
MStab (stability analysis), MSeep (seepage) and D-S ETTLEMENT, formerly known as MSettle (settlements) can be exchanged. MGeobase is used to create and maintain a central
project database containing data on the measurements, geometry and soil properties of several cross-sections.
D-G EO P IPELINE also interacts with Scia Pipeline program for advanced structural analysis of
pipeline behavior by exporting the D-G EO P IPELINE results in a csv file.

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1.2

Installation of pipelines
Pipelines are an important part of the linear infrastructure. They are the lifelines of our modern
society. Successful operation of a pipeline system on long term is strongly related to the
quality of the engineering works carried out before the installation of the pipeline.
The installation of pipelines is carried out in trenches from times immemorial. After excavation
of the trench the pipeline is installed on the bottom of the trench and is subsequently covered
by the excavated soil. Since the seventies, last century, other techniques for pipeline installation are introduced. These so called trench less techniques such as horizontal directional
drilling and micro tunneling are applied on a large scale since the eighties. They provide a logical alternative when pipelines need to cross roads, railways, dikes, wetlands, rivers and other
structures that have to remain intact. These techniques minimize the impact of installation
activities in densely populated and economical sensitive areas.
The program D-G EO P IPELINE provides tools for the design of pipeline installation in a trench
and trench less, by using the micro tunneling technique or the horizontal directional drilling
technique. The tools allow the user to minimize the risks during and after installation.

1.2.1

Horizontal Directional Drilling technique
HDD techniqueD-G EO P IPELINE enables the fast design of a pipeline configuration, installed
using the horizontal directional drilling technique. With the horizontal directional drilling technique, three installation stages are considered:

Pilot drilling
Reaming the initial pilot borehole
Pulling back the pipeline

Figure 1.1: HDD / Pilot drilling (DCA-guidelines)

Figure 1.2: HDD / Pre-reaming (DCA-guidelines)

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Figure 1.3: HDD / Pull back operation (DCA-guidelines)

During the final stage, a drilling is carried out, using a relatively small drill bit, under the object
that has to be crossed – for example, a road, railway, waterway or a nature reserve. This initial
borehole is called a pilot hole. The diameter of the pilot hole is then enlarged using a reamer.
Depending on the required final borehole diameter, the borehole can be enlarged in several
stages using reamers of increasing diameters. After reaming, the diameter of the borehole
should be 1.3 to 1.5 times larger than the diameter of the pipeline. After preparing the pipeline
near the exit point of the borehole, the pipeline is finally pulled into the borehole.

Figure 1.4: Reamer and cutting wheel

During all drilling stages, drilling fluid is pumped under pressure into the borehole. The main
function of drilling fluid is to transport cuttings from the drilling head through the borehole
and to the ground surface. A specific minimum pressure is required for the transport function
of the drilling fluid. However, the fluid pressure in the borehole should not exceed a specific
maximum value. The maximum value is related to the strength of the soil around the borehole.
If the maximum fluid pressure is exceeded, a ‘blow-out’ may occur. Besides the pressure of
the drilling fluid, other factors play a role in the design process. Both the strength of the
pipeline during the pull back operation and the strength of the pipeline in operation need to be
sufficient to withstand the forces acting on the pipeline.
1.2.2

Micro Tunneling
Micro tunneling is the technique which uses a micro tunneling boring machine (MTBM) to
remove the soil. Micro tunneling usually starts horizontal at a certain level below the surface.
Start and reception shafts are created for the micro tunneling machine. In the start shaft a

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jacking frame and micro tunneling machine in front of pipe sections are installed. The jacks
push the pipe elements section by section ahead towards the reception shaft. As the length
of the advancing micro tunnel increases, the friction forces along the micro tunneling machine
and the pipe segments will increase. Lubrication fluid may be applied to reduce the friction.
Very often at the front of the Micro tunneling machine drilling fluid is used for soil removal and
front stabilization.

Figure 1.5: Jacking frame and micro tunneling machine in the start shaft

1.2.3

Installation in trench
The majority of the underground pipelines are installed in a trench. After excavation of the
trench the pipeline is installed on the bottom of the trench (Figure 1.6) and is subsequently
covered by the excavated soil. The interaction between the pipe and the condition of the soil
material, which is placed back in the trench plays an important role in the engineering of the
pipe.

Figure 1.6: Pipeline installation in a trench

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1.3

Features in standard module (HDD)
In the Netherlands, HDD technique has been used on a large scale since the 1980s. Since
the 1970s, Deltares (formerly known as GeoDelft) has been involved in the development and
execution of trench less technologies. Years of research have resulted in one of the first
design codes for HDD, as well as in a computer program. Since the release of the first version
in 1995, D-G EO P IPELINE provides users with the minimum and maximum drilling fluid pressure
during the different phases of construction. D-G EO P IPELINE can also analyze the stresses in
the pipeline during and after the installation for different pipeline materials.
This section contains an overview of D-G EO P IPELINE’s options available for Horizontal Directional Drilling (standard module).

1.3.1

Soil profile

Multiple layers. The two-dimensional soil structure can be composed of several soil
layers with an arbitrary shape and orientation. Each layer is connected to a particular
soil type.

Verticals. By placing verticals in the geometry, the coordinates for which output results
will be displayed can be defined.

Soil properties. The well-established constitutive models are based on common soil
parameters for strength and deformation of behavior of specific soil types.
1.3.2

Pipeline materials
D-G EO P IPELINE is capable of dealing with pipelines made of different materials: steel and
polyethylene. For both pipe materials, a database containing the material data is available.
The database enables a quick re-calculation for alternative material types and dimensions.

1.3.3

Factors
D-G EO P IPELINE applies partial safety factors to the soil parameters (weight, cohesion, friction
angle and Young’s modulus) and to the loads according either to the NEN series or to the
European Standard CEN.

1.3.4

Results
Following the analysis, D-G EO P IPELINE can display results in long table and graphical form.
The tabular report contains:

an echo of the input
soil mechanical calculation results per vertical
drilling fluid pressures calculation results per vertical
pulling force in the pipeline per characteristic point
strength pipeline calculation results
settlement results per vertical

A graphical output of the drilling fluid pressures for all drilling stages and vertical stresses per
vertical can also be viewed.

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1.4

Features in additional modules
D-G EO P IPELINE comes as a standard module (section 1.3), which can be extended further
with other modules to fit three other applications related to pipeline installation:

Micro Tunneling module (section 1.4.1)
Trenching module (section 1.4.2)
1.4.1

Micro Tunneling module
Face support pressures
The micro tunneling machine changes the stress conditions in the soil. The deviations from
the original stress conditions are largely determined by the size of the overcut and the applied
shield. Small deviations from the original conditions are acceptable as the stability of the soil
adjacent to the micro tunneling machine is maintained. A relative low face support pressure
may lead to collapse of the soil in front of the shield, which in turn may lead to subsidence
of the surface or to settlement of soil layers below a construction or pipeline. A relatively
high face support pressure can lead to a blow out of drilling fluid or may lead to heave of the
surface.

Figure 1.7: Face support pressures

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Thrust force
The micro tunneling machine is at the front of the advancing pipe sections. As the length of
the advancing micro tunnel increases, the friction forces along the micro tunneling machine
and the pipe segments increases. Lubrication fluid may be applied to reduce the friction.
D-G EO P IPELINE compares the predicted thrust force with the maximum allowable thrust force
of the pipeline.
Surface subsidence
During the micro tunneling drilling process the volume of removed soil is generally larger than
the volume of the tunnel (overcut). The volume difference will lead to soil movement towards
the borehole, which in turn will lead to surface subsidence. The magnitude of the subsidence
(trough) is also calculated.
Arching effect
D-G EO P IPELINE applies a reduced neutral soil load to incorporate the effect of arching. The
amount of reduction depends on the depth of the pipeline, diameter and the soil properties.
For micro tunneling the effect of arching on the soil load is calculated. Due to the relative
small overcut around the borehole arching is not completely developed.

Figure 1.8: Modelisation of the effect of arching

Pipeline stress analysis
For pipe stress analysis very often special programs need to be used. These programs need
an advanced set of soil mechanical parameters, provided by D-G EO P IPELINE. This will generate a complete spring model around the pipeline for further analysis.
1.4.2

Trenching module
Installation in a trench is the most common way of pipeline installation. In case of pipeline
installation in a trench the interaction between the pipe and the soil material, which is placed
back in the trench plays an important role in the development of the soil load. Besides the
condition of the soil material with which the trench is back-filled, the following parameters
determine the soil load for a pipeline in a trench:

Dimensions of the trench
Soil type in which the trench is excavated
Soil type with which the trench is back-filled

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Unit weight of the soil material with which the trench is back-filled
The stiffness of the pipeline

Figure 1.9: Pipeline installation in trench

Features

Graphical user interface for input of soil data.
Advanced input of the ground water pressure distribution.
Upheaval and Uplift check.
Graphical output of the calculated uplift safety factor.
Graphical output of the calculated upheaval safety.
3 dimensional pipeline configuration.
Calculation of settlement of the soil layers below the pipeline.
Output of soil mechanical parameters for an extensive pipeline stress analysis.

Initial soil load
For advanced pipe stress analyses very often special programs need to be used. These
programs need an advanced set of soil mechanical parameters, provided by D-G EO P IPELINE.
The programs will generate a complete spring model around the pipeline for further analyses.
The soil mechanical parameters include the initial soil load. In the period directly after the
installation of the pipeline in the trench, the compaction of the fill plays an important role in the
soil pipe interaction. The compaction of the fill leads to differential settlement of the fill above
the pipe and adjacent to the pipe.

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Figure 1.10: Compaction of the fill after pipeline installation

Uplift safety
Pipeline installation in wet soft soil environments may lead to buoyant behavior of the pipeline.
In case of superficial installation the soil cover above the pipeline may be insufficient to withstand the buoyant force of an empty pipeline.
1.5

History
D-G EO P IPELINE is formerly known as MDrill until version 5.1. This program is a dedicated tool
for designing pipelines constructed using the horizontal directional drilling technique (HDD),
the micro tunnelingor the construction in trench. Deltares has been developing D-G EO P IPELINE
since 1992.
The first successful pipeline installation using the HDD technique Horizontal Directional Drilling
was carried out under a river in the US. From 1979 onwards, the HDD technique gradually
broke through internationally. The first application in The Netherlands was in 1983/1984 for
the construction of a gas pipeline under the Buiten IJ in Amsterdam. Unlike conventional
construction methods, the HDD technique can be used to construct pipelines without digging
trenches and pits – for example, using sag pipes, pipe jacking or micro tunneling. And it also
significantly shortens the construction time.
After the first application of the HDD technique, the NV Nederlandse Gasunie (Dutch Gas
Corporation) took the initiative to form a research team to investigate the new construction
technique. GeoDelft was a member of that research team, which investigated the construction
of two pilot projects in the Netherlands.
The two pilot horizontal directional drillings were carried out in 1985. While the pipeline was
being installed, measurements were taken to gain a greater understanding of the behavior
of the soil around the borehole. The results of the research were used to define preliminary
guidelines that must be taken into account when designing and constructing pipelines using
the HDD method.
Since the first pilot projects, a large number of HDD’s have been carried out, and the HDD
technique has become a quick and reliable method for constructing cables and pipelines under

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waterways and other objects.
Continuation of the research has led to a greater store of knowledge about soil behavior, the
stresses in the pipes, and the fluid pressures in the borehole. The D-G EO P IPELINE computer
program was developed on the basis of this knowledge.
MDrill version 1.0 was first released in 1995. Some new features, such as the option for
performing a strength calculation, were added in 1998.
MDrill version 4.0 includes an adapted calculation of maximum allowable drilling fluid pressures and an adjusted strength calculation according to the NEN 3650 series.
MDrill version 5.1 includes an adapted calculation of maximum allowable drilling fluid pressures and an adjusted strength calculation according to the new NEN 3650 series. Horizontal
curves can be taken into account. The settlement calculation using the Koppejan or the Isotache models is also added. Bundled pipeline are now supported. A library with standard
pipes for steel and polyethylene is available. The mud pressure charts have been improved.
Exporting soil parameters in versatile format (*.csv) is possible.
D-G EO P IPELINE version 6.1 (2010) includes two new techniques for pipeline installation: the
Micro tunneling module (section 1.2.2) and the Construction in trench module (section 1.2.3).
New tutorials (7 to 12) have been added to explain the use of both techniques. Small bugs
have been solved: pulling forces for bundled pipes, (horizontal) projected length needed for
vertical testing and mud pressure plots, default values for maximum deflection of Steel and
PE have been exchanged, factor on modulus of subgrade reaction correctly used, in case of
bundles the load angle and bedding angle are given by user (not automatically set to 30 degrees any more), the maximum test pressure is increased. Moreover some minor changes in
the report have been made.
D-G EO P IPELINE version 6.2 (2012) includes an adaptation for dead end pipe ("Dead end"
pipe has no production phase). Moreover some minor issues have been solved.
D-G EO P IPELINE version 6.3 (2013) includes the following changes: the changes in the Dutch
norm NEN 3650:2012 series (NEN, 2012a,b,c) and NEN 3651:2012 (NEN, 2012d) are incorporated, it is possible to add traffic loads, safety factors from the European Standard CEN are
added, the report is available in French, the temperature stresses are calculated, the known
issue about thrusting forces is solved and the wrong usage of boundaries (for micro-tunneling)
is solved.
D-G EO P IPELINE version 14.1 (2014) For micro tunneling, the calculation of the minimum and
maximum face support pressures is updated so that the target value is between the minimum
and maximum values. The “Check on calculated stresses for load combination 1 (HDD)” is
now correctly performed. The linear settlement coefficient αg is now a user-defined value in
the Pipe Engineering window (section 4.6.3.1). For HDD - Strength calculation, the load factor
on installation finstall is used for the calculation of the axial bending stress σb (Equation 23.23).
D-G EO P IPELINE version 15.1 (2015) The default value of the allowable deflection of pipe for
steel is changed to 15% (instead of 5%), as prescribed by the NEN. For bundle, the piggability
is checked using the diameter of the considered pipe, not the equivalent diameter. A toggle
button Same scale X and Y axis
is implemented in the Input and Top View windows
(Figure 2.1), to switch between same scale for X and Y-axis and not same scale for X and
Y-axis. A Reset button in the Defaults window (Figure 4.43) is added to get the default factors
prescribed by the selected norm (NEN or CEN); when a factor differs from the norm, it is
displayed in red.

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D-G EO P IPELINE version 16.1 (2016) With this version, license(s) can be borrowed for a certain period allowing working without connection to the licence server (see section 3.2.5 for
more information).
1.6

Minimum System Requirements
The following minimum system requirements are needed in order to run and install the D-G EO P IPELINE
software, either from CD or by downloading from the Deltares website via MS Internet Explorer:

Operating systems:

Windows 2003,
Windows Vista,
Windows 7 – 32 bits
Windows 7 – 64 bits
Windows 8
Hardware specifications:
1 GHz Intel Pentium processor or equivalent
512 MB of RAM
400 MB free hard disk space
SVGA video card, 1024 × 768 pixels, High colors (16 bits)
CD-ROM drive
Microsoft Internet Explorer version 6.0 or newer (download from www.microsoft.com)
1.7

Definitions and Symbols
Co-ordinate system
The horizontal axis is defined as the X axis. The vertical axis is defined to be the Z -direction.
Upward is positive and downward negative. Perpendicular to the cross section is the Y direction. The L co-ordinate is the projection of the horizontal co-ordinate X along the pipeline
trajectory.

Figure 1.11: Co-ordinate system

Geometric data
A
Cross-section of the pipe: A = π (r02 − ri2 )
Do
Outer diameter of the pipe
Deq
Equivalent diameter of the bundled pipeline
Dg
Average diameter of the pipe: Dg = Do − dn
Di
Inner diameter of the pipe: Di = Do − 2 dn
d
Minimum wall thickness of the pipe: d = dn (1 − δt /100)
dn
Nominal wall thickness of the pipe
dn;eq
Equivalent nominal wall thickness of a bundled pipeline
Ib
Moment of inertia of the pipe: Ib = π (Do4 − Di4 ) /64

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Iw
lovercut
r0
rg
ri
Wb
Ww
δt

Moment of inertia of the wall: Iw = d3n /12
Difference between the hole radius and the outer radius of the product pipe (micro tunneling)
Outer radius of the pipe
Average radius of the pipe
Inner radius of the pipe
Resisting moment of the pipe: Wb = 2 Ib /Do
Resisting moment of the wall: Ww = d2n /6
Negative wall thickness tolerance

mm4 /mm
mm
mm
mm
mm
mm3
mm3 /mm
%

Pipe material data
Eb
Young’s modulus of the pipe
Reb
Yield strength of the steel pipe
Reb;short Yield strength of the polyethylene pipe at sort term
Reb;long Yield strength of the polyethylene pipe at long term
γb
Unit weight of the pipe material

N/mm2
N/mm2
N/mm2
N/mm2
kN/m3

Process data
pd
Design pressure
pt
Test pressure
∆t
Temperature variation

N/mm2
N/mm2
K

Pipeline configuration
Xleft
X-coordinate of the left point
Yleft
Y-coordinate of the left point
Zleft
(Vertical) Z-coordinate of the left point
Xright
X-coordinate of the right point
Yright
Y-coordinate of the right point
Zright
(Vertical) Z-coordinate of the right point
ϕleft
Left angle of the pipe
ϕright
Right angle of the pipe
Zlowest
Lowest level of the pipe
Rleft
Vertical bending radius of the pipe at the left side
Rright
Vertical bending radius of the pipe at the right side
Rrol
Bending radius of the rollers

m
m
m
m
m
m
radians
radians
m
m
m
m

Soil properties
a
Adhesion
a
Direct compression index acc. to Isotache model
b
Secular compression index acc. to Isotache model
c
Coefficient of secular compression rate acc. to Isotache model
c
Cohesion
cu
Undrained cohesion
Cp
Primary compression coefficient below Pc
Cp ’
Primary compression coefficient above Pc
Cs
Secondary compression coefficient below Pc
Cs ’
Secondary compression coefficient above Pc
E
Young’s modulus
G
Shear modulus: G = E/ (2 (1 + ν))
OCR
Over-consolidation ratio

kN/m2
–
–
–
kN/m2
kN/m2
–
–
–
–
kN/m2
kN/m2
–

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Pc
P OP
δ
ϕ
γunsat
γsat
γw
ν

Preconsolidation pressure
Pre-overburden pressure
Friction angle between the soil and the pipeline
Friction angle
Unsaturated (dry) unit weight
Saturated (wet) unit weight
Unit weight of water
Poisson’s ratio

Soil mechanical data
alub fluid Adhesion of the lubrification fluid
B
Width of the foundation element (= Do )
B1
Half width of the covered ground column
C
Compression index (soil dependent constant)
dc
Depth factor for the effect of the cohesion
dq
Depth factor for the effect of the soil cover
Fr
Permanent friction due to arching effect
Fmax
Maximal adhesion
h
Soil cover above the borehole
hp
Soil cover above the borehole in the incompressible layer
H
Soil cover above the top of the pipe if the pipe is situated in a compressible layer or thickness of the compressible layer if the pipe is
situated in an incompressible layer
kh
Horizontal modulus of subgrade reaction
kv;df
Modulus of subgrade reaction of the drilling fluid
kv;lub fluid Modulus of subgrade reaction of the lubrification fluid (micro tunneling)
kv,pipe
Vertical modulus of subgrade reaction of the pipe
kv,top
Vertical modulus of subgrade reaction of the soil upward
kv,bottom Vertical modulus of subgrade reaction of the soil downward
Ka
Active earth pressure ratio
K0
Neutral earth pressure ratio: K0 = 1 − sin ϕ
Kc
Load coefficient according to Brinch Hansen
Kq
Load coefficient according to Brinch Hansen
L
Length of foundation element
Nc
Bearing capacity factor for the effect of the cohesion
Nq
Bearing capacity factor for the effect of the soil cover
Nγ
Bearing capacity factor for the effect of the effective weight of the
soil under the foundation surface
pmax ’
Maximum passive vertical stress
Pwe
Ultimate vertical bearing capacity
qhe
Horizontal bearing capacity
qh,n
Neutral horizontal stress of the soil
qh,r
Neutral reduced horizontal stress of the soil
qk
Initial vertical stress of the soil
qn
Neutral vertical stress of the soil
qn,r
Reduced neutral vertical stress of the soil
qn,r,v
Reduced neutral vertical stress increased with a possible traffic load, including safety factors: qn,r,v = fQn1 × fQn2 ×

kN/m2
kN/m2
Radians
Radians
kN/m3
kN/m3
kN/m3
–

N/mm2
m
m
–
–
–
N/mm2
N/mm2
m
m
m

kN/m3
kN/m3
kN/m3
kN/m3
kN/m3
kN/m3
–
–
–
–
m
–
–
–
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2

(qn;r + fqv × qv )
qp
qp;max
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Passive vertical stress of the soil
Maximum passive vertical stress

N/mm2
N/mm2

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qv
sc
sq
sγ
W
zmax
δd
δlub fluid
ϕb
µ
σ0 ’
σc
σh ’
σv ’

Traffic load
Shape factor due to cohesion
Shape factor due to soil cover
Shape factor due to effective weight of the soil under the foundation
element
Maximal axial friction along the pipeline
Maximal displacement
Relative displacement of the soil column
Delta lubrification fluid
Average friction angle over the height of the borehole
Percentage of compaction depending on the type of fill and type of
compaction
Effective isotrope stress: σ00 = (σv0 + σh0 ) /2
Vertical effective stress at the compressibility border
Effective horizontal stress at the pipe center:σh0 = K × sigma0v
Effective vertical stress at the pipe center

Stress analysis data
f1
Factor of friction between pipe and pipe-rollers
f2
Friction between pipe and drilling fluid
f3
Factor of friction between pipe and soil
Frr
Direct re-rounding factor
Frr ’
Indirect re-rounding factor
gt
Curved force
Kb
Moment coefficient for directly transmitted stress at the bottom of
the pipeline, depending on the bedding angle β
Kb ’
Moment coefficient for indirectly transmitted stress at the bottom of
the pipeline, depending on the bedding angle β
Kt
Moment coefficient for directly transmitted stress at the top of the
pipeline, depending on the bedding angle β
Kt ’
Moment coefficient for indirectly transmitted stress at the top of the
pipeline, depending on the bedding angle β
ky
Direct deflection factor depending on the bedding angle β
ky ’
Indirect deflection factor depending on the bedding angle β
Lb
Length of the curved part of the pipeline
Lrol
Length of the pipeline on the roller-lane
Ltotal
Length of the pipeline from the entry to the exit point
L2
Length of the pipeline in the straight part of the borehole
T
Total pulling force in the pipeline
T1
Pulling force due to friction of the pipeline on the roller-lane
T2
Pulling force due to friction between pipe and drilling fluid
T3a
Pulling force in the curved part of the borehole due to soil reaction
T3b
Pulling force in the curved part of the borehole due to curved forces
Pw
Part of pipe filled with fluid during the pull-back operation
qr
Soil reaction
Q
Weight of the pipeline filled with water
Qeff
Effective weight of the pipeline
Qfilling
Weight of the filling (water)
Quplift
Uplift force
Qpipe
Weight of the pipeline
R
Bending radius
y
Maximum displacement
α
Load angle

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N/mm2
–
–
–
kN/m
m
m
Radians
Radians
–
N/mm2
N/mm2
N/mm2
N/mm2

–
N/mm2
–
–
–
N/mm
–
–
–
–
–
–
mm
mm
mm
mm
N
N
N
N
N
%
N/mm2
N/mm
N/mm
N/mm
N/mm
N/mm
mm
mm
Radians

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General Information

α
β
δy
δ0
δ1
γfill
λ
σb
σpt
σpx
σpy
σqn
σqr
σt

Alpha pipe material (for polyethylene)
Bedding angle
Calculated deflection of the pipe
Allowable deflection of the pipe
Allowable deflection of the pipe (piggability)
Unit weight of the filling fluid
Characteristic stiffness pipeline-soil
Axial bending stress
Internal stress around the pipeline caused by test pressure pt
Axial internal stress
Internal stress around the pipeline caused by design pressure pd
Tangential stress (directly transmitted) as a result of the bending
Tangential stress (indirectly transmitted) as a result of the bending
Axial stress due to pull-back

–
Radians
%
%
%
N/mm3
mm−1
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2
N/mm2

Drilling fluid data
dp/dz Flow resistance per unit length of borehole
floss
Circulation loss factor
h
Height between drilling head and exit point of the drilling fluid
L
Distance in the borehole between the drilling head and the exit point
of the drilling fluid
pmax;d
Maximum drilling fluid pressure for drained conditions
pmax;und Maximum drilling fluid pressure for undrained conditions
p1
Static pressure of the drilling fluid column
p2
Excess pressure necessary to maintain the annular flow of drilling
fluid with cuttings in the borehole
Q
Calculated flow rate
Qann
Annular back-flow rate
Qreq
Requested flow rate necessary to initiate flow of drilling fluid
Rb
Radius of the borehole
Rp;max
Maximum allowable radius of the plastic zone
u
Pore pressure
εg;max
Maximum deformation of the borehole
γdf
Unit weight of the drilling fluid
µdf
Plastic viscosity of the drilling fluid
τdf
Yield point of the drilling fluid

m3 /s
m3 /s
m3 /s
m
m
kN/m2
–
kN/m3
kN.s/m2
kN/m2

Partial safety factors
fburst
Safety factor on hydraulic heave
fsilo
Overburden factor on silo effect
fu
Safety factor on water pressure u
fuplift
Safety factor on uplift
fσ h
Safety factor on the horizontal effective stress
N
Stability ratio for the calculation of the minimal support pressure
S
Factor of importance
δ0
Maximum allowable deflection of the pipe
δ1
Maximum allowable deflection of the pipe for piggability
γimp;long Safety factor on implosion at long term
γimp;short Safety factor on implosion at short term
γm
Partial material factor (only for steel).
γm;test
Partial material factor test pressure (only for steel)

–
–
–
–
–
–
–
%
%
–
–
–
–

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kN/m3
–
m
m
kN/m2
kN/m2
kN/m2
kN/m2

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Contingency factors
fc
Contingency factor on the cohesion (c or cu )
fcover
Contingency factor on soil cover
fE
Contingency factor on the Young’s modulus E
fk
Overall factor on bending moment: fk = fM × finstall × fR
fkv
Contingency factor on the bedding constant kv
fM
Contingency factor on the bending moment M
fpress;bore Contingency factor on the pressure borehole
fpull
Contingency factor on the pulling force T
fQn2
Contingency factor on the soil load qn
fR
Contingency factor on bending radius R
fthrust
Contingency factor on thrsut force
fϕ
Contingency factor on the tangent of the friction angle ϕ
fγ
Contingency factor on the total unit weight γ

–
–
–
–
–
–
–
–
–
–
–
–
–

Load factors
finstall
Load factor on installation
fpd
Load factor on design pressure pd
fpd;comb Load factor on design pressure pd in combination
fpt
Load factor on test pressure pt
fQn1
Load factor on soil load qn
ftemp
Load factor on stress due to the temperature variation ∆t
fqv
Load factor on traffic load qv

–
–
–
–
–
–
–

Abbreviations
HDD
Horizontal Directional Drilling
MTBM
Micro Tunneling Boring Machine
PE
Polyethylene
LC
Load Combination

1.8

Getting Help
From the Help menu, choose the Manual option to open the User Manual of D-G EO P IPELINE
in PDF format. Here help on a specific topic can be found by entering a specific word in the
Find field of the PDF reader.

1.9

Getting Support
Deltares Systems tools are supported by Deltares. A group of 70 people in software development ensures continuous research and development. Support is provided by the developers
and if necessary by the appropriate Deltares experts. These experts can provide consultancy
backup as well.
If problems are encountered, the first step should be to consult the online Support at:
www.deltares.com in menu ‘Software’. Different information about the program can be found
on the left-hand side of the window (Figure 1.12):

In ‘Support - Frequentely asked questions’ are listed the most frequently asked technical
questions and their answers.

In ‘Support - Known issues’ are listed the issues of the program.
In ‘Release notes D-Geo Pipeline’ are listed the differences between an old and a new
version.

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General Information

Figure 1.12: ‘Products’ menu of Deltares Systems website (www.deltaressystems.com)

If the solution cannot be found there, then the problem description can be e-mailed (preferred)
or faxed to the Deltares Systems support team. When sending a problem description, please
add a full description of the working environment. To do this conveniently:

Open the program.
If possible, open a project that can illustrate the question.
Choose the Support option in the Help menu. The System Info tab contains all relevant
information about the system and the DSeries software. The Problem Description tab
enables a description of the problem encountered to be added.

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Figure 1.13: Support window, Problem Description tab

After clicking on the Send button, the Send Support E-Mail window opens, allowing
sending current file as an attachment. Marked or not the Attach current file to mail
check-box and click OK to send it.

Figure 1.14: Send Support E-Mail window

The problem report can either be saved to a file or sent to a printer or PC fax. The document
can be emailed to geo.support@deltaressystems.nl or alternatively faxed to +31(0)88 335
8111.
1.10

Deltares
Since January 1st 2008, GeoDelft together with parts of Rijkswaterstaat /DWW, RIKZ and
RIZA, WL |Delft Hydraulics and a part of TNO Built Environment and Geosciences are forming the Deltares Institute, a new and independent institute for applied research and specialist advice. Founded in 1934, GeoDelft was one of the world’s most renowned institutes for
geotechnical and environmental research. As a Dutch national Grand Technological Institute
(GTI), Deltares role is to obtain, generate and disseminate geotechnical know-how. The institute is an international leader in research and consultancy into the behavior of soft soils (sand
clay and peat) and management of the geo-ecological consequences which arise from these
activities. Again and again subsoil related uncertainties and risks appear to be the key factors

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General Information

in civil engineering risk management. Having the processes to manage these uncertainties
makes Deltares the obvious partner in risk management for all parties involved in the civil and
environmental construction sector. Deltares teams are continually working on new mechanisms, applications and concepts to facilitate the risk management process, the most recent
of which is the launch of the concept "GeoQ" into the geotechnical sector.
For more information on Deltares, visit the Deltares website: www.deltares.com.
1.11

Deltares Systems
Deltares Systems (formerly known as Delft GeoSystems) converts Deltares’s knowledge into
practical geo-engineering services and software. Deltares Systems has developed a suite
of software for geotechnical engineering. Besides software, Deltares Systems is involved in
providing services such as hosting on-line monitoring platforms, hosting on-line delivery of
site investigation, laboratory test results, etc. As part of this process Deltares Systems is
progressively connecting these services to their software. This allows for more standardized
use of information, and the interpretation and comparison of results. Most software is used
as design software, following design standards. This however, does not guarantee a design
that can be executed successfully in practice, so automated back-analyses using monitoring
information are an important aspect in improving geotechnical engineering results. For more
information about Deltares Systems’ geotechnical software, including download options, visit
www.deltaressystems.com.

1.12

On-line software (Citrix)
Besides purchased software, Deltares Systems tools are available as an on-line service. The
input can be created over the internet. Heavy duty calculation servers at Deltares guarantee
quick analysis, while results are presented on-line. Users can view and print results as well
as locally store project files. Once connected, clients are charged by the hour.
For more information, please contact the Deltares Sales team:
sales@deltaressystems.com.

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2 Getting Started
This Getting Started chapter aims to familiarize the user with the structure and user interface
of D-G EO P IPELINE. The Tutorial section which follows uses a selection of case studies to
introduce the program’s functions.
2.1

Starting D-G EO P IPELINE
To start D-G EO P IPELINE, click Start on the Windows menu bar and then find it under Programs,
or double-click a D-G EO P IPELINE input file that was generated during a previous session.
For an D-G EO P IPELINE installation based on floating licenses, the Modules window may appear at start-up (section 3.2.5). Check that the correct modules are selected and click OK.
When D-G EO P IPELINE is started from the Windows menu bar, the last project that was worked
on will open automatically, unless the program has been configured otherwise under Tools:
Program Options (section 3.2).

2.2

Main window
When D-G EO P IPELINE is started, the main window is displayed (Figure 2.1). This window
contains a menu bar (section 2.2.1), an icon bar (section 2.2.2), a View Input window (section 2.2.3) displaying the pre-selected or most recently accessed project, an info bar (section 2.2.4), a title panel (section 2.2.5) and a status bar (section 2.2.6).

Figure 2.1: Main Window

The first time D-G EO P IPELINE is started after installation, the View Input window will be closed.
When a new file is created, the default model is Horizontal directional drilling and the project
name is Project1.

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2.2.1

The menu bar
To access the D-G EO P IPELINE menus, click one of the items on the menu bar.

Figure 2.2: D-G EO P IPELINE menu bar

The menus contain the following functions:
File

Project
Soil
Geometry
GeoObjects

Loads
Pipe
Defaults
Calculation
Results
Tools
Window
Help
2.2.2

Standard Windows options for opening, saving and sending files as well
as several D-G EO P IPELINE options for exporting and printing the active
window and reports (section 3.1).
Definition of the model types, options for Project Properties and View
Input File (section 4.1).
Definition of soil type properties (section 4.2).
Definition of layers, soil types and piezometric lines (section 4.3).
Definition of the border between compressible top layers and underlying non-compressible soil layers, the border between impermeable and
permeable soil layers and definition of the verticals (X-coordinates) for
which results will be shown (section 4.4).
Definition of the traffic loads if present (section 4.5).
Definition of the pipeline configuration and input of pipeline parameters
(section 4.6).
Input of factors (section 4.7).
A wide range of calculation options. Determine the settlements and
stresses along the verticals (chapter 5).
Graphical or tabular output of the results (chapter 6).
Options for editing D-G EO P IPELINE program default settings (section 3.2).
Default Windows options for arranging the D-G EO P IPELINE windows
and choosing the active window.
Online Help (section 1.8).

The icon bar
The buttons on the icon bar can be used to quickly access frequently used functions (see
below).

Figure 2.3: D-G EO P IPELINE icon bar

Click on the following buttons to activate the corresponding functions:
Start a new D-G EO P IPELINE project.
Open the input file of an existing project.
Save the input file of the current project.
Print the contents of the active window.

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Display a print preview of the current contents of the View Input window.
Open the Project Properties window. Here the project title and other identification
data can be entered, and the View Layout and Graph Settings for the project can be
determined.
Start the calculation.
Display the contents of online Help.
Display the first page of the Deltares Systems website: www.deltaressystems.com
2.2.3

View Input
The View Input window displays the geometry and additional D-G EO P IPELINE input for the
current project. The window has three tabs:

Geometry
In this view (Figure 2.4), the positions and soil types of different layers can be defined, inspected and modified. For more information about these general options for
geometrical modeling, see chapter 7. See also the description of the Geometry menu
(section 4.3).

Figure 2.4: View Input window, Geometry tab

Input
In this view (Figure 2.5), the additional D-G EO P IPELINE-specific input can be defined,
inspected and modified. See below in this section for more information about the various
options.

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Figure 2.5: View Input window, Input tab

Top View
In this view (Figure 2.6), the top view of the pipeline longitudinal cross section is shown.

Figure 2.6: View Input window, Top View tab

The panel on the left of the view includes buttons for entering data and manipulating the
graphical view. Click the following buttons to activate the corresponding functions:

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Select and Edit mode
In this mode, the left-hand mouse button can be used to select a previously-defined
verticals or loads in the View Input mode. Item can then be deleted or modified
by dragging or resizing, or by clicking the right-hand mouse button and choosing
options from the menu displayed. Pressing the Escape key return the user to this
Select and Edit mode.
Pan button
Click this button to change the visible part of the drawing by clicking and dragging
the mouse.
Add point(s) to boundary / PL-line
Click this button to add points to all types of lines (lines, polylines, boundary lines,
PL-lines). By adding a point to a line, the existing line is split into two new lines. This
provides more freedom when modifying the geometry.
Add single lines(s)
Click this button to add single lines. When this button is selected, the first left-hand
mouse click will add the info bar of the new line and a “rubber band” is displayed
when the mouse is moved. The second left-hand mouse click defines the end point
(and thus the final position) of the line. It is now possible to either go on clicking start
and end points to define lines, or stop adding lines by selecting one of the other tool
buttons, or by clicking the right-hand mouse button, or by pressing the Escape key.
Add polyline(s)
Click this button to add poly-lines. When this button is selected, the first left-hand
mouse click adds the starting point of the new line and a “rubber band” is displayed
when the mouse is moved. A second left-hand mouse click defines the end point
(and thus the final position) of the first line in the poly-line and activates the “rubber
band” for the second line in the poly-line. Every subsequent left-hand mouse click
again defines a new end point of the next line in the poly-line. It is possible to end
a poly-line by selecting one of the other tool buttons, or by clicking the right-hand
mouse button, or by pressing the Escape key.
Add PL-line(s)
Click this button to add a piezometric level line (PL-line). Each PL-line must start
at the left limit and end at the right limit. Furthermore, each consecutive point must
have a strictly increasing X co-ordinate. Therefore, a PL-line must be defined from
left to right, starting at the left limit and ending at the right limit. To enforce this, the
program will always relocate the first point clicked (left-hand mouse button) to the left
limit by moving it horizontally to this limit. If trying to define a point to the left of the
previous point, the rubber band icon indicates that this is not possible. Subsequently
clicking on the left side of the previous point, the new point will be added at the end
of the rubber band icon instead of the position clicked.
Zoom in
Click this button to enlarge the drawing, then click the part of the drawing which is to
be at the center of the new image. Repeat if necessary.
Zoom out
Click this button, then click on the drawing to reduce the drawing size. Repeat if
necessary.
Zoom rectangle
Click this button then click and drag a rectangle over the area to be enlarged. The
selected area will be enlarged to fit the window. Repeat if necessary.
Measure the distance between two points
Click this button, then click the first point on the View Input window and place the
cross on the second point. The distance between the two points can be read at the
bottom of the View Input window. To turn this option off, click the escape key.

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Add calculation vertical
Click this button to graphically define the position of a vertical.
Undo zoom
Click this button to undo the zoom. If necessary, click several times to retrace each
consecutive zoom-in step that was made.
Zoom limits
Click this button to display the complete drawing.
Same scale for X and Y axis
Click this button to use the same scale for the horizontal and vertical directions.
Automatic regeneration of geometry on/off
When selected, the program will automatically try to generate a new valid geometry
whenever geometry modifications require this. During generation, (poly)lines (solid
blue) are converted to boundaries (solid black), with interjacent layers. New layers
receive a default material type. Existing layers keep the materials that were assigned
to them. Invalid geometry parts are converted to construction elements.
Automatic regeneration may slow down progress during input of complex geometry,
because validity will be checked continuously.
Undo
Click this button to undo the last change(s) made to the geometry.
Redo
Click this button to redo the previous Undo action.
Delete
Click this button to delete a selected element. Note that this button is only available
when an element is selected.
2.2.4

Info bar
This bar situated at the bottom of the View Input window displays the co-ordinates of the
current position of the cursor and the distance between two points when the icon Measure the
distance between two points
is selected from the Edit panel.

2.2.5

Title panel
This panel situated at the bottom of the main window displays the project titles, as entered on
the Identification tab in the Project Properties window (section 4.1.2).

2.2.6

Status bar
This bar situated at the bottom of the main window displays a description of the selected icon
of the icon bar (section 2.2.2) or of the View Input window (section 2.2.3).

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2.3

Files
*.dri

*.drd
*.drs

*.drd
*.geo
*.set
*.err
*.gef

2.4
2.4.1

Input file (ASCII):
Contains the D-G EO P IPELINE specific input. After interactive generation, this file
can be used in subsequent D-G EO P IPELINE analyses.
Dump file (ASCII):
Contains calculation results used for graphical output.
Setting file (ASCII):
Working file with settings data. This file does not contain any information that is
relevant for the calculation, but only settings that apply to the representation of
the data, such as the grid size.
Dump file (ASCII):
Contains calculation results used for graphical and report output.
Input file (ASCII):
Contains the geometry data that can be shared with other D-Series programs.
Working file (ASCII):
Contains program settings data.
If there are any errors in the input, they are described in this file.
Measurements data in self describing Geotechnical Exchange Format.

Tips and Tricks
Keyboard shortcuts
Keyboard shortcuts given in Table 2.5 are another way to reach the features of D-G EO P IPELINE
directly without selecting it from the bar menu. These shortcuts are also indicated in the
corresponding sub-menus.
Table 2.5: Keyboard shortcuts for D-G EO P IPELINE

Keyboard shortcut
Ctrl + N
Ctrl + O
Ctrl + S
F12
Shift + Ctrl + C
Ctrl + P
Ctrl + M
Ctrl + T
F9
Ctrl + R
Ctrl + U

Deltares

Opened window
New
Open
Save
Save As
Copy Active Window to Clipboard
Print Report
Model
Materials
Start Calculation
Report
Drilling Fluid Pressures Plots

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2.4.2

Exporting figures and reports
All figures in D-G EO P IPELINE such as top view and graphical output can be exported in WMF
(Windows Meta Files) format. In the File menu, select the option Export Active Window to
save the figures in a file. This file can be later imported in a Word document for example or
added as annex in a report. The option Copy Active Window to Clipboard from the File menu
can also be used to copy directly the figure in a Word document.
The report can be entirely exported as PDF (Portable Document Format) or RTF (Rich Text
Format) file. To look at a PDF file Adobe Reader can be used. A RTF file can be opened
and edited with word processors like MS Word. Before exporting the report, a selection of the
relevant parts can be done with the option Report Selection (section 6.1).

2.4.3

Copying part of a table
It is possible to select and then copy part of a table in another document (an Excel sheet for
example). If the cursor
is placed on the left-hand side of a cell of the table, the cursor
changes in an arrow which points from bottom left to top right. Select a specific area by using
the mouse (see a in Figure 2.7). Then, using the copy button (or ctrl+C) this area can be
copied.

Figure 2.7: Selection of different parts of a table using the arrow cursor

To select a row, click on the cell before the row number (see b) in Figure 2.7). To select a
column, click on the top cell of the column (see c) in Figure 2.7). To select the complete table,
click on the top left cell (see d) in Figure 2.7).
In some tables the buttons Cut, Copy, and Paste

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are also present at the left hand.

Deltares

3 General
This chapter contains a detailed description of the available menu options for inputting data
for a project, and for calculating and viewing the results. The examples in the Tutorial section
provide a convenient starting point for familiarization with the program.

General options
Besides the familiar Windows options for opening and saving files, the File menu contains a
number of options specific to D-G EO P IPELINE:

New

Select this option to display the New File window (Figure 3.1). Three choices are available to create a new geometry:
Select New geometry to display the View Input window, showing only the geometry limits (with their defaults values) of the geometry;

3.1.1

File menu

Select New geometry wizard to create a new geometry faster and easier using
the wizard option (involving a step-by-step process for creating a geometry, see
section 4.3.2);

3.1

Select Import geometry to use an existing geometry.

Figure 3.1: New File window

Copy Active Window to Clipboard
Use this option to copy the contents of the active window to the Windows clipboard so
that they can be pasted into another application. The contents will be pasted in either
text format or Windows Meta File format.

Export Active Window
Use this option to export the contents of the active window as a Windows Meta File
(*.wmf), a Drawing Exchange File (*.dxf) or a text file (*.txt).

Export Report
This option allows the report to be exported in a different format, such as PDF or RTF.

Export Results as xml
This option allows the inputs and results to be exported in an XML format.

Export Results as csv
This option allows the inputs and results to be exported with the SCIA pipeline wizard
in a csv format (Excel). For detailed information, refer to section 3.1.2.

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Page Setup
This option allows definition of the way D-G EO P IPELINE plots and reports are to be
printed. The printer, paper size, orientation and margins can be defined as well as
whether and where axes are required for plots. Click Autofit to get D-G EO P IPELINE to
choose the best fit for the page.

Print Preview Active Window
This option will display a print preview of the current contents of the View Input or
Results windows.

Print Active Window
This option prints the current contents of the View Input or Results windows.

Print Preview Report
This option will display a print preview of the calculation report.

Print Report
This option prints the calculation report.
3.1.2

Option ”Export Results as csv”
For advanced structural analyses, for example the SCIA Pipeline program (Sci) can be used or
an other program. Such a program has advanced options for structural modeling and allows
for accurate analyses of stress distribution (Figure 3.2). In order to do so, such a program
for an advanced pipe stress analysis needs accurate soil mechanical parameters, which are
supplied by D-G EO P IPELINE in a CSV (comma-separated values) format file by means of the
option Export Results as csv from the File menu bar of D-G EO P IPELINE.

Figure 3.2: 3D configuration in SCIA Pipeline

The CSV file contains the following data’s (calculated without safety factors).
General
Company

[-]

Software

[-]

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Name of the company who performed the calculation
with D-G EO P IPELINE.
Version number of D-G EO P IPELINE used.

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General

Date
Time

[yyyy/mm/dd]
[hh:mm:ss]

Date of the calculation with D-G EO P IPELINE.
Time of the calculation with D-G EO P IPELINE.

P1(x)
P1(y)
P1(z)
P2(x)
P2(y)
P2(z)
Length Pipe

[m]
[m]
[m]
[m]
[m]
[m]
[m]

X co-ordinate of the begin point of the pipeline.
Y co-ordinate of the begin point of the pipeline.
Z co-ordinate of the begin point of the pipeline.
X co-ordinate of the end point of the pipeline.
Y co-ordinate of the end point of the pipeline.
Z co-ordinate of the end point of the pipeline.
Length along the pipeline between the begin point P1
and the end point P2.

Pipe nr
Diameter Tube
Thickness Tube
Material Tube

[-]
[mm]
[mm]
[-]

Pipeline data’s

Diameter of the pipe.
Wall thickness of the pipe.

Note: Pipeline data’s are not calculated (only user inputted), but are needed in order to
prepare the SCIA Pipeline file.
Calculation verticals
Section nr
[-]
x
[m]
y
[m]
z
[m]

Horizontal soil mechanical data
From
[m]
Curved
[boolean]
Delta
[m]
f
Qa
Qn
Qc
Qp
C1
C2
Gap
UCF(XX)

[m]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m3 ]
[kN/m3 ]
[mm]
[-]

Number of the calculation vertical.
X co-ordinate of the calculation vertical.
Y co-ordinate of the calculation vertical.
Z co-ordinate of the calculation vertical.

Position along the pipeline.
Presence or not of curved part along the pipeline.
Horizontal position of the pipeline measured perpendicular from line P1-P2.
Horizontal settlement of the soil.
Horizontal active soil pressure.
Horizontal neutral soil pressure.
Horizontal consolidation pressure.
Horizontal passive soil pressure.
Horizontal modulus of subgrade reaction of the soil.
Horizontal modulus of subgrade reaction of the soil.
Gap
Uncertainty on parameter XX.

Note: Horizontal soil mechanical data are given at both left and right sides of the pipe section.
Vertical soil mechanical data
From
[m]
Curved
[boolean]

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Position along the pipeline.
Presence or not of curved part along the pipeline.

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Delta

[m]

f
Qa
Qn
Qc
Qp
C1
C2
Gap
UCF(XX)

[m]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m3 ]
[kN/m3 ]
[mm]
[-]

Vertical position of the pipeline measured perpendicular from line P1-P2.
Vertical settlement of the soil.
Vertical active soil pressure.
Vertical neutral soil pressure.
Vertical consolidation pressure.
Vertical passive soil pressure.
Vertical modulus of subgrade reaction of the soil.
Vertical modulus of subgrade reaction of the soil.
Gap
Uncertainty on parameter XX.

Note: Vertical soil mechanical data are given at both top and bottom sides of the pipe section.
Water
Water height
C1
QP
UCF(XX)

[mm]
[kN/m3 ]
[kN/m2 ]
[-]

Axial soil data for friction
From
[m]
Coef_Mu_x
[-]
Cx
[kN/m3 ]
Coef_Mu_rx
[-]
Crx
[kN/m3 ]
Factor
[-]
UCF(XX)
[-]

3.2

Unit weight of water.
Water pressure.
Uncertainty on parameter XX.

Position along the pipeline.
Friction coefficient in axial direction.
Stiffness of the friction spring.
Friction coefficient in axial direction.
Stiffness of the friction spring.
Factor on friction.
Uncertainty on parameter XX.

Tools menu
On the menu bar, click Tools and then choose Options to open the Program Options window.
In this window, the user can optionally define their own preferences for some of the program’s
default values through the following tabs:

(section 3.2.1) View tab
(section 3.2.2) General tab
(section 3.2.3) Locations tab
(section 3.2.4) Language tab
(section 3.2.5) Modules tab

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General

3.2.1

Program Options - View

Figure 3.3: Program Options window, View tab

Toolbar
Status bar
Title panel

3.2.2

Mark the relevant check-box to display the tool bar and/or status bar
(section 2.2.6) each time D-G EO P IPELINE is started.
Mark this check-box to display the project titles, as entered on the Identification tab of the Project Properties window (section 4.1.2), in the title
panel (section 2.2.5) at the bottom of the View Input window.

Program Options - General

Figure 3.4: Program Options window, General tab

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Startup with

Save on
Calculation
Use Enter key to

3.2.3

Click one of these toggle buttons to determine how a project should be
initiated each time D-G EO P IPELINE is started.
No project: Use the buttons in the toolbar or the options in the File
menu to open an existing project or to start a new one.
Last used project: The last project to be worked on is opened automatically.
New project: A new project is created comprising a sheet pile wall with
a "dummy" soil layer on both sides.
Note that the Startup with option is ignored when D-G EO P IPELINE is
started by double-clicking on an input file.
The toggle buttons determine how input data is saved prior to calculation. It can either be saved automatically, using the same file name
each time, or a file name can be specified every time the data is saved.
Use the toggle buttons to determine the way the Enter key is used in
D-G EO P IPELINE: either as an equivalent of pressing the default button
(Windows style) or to shift the focus to the next item in a window (for
users accustomed to the DOS version(s) of the program).

Program Options - Locations

Figure 3.5: Program Options window, Locations tab

Working
directory
Use MGeobase
database

Settlement
program

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D-G EO P IPELINE will start up with a working directory for selection and
saving of files. Either choose to use the last used directory, or specify
a fixed path.
Enable this check-box to specify the location of the MGeoBase
database with material data, geometric data etc. Use of this option also
requires once-off local installation of Interbase client software, assuming that the database is residing on a server on which server software
has already been installed.
The calculation of the settlement of the soil layers below the pipeline
is performed externally by D-S ETTLEMENT (formerly known as MSettle), the settlement calculation program of the Deltares Systems tools.
Therefore, the directory where the program is installed must be specified by clicking the Browse button.

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General

3.2.4

Program Options - Language

Figure 3.6: Program Options window, Language tab

Interface language
Output language

3.2.5

Currently, the only available interface language is English.
The output languages English, German, Dutch and French are supported. The selected output language will be used in all exported
reports and output plots.

Program Options - Modules
For a D-G EO P IPELINE installation based on floating licenses, the Modules tab can be used to
claim a license for the particular modules that are to be used. If the Show at start of program
check-box is marked then this window will always be shown at start-up.
For a D-G EO P IPELINE installation based on a license dongle, the Modules tab will just show
the modules that may be used.

Figure 3.7: Program Options window, Modules tab

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Click this button to see which modules are (at this moment) in used and
who (within the company) is using them.
Click this button to borrow the selected modules for a certain period. The
modules will be taken from the server pool and will be available on this
computer even if no connection to the license server is available. Set the
date and time for the expiration of the borrowing and press OK.
Click this button to end the borrow immediately.

3.3

Help menu
The Help menu allows access to different options.

3.3.1

Error Messages
If errors are found in the input, no calculation can be performed and D-G EO P IPELINE opens
the Error Messages window displaying more details about the error(s). Those errors must
be corrected before performing a new calculation. To view those error messages, select the
Error Messages option from the Help menu. They are also written in the *.err file. They will
be overwritten the next time a calculation is started.

Figure 3.8: Error Messages window

3.3.2

Manual
Select the Manual option from the Help menu to open the User Manual of D-G EO P IPELINE in
PDF format. Here help on a specific topic can be found by entering a specific word in the Find
field of the PDF reader.

3.3.3

Deltares Systems Website
Select Deltares Systems Website option from the Help menu to visit the Deltares Systems
website (www.deltaressystems.com) for the latest news.

3.3.4

Support
Use the Support option from the Help menu to open the Support window in which program
errors can be registered. Refer to section 1.9 for a detailed description of this window.

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3.3.5

About D-G EO P IPELINE
Use the About option from the Help menu to display the About D-G EO P IPELINE window which
provides software information (for example the version of the software).

Figure 3.9: About D-G EO P IPELINE window

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4 Input
Before the design calculations can be started, data for the project needs to be input. The
examples presented in the Tutorial section (chapter 8) can be a convenient starting point.
4.1

Project menu
On the menu bar (section 2.2.1), click Project to display the following menu options:

(section 4.1.1) Model to select the required analysis model.
(section 4.1.2) Properties to enter a project identification and change the default settings
for viewing data.
(section 4.1.3) View Input File to inspect the D-G EO P IPELINE ASCII input file.
4.1.1

Model
On the menu bar, click Project and then choose Model to open the Model window.

Figure 4.1: Model window

Model

Ends at surface

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Select the technique for pipeline installation:
Horizontal directional drilling, see section 1.3;
Micro tunneling, see section 1.4.1;
Construction in trench, see section 1.4.2;
If Horizontal directional drilling is selected, the safety factors according
to either the Dutch Standard NEN or to the European Standard CEN
can be applied. For more information, refer to section 4.7.1.1.
Enable this check-box if the pipeline ends at surface. In this case,
D-G EO P IPELINE will automatically calculate the vertical co-ordinate Z
of the exit point of the pipeline (see section 4.6.1).

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Settlement

4.1.2

Enable the check-box Use settlement to calculate the vertical displacement of the soil below the pipeline due to installation. D-G EO P IPELINE
will use the D-S ETTLEMENT computer program. The required settlement
model (Koppejan or Isotache) must be selected. For background information, see section 21.10.2 and section 21.10.1 respectively for Koppejan and Isotache models.
Note: The check-box Use settlement is available only when the program D-S ETTLEMENT (formerly known as MSettle) is installed, and when
the location of the executable (DSettlement.exe) is specified in the Locations tab of the Program Options window (section 3.2.3).
Note: The pipeline settlement can also be entered manually (if available) in the Calculation Verticals window (refer to section 4.4.2).

Project Properties
On the menu bar, click Project and then choose Properties to open the input window. The
Project Properties window has two tabs, which allow the settings for the current project to be
changed:

Identification, to specify project identification data.
View Input, to define the appearance of items in the View Input window.
Project Properties - Identification
Use the Identification tab to specify the project identification data:

Figure 4.2: Project Properties window, Identification tab

Titles

Date

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Use Title 1 to give the project a unique, easily recognizable name. Title
2 and Title 3 can be added to indicate specific characteristics of the
calculation. The three titles will be included on printed output.
The date entered here will be used on printouts and graphic plots for
this project. Either mark the Use current date check-box to automatically use the current date on each printout, or enter a specific date.

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Input

Drawn by
Project ID
Annex ID

Enter the name of the user performing the calculation or generating the
printout.
Enter a project identification number.
Specify the annex number of the printout.

Enable the check-box Save as default to use these settings every time D-G EO P IPELINE is
started or a new project is created.
Project Properties – View Input
Use the View Input tab to define the appearance of the View Input window (section 2.2.3).

Figure 4.3: Project Properties window, View Input tab

Display
Info Bar

Calculation Verticals
Points

Enable this check-box to display the information bar at the bottom of the Outline View window.
Enable this check-box to display the legend.
Enable this check-box to display the x and y axis with the same
scale.
Enable this check-box to display the layers in different colors.
Enable this check-box to display the rulers.
Enable this check-box to draw a circle at the origin.
Enable this check-box to use the large cursor instead of the small
one.
Enable this check-box to display the verticals.
Enable this check-box to display the points.

Labels
Points
Calculation Verticals
Layers

Enable this check-box to display the point labels.
Enable this check-box to display the vertical labels.
Enable this check-box to display the layer labels.

Legend
Same scale for x and y
axis
Layer colors
Rulers
Origin
Large Cursor

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Layers labels as
This choice is available only if the Layers check-box of the Labels sub-window is marked.
There are three ways to display the legend of the layers:
Layer Numbers
The legend displays one box for each layer. Each layer (and
therefore each box) is displayed in a different standard color.
Next to each box, the layer number and the material name are
displayed, corresponding to the color and number of the layer in
the adjacent Geometry window.
Material Numbers
The legend displays one box for each material. Each material
(and therefore each box) is displayed in a different color which
can be changed by the user (see section 7.3.3). Next to each
box, the material number and name are displayed, corresponding to the color and number of the material in the adjacent Geometry window.
Material Names
The legend displays one box for each material. Each material
(and therefore each box) is displayed in a different color which
can be changed by the user (see section 7.3.3). Next to each
box, only the material name is displayed, corresponding to the
color and name of the material in the adjacent Geometry window.

Grid
Show grid
Snap to Grid
Grid distance

Enable this check-box to display the grid points.
Enable this check-box to ensure that objects align to the grid
automatically when they are moved or positioned in a graph.
Enter the distance between two grid points.

Enable the Save as default check-box to use the current settings every time D-G EO P IPELINE
is started.
4.1.3

View Input File
On the menu bar, click Project and then choose View Input File to display an overview of the
input data.
The data will be displayed in the D-G EO P IPELINE main window. Click on the Print Active
icon to print the file.
Window

4.2

Soil menu
The Soil menu is used to enter the soil properties for the analysis. In the Soil menu, choose
Materials to open the Materials input window in which the soil type properties can be defined.
The Properties can either be imported directly from an MGeoBase database (Database tab),
or be inputted manually (Parameters tab):

Manual input of standard parameters (section 4.2.1);
Manual input of settlement parameters acc. to Koppejan (section 4.2.2);
Manual input of settlement parameters acc. to Isotache (section 4.2.3);
Import from database (section 4.2.4).

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4.2.1

Materials – Standard
If the Use settlement check-box in the Model window (section 4.1.1) is unmarked, the following
window is displayed.

Figure 4.4: Materials window, Parameters tab

Total Unit Weight
Above phreatic level
Total Unit Weight Below
phreatic level
Cohesion
Phi
Cu top
Cu bottom
Emod top
Emod bottom
Adhesion

Friction angle (Delta)

Poisson ratio (Nu)

The unit weight of the unsaturated soil above the user-defined
phreatic line.
The unit weight of the saturated soil below the user-defined
phreatic line.
Cohesion of the soil.
Angle of internal friction of the soil.
The apparent undrained cohesion cu at the top of the layer.
The apparent undrained cohesion cu at the bottom of the layer.
Young’s modulus of the soil at the top of the layer.
Young’s modulus of the soil at the bottom of the layer.
Adhesion of the soil. The adhesion is only available if the Construction in trench or Micro Tunneling model have been selected
in the Model window (section 4.1.1).
Friction angle between soil and pipeline. The delta friction angle
is only available if the Construction in trench or Micro Tunneling
model have been selected in the Model window (section 4.1.1).
Poisson ratio of the soil.

The Young’s modulus E and the Poisson ratio ν are used to calculate G, the shear modulus:

G=
4.2.2

E
2(1 + ν)

(4.1)

Materials – Settlement Koppejan
If the Use settlement check-box in the Model window (section 4.1.1) is marked and the Koppejan model is selected, D-G EO P IPELINE will calculate the settlements according to the Koppejan
model. Therefore, the Koppejan parameters need to be put in as shown in Figure 4.5. For
background information, refer to section 21.10.2.

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Figure 4.5: Materials window, Parameters tab (Settlement acc. to Koppejan)

Over-consolidation Ratio (OCR)

Primary compression coefficient below
preconsolidation pressure (Cp)
Primary compression coefficient above
preconsolidation pressure (Cp’)
Secondary compression coefficient
below preconsolidation pressure (Cs)
Secondary compression coefficient
above preconsolidation pressure (Cs’)

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The Over-Consolidation Ratio (OCR) is defined
as the ratio of pre-consolidation pressure and
initial in situ vertical effective stress.
The primary compression coefficient Cp is used
to calculate the primary settlement.
The primary compression coefficient Cp ’ is used
to calculate the primary settlement.
The secondary compression coefficient Cs is
used to calculate the secondary (time dependent) settlement.
The secondary compression coefficient Cs ’ is
used to calculate the secondary (time dependent) settlement.

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4.2.3

Materials – Settlement Isotache
If the Use settlement check-box in the Model window [section 4.1.1] is unmarked and the
Isotache model is selected, D-G EO P IPELINE will calculate the settlements according to the
Isotache model. Therefore, the Isotache parameters need to be put in as shown in Figure 4.6.
For background information, see section 21.10.1.

Figure 4.6: Materials window, Parameters tab (Settlement acc. to Isotache)

Direct compression
index (a)
Secular compression
index (b)
Coefficient of secular
compression rate (c)
Pre-overburden
pressure (POP)
Overconsolidation
ratio (OCR)

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The direct compression index a relates natural strain during recompression or swell to the change of vertical effective stress.
The secular compression index b relates natural strain during
virgin loading to the change of vertical effective stress.
The coefficient of secular compression rate c relates natural
strain to the change of time. A zero value indicates non-creeping
soil.
The Pre-Overburden Pressure (P OP ) is defined as the preconsolidation pressure minus the initial in situ vertical effective
stress.
The Over-Consolidation Ratio (OCR) is defined as the ratio
of pre-consolidation pressure and initial in situ vertical effective
stress.

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4.2.4

Materials – Database
The Database tab in the Materials window is only available if a location of an MGeobase
database was specified in the Locations tab of the Program Options window (section 3.2.3).
Select the Database tab in the Materials window to see the available soil types. Select a soil
to import the soil type with associated properties.
type, and use the Import button

Figure 4.7: Materials window, Database tab

4.3

Geometry menu
On the menu bar, click Geometry to display the menu options. These options are explained
in the following sections.

New (section 4.3.1). Start creating a new geometry manually.
New Wizard (section 4.3.2). Create a new geometry using a wizard.
Import (section 4.3.3). Import a geometry file in the D-series exchange format.
Import geometry from database (section 4.3.4). Import geometry from a database.
Export (section 4.3.5). Save a geometry file for exchange with other Deltares Systems
programs.
Export as Plaxis/Dos (section 4.3.6). Save a geometry file in a different format.
Limits (section 4.3.7). Set the range of the horizontal coordinates.
Points (section 4.3.8). Add or manipulate points.
Import PL-line (section 4.3.9). Import a PL-line file in the D-Series exchange format.
PL-lines (section 4.3.10). Add or manipulate piezometric level lines.
Phreatic line (section 4.3.11). Define phreatic level lines.
Layer s (section 4.3.12). Define or modify layer boundaries and corresponding soil
types.
PL-lines per layer (section 4.3.13). Select the piezometric level line at the bottom and
top of each layer.
Check geometry (section 4.3.14). Check the validity of the geometry.

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Input

4.3.1

New
Select this option to display the View Input (Geometry) window, showing only the geometry
limits (with their default values) of the geometry. It is possible to now start modeling the
geometry (for more information on this subject, see chapter 7). However, it is possible to
create a new geometry faster and easier using the Geometry Wizard (section 4.3.2). This
wizard involves a step-by-step process for creating geometry.

4.3.2

New Wizard
The New Wizard is usually the fastest and easiest way to start creating new geometry. The
wizard uses predefined shapes and soil types.
To use the geometry wizard, click the Geometry menu and choose New Wizard. This wizard
provides the following step-by-step guidance:

Basic layout
Shape selection
Shape definition
Material types
Summary

New Wizard – Basic Layout

Figure 4.8: New Wizard window (Basic Layout)

In the Basic Layout window (Figure 4.8), the basic framework within which the project is
defined can be entered. The graphic at the top of the window explains the required input.
When satisfied with the input, just click the Next button to display the next input screen.

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New Wizard – Shape Selection

Figure 4.9: New Wizard window (Top Layer Shape)

In the Top Layer Shape window (Figure 4.9), one of nine default top-layer shapes can be
selected. A red frame indicates the selected shape. Click the Previous button to return to the
Basic Layout screen, or the Next button to display the next input screen with shape-specific
input data.
New Wizard – Shape definition

Figure 4.10: New Wizard window (Top Layer Specification)

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The Top Layer Specification window (Figure 4.10) enables to specify the sizes of the selected
top layer shape.
New Wizard – Material Types

Figure 4.11: New Wizard window (Material Types)

In the Material Types window (Figure 4.11), the materials used for the layers in the project
can be specified. The number of layers was defined in the first screen (Basic Layout). The
materials that can be chosen from are predefined (see Table 4.10).
Table 4.10: Unsaturated and saturated weight of the predefined materials

Material type
Soft Clay
Medium Clay
Stiff Clay
Loose Sand
Dense Sand
Loose Aggregate
Dense Aggregate
Peat

Unsaturated weight
[kN/m3 ]
14
17
19
17
19
17
19
12

Saturated weight
[kN/m3 ]
14
17
19
19
21
19
21
12

The materials for each layer can be selected individually (using the selection boxes at the
left-hand side of the screen) or one material for each layer at once can be selected (using the
selection box at the top right of the screen). The parameters of each material can also be
reviewed.

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New Wizard – Summary

Figure 4.12: New Wizard window (Summary)

The Summary window (Figure 4.12) displays an overview of the data entered in the previous
wizard screens. If necessary, click Previous to go back to any screen and change the data
as required. Clicking Finish will confirm the input and display the geometry in the View Input
Geometry window. In this window, the geometry can be edited or completed graphically as
described in chapter 7. Of course, the Geometry menu options can also be used for this
purpose (section 4.3).
4.3.3

Import
This option displays a standard file dialog in which an existing geometry can be selected
stored in a geometry file, or in an existing input file for D-G EO S TABILITY (formerly known as
MStab), D-S ETTLEMENT (formerly known as MSettle), MSeep and D-S HEET P ILING (formerly
known as MSheet). For a full description of these programs and how to obtain them, visit
www.deltaressystems.com.
When selecting the geometry, it is imported into the current project, replacing the current
geometry. The imported geometry is displayed in the View Input (Geometry) window. It is
also possible to use this option to analyze the settled geometry at different stages, as all other
input is retained.

4.3.4

Import geometry from database
To be able to import a geometry from a database, this option has to be provided with the
purchased version of D-G EO P IPELINE.
To import a geometry from a database do the following:

Click Import from Database in the Geometry menu.
The Select Geometry dialog will appear.

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Again, the imported geometry will replace the current one and will be displayed in the View
Input (Geometry) window.
Note: This option is only available when the correct database directory has been specified
using the Locations tab in the Program Options menu (see section 3.2.3). For more information on MGeoBase, visit www.deltaressystems.com.
4.3.5

Export
This option displays a standard Save As dialog that enables the user to choose a directory, a
file name and a format in which to save the current geometry to a file. The file will be saved in
the standard geometry format for the Deltares Systems programs (*.geo). Files in this format
can be used in a multitude of Deltares Systems programs, such as D-G EO S TABILITY (formerly
known as MStab), D-S ETTLEMENT (formerly known as MSettle), MSeep and D-S HEET P ILING
(formerly known as MSheet). For a full description of these programs and how to obtain them,
visit www.deltaressystems.com.

4.3.6

Export as Plaxis/DOS
This option displays the Save As Plaxis/DOS dialog that enables the user to choose a directory and a file name in which to save the current geometry. The file will be saved using
the old DOS-style geometry format for the Deltares Systems programs. Files in this format
can be used by the finite element program Plaxis and in old DOS-based versions of Deltares
Systems programs such as D-G EO S TABILITY (DOS) and MZet (DOS).
Saving files of this type will only succeed, however, if the stringent demands imposed by the
old DOS style are satisfied:

number of layers ≤ 20
number of PL-lines ≤ 20
number of lines per boundary < 50
total number of points ≤ 500

To be able to differentiate between an old DOS-style file and a normal geometry file, the file
dialog that prompts for a new file name for the old DOS-style geometry file suggests a default
file name, prefixing the current name with a ‘D’.
4.3.7

Limits
Use this option to edit the geometry limits.

Figure 4.13: Geometry Limits window

A limit is a vertical boundary defining the ‘end’ at either the left or right side of the geometry.
It is defined by an X-coordinate only.

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Note: This is the only type of element that cannot be deleted. Moreover, the values entered
here are ignored if they resulted in an invalid geometry.
4.3.8

Points
Use this option to add or edit points that can be used as part of layer boundaries or PL-lines. A
point is a basic geometry element defined by its coordinates. Since the geometry is restricted
to two dimensions, it is allowed to define an L and Z co-ordinates only.

Figure 4.14: Points window

L Co-ordinate
Z Co-ordinate

Projection of the horizontal co-ordinate along the pipeline trajectory.
Vertical co-ordinate.

Note: When a point is to be deleted, the system will check whether the point is used as part
of a PL-line or layer boundary. If so, a message will be displayed.

Figure 4.15: Confirm window for deleting used points

When Yes is clicked, all layer boundaries and/or PL-lines using the point will also be deleted.
Every change made using this window (Figure 4.14) will only be displayed in the underlying
View Input (Geometry) window after closing this window using the OK button. When this
button is clicked, a validity check is performed on the geometry. Any errors encountered
during this check are displayed in a separate window. These errors must be corrected before

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closing this window by clicking the OK button. Of course, it is always possible to close the
window using the Cancel button, but this will discard all changes.
4.3.9

Import PL-line
This option displays a standard file dialog in which an existing PL-line, created with the program WATEX and stored in a PL-line file (*.mpl), can be selected.
WATEX (Deltares, 2004) is a reliable prediction tool to assess the pore pressure behavior. It
consists of transient analytical solutions, put together by the conditions of continuity of head
and discharge. The user specifies a number of locations, where the pore pressure response
is required.
When a PL-line file is selected, the Options for Import of Pl-line window (Figure 4.16) is
displayed. When clicking the OK button, then the PL-line is added to the current PL-lines
in the project.

Figure 4.16: Options for Import of PL-line window

4.3.10

PL-Lines
Use this option to add or edit Piezometric Level lines (PL-lines) to be used in the geometry. A
PL-line represents the hydraulic head Hydraulic head of the water in the pores of the soil. A
PL-line can be defined for the top and bottom of each soil layer (see section 4.3.13). The bottom soil layer is assumed to be infinitely thick. Here, therefore, only one PL-line is necessary
for the top of that layer. Pore pressures in this layer are hydrostatic with increasing depth.

Figure 4.17: PL-Lines window

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In the lower part of the window, the buttons Add, Insert and Delete PL-lines can be used. The
selection box on the left can be used to navigate between PL-lines that have already been
defined. Use the table to add/edit the points identifying the PL-lines. It is only possible to
select points that are not attached to layer boundaries (section 4.3.12).
Note: It is only possible to manipulate the Point number column – that is, the coordinate
columns are purely for informative purposes. To edit the coordinates of the points, choose the
Points option from the Geometry menu (see section 4.3.8).
Every change made using this window will only be displayed in the underlying View Input
(Geometry) window after closing this window using the OK button. When clicking this button,
a validity check is performed on the geometry. Any errors encountered during this check are
displayed in a separate window. These errors must be corrected before closing this window
using the OK button. Of course, it is always possible to close the window using the Cancel
button, but this will discard all your changes.
4.3.11

Phreatic Line
Use this option to select the PL-line that acts as a phreatic line. The phreatic line (or groundwater level) is used to mark the border between dry and wet soil.

Figure 4.18: Phreatic Line window

Select the appropriate line number from the drop-down list and click the OK button.
Note: At least one PL-line has to be defined to be able to pick a phreatic line from the
drop-down list.
4.3.12

Layers
This option enables to add or edit layers to be used in the geometry. A layer is defined by its
boundaries and its material. Use the Boundaries tab to define the boundaries for all layers by
choosing the points that identify each boundary.

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Figure 4.19: Layers window, Boundaries tab

On the left-hand side of the window, it is possible to add, insert, delete or select a boundary.
In the table on the right, it is possible to modify or add the points that identify the selected
boundary.
Note: It is only possible to select points that are not attached to PL-lines (section 4.3.10).
Note: It is only possible to manipulate the Point number column, because the coordinate
columns are purely for informative purposes. To manipulate the coordinates of the points,
choose the Points option in the Geometry menu (see section 4.3.8).
Note: When inserting or adding a boundary, all points of the previous boundary (if this exists)
are automatically copied. By default, the material of a new layer is set equal to the material of
the existing layer just beneath it.
The Materials tab enables to assign materials to the layers.

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Figure 4.20: Layers window, Materials tab

On the left of the screen, a list containing all defined materials (see the Materials option in the
Soil menu in section 4.2.1) is displayed. On the right, a list of all defined layers together with
their assigned materials (if available) is displayed.
To assign a material to a layer, first select that layer on the right of the window. Then select
the required material on the left of the window. Finally, click the Assign button .
In case of settlement calculation using the Koppejan or the Isotache model (section 4.1.1), the
loading is defined by marking the Load check-box of one or several layers. D-G EO P IPELINE
assumes that those layers are non-uniform loads.
Every change made using this window will only be displayed in the underlying View Input
(Geometry) window after closing this window by clicking the OK button. When clicking this
button, a validity check is performed on the geometry. If errors are encountered, a dialog
window asks if auto-correction should be tried. Remaining errors are reported and can be
corrected manually. The error correction is confirmed by clicking the OK button and discarded
by clicking the Cancel button.
4.3.13

PL-lines per Layer
Use this option to define the top and bottom PL-lines for the defined layers. The PL-lines
represent the pore pressure in a soil layer. For each soil layer (except the deepest layer), two
PL-line numbers can be entered – one that corresponds to the top of the soil layer, and one
that corresponds to the bottom. Therefore, different PL-lines can be defined for the top and
bottom of each soil layer. To do this, select the appropriate PL-line at top / PL-line at bottom
field and enter the appropriate number.

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Figure 4.21: PL-line per Layer window

Note: For the deepest soil layer, no second PL-line number is required. For this layer a
hydrostatic increase of the pore pressure is automatically assumed from the pore pressure at
the top of the layer downwards.
The following values can be used as PL-line numbers (N):
0 < N < 99 The number corresponds to one of the PL-lines defined during the geometry
input. Capillary water pressures are not used – that is, if a negative water
pressure is calculated for a point above the phreatic line, the water pressure
in that point is defined as 0.
N=0
Each point within the layer has a water pressure equal to 0 (define 0 for PLline at top of layer).
N = 99
It is possible to have a number of overlying soil layers with a non-hydrostatic
pore pressure (for example, a number of layers consisting of cohesive soil). In
this case, a large number of PL-lines would have to be calculated, one or two
for each layer. To avoid this, D-series software is able to interpolate across
layer boundaries. For layers with a non-hydrostatic pore pressure, 99 can be
entered as the PL-line number. For this layer, the interpolation will take place
between the PL-line belonging to the first soil layer above with a real PL-line
number, and the PL-line belonging to the first soil layer below with a real PLline number. The first and the last soil layer must therefore always have a real
PL-line number.
Note: A real PL-line number is not equal to 99.

Water pressures above the phreatic line are set to zero. An example using two different PLlines is given in Figure 4.22 showing how the pore pressure varies in the vertical.

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PL-line 2
PL-line 1

SAND
CLAY

1
2

99
99

SAND
CLAY2

2
2
1
1

99
99
99
2

SAND

Figure 4.22: PL-lines and vertical pressure distribution

When clicking the OK button, the program performs a validity check on the geometry. Any
errors encountered during this check are reported. A dialog window enables to disregard or
correct the errors. The error correction is confirmed by clicking the OK button and discarded
by clicking the Cancel button.
4.3.14

Check Geometry
When this option is selected, the program checks the validity of the geometry (section 7.2) with
respect to the requirements. If the geometry complies with all the requirements, a message
will confirm this.

Figure 4.23: Information window to confirm a valid geometry

If any errors are encountered during this check, they are displayed in a separate window.
4.4

GeoObjects menu

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4.4.1

Boundaries Selection
Click GeoObjects on the menu bar and select Boundaries Selection to define the boundaries
between compressible top layers and under laying non-compressible layers and the boundary
between drained (i.e. cohesive) top layers and under laying non-cohesive (i.e. undrained)
layers (Figure 4.24). This is done by choosing the layer number of the underlying layer.

b)
Figure 4.24: Boundaries Selection window for (a) HDD/Micro-tunneling and (b) for
Trenching

The boundary between compressible and non-compressible layers is drawn as a blue bold
line and the boundary between drained and undrained layers (i.e. impermeable and permeable layers) is drawn as a black bold line in the Input tab of the View Input window (see
section 2.2.3).
4.4.2

Calculation Verticals
Click GeoObjects on the menu bar and select Calculation Verticals to define the L-coordinate
for each vertical. D-G EO P IPELINE will perform calculations along each of these verticals. At
least one vertical is necessary to perform any calculation.
The verticals must be placed within the left and right project limits.For an accurate impression
of the change in drilling fluid pressure along the pipeline, it is advised to use at least 10-15
verticals.
It is possible to generate a number of verticals using the Auto generation of L co-ordinates option and clicking the Generate button
. D-G EO P IPELINE will generate verticals between
the First and Last co-ordinates with a fixed width, entered in the Interval field.

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Figure 4.25: Calculation Verticals window

L-coordinate

Additional
Settlement

First L
Last L
Interval
Generate

4.5
4.5.1

Defines the locations in geometry in the L direction where the calculations are performed. L represents distance along the pipe line projection in the horizontal plane incremented with the entry coordinate. The
L-coordinate value must increase with each vertical.
Enter an additional settlement for the selected vertical. This settlement
will be added to the calculated settlement (according to Koppejan or
Isotache) in the table of the Deformation section of the Report window
(section 6.2.2).
L co-ordinate of the starting point of generated verticals.
L co-ordinate of the ending point of generated verticals.
Interval between generated verticals.
Click this button to generate automatically verticals from First to Last L
with the mentioned Interval.

Loads menu
Traffic Loads
On the menu bar, click Loads and then choose Traffic Loads to open the corresponding input window in which the positions of traffic loads can be defined. Traffic loads will have an
influence on the calculated soil load stress, only for the calculation verticals situated

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Figure 4.26: Traffic Loads window

X co-ordinate at
start
X co-ordinate at
end
Load type

4.6
4.6.1

Enter the X co-ordinate of the starting point of the selected traffic load.
Enter the X co-ordinate of the ending point of the selected traffic load.
According to article C.5.1 of NEN 3650-1 (NEN, 2012a), two load models are considered, depending on the type of road:
For dual carriageways and regional roads, Graph I (i.e. ’Load
Model 3’ of European standard EN NEN-1991-2) is assumed;
For other roads, Graph II (i.e. ’Fatigue Load Model 2, Lorry 4’
of European standard EN NEN-1991-2) is assumed. This load
model covers the ’set of frequent lorries’ which can occur on European roads, such as described in EN NEN-1991-2, with exception of the special transports).
For more information, refer to section 21.14.

Pipe menu
Pipeline Configuration
On the menu bar, click Pipe and then choose Pipeline Configuration to open the corresponding input window in which the geometric characteristics of the pipeline can be defined. The
Pipeline Configuration window displayed depends on the selected model.

4.6.1.1

Pipeline Configuration for HDD
If the Horizontal directional drilling option in the Model window (section 4.1.1) is selected, the
Pipeline Configuration window shown in Figure 4.27 is displayed.

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Figure 4.27: Pipeline Configuration window (for HDD)

Left point
X-coordinate
Left point
Y-coordinate
Left point
Z-coordinate

Right point
X-coordinate
Right point
Y-coordinate
Right point
Z-coordinate

Angle left
Angle right
Bending radius
left
Bending radius
right
Bending radius
pipe on rollers
Lowest level of
pipe
Angle of pipe
Pulling direction
product pipe
X1

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X-coordinate of the left point which corresponds whether the entry or
the exit point of the pipeline (called Xleft in Figure 4.28).
Y-coordinate of the left point which corresponds whether the entry or
the exit point of the pipeline (called Yleft in Figure 4.28).
Z-coordinate (i.e. vertical level) of the left point which corresponds
whether the entry or the exit point of the pipeline (called Zleft in Figure 4.28). This coordinate corresponds with the surface level for
X = Xleft and is automatically calculated by the program.
X-coordinate of the right point which corresponds whether the entry or
the exit point of the pipeline (called Xright in Figure 4.28).
Y-coordinate of the right point which corresponds whether the entry or
the exit point of the pipeline (called Yright in Figure 4.28).
Z-coordinate of the right point which corresponds whether the entry or
the exit point of the pipeline (called Zright in Figure 4.28). This coordinate corresponds with the surface level for X = Xright and is automatically calculated by the program.
Left angle of the pipe (called ϕleft in Figure 4.28).
Right angle of the pipe (called ϕright in Figure 4.28).
Bending radius of the pipe at the left side (called Rleft in Figure 4.28).
Bending radius of the pipe at the right side (called Rright in Figure 4.28).
Only available for HDD model. Bending radius on the pipe roller, depending on the diameter of the product pipe (called Rrollers in Figure 4.28).
Lowest level of the pipe (called Zlowest in Figure 4.28).
Horizontal angle of the lowest straight part of the configuration.
The pulling force at characteristics points can be calculated for a pulling
direction From left to right (i.e. the left point is the entry point) and From
right to left (i.e. the right point is the entry point).
X co-ordinate of the beginning point of the horizontal bending (see Figure 4.28).

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Y co-ordinate of the beginning point of the horizontal bending (see Figure 4.28).
X co-ordinate of the ending point of the horizontal bending (see Figure 4.28).
Y co-ordinate of the ending point of the horizontal bending (see Figure 4.28).
Radius of the horizontal bending (called Rbending in Figure 4.28).
From the drop-down menu, select the direction of the horizontal bending (Left or Right). For example, the horizontal bending of Figure 4.28
has a left direction.

X2
Y2
Radius
Direction

Top view

(X2 ; Y2)

b en
din

(X1 ; Y1)

(Xright ; Yright)

entry

exit

(Xleft ; Yleft)

(Xright ; Zright)
(Xleft ; Zleft)

roll
ers

ϕright

ϕleft
R

R left

rig
ht

Zlowest

Figure 4.28: Schematization of the pipeline (HDD)

Needless to say, the coordinates must be defined properly. For example, the X-coordinate of
the right point must have a higher value than the coordinate of the left point.
The pipeline configuration is given at the center of the pipe. It is assumed that during all
drilling stages (pilot, drill and pullback) the defined center of the pipeline is the same. From
each pipe, the diameter of the pipe as well as the diameter of the hole must be known.
4.6.1.2

Pipeline Configuration for Micro tunneling
If the Micro tunneling option in the Model window (section 4.1.1) is selected, the Pipeline
Configuration window shown in Figure 4.29 is displayed.

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Figure 4.29: Pipeline Configuration window (for Micro tunneling)

Thrusting direction
product pipe

The thrusting force can be calculated for a pulling direction From left
to right (i.e. the left point is the entry point) and From right to left
(i.e. the right point is the entry point).
Refer to the table above for the definition of the other parameters

Note: To model a horizontal micro-tunneling, enter an Angle left and an Angle right of 0.
4.6.1.3

Pipeline Configuration for Construction in trench
If the Construction in trench option in the Model window (section 4.1.1) is selected, the
Pipeline Configuration window shown in Figure 4.30 is displayed. Different pipe materials
can be defined along the pipeline.

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Figure 4.30: Pipeline Configuration window (Construction in trench)

Begin X
Begin Y
Begin Z
Material quality
Outer diameter
Wall thickness
Unit weight pipe material
Width trench bottom
Slope 1:x
Offset

End trench X
End trench Y
End trench Z

4.6.2

X co-ordinate of the begin point of the trench section.
Y co-ordinate of the begin point of the trench section.
Z co-ordinate of the begin point of the trench section.
Description of the material quality. The data in this field is
used in the report.
Outer diameter of the pipe in mm.
Wall thickness of the pipe in mm.
Unit weight of the pipe material.
Width of the trench bottom.
Slope of the trench.
Distance between the bottom of the trench and the bottom of
the pipeline.

X co-ordinate of the end point of the last trench section.
Y co-ordinate of the end point of the last trench section.
Z co-ordinate of the end point of the last trench section.

Product Pipe Material Data

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4.6.2.1

Product Pipe Material Data for HDD
If the Horizontal directional drilling option in the Model window (section 4.1.1) is selected, click
Pipe on the menu bar and then choose Product Pipe Material Data to open the Product Pipe
Material Data window in which the characteristics of the pipe material can be entered. This
data will be used for the strength calculation. Depending on the choice between steel and
polyethylene, different values for the parameters need to be specified.
Steel pipe
Different types of steel pipes can be selected from the database (see Figure 4.31). Userdefined values can also be defined for a steel pipeline.

Figure 4.31: Product Pipe Material Data window (Steel)

Pipe material

Material quality
Negative wall thickness
tolerance
Yield strength
Partial material factor
Partial material factor test
pressure

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Young’s modulus

Outer diameter product
pipe (Do)
Wall thickness
Unit weight pipe material

Design pressure

Test pressure

Temperature variation

Modulus of elasticity of the pipe (Eb ) in N/mm2 . For steel, the
default value is 205800 N/mm2 . It is used to determine the
stresses in the pipeline in a strength calculation.
Outer diameter of the product pipe (Do ) in mm.
Wall thickness of the pipe (dn ) in mm.
Unit weight of the pipe material (γb ), used to determine the
pulling force in the pipeline. For steel, the default value is
78.5 kN/m3 .
Design pressure (pd ) in Bar, used to determine the stresses
caused by internal pressure in LC 2 (section 23.5.3) and in
LC 4 (section 23.5.5).
Test pressure (pt ) in Bar, used to determine the stresses
caused by test pressure in LC 2 (section 23.5.3) and in LC 4
(section 23.5.5).
Temperature variation (∆t) in ◦ C, used to determine the
stresses caused by temperature variation in LC 4 (section 23.5.5).

When clicking the Database button
, the Steel pipes library window appears (Figure 4.32) in which the material quality (i.e. nominal pipe size), the outer diameter, the wall
thickness and the yield strength of different steel pipes can be imported.

Figure 4.32: Steel pipes library window

Polyethylene pipe
Different types of polyethylene pipes can be selected from the database (see Figure 4.34).
User-defined values can also be defined for a PE pipeline.

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Figure 4.33: Product Pipe Material Data window (Polyethylene)

Pipe material

Material quality
Young’s modulus (short)
Young’s modulus (long)
Allowable strength (short)
Allowable strength (long)
Tensile factor

Outer diameter product
pipe (Do)
Wall thickness
Unit weight pipe material

Design pressure

Test pressure

Temperature variation

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Choice between steel or polyethylene.
Click this button to import the name, the outer diameter, the
wall thickness and the yield strength of a pipe material from
the D-G EO P IPELINE library (see Figure 4.34).
Description of the polyethylene quality. The data in this field
is used in the report.
Modulus of elasticity of the pipe (Eb ) at short term in N/mm2 .
Modulus of elasticity of the pipe (Eb ) at long term in N/mm2 .
Yield strength of the pipe at sort term (Reb;short ) in N/mm2 .
Yield strength of the pipe at long term (Reb;long ) N/mm2 .
The tensile factor a (also called alpha pipe material) is the
relation between the allowable tensile strength and the allowable bending strength. The default value is 0.65.
Outer diameter of the product pipe (Do ) in mm.
Wall thickness of the pipe (dn ) in mm, used to determine the
stresses in a strength calculation.
Unit weight of the pipe material (γb ), used to determine the
pulling force in the pipeline. For PE, the default value is
9.54 kN/m3 .
Design pressure (pd ) in Bar, used to determine the stresses
caused by internal pressure in LC 2 (section 23.5.3) and in
LC 4 (section 23.5.5).
Test pressure (pt ) in Bar, used to determine the stresses
caused by test pressure in LC 2 (section 23.5.3) and in LC 4
(section 23.5.5).
Temperature variation (∆t) in ◦ C, used to determine the
stresses caused by temperature variation in LC 4 (section 23.5.5).

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When clicking the Database button
, the PE pipes library window appears (Figure 4.34)
in which the material quality, the Young’s modules (short and long), the allowable strengths
(short and long), the outer diameter and the wall thickness of different PE pipes can be imported.

Figure 4.34: PE pipes library window

4.6.2.2

Product Pipe Material Data for Micro tunneling
If the Micro tunneling option in the Model window (section 4.1.1) is selected, click Pipe on
the menu bar and then choose Product Pipe Material Data to open the Product Pipe Material
Data window in which the characteristics of the pipe material can be entered. Depending on
the choice between steel, synthetic and concrete (Figure 4.35), different parameters need to
be specified.

Figure 4.35: Product Pipe Material Data window, Pipe material sub-window

Steel or Concrete pipe

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Figure 4.36: Product Pipe Material Data window (Steel or Concrete pipe, Micro Tunneling
model)

Material quality
Outer diameter product
pipe (Do)
Overcut on radius
Wall thickness
Young’s modulus
Unit weight pipe material

Description of the material quality. The data in this field is
used in the report.
Outer diameter of the product pipe (Do ) in mm.
Difference between the hole radius and the outer radius of the
product pipe (lovercut ) in mm.
Wall thickness of the pipe (dn ) in mm.
Modulus of elasticity of the pipe (Eb ) in N/mm2 .
Unit weight of the pipe material (γb ) in kN/m3 . Default values
are 78.5 and 26 kN/m3 respectively for Steel and Concrete
pipe.

Synthetic pipe

Figure 4.37: Product Pipe Material Data window (Synthetic pipe, Micro tunneling model)

Material quality
Outer diameter product
pipe (Do)

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Description of the material quality. The data in this field is
used in the report.
Outer diameter of the product pipe (Do ) in mm.

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Overcut on radius
Wall thickness
Young’s modulus (short)
Young’s modulus (long)
Unit weight pipe material

4.6.3

Difference between the hole radius and the outer radius of the
product pipe (lovercut )in mm.
Wall thickness of the pipe (dn ) in mm.
Modulus of elasticity of the pipe (Eb ) at short term in N/mm2 .
Modulus of elasticity of the pipe (Eb ) at long term in N/mm2 .
Unit weight of the synthetic material (γb ) in kN/m3 . The default value is 9.54 kN/m3 .

Engineering Data
In the Pipe menu, choose the Engineering Data option to open the Engineering Data window.
The window displayed depends on the selected model.

4.6.3.1

Engineering Data for HDD
If the Horizontal directional drilling option in the Model window (section 4.1.1) is selected, the
Engineering Data window shown in Figure 4.38 is displayed in which data on the strength
calculation of the pipe can be defined (see chapter 23 for background information).

Figure 4.38: Engineering Data window (HDD)

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Standard/Advanced

Pipe filled with water on
rollers
Pipe always filled
(implosion)

Part of pipe filled with
fluid during pull back

Unit weight fluid
Bedding angle
Load angle
Relative displacement
Compression index

Linear settlement coeff.
(alpha_g) for steel
Linear settlement coeff.
(alpha_g) for PE
Modulus of subgrade
reaction of drilling
fluid (Kv)
Phi drilling fluid
Cohesion drilling fluid
Factor of friction
pipe-roller (f1)
Friction pipe-drilling
fluid (f2)
Factor of friction
pipe-soil (f3)

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Select Advanced to display and modify some of the Miscellaneous parameters (Relative displacement, Compression index, Modulus of subgrade reaction of drilling fluid, Phi drilling
fluid, Cohesion drilling fluid). If Standard is selected, then
D-G EO P IPELINE will use the default values for the five mentioned
parameters).
Mark this check-box if the pipe is filled with water on rollers.
Mark this check-box if the pipe is filled with water in all stages.
If the pipe is completely filled, the filling fluid gives an internal
fluid pressure called filling resistance pfill , see Equation 23.68 in
section 23.8.1.
Part of the cross-section of the pipe filled with fluid (Pw ) in %.
Uplift forces resulting from buoyancy of the product pipe can be
reduced by filling a part of the cross-section with water. This will
reduce the pulling force.
Unit weight of the fluid filling (γfill ).
The bedding angle β (see Figure 4.39). The default value is
120◦ .
The load angle α (see Figure 4.39). The default value is 180◦ .
Relative displacement between soil columns, necessary for full
development of friction (δd ). The default value is 10 mm.
Average compression index of the layers in which the pipe is
installed (C ). The default value for a very compressible soil sequence is 6.
Linear settlement coefficient αg for steel (average over the temperature variation ∆t). The default value for steel is 0.0000117
(mm/mm)K-1 .
Linear settlement coefficient αg for PE (average over the temperature variation ∆t). The default value for PE is 0.00018
(mm/mm)K-1 .
The modulus of subgrade reaction (also called bedding constant)
of the drilling fluid after stiffening (kv;df ). The default value is
500 kN/m3 .
Angle of internal friction of the stiffened drilling fluid (ϕdf ). The
default value is 15◦ .
Cohesion of the stiffened drilling fluid (cdf ). The default value is
5 kN/m2 .
Factor of friction between the product pipe and the rollers on the
pipe-roller (f1 ). During the pullback operation this part of the
pulling force will decrease. The default value is 0.1.
Friction between the drilling fluid and the pipeline (f2 ). The default value is 0.00005 N/mm2 .
Factor of friction between the product pipe and the soil (f3 ). The
friction between pipe and soil is influenced by buoyancy of the
pipeline in the drilling fluid. The default value is 0.2.

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Figure 4.39: Definition of the bedding angle β and the load angle α

4.6.3.2

Engineering Data for Micro tunneling
If the Micro tunneling option in the Model window (section 4.1.1) is selected, the Engineering
Data window shown in Figure 4.40 is displayed. See chapter 24 for background information.

Figure 4.40: Engineering Data window (Micro tunneling)

Standard/Advanced

Allowable thrust force
Volume loss as percentage of overcut area

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Modulus of subgrade reaction of the stiffened drilling fluid, Phi
drilling fluid, Cohesion drilling fluid). If Standard is selected, then
D-G EO P IPELINE will use the default values for the five mentioned
parameters).
The maximum allowable thrust force is usually specified by the
manufacturer of the pipe.
The volume loss determines the subsidence at the surface (i.e.
the excess soil removed by the Micro Tunneling Boring Machine).

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Relative displacement
Compression index

Modulus of subgrade
reaction of lubrification
fluid
Phi lubrication fluid
Adhesion lubrification
fluid
Factor phi for reduced
soil load
Delta lubrification fluid
Friction with injection of
lubricant
Friction without
injection of lubricant

4.6.3.3

Relative displacement between soil columns, necessary for full
development of friction (δd ). The default value is 10 mm.
Average compression index of the layers in which the pipe is
installed (C ). The default value for a very compressible soil sequence is 6.
The modulus of subgrade reaction (also called bedding constant) of the lubrification fluid (kv;lub fluid ). The default value is
500 kN/m3 .
Angle of internal friction of the lubrification fluid (ϕlub fluid ). The
default value is 15◦ .
Adhesion of the lubrification fluid (alub fluid ). The default value is
5 kN/m2 .
Safety factor applied on the reduced soil stress. The default
value is 0.5.
Delta angle of the lubrification fluid. The default value is 7.5◦ .
The friction between the soil and the pipe in case of injection
of lubricant (M ) used for the calculation of the thrust forces Fm
(see Equation 24.8 in section 24.1.4).
The friction between the soil and the pipe in case of no injection
of lubricant (M ) used for the calculation of the thrust forces Fm
(see Equation 24.8 in section 24.1.4).

Engineering Data for Construction in trench
If the Construction in trench option in the Model window (section 4.1.1) is selected, the Engineering Data window shown in Figure 4.41 is displayed. In this window, information about
the filling can be entered and will be used to determine the value of the percentage of compaction µ used in the calculation of the initial (or actual) vertical stress, see section 21.4 for
background information.

Figure 4.41: Engineering Data window (Construction in trench)

Type of fill
Compaction of fill

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Select the type of fill used for the filling of the trench: Sand, Stiff
Clay or Soft Soils.
Select the type of compaction of the filling soil: Well compacted
or Poorly compacted.

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Input

4.6.4

Drilling Fluid Data
In the Pipe menu, choose the Drilling Fluid Data option to open the Drilling Fluid Data window
in which the drill pipe and borehole dimensions, the characteristics of drilling fluid flow, and
the properties of the drilling fluid can be defined. For background information, see chapter 22.

Figure 4.42: Drilling Fluid Data window

Outer diameter pilot hole
Outer diameter pilot pipe
Outer diameter pre-ream
hole
Outer diameter drill pipe
Outer diameter borehole
Outer diameter product
pipe (Do)

Outer diameter of the hole during the pilot hole drilling [m].
Outer diameter of the pipe during the pilot hole drilling [m].
Outer diameter of the hole during the pre-reaming of the product pipeline [m].
Outer diameter of the pipe during the pre-reaming of the product pipeline [m].
Outer diameter of the hole during the pullback of the product
pipeline [m].
Outer diameter of the (bundled) pipe during the pullback of
the product pipeline. This value is automatically calculated by
the program using the pipe diameters of the different pipes
as inputted in the Product Pipe Material Data window (see
section q
4.6.2.1). The following formula is used:

Deq =

Annular back flow rate pilot
boring
Annular back flow rate prereaming
Annular back flow rate
ream and pullback
Circulation loss factor pilot
boring

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i=1

2
Do;i

Annular back flow rate (Qann ) during the pilot hole drilling, in
liter/minute.
Annular back flow rate (Qann ) during the pre-reaming stage,
in liter/minute.
Annular back flow rate (Qann ) during the pullback stage, in
liter/minute.
Circulation loss factor (floss ) during the pilot-hole drilling. The
default value is 0.3.

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Circulation loss factor prereaming
Circulation loss
factor ream and pull-back
Unit weight (γ )
Yield point (τ )
Plastic viscosity (µ)

Circulation loss factor (floss ) during the pre-reaming stage.
The default value is 0.2.
Circulation loss factor (floss ) during the pullback stage . The
default value is 0.2.
Unit weight of the drilling fluid (γdf ). The default value is
11.1 kN/m3 .
Yield point of the drilling fluid (τdf ). The default value is
0.014 kN/m2 .
Plastic viscosity of the drilling fluid (µdf ). The default value is
0.00004 kN.s/m2 .

The annular back-flow depends mainly on the size of the borehole and the pump system on
the type of drilling rig used. The circulation loss factor depends on the soil layers through
which the drilling is performed. The circulation loss factor indicates the loss of the drilling fluid
in the soil surrounding the borehole.
The properties of the drilling fluid (γdf , τdf and µdf ) can be obtained from the drilling fluid
manufacturer.
4.7
4.7.1

Defaults menu
Factors
In the Defaults menu, choose the Factor option to open the Factor input window. The content
of the window depends on the model:

Refer to section 4.7.1.1 for HDD
Refer to section 4.7.1.2 for Micro tunneling
Refer to section 4.7.1.3 for Construction in trench
4.7.1.1

Factors for HDD
If the Horizontal directional drilling option in the Model window (section 4.1.1) is selected, the
factors for loads and strength parameters according to either the Dutch standard NEN 3650
or the European standard CEN can be specified in the Factors window. Depending on the
choice of the type of material (steel or polyethylene), different factors need to be specified.
Factors for HDD – Dutch standard NEN – Polyethylene pipe
If the Dutch standard NEN was selected in the the Model window (section 4.1.1) and if a
polyethylene material was selected in the Product Pipe Material Data window (section 4.6.2.1),
the window in Figure 4.43 is displayed.

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Input

Figure 4.43: Factors window (HDD) for polyethylene pipe, acc. to the Dutch standard
NEN

Implosion at long
term
Implosion at short
term
Total unit weight

Cu/cohesion

Angle of internal
friction (Phi)
E-modulus
Pulling force

Modulus of
subgrade reaction
Soil load Qn

Pressure borehole

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Safety factor on implosion at long term (γimp;long ). The default value
is 3, as prescribed in paragraph 8.5.5.1 of NEN 3650-3 (NEN,
2012c).
Safety factor on implosion at short term (γimp;short ). The default value
is 1.5, as prescribed in paragraph 8.5.5.1 of NEN 3650-3 (NEN,
2012c).
Contingency factor on the total unit weight above and below the
phreatic level (fγ ). The default value is 1.1, as prescribed in Table
B.2 of NEN 3650-1 (NEN, 2012a).
Contingency factor on the cohesion for drained and undrained conditions (fc ). The default value is 1.4, as prescribed in Table B.2 of
NEN 3650-1 (NEN, 2012a).
Contingency factor on the angle of internal friction (fϕ ). The default value is 1.1, as prescribed in Table B.2 of NEN 3650-1 (NEN,
2012a).
Contingency factor on the Young’s modulus (fE ). The default value
is 1.25, as prescribed in Table B.2 of NEN 3650-1 (NEN, 2012a).
Contingency factor on pulling forces (f ), to take into account the
stochastic distribution in the value of the different friction components and the uncertainty on the model. The default value is 1.4, as
prescribed in paragraph E.1.2.1 of NEN 3650-1 (NEN, 2012a).
NOTE: According to the NEN 3650-1 (article E.1.2.3), the contingency factor on the pulling force for bundled pipelines should be increased to 1.8 because due to the pull back of the bundled pipelines
the risk on higher pulling forces than calculated is present.
Contingency factor on the modulus of subgrade reaction (fkv ). The
default value is 1.6.
Contingency factor on the reduced neutral soil stress Qn,r (fQn1 ),
used for the strength calculation of the pipeline (see section 23.5).
The default value is 1.1, as prescribed in Table B.3 of NEN 3650-1
(NEN, 2012a).
Contingency factor on the pressure borehole (fpress;bore ), used to
check the equilibrium between drilling fluid pressure and pore pressure, see section 22.4. The default value is 1.1.

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Bending moment
(Steel)

Bending moment
(PE)

Factor of
importance (S)
Allowable deflection
of pipe (Steel)
Piggability (Steel)

Allowable deflection
of pipe (PE)
Piggability (PE)

Unit weight water
Safety factor cover
(drained layer)

Safety factor cover
(undrained layer)

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Contingency factor on the bending moment (fM ) for steel. In paragraph E.1.3 of NEN 3650-1 (NEN, 2012a), an overall factor on bending moment (fk ) of 1.4 is prescribed. As this overall factor includes
different contingency factors (i.e. fk = fM × finstall × fR ) and as
finstall = 1.1 and fR = 1.1, a default factor of 1.15 should be inputted
for fM to get fk = 1.4 as prescribed by NEN.
Contingency factor on the bending moment (fM ) for PE. In paragraph E.1.3 of NEN 3650-1 (NEN, 2012a), an overall factor on bending moment (fk ) of 1.4 is prescribed. As this overall factor includes
different contingency factors (i.e. fk = fM × finstall × fR ) and
as finstall = 1 and fR = 1, a default factor of 1.4 should be inputted
for fM to get fk = 1.4 as prescribed by NEN.
Factor of importance (S ). The default value is 1 (for HDD), as prescribed in paragraph 6.5 of NEN 3651 (NEN, 2012d).
Maximum allowable deflection of the pipe (δ0 ). The default value
is 15% of the pipe diameter for steel, as prescribed in paragraph
11.1.5 of NEN 3651 (NEN, 2012d).
Maximum allowable deflection of the pipe for piggability (δ1 ). If this
value is exceeded, the pig (i.e. tool or vehicle that moves through
the interior of the pipeline for purposes of inspecting, dimensioning,
or cleaning) can be damaged or stuck. The default value is 5% of
the pipe diameter.
Maximum allowable deflection of the pipe (δ0 ). The default value is
8% of the pipe diameter for PE, as prescribed in paragraph 11.4.1.1
of NEN 3651 (NEN, 2012d).
Maximum allowable deflection of the pipe for piggability (δ1 ). If this
value is exceeded, the pig (i.e. tool or vehicle that moves through
the interior of the pipeline for purposes of inspecting, dimensioning,
or cleaning) can be damaged or stuck. The default value is 5% of
the pipe diameter.
Unit weight of water (γw ). The default value is 10 kN/m3 .
The ratio between the maximum allowable radius of the plastic zone
Rp;max and the soil cover H (vertical distance between the ground
level and the pipe center) for the calculation of the maximum allowable drilling fluid pressure in drained layer (i.e. sand), see Equation 22.28 in section 22.2.2. The default value is 0.5, as prescribed
in paragraph E.2.2.2 of NEN 3650-1 (NEN, 2012a): Rp,max = 0.5 H .
The ratio between the maximum allowable radius of the plastic zone
Rp;max and the soil cover H (vertical distance between the ground
level and the pipe center) for the calculation of the maximum allowable drilling fluid pressure in undrained layer (i.e. clay and peat),
see Equation 22.22 in section 22.2.1. The default value is 0.5,
as prescribed in paragraph E.2.2.2 of NEN 3650-1 (NEN, 2012a):
Rp,max = 0.5 H .
Click this button to reset all values to the default values prescribed
in the Dutch Standard NEN.
NOTE: If the input values in the Factors window differ from the default values prescribed by NEN, the value appears in red color.

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Input

Factors for HDD – Dutch standard NEN – Steel pipe
If the Dutch standard NEN was selected in the the Model window (section 4.1.1) and if a steel
material was selected in the Product Pipe Material Data window (section 4.6.2.1), the window
in Figure 4.44 is displayed. Load factors are used for the strength calculation of the pipeline
(see section 23.5).

Figure 4.44: Factors window (HDD) for steel pipe, acc. to the Dutch standard NEN

Total unit weight

Cu/cohesion

Angle of internal
friction (Phi)
E-modulus
Pulling force

Modulus of
subgrade reaction
Soil load Qn

Pressure borehole

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Contingency factor on the total unit weight above and below the
phreatic level (fγ ). The default value is 1.1, as prescribed in Table
B.2 of NEN 3650-1 (NEN, 2012a).
Contingency factor on the cohesion for drained and undrained conditions (fc ). The default value is 1.4, as prescribed in Table B.2 of
NEN 3650-1 (NEN, 2012a).
Contingency factor on the angle of internal friction (fϕ ). The default value is 1.1, as prescribed in Table B.2 of NEN 3650-1 (NEN,
2012a).
Contingency factor on the Young’s modulus (fE ). The default value
is 1.25, as prescribed in Table B.2 of NEN 3650-1 (NEN, 2012a).
Contingency factor on pulling forces (f ), to take into account the
stochastic distribution in the value of the different friction components and the uncertainty on the model. The default value is 1.4, as
prescribed in paragraph E.1.2.1 of NEN 3650-1 (NEN, 2012a).
NOTE: According to the NEN 3650-1 (article E.1.2.3), the contingency factor on the pulling force for bundled pipelines should be increased to 1.8 because due to the pull back of the bundled pipelines
the risk on higher pulling forces than calculated is present.
Contingency factor on the modulus of subgrade reaction (fkv ). The
default value is 1.6.
Contingency factor on the reduced neutral soil stress Qn,r (fQn1 ),
used for the strength calculation of the pipeline (see section 23.5).
The default value is 1.1, as prescribed in Table B.3 of NEN 3650-1
(NEN, 2012a).
Contingency factor on the pressure borehole (fpress;bore ), used to
check the equilibrium between drilling fluid pressure and pore pressure, see section 22.4. The default value is 1.1.

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Bending radius

Bending moment
(Steel)

Bending moment
(PE)

Design pressure
Design pressure
(combination)
Test pressure
Installation
Soil load Qn
Temperature

Traffic load factor
Factor of
importance (S)
Allowable deflection
of pipe (Steel)
Piggability (Steel)

Allowable deflection
of pipe (PE)
Piggability (PE)

Unit weight water

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Contingency factor on the bending radius (fR ) used for the determination of the axial stress in the strength calculation, see section 23.5. The default value is 1.1.
Contingency factor on the bending moment (fM ) for steel. In paragraph E.1.3 of NEN 3650-1 (NEN, 2012a), an overall factor on bending moment (fk ) of 1.4 is prescribed. As this overall factor includes
different contingency factors (i.e. fk = fM × finstall × fR ) and as
finstall = 1.1 and fR = 1.1, a default factor of 1.15 should be inputted
for fM to get fk = 1.4 as prescribed by NEN.
Contingency factor on the bending moment (fM ) for PE. In paragraph E.1.3 of NEN 3650-1 (NEN, 2012a), an overall factor on bending moment (fk ) of 1.4 is prescribed. As this overall factor includes
different contingency factors (i.e. fk = fM × finstall × fR ) and
as finstall = 1 and fR = 1, a default factor of 1.4 should be inputted
for fM to get fk = 1.4 as prescribed by NEN.
Load factor on the design pressure (fpd ). The default value is 1.25
as prescribed in Table 2 of NEN 3650-2 (NEN, 2012b).
Load factor on the design pressure when used in combination
(fpd;comb ). The default value is 1.15 as prescribed in Table 2 of
NEN 3650-2 (NEN, 2012b).
Load factor on the test pressure (fpt ). The default value is 1.1 as
prescribed in Table 2 of NEN 3650-2 (NEN, 2012b).
Load factor on the installation (finstall ). The default value is 1.1 as
prescribed in Table 2 of NEN 3650-2 (NEN, 2012b).
Load factor on the reduced neutral soil stress Qn,r (fQn2 ). The default value is 1.5.
Load factor on the stress due to temperature variation (ftemp ). The
default value is 1.1 as prescribed in Table 2 of NEN 3650-2 (NEN,
2012b).
The load factor on the traffic load fqv , see section 21.14. The default
value is 1.35, as prescribed in Table 2 of NEN 3650-2 (NEN, 2012b).
Factor of importance (S ). The default value is 1 (for HDD), as prescribed in paragraph 6.5 of NEN 3651 (NEN, 2012d).
Maximum allowable deflection of the pipe (δ0 ). The default value
is 15% of the pipe diameter for steel, as prescribed in paragraph
11.1.5 of NEN 3651 (NEN, 2012d).
Maximum allowable deflection of the pipe for piggability (δ1 ). If this
value is exceeded, the pig (i.e. tool or vehicle that moves through
the interior of the pipeline for purposes of inspecting, dimensioning,
or cleaning) can be damaged or stuck. The default value is 5% of
the pipe diameter.
Maximum allowable deflection of the pipe (δ0 ). The default value is
8% of the pipe diameter for PE, as prescribed in paragraph 11.4.1.1
of NEN 3651 (NEN, 2012d).
Maximum allowable deflection of the pipe for piggability (δ1 ). If this
value is exceeded, the pig (i.e. tool or vehicle that moves through
the interior of the pipeline for purposes of inspecting, dimensioning,
or cleaning) can be damaged or stuck. The default value is 5% of
the pipe diameter.
Unit weight of water (γw ). The default value is 10 kN/m3 .

Deltares

Input

Safety factor cover
(drained layer)

Safety factor cover
(undrained layer)

The ratio between the maximum allowable radius of the plastic zone
Rp;max and the soil cover H (vertical distance between the ground
level and the pipe center) for the calculation of the maximum allowable drilling fluid pressure in drained layer (i.e. sand), see Equation 22.28 in section 22.2.2. The default value is 0.5, as prescribed
in paragraph E.2.2.2 of NEN 3650-1 (NEN, 2012a): Rp,max = 0.5 H .
The ratio between the maximum allowable radius of the plastic zone
Rp;max and the soil cover H (vertical distance between the ground
level and the pipe center) for the calculation of the maximum allowable drilling fluid pressure in undrained layer (i.e. clay and peat),
see Equation 22.22 in section 22.2.1. The default value is 0.5,
as prescribed in paragraph E.2.2.2 of NEN 3650-1 (NEN, 2012a):
Rp,max = 0.5 H .
Click this button to reset all values to the default values prescribed
in the Dutch Standard NEN.
NOTE: If the input values in the Factors window differ from the default values prescribed by NEN, the value appears in red color.

Factors for HDD – European standard CEN – Polyethylene pipe
If the European standard CEN was selected in the the Model window (section 4.1.1) and if a
polyethylene material was selected in the Product Pipe Material Data window (section 4.6.2.1),
the window in Figure 4.45 is displayed.

Figure 4.45: Factors window (HDD) for polyethylene pipe, acc. to the European standard
CEN

For the definition of the parameters refer to the window for the Dutch standard NEN (see
Figure 4.43), only the default values are different.
Click the
button to reset all values to the default values prescribed in the European
standard CEN. If the input values in the Factors window differ from the default values prescribed by CEN, the value appears in red color.

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Factors for HDD – European standard CEN – Steel pipe
If the European standard CEN was selected in the the Model window (section 4.1.1) and if a
steel material was selected in the Product Pipe Material Data window (section 4.6.2.1), the
window in Figure 4.46 is displayed.

Figure 4.46: Factors window (HDD) for steel pipe, according to the European standard
CEN

For the definition of the parameters refer to the window for the Dutch standard NEN (see
Figure 4.44), only the default values are different.
button to reset all values to the default values prescribed in the European
Click the
standard CEN. If the input values in the Factors window differ from the default values prescribed by CEN, the value appears in red color.
4.7.1.2

Factors for Micro tunneling
If the Micro tunneling option in the Model window (section 4.1.1) is selected, the Factors
window of Figure 4.47 is displayed in which the safety factors for soil parameters can be
specified.

Figure 4.47: Factors window (Micro tunneling)

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Input

Cu/cohesion

Angle of internal
friction (Phi)
Horizontal effective
stress
Safety factor water
pressure
Safety factor uplift
Contingency factor soil
cover
Overburden factor silo
effect
Stability ratio N

Unit weight water

4.7.1.3

The safety factor on the cohesion for drained and undrained conditions (fc ). The default value is 1.4, as prescribed in Table B.2
of NEN 3650-1 (NEN, 2012a).
The safety factor on the angle of internal friction (fϕ ). The default
value is 1.1, as prescribed in Table B.2 of NEN 3650-1 (NEN,
2012a).
The safety factor on the horizontal effective stress (fσh ). The
default value is 1.5.
The safety factor on the water pressure u (fu ). The default value
is 1.05.
The safety factor on uplift (fuplift ). The default value is 1.
The contingency factor on soil cover (fcover ). The default value is
1.1.
The overburden factor on silo effect (fsilo ). The default value is
2.
The stability ratio (N ). The default value is 3. This ratio is used
for the calculation of the minimal support pressure in undrained
conditions, see Equation 24.2 in section 24.1.2.
The unit weight of water (γw ). The default value is 10 kN/m3 .
Click this button to reset all values to the default values.
NOTE: If the input values in the Factors window differ from the
default values, the value appears in red color.

Factors for Construction in trench
If the Construction in trench option in the Model window (section 4.1.1) is selected, the Factors
window of Figure 4.48 is displayed in which the safety factor for uplift and the unit weight of
water can be specified.

Figure 4.48: Factors window (Construction in trench)

Safety factor uplift
Safety factor hydraulic
heave
Unit weight water

Deltares

The safety factor on uplift (fuplift ). The default value is 1.
The safety factor on hydraulic heave (fburst ). The default value is
1.
Unit weight of water (γw ). The default value is 10 kN/m3 .
Click this button to reset all values to the default values.
NOTE: If the input values in the Factors window differ from the
default values, the value appears in red color.

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4.7.2

Special Stress Analysis
If the Horizontal directional drilling option in the Model window (section 4.1.1) is selected,
the Special Stress Analysis window of Figure 4.49 is displayed when selecting Special Stress
Analysis from the Defaults menu. In this window, it is possible to choose between three types
of stress analysis: a standard, a per vertical or a special analysis, as explained below.

Figure 4.49: Special Stress Analysis window (HDD)

Stress analysis options

Three types of stress analysis are available:
• A Standard stress analysis, performed from the Start option
of the Calculation menu (see section 5.1), which uses the maximum reduced neutral soil stress and the maximum modulus of
subgrade reaction of the soil calculated by D-G EO P IPELINE between all the verticals and the minimum bending radius present
in the pipeline configuration.
• A stress analysis Per vertical, performed from the Start option of the Calculation menu (see section 5.1), which uses the
reduced neutral soil stress and the modulus of subgrade reaction of the soil calculated by D-G EO P IPELINE per vertical and the
bending radius of the pipeline trajectory cut by the vertical.
NOTE: If the vertical cut a straight part of the pipeline trajectory, D-G EO P IPELINE assumes a very large bending radius of
100000 m.
• A “Special Stress Analysis”, performed from the Special Stress
Analysis option of the Calculation menu (see section 5.2) using
Stress calculation data (i.e user-defined values for the reduced
neutral soil stress, for the modulus of subgrade reaction of the
soil and for the bending radius).

If the option Use stress calculation data is selected, the following values must be inputted:
Soil load (neutral or
reduced neutral) Qn
raised by a traffic load
if any
Modulus of subgrade
reaction

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Enter the user-defined reduced neutral soil stress (in kN/m2 ),
used for a Special Stress Analysis (section 5.2).

Enter the user-defined modulus of subgrade reaction of the soil
(in kN/m3 ), used for a Special Stress Analysis (section 5.2).

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Input

Radius

Deltares

Radius of the pipeline in the ground, which is used for the calculation of the pulling force. During a standard calculation,
D-G EO P IPELINE assumes the maximum present radius. With
the Special Stress Analysis (section 5.2), an other radius can
be chosen by the user.

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5 Calculations
Start Calculation
On the menu bar, click Start in the Calculation menu to perform the following calculations:

Calculation of soil mechanical data
The passive, neutral and reduced vertical stresses of the soil, the vertical coefficient of
subgrade reaction, and the ultimate bearing capacity for each vertical are calculated and
written to a report file (see section 6.2.4). For background information, see chapter 21].

Calculation of drilling fluid pressures (only for HDD)

In directional drilling first a bore hole is made by a pilot drilling. This bore hole has
a relatively small diameter. During the second drilling stage the initial bore hole is
enlarged by pre-reaming. When the requested diameter is reached the product pipe
is pulled into the bore hole. During all drilling stages a minimum required drilling fluid
pressure is necessary. The bore fluid pressure induces a return flow of drilling fluid
from the drilling head to the entry or exit point. The return flow transports loosened soil
material. The necessary fluid pressure depends on:
The difference in elevation between the bore hole and the exit point of the return
flow;

5.1

The minimum required pressure necessary to cause a return flow (soil material
included) over a certain distance.

When the entry and exit points are not on the same level, the minimum required drilling
fluid pressure depends on the direction of the drilling (from left to right or from right to
left). D-G EO P IPELINE calculates the minimum required drilling fluid pressure for both
cases.
The maximum allowable pressure depends on the strength of the soil around the borehole. When the required drilling pressure is higher than the maximum allowable pressure, there is a risk a blow out may occur. In that case, the pipeline configuration must
be changed. For instance, by choosing a lower pipe level or by moving the entry or exit
point.
The calculations of the minimum and maximum drilling fluid pressures for the three
stages (pilot, pre-ream and pull-back) are performed in the user defined verticals. The
results of the calculations are written to a report file (see section 6.2.1). For background
information, see chapter 22.

Pipe stress analysis (only for HDD)
In the pipe stress analysis, the pulling forces during the pull-back operation, the maximum acting stresses in the pipe material and the deflection of the pipeline are calculated. The calculated stresses are compared to the allowable short and long term
stresses for a PE pipeline, while for a steel pipeline a total stress is calculated and
compared with the allowable stress. With this option, the strength calculation is performed with the calculated reduced neutral soil load and bedding constant after the
soil mechanical data has been calculated. The results of the calculations are written
to a report file (see section 6.2.5 and section 6.2.6). For background information, see
chapter 23.

Settlements
The settlements of soil layers below the pipeline are calculated. For Micro Tunneling
model, the subsidence are also calculated. The results of the calculations are written
to a report file (see section 6.2.2 and section 6.2.3). For background information, see
section 21.10 and section 24.3.

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the uplift check and the hydraulic heave check for Trenching; for background information, see chapter 25.

Operation parameters

the uplift check, the face support pressures and the thrust forces for Micro tunneling; for background information, see section 24.1 and section 24.2.

The results of the calculations are written to a report file (see section 6.2.7 and section 6.2.8).
5.2

Special Stress Analysis (only for HDD)
On the menu bar, click Special Stress Analysis in the Calculation menu to perform a pipe
stress calculation with the user-defined values for the reduced neutral soil stress, the modulus
of subgrade reaction and the bending radius, specified in the Special Stress Analysis window
(section 4.7.2) instead of the calculated values. D-G EO P IPELINE will not apply safety factors
on those three specified values, assuming they are already included. A special stress analysis
must always be started separately.

5.3
5.3.1

Warning and Error messages
Warning messages
Before calculation, warning messages might be displayed in the Warning window after starting
the calculation. The calculation will be paused. If clicking Yes the calculations will continue,
whereas if clicking No the calculations will be aborted. Figure 5.1 gives an example of warning
messages displayed when an undrained layer has an undrained cohesion cu of 0 and when
determining the allowable curve radius in accordance with section 20.1.4.

Figure 5.1: Warning window (before calculation) about allowable radius

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Calculations

5.3.2

Error messages
If errors are found in the input, no calculation can be performed and D-G EO P IPELINE opens
the Error Messages window displaying more details about the error(s). Those errors must be
corrected before performing a new calculation. To view those error messages, select the Error
Messages option from the Help menu (section 3.3.1). They are also writing in the *.err file.
They will be overwritten the next time a calculation is started.

Figure 5.2: Error Messages window

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6 View Results
6.1

Report selection
On the menu bar, click Results and then choose Report Selection to open the corresponding
input window in which the content of the final report can be selected.

Figure 6.1: Report Selection window

6.2

Report
On the menu bar, click Results and then choose Report to open the Report window displaying
the selected results (section 6.1) of the calculation. This window displays the contents of the
ASCII file with extension ‘.drd’.
Click the Print active window button

on the icon bar to print the report.

Use the Export Report option in the File menu to export the report in RTF, PDF, TXT or HTML
format.
The report has its own toolbar:
Those four buttons enable the user to zoom in, to zoom out,
to zoom the full page or to zoom the page width.
Those four buttons enable the user to browse through the
report by respectively moving to first page, moving to previous
page, moving to next page or moving to last page.
Another way of quickly browsing through the report is by entering a page number in the input field on the toolbar and
pressing the Enter key.

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The output file consists of:

First page
Date and time of report
File name
Project identification (as inputted in section 4.1.2)

Table of Contents
Input Data chapter gives an echo of the input
Drilling Fluid Pressures chapter gives the results (plots and tables) of the drilling fluid
pressures calculation for the three stages of the HDD technique (section 6.2.1)

Deformations chapter gives:
the settlements of soil layers below the pipeline (section 6.2.2)
the subsidence for Micro Tunneling model (section 6.2.3)

Soil mechanical parameters chapter which gives the soil mechanical data (section 6.2.4)
Data for Stress analysis chapter includes buoyancy control and pulling forces calculation of the HDD technique (section 6.2.5)

Stress analysis chapter gives the stress results for the 5 load combinations (1A, 1B, 2,
3 and 4) of the HDD technique (section 6.2.6)

Operation Parameters chapter gives:
the uplift check and the hydraulic heave check for Trenching (section 6.2.7)
the uplift check, the face support pressures and the thrust forces for Micro Tunneling (section 6.2.8)

The following sections describe the output in more detail. The calculation process can be
aborted, after which a message is appended to the output file and the file is closed. All results
until the moment the calculation was stopped remain in the file.
6.2.1

Report – Drilling Fluid Pressure

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6.2.1.1

Report – Drilling Fluid Data
In the Drilling Fluid Data section, the results of the drilling fluid pressures calculation for the
three stages (pilot hole drilling, pre-reaming of the borehole and pullback of the product pipe)
are displayed.

Figure 6.2: Report window, Drilling Fluid Data section

The following is an explanation of the column headings:
Vertical nr.
Max, deformation
Max, soil cover

[-]
[kN/m2 ]

Number of the calculation vertical.
Maximum drilling fluid pressure: refer to Equation 22.28 in
section 22.2.2 for drained layers and to Equation 22.22 in
section 22.2.1 for undrained layers.
For drained layers, the determination of the maximum allowable radius of the plastic zone (Rp;max ), can be related:
either to the
sdeformation of the bore hole:

Rb2
× 2εg;max ;
Q
or to the soil cover: Rp;max = 0.5 H
Rp;max =

Min,left

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[kN/m ]

(Refer to section 22.2 for the definition of the parameters.)
Minimum drilling fluid pressure assuming that the drilling
of the pilot is from left to right (see section 22.1 for background information).

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[kN/m2 ]

Min,right

6.2.1.2

Minimum drilling fluid pressure assuming that the drilling
of the pilot is from right to left (see section 22.1 for background information).

Report – Equilibrium between Drilling Fluid Pressure and Pore Pressure
In the Equilibrium between Drilling Fluid Pressure and Pore Pressure section, the static drilling
fluid p1 is calculated and compared with the calculated pore pressure u, for each vertical. The
ratio p1 /u yields the safety factor, which should be higher than the (user-defined) requested
safety factor.

Figure 6.3: Report window, Equilibrium between Drilling Fluid Pressure and Pore Pressure section

The following is an explanation of the column headings:
Vertical nr.
Drilling fluid

[-]
[kN/m2 ]

Water

[kN/m2 ]

Safety

[-]

Result

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Number of the calculation vertical.
Static column pressure of the drilling fluid (p1 ), see Equation 22.2 in section 22.4.
Calculated pore pressure u, see Equation 26.4 in section 26.5.
Calculated safety factor: ratio between the static drilling fluid
pressure and the pore pressure.
If the calculated safety factor is higher than the required safety
factor, then the drilling fluid pressure is Sufficient, otherwise it
is Not sufficient.
NOTE: The required safety factor is defined in the Factors
window under the field Contingency factor – Pressure borehole, see section 4.7.1.1.

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6.2.2

Report – Settlements of soil layers below the pipeline
This section is available only if the Use settlement option in the Model window (section 4.1.1)
has been selected before performing a calculation.

Figure 6.4: Report window, Settlements of soil layers below the pipeline section

The following is an explanation of the column headings:

6.2.3

Vertical nr.
Settlement

[-]
[mm]

Additional
settlement
dv

[mm]
[mm]

Number of the calculation vertical.
Settlement calculated with the selected model, Koppejan or Isotache (section 4.1.1). For background information, see section 21.10.
Additional settlement as inputted in the Calculation Verticals window (section 4.4.2).
Total settlement (sum of the Settlement and the Additional settlement columns).

Report – Subsidence
This section is available only if the Micro tunneling option in the Model window (section 4.1.1)
has been selected. Due to the overcut surface subsidence occurs. Subsidence is calculated
for each vertical at different horizontal distances of the z -axis (i.e. 0 until 3 W , where W is the
vertical distance between the surface level and the pipe center). For background information,
refer to Equation 24.14 in section 24.3. Results are given in tables and in graphs.

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Figure 6.5: Report window, Subsidence section

6.2.4

Report – Soil Mechanical Data
Depending on the selected model in the Model window section 4.1.1, the soil mechanical
parameters are different.

6.2.4.1

Soil Mechanical Parameters for HDD

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Figure 6.6: Report window – Soil Mechanical Parameters section (for HDD)

The following is an explanation of the column headings:
Vertical nr.
Pv;p
Pv;n
Ph;n

[-]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]

Pv,r;n

[kN/m2 ]

kv;top

[kN/m3 ]

dv
kv

[mm]
[kN/m3 ]

Pv;e
kh

[kN/m2 ]
[kN/m3 ]

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Number of the calculation vertical.
Passive soil load (see Equation 21.2 in section 21.2).
Neutral vertical soil load (see Equation 21.1 in section 21.1).
Neutral horizontal soil load (see Equation 21.12 in section 21.5.1).
Reduced neutral soil load (see Equation 21.4 and Equation 21.8
in section 21.3).
Vertical modulus of subgrade reaction at the top of the pipe (see
Equation 21.14 in section 21.6.1).
Vertical displacement (see section 21.10).
Vertical modulus of subgrade reaction at the bottom of the pipe
(see Equation 21.14 in section 21.6.1).
Vertical bearing capacity (see Equation 21.26 in section 21.8).
Horizontal modulus of subgrade reaction (see Equation 21.24 in
section 21.7.1).

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6.2.4.2

Ph;e

[kN/m2 ]

tmax
dmax

[kN/m2 ]
[mm]

Horizontal bearing capacity (see Equation 21.28 in section 21.9.1).
Maximal axial friction along the pipeline (see section 21.11.1).
Displacement necessary to develop the maximal axial friction
along the pipeline (see section 21.12.1).

Soil Mechanical Parameters for Micro tunneling

Figure 6.7: Report window – Soil Mechanical Parameters section (for Micro tunneling)

The following is an explanation of the column headings:
Vertical nr.
Pv;p
Pv;n
Ph;n

[-]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]

Pv,r;n
kv;top

[kN/m2 ]
[kN/m3 ]

[mm]

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6.2.4.3

[kN/m3 ]

Pv;e
kh

[kN/m2 ]
[kN/m3 ]

Ph;e

[kN/m2 ]

tmax

[kN/m2 ]

dmax
mat

[mm]
[-]

Vertical modulus of subgrade reaction downward (see Equation 21.14 in section 21.6.1).
Vertical bearing capacity (see Equation 21.26 in section 21.8).
Horizontal modulus of subgrade reaction (see Equation 21.24 in
section 21.7.1).
Horizontal bearing capacity (see Equation 21.29 in section 21.9.2).
Maximal axial friction along the pipeline (see Equation 21.52 in
section 21.11.2).
Displacement at maximal friction (see section 21.12.2).
The corresponding type of material (see section 21.13).

Soil Mechanical Parameters for Construction in trench

Figure 6.8: Report window – Soil Mechanical Parameters section (for Construction in
trench)

The following is an explanation of the column headings:
Vertical nr.
Pv;p
Pv;n
Ph;n

[-]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]

Pv;a

[kN/m2 ]

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6.2.5

kv;top1

[kN/m3 ]

kv;top2

[kN/m3 ]

dv
kv1

[mm]
[kN/m3 ]

kv2

[kN/m3 ]

Pv;e
kh

[kN/m2 ]
[kN/m3 ]

Ph;e

[kN/m2 ]

tmax

[kN/m2 ]

dmax
mat

[mm]
[-]

Vertical modulus of subgrade reaction upward (see section 21.6.2).
Vertical modulus of subgrade reaction upward (see section 21.6.2).
Vertical displacement (see section 21.10).
Vertical modulus of subgrade reaction downward of the first and
second branch (see section 21.6.2).
Vertical modulus of subgrade reaction downward of the first and
second branch (see section 21.6.2).
Vertical bearing capacity (see Equation 21.26 in section 21.8).
Horizontal modulus of subgrade reaction (see Equation 21.25 in
section 21.7.2).
Horizontal bearing capacity (see Equation 21.29 in section 21.9.2).
Maximal axial friction along the pipeline (see Equation 21.52 in
section 21.11.2).
Displacement at maximal friction (see section 21.12.2).
The corresponding type of material (see section 21.13).

Report – Data for Stress Analysis
Buoyancy Control
The magnitude of the pulling force is caused in part by friction between the soil around the
borehole and the product pipe. In turn, the magnitude of the friction is dependent on the
degree of buoyancy of the pipeline in the drilling fluid. Uplift forces resulting from buoyancy
can be neutralized by filling the pipeline with water. The optimum volume of water placed in
the pipeline provides the most advantageous distribution of buoyant forces. If the resulting
force is a positive value, the pipeline will move upwards. If the resulting force is a negative
value the pipeline will move downwards.

Figure 6.9: Report window, Buoyancy Control section

The following is an explanation of the content:
Uplift forces
Weight of pipeline
(including filling)
Resulting

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Weight of the drilling fluid in kg/m (see Equation 23.1 in section 23.1).
Weight of the pipeline filled with water in kg/m (see Equation 23.4
in section 23.1).
Effective weight of the pipeline in kg/m (see Equation 23.5 in
section 23.1).

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See section 23.1 for background information on buoyancy control.
Calculation pulling forces
This part of the report displays the calculated pulling forces (without applying a contingency
factor), for characteristic locations along the drilling line. In a case without horizontal bending,
six characteristic points are calculated. Their location is given in Figure 6.11. In case of
horizontal bending, the beginning and ending points of each horizontal bending will be defined
as characteristic points.

Figure 6.10: Report window, Calculation pulling force section

The following is an explanation of the column headings:
Characteristic points
Length pipe in borehole
Expected pulling force

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Points at different locations along the drilling line (see Figure 6.11). T1 and T6 are the entry and exit points, respectively.
Length of the pipe between the entry point and the characteristic
point.
Calculated pulling forces without using a contingency factor (see
Equation 23.6 in section 23.2).

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entry point

exit point
ground level
T6

T5
T2

Figure 6.11: Locations of the characteristic points T1 to T6

6.2.6
6.2.6.1

Report – Stress Analysis
Stress Analysis HDD
Load Combination 1A: Start pull-back operation
This part of the report displays the calculated axial and tangential stresses at the start of the
pull-back operation. See section 23.5.1 for background information.

Figure 6.12: Report window, Stress analysis for load combination 1A

Sigma_b
Sigma_t
Sigma_a,max

Axial bending stress in N/mm2 , see Equation 23.23.
Axial stress due to friction of the pipeline on the roller-lane, in N/mm2 ,
see Equation 23.25.
Maximum axial stress in N/mm2 , see Equation 23.26.

Load Combination 1B: End pull-back operation
This part of the report displays the calculated axial and tangential stresses at the end of the
pullback operation. See section 23.5.2 for background information.

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Figure 6.13: Report window, Stress analysis for load combination 1B

Sigma_b
Sigma_t
Sigma_a,max
Lambda
qr
Sigma_qr
Sigma_t,max

Axial bending stress in N/mm2 , see Equation 23.27.
Axial stress due to pull-back in N/mm2 , see Equation 23.28.
Maximum axial stress in N/mm2 , see Equation 23.29.
Characteristic stiffness between the pipeline and the soil in mm−1 , see
Equation 23.13.
Soil reaction in N/mm2 , see Equation 23.11.
Stress due to soil reaction in N/mm2 , see Equation 23.31.
Maximum tangential stress in N/mm2 , see Equation 23.32.

Load Combination 2: Application internal pressure
This part of the report displays the calculated stresses when the internal pressure is applied.
See section 23.5.3 for background information.

Figure 6.14: Report window, Stress analysis for load combination 2

Sigma_py
Sigma_px
Sigma_ptest

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Internal stress due to design pressure in N/mm2 , see Equation 23.33
for thin pipe and Equation 23.35 for thick pipe.
Internal axial stress due to design pressure in N/mm2 , see Equation 23.37.
Internal stress due to test pressure in N/mm2 , see Equation 23.34 for
thin pipe and Equation 23.36 for thick pipe.

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Load Combination 3: In operation (situation without pressure)
This part of the report displays the calculated axial and tangential stresses when the pipe is
in operation without internal pressure. See section 23.5.4 for background information.

Figure 6.15: Report window – Stress analysis for load combination 3

Sigma_b
Sigma_a,max
Sigma_qr
Sigma_qn
Sigma_t,max

Axial bending stress in N/mm2 , see Equation 23.38.
Maximum axial stress in N/mm2 , see Equation 23.39.
Stress due to soil reaction in N/mm2 , see Equation 23.40.
Stress due to reduced vertical load in N/mm2 , see Equation 23.41.
Maximum tangential stress in N/mm2 , see Equation 23.42.

Load Combination 4: In operation (with internal pressure)
This part of the report displays the calculated axial and tangential stresses when the pipe is
in operation with internal pressure. See section 23.5.5 for background information.

Figure 6.16: Report window, Stress analysis for load combination 4

Sigma_b
Sigma_py

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Axial bending stress in N/mm2 , see Equation 23.43.
Ring stress due to internal design pressure in N/mm2 , see Equation 23.44.

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Sigma_px
Sigma_ptest
Sigma_Temp
Sigma_a,max
Sigma_qr
Sigma_qn
Frr
Frr’
Sigma_t,max

Axial stress due to internal design pressure in N/mm2 , see Equation 23.47.
Ring stress due to internal test pressure in N/mm2 , see Equation 23.45
for steel and Equation 23.46 for PE.
Axial stress due to temperature variation in N/mm2 , see Equation 23.48.
Maximum axial stress in N/mm2 , see Equation 23.49.
Stress due to soil reaction in N/mm2 , see Equation 23.50.
Stress due to reduced vertical load in N/mm2 , see Equation 23.51.
Direct re-rounding factor in N/mm2 , see Equation 23.53.
Indirect re-rounding factor in N/mm2 , see Equation 23.54.
Maximum tangential stress in N/mm2 , see Equation 23.52.

Check on calculated stresses (Steel)
This part of the report displays a table in which the calculated combined stresses of the different load combinations are compared to the maximum allowable stress (see section 23.6.1.1
for background information).

Figure 6.17: Report window, Check on calculated stresses section (steel pipe)

Check on calculated stresses (PE)
This part of the report displays a table in which the calculated combined stresses of the different load combinations are compared to the maximum allowable stress (see section 23.6.1.2
for background information).

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Figure 6.18: Report window, Check on calculated stresses section (PE pipe)

Check on deflection
This part of the report displays the calculated deflection of the pipeline and compares it to the
maximum allowable deflection (see section 23.7 for background information).

Figure 6.19: Report window, Check on deflection section

Check for implosion (only for PE pipe)
This calculation is performed only for a polyethylene pipe. The maximum allowable external
pressure is calculated (see section 23.8 for background information) in the short and long term
for the pullback operation (Stage 2) and the pipeline in operation (Stage 3a), respectively.

Figure 6.20: Report window, Check for implosion section

6.2.7

Report – Operation Parameters (Trenching)

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Uplift Check
Due to buoyancy of an empty pipeline below the groundwater table, the uplift should be
checked. Results are given per vertical in a table (Figure 6.21) and in graphs.

Figure 6.21: Report window, Uplift Check section

Vertical nr.
Safety factor
calculated
Safety factor
required

[-]
[-]
[-]

Number of the calculation vertical.
The calculated safety factor for uplift, see Equation 25.5 in section 25.1.
The required safety factor for uplift as specified by the user in the
Factors window (section 4.7.1.3).

Hydraulic Heave Check
In case of trenching in soil layers which cover an aquifer with high pore pressures, bursting of
the bottom of the trench can be an installation risk which needs to be checked. Results are
given per vertical in a table (Figure 6.22) and in graphs.

Figure 6.22: Report window, Hydraulic Heave Check section

Vertical nr.
Safety factor
calculated

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[-]
[-]

Number of the calculation vertical.
The calculated safety factor for hydraulic heave, see Equation 25.7 in section 25.2.

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Safety factor
required

6.2.8

[-]

The required safety factor for hydraulic heave as defined by the
user in the Factors window (section 4.7.1.3).

Report – Face Support Pressures and Thrust Forces (Micro tunneling)
Results are given per vertical in a table (Figure 6.23) and in graphs.

Figure 6.23: Report window, Operation Parameters section for Micro tunneling

The following is an explanation of the column headings:
Vertical nr.
Pmax

[-]
[kN/m2 ]

Pmin

[kN/m2 ]

Pneutral

[kN/m2 ]

Thrust
Forces

[kN]

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Number of the calculation vertical.
Pmax is the maximum allowable face support pressure which
should not be exceeded in order to prevent the following possible failure mechanisms:
Soil failure due to pushing a soil wedge in upward direction
A blow out to the surface due to hydraulic fracturing
Horizontal hydraulic fracturing at the transition of soil layers.
Refer to Equation 24.7 in section 24.1.3.
Pmin is the minimum face support pressure required for stable
conditions of the soil adjacent to the micro tunneling machine. Refer to Equation 24.2 for undrained layers and to Equation 24.4 for
drained layers, in section 24.1.2.
Pneutral is the target pressure, i.e. the total neutral horizontal soil
pressure. Refer to Equation 24.1 in section 24.1.1.
The thrust force is the force required to install a micro tunnel or
pipeline in between the launch pit and the reception pit. Thrust
forces are calculated in both cases: injection of lubricant (Lubricated) or not (Normal). Refer to Equation 24.8 in section 24.1.4.

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6.3

Drilling Fluid Pressures Plots
Only available if the Horizontal directional drilling model in the Model window (section 4.1) is
selected. In the Results menu, choose the Drilling Fluid Pressures Plots option to display the
following plots for the three boring stages (pilot, pre-ream and pullback):
——-

Maximum allowable drilling fluid pressure (plastic zone related to deformation bore hole)
Refer to Equation 22.28 in section 22.2.2 for drained layers and to Equation 22.22
in section 22.2.1 for undrained layers. For drained layers, the determination of the
maximum allowable radius of the plastic zone Rp;max is related to the deformation
of the bores
hole:

Rp;max =
−·−

Rb2
× 2εg;max
Q

Maximum allowable drilling fluid pressure (plastic zone related to soil cover)
Refer to Equation 22.28 in section 22.2.2 for drained layers and to Equation 22.22
in section 22.2.1 for undrained layers. For drained layers, the determination of the
maximum allowable radius of the plastic zone is related to the soil cover:

Rp;max = 0.5 H
−−− Minimum drilling fluid pressure assuming that the pilot is drilled from the
-----

left side to the right side
Refer to section 22.1 for background information.
Minimum drilling fluid pressure assuming that the pilot is drilled from the
right side to the left side
Refer to section 22.1 for background information.

To select the stage, click on one of the three tabs of the Drilling Fluid Pressures Plots window
(Figure 6.24): Pilot, Prereaming or Reaming and pullback operation.

Figure 6.24: Drilling Fluid Pressures Plots window

Use the Pan

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and Zoom

buttons to select the part to be viewed in detail.

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6.4

Operation Parameter Plots
In the Results menu, choose the Operation Parameter Plots option. The content of the Operation Parameter Plots window depends on the selected model:

Refer to section 6.4.1 for Micro tunneling;
Refer to section 6.4.2 for Construction in trench.
6.4.1

Operation Parameter Plots for Micro Tunneling
For Micro tunneling model, the Operation Parameter Plots window displays three different
plots by clicking on one of the three tabs:

the face support pressures at the micro tunneling machine (Figure 6.25);
the thrust pressures along the micro tunnel or pipe segments (Figure 6.26);
the uplift safety factor along the micro tunneling (Figure 6.27).
Use the Pan

and Zoom

buttons to select the part to be viewed in detail.

For background information, refer to chapter 24.

Figure 6.25: Operation Parameter Plots window, Face support pressures tab

Maximum face support
pressure

Neutral pressure

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The maximum allowable face support pressure which should not
be exceeded in order to prevent the following possible failure
mechanisms:
Soil failure due to pushing a soil wedge in upward direction
A blow out to the surface due to hydraulic fracturing
Horizontal hydraulic fracturing at the transition of soil layers.
For background information, refer to section 24.1.3.
The neutral pressure is the pressure with the lowest soil deformation, i.e. the total neutral horizontal soil pressure. For background information, refer to section 24.1.1.

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Minimum face support
pressure

The minimum face support pressure is the pressure required for
stable conditions of the soil adjacent to the micro tunneling machine. For background information, refer to section 24.1.2.

Figure 6.26: Operation Parameter Plots window, Thrust pressures tab

Thrust force lubricated

Thrust force not
lubricated

Maximum allowable
thrust force

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The thrust force lubricated is the force required to install a micro
tunnel in between the launch pit and the reception pit in case of
injection of lubricant. For background information, refer to section 24.1.4.
The thrust force lubricated is the force required to install a micro
tunnel in between the launch pit and the reception pit in case
of no injection of lubricant. For background information, refer to
section 24.1.4.
The maximum allowable thrust force is usually given by the manufacturer of the pipe and specified in the Engineering Data window (section 4.6.3).

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Figure 6.27: Operation Parameter Plots window, Safety uplift tab

6.4.2

Operation Parameter Plots for Construction in trench
For Construction in trench model, the Operation Parameter Plots window displays two different
plots by clicking on one of the two tabs:

the safety factor for uplift along the bottom of the trench (Figure 6.28);
the safety factor for hydraulic heave along the bottom of the trench (Figure 6.30);

Figure 6.28: Operation Parameter Plots window, Safety uplift tab

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Figure 6.29: Operation Parameter Plots window, Safety hydraulic heave tab

6.5

Stresses in Geometry
In the Results menu, choose the Stresses in Geometry option to display the vertical stress
per vertical drawn in the geometry. The blue part represents the water pressure and the dark
green part represents the additional effective stress. Use the Pan
and Zoom
buttons to select the part to be viewed in detail.

Figure 6.30: Stresses in Geometry window

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6.6

Subsidence Profiles
Only available if the Micro tunneling model in the Model window (section 4.1) is selected. In
the Results menu, choose the Subsidence Profiles option to display the calculation results for
the subsidence trough as apparent at surface. Subsidence is related to the volume loss due
to the tunnel excavation, e.g. the excess soil removed by the Micro Tunneling Boring Machine
(MTBM). The subsidence mechanism is described in detail in section 24.3.

Figure 6.31: Subsidence Profiles window

Vertical
Fix axis

Use the Pan

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Type the vertical number that must be displayed or click the arrow-up and
arrow-down keys
to scroll through the available verticals.
Enable this check-box to fix the range of the vertical axis of the graph of
subsidence whatever the selected time step.

and Zoom

buttons to select the part to be viewed in detail.

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7 Graphical Geometry Input
This chapter explains how to define the soil layers in a two-dimensional cross section by
drawing, using the shared D-Series options for geometry modeling.

section 7.1 introduces the basic geometrical elements that can be used.
section 7.2 lists the restrictions and assumptions that the program imposes during geometry creation.

section 7.3 gives an overview of the functionality of the View Input window.
section 7.4 describes the creation and section 7.5 describes the manipulation of general
graphical geometry using the View Input window.
Besides graphical input, the geometry can also be imported or tabular forms can be used
(see section 4.3.2). See the MGeoBase manual for a description of special features to create
cross-section geometry semi-automatically from CPT and/or boring records.
7.1

Geometrical objects
Geometry can be built step-by-step through the repetitive use of sketching, geometry creation
and geometry manipulation. Each step can be started by using line-shaped construction elements (section 7.1.2) to add line drawings. After converting these drawings to valid geometry
parts, the specific geometry elements created can be manipulated (section 7.1.1).

7.1.1

Geometry elements
Geometry can be composed from the following geometry elements:
Points

Boundary lines
Boundaries
PL-lines
Phreatic line

Layers
Materials

Limits

A point is a basic geometry element defined by its co-ordinates. As
stated earlier, the geometry is restricted to two dimensions, allowing to
define X and Z co-ordinates only.
A boundary line is a straight line piece between two points and is part
of a boundary.
A boundary is a collection of connected boundary lines that forms the
continuous boundary between layers.
A piezometric level line is a collection of connected straight line pieces
defining a continuous piezometric level.
This is a PL-line that acts as phreatic line. The phreatic line (or groundwater level) is used to mark the border between saturated and unsaturated soil.
A layer is the actual soil layer. Its geometrical shape is defined by its
boundaries, and its soil type is defined by its material.
A material defines the actual soil material (or soil type). It contains the
parameters belonging to the soil type, such as its unsaturated weight
and its saturated weight. A material can be connected to a layer in
order to define the soil type of the layer.
A limit is a vertical boundary defining the ‘end’ at either the left or right
side of the geometry. It is defined by an X co-ordinate only. Note that
this is the only type of element that cannot be deleted.

Adding, moving and deleting the above-mentioned elements are subject to the conditions for
a valid geometry (see section 7.2). For example, while dragging selected geometry elements,
the program can perform constant checks on the geometry validity (section 7.4.4). Invalid
parts will be shown as construction elements (thick blue lines).

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7.1.2

Construction elements
Besides the D-Series geometry elements (section 7.1.1), special construction elements can
also be used for sketching the geometry graphically. These elements are not a direct part of
the geometry and the restrictions on editing (adding, moving, and deleting); these elements
are therefore far less rigid. The only restriction that remains is that these elements cannot be
moved and/or defined beyond the limits of the geometry.
Lines
Poly-lines

A line Construction consists of a starting point and end point, both defined by a left-hand mouse click in the graphic input screen.
A poly-line Construction consists of a series of connected lines, all defined by a left-hand mouse click in the graphic input screen.

Construction elements will be displayed as solid blue lines. Valid constructions elements
are converted to geometry elements as soon as the geometry is (re-) generated. For more
information on adding lines and poly-lines, see section 7.4.
7.2

Assumptions and restrictions
During geometrical modeling, the program uses the following assumptions.

Boundary number 0 is reserved for the base.
A soil layer number is equal to the boundary number at the top of the layer.
The boundary with the highest number defines the soil top surface.
A material (soil type) must be defined for each layer – except for layer 0 (base). Different
layers can use the same material.
All the boundaries must start and end at the same horizontal co-ordinates.
Boundaries should not intersect, but they may coincide over a certain length.
All horizontal co-ordinates on a boundary must be ascending – that is, the equation
X[i + 1] ≥ X[i] must be valid for each following pair of X co-ordinates (vertical parts
are allowed).
PL-lines may intersect and may coincide with each other over a certain length.
PL lines and layer boundaries may intersect.
All PL-lines must start and end at the same horizontal co-ordinate.
All X co-ordinates on a PL-line must be strictly ascending – that is, the equation
X[i + 1] > X[i] must be valid for each following pair of X co-ordinates (no vertical parts allowed).

One way for inputting geometry data is through the Geometry menu, as explained in the
Reference section (section 4.3). This section describes an other way to create and manipulate
geometry graphically using the tool buttons of the View Input window.
7.3

View Input Window

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7.3.1

General
To use the View Input option, click the Geometry tab to activate it in the regular View Input
window or use the menu to select it.

Figure 7.1: View Input window, Geometry tab

When the Geometry tab in the View Input window is selected, it displays a graphical representation of only the geometrical data. On the left of the window, the Edit and Tools buttons
are displayed (section 7.3.2). On the right, the legend belonging to the geometry is displayed
(section 7.3.3). At the bottom of the window, the title panel and the info bar are displayed.
The title panel displays the project titles defined using the Properties option in the Project
menu. The info bar provides information (from left to right) about the current cursor position,
the current mode and the object currently selected. The legend, title panel and info bar are
optional and can be controlled using the Properties option in the Project menu.
It is possible to use three different modes when working in the Geometry tab of the View Input
window:
Select
Add

Zoom

The Select mode is the default mode and enables the user to select existing
elements in the window.
The Add mode allows the addition of elements using one of the Add buttons.
By selecting one of these buttons, one switches to the Add mode. As long as
this mode is active, the user can add the type of element which is selected.
The Zoom mode allows the user to view the input geometry in different sizes.
By selecting one of the Zoom buttons or the Pan button, one activates the
Zoom mode. While in this mode, the user can repeat the zoom or pan actions
without re-selecting the buttons.

It is possible to change modes in the following ways. When in Add or Zoom mode, it is
possible to return to the Select mode by clicking the right-hand mouse button, or by pressing
the Escape key, or by clicking the Select mode button. To activate the Add mode, select one
of the Add buttons. To activate the Zoom mode, select one of the Zoom buttons or the Pan
button.
Note: The current mode is displayed on the info bar at the bottom of the View Input window.

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7.3.2

Buttons
Edit panel:
Select and Edit mode
In this mode, the left-hand mouse button can be used to graphically select a previously defined grid, load, geotextile or forbidden line. Items can then be deleted
or modified by dragging or resizing, or by clicking the right-hand mouse button and
choosing an option from the menu displayed. Pressing the Escape key will return
the user to this Select and Edit mode.
Pan
Click this button to change the visible part of the drawing by clicking and dragging
the mouse.
Add point(s) to boundary / PL-line
Click this button to add points to all types of lines (lines, poly-lines, boundary lines,
PL-lines). By adding a point to a line, the existing line is split into two new lines. This
provides more freedom when modifying the geometry.
Add single lines(s)
Click this button to add single lines. When this button is selected, the first left-hand
mouse click will add the info bar of the new line and a “rubber band” is displayed
when the mouse is moved. The second left-hand mouse click defines the end point
(and thus the final position) of the line. It is now possible to either go on clicking start
and end points to define lines, or stop adding lines by selecting one of the other tool
buttons, or by clicking the right-hand mouse button, or by pressing the Escape key.
Add polyline(s)
Click this button to add poly-lines. When this button is selected, the first left-hand
mouse click adds the starting point of the new line and a “rubber band” is displayed
when the mouse is moved. A second left-hand mouse click defines the end point
(and thus the final position) of the first line in the poly-line and activates the “rubber
band” for the second line in the poly-line. Every subsequent left-hand mouse click
again defines a new end point of the next line in the poly-line. It is possible to end
a poly-line by selecting one of the other tool buttons, or by clicking the right-hand
mouse button, or by pressing the Escape key. This also stops adding poly-lines altogether.
A different way to end a poly-line is to double-click the left-hand mouse button. Then
the poly-line is extended automatically with an ‘end line’. This end line runs horizontally from the position of the double-click to the limit of the geometry in the direction
the last line of the poly-line was added. Therefore, if the last line added was defined
left to right, the ‘end line’ will stop at the right limit. Note that by finishing adding a
poly-line this way, it is possible to start adding the next poly-line straight away.

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Add PL-line(s)
Click this button to add a piezometric level line (PL-line). Each PL-line must start
at the left limit and end at the right limit. Furthermore, each consecutive point must
have a strictly increasing X co-ordinate. Therefore, a PL-line must be defined from
left to right, starting at the left limit and ending at the right limit. To enforce this, the
program will always relocate the first point clicked (left-hand mouse button) to the left
limit by moving it horizontally to this limit. If trying to define a point to the left of the
previous point, the rubber band icon indicates that this is not possible. Subsequently
clicking on the left side of the previous point, the new point will be added at the end
of the rubber band icon instead of the position clicked.
As with poly-lines, it is also possible to end a PL-line by double-clicking the left-hand
mouse button. In this case, the automatically added ‘end line’ will always end at the
right limit.
To stop adding PL-lines, select one of the other tool buttons, or click the right-hand
mouse button, or press the Escape key.
Zoom in
Click this button to enlarge the drawing, then click the part of the drawing which is to
be at the center of the new image. Repeat if necessary.
Zoom out
Click this button, then click on the drawing to reduce the drawing size. Repeat if
necessary.
Zoom rectangle
Click this button then click and drag a rectangle over the area to be enlarged. The
selected area will be enlarged to fit the window. Repeat if necessary.
Measure the distance between two points
Click this button, then click the first point on the View Input window and place the
cross on the second point. The distance between the two points can be read at the
bottom of the View Input window. To turn this option off, click the escape key.
Add calculation vertical
Click this button to graphically define the position of a vertical.

Tools panel:
Undo zoom
Click this button to undo the zoom. If necessary, click several times to retrace each
consecutive zoom-in step that was made.
Zoom limits
Click this button to display the complete drawing.
Same scale for X and Y axis
Click this button to use the same scale for the horizontal and vertical directions.
Automatic regeneration of geometry on/off
When selected, the program will automatically try to generate a new valid geometry
whenever geometry modifications require this. During generation, (poly)lines (solid
blue) are converted to boundaries (solid black), with interjacent layers. New layers
receive a default material type. Existing layers keep the materials that were assigned
to them. Invalid geometry parts are converted to construction elements.
Automatic regeneration may slow down progress during input of complex geometry,
because validity will be checked continuously.
Undo
Click this button to undo the last change(s) made to the geometry.

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Redo
Click this button to redo the previous Undo action.
Delete
Click this button to delete a selected element. Note that this button is only available
when an element is selected. See section 7.5.2 for more information on how using
this button.
7.3.3

Legend
At the right side of the View Input window (Figure 7.2) the legend belonging to the geometry
is shown. This legend is present only if the Legend check-box in the View Input tab of the
Project Properties window is activated (see section 4.1.2).

Figure 7.2: View Input window, Geometry tab (legend displayed as Layer Numbers)

In the Geometry tab of the View Input window, it is possible to change the type of legend.
When a soil type box in the legend is right clicked, the menu from Figure 7.3 is displayed.

Figure 7.3: Legend, Context menu

With this menu, there are three ways to display the legend of the layers:

As Layer Numbers: the legend displays one box for each layer. Each layer (and therefore each box) is displayed in a different standard color. Next to each box, the layer
number and the material name are displayed, corresponding to the color and number
of the layer in the adjacent Geometry window (see Figure 7.2).
As Material Numbers: the legend displays one box for each material. Each material
(and therefore each box) is displayed in a different color which can be changed by
the user (see below). Next to each box, the material number and name are displayed,
corresponding to the color and number of the material in the adjacent Geometry window
(see Figure 7.4).

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As Material Names: the legend displays one box for each material. Each material (and
therefore each box) is displayed in a different color which can be changed by the user
(see below). Next to each box, only the material name is displayed, corresponding to
the color and name of the material in the adjacent Geometry window (see Figure 7.5).

Figure 7.4: View Input window, Geometry tab (legend displayed as Material Numbers)

Figure 7.5: View Input window, Geometry tab (legend displayed as Material Names)

Unlike the standard colors used to display layers with their layer colors, it is possible to define
different colors used when displaying materials. To change the color assigned to a material,
right click the material box. The menu from Figure 7.6 is displayed.

Figure 7.6: Legend, Context menu (for legend displayed as Materials)

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When selecting Material Colors the Color window appears (Figure 7.7), in which the user can
pick a color or even define customized colors himself (by clicking the Define Custom Colors
button).

Figure 7.7: Color window

7.4
7.4.1

Geometry modeling
Create a new geometry
There are two ways to create a new geometry without the wizard:

Open the Geometry menu and choose New.
Open the File menu and choose New. In the New File window displayed, select New
Geometry and click OK (see section 4.3.2).
In both cases, the Geometry tab of the View Input window is displayed (Figure 7.8) with the
default limits of the geometry (from 0 to 100 m).

Figure 7.8: View Input window, Geometry tab

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7.4.2

Set limits
The first thing to do when creating new geometry is to set the model limits. This is possible by
selecting and then dragging the limits to their proper place one by one. It is also possible to
select a limit and edit its value by clicking the right-hand mouse button after selecting the limit
and then choosing the Properties option in the pop-up menu. The property window belonging
to the selected limit is displayed (Figure 7.9), enabling to define the new X co-ordinate for this
limit.

Figure 7.9: Right Limit window

7.4.3

Draw layout
It is possible to use the Add single line(s), Add polyline(s) and Add point(s) to boundary / PLline buttons to draw the layout of the geometry. See section 7.3.2 for more information’s on
how using those buttons.
Add single line(s)

and Add polyline(s)

Each (poly)line is displayed as a solid blue line, and each point as a small black rectangle
(Figure 7.10).

Figure 7.10: Representation of a polyline

The position of the different points of a (poly)line can be modified by dragging the points as
explained in section 7.5.4 or by editing the (poly)line. This is done by clicking the right-hand
mouse button after selecting the (poly)line and then choosing the Properties option in the
pop-up menu.
The underlying grid helps the user to add and edit (poly)lines. Use the Properties option in
the Project menu to adjust the grid distance and force the use of the grid by activating Snap to
grid. When this option is activated, each point is automatically positioned at the nearest grid
point.
The specified line pieces must form a continuous line along the full horizontal width of the
model. This does not mean that each line piece has to be connected exactly to its predecessor
and/or its successor. Intersecting line pieces are also allowed, as shown in the examples of
Figure 7.11.

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(1)

(2)

(3)

Figure 7.11: Examples of configurations of (poly)lines

Configuration (1) is allowed. The different lines are connected and run from boundary
to boundary

Configuration (2) is also allowed. The different are connected. They are defined as
being connected because they intersect. The line construction runs from boundary to
boundary.

Configuration (3) is illegal, as there is no connection with the left boundary.
Add point(s) to boundary / PL-line
Use this button to add extra points to lines (lines, polylines, boundary lines, PL-lines). By
adding a point to a line, the existing line is split into two new lines. This provides more freedom
when modifying the geometry.
Note: When the Add point(s) to boundary/PL-line button is clicked, each left-hand mouse
click adds a new point to the nearest line until one of the other tool buttons is selected, or click
the right-hand mouse button, or press the Escape key.
7.4.4

Generate layers
to start or stop the automatic
Use the Automatic regeneration of geometry on/off button
conversion of construction elements to actual boundaries and layers. Valid (poly)lines are
converted to boundaries, which are displayed as black lines. Invalid lines remain blue.
Layers are generated between valid boundaries, and default soil types are assigned.
It is possible to modify the soil type assigned to a layer by first selecting the layer and then
clicking the right-hand mouse button and choosing the Layer Properties option in the popup menu to display the Layer window (see Figure 7.19 in section 7.5.3). Once a material
has been assigned to a layer, this material will continue to be associated to that layer in
subsequent conversions of construction elements as long as the layer is not affected by those
conversions.
The most common cause of invalid (poly)lines is that they are not part of a continuous polyline running from limit to limit. Sometimes, lines appear to start/end at a limit without actually
being on a limit. Figure 7.12 gives an example: on the left geometry (1), the end of the line
seems to coincide with the boundary. However, zooming in on the point (geometry (2) on the
right) reveals that it is not connected to the boundary. Therefore the geometry is considered
invalid.

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(1)

(2)

Figure 7.12: Example of invalid point not connected to the left limit

It is possible to correct this by dragging the point to the limit while the specific area is zoomed
in or by selecting the point, clicking the right-hand mouse button, choosing the Properties
option in the pop-up menu (section 7.5.3) and making the X co-ordinate of the point equal to
the X co-ordinate of the limit.
7.4.5

Add piezometric level lines
It is possible to use the Add PL-line(s) to add PL-lines
button. When adding a PL-line,
D-G EO P IPELINE imposes the limitation that the subsequent points of the PL-line have an increasing X co-ordinate. Furthermore the first point of a PL-line is to be set on the left boundary
and the last point on the right boundary.
It is possible to change the position of the different points of a PL-line by dragging the points
as explained in section 7.5.4 or by editing the PL-line. This is done by selecting the PL-line,
clicking the right-hand mouse button and choosing the Properties option in the pop-up menu
(section 7.5.3).

7.5
7.5.1

Graphical manipulation
Selection of elements
After selecting a geometry element it is possible to manipulate it. In order to be able select a
geometry element, the select mode should be active. Then it is possible to select an element
by clicking the left-hand mouse button. To select a layer, click on the layer number, material
number or material name, depending on the option chosen in the Properties dialog in the
Project menu. When successfully selected, the element will be displayed highlighted (for
example, a point will be displayed as a large red box instead of a small black box).
The following remarks are relevant to selection accuracy and ambiguity.
Ambiguous selection
A selection of geometrical elements can be ambiguous. Figure 7.13 gives an example: a user
may want to select a point, a boundary line, a boundary or a PL-line. As several elements are
in close proximity to each other, D-G EO P IPELINE does not automatically select an element.

Figure 7.13: Selection accuracy as area around cursor

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In this case D-G EO P IPELINE requires the user to assign the element that is to be selected by
displaying a pop-up menu (Figure 7.14) with the available types of elements within the range
of the selection click. It is possible to select the element from this menu.

Figure 7.14: Selection accuracy as area around cursor

Clear selection
It is possible to clear a selection by clicking in an area without geometry elements in the direct
area.
7.5.2

Deletion of elements
Click the Delete button
element is selected.

to delete a selected element. This button is only available when an

When a point is selected and deleted, it and all lines connected to it are deleted as shown in
Figure 7.15.

After

Before

Figure 7.15: Example of deletion of a point

When a geometry point (a point used in a boundary or PL-line) is selected and deleted, the
program deletes the point and its connected boundary lines as shown in Figure 7.16. It then
inserts a new boundary that reconnects the remaining boundary lines to a new boundary.

Before

After

Figure 7.16: Example of deletion of a geometry point

Deletion of a geometry element (boundary, boundary line, geometry point, PL-line) can result
in automatic regeneration of a new valid geometry, if the Automatic regeneration option is
switched on.
When a line is selected and then deleted, the line and its connecting points are deleted as
shown in Figure 7.17. In addition the layer just beneath that boundary is deleted. All other line
parts that are not part of other boundaries will be converted to construction lines.

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Before

After
Figure 7.17: Example of deletion of a line

7.5.3

Using the right-hand mouse button
When using the mouse to make geometrical manipulations, the right mouse button enables
full functionality in a pop-up menu, while the left button implies the default choice. The options
available in the pop-up menu depend on the selected geometrical element and the active
mode.
When the Select mode is active and the right-hand mouse button is clicked, the pop-up menu
of Figure 7.18 is displayed.

Figure 7.18: Pop-up menu for right-hand mouse menu (Select mode)

Properties...

Delete
Undo
Redo
View
Preferences...
Statistics

Layer
Properties...

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When this option is clicked, the property editor for the selected object
is displayed. This procedure is performed by first selecting an object by
clicking on it with the left-hand mouse button. Then clicking the righthand mouse button anywhere in the graphic window will display the
pop-up menu. It is possible to use the property editor to quickly adapt
the values (properties) of the selected object. Each type of element
requires its own properties and therefore its own property editor as
shown from Figure 7.20 to Figure 7.23 below.
This option deletes the element that has been selected (see the comments for the Delete button in section 7.5.2).
This option will undo the last change(s) made to the geometry.
This option will redo the previous Undo action.
This option opens the Properties dialog in the Project menu as displayed in.
It is possible to use this option to view a window displaying all the vital
statistics of the input data. Note that in the window construction lines
are called free lines.
This option is a special feature that edits the material properties of layers. It is possible to click anywhere in a layer and directly choose this
option to edit its properties (Figure 7.19). Clicking outside the geometry
layers will display the menu with the Layer Properties option disabled,
as there is no layer for which properties can be displayed.

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Delete All Loose
Lines

Delete All Loose
Points

This option will delete all loose lines. Loose lines are actually construction lines that are not part of the boundaries or PL-lines (therefore, all
lines displayed as solid blue lines). With this option, it is possible to
quickly erase all the “leftover bits” of loose lines that may remain after
converting lines to a geometry.
This option will delete all loose points.

Figure 7.19: Layer window (Property editor of a layer)

Figure 7.20: Point window (Property editor of a point)

Figure 7.21: Boundary window (Property editor of a polyline)

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Figure 7.22: Boundary window (Property editor of a line)

Figure 7.23: PL-line window (Property editor of a PL-line)

Note: In the Boundary and PL-line properties windows, only the point’s number can be
modified, not the X and Z co-ordinates.
7.5.4

Dragging elements
One way to modify elements is to drag them to other locations. To drag an element, first select
it. Once the element has been selected, it is possible to drag it by pressing and holding down
the left-hand mouse button while relocating the mouse cursor. Dragging of geometry elements
can result in automatic regeneration of geometry, if this option is switched on (section 7.4.4)
as shown in the example of Figure 7.24: when the selected point is moved upwards, a new
geometry will be created. D-G EO P IPELINE creates new layers according to this new geometry.

Before

After
Figure 7.24: Example of dragging of a point

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8 Tutorial 1: Calculation and assessment of the drilling fluid
pressure
This first exercise considers installation of a steel pipeline by using the horizontal directional
drilling technique. The exercise focuses on the calculation of the minimal required drilling
fluid pressure which is necessary to perform a horizontal directional drilling and the maximum
allowable drilling fluid pressure, which depends on the strength and deformability of the soil
through which the drilling is carried out.
The objectives of this tutorial are:

To learn how to start up a calculation in D-G EO P IPELINE;
To calculate the minimum required drilling fluid pressure;
To calculate the maximum allowable drilling fluid pressure;
Assessment of the calculated drilling fluid pressures.

The following module is needed:

D-G EO P IPELINE Standard module (HDD)
This tutorial is presented in the file Tutorial-1.dri.
Introduction to the case

0m
40
R=

exit: X= 190m

The horizontal directional drilling technique is used to install a steel pipeline in a silty sand
layer. The pipeline configuration is shown in Figure 8.1. The soil properties are provided in
Table 8.1.
entry: X= -90m

8.1

+5m

15º

pipeline
-15m

silty sand

Figure 8.1: Pipeline configuration for Tutorial 1

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Table 8.1: Properties of the silty sand layer (Tutorial 1)

Dry unit weight
Wet unit weight
Cohesion
Angle of internal friction
Undrained strength top
Undrained strength bottom
E modulus top
E modulus bottom
Poisson’s ratio

[kN/m3 ]
[kN/m3 ]
[kN/m2 ]
[◦ ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[-]

18
20
0
30
0
0
10000
15000
0.35

The pipeline material used in this tutorial is a steel 240 and its properties are given in Table 8.2.
Table 8.2: Properties of steel material (Tutorial 1)

Material quality
Negative wall thickness tolerance
Yield strength
Partial material factor
Partial material factor test pressure
Young’s modulus
Outer diameter
Wall thickness
Unit weight pipe material
Design pressure
Test pressure
Temperature variation

8.2
8.2.1

[%]
[N/mm2 ]
[-]
[-]
[N/mm2 ]
[mm]
[mm]
[kN/m3 ]
[Bar]
[Bar]
[◦ C]

Steel 240
0
240
1.1
1
205800
323.9
7
78.50
8
9
5

Project
Start
To create a new project, follow the steps described below:
1. Start D-G EO P IPELINE from the Windows task-bar (Start/Programs/Deltares Systems/ D-G EO P IPELINE).
2. Click File and choose New on the menu bar to start a new project.
3. In the New File window, select the option New geometry to start (Figure 8.2).

Figure 8.2: New File window

This will result in the empty geometry window shown in Figure 8.3.

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Figure 8.3: View Input window

4. Save the project by clicking Save As in the File menu and by entering as
project name.
5. Click Save to close this window.
8.2.2

Project Properties
To give the project a meaningful description, follow the steps described below:
6. On the menu bar, click Project and then choose Properties to open the Project Properties
window (Figure 8.4).

Figure 8.4: Project Properties window, Identification tab

7. Fill in and for
Title 1 and Title 2 respectively in the Identification tab.

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In the other tab of the Project Properties window, some defaults values are modified in order
to make the graphical geometry more understandable.
8. Select the View Input tab (Figure 8.5) to change the settings of the View Input window.

Figure 8.5: Project Properties window, View input tab

9. Mark the Points check-box of the Labels sub-window in order to display the point’s number.
10. Mark the Snap to grid check-box in order to ensure that objects align to the grid automatically when they are moved or positioned.
11. Before closing the Project Properties window, mark the Save as default check-box to use
the settings previously inputted every time D-G EO P IPELINE is started, which means for the
other tutorials.
12. Click OK to confirm.
8.2.3

Model
The horizontal directional drilling technique is used in this first tutorial.
13. Select Model from the Project menu bar to open the Model window (Figure 8.6).
14. Check that the Horizontal directional drilling model is selected (default model).
15. Click OK to confirm.

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Figure 8.6: Model window

8.3

Geometry
Firstly, the geometry of Figure 8.1 needs to be put in D-G EO P IPELINE. In order to do this, the
following actions should bee performed:
16. First enlarge the dimensions of the geometry window by selecting the left boundary by
clicking the left mouse button, then click the right button and select Properties. This will result in the coordinate window for the left boundary as shown in Figure 8.7. Enter coordinate
X of <-100 m>.

Figure 8.7: Left Limit window

17. Repeat the previous described actions for the right boundary and shift the boundary to
coordinate X of <200 m>. The width in between the left and the right boundary is now
300 m.
from the Tools section so that the drawn geom18. Choose the drawing option Zoom limits
etry appears in the center of the screen.
19. Choose the drawing option from the edit-window Add single line
to draw the surface
line of the longitudinal cross section of the horizontal directional drilling and position the
straight surface line at Z = 5 m. Use the right mouse button to finish the line.
20. Choose the drawing option Add single line to draw the lower boundary of the longitudinal
cross section of the horizontal directional drilling and position the straight lower boundary
line at Z = –40 m.
21. Choose the drawing option from the Tools section Automatic regeneration of geometry so
that the geometry as shown in Figure 8.8 appears. If the Automatic regeneration option
already is selected, click on the Edit icon to regenerate the geometry.
and position the level of
22. Choose the drawing option from the edit-window Add pl-line(s)
the groundwater at coordinate Z = 0 m. The blue dashed line represents the groundwater
line (PL line).

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Figure 8.8: View Input window, Geometry tab

8.3.1

Soil layer properties
The properties of the soil layers should be specified in the menu materials which can be
entered by clicking soil. In this tutorial only one soil layer is considered.
23. Click Soil and select Materials on the menu bar to open the Materials window (Figure 8.9)
and enter the soil data.
24. Add a new material by choosing Add button below the materials list on the left side of the
window with the new .
25. Enter the soil data as given in Table 8.1.
26. Finish the input of soil data by clicking OK.

Figure 8.9: Materials window

The defined soil properties and the groundwater level have to be assigned to the drawn geometry of the longitudinal cross section. The assignments can be carried out by clicking
geometry and choosing the subsequent described options on the menu bar.

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8.3.2

Phreatic Line
27. On the Geometry menu, select Phreatic Line to open Phreatic Line window (Figure 8.10)
in which the phreatic line for calculation of the groundwater pressures can be selected.
28. Choose PL–line nr. <1> (only one phreatic line is available) and click OK.

Figure 8.10: Phreatic Line window

8.3.3

Layers
29. Click Geometry and select Layers on the menu bar to assign the soil properties to the soil
layers in the longitudinal cross section. To assign a material to a layer, select the Material
tab.
30. Assign the properties of the defined layer Silty Sand to layer number one in the longitudinal
cross section. The available soil layers with defined properties are shown in left column
of the materials window. The layers in the longitudinal cross section are shown in the
right column of the materials window. The defined properties are assigned to layer nr 1
by clicking the arrow in between the columns. This will result in the Material tab shown in
Figure 8.11.

Figure 8.11: Layers window, Materials tab

31. Click OK to quit the window and return to the geometry window to watch the change of
layer name in the legend.
8.3.4

PL-Lines per Layers
32. Click Geometry and select PL–lines per Layers on the menu bar to open the PL–lines
per Layer window (Figure 8.12) in which the defined PL–lines to the soil layers in the
longitudinal cross section can be defined. This window contains the information for the

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calculation of the groundwater pressure distribution. In this tutorial only one PL–line is
defined. The groundwater pressure at the top of the silty sand layer and the bottom of this
layer should be calculated based on the hydraulic head of PL–line 1.
33. Click OK to close the window.

Figure 8.12: PL-lines per Layers window

8.3.5

Check Geometry
34. The geometry can be tested by clicking Geometry and selecting Check Geometry on the
D-G EO P IPELINE menu bar. If the geometry is entered properly, the message shown in
Figure 8.13 appears.
35. Click OK to close the window.

Figure 8.13: Check Geometry window

8.4

Pipeline Configuration
36. Click Pipe and select Pipeline Configuration on the menu bar to open the Pipeline configuration window in which the pipeline configuration can be put in.
37. Enter the values given in Figure 8.1 of the introduction.
38. Select a Pulling direction product pipe as indicated in Figure 8.14.

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Figure 8.14: Pipeline Configuration window

39. Confirm by clicking OK.
40. Watch the entered pipeline configuration on the Input tab of the View Input window (Figure 8.15).

Figure 8.15: View Input window, Input tab

8.5

Soil behavior
When the borehole is created, the drilling fluid will exert pressure on the borehole wall and the
soil next to the borehole. When the pressure rises above a certain value, plastic deformation
of the soil will occur, initially adjacent to the borehole. When the pressure is increased further
beyond this value, the zone with plastic deformation will increase. If the zone with plastic
deformation reaches the surface a blow-out will occur. Besides the growth of the plastic zone
due to high drilling fluid pressures, formation of cracks in the borehole wall in granular soils will
take place before the plastic zone reaches its maximum expansion. The formation of cracks
around the borehole in granular soils is dependent on the strain of the bore hole wall which
occurs when the drilling fluid pressure is increasing and the borehole is expanding.
Crack formation and growth of the plastic zone are dependent upon soil characteristics. Soil
layers with a very high strength and/or a very high stiffness are suitable for drilling with high

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drilling fluid pressures.
Strength of soil layers is dependent on the drained or undrained behavior of soil layers during
application the drilling fluid pressure on the bore hole wall. Depending on the permeability
of the soil layer, the soil will behave drained or undrained. The coarser granular soils are
usually well permeable so that the excess water pressure due to the drilling fluid pressures
will dissipate easily. The strength of the soil which exhibits this drained behavior can be
calculated using the drained (effective) strength parameters effective cohesion (c) and angle
of internal friction (ϕ). In case of undrained behavior, which usually occurs in very fine grained
cohesive soils, the strength of the soil should be calculated using the undrained cohesion (cu ).
41. Click GeoObjects and select Boundaries Selection on the menu bar to select the input window specification of the soil behavior. This will result in the Boundaries Selection window
shown in Figure 8.16.
42. Choose the boundary between the undrained and drained layer on top of layer nr 1. This
choice results in drained behavior of layer nr 1. The other in the boundaries window mentioned boundary in between compressible and incompressible layers can be chosen on top
of layer nr 1 (see tutorial 3 for explanation about this compressibility boundary).

Figure 8.16: Boundaries Selection window

8.6

Calculation Verticals
The locations in the longitudinal cross section at which a calculation should be carried out
must be specified by the user. The user is able to perform calculations at uniform distances
along the longitudinal cross section but is also able to perform more calculations at short
distances at areas of interest.
43. Click GeoObjects and select Calculation Verticals on the menu bar to select the Calculation
Verticals window for specification of the calculation locations along the longitudinal cross
section.
44. Choose the Automatic generation of L co-ordinates option on the right side of the window
and choose the following values: <–80 m> for First, <180 m> for Last and <20 m> for
Interval.
45. Click on the Generate button and watch the result of automatic vertical generation on
the left side of the Calculation Verticals window. This will result in the window shown in
Figure 8.17.
46. Click OK to confirm the selected verticals and switch to the input window to watch the
location of the verticals in the longitudinal cross section.

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Figure 8.17: Calculation Verticals window

8.7

Product Pipe Material Data
The dimensions and the properties of the product pipe which should be installed in the reamed
borehole should be specified. Especially the outer diameter is important for the calculation of
the drilling fluid pressures during the pull back operation.
47. Click Pipe and select Product Pipe Material Data on the menu bar to open the Product Pipe
Material Data window for specification of the dimensions and properties of the product pipe.
48. Click on the button Add on the left side of the window to declare a pipeline with the name
.
49. Enter the values given in Table 8.2 for Pipe 1 in the fields on the right side of the window
as shown in Figure 8.18.
50. Click OK to confirm.

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Figure 8.18: Product Pipe Material Data window

8.8

Drilling Fluid Data
Various types of drilling fluids exist; the drilling fluid has properties to transport the cuttings
from the borehole to the surface. The flow behavior, which depends on the drilling fluid properties, is an important characteristic for the development of drilling fluid pressure during the
different drilling stages.
Generally, the flow behavior of drilling fluid can be described with the Bingham model. The
Bingham model is used in D-G EO P IPELINE and describes the fluid by means of a viscosity
term and a threshold term from which flow is initialized. The threshold is called the yield point.
D-G EO P IPELINE calculates the required minimum fluid pressure at the calculation verticals.
During all stages of the drilling process, a pipe is present in the borehole, drill pipe or product
pipe. The return flow of drilling fluid with cuttings occurs in the annulus between the borehole
wall and the pipe. The required fluid pressure to initiate flow depends on the width of the
annulus (radius borehole minus radius drill pipe), the properties of the drilling fluid and the
required annular fluid flow rate.
The properties of the drilling fluid and the operation parameter values should be specified in
D-G EO P IPELINE.
51. Click Pipe on the menu bar and select Drilling Fluid Data to open the Drilling Fluid Data
window for specification of properties of the drilling fluid and the operation parameter values.
52. Enter the values given in Figure 8.19.
53. Click OK to confirm the input.

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Figure 8.19: Drilling Fluid Data window

8.9

Factors
D-G EO P IPELINE performs the calculations of the maximum allowable drilling fluid pressures
according the Dutch regulations described in the NEN 3650 and 3651. The safety philosophy
described in the NEN 3650-1 Annex B and D (NEN, 2012a) is applied on the calculations.
54. Click Defaults on the menu bar and select Factors to open the Factors window in which
the default values of the contingency and safety factors are shown and can be modified.
Since the window shown in Figure 8.20 shows all factors according to the Dutch regulations
adapting the values is not necessary.
55. Click OK to confirm.

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Figure 8.20: Factors window

8.10

Results
The calculation of the drilling fluid pressures during the three stages of installation of the steel
pipe using the horizontal directional drilling technique can be started from the D-G EO P IPELINE
menu.
56. Click Calculation and select Start on the menu bar to start the calculation or press the
function key F9. D-G EO P IPELINE automatically saves the file during the calculation.
57. Click Results and select Drilling fluid pressure plots on the menu bar to watch the results of
the drilling fluid pressure calculations for the pilot drilling. The window shown in Figure 8.21
will appear. The graph shows the maximum allowable pressures (upper limit related to soil
cover and lower limit related to deformation of the borehole) and the minimal required
drilling fluid pressure for transportation of the cuttings.

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Figure 8.21: Drilling Fluid Pressures window

58. Click on the tabs Prereaming and Reaming and pullback to watch the results of the other
drilling stages.
59. Close the window to return to the main window.
Notice that the minimal required drilling fluid pressure is lower than the maximal allowable
drilling fluid pressure in the pilot drilling stage. The risk on a blow out is therefore very small.
Of course, due to the decreasing soil cover, the last meters of the pilot drilling the minimal
required drilling fluid pressure is higher than the allowable drilling fluid pressure, but in this
situation the distance where the minimal required drilling fluid is higher than the maximum
allowable pressure is very small.
8.11

Conclusion
Various input windows are used to enter the details of a project that is to be modeled and
analyzed. Once these details have been put in, they can be used to calculate a range of
results, including drilling fluid pressures during the three stages of the HDD technique. One
way to view these results is to display them graphically on the screen.

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9 Tutorial 2: Stress analysis of steel pipes and polyethylene pipes
This second exercise considers installation of a steel pipeline and installation of a polyethylene pipeline by using the technique horizontal directional drilling. The exercise focuses on
the stress analysis for the different installation stages, which is required to assess whether
installation of the pipeline according the design is executable or not.
The objectives of this tutorial are:

To calculate the pulling force on the pipeline during the pull back operation.
To calculate the stresses in the pipeline during the different installation stages.
Assessment of the calculated stresses in the pipeline.
To perform a Special Stress Analysis.
To perform a calculation for a polyethylene pipe.

The following module is needed:

D-G EO P IPELINE Standard module (HDD)
This tutorial is presented in the files Tutorial-2a.dri, Tutorial-2b.dri and Tutorial-2c.dri.
Introduction to the case

0m
40
R=

exit: X= 190m

The pipeline configuration and the soil type is the same as those modeled in the first tutorial
(Figure 9.1).
entry: X= -90m

9.1

+5m

15º

pipeline
-15m

silty sand

Figure 9.1: Pipeline configuration for Tutorial 2

Different calculations will be performed using two pipe materials:

A steel pipe with the properties given in Table 9.1 (Tutorial 2a),
The same pipe as Tutorial 2a, but performing a Special Stress Analysis (Tutorial 2b).
A polyethylene pipe with the properties given in Table 9.1 (Tutorial 2c).

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Table 9.1: Pipe properties (Tutorial 2)

Pipe material
Material quality
Negative wall thickness tolerance
Young’s modulus
Young’s modulus (long term)
Allowable/Yield strength
Allowable strength (long term)
Partial material factor
Partial material factor test pressure
Tensile factor
Outer Diameter
Wall thickness
Unit weight pipe material
Design pressure
Test pressure
Temperature variation

[%]
[N/mm2 ]
[N/mm2 ]
[N/mm2 ]
[N/mm2 ]
[-]
[-]
[-]
[mm]
[mm]
[kN/m3 ]
[Bar]
[Bar]
[◦ C]

Tutorials 2a / 2b
Steel
Steel 355
0
205800
n.a.
355
n.a.
1.1
1
n.a.
323.9
8
78.5
8
9
5

Tutorial 2c
Polyethylene
PE 100
n.a.
1200
300
10
8
n.a.
n.a.
0.65
400
36.4
9.54
4
5
5

In the first tutorial, the assessment whether the proposed drilling line and borehole dimensions
according the design is executable or not was performed. The second tutorial considers the
assessment of stresses in pipeline during the different installation stages and after installation.
In D-G EO P IPELINE it is assumed that the pipeline remains fixed at the specified location and
that settlement of the soil layers below the pipeline does not influence the pipeline. Therefore
a relative simple pipe stress analysis can be performed.
The first installation stage at which the stresses in the pipeline are considered is the start
of the pull back operation. The pipeline with the connected pullback equipment is situated
on the rollers. Often the pipeline is not filled with water on the rollers in order to reduce the
required pulling force to pull the pipeline over the rollers. Of course when the pipeline enters
the borehole filling of a part of the pipeline (percentage of the cross section area) is sometimes
useful.
In this stage a pulling force is exerted on the pipe, which results in axial stress in the pipeline.
Near the exit point, the rollers are often configured with a certain bending radius (the so-called
overbend), so that additional axial stresses occur due to bending. The tangential stresses for
the pipeline on the rollers are negligible.
The second stage at which the stresses in the pipeline are considered is the maximum pulling
force situation during the pull back operation. At the end of the pull back operation the pulling
force usually reaches the maximum pulling force. The pulling force is calculated according
the Dutch regulations described in NEN 3650 and is mainly based on the normal forces of
the pipeline perpendicular to the borehole wall. The normal forces are caused by the buoyant
weight of the pipeline and soil reaction forces due to the bending moment in the pipeline in
the bends of the drilling line. In the second stage both the axial stresses due to pulling and
bending are calculated and the tangential stresses due to soil reaction forces are calculated.
The third stage at which the stresses in the pipeline are considered is the long term stage after
installation. When the pipeline is installed, a situation without internal pressure and a situation
with internal pressure are considered. In this final stage the drilling fluid in the borehole is

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assumed to be consolidated, so that the contribution of soil pressure on the pipeline is taken
into account for the calculation of the tangential stress.
The stresses in the pipeline are calculated for the different installation stages. According
NEN 3650 an additional calculation is made for application of internal pressure on the pipeline.
Therefore in the stress analysis according the NEN 3650, four Load Combinations (LC) are
considered:

LC 1A: start of the pullback operation
LC 1B: end of the pullback operation
LC 2: application of internal pressure on the pipeline
LC 3: pipeline after installation, without internal pressure
LC 4: pipeline after installation, with internal pressure

The calculated stresses are assessed according NEN 3650 for the steel pipelines and according NEN 3652 for the polyethylene pipelines.
9.2

Project Properties
This tutorial is based on continuation of the file used in Tutorial 1 (chapter 8).
1. Click File and select Open on the menu bar to select the Open window for the choice of
the D-G EO P IPELINE file created at the end of tutorial 1.
2. Select Tutorial–1 and click the Open button to open de file.
3. Click File and select Save as on the menu bar to select the save file window and rename
the file into .
4. Click the Save button to save the file for Tutorial 2a.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and for Title 1 and Title 2 respectively in the Identification tab.
7. Click OK.

9.3

Product Pipe Material Data
The dimensions and the properties of the product pipe which should be installed in the reamed
borehole should be specified for a pipe stress analysis.
8. Click Pipe on the menu bar and select Product Pipe Material Data to open the Product
Pipe Material Data window for specification of the dimensions and properties of the
product pipe.
9. For Pipe 1, enter the values given in Figure 9.2.
10. Click OK to confirm the specified product pipe material data.

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Figure 9.2: Product Pipe Material Data window

9.4

Engineering Data
The first step of the pipe stress analysis is the calculation of the pulling force. The magnitude
of the pulling force plays an important role in the stress distribution in the pipe during the
pill back operation. The pulling force is calculated according the specifications described in
NEN 3650.
During the pull back operation the moving pipeline contacts the wall of the borehole and
pushes with a certain forces perpendicular to the wall of borehole. These perpendicular forces
(normal forces) determine the magnitude of the shear force in axial direction during the pull
back operation.
In order to reduce the normal forces on the borehole wall the pipeline is sometimes ballasted
during the pull back operation. In the part of the HDD without significant bends, the distribution
of the normal forces on the bore hole wall is determined by the effective weight of the pipeline.
The effective weight is defined as follows:

geff = g − guplift

(9.1)

guplift = π × re2 × γdf

(9.2)

with:

where:

re
guplift
g
γdf

is the outer radius of the pipeline, in m;
is the upward force of the pipeline, in kN/m;
is the weight of the ballasted pipeline, in kN/m;
is the unit weight of the drilling fluid, in kN/m3 .

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Using the above described equation it can be calculated that filling the product pipe for 22 %
results in a nearly weightless pipe in the bore hole. Of course it is wise not to fill the product
pipe on the rollers so that the pulling force during the first part of the pull back operation can
be reduced.
11. Click Pipe and select Engineering Data on the menu bar to open the Engineering Data
window.
12. Do not mark the Pipe filled with water on rollers check-box and enter the values given in
Figure 9.3.
13. Click on the OK button to confirm the input of the specified values.

Figure 9.3: Engineering Data window

The bedding (β ) and the load angle (α) are shown in Figure 9.4. The values are used in the
pipe stress analysis to determine the moment coefficients.

Figure 9.4: Bedding and load angles on the pipeline (according to Figure D.2 of
NEN 3650-1)

9.5

Factors
D-G EO P IPELINE performs the calculations for the pipe stress analysis according the Dutch
regulations described in the NEN 3650 and 3651. The safety philosophy described in Annex
B and D of the NEN 3650-1 (NEN, 2012a) is applied on the calculations.

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14. Click Defaults on the menu bar and select Factors to open the Factors window for watching
the default values or for alternating these values. Since the window shown in Figure 9.5
shows all factors according the Dutch regulations adapting the values is not necessary.
15. Click OK to confirm.

Figure 9.5: Factors window

9.6

Calculation and Results (Tutorial-2a)
The results of the pulling force calculation are shown in the D-G EO P IPELINE report which is
created automatically after finishing the calculations.
16. To start the calculations click Calculation and select Start on the menu bar or press the
function key F9.

9.6.1

Results of the pulling force calculation
17. Click Results and select Report on the menu bar to look at the results of the pulling force
calculation. The results can be found in paragraph 5.3 (Figure 9.6).

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Figure 9.6: Report window, Calculation pulling force (filling percentage = 22%)

18. In Figure 9.7 the characteristic locations along the drilling line at which the pulling force is
calculated are shown. Notice that the maximum pulling force is 54 kN.
entry point

exit point
ground level
T6

T5
T2

Figure 9.7: Schematic overview of the characteristic points

19. Switch back and click Pipe and select Engineering Data on the menu and alter the Part of
pipe filled with fluid during pull back to <0%>.
20. Start the calculations again by clicking Calculation and select Start on the menu bar or by
pressing the function key F9.
21. Click Results and select Report on the menu bar to watch the results of the pulling force
calculation. Notice that the pulling force has increased to 64 kN (Figure 9.8).

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Figure 9.8: Report window, Calculation pulling force (filling percentage = 0%)

9.6.2

Results of the pipe stress analysis of the steel pipe
The pipe stress analysis is described in the report. For each load combination the axial and
tangential stresses in the product pipe are calculated. The stresses are used to calculate the
maximum combined stress in the pipeline.
22. Click Results and select Report on the menu bar to watch the results of the calculated
axial and tangential stresses for each load combination/installation stage in paragraph 6.2
(see Figure 9.9).

Figure 9.9: Report window, Results Stress Analysis (Tutorial-2a)

23. Continue looking at the report and scroll down to paragraph 6.3. In the table in paragraph 6.3, the stress assessment is carried out: the calculated stresses are compared
with the yield strength of steel according to the specifications described in NEN 3650. Below the stress assessment table, the results of the deflection calculation are given (see

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Figure 9.10).

Figure 9.10: Report window, Check on calculated stresses (Tutorial-2a)

24. Notice that the calculated stresses for all load combinations are allowable. The deflection
is lower than the allowable value.
25. Look at the calculated soil load and the calculated modulus of subgrade reaction on paragraph 4.1.

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Figure 9.11: Report window, Soil Mechanical Parameters (Tutorial-2a)

9.7

Special Pipe Stress Analysis (Tutorial-2b)
The option special stress analysis can be used for a pipe stress analysis in case of additional
loads at certain location along the longitudinal cross section. Additional loads can for example
be induced by traffic or by constructions.
Assume that vertical 1 is located below a highway which will result in an additional load on
the pipeline. The load induced by soil stress is already calculated by D-G EO P IPELINE and is
assessed in the report (see section 9.6.2). The additional load at the depth of the pipeline can
be determined using load distribution theories.
26. Click File and select Save As on the menu bar to select the Save As window and rename
the file into .
27. Click the Save button to save the file for Tutorial-2b.
28. Click Defaults and select Special Stress on the menu bar to open the Special Stress Analysis window and enter the data for the special pipe stress analysis. In this window (Figure 9.12), the soil load enhanced with the traffic load should be specified. The reduced

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soil load equals <18 kN/m2 > and the modulus of subgrade reaction is independent of
the load and remains <17000 kN/m3 >. The radius is the same as defined in the pipeline
configuration <400 m>.

Figure 9.12: Special Stress Analysis window

29. Click OK to confirm.
30. Click Calculation and select Special Stress Analysis on the menu bar to start the calculation.
31. Click Results and select Report on the menu bar to look at the results on paragraph 4.3
(see Figure 9.13). Notice the difference with Figure 9.10 for Tutorial-2a.

Figure 9.13: Report window, Check on calculated stresses (Tutorial-2b)

9.8

Polyethylene Product Pipe (Tutorial-2c)
Besides a pipe stress analysis on steel pipes a pipe stress analysis on PE-pipes can be
carried out using D-G EO P IPELINE.
32. Click File and select Save As on the menu bar to select the Save As window and rename
the file into .

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33. Click the Save button to save the file for Tutorial-2c.
34. Click Pipe and select Product Pipe Material Data on the menu bar to open the Product Pipe
Material Data window for specification of the dimensions and properties of the product pipe.
35. Select Polyethylene as Pipe material for Pipe 1.
36. Enter the values given in Table 9.1.
37. Click OK to confirm.

Figure 9.14: Product Pipe Material Data window (Tutorial-2c)

38. To start the calculations, click Calculation and select Start on the menu bar or press the
function key F9.
39. Click Results and select Report on the menu bar to look at the results of the calculated
axial and tangential stresses for each load combination/installation stage in paragraph 6.2.
40. Continue looking at the report and scroll down to paragraph 6.3. In the table (Figure 9.15),
the stress assessment is carried out: the calculated stresses are compared with allowable
stresses according to the specifications described in the NEN 3650 series.

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Figure 9.15: Report window, Check on calculated stresses (Tutorial-2c)

41. Below the assessment table in paragraph 6.3, a check on short term and long term implosion is described (see paragraph 6.4 in Figure 9.16). Notice that the short term implosion
check is based on the drilling fluid pressure during the pull back operation. The long term
implosion check is based on the water pressure at the level of the pipeline.

Figure 9.16: Report window, Check for Implosion (Tutorial-2c)

9.9

Conclusion
This second tutorial analyzes the strength calculations during different stages of the HDD
technique for steel and polyethylene pipes. In both cases, the report shows that all stresses
for the different stages are allowable.

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10 Tutorial 3: Influence of soil behavior on drilling fluid pressures
and soil load on the pipe
This third exercise considers installation of a polyethylene pipeline by using the technique
horizontal directional drilling. The exercise focuses on the soil behavior and elucidates the
effect of drained and undrained soil layers on the calculation of the drilling fluid pressures and
elucidates the effect of compressible and incompressible layers on the calculation of the soil
load on the pipeline.
The objectives of this tutorial are:

To calculate the drilling fluid pressures for a layered soil sequence;
To calculate the soil load for a layered soil sequence;
Schematization of a layered soil sequence with artesian groundwater.
The following module is needed:

D-G EO P IPELINE Standard module (HDD)
This tutorial is presented in the file Tutorial-3.dri.
Introduction to the case

0m
40
R=

exit: X= 190m

This tutorial is based on continuation of the file used in Tutorial-2c (chapter 9). The steel pipe
is the same but the layered soil sequence is different as shown in Figure 10.1. The properties
of the two layers are given in Table 10.1.
entry: X= 90m

10.1

PL-line 2

+8m
+5m

15º

soft organic clay

15º

PL-line 1

0m
-5m

pipeline
-15m

silty sand

Figure 10.1: Pipeline configuration for Tutorial 3

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Table 10.1: Layer properties (Tutorial 3)

Dry unit weight
Wet unit weight
Cohesion
Angle of internal friction
Undrained strength top
Undrained strength bottom
E modulus top
E modulus bottom
Poisson’s ratio

[kN/m ]
[kN/m3 ]
[kN/m2 ]
[◦ ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[-]

Coarse sand
18
20
0
35
0
0
15000
25000
0.35

Soft organic clay
13
13
2
18
10
30
500
1000
0.45

During drilling a borehole is protected from collapsing by filling it with drilling fluid. However,
arching in the surrounding soil contributes to the stability of the borehole. As a result, arching
also reduces the total amount of soil load acting on the installed pipe.
For an ideal granular stratum, Terzaghi’s derivation has up until now been considered to be
appropriate for the situation where arching occurs and is accordingly incorporated in Dutch
pipeline standard NEN 3650 series. However, for cohesive soil layers consolidation may occur
over a period of time and this will result in a reduction of the arching effect, thereby increasing
the vertical load on the installed pipe. The latter process is added to the Dutch pipeline
standard.
For the development of arching a certain depth diameter ratio is required (Figure 10.2). At
shallow depths near the exit and entry point, the soil cover is not sufficient for turning off the
soil load above the borehole to the soil layers next to the borehole.

Figure 10.2: Arching around the borehole

During the pilot drilling the highest drilling fluid pressures occur. The risk on a blow out to the
surface or the formation of cracks around the borehole often exists. This risk is related to the
strength of the soil layers around the borehole. The strength of soil layers is dependent on
the drained or undrained behavior of soil layers during application the drilling fluid pressure
on the bore hole wall. Depending on the permeability of the soil layer, the soil will behave
drained or undrained. The coarser granular soils are usually well permeable so that the excess
water pressure due to the drilling fluid pressures will dissipate easily. The strength of the soil
which exhibits this drained behavior can be calculated using the drained (effective) strength

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parameters. In case of undrained behavior, which usually occurs in very fine grained cohesive
soils, the strength of the soil should be calculated using the undrained strength parameters.
1. Click File and select Open on the menu bar to open the Open window.
2. Select Tutorial-2c and click the Open button to open the file.
3. Click File and select Save as on the menu bar to open the Save As window and rename
the file into .
4. Click the Save button to save the file for Tutorial 3.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and for Title 1 and
Title 2 respectively in the Identification tab.
7. Click OK.
10.2

Geometry of the longitudinal cross section
This tutorial considers a layered soil sequence. The typical Dutch soil sequence of a soft
organic clay layer on top of a coarse sand layer will be considered. The organic clay layer is
compressible and exhibits a low permeability, while the sand layer is assumed incompressible
and exhibits a high permeability. The new soil layers should be specified in the geometry
window.
8. In the View Input window, switch to the Geometry tab to edit the existing soil layer sequence
icon from the Edit sub-window to draw an additional top line of
9. Click the Add single line
a soil and position the straight line at Z = -5 m.
10. Click the Automatic regeneration of geometry on/off
icon to regenerate the geometry.
11. Click the Add pl-line(s)
icon from the Edit sub-window and position the level of the
artesian groundwater at coordinate Z = 8 m. The blue dashed line, which appears in the
longitudinal cross section, represents the second groundwater line (PL line). The second
groundwater line is used to specify the water pressure distribution in the sand aquifer.

Figure 10.3: View Input window, Geometry tab

10.3

Soil layer properties
The properties of the soil layers in the layered soil sequence should now be specified.
12. Click Soil and select Materials on the menu bar to enter the soil data.

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13. Add a new material by choosing the Add button
below the materials list on the left
side of the window. Enter the soil material .
14. Enter the soil data as given in Table 10.1.
15. Add a new material by choosing the Add button
below the materials list on the left
side of the window. Enter the soil material .
16. Enter the soil data given in Table 10.1.
17. Finish the input of soil data by clicking OK.

Figure 10.4: Materials window

10.4

Finishing the geometry of the longitudinal cross section
The defined soil properties and the groundwater levels have to be assigned to the drawn geometry of the longitudinal cross section. The assignments can be carried out in the Geometry
menu.
18. Click Geometry and select Phreatic Line on the menu bar to open the Phreatic Line window
(Figure 10.5) and select PL-line <1> as phreatic line for calculation of the groundwater
pressures.
19. Click OK.

Figure 10.5: Phreatic Line window

20. Click Geometry and select Layers on the menu bar to open the Layers window. Select the
Materials tab (Figure 10.6) to assign the soil properties to the soil layers in the longitudinal
cross section.

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Figure 10.6: Layers window, Materials tab

21. Assign the properties of the defined layer Coarse Sand to layer Number 1 in the longitudinal cross section. The available soil layers with defined properties are shown in left column
of the materials window. The layers in the longitudinal cross section are shown in the right
column of the materials window. The defined properties are assigned to layer Number 1
by clicking the Assign icon
in between the left and the right columns.
22. Assign the properties of the defined layer Soft Organic Clay to layer number 2 in the longitudinal cross section. The defined properties of Soft Organic Clay are assigned to layer
Number 2 by clicking the Assign icon
in between the left and the right column.
23. Click on the OK button to quit the window and return to the Geometry tab of the View Input
window to look at the change of layers name in the legend (Figure 10.7).

Figure 10.7: View Input window, Geometry tab

24. Click Geometry and select Pl-lines per Layers on the menu bar to open the PL-lines per
Layers window to assign the defined PL–lines to the soil layers in the longitudinal cross
section. Those information’s are used for the calculation of the groundwater pressure
distribution.
25. The groundwater pressure at the top of the Soft Organic Clay layer should be calculated
based on the hydraulic head of PL–line 1, the phreatic line (Figure 10.1). Since the Coarse

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Sand layer is an aquifer with an enhanced artesian groundwater pressure, the groundwater
pressure at the bottom of the clay layer should be calculated based on the hydraulic head
of PL–line 2. Of course the water pressure at the top and at the bottom of the coarse sand
layer should be calculated based on the hydraulic head of PL–line 2. This will result in the
Pl-lines per layer window shown in Figure 10.8.

Figure 10.8: PL-lines per Layer window

26. Click OK to confirm.
27. The geometry can be tested by clicking Geometry on the menu bar and selecting Check
Geometry. If the geometry is entered properly, the message Geometry has been tested
and is OK appears.
28. Click OK to close this window.
10.5

Soil behavior
Strength of soil layers is dependent on the drained or undrained behavior of soil layers during
application the drilling fluid pressure. Depending on the permeability of the soil layer, the soil
will behave drained or undrained. The Coarse Sand layer is well permeable so that the excess
water pressure due to the drilling fluid pressures will dissipate easily. The strength of this soil
layer can be calculated using the drained (effective) strength parameters effective cohesion
(c) and angle of internal friction (ϕ). In case of undrained behavior in the impermeable Soft
Organic Clay layer, the strength of the soil can be calculated using the undrained strength
parameter undrained cohesion (cu ).
The soil load on the pipeline after finishing the installation is dependent on the soil pipeline
interaction, which is in turn largely dependent on the soil behavior. In D-G EO P IPELINE it is assumed that the pipeline remains fixed at the specified location and that there’s no settlement
of the soil layers below the pipeline. This assumption allows D-G EO P IPELINE to perform a relative simple pipe stress analysis based on a reduced soil load due to arching. As described in
section 10.2, arching develops completely in incompressible soil layers, while in compressible
layers the reduced soil load on the pipeline is higher due to compression of the soil next to the
pipeline.
29. Click GeoObjects and select Boundaries Selection on the menu bar to open the Boundaries Selection window for specification of the soil behavior.
30. Choose the boundary between the undrained and drained layer on top of layer number
<1> (Figure 10.9). This choice results in drained behavior of layer number 1.
31. Choose the boundary between the compressible and incompressible layer on top of layer
number <1>. This choice results in full development of arching in layer number 1 while in
layer number 2 arching is not fully developed.

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32. Click OK to close this window.

Figure 10.9: Boundaries Selection window

10.6

Calculated reduced soil load for pipe stress analysis
The layered soil sequence results in a different reduced neutral soil load at different depths.
Due to the compressible top layer, the reduced neutral soil load increases considerable with
increasing depth (Figure 10.10). In the sand layer, the reduced neutral soil load reduces due
to the full development of arching.

Figure 10.10: The effect of arching with increasing depth (Meijers and De Kock, 1995)

33. To start the calculations, click Calculation and select Start on the menu bar or press the
function key F9.
34. Click Results and select Report on the menu bar to look at the results of the pipe stress
analysis.

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Figure 10.11: Report window, Calculation Pulling Force

10.7

Calculated drilling fluid pressures
The existence of soft organic soil layer with low strength and high deformability characteristics
influences the results of the maximal allowable drilling fluid pressures.
35. Click Results and select Drilling Fluid Pressure Plots on the menu bar to open the Drilling
Fluid Pressure window (Figure 10.12) and to look at the results of the drilling fluid pressure
calculations for the pilot drilling.
The graph shows the maximum allowable pressures (upper limit related to soil cover and lower
limit related to deformation of the borehole) and the minimal required drilling fluid pressure for
transportation of the cuttings. Notice that for the pilot stage the minimal allowable drilling
fluid pressure is higher than the maximal allowable drilling fluid pressure at the last part of the
upward bend of the drilling. This means that the risk of a blow out is present, so that measures
are required.

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Figure 10.12: Drilling Fluid Pressures window

36. Click on the tabs Prereaming and Reaming and pullback operation to look at the results of
the other drilling stages.
37. Close the window to return to the main menu.
10.8

Drilling fluid pressure and groundwater pressure
During the stages of horizontal directional drilling the borehole is filled with drilling fluid. The
drilling fluid has a certain unit weight, which is largely dependent on the initial unit weight of the
drilling fluid and the amount of cut soil material in the drilling fluid. If the borehole is located
in soil layers with an artesian water pressure (aquifers), the risk of leakage of groundwater
through the borehole to the surface exists. The leakage of groundwater will result in flow of
water through the borehole, which in turn will lead to borehole instability (when the drilling
fluid is flown out of the borehole located in coarser granular layers). This risk is automatically
assessed when a D-G EO P IPELINE calculation is performed.
38. Click Results and select Report on the menu bar to watch the results of leakage assessment in paragraph 3.2 (equilibrium between drilling fluid pressure and pore pressure).
Notice that the artesian water pressure is higher than the drilling fluid pressure so that
measures against leakage are required (Figure 10.13).

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Figure 10.13: Report window, Equilibrium between drilling fluid pressure and pore pressure

10.9

Conclusion
In this tutorial, a layered soil sequence has been modeled and the drilling fluid pressures have
been calculated. Using the table called Equilibrium between drilling fluid pressure and pore
pressure in the D-G EO P IPELINE report, it can be concluded if the drilling fluid pressures are or
are not sufficient.

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11 Tutorial 4: Exporting soil mechanical data for an extended stress
analysis
This exercise considers the installation of a polyethylene pipeline by using the horizontal directional drilling technique. The exercise focuses on the calculation of soil mechanical parameters for an extended pipe stress analysis. A settlement calculation forms also part of the
exercise.
The objectives of this tutorial are:

To calculate the soil mechanical parameters for an extended pipe stress analysis;
To perform a settlement calculation;
To export the soil mechanical parameters.
The following module is needed:

D-G EO P IPELINE Standard module (HDD)
License for D-S ETTLEMENT (formerly known as MSettle)
This tutorial is presented in the file Tutorial-4.dri.
Introduction to the case
In D-G EO P IPELINE it is assumed that the pipeline remains fixed at the specified location and
that there’s no settlement of the soil layers below the pipeline. No temperature effects are
taken into account in D-G EO P IPELINE. Therefore a relative simple pipe stress analysis can be
performed.

0m
40
R=

exit: X= 190m

In case compressible soil layers are present below the pipeline and an additional load is
carried out on theses compressible soil layers, settlement can be expected. If settlement
of the layers below the pipeline occurs in most cases, an extended pipe stress analysis is
required. The extended pipe stress analysis can not be performed using D-G EO P IPELINE, but
should be carried out using other software. For instance SCIA pipeline can be used for such
an analysis.
entry: X= 90m

11.1

PL-line 2

+8m
+5m

15º

soft organic clay

15º

PL-line 1

0m
-5m

pipeline
-15m

silty sand

Figure 11.1: Pipeline configuration for Tutorial 4

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Vertical displacement of soil below and around the pipeline that occurs after installation is an
important factor in assessing the stresses in the pipeline. Settlement may be entered manually
if the vertical settlements results are available. For more accurate results, D-G EO P IPELINE
can use the D-S ETTLEMENT computer program (formerly known as MSettle) without additional
input. Settlement deals with soil compaction due to imposed loading. In D-G EO P IPELINE the
loading consists of an extra layer as created in the geometry. The calculation of the settlement
is performed externally by D-S ETTLEMENT, the settlement calculation program of the Deltares
Systems tools. Details on the calculation of settlement are beyond the scope of this manual,
a thorough description can be found in the user manual of D-S ETTLEMENT (Deltares).
Table 11.1: Settlement parameters (acc. Koppejan) of the soil layers (Tutorial 4)

Over-consolidation ratio
Primary compression coefficient below Pc
Primary compression coefficient above Pc
Secondary compression coefficient below Pc
Secondary compression coefficient above Pc

Coarse sand
1.3
109
109
109
109

Soft organic clay
1.3
40
10
160
35

This tutorial is based on continuation of the file used in Tutorial 3 (chapter 10).
1. Click File and select Open on the menu bar to open the Open window.
2. Select the file Tutorial-3 and click the Open button.
3. ClickFile and select Save as on the menu bar to open the Save As window and rename
the file into .
4. Click the Save button to save the file for Tutorial 4.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and for Title 1
and Title 2 respectively in the Identification tab.
7. Click OK.
11.2

Settlement model
Settlement calculations can be performed using the in the Netherlands often used Koppejan
model or the more recent developed Isotache model which is based on Terzaghi’s settlement
model.
8.
9.
10.
11.

Click Project and select Model on the menu bar to open the Model window (Figure 11.2).
Select the Horizontal directional drilling method and mark the Use settlement check-box.
Select the Koppejan model.
Click OK to confirm the choice.

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Figure 11.2: Model window

11.3

Geometry of the longitudinal cross section
This tutorial considers a layered soil sequence described in Tutorial 3 (chapter 10). In the
longitudinal cross section, a load (soil mass) has to be defined.
12. Switch to the Geometry tab in the View Input window to edit the existing soil layer sequence.
from the Edit sub-window to draw an additional layer (soil
13. Select the Add polyline icon
mass) on top of the existing soil layers with coordinates given in Table 11.2.
Table 11.2: Coordinates of the top of the soil mass

X coordinate [m]
-75
-60
30
45

Z coordinate [m]
5
10
10
5

14. Quit editing by clicking the right mouse button.
15. To check or modify the added points, select a point by clicking the left mouse button. The
point will become a red square.
16. Click the right-hand mouse button and select Properties. In the window displayed (Figure 11.3), the co-ordinates can be checked and modified if needed.

Figure 11.3: Point window

17. Select the Automatic regeneration of geometry on/off icon
from the Tools sub-window
so that the geometry as shown in Figure 11.4 appears. If the Automatic regeneration of
geometry icon already is selected, click on the Edit
icon to regenerate the geometry.
Notice that the soil mass is located on the left side above the section where the pipeline is
located in the Soft Organic Clay layer.

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Figure 11.4: View Input window, Geometry tab

11.4

Soil layer properties
The settlement properties of the soil layers in the layered soil sequence should now be specified. The properties of the soil mass should be entered too.
18. Click Soil and select Materials on the menu bar to open the Materials window.
19. Select the soil name Silty Sand in the left column of the Materials window and enter the
properties given in Figure 11.5.
20. Select the soil name Coarse Sand and enter the Settlement Koppejan data given in Table 11.1.
21. Select the soil name Soft Organic Clay and enter the Settlement Koppejan data given in
Table 11.1.
22. Finish the input of soil data by clicking OK.

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Figure 11.5: Materials window

11.5

Finishing the geometry of the longitudinal cross section
The defined soil properties have to be assigned to the drawn geometry of the longitudinal
cross section (groundwater levels are assigned already). The assignments can be carried out
by clicking geometry and choosing the subsequent described options on the menu bar.
23. Click Geometry and select Layers on the menu bar to open the Layers window to assign
the soil properties to the soil layers in the longitudinal cross section.
24. Click on the tab Materials.
25. Assign the soil properties given in Figure 11.6.
26. Click OK to confirm the assignments.

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Figure 11.6: Layers window, Materials tab

11.6

Calculated soil mechanical parameters in export file
The calculation of the settlement of the soil layers below the pipeline is performed externally by D-S ETTLEMENT (formerly known as MSettle), the settlement calculation program of
the Deltares Systems tools. Therefore, the directory where the program is installed must be
given:
27. Click Tools on the menu bar and select Program Options to open the Program Options
window. Then select the Locations tab (Figure 11.7).
28. If needed, change the directory where the Settlement program is installed by clicking the
Browse button.
29. Click OK to confirm.

Figure 11.7: Program Options window, Locations tab

The other soil mechanical parameters are calculated automatically in D-G EO P IPELINE.

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30. To start the calculations click Calculation and select Start on the menu bar to or press
the function key F9. Ignore the message of Cu values of 0 above the drained undrained
boundary.
31. Click Results and select Report on the menu bar to look at the results of the settlement
calculation in paragraph 3.1 (Figure 11.8) and the calculation of the soil mechanical parameters in paragraph 4.1.

Figure 11.8: Report window, Settlements along pipeline

32. Click File and select Export Results as csv. . . on the menu bar to create an export file with
the soil mechanical parameters.
33. Click on the Save button. The export file is saved on the same directory as Tutorial 4 and
can be opened using the Excel program for example (see Figure 11.9).

Figure 11.9: Content of the export file for Tutorial 4

The export file contains:

Horizontal soil data
Vertical soil data
Soil data for friction
Data of pipeline

For more information, refer to section 3.1.2.

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11.7

Conclusion
A pipe stress and settlement analysis has been performed for a polyethylene pipe in a layered
soil. The inputs and results of this calculation have been exported in a csv file in order to
perform an extended stress analysis using an other program such as SCIA pipeline.

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12 Tutorial 5: Drilling with a horizontal bending radius
This fifth exercise considers installation of a polyethylene pipeline by using the technique
horizontal directional drilling. The exercise focuses on a horizontal bending radius in the
design of the drilling line.
The objectives of this tutorial are:

To schematize a horizontal bending;
To calculate pulling forces in the horizontal bending;
To perform a pipe stress analysis for the design with a horizontal bending radius.
The following module is needed:

D-G EO P IPELINE Standard module (HDD)
This tutorial is presented in the file Tutorial-5.dri.
12.1

Introduction to the case
A horizontal bending radius in the design drilling line is observed more frequent. Often the
horizontal bend is part of one of the vertical bending radii. In case the horizontal bending
radius coincides with part of a vertical bending radius, a combined 3-dimensional bending
radius is formed. For the design of the horizontal directional drilling line, the pull back force and
the strength calculation it is necessary to determine the value of the 3 dimensional bending
radius.
The value of the three dimensional bending radius can be calculated as follows:

s
Rcombi =

Rh2 × Rv2
Rh2 + Rv2

(12.1)

where:

Rcombi
Rh
Rv

is the combined bending radius, in m;
is the horizontal bending radius, in m;
is the vertical bending radius, in m.

The combined bending radius is used to calculate the pulling force during the pull back operation and is used in the pipe stress analysis in D-G EO P IPELINE.

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Top view

R= 1500m

70m

0m
40
R=

exit: X= 190m

entry: X= 90m

70m

PL-line 2

+8m
+5m

15º

soft organic clay

15º

PL-line 1

0m
-5m

pipeline
-15m

silty sand

Figure 12.1: Pipeline configuration of Tutorial 5

This tutorial is based on continuation of the file used in Tutorial 3 (chapter 10).
1. Click File and select Open on the menu bar to open the Open window.
2. Select Tutorial-3 and click the Open button to open the file.
3. Click File and select Save as on the menu bar to open the Save As window and rename
the file into .
4. Click the Save button to save the file for Tutorial 5.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and
for Title 1 and Title 2 respectively in the Identification tab.
7. Click OK.
12.2

Pipeline Configuration
The horizontal bend must be specified in the pipeline configuration window.
8. Click Pipe and select Pipeline Configuration on the menu bar to open the Pipeline Configuration window.

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Figure 12.2: Pipeline Configuration window

9. Enter the values given in Figure 12.1.
10. Click OK to confirm.
11. Look at the entered horizontal bending on the Top View tab of the View Input window
(Figure 12.3).
12. Look at the longitudinal cross section on the Input tab of the View Input window and notice
the elongation of the longitudinal cross section. Therefore it is recommended to check, in
case of projects with changing 3D pipeline configurations, if the soil layer sequence in the
longitudinal cross section is still reliable (according to the soil investigation data).

Figure 12.3: View Input window, Top View tab

Note: The horizontal bending is indicated with a black bold line in the longitudinal cross
section (Figure 12.4).

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Figure 12.4: View Input window, Input tab

12.3

Calculation of the pulling force and pipe stress analysis
The results of the pulling force calculation are shown in the D-G EO P IPELINE report which is
created automatically after finishing the calculations.
13. To start the calculations click Calculation and select Start on the menu bar or press the
function key F9.
14. Click Results and select Report n the menu bar to look at the results of the pulling force
calculations. The results can be found on paragraph 5.3 (Figure 12.5).
Note the increase in pulling force due the horizontal bending radius compare to the case
without bending (see results of Tutorial 3 in Figure 10.11).

Figure 12.5: Report window, Calculation Pulling Force

In paragraph 5.1 (Figure 12.6), the data for the pipe stress analysis is given. The value of the

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minimal bending radius is equal to Rmin = 386 m.

Figure 12.6: Report window, General Data

The minimum bending radius is used to calculate the stresses in the pipeline. In the assessment table in paragraph 6.3 of the report, the influence of a smaller bending radius is visible:
higher axial and tangential stresses in both the installation stages and the operational stage
after installation.
12.4

Conclusion
This tutorial models a horizontal bending in the pipeline configuration. The calculated pulling
forces increase compare to the case without horizontal bending presented in Tutorial 3.

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13 Tutorial 6: Installation of bundled pipelines
This sixth tutorial considers installation of a bundle consisting of five polyethylene pipelines by
using the technique horizontal directional drilling. The exercise focuses on the background of
the automatic bundle calculation in D-G EO P IPELINE.
The objectives of the exercise are:

To calculate the drilling fluid pressures for the pull back operation;
To calculate the pulling force on the bundled pipelines during the pull back operation;
To perform an automatic pipe stress analysis for the pipelines in the bundle.
The following module is needed:

D-G EO P IPELINE Standard module (HDD)
This tutorial is presented in the file Tutorial-6.dri.
13.1

Introduction to the case
The calculations required for the installation of bundled pipelines using the horizontal directional drilling technique are rather similar to those for the installation of a single pipeline.
Differences exist in the calculations:

For the minimal required drilling fluid pressure during the pull back operation
For the pulling force during the pull back operation
For the pipe stress analysis (differences in assumptions)
Ad 1) Of course the available space for the back flow of the drilling fluid is different in case of a
bundled pipeline. For calculation of the minimal required drilling fluid pressure, D-G EO P IPELINE
assumes flow of the drilling fluid

through the space in between the bundle and the borehole wall
and through the space in the bundle, in between the pipelines.
Ad 2) Important parameters for the calculation of the pulling force during the pullback operation
are the total effective weight of the (filled) pipelines in the bundle and the total stiffness of the
bundle which determines the soil reaction force in curved sections of the drilling line. In
D-G EO P IPELINE the pulling force is calculated for an equivalent pipeline with the weight and
stiffness parameters of the bundled pipelines.

EIeq =
Gtot =

i=1
X

Ei Ii

n
i=1
X
n

π 2
π
2
D − (D0;i − 2dn;i ) × γi
4 o;i 4

(13.1)

(13.2)

where:

n
Do;i
dn;i
γi
Ei

is the total number of pipelines in the bundle;
is the outer diameter of pipeline i, in m;
is the wall thickness of pipeline i, in m;
is the unit weight of pipeline i, in kN/m3 ;
is the Young’s modulus of pipeline i, in kN/m2 ;

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Ii
Ieq

is the moment of inertia of pipeline i, in m4 ;
is the moment of inertia of the bundle, in m4 .

The calculated pulling force is acting on all the pipelines in the bundle. The magnitude of the
pulling force of a pipeline in the bundle is derived by dividing the total pulling force over the
cross section area of the wall of the pipelines with equal stiffness.
In case the stiffness of the pipeline materials is significantly different (for example a combined
bundle of steel and PE pipelines), a different approach is applied. In addition to the previous
described dividing procedure, the total pulling force is assigned to the stiffer pipeline (steel
pipeline).
Ad 3) The pipe stress analysis for a pipeline in the bundle is quite similar to the pipe stress
analysis for a single pipeline in the bore hole. The only difference in the pipe stress analysis
is the contact between the pipeline and the surrounding soil (single pipeline) and the contact
between the pipeline and the adjacent pipelines (bundle). Therefore the load angle and the
bedding angle should be adapted in case of a bundled pipeline. In this tutorial angle values
of 30 degrees are assumed and entered manually.
Table 13.1: Pipes properties (Tutorial 6)

Material quality
Young’s modulus (short term)
Young’s modulus (long term)
Allowable strength (short term)
Allowable strength (long term)
Tensile factor
Outer Diameter
Wall thickness
Unit weight pipe material
Design pressure
Test pressure
Temperature variation

[N/mm2 ]
[N/mm2 ]
[N/mm2 ]
[N/mm2 ]
[-]
[mm]
[mm]
[kN/m3 ]
[Bar]
[Bar]
[◦ C]

Pipe 1
PE80
1000
200
10
8
0.65
400
36.4
9.54
4
5
5

Pipe 2
PE80
1000
200
10
8
0.65
160
12.3
9.54
4
5
5

This tutorial is based on continuation of the file used in Tutorial 5 (chapter 12).
1. Click File and select Open on the menu bar to open the Open window.
2. Select Tutorial-5 and click the Open button to open the file.
3. Click File and select Save as on the menu bar to open the Save As window and rename
the file into .
4. Click the Save button to save the file for Tutorial 6.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and for Title 1
and Title 2 respectively in the Identification tab.
7. Click OK.

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13.2

Product Pipe Material Data
The dimensions and the properties of the product pipes in the bundle should be specified.
8. Click Pipe and select Product Pipe Material Data on the menu bar to open the Product
Pipe Material Data window for specification of the dimensions and properties of the product
pipes in the bundle.
9. Change the following values for Pipe 1 in the fields on the right side of the window (Figure 13.1).

Figure 13.1: Product Pipe Material Data window

on the left side of the window to declare a pipeline with the
10. Click on the Add button
name .
11. Enter the values for Pipe 2 (Table 13.1), in the fields on the right side of the window.
12. Click on the Add button on the left side of the window three times to add three more pipes.
Notice that the material properties of Pipe 2 are automatically copied to these pipes.
13. Use the Rename button on the left side of the window to rename the new pipes into
, and .
14. Click on OK to confirm the specified product pipe material data.
The bundle now consists of five pipes:

13.3

Pipe nr.
Pipe nr.
Pipe nr.
Pipe nr.
Pipe nr.

1:
2:
3:
4:
5:

400 mm SDR 11 PE 80
160 mm SDR 13 PE 80
160 mm SDR 13 PE 80
160 mm SDR 13 PE 80
160 mm SDR 13 PE 80

Drilling Fluid Data
The properties of the drilling fluid and the operation parameter values should be specified for
the bundle.

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15. Click Pipe and select Drilling Fluid Data on the menu bar to open the Drilling Fluid Data
window for specification of properties of the drilling fluid.
16. Enter the values of Figure 13.2 for installation of the bundle. The bedding and the load
angle are 30 degrees since contacts in between the pipelines are expected. These values
are used in the pipe stress analysis to determine the moment coefficients. The values for
the special pipe stress analysis do not have to be entered.
17. Click on the OK button to confirm the input of the specified value.
Note: The equivalent diameter
√ of the bundle is calculated automatically. The equivalent
diameter amounts to Deq = 0.42 + 4 × 0.162 = 0.512 m.

Figure 13.2: Drilling Fluid Data window

13.4

Engineering Data
Since the engineering properties for a bundle are different from single pipeline installation
properties, values of the engineering properties have to be changed.
18. Click Data and select Engineering data on the menu bar to select the Engineering Data
window. This will result in the window shown in Figure 13.3.
19. Do not fill the pipe on the rollers and enter the values of Figure 13.3 in the standard input
window.
20. Click on the OK button to confirm the input of the specified values.

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Figure 13.3: Engineering Data window

13.5

Factors
D-G EO P IPELINE performs the calculations of the drilling fluid pressures according the Dutch
regulations described in the NEN 3650 series (NEN, 2012a,b,c) and in NEN 3651 (NEN,
2012d). The safety philosophy described in the NEN 3650-1 Annex B and D is applied on the
calculations.
21. Click Defaults and select Factors on the menu bar to select the contingency and safety
factors window for watching the default values or adapting this values.
22. Due to the pull back of the bundled pipelines the risk on higher pulling forces than calculated is present. According to the NEN 3650-1 (article E.1.2.3), the contingency factor on
the pulling force should be 1.8. Change this value into <1.8> as shown in Figure 13.4.
23. Click OK to confirm.

Figure 13.4: Factors window

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13.6

Results
The results of the pulling force calculation are shown in the report which is created automatically after finishing the calculations.
24. To start the calculations click Calculation and select Start on the menu bar to tart the
calculation or press the function key F9.
25. Click Results and select Report on the menu bar to view the results of the pulling force
calculations. The results can be found in paragraph 5.3 (Figure 13.5).

Figure 13.5: Report window, Calculation Pulling Force

Notice that the total pulling force is divided over the pipelines in the bundle for pipe stress
analysis purposes. The pipe stress analysis per pipeline is described in the paragraphs 6 to
10.

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14 Tutorial 7: Face support pressure for micro tunneling
This seventh tutorial considers installation of a gas pipeline crossing underneath a railway by
using micro-tunneling. The gas pipeline consists of steel pipe sections. The exercise focuses
on the basic calculation set up for micro-tunneling in D-G EO P IPELINE.
The objectives of the exercise are:

To make a schematization of the pipeline installation by micro tunneling;
To evaluate the minimal required and maximal allowable shield pressure at the face of
the tunneling machine.
The following modules are needed:

D-G EO P IPELINE Standard module (HDD)
Micro Tunneling module
The result of this tutorial is presented in the file Tutorial-7.dri.
14.1

Introduction to the case
Micro-tunneling in general uses a remote controlled micro tunnel boring machine (MTBM).
The micro tunnel usually starts horizontal at a certain level below the surface. Drive and
reception shafts are created for the MTBM. In the drive shaft a jacking frame and MTBM are
installed. The jacks will push the pipe section elements section by section ahead towards
the reception shaft. The MTBM is at the front of the advancing micro tunnel. As the length
of the advancing micro tunnel increases so do the friction forces along the pipe segments.
Lubrication fluid may be applied for lubrication.

Figure 14.1: Pipeline configuration for Tutorial 7

Very often at the face of the MTBM drilling fluid is used for, soil removal and front stabilization.
Careful planning and monitoring of the face support pressures is required: When the pressure
is excessive this may cause a blow out; if the pressure is too low collapse of the soil in at
the drilling front may cause excessive subsidence. The pipeline configuration is shown in
Figure 14.1.

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The soil properties of the silty sand layer are provided in Table 14.1.
Table 14.1: Properties of the silty sand layer (Tutorial 7)

Dry unit weight
Wet unit weight
Cohesion
Angle of internal friction
Undrained strength top
Undrained strength bottom
E modulus top
E modulus bottom
Adhesion
Friction angle (Delta)
Poisson’s ratio

[kN/m3 ]
[kN/m3 ]
[kN/m2 ]
[◦ ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[◦ ]
[-]

18
20
0
30
0
0
10000
15000
0
20
0.35

The pipeline material used in this tutorial is a steel 240 with the properties given in Table 14.2.
Table 14.2: Properties of steel material (Tutorial 7)

Pipe material
Outer diameter
Overcut
Wall thickness
Young’s modulus
Unit weight pipe material

[mm]
[mm]
[mm]
[N/mm2 ]
[kN/m3 ]

Steel 240
1200
15
22.4
205800
78.50

This tutorial starts with the selection of the pipeline installation model.
14.2

Model selection
The micro tunneling model must be selected to carry out the current tutorial.
noitemsep
1. Click File and choose New on the menu bar to start a new project.
2. In the New File window select the option New geometry to start. This will result in an
empty geometry.
3. Save the project by clicking Save As in the File menu and by entering as
project name.
4. Click Save to close this window.
5. On the menu bar, click Project and then choose Model to open the Model window (Figure 14.2).
6. Select Micro tunneling and click OK.

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Figure 14.2: Model window

7. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
8. Fill in and
for Title 1 and Title 2 respectively in the Identification tab.
9. In the other tab of the Project Properties window, modify (if not already done) some defaults
values according to Figure 14.3 in order to make the graphical geometry more understandable.
10. Click OK.

Figure 14.3: Project Properties window, View input tab

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14.3

Geometry
Firstly, the geometry of Figure 14.1 needs to be given in D-G EO P IPELINE. In order to do this,
the following actions should be performed:
11. First enlarge the dimensions of the geometry window by selecting the left boundary by
clicking the left mouse button, then click the right button and select Properties. This will
result in the coordinate window for the left boundary as shown in Figure 14.4. Enter coordinate X of <100 m>.

Figure 14.4: Left Limit window

12. Repeat the previous described actions for the right boundary and shift the boundary to
coordinate X of <200 m>. The width in between the left and the right boundary is now
300 m.
13. Select the drawing button Zoom limits
from the Tools panel so that the drawn geometry
appears in the center of the screen.
14. Unselect the drawing button Automatic regeneration of geometry on/off
from the Tools
panel.
15. Select the drawing button from the Edit panel Add single line
to draw the surface line of
the longitudinal cross section of the horizontal directional drilling and position the straight
surface line at Z = 5 m. Use the right mouse button to finish the line.
16. Select again the drawing button Add single line to draw the lower boundary of the longitudinal cross section of the horizontal directional drilling and position the straight lower
boundary line at Z = –40 m. Use the right mouse button to finish the line.
17. Select the drawing button Automatic regeneration of geometry on/off from the Tools panel
so that the geometry as shown in Figure 14.5 appears.
18. Select the drawing button Add pl-line(s)
from the Edit panel and position the level of the
groundwater at coordinate Z = 0 m. Use the right mouse button to finish the line. The blue
dashed line represents the groundwater line (PL line).

Figure 14.5: View Input window, Geometry tab

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14.3.1

Soil layer properties
The properties of the soil layers should be specified in the menu materials, which can be
entered by clicking soil. In this tutorial only one soil layer is considered.
19. Click Soil and select Materials on the menu bar to open the Materials window (Figure 14.6)
and enter the soil data.
20. Add a new material by choosing Add button below the materials list on the left side of the
window with the new .
21. Enter the soil data as given in Table 14.1.
22. Finish the input of soil data by clicking OK.

Figure 14.6: Materials window

Phreatic Line
23. On the Geometry menu, select Phreatic Line to open Phreatic Line window (Figure 14.7)
in which the phreatic line for calculation of the groundwater pressures can be selected.
24. Choose PL–line nr. <1> (only one phreatic line is available) and click OK.

Figure 14.7: Phreatic Line window

14.3.3

Layers
25. Click Geometry and select Layers on the menu bar to assign the soil properties to the soil
layers in the longitudinal cross section. To assign a material to a layer, select the Material
tab.

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26. Assign the properties of the defined layer Silty Sand to layer nr 1 in the longitudinal cross
section. The available soil layers with defined properties are shown in left column of the
materials window. The layers in the longitudinal cross section are shown in the right column
of the materials window. The defined properties are assigned to layer nr 1 by clicking the
arrow in between the columns. This will result in the Material tab shown in Figure 14.8.

Figure 14.8: Layers window, Materials tab

27. Click OK to quit the window and return to the geometry window to watch the change of
layer name in the legend.
14.3.4

PL-Lines per Layers
28. Click Geometry and select PL–lines per Layers on the menu bar to open the PL–lines
per Layer window (Figure 14.9) in which the defined PL–lines to the soil layers in the
longitudinal cross section can be defined. This window contains the information for the
calculation of the groundwater pressure distribution. In this tutorial only one PL-line is
defined. The groundwater pressure at the top of the silty sand layer and the bottom of this
layer should be calculated based on the hydraulic head of PL-line 1.
29. Click OK to close the window.

Figure 14.9: PL-lines per Layers window

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14.3.5

Check Geometry
30. The geometry can be tested by clicking Geometry and selecting Check Geometry on
the menu bar. If the geometry is entered properly, the message shown in Figure 14.10
appears.
31. Click OK to close the window.

Figure 14.10: Check Geometry window

14.4

Pipeline Configuration
The pipe is installed in the silty sand layer starting and ending at respectively the start and
reception shaft at a level 11 m below surface. As the pipe trajectory is horizontal, the smallest
angle of entry allowed by D-G EO P IPELINE is defined, i.e. 0.1 degree. A small bending radius
restricts the curved part of the pipe near the entry and exit of the pipe, thus the rest of the
pipe will be exact along the lowest level of the pipe.
32. Click Pipe from the menu and select Pipeline Configuration to open the Pipeline Configuration window.
33. Enter the values as presented in Figure 14.11.

Figure 14.11: Pipeline Configuration window

34. Click OK to confirm.
35. Now examine the micro tunnel trajectory in the Input tab (Figure 14.12) and Top View tab
of the View Input window.

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Figure 14.12: View Input window, Input tab

14.5

Pipe Material Data
The pipe material of the pipe which will be installed by micro tunneling is chosen. The characteristics of the pipe must be specified as well.
36. Click Pipe from the menu and select Product Pipe Material Data to open the Product Pipe
Material Data window.
37. Enter the values as presented in Figure 14.13.

Figure 14.13: Product Pipe Material Data window

The effect of the overcut on the radius of the pipe is explained in tutorial 9 (chapter 16).
14.6

Soil behavior
The strength of soil layers is dependent on the drained or undrained behavior of soil layers
during application the drilling fluid pressure at the front of the MTBM. Depending on the permeability of the soil layer, the soil will behave drained or undrained. A Sand layer is a well
permeable so called drained frictional material. The strength of this soil layer can be calculated using the drained (effective) strength parameters effective cohesion (c) and angle of
internal friction (ϕ). In case of undrained behavior in other soil types, the strength of the soil

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can be calculated using the undrained strength parameter undrained cohesion (cu ).
38. Click GeoObjects and select Boundaries Selection on the menu bar to open the Boundaries Selection window for specification of the soil behavior.
39. Choose the boundary between the undrained and drained layer on top of layer nr <1>
(Figure 14.14). This choice results in drained behavior of layer nr 1.
40. Choose the boundary between the compressible and incompressible layer on top of layer
nr <1>. This choice results is used for the calculation of the soil mechanical parameters.
Compressible layers yield higher soil loads on the pipeline due to incomplete arching.
41. Click OK to close this window.

Figure 14.14: Boundaries Selection window

14.7

Calculation Verticals
The locations in the longitudinal cross section at which a calculation should be carried out
must be specified by the user. The user is able to perform calculations at uniform distances
along the longitudinal cross section but is also able to perform more calculations at short
distances at locations of interest.
42. Click GeoObjects and select Calculation Verticals on the menu bar to select the Calculation
Verticals window for specification of the calculation locations along the longitudinal cross
section.
43. Choose the Automatic generation of L co-ordinates option on the right side of the window
and choose the following values: <–80 m> for First, <180 m> for Last and <20 m> for
Interval.
44. Click on the Generate button and watch the result of automatic vertical generation on
the left side of the Calculation Verticals window. This will result in the window shown in
Figure 14.15.
45. Click OK to confirm the selected verticals and switch to the input window to watch the
location of the verticals in the longitudinal cross section.

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Figure 14.15: Calculation Verticals window

14.8

Engineering Data
46. Select Engineering Data from the Pipe menu bar to open the Engineering Data window.
47. Enter the values as given in Figure 14.16.

Figure 14.16: Engineering Data window

The maximum allowable thrust force is usually specified by the manufacturer of the pipe. The
volume loss determines the subsidence at the surface.

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14.9

Results: Operation Parameter Plots
The micro-tunneling machine changes the stress conditions in the soil. The deviations from
the original stress conditions (Figure 14.17) are largely determined by the size of the overcut
and the applied shield. Small deviations from the original conditions are acceptable as the
stability of soil adjacent to the micro-tunneling machine is maintained. A relative low face
support pressure may lead to collapse of the soil in front of the shield, which in turn may lead
to subsidence of the surface or to settlement of soil layers below a construction or pipeline.
A relatively high face support pressure can lead to a blow out of drilling fluid or may lead to
heave of the surface.

Figure 14.17: Schematization of stress condition for micro-tunneling

While drilling the shield pressures have to be kept between certain limits. To prevent the
possibility of collapse in of the soil in front of the micro tunneling shield, causing subsidence,
the soil at the front is kept stable by maintaining a minimal face pressure. Depending on the
soil type the minimal support pressure can be calculated using Jancsecz and Steiner theory
(drained behavior of the soil) (Jancesz and Steiner, 1994), or Broms and Bennermark theory
(undrained behavior of the soil) (Broms and Bennermark, 1967). In this tutorial the soil layer
which consists of silty sand exhibits drained soil behavior.
A maximum support pressure should not be exceeded to prevent uplift of the soil above the
micro-tunneling machine or a blow out of drilling fluid towards the surface. The support pressure, at which the soil deformations are minimal during drilling should be in between the two
limits. At the neutral pressure, the face support pressure is in equilibrium with the current
horizontal soil pressure.
48. To start the calculations click Calculation and select Start on the menu bar or press the
function key F9.
49. Click Results and select Operation Parameter Plots from the menu bar to open the Operation Parameter Plots window.

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Figure 14.18: Operation Parameter Plots window, Face support pressure tab

From the graph (Figure 14.18) it can be observed that for this simple tutorial situation the target
face support pressure during the pipeline installation should be between the determined limits
of the maximum allowable face support pressure and the minimum required face support
pressure. At the neutral pressure the face support pressure is in equilibrium with the current
horizontal soil pressure.

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15 Tutorial 8: Uplift and thrust forces for micro tunneling
This tutorial concentrates on the installation of a pipeline by using the micro-tunneling technique and is a continuation of the previous tutorial. It considers installation of a gas pipeline
consisting of welded steel pipes. The pipeline crosses underneath a railway by using microtunneling.
The objectives of the exercise are:

To evaluate the thrust force;
To perform a check on the uplift safety.
The following modules are needed:

D-G EO P IPELINE Standard module (HDD)
Micro Tunneling module
This tutorial is presented in the file Tutorial-8.dri.
15.1

Introduction to the case
This tutorial considers a peat layer on top of the existing silty sand layer. The risk on uplift
of the empty pipeline in the peat layer is evaluated. The possibility of an alternative, longer,
micro tunneling trajectory is evaluated in this tutorial. A longer pipe string yields increased
friction forces which could possibly exceed the maximum allowable thrust force of the pipeline
or the jacking frame.

Figure 15.1: Soil layers and pipeline configuration for Tutorial 8

The soil properties are provided in Table 15.1.

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Table 15.1: Properties of the layers (Tutorial 8)

Dry unit weight
Wet unit weight
Cohesion
Angle of internal friction
Undrained strength top
Undrained strength bottom
E modulus top
E modulus bottom
Adhesion
Friction angle (Delta)
Poisson’s ratio

[kN/m ]
[kN/m3 ]
[kN/m2 ]
[◦ ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[◦ ]
[-]

Silty Sand
18
20
0
30
0
0
10000
15000
0
20
0.35

Peat
10.2
10.2
2
15
10
20
1000
1500
2
5
0.45

This tutorial is based on continuation of the file used in Tutorial 7 (chapter 14).
1. Click File and select Open on the menu bar to open the Open window.
2. Select Tutorial-7 and click the Open button to open the file.
3. Click File and select Save as on the menu bar to open the Save As window and rename
the file into .
4. Click the Save button to save the file for Tutorial 8.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and
for Title 1 and Title 2 respectively in the Identification tab.
7. Click OK.
15.2

Geometry of the longitudinal cross section
This tutorial considers a layered soil sequence. The typical Dutch soil sequence of a peat
layer on top of a silty sand layer will be considered. The peat layer is compressible and
exhibits a low permeability, while the sand layer is assumed incompressible and exhibits a
high permeability. The new soil layers should be specified in the geometry window.
8. In the View Input window, switch to the Geometry tab to edit the existing soil layer sequence.
9. Click the Add polyline(s)
button from the Edit panel to draw an additional line which represents the lower boundary of the peat layer on top of the silty sand layer. The coordinates
of the cursor are given in the lower left side of the geometry window. Make the polyline
by clicking on the subsequent co-ordinates (Figure 15.2). Click the right mouse button to
escape from the polyline drawing.

Figure 15.2: Co-ordinates of the lower boundary of the Peat layer (before enlarging the
right limit)

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10. After finishing the polyline, mis-clicks can be corrected using the Edit button: select points
of the polyline by clicking on it with the left mouse button. Once the point is selected
(indicated with a red color), use the right mouse button to select the option Properties. . .
and to correct the co-ordinates of the lower boundary of the peat layer.
11. Change the position of the phreatic groundwater: select both points of the PL line (i.e. blue
dashed line) by clicking on it with the left mouse button, then select the option Properties. . .
and change the co-ordinate into Z = 5 m.
12. Enlarge the dimensions of the geometry window by selecting the right boundary by clicking
the right mouse button, then click the right button and select Properties. . . . This will result
in the coordinate window for the right boundary as shown in Figure 15.3. Enter coordinate
X of <400 m>.

Figure 15.3: Right Limit window

13. Click the Zoom limits
button from the Tools panel so that the drawn geometry appears
in the center of the screen.
15.3

Soil layer properties
The properties of the soil layers in the layered soil sequence should now be specified.
14.
15.
16.
17.

Click Soil and select Materials on the menu bar to enter the soil data.
Select the existing soil material Peat.
Enter the soil data as given in Table 15.1.
Click OK.

Figure 15.4: Materials window

The defined soil properties have to be assigned to the drawn geometry of the longitudinal
cross section. The assignments can be carried out in the Geometry menu.
18. Click Geometry and select Layers on the menu bar to open the Layers window.

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Figure 15.5: Layers window, Materials tab

19. Select the Materials tab.
20. Assign the properties of the defined layer Peat to layer number 2 in the longitudinal cross
section by clicking the Assign icon
in between the left and the right column.
21. Click on the OK button to quit the window and return to the Geometry tab of the View Input
window to look at the change of layers name in the legend (Figure 15.6).

Figure 15.6: View Input window, Geometry tab

22. The geometry can be tested by clicking Geometry on the menu bar and selecting Check
Geometry. If the geometry is entered properly, the message Geometry has been tested
and is OK appears.
23. Click OK to close this window.
15.4

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of the silty sand layer is drained. The strength of this soil layer can be calculated using the
drained (effective) strength parameters effective cohesion (c) and angle of internal friction (ϕ).
In case of undrained behavior in the impermeable Peat layer, the strength of the soil can be
calculated using the undrained strength parameter undrained cohesion (cu ).
The soil load on the pipeline after finishing the installation is dependent on the soil pipeline interaction, which is in turn largely dependent on the soil behavior. As described in section 10.2
arching develops completely in incompressible soil layers, while in compressible layers the
reduced soil load on the pipeline is higher due to compression of the soil next to the pipeline.
24. Click GeoObjects and select Boundaries Selection on the menu bar to open the Boundaries Selection window for specification of the soil behavior.
25. Choose the boundary between the Drained and undrained layers on top of layer number
<1> (Figure 15.7). This choice results in drained behavior of layer number 1.
26. Choose the boundary between the Compressible and uncompressible layers on top of
layer number <1>. This choice results in full development of arching in layer number 1
while in layer number 2 arching is not fully developed.
27. Click OK to close this window.

Figure 15.7: Boundaries Selection window

15.5

Pipeline Configuration
The tunneling length will be increased by changing the entry and exit locations.
28. Click Pipe and select Pipeline Configuration from the menu bar to open the Pipeline Configuration window.
29. Change the X-coordinates of the left and right points to respectively <-90> and <390>
as shown in Figure 15.8.
30. Click OK.

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Figure 15.8: Pipeline Configuration window

15.6

Calculation Verticals
The locations in the longitudinal cross section at which a calculation should be carried out
must be specified by the user. The user is able to perform calculations at uniform distances
along the longitudinal cross section but is also able to perform more calculations at short
distances at areas of interest.
31. Click GeoObjects and select Calculation Verticals on the menu bar to select the Calculation
Verticals window for specification of the calculation locations along the longitudinal cross
section. This will result in the window shown in Figure 15.9.
32. Choose the Automatic generation of L co-ordinates option on the right side of the window
and choose the following values: <–80 m> for First, <380 m> for Last and <20 m> for
Interval.
33. Click on the Generate button and watch the result of automatic vertical generation on the
left side of the Calculation Verticals window.
34. Click OK to confirm the selected verticals and switch to the input window to watch the
location of the verticals in the longitudinal cross section.

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Figure 15.9: Calculation Verticals window

15.7

Engineering Data
35. Select Engineering Data from the Pipe menu bar to open the Engineering Data window.
36. Enter the values as given in Figure 15.10.
37. Click OK.

Figure 15.10: Engineering Data window

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15.8

Results
The schematization of the longitudinal cross section along the pipeline which will be installed
by using micro tunneling is changed. A calculation can now be performed.
38. To start the calculations click Calculation and select Start on the menu bar or press the
function key F9.

15.8.1

Thrust Force
39. Open the Operation Parameter Plots window from the Results menu and select the Thrust
forces tab (Figure 15.11).
This graph shows the calculated thrust force versus the length of pipe jacked into the subsurface. It is easily recognized that the lubricated as well as the dry thrust force exceed the
maximum allowable thrust force as indicated by the manufacturer of the pipe sections.
It should be mentioned that the capacity of the jacks is limited as well. In general the maximum
capacity is about 600 ton (6000 kN) so that for larger lengths intermediate jacks are required.

Figure 15.11: Operation Parameter Plots window, Thrust Force tab

15.8.2

Uplift safety
Since the pipeline is installed in a soft soil layer with a relative low wet density. The uplift
behavior of the empty pipeline should be evaluated. D-G EO P IPELINE calculates the uplift safety
factor fuplift using the following formula:

fuplift =

σv0 + gpipe
guplift

(15.1)

where:

σv0
gpipe
guplift

is the vertical effective stress;
is the buoyancy of the pipe depending on the diameter of the pipeline and the water
level. Partial submerging is taken into account by D-G EO P IPELINE;
is the uplift force.

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40. Select the Safety uplift tab. As can be seen in Figure 15.12, the uplift safety is more than
the required safety factor of 1.

Figure 15.12: Operation Parameter Plots window, Safety uplift tab

The uplift safety appears to be insufficient in the peat layer. The uplift safety factor equals 0.8.
The safety factors are shown in the report in paragraph 4.2.1. The reported table is shown
subsequently.

Figure 15.13: Report window, Uplift Factors section

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16 Tutorial 9: Settlement and soil mechanical parameters for micro
tunneling
This tutorial provides some detail on settlement and calculation of soil mechanical parameters
in D-G EO P IPELINE. For a pipe stress analysis the knowledge of the soil-pipeline interaction is
required. The soil pipeline interaction is described by the soil mechanical parameters. The
vertical displacement (very often settlement) of the layers below and around the pipeline is
one of the soil mechanical parameters.
The objectives of the exercise are:

To calculate the soil mechanical parameters
To calculate the settlements due to construction of an embankment
The following modules are needed:

D-G EO P IPELINE Standard module (HDD)
Micro Tunneling module
License for D-S ETTLEMENT (formerly known as MSettle)
This tutorial is presented in the file Tutorial-9.dri.
16.1

Introduction to the case
The same project as Tutorial 8 (chapter 15) is considered with an additional load carry on the
compressible soil layers (Figure 16.1). Settlement can be therefore expected.

Figure 16.1: Soil layers and pipeline configuration for Tutorial 9

For advanced pipe stress analyses special programs need to be used. These programs need
an advanced set of soil mechanical parameters, provided by D-G EO P IPELINE. The programs
will generate a complete spring model around the pipeline for further analyses. The soil
mechanical parameters provided by D-G EO P IPELINE are:

neutral vertical soil load
passive vertical soil load

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reduced vertical soil load
vertical modulus of sub grade reaction
horizontal modulus of sub grade reaction
ultimate vertical bearing capacity
ultimate horizontal bearing capacity
neutral horizontal soil load
vertical displacement
maximal axial friction
friction displacement

Vertical displacement of soil below and around the pipeline that occurs after installation is an
important factor in assessing the stresses in the pipeline. Settlement may be entered manually
if the vertical settlements results are available. For more accurate results, D-G EO P IPELINE
can use the D-S ETTLEMENT computer program (formerly known as MSettle) without additional
input. Settlement deals with soil compaction due to imposed loading. In D-G EO P IPELINE the
loading consists of an extra layer as created in the geometry. The calculation of the settlement
is performed externally by D-S ETTLEMENT, the settlement calculation program of the Deltares
Systems tools. Details on the calculation of settlement are beyond the scope of this manual,
a thorough description can be found in the user manual of D-S ETTLEMENT (Deltares).
Table 16.1: Settlement parameters (acc. Koppejan) of the soil layers (Tutorial 9)

Over-consolidation ratio (OCR)
Primary compression coeff. below Pc (Cp )
Primary compression coeff. above Pc (Cp ’)
Secondary compression coeff. below Pc (Cs )
Secondary compression coeff. above Pc (Cs ’)

Coarse Sand
1
109
109
109
109

Silty Sand
1.3
109
109
109
109

Peat
1.3
40
10
160
35

This tutorial is based on the geometry made in Tutorial 8.
1. Click File and select Open on the menu bar to open the Open window.
2. Select Tutorial-8 and click the Open button to open de file.
3. Click File and select Save as on the menu bar to open the Save As window and rename
the file into .
4. Click the Save button to save the file for Tutorial 9.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and for Title 1 and Title 2 respectively in the Identification tab.
7. Click OK.
16.2

Settlement
For calculation of settlement a license for D-S ETTLEMENT is required. If this license and software is available the model option Settlement will be available in D-G EO P IPELINE. For this
purpose an embankment that will act as a load is introduced.
Settlement calculations can be performed using the in the Netherlands often used Koppejan
model or the more recent developed Isotache model which is based on Terzaghi’s settlement
model.
8. Click Project and select Model on the menu bar to open the Model window.

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9. Mark the Use settlement check-box and select the Koppejan model (Figure 16.2).
10. Click OK to confirm the choice.

Figure 16.2: Model window

16.3

Geometry of the longitudinal cross section
This tutorial considers a layered soil sequence described in Tutorial 8 (chapter 15). In the
longitudinal cross section, a load (soil mass) has to be defined.
11. Switch to the Geometry tab in the View Input window to edit the existing soil layer sequence.
from the Edit sub-window to draw an additional layer (soil
12. Select the Add polyline icon
mass) on top of the existing soil layers with coordinates given in Table 16.2.
Table 16.2: Coordinates of the top of the soil mass

X co-ordinate [m]
-75
-60
30
45

Z co-ordinate [m]
5
10
10
5

13. Quit editing by clicking the right mouse button.
14. To check or modify the added points, select a point by clicking the left mouse button. The
point will become a red square.
15. Click the right-hand mouse button and select Properties. . . . In the window displayed (Figure 16.3), the co-ordinates can be checked and modified if needed.

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Figure 16.3: Points window

from the Tools panel so that the drawn geometry appears
16. Click the Zoom limits button
in the center of the screen.
17. Select the Automatic regeneration of geometry on/off icon
from the Tools sub-window
so that the geometry as shown in Figure 16.4. If the Automatic regeneration of geometry
icon already is selected, click on the Edit icon
to regenerate the geometry. Notice that
the soil mass is located on the left side above the section where the pipeline is located in
the peat layer.

Figure 16.4: View Input window, Geometry tab

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16.4

Figure 16.5: Materials window

20. Select the soil name Silty Sand and enter the Settlement Koppejan data given in Table 16.1.
21. Select the soil name Peat and enter the Settlement Koppejan data given in Table 16.1.
22. Finish the input of soil data by clicking OK.
16.5

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Figure 16.6: Layers window, Materials tab

16.6

Calculated soil mechanical parameters in export file
The calculation of the settlement of the soil layers below the pipeline is performed externally by D-S ETTLEMENT (formerly known as MSettle), the settlement calculation program of
the Deltares Systems tools. Therefore, the directory where the program is installed must be
given:
27. Click Tools on the menu bar and select Program Options to open the Program Options
window. Then select the Locations tab (Figure 16.7).
28. If needed, change the directory where the Settlement program is installed by clicking the
Browse button.
29. Click OK to confirm.

Figure 16.7: Program Options window, Locations tab

The other soil mechanical parameters are calculated automatically in D-G EO P IPELINE.

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30. To start the calculations click Calculation and select Start on the menu bar to or press
the function key F9. Ignore the message of Cu values of 0 above the drained undrained
boundary.
31. Click Results and select Report on the menu bar to look at the results of the settlement
calculation in paragraph 5.1 (Figure 16.8) and the calculation of the Soil Mechanical Parameters in paragraph 3.1 (Figure 16.9).

Figure 16.8: Report window, Settlements of soil layers below the pipeline

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Figure 16.9: Report window, Soil Mechanical Parameters

32. Click File and select Export Results as csv. . . on the menu bar to create an export file with
the soil mechanical parameters.
33. Click on the Save button. The export file is saved on the same directory as Tutorial 9 and
can be opened using the Excel program for example (see Figure 16.10).

Figure 16.10: Content of the CSV export file for Tutorial 9

The export file contains the following data’s:

General data about the D-G EO P IPELINE project
Pipeline data
Horizontal soil mechanical data at the left and right of the pipe
Vertical soil mechanical data at the top and bottom of the pipe

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Water data
Axial soil data for friction
For more information, refer to section 3.1.2.
16.7

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17 Tutorial 10: Subsidence after micro tunneling
This tutorial provides some detail on subsidence calculations in D-G EO P IPELINE. Subsidence
is related to surface level changes due to excavation of the subsurface by the micro tunneling
machine.
The objectives of the exercise are:

To enter a non linear bore path;
To evaluate the subsidence along the pipeline.
The following modules are needed:

D-G EO P IPELINE Standard module (HDD)
Micro Tunneling module
This tutorial is presented in the file Tutorial-10.dri.
17.1
17.1.1

Introduction to the case
Volume loss along the tunnel excavation
Subsidence is related to the volume loss along the tunnel excavation, e.g. the excess soil
removed by the Micro Tunneling Boring Machine (MTBM). The subsidence mechanism is
described in detail in section 24.3.
To reduce the friction between pipe and wall of the drilling hole, and allow the optional use
of friction reducing fluids, the drilling diameter (R) is usually somewhat larger then the pipe
diameter (r ).

Figure 17.1: Bore hole section

The space created between pipe and wall is called overcut: the distance R − r . See section 4.6.2.2 for entering the overcut. The overcut is generally filled by lubrication fluid depending on the type of lubrication fluid the amount of filling may reduce during or after installation:

Part of the soil above subsides during operation
Compaction/consolidation of the lubrication fluid after installation
The volume loss as percentage of the overcut area is defined as.

Vs = υ π R 2 − r 2

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Note: If one wants to model subsidence due to drilling with a low face support pressure or to
model the influence of densification of granular soils this value may be set above 100%.
The volume loss causing subsidence is in D-G EO P IPELINE based on the expected overcut of
the soil.

Vs =

υπ
(Do + 2 lovercut )2 − Do2
4

(17.2)

where:

υ
VS
Do
lovercut

is the percentage volume loss, in %;
is the differential volume, in m3 /m;
is the pipe diameter, in m;
is the overcut on radius, in m.

The volume created by the over cut is initially filled with lubrication fluid. Within a time period
the lubrication fluid will consolidate and the overburden will subside into space created by
consolidation. The subsidence w at the surface is calculated as follows:

r2
w=√
exp − 2 ,
2i
2πi2
Vs

z < z0

(17.3)

where:

i
z0
z
VS

is the distance in between the center of the tunnel or pipeline and the inflection point
of the trough, in m;
is the depth of the center of the pipeline or tunnel, in m;
is the depth at which the settlement is calculated, in m;
is the differential volume, in m3 /m.

For detail on the shape factor i, see section 24.3.
17.1.2

Modification of the drilling line
A vertical and a horizontal bending radius in the design drilling line for micro tunneling is a
possibility. In this tutorial the drilling line is modified in order to avoid drilling through the peat
layer.

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Figure 17.2: Pipeline configuration of Tutorial 10

Often the horizontal bend is part of one of the vertical bending radii. In case the horizontal
bending radius coincides with part of a vertical bending radius, a combined 3-dimensional
bending radius is formed. For the design of the horizontal directional drilling line, the pull back
force and the strength calculation it is necessary to determine the value of the 3 dimensional
bending radius.
The value of the three dimensional bending radius can be calculated as follows:

s
Rcombi =

Rh2 × Rv2
Rh2 + Rv2

(17.4)

where:

Rcombi is the combined bending radius, in m;
Rh
is the horizontal bending radius, in m;
Rv
is the vertical bending radius, in m.

As has to be mentioned that the current version of D-G EO P IPELINE does not take the soil
reaction forces into account in the curve. Therefore the effect on the friction caused by soil
reaction effects in curves is not considered in D-G EO P IPELINE.
This tutorial is based on continuation of the file used in Tutorial 9 (chapter 16).
1. Click File and select Open on the menu bar to open the Open window.
2. Select and click the Open button to open de file.
3. Click File and select Save As on the menu bar to open the Save As window and rename
the file into .
4. Click the Save button to save the file for Tutorial 10.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.

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6. Fill in and for Title
1 and Title 2 respectively in the Identification tab.
7. Click OK.
8. In the Model window from the Project menu, unselect the option Use settlement.
9. Click OK.
17.2

Pipeline Configuration
The horizontal and vertical curves must be specified in the pipeline configuration window.
10. Click Pipe and select Pipeline Configuration on the menu bar to open the Pipeline Configuration window.
11. Enter the values given in Figure 17.3.
12. Click OK to confirm.

Figure 17.3: Pipeline Configuration window

13. Look at the entered horizontal bending on the Top View tab of the View Input window
(Figure 17.4).
14. Look at the longitudinal cross section on the Input tab of the View Input window and notice
the elongation of the longitudinal cross section. Therefore it is recommended to check, in
case of projects with changing 3D pipeline configurations, if the soil layer sequence in the
longitudinal cross section is still reliable (according to the soil investigation data).

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Figure 17.4: View Input window, Top View tab

Note: The horizontal bending is indicated with a black bold line in the top view (Figure 17.4).

Figure 17.5: View Input window, Input tab

17.3

Material data
After the input of the drilling line, the pipe material is chosen.
15. Click Pipe from the menu and select Product Pipe Material Data to open the Product Pipe
Material Data window.
16. Enter the values as presented in Figure 17.6.

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Figure 17.6: Product Pipe Material Data window

The overcut on the radius amounts to 20 mm, which equals 40 mm on the diameter of the
pipeline.
17.4

Engineering Data
The percentage of volume loss is specified in the Engineering Data window. In this tutorial a
value of 110 % is chosen, so that the effect of drilling with a relative low face pressure (lower
than the neutral face pressure) is incorporated.
17. Select Engineering Data from the Pipe menu bar to open the Engineering Data window.
18. Enter the values as given in Figure 17.7.

Figure 17.7: Engineering Data window

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17.5

Results: Subsidence
To view the calculation results for the subsidence trough as apparent at surface:
19. To start the calculations click Calculation and select Starton the menu bar or press the
function key F9.
20. Click Results and select Subsidence Profiles from the menu bar to open the Subsidence
Profiles window (Figure 17.8).
21. Check the box labeled “Fix axis”, click on the vertical number edit box. Now move through
the verticals by using the up/down arrows on the key board.

Figure 17.8: Subsidence Profiles window for vertical 1

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18 Tutorial 11: Installation of pipeline in a trench
This tutorial considers installation of a concrete sewer by means of trenching. A trench is
made by excavation, the pipe is installed, and the trench is often filled with the soil derived from
the excavation itself. The risks involved during installation include slope failure and bursting of
the trench bottom. After installation uplift of the pipe and pipe deformation due to settlement
are problems that may occur.
The objectives of the exercise are:

To schematize the soil layers with groundwater with different hydraulic heads;
To calculate the soil mechanical parameters for a pipeline in a trench.
The following modules are needed:

D-G EO P IPELINE Standard module (HDD)
Trenching module
This tutorial is presented in the file Tutorial-11.dri.
18.1

Introduction to the case
In this tutorial a simple trench is modeled. The trench passes a small waterway. The geometry
of tutorial 7 forms the base of this tutorial.

Figure 18.1: Geometry of Tutorial 11

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Table 18.1: Layer properties (Tutorial 11)

Dry unit weight
Wet unit weight
Cohesion
Angle of internal friction
Undrained strength top
Undrained strength bottom
E modulus top
E modulus bottom
Adhesion
Friction angle
Poisson’s ratio

[kN/m ]
[kN/m3 ]
[kN/m2 ]
[◦ ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[0]
[-]

Silty Sand
18
20
0
10
0
0
10000
15000
0
20
0.35

Soft Organic Clay
13
13
2
18
10
30
500
1000
2
9
0.45

4. Click the Save button to save the file for Tutorial 11.
5. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
6. Fill in and for Title
1 and Title 2 respectively in the Identification tab.
7. Click OK.
18.2

Model
Since this tutorial considers an installation of the pipeline in a trench the model trench should
be selected.
8. On the menu bar, click Project and then choose Model to open the Model window.
9. Select Construction in trench, and click OK.

Figure 18.2: Model window

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18.3

Geometry of the longitudinal cross section
This tutorial considers a layered soil sequence. The typical Dutch soil sequence of a soft
organic clay layer on top of a coarse sand layer will be considered. The organic clay layer is
compressible and exhibits a low permeability, while the sand layer is assumed incompressible
and exhibits a high permeability. The new soil layers should be specified in the geometry
window.
10. In the View Input window, switch to the Geometry tab to edit the existing soil layer sequence.
icon from the Edit sub-window to draw an additional top line of
11. Click the Add single line
a soil and position the straight line at Z = -5 m.
12. Click the Automatic regeneration of geometry on/off
icon from the Tools sub-window
so that the geometry as shown in Figure 18.3 appears. If the Automatic regeneration of
geometry icon is already selected, click on the Edit icon
to regenerate the geometry.
13. Click the Add pl-line(s)
icon from the Edit sub-window and position the level of the
artesian groundwater at coordinate Z = 8 m. The blue dashed line, which appears in the
longitudinal cross section, represents the second groundwater line (PL line 2). This second
groundwater line will be used in section 18.5.3 to specify the water pressure distribution in
the sand aquifer.

Figure 18.3: View Input window, Geometry tab

18.4

Soil layer properties
The properties of the soil layers in the layered soil sequence should now be specified.
14. Click Soil and select Materials on the menu bar to enter the soil data.
15. Add a new material by choosing the Add button
below the materials list on the left
side of the window. Enter the soil material name .
16. Enter the soil data given in Table 18.1.
17. Finish the input of soil data by clicking OK.

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Figure 18.4: Materials window

18.5

18.5.1

Phreatic Line
18. Click Geometry and select Phreatic Line on the menu bar to open the Phreatic Line window
(Figure 18.5) and select PL-line <1> as phreatic line for calculation of the groundwater
pressures.
19. Click OK.

Figure 18.5: Phreatic Line window

18.5.2

Layers
20. Click Geometry and select Layers on the menu bar to open the Layers window. Select the
Materials tab to assign the soil properties to the soil layers in the longitudinal cross section.
21. Assign the properties of the defined layer Soft Organic Clay to layer number 2 in the longitudinal cross section. The defined properties of Soft Organic Clay are assigned to layer
Number 2 by clicking the Assign icon
in between the left and the right column (Figure 18.6).

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Figure 18.6: Layers window, Materials tab

22. Click on the OK button to quit the window and return to the Geometry tab of the View Input
window to look at the change of layers name in the legend (Figure 18.7).

Figure 18.7: View Input window, Geometry tab

18.5.3

PL-Lines per Layer
23. Click Geometry and select Pl-lines per Layers on the menu bar to open the PL-lines per
Layer window to assign the defined PL–lines to the soil layers in the longitudinal cross
section. Those information’s are used for the calculation of the groundwater pressure
distribution.
24. The groundwater pressure at the top of the Soft Organic Clay layer should be calculated
based on the hydraulic head of PL–line 1, the phreatic line (Figure 18.5). Since the Coarse
Sand layer is an aquifer with an enhanced artesian groundwater pressure, the groundwater
pressure at the bottom of the clay layer should be calculated based on the hydraulic head
of PL–line 2. Of course the water pressure at the top and at the bottom of the coarse sand
layer should be calculated based on the hydraulic head of PL–line 2. This will result in the

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Pl-lines per layer window shown in Figure 18.8.

Figure 18.8: PL-lines per Layer window

25. Click OK to confirm.
26. The geometry can be tested by clicking Geometry on the menu bar and selecting Check
Geometry. If the geometry is entered properly, the message Geometry has been tested
and is OK appears.
27. Click OK to close this window.
18.6

Adding a waterway
A small waterway will now be drawn in the geometry.
28. Select the Geometry tab and select the Add poly line(s) button .
29. Draw a profile line as in Figure 18.9a. Remove points that are not required by clicking the
right mouse button and selecting the option Delete All Loose Lines.
30. Select the top line (between points 3 and 6 as shown in Figure 18.9b.
31. Click the Delete button . This should result in Figure 18.9c.

Figure 18.9: View Input window, Geometry tab (steps for drawing a waterway)

Now give the exact location of the waterway:
32. Check and enter the exact coordinates of the points by opening the Points window from
the Geometry menu.
33. Enter correct values for points 2, 3, 4 and 5 as shown in Figure 18.10.

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Figure 18.10: Points window

18.7

Calculation Verticals
In the subsequent table the verticals for the location of the calculations are given.
34. Open the Calculation Verticals window.
35. Enter <-70> and <130> for the First and Last L values and an Interval of <20>.
36. Click the Generate button.

Figure 18.11: Calculation Verticals window

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18.8

Boundaries Selection
To indicate the boundary compressible/uncompressible layers and impermeable/permeable
layers, the top of a specific layer is used. In this case it is evident that this is the top of the
coarse sand layer.
37. From the main menu click GeoObjects and select Boundaries Selection.
38. Select Top of layer <1> as both boundaries.
39. Click OK.

Figure 18.12: Boundaries Selection window

18.9

Trench configuration and pipe material
As the trench passes a small waterway, for practical reasons it has to subduct. An initial
distance of about 1.5 meter is chosen between trench and bottom waterway.
40. Click Pipe and select Pipeline Configuration from the menu bar to open the Pipeline Configuration window.
41. Enter the values as presented in Figure 18.13.
42. Click OK to accept the entries.

Figure 18.13: Pipeline Configuration window

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43. Now examine the trench trajectory in the Input (Figure 18.14) and Top View (Figure 18.15)
tabs of the View Input window.

Figure 18.14: View Input window, Input tab

Figure 18.15: View Input window, Top View tab

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18.10

Engineering Data
Next the engineering data is added. The trench is excavated in organic clay, and filled with
the excavated material, the fill is poorly compacted.
44. Click Pipe from the menu bar and select Engineering Data to open the Engineering Data
window.
45. Select as Type of fill and as Compaction of fill.
46. Click OK to confirm.

Figure 18.16: Engineering Data window

18.11

Results: Soil Mechanical Parameters
47. To start the calculations click Calculation and select Start on the menu bar or press the
function key F9.
48. Open the Report window from the Results menu to view the results of the Soil Mechanical
Parameters. The results can be found in paragraph 3.1 (Figure 18.17).
Since the fill of the trench is assigned the property “poorly compacted” a relatively high initial
soil load on the pipe is expected.

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Figure 18.17: Report window, Soil Mechanical Parameters section

The initial soil load Pv;a may be reduced by changing the fill property to “well compacted”
(see Equation 21.9 in section 21.4). Note that in reality this requires an extra compaction
treatment after installation of the pipe. In the software this can be adjusted in the Engineering
Data window under the Pipe menu.

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19 Tutorial 12: Trenching: uplift and heave
This tutorial is the continuation of tutorial 11 (chapter 18) and considers installation of a concrete sewer by means of trenching.
The objectives of the exercise are:

To evaluate the risk on heave of the bottom of the trench during installation;
To evaluate possible uplift of the empty pipe after installation.
The following modules are needed:

D-G EO P IPELINE Standard module (HDD)
Trenching module
This tutorial is presented in the files Tutorial-12a.dri, Tutorial-12b.dri and Tutorial-12c.dri.
19.1

Introduction to the case
During the excavation of a trench the groundwater conditions may play an important role. In
case a trench is excavated below the phreatic groundwater table or in case the hydraulic head
of an aquifer is relatively high, heave of the bottom of the trench is a serious risk. An other
risk, which may occur after excavation of the trench below the phreatic groundwater table, is
the uplift due to fill with a low density soil.
In this tutorial, the top layer consists of peat instead of organic clay. The peat exhibits a low
density. Besides a low density top layer, this tutorial considers a situation with a phreatic
groundwater table at the surface level.

Figure 19.1: Pipeline configuration for Tutorial 12

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Table 19.1: Layer properties (Tutorial 12)

Dry unit weight
Wet unit weight
Cohesion
Angle of internal friction
Undrained strength top
Undrained strength bottom
E modulus top
E modulus bottom
Adhesion
Friction angle
Poisson’s ratio

[kN/m ]
[kN/m3 ]
[kN/m2 ]
[◦ ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[kN/m2 ]
[◦ ]
[-]

Silty Sand
18
20
0
10
0
0
10000
15000
0
20
0.35

Peat
10.2
10.2
2
15
10
20
1000
1500
2
5
0.45

Soft Organic Clay
13
13
2
18
10
30
500
1000
2
9
0.45

This tutorial is based on continuation of the file used in Tutorial 11 (chapter 18).
1. Click File and select Open on the menu bar, and select Tutorial-11.
2. Click File and select Save as on the menu bar to open the Save As window and rename
the file into .
3. Click the Save button to save the file for Tutorial 12a.
4. On the menu bar, click Project and then choose Properties to open the Project Properties
window.
5. Fill in and for Title 1
and Title 2 respectively in the Identification tab.
19.2

Materials
The soil investigation showed presence of peat layers instead of organic clay. First, peat is
added to the material list.
6. Click Soil and select Materials on the menu bar to open the Materials window.
7. Select the existing Peat material in the left side of the window and enter the values as
given in Table 19.1.
8. Click OK.

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Figure 19.2: Materials window

Assign this material type to the top layer:
9. Click Geometry and select Layers on the menu bar.
10. To assign a material to a layer, select the Material tab. Select as well as layer
assign the soil to the layer (Figure 19.3).
number <2> and via the arrow button
11. Accept the input and return to the main window by clicking OK.

Figure 19.3: Layers window, Materials tab

19.3

Phreatic level
The phreatic line (groundwater table) is located at the surface level in this tutorial.
12. In the Geometry tab of the View Input window, select the Edit button
and click on the
PL line 1 in order to select the phreatic line by choosing Select PL Line 1.
13. Once the PL line 1 has been selected, drag it to the surface level by pressing and holding
down the left-hand mouse button while relocating the mouse cursor.

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14. Check and possibly correct the level of the line as shown in Figure 19.4.

Figure 19.4: PL-Line 1 window

Now the PL-line levels are defined at the correct levels, they have to be assigned to the correct
layers.
15. Open the PL-lines per Layer window from the Geometry menu.
16. Enter the PL–line numbers as given in Figure 19.5.

Figure 19.5: PL-lines per Layer window

19.4

Calculation Verticals
In the subsequent table the verticals for the location of the calculations are given.
17. Open the Calculation Verticals window.
18. Enter <-80> and <180> for the First and Last L values and an Interval of <20>.
19. Click the Generate button.

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Figure 19.6: Calculation Verticals window

20. Click OK and select the Input tab of the View Input window to view the new inputs (Figure 19.7).

Figure 19.7: View Input window, Input tab (Tutorial-12a)

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19.5

Factors
The required safety factors must be specified to evaluate the risk on bursting or heave of the
bottom of the trench.
21. Open the Factors window from the Defaults menu.
22. Enter <1.1> and <1.2> for the Safety factor uplift respectively Safety factor heave values.
23. Click OK.

Figure 19.8: Factors window

19.6

Results
Now the calculations can be performed.
24. To start the calculations click Calculation and select Start on the menu bar or press the
function key F9.

19.6.1

Uplift safety for trenching in Peat layer (Tutorial-12a)
To examine the risk of uplift the graph with the uplift safety factor can be opened
25. Open the Operation Parameters Plots window from the Results menu.

Figure 19.9: Operation Parameter Plots window, Safety uplift tab (Tutorial-12a)

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For a detailed examination, refer to paragraph 4.1.1 of the Report window (Figure 19.10). As
can be seen, the uplift safety of the trenched pipe is not OK as the calculated uplift factor
(0.12) is lower than the required uplift factor (1.1).

Figure 19.10: Report window, Uplift Factors section (Tutorial-12a)

19.6.2

Uplift safety for trenching in Soft Organic Clay layer (Tutorial-12b)
The trench fill should be modified. The low density of the peat causes uplift problems. The
effect of filling the trench with organic clay can easily be checked by changing the soil sequence.
26. Click File and select Save as on the menu bar to open the Save As window and rename
the file into .
27. Click the Save button to save the current project as Tutorial 12b.
28. Click Geometry and select Layers on the menu bar to open the Layers window. Select the
Materials tab (Figure 19.11) to assign the soil properties to the soil layers in the longitudinal
cross section.

Figure 19.11: Layers window, Materials tab (Tutorial-12b)

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29. Assign the properties of the defined layer Soft Organic Clay to layer Number 2 in the
longitudinal cross section. The defined properties of Soft Organic Clay are assigned to
layer Number 2 by clicking the Assign icon
in between the left and the right column.
30. Click on the OK button to quit the window and return to the Geometry tab of the View Input
window to look at the change of layers name in the legend.
31. To start the calculations again click Calculation and select Start on the menu bar or press
the function key F9.
32. Open the Operation Parameters Plots window from the Results menu.
33. Open the Report window from the Results menu.
34. Go to paragraph 4.1.1 of the report (Figure 19.12). As can be seen, the uplift safety of the
trenched pipe is still not OK as the calculated uplift factor (0.12) is lower than the required
uplift factor (1.1).

Figure 19.12: Report window, Uplift Factors section (Tutorial-12b)

19.6.3

Hydraulic Heave Safety
To examine the risk of heave of the trench bottom the graph with the heave safety factor can
be opened.
35. Select the Safety hydraulic heave tab of the Operation Parameters Plots window (Figure 19.13).

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Figure 19.13: Operation Parameter Plots window, Safety hydraulic heave tab (Tutorial12b)

Figure 19.14: Report window, Hydraulic heave of the trench bottom section (Tutorial-12b)

Note: In the report (Figure 19.14) the hydraulic heave safety of the trenched pipe is not OK for
all verticals, the calculated safety factors are lower than the required safety factor specified at
the default factors. Especially below the waterway the risk on bursting or heave of the bottom
of the trench is relatively high.
19.7

Lowering the hydraulic head (Tutorial-12c)
The problem of heave of the bottom of the trench can be solved by drainage of the subsequent
silty sand layer. By dewatering the silty sand layer, the hydraulic head can be lowered to the
required level. Lowering the level of the hydraulic head in the silty sand layers can be done as
follows:
36. Click File and select Save as on the menu bar to open the Save As window and rename

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37.
38.
39.
40.

the file into .
Click the Save button to save the current project as Tutorial 12c.
Return to the Geometry tab of the View Input window and select the button Add point(s)
to boundary / PL-line .
Click the four additional points on PL-line 2 as shown in Figure 19.15 (points 15 to 18).
Click the Geometry option from the menu bar and select the option Points. In the Points
window, enter the co-ordinates of points 15 to 18 (i.e. PL-line number 2 for the hydraulic
head in the sand layer) as given in Figure 19.16.

Figure 19.15: View Input window, Geometry tab (Tutorial 12c)

Figure 19.16: Points window (Tutorial 12c)

Now the results can be checked:
41. Start the calculations by clicking Start on the Calculation menu bar or by pressing the
function key F9.

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42. Open the Operation Parameter Plots window from the Results menu and select the Safety
hydraulic heave tab.
From the plots (Figure 19.17), it is clear that the drainage yields a higher calculated safety
factor for hydraulic heave safety.

Figure 19.17: Operation Parameter Plots windows, Safety hydraulic heave tab (Tutorial
12c)

43. Open the Report window to look at the calculated values (Figure 19.18): the minimum
calculated safety factor for Hydraulic Heave is 1.46 which is more than the required factor
of 1.20.

Figure 19.18: Report windows, Hydraulic heave of the trench bottom section (Tutorial
12c)

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20 Design of a pipeline
D-G EO P IPELINE can be used for designing a pipeline using four different techniques:

the HDD technique (section 20.1)
the micro-tunneling technique (section 20.2)
the trench technique (section 20.3)
20.1

Design of a pipeline crossing using the HDD technique
The horizontal directional drilling technique is used to install pipelines. A pipe is installed
from one point in a geometry with soil materials to another by means of horizontal directional
drilling. D-G EO P IPELINE can be used for the design of pipelines or the assessment of preliminary designs of pipelines constructed by means of horizontal directional drilling. Calculations
are based on the pipeline configuration, the drill pipe and borehole dimensions and the drilling
fluid data. D-G EO P IPELINE calculates the maximum allowable drilling fluid pressure and the
minimum drilling fluid pressure at user-specified calculation verticals.
The configuration of a proposed pipeline that has to cross an object is determined by:

the location of the entry and exit points (section 20.1.1)
the entry and exit angles (section 20.1.2)
the limitations of the object to be crossed, specified by the owner of the objects concerned (section 20.1.3)

the minimum value of curve radius (section 20.1.4)
the value of the combined bending radius (section 20.1.5)
20.1.1

Location of entry and exit points
The entry point is the location where the drilling rig is positioned during the pilot drilling. The
exit point is located at the other side of the object that has to be crossed. When the locations
of the entry and exit points are determined, it must be taken into account that a minimum
distance is required to the object in order to cross the object at a sufficient depth.

20.1.2

Inclination at the entry and exit points
The magnitude of the entry and exit angle is usually between 6◦ and 15◦ . The angle can be
larger for small drilling rigs. The greater the bending stiffness of the pipeline is, the smaller
the entry and exit angles are. Before starting to drill the curved parts of the drilling line, the
first 30 to 40 m (3 to 4 drill pipes) must be drilled in a straight line. The magnitude of the exit
angle influences the pull-back operation of the pipe through the borehole. The larger the exit
angle, the higher the pipeline has to be lifted in order to pull it into the borehole. A small exit
angle increases the risk that a blow-out will occur.

20.1.3

The limitations of the object to be crossed
The owner or manager of the object to be crossed may have certain requirements with regard
to the crossing depth of the pipeline. Such requirements can be related to the presence
of sheet piles or foundation piles. Another reason for special requirements can involve the
building plans of structures on piles. Such points are boundary conditions for preparing the
pipeline configuration.

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20.1.4

Determination of allowable curve radius
The borehole containing a pipeline is usually characterized by an upward and a downward
curve. Sometimes a horizontal or combined radius forms part of the drilling line. The smallest
possible radius of such a curve depends on the bending stiffness and the yield stress of the
pipeline or the drill pipes. For pipes with a relatively small bending stiffness, such as PE pipes,
the stiffness of the drill pipes is often the determining factor for the minimum radius of curved
sections in the drilling line.
Allowable curve radius for steel pipes
The design radius should be checked for strength:

R≥

γ × Eb Do
×
Reb
2

(20.1)

where:

Eb
Do
γ
Reb

is the modulus of elasticity of the pipe material, in kN/m2 ;
is the outer diameter of the pipe, in m;
is the partial safety factor for the bending moment;
is the minimum specified yield strength, in kN/m2 .

(For a pipeline with the following properties: Eb = 210000 N/mm2 ; Reb = 240 N/mm2 ; γ = 1.1,
about half the strength of the steel is available for bending stresses, while the remaining half
is used for stresses due to pulling force, internal pressure, etc. . . )
The design radius R for steel pipes should also be checked for soil reaction pressure due to
bending, according to article E.1.4 of NEN 3650-1:

R ≥ 1000 × Do
p
R ≥ C × Do × dn

for small pipe diameter (Do ≤ 0.4 m)

(20.2)

for large pipe diameter (Do > 0.4 m)

(20.3)

where C is a constant (without dimension) depending on the soil type as shown in Table 20.2.
Table 20.2: Values of constant C (according to table E.1 of NEN 3650-1)

Soil type
Dense packed sand
Moderate packed sand
Loose packed sand
Stiff Clay
Medium stiff clay
Soft clay and Peat

C [-]
8500
9400
10200
10500
11500
12500

In D-G EO P IPELINE, the soil type is a function of the cohesion and the friction angle of the soil,
as shown in Table 20.3.

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Table 20.3: Soil type as a function of the cohesion and the friction angle

ϕ [◦ ]
ϕ > 32.5
ϕ > 32.5
30 < ϕ ≤ 32.5
25 < ϕ ≤ 30
25 < ϕ ≤ 30
22.5 < ϕ ≤ 25
22.5 < ϕ ≤ 25
20 < ϕ ≤ 22.5
20 < ϕ ≤ 22.5
17 < ϕ ≤ 20
17 < ϕ ≤ 20
17 < ϕ ≤ 20
ϕ ≤ 17

Soil type
Dense sand
Medium dense sand
Medium dense sand
Loose sand
Stiff sandy clay
Stiff sandy clay
Clayey sand
Stiff clay
Medium stiff clay
Stiff clay
Medium stiff clay
Soft clay
Peat /organic clay

c [kN/m2 ]
c ≤ 0.5
c > 0.5

c≤1
c>1
c>5
c≤5
c > 10
c ≤ 10
c > 10
5 < c ≤ 10
c≤5

Constant C [-]
8500
9400
9400
10200
10500
10200
10500
10500
11500
10500
11500
12500
12500

In the case of a layered sub-soil, the highest C-value of a layer with a significant thickness is
normative. In the case of a sub-soil with an alternation of layers with relative small thicknesses,
a weighted interpolation can be performed to determine the C-value:

Cd =

n
X
i=1

Ci ×

di
dtotal

with dtotal =

n
X

(20.4)

i=1

where:

n
Ci
di
dtotal

is the total number of layers in the curve;
is the C-value of layer i;
is the thickness of layer i, in m;
is the total thickness of all layers in the curve, in m.

Allowable curve radius for polyethylene pipes
According to article 8.6.4 of NEN 3650-3 (NEN, 2012c), the minimal curve-radius for PE pipes
is equal to the bending factor as given in Table 20.5 times the diameter.
Table 20.5: Bending factor (acc. to table 6 of NEN 3650-3)

Diameter in mm
63 → 160
200 → 250
315 → 355
400 → 630
710 → 800

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50
75
100
100
125

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20.1.5

Determination of combined bending radius
In case the horizontal bending radius coincides with part of a vertical bending radius, a combined 3-dimensional bending radius is formed. For the design of the horizontal directional
drilling line, the pull back force and the strength calculation it is necessary to determine the
value of the 3-dimensional bending radius. This value can be determined as follows:

s
Rcombi =

Rh2 × Rv2
Rh2 + Rv2

(20.5)

where:

Rcombi is the combined bending radius, in m;
Rh
is the horizontal bending radius, in m;
Rv
is the vertical bending radius, in m.
20.2

Design of a pipeline crossing using the micro tunneling technique
The micro tunneling technique is often used for installation of pipelines and small tunnels in
densely populated areas. Micro tunneling usually starts horizontal at a certain level below
the surface in a so-called launch shaft. The pipe segments included in the micro tunneling
machine are placed behind the tunneling machine and pushed in the direction of the reception
shaft by means of a jacking frame (Figure 20.1).
The so-called thrust force which has to be provided by the jacking frame is an important
parameter in the design of tunnels and pipelines installed by means of micro tunneling. Of
course the jacking frame must be able to produce this force.

Figure 20.1: Launch and reception shafts of the micro tunneling machine

20.3

Design of a pipeline using a trench
Very often, under normal circumstances, pipelines are installed in an excavated trench. In
the not very densely populated areas such as agricultural areas and not developed areas, the
slopes of the trenches can often be excavated under.
The main risk associated with trenching is instability of the slopes of the trench. This risk is can
not be considered in D-G EO P IPELINE. Use of other computer programs such as D-G EO S TABILITY
is recommended to evaluate this risk.

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21 Calculation of soil mechanical data
This section includes background information on the calculation of:

neutral vertical stress (section 21.1)
passive vertical stress (section 21.2)
reduced vertical stress (section 21.3)
actual vertical stress (section 21.4)
neutral horizontal stress (section 21.5)
vertical modulus of subgrade reaction (section 21.6)
horizontal modulus of subgrade reaction (section 21.7)
ultimate vertical bearing capacity (section 21.8)
ultimate horizontal bearing capacity (section 21.9)
vertical displacement (section 21.10)
maximal axial friction and friction displacement (section 21.11)
displacement at maximal friction (section 21.12)
global determination of the soil type (section 21.13)
traffic load (section 21.14)

If the definition of some parameters in the equations of this chapter is missing, refer to section 1.7.
21.1

Neutral vertical stress

Figure 21.1: Schematic diagram for calculation of the neutral vertical stress

According to article C.4.2.2 of NEN 3650-1 (NEN, 2012a), the neutral vertical stress qn is
defined as (Figure 21.1):

qn = σv0 (H) + (0.5 − π/8) × γ 0 × Do

(21.1)

where:

σv0 (H)
H
γ’

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is the vertical effective stress at depth H , in kN/m2 :
σv0 (H) = γunsat × H1 + (γsat − γw ) × H2 (see Figure 21.2 for the definition of
H1 and H2 ).
is the soil cover above the top of the pipe, in m (see Figure 21.2).
is the effective unit weight of the soil, in kN/m3 : γ 0 = γunsat above the phreatic
line and γ 0 = γsat − γw below the phreatic line.

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Figure 21.2: Schematic diagram for the definition of parameters H1 , H2 , γunsat and γsat
(Figure C.5 of NEN 3650-1)

21.2

Passive vertical stress
According to article C.4.2.4.2 of NEN 3650-1, the passive vertical stress qp is defined as:

H
qp = qn × 1 + 0.3
≤ p0max
Do

(21.2)

with:

p0max = (p0f + c × cot ϕ) ×

0.5 × Do
0.5 × Do + H

− sin ϕ
# 1+sin
ϕ

2
+q

− c × cot ϕ

(21.3)

where:

p0max
p0f
q
σ0 ’
σv,h ’
c, ϕ, G

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is the maximum passive vertical stress, in kN/m2 ;
is σ00 (1 + sin ϕ) + c × cos ϕ, in kN/m2 ;
is (σ00 × sin ϕ + c × cos ϕ) /G, in kN/m2 ;
is the effective isotrope stress, in kN/m2 : σ00 = (σv0 + σh )/2;
is the vertical respectively horizontal effective stress;
are the soil parameters at the pipe center.

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21.3

Reduced neutral vertical stress
In case a drilling technique is used for the installation of the pipeline, the vertical soil load is
reduced due to arching. A pipeline installed using the horizontal directional drilling technique
is loaded by a strongly reduced soil loads due to arching. For micro tunneling the effect of
arching on the soil load is calculated by D-G EO P IPELINE as well. Due to the relative small
borehole arching is not completely developed. The relatively small available strain yields
incomplete mobilization of the shear strength. The soil load in case of micro tunneling should
therefore be calculated using half the value of the angle of internal friction.

Figure 21.3: The mobilization of the angle of internal friction in the development of the
arching mechanism

21.3.1

Reduced neutral vertical stress in compressible soil layers
According to article C.4.8.3 of NEN 3650-1 (NEN, 2012a), in compressible soil layers (i.e. clay
and peat), the reduced neutral vertical stress qn,r is defined as:

qn,r =

h × γ 0 − Fr /2B1 if z > 8B1
qn
if z ≤ 8B1

(21.4)

with:

Fr =

0.9 Fmax
1+

B1×(3H−2h)×α

2C×H δd + 2B

Fmax
1 ×kv;drill fluid

(21.5)

Fmax = 2B1 × (h × γ 0 − qn,r1 )

B1 × γ 0 − Bc1
−K × tan ϕ × h
qn,r1 =
× 1 − exp
K × tan ϕ
B1

(21.6)
(21.7)

where:

B1
ϕb
h
c, ϕ , γ ’
Fr
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is the half width of the covered ground column, in m:
B1 = 0.5Do + Do × tan (45◦ − ϕb /2 ) ≥ R;
is the average friction angle over the height of the borehole, in degree;
is the soil cover above the borehole, in m (see Figure 21.4);
are the average soil parameters between the surface and the pipe center;
is the permanent friction due to arching effect, in kN/m2 :

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is the maximal adhesion, in kN/m2 ;
is the reduced neutral vertical stress on the pipe, in kN/m2 ;
is the thickness of the compressible layers, in m (see Figure 21.4);
is a dimensionless factor: α = ln(h/href ) with href = 1 m;

Fmax
qn,r1
H
α

Figure 21.4: Definitions of H , h and hh

21.3.2

Reduced neutral vertical stress in non-compressible soil layers
According to articles C.4.8.3 and C.4.8.4 of NEN 3650-1 (NEN, 2012a), in incompressible soil
layers (i.e. sand) situated below compressible soil layers, the reduced neutral vertical stress
qn,r is defined as (if h > 8B1 ):

qn,r

−K · tan ϕ · hp
−K × tan ϕ × hp
B1 × γ 0
=
1 − exp
+ σc exp
K × tan ϕ
B1
B1
(21.8)

where:

γ’
hp
ϕ
σc

is the average effective unit weight of the soil between the compressibility border
and the pipe center, in kN/m3 ;
is the soil cover above the borehole in the incompressible layers (see Figure 21.5),
in m;
is the average friction angle between the compressibility border and the pipe center,
in degrees;
is the vertical effective stress at the compressibility border, in kN/m2 (see Figure 21.5).

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Figure 21.5: Schematic diagram of H and hp

If hp < 8B1 , Equation 21.8 is not applicable for the determination of qn,r . In such case, the
following applies:
1) 0 < hp < 2B1 :
2) 2B1 ≤ hp ≤ 4B1 :

qn,r is constant and equal to qn,r -border, see section 21.3.1;
interpolation between qn,r -border and qn,r -incompressible for
hp = 4B1 ;
qn,r -incompressible as a function of hp .

3) hp ≥ 4B1 :

If qn,r -incompressible (hp = 4B1 ) is larger than qn,r -border, then 1) is prescribed and 2) is
applicable for 0 < hp < 4B1 .
21.4

Initial vertical stress
According to article C.4.2.3 of NEN 3650-1 (NEN, 2012a), the initial vertical stress qk (also
called actual vertical stress) for construction in trench is defined as:

qk = qn + kv,tot × µ × Do ≤ qp

(21.9)

with:

kv,tot
kv,pipe

1
kv,top

kv,pipe kv,bottom
EIw
=
ky × Do × Dg3

(21.10)
(21.11)

where:

qn
qp
kv,tot

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is the neutral vertical stress of the soil, in kN/m2 , see Equation 21.1;
is the passive vertical stress of the soil, in kN/m2 , see Equation 21.2;
is the vertical modulus of subgrade reaction upward, in kN/m3 , see Equation 21.15;
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kv,bottom is the minimum vertical modulus of subgrade reaction downward, in kN/m3 , calculated according to section 21.6.2;
is the vertical modulus of subgrade reaction of the pipe, in kN/m3 ;
is the percentage of compaction depending on the type of fill and type of compaction as shown in Table 21.7.

kv,pipe
µ

Table 21.7: Values of parameter µ according to NEN 3650-1

Compaction
Poorly
Well

21.5
21.5.1

Soft soil
0.20
0.10

Type of fill
Stiff clay
0.15
0.075

Sand
0.075
0.02

Neutral horizontal stress
Pipelines installed using the HDD technique
According to article C.4.8.6 of NEN 3650-1, the neutral reduced horizontal soil load qh,r for a
pipeline installed using the horizontal drilling technique can be calculated using the following
equation:

qh,r = qn,r × (1 − sin ϕdf )

(21.12)

where:
is the reduced neutral vertical stress of the soil, in kN/m2 , as calculated in section 21.3;
is the angle of internal friction of the drilling fluid, as defined in the Engineering
Data window (section 4.6.3.1). The default value is 15◦ .

qn,r
ϕdf

21.5.2

Pipelines installed in a trench or using micro tunneling
The neutral horizontal soil load qh,n for a pipeline installed in a trench or using the micro
tunneling technique can be calculated using the following equation:

qh,n = qn × (1 − sin ϕb )

(21.13)

where:

qn
ϕb

is the neutral vertical stress of the soil, in kN/m2 , as calculated in Equation 21.1 in
section 21.1;
is the average angle of internal friction of the soil over the height of the borehole.

In micro tunneling the space in between the pipeline or tunnel is usually relatively small,
moreover the space in between the bore hole wall and the pipeline or tunnel is often filled with
grout after installation.

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21.6

Vertical modulus of subgrade reaction
Due to the soil-pipe interaction, induced by either the pipe or the soil, soil deformations and
pipe displacement will occur. The deformations lead to increase or decrease of the soil load on
the pipe. This soil reaction behavior is modeled by using a spring model. By locating springs
around the pipe, the displacement and related stress changes can be calculated (Figure 21.6).
The increase or decrease of the soil reaction stress is usually calculated by linear or bi-linear
springs. The stiffness of the spring is expressed as a modulus of subgrade reaction.

Figure 21.6: Pipe soil interaction modeled by springs

Since the soil-pipe interaction is influenced by the installation method, different calculation
methods to determine the moduli of subgrade reaction exist:

For installation using a drilling technique (HDD or micro tunneling), refer to section 21.6.1;
For Installation in a trench, refer to section 21.6.2;
21.6.1

Pipelines installed using a drilling technique
According to article C.4.3.3 c) of NEN 3650-1, the stiffness of the spring below (kv,bottom ) and
above the pipe (kv,top ) is:

kv =

fE × E
√
m × (1 − ν 2 ) × A

(21.14)

with:

52.31 + `/b
51.90 + 3.596 × `/b
` = π/λ
r
Do
λ = 4 kv × fkv ×
4 Eb × Ib
m=

where:

E, ν
A
b
`
λ
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are the average parameters of the soil along a distance of 5 Do above the top of
the pipeline for kv,top and below the bottom of the pipeline for kv,bottom ;
is ` × b = support area, in m2 ;
is the minimum support width, in m: b = Do ;
is the minimum support length, in m;
is the characteristic stiffness pipeline-soil, in m−1 ;
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is the moment of inertia of the pipeline, in m4 : Ib =
is the shape coefficient, depending on `/b.

Ib
m
21.6.2

π
64

Do4 − (Do − 2dn )4

Pipelines installed in a trench
Vertical modulus of subgrade reaction upward
According to article C.4.3.2 of NEN 3650-1, the vertical modulus of subgrade reaction upward
are:

qp − qn
zmax
qp
kv,top,max =
zmax
v,top

(21.15)
(21.16)

with:

zmax =

0.25 × Do
q
E 1.5 × DHo

for clay and peat

(21.17)

zmax =

0.20 × Do
q
E 0.5 × DHo

for sand

(21.18)

where:

qp
qn
zmax
E
H

is the passive vertical soil load, see Equation 21.2;
is the neutral vertical soil load, see Equation 21.1;
is the maximum displacement, in m;
is the average Young’s modulus of the soil along a distance of 5 Do above the top
of the pipeline, in MPa;
is the soil cover above the top of the pipe, in m.

Vertical modulus of subgrade reaction downward
The vertical modulus of subgrade reaction downward is characterized by a bi-linear spring.
kv,1 is the modulus of subgrade reaction in between 0 and 2/3 of the vertical bearing capacity,
while kv,2 is the modulus of subgrade reaction in between 2/3 of the vertical bearing capacity
and the vertical bearing capacity.
For clay and peat, the modules of subgrade reaction downward are:

Pwe
Do
Pwe
= 0.04 × cu ×
Do

kv,1 = 0.25 × cu ×

(21.19)

kv,2

(21.20)

For sand, the modules of subgrade reaction downward are:

Pwe
Do
Pwe
= 0.1 × E ×
Do

kv,1 = 0.5 × E ×

(21.21)

kv,2

(21.22)

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Calculation of soil mechanical data

where cu and E (in kN/m2 respectively MN/m2 ) are the average parameters of the soil along
a distance of 5 Do below the bottom of the pipeline and Pwe is the vertical bearing capacity
determined according to section 21.8.
If cu is nil, a fictive undrained cohesion is used by the program:

cu,fictive =
21.7
21.7.1

1
(1 + K0 ) × σh0 × sin ϕ + c × cos ϕ
2

(21.23)

Horizontal modulus of subgrade reaction
Pipelines installed using a drilling technique
The horizontal modulus of subgrade reaction is:

kh = 0.7 kv,bottom

(21.24)

where kv,bottom is the vertical modulus of subgrade reaction at the bottom of the pipe as determined in Equation 21.14.
21.7.2

Pipelines installed in a trench
According to article C.4.3.4.1 of NEN 3650-1, the horizontal modulus of subgrade reaction
upward is:

kh =

qhe
(1 − 0.3 × B)
×
ymax
A

(21.25)

where:

qhe
ymax
A
B
21.8

is the ultimate horizontal bearing capacity, see Equation
21.29;
h

is the maximal displacement, in m: ymax = Do × 0.05 + 0.03 ×

Z
Do

i
+ 0.5

is a constant (A = 0.145);
is a constant (B = 0.855).

Ultimate vertical bearing capacity
According to article C.4.4.2 of NEN 3650-1 (NEN, 2012a), the ultimate vertical bearing capacity is:

Pwe = 0.95 [0.5 γ 0 B Nγ Sγ dγ + Sq Nq dq (qn + c × cot ϕ) − c × cot ϕ]
(21.26)
where:

c, ϕ, γ ’
B
Z
H
L
Nγ
sγ
dγ
Deltares

are the average soil parameters along the sliding plane;
is the width of the foundation element, in m (for pipeline: B = Do );
is the depth until the pipe, in m: Z = H + Do /2;
is the soil cover above the pipe, in m;
is the length of the foundation element, in m: L = 10 B ;
is the bearing capacity factor for the effect of the effective weight of the soil under
the foundation surface: Nγ = 1.5 × (Nq − 1) × tan ϕ
is the shape factor for the effect of effective weight of the soil under the foundation
surface: sγ = 1 − 0.4B/L;
is the depth factor for the effect of the effective weight (dγ = 1);

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is the bearing capacity factor for the
effect of the soil cover:
ϕ
π×tan ϕ
2 π
Nq = exp
× tan 4 + 2 ;
is the shape factor for the effect of soil cover: sq = 1 + sin ×B/L;
is the depth factor for the effect of the soil cover:
dq = 1 + 2 tan ϕ (1 − sin ϕ)2 arctan (Z/B).

sq
dq

If ϕ = 0, the ultimate vertical bearing capacity is:

Pwe = 0.95 [σv0 + c (π + 2) × (1 + sc + dc )]

(21.27)

where:

sc
dc
21.9
21.9.1

is the shape factor for the effect of cohesion: sc = 0.2B/L = 0.02;
is the depth factor for the effect of cohesion: dc = 0.4 arctan (Z/B).

Ultimate horizontal bearing capacity
Pipelines installed using the HDD technique
The horizontal bearing capacity qhe is of equal magnitude as the maximum vertical passive
soil load p0max (see Equation 21.3) and is therefore defined as:

qhe = p0max = (p0f + c × cot ϕ) ×

0.5 Do
0.5 Do + H

− sin ϕ
# 1+sin
ϕ

2
+q

− c × cot ϕ
(21.28)

Refer to section 21.2 for the definition of the parameters.
Similar to the determination of the maximum vertical passive soil load, for shallow depth of the
pipeline (H < 5Do ) the soil load should be calculated according the formula for the horizontal
bearing capacity for trench or micro tunneling.
21.9.2

Pipelines installed in a trench or using micro tunneling
According to article C.4.4.3a, the horizontal bearing capacity qhe of a pipeline in a trench or
using the micro tunneling technique is calculated as follows:

qhe = Kq × σv0 + 0.7 × α × Kc × c

(21.29)

where:

Kq
Kc
σv0
α

is the load coefficient according to Brinch Hansen, see Figure 21.7 and Equation 21.30;
is the load coefficient according to Brinch Hansen, see Figure 21.7 and Equation 21.31;
is the effective vertical stress at the pipe center, in kN/m2 ;
is a coefficient: α = 0.6 for trench and α = 1 for micro tunneling.

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Calculation of soil mechanical data

Figure 21.7: Values Kq and Kc according to Brinch Hansen (Figure C.14 of the
NEN 3650-1)

The angle of internal friction ϕ and the cohesion c for the calculation of the load coefficients
Kq and Kc is determined for the soil layers 2.5 Do above and 2.5 Do below the axis of the
pipeline. The minimum value is used. According to Brinch Hansen (Brinch Hansen, 1970),
the load coefficients are:

Kq =
Kc =

Kq0 + Kq∞ × αq ×
1 + αq ×

D
B

(21.30)

D
B

Kc0 + Kc∞ × αc ×
1 + αc × D
B

D
B

(21.31)

where:

ϕ
Kq = exp
+ ϕ × tan ϕ × cos ϕ × tan
+
4 2
h2 π

i
π ϕ
− exp − + ϕ × tan ϕ × cos ϕ × tan
−
n
h π 2
i
π 4 ϕ 2
o
Kc0 = exp
+ ϕ × tan ϕ × cos ϕ × tan
+
− 1 × cot ϕ
2
4
2
Kq∞ = Kc∞ × K0 × tan ϕ
Kc∞ = Nc × d∞
c
∞
dc = 1.58 + 4.09 × tan4 ϕ
h
π ϕ
i
Nc = exp (π × tan ϕ) × tan2
+
− 1 × cot ϕ
4
2
K0 = 1 − sin ϕ
Kq0
K0 × sin ϕ

αq = ∞
×
0
Kq − Kq
sin π4 + ϕ2
π ϕ
Kc0
αc = ∞
× 2 sin
+
Kc − Kc0
4
2
0

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21.10

Vertical displacement
The vertical displacement of the soil layers below the pipeline due to an increased load on
these layers can be calculated using the Isotache method or the Koppejan method. In addition to the calculated vertical displacement by D-G EO P IPELINE, a given value for vertical
displacement can be entered manually (see section 4.4.2).

21.10.1

Isotache model
Creep Isotaches are lines of equal rate (speed, velocity) of secular (visco-plastic) strain εH
s
in a plot of (natural) strain versus (natural) logarithm of vertical effective stress. These are
displayed in the Figure 21.8.

Figure 21.8: Creep Isotache pattern

The Isotaches are all parallel with slope b−a. The Isotache a parameter determines the direct
(elastic) strain component εH
d . The b and c parameters determine the secular (visco-plastic)
H
creep component εs .

dεHs
d ln σ 0
dεHs
c=−
d ln (ε̇Hs )
dεHd
a=
d ln σ 0
H
ε = εHs + εHd

b−a=

(21.32)
(21.33)
(21.34)
(21.35)

The reference Isotache starts at pre-consolidation stress σref = σp and is characterized by a
reference creep strain rate ε̇H
s.ref .
The secular creep rate is given by:


ε̇Hs = ε̇Hs.ref exp 

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(b − a) ln

0
σ
σp

− εHs




(21.36)

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Calculation of soil mechanical data

It can be shown that the secular creep rate is related to a so-called intrinsic time τ , which is
related to the common time t by a time shift tshift .

ε̇Hs =

c
τ

τ = t − tshift

with

(21.37)

This time shift in fact represents the creep history of the soil.
The total rate of strain is the sum of the elastic and secular rates:

ε̇H = ε̇Hs + ε̇Hd

(21.38)

Time integration of Equation 21.38 finally yields Equation 21.39.

ε = a ln

σ0
σ0

+ c ln 1 +
0

σ0
σp

b−a
c

dτ
τ0

(21.39)

The reference time τ0 is set by default to 1 day.

τ0 = 1 day

(21.40)

During a constant stress period after virgin loading, Equation 21.39 simplifies to:

εH = a ln

σp
σ0
τ
+ b ln
+ c ln
σ0
σp
τ0

(21.41)

This equation applies to the creep tail when σ ’ has become constant, and this is the familiar
relation for one-dimensional creep, with strain depending on logarithm of time.
Here, however, apart from using natural strain, the time to use is the intrinsic time τ . This
removes the age-old difficulty of defining the origin of time to use in the compression law, e.g.
years A.D. (Buisman: dykes of Marken island), time after loading, time after last loading stage,
etc.
Figure 21.9 illustrates the effect of the tshift parameter (denoted by tr ) on the creep tail.

Figure 21.9: Influence of the tshift = tr parameter on the creep tail

While H – log t plots can be either steepening or flattening, the H – log τ plot is linear.
Steepening occurs for relatively small load increments, and is due to changing the origin of
time to the start of the new increment. Flattening occurs for relatively large load increments.
The linear relationship with intrinsic time therefore allows a more accurately identification and
interpretation of the creep tail.

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21.10.2

Koppejan model

Figure 21.10: Koppejan settlement

Four different situations can be distinguished for Koppejan:

If the vertical effective stress is smaller than the pre-consolidation pressure, the primary
settlement can be calculated from:

∆hprim
1
=
ln
h0
Cp

σ0
σ0

, σ0 < σ 0 < σp

(21.42)

If the vertical effective stress is larger than the pre-consolidation pressure, the primary
settlement can be calculated from:

∆hprim
1
=
ln
h0
Cp

σp
σ0

1
+ 0 ln
Cp

σ0
σ0

, σ0 < σp < σ 0

(21.43)

If vertical effective stress is smaller than the pre-consolidation pressure, the secondary
settlement for one loading can be calculated from:

1
∆hsec
=
log
h0
Cs

0
t
σ
ln
, σ0 < σ 0 < σp
t0
σ0

(21.44)

If the vertical stress is larger than the pre-consolidation pressure, the secondary settlement for one loading can be calculated using Equation 21.45:

∆hsec
1
=
log
h0
Cs

0
t
σp
1
t
σ
ln
+ 0 log
ln
, σ0 < σp < σ 0
t0
σ0
Cs
t0
σp
(21.45)

where:

Cp
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is the primary compression coefficient below pre-consolidation pressure;
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Calculation of soil mechanical data

Cp ’
Cs
Cs ’
∆hprim
h0
σ0
σp
∆hsec
t
t0
21.11

is the primary compression coefficient above pre-consolidation pressure;
is the secondary compression coefficient below pre-consolidation pressure;
is the secondary compression coefficient above pre-consolidation pressure;
is the primary settlement contribution of a layer, in m;
is the initial layer thickness, in m;
is the initial vertical effective stress, in kN/m2 ;
is the pre-consolidation pressure, in kN/m2 ;
is the secondary settlement contribution of a layer, in m;
is the time, in days;
is the reference time, in days.

Maximal axial friction
The friction between the pipe wall and the surrounding soil depends on the relative displacement between the pipe wall and the soil. When the relative displacement between the soil
and the pipe reaches a maximal value, the friction does not increase anymore. The friction
depends on:

21.11.1

The stresses around the pipe
The adhesion between the soil and the pipe wall
The roughness of the pipe wall
The angle of friction of the soil

Pipelines installed using the HDD technique
The maximal axial friction along the pipeline can be put in the Engineering Data window
(section 4.6.3) as parameter f2 (friction between pipe – drilling fluid). The conditions directly
after the installation are considered as critical.

21.11.2

Pipelines installed in a trench or using micro tunneling

Figure 21.11: Schematization of the forces acting on the pipe

The following forces are acting on the pipe (Figure 21.11):

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a) Uplift force:

quplift =

π
× Do2 × γdf
4

(21.46)

b) Weight of the pipeline:

qpipe =

π
× Do2 − Di2 × γb
4

(21.47)

c) Weight of the filling (water):

qfilling =

π
× Di2 × γw × Pw
4

(21.48)

d) Stress at the top of the pipe:

qtop =

max [qn ; min (−qeff ; qp )] for trenching
max [qn,r ; min (−qeff ; qp )] for micro tunneling

(21.49)

e) Stress at the bottom of the pipe:

qbottom =

max (qn + qeff ; Pwe ) for trenching
max (qn,r + qeff ; Pwe ) for micro tunneling

(21.50)

The effective weight of the pipeline is defined as:

qeff = qpipe + qfilling − quplift

(21.51)

where:

qn
qp
qn,r
Pwe

is the neutral vertical stress, see Equation 21.1 in section 21.1;
is the passive vertical stress, see Equation 21.2 in section 21.2;
is the reduced neutral vertical stress, see section 21.3;
is the vertical bearing capacity, see Equation 21.26 in section 21.8.

The maximal axial friction along the pipeline is defined as follows:

W = Wtop + Wbottom + 2Whor

(21.52)

with:

Wt =

Wb =

π
4
π
4
π
4
π
4

Whor =

Do (qt × tan δt + 0.6 × at )
Do (qt × tan δlub fluid + alub fluid )
Do (qb × tan δb + 0.6 × ab )
Do (qb × tan δlub fluid + alub fluid )
π
4
π
4

for trenching
for micro tunneling
for trenching
for micro tunneling

Do (K0 × σv0 × tan δm + 0.6 × am )
Do (Ka × σv0 × tan δlub fluid + alub fluid )

for trenching
for micro tunneling

where:

W
at , ab , am

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is the maximal friction, in kN/m;
are the adhesion’s of the soil at the top, respectively bottom and middle of the
pipe, in kN/m2 ;
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Calculation of soil mechanical data

δt , δb , δm
alub fluid
δlub fluid
K0
Ka
ϕ
σv ’
21.12
21.12.1

are the delta friction angles of the soil at the top, respectively bottom and
middle of the pipe, in radians. For sand, δ can be approximated by 2/3 ϕ,
while in clay and peat the value of the friction angle can be neglected (δ = 0).
is the adhesion of the lubrification fluid, in kN/m2 , as defined in the Engineering Data window (section 4.6.3.2);
is the delta lubrification fluid, in radians, as defined in the Engineering Data
window (section 4.6.3.2);
is the neutral earth pressure ratio: K0 = 1 − sin ϕ;
is the active earth pressure ratio: Ka =

cos ϕ
1+sin ϕ

;

is the friction angle of the soil at the middle of the pipe, in radians;
is the effective vertical stress at the middle of the pipe, in kN/m2 .

Displacement at maximal friction
Pipelines installed using the HDD technique
The displacement necessary to develop the maximal axial friction along the pipeline is estimated between 6 and 9 mm. D-G EO P IPELINE uses an average value of 7.5 mm.

21.12.2

Pipelines installed in a trench or using micro tunneling
The displacement necessary to develop the maximal axial friction along the pipeline is determined using Table 21.19.

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Table 21.19: Friction displacement

Soil type

[◦ ]

ϕ > 32.5
30 < ϕ ≤ 32.5
ϕ > 30
25 < ϕ ≤ 30
25 ≤ ϕ ≤ 30
22.5 < ϕ < 25
ϕ ≥ 22.5
ϕ > 17
20 < ϕ ≤ 22.5
17 ≤ ϕ ≤ 20
17 ≤ ϕ ≤ 20
ϕ < 17

Dense sand
Medium dense sand
Stiff clay
Loose sand
Stiff sandy clay
Clayey sand
Stiff sandy clay
Stiff clay
Medium stiff clay
Medium stiff clay
Soft clay
Peat /organic clay
21.13

c
[kN/m2 ]
c ≤ 0.5
c ≤ 0.5
c > 0.5
c<1
c≥1
c<5
c≥5
c ≥ 10

Friction displacement
[mm]
1-3
3-5
2-4
5-8
4-6
5-8
2-4
2-4
4-6
4-6
6-10
10-15

c≥5
c<5

Global determination of the soil type
The global soil type in which the pipeline is installed is used for the determination of safety
factors which are required for a pipe stress analysis. The classification of global soil types
given in Table 21.20 is applied in D-G EO P IPELINE.
Table 21.20: Classification of the soil type

Global soil type

ϕ
[◦ ]

Sand
Sand
Clay
Sand
Clay
Sand
Clay
Clay
Clay
Clay
Clay
Peat
21.14

ϕ > 32.5
30 < ϕ ≤ 32.5
ϕ > 30
25 < ϕ ≤ 30
25 ≤ ϕ ≤ 30
22.5 < ϕ < 25
ϕ ≥ 22.5
ϕ > 17
20 < ϕ ≤ 22.5
17 ≤ ϕ ≤ 20
17 ≤ ϕ ≤ 20
ϕ < 17

c
[kN/m2 ]
c ≤ 0.5
c ≤ 0.5
c > 0.5
c<1
c≥1
c<5
c≥5
c ≥ 10
c≥5
c<5

Traffic load
According to C.5.1 of NEN 3650-1 (NEN, 2012a) two load models are considered, depending
on the type of road:

For dual carriageways and regional roads, ’Load Model 3’ (i.e. Graph I) according to
EN NEN-1991-2 (this concerns special transports) is assumed;

For other roads, the ’Fatigue Load Model 2, Lorry 4’ (i.e. Graph II) is assumed according
to EN NEN-1991-2 (this load model covers the ’set of frequent lorries’ wich can occur
on European roads, such as described in EN NEN-1991-2, with exception of the special
transports).

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Figure 21.12: Traffic load as a function of the depth and the pipe diameter, for both load
models, according to NEN 3650-1

For both load models (Graph I and Graph II), the spreading of the traffic load qv along the depth
is given in Figure 21.12 for four pipe diameters: 200, 600, 1000 and 1600 mm. Intermediary
diameters are linearly interpolated. D-G EO P IPELINE uses the following formulas to calculate
qv as a function of the depth Z , derived from Figure 21.12:

For Graph I:

For 200 mm: qv = 53.988 × Z −1.058
For 600 mm: qv = 51.403 × Z −1.016
For 1000 mm: qv = 46.522 × Z −0.94
For 1600 mm: qv = 39.448 × Z −0.804
For Graph II:
For 200 mm: qv = 31.716 × Z −1.457
For 600 mm: qv = 29.501 × Z −1.4
For 1000 mm: qv = 26.776 × Z −1.324
For 1600 mm: qv = 21.963 × Z −1.172

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22 Drilling fluid pressures calculation
This section includes background information on the calculation of the following drilling fluid
pressures:

Minimum required drilling fluid pressure (section 22.1)
Maximum allowable drilling fluid pressure (section 22.2)
22.1

Minimum required drilling fluid pressure
Drilling fluid consists of a mixture of water and bentonite or may have another composition
(polymers) . This mixture has some special properties. The flow behavior of the fluid is
an important characteristic for the development of drilling fluid pressure during the different
drilling stages. Various types of drilling fluids exist. Generally, the flow behavior of drilling fluid
can be described with the Bingham model. The Bingham model describes the fluid by means
of a viscosity term and a threshold term from which flow is initialized. The threshold is called
the yield point.
D-G EO P IPELINE calculates the required minimum fluid pressure at predefined locations. In
these calculations, the flow properties of the drilling fluid (density, viscosity and yield point)
play an important role.
During all stages of the drilling process, a pipe is present in the borehole, drill pipe or product
pipe. The return flow of drilling fluid with cuttings occurs in the annulus between the borehole
wall and the pipe. The required fluid pressure to initiate flow depends on the width of the
annulus (radius borehole minus radius drill pipe), the properties of the drilling fluid and the
required annular fluid flow rate.
To obtain the minimum required pressure pmud;min , the following pressure values must be
calculated and added up:

pmud;min = p1 + p2

(22.1)

where:
is the static pressure of the drilling fluid column, in kN/m2 .
is the excess pressure necessary to maintain the annular flow of drilling fluid with
cuttings in the borehole, in kN/m2 .

p1
p2

22.1.1

Static pressure of the drilling fluid column p1
As the drilling head is at a lower level than the exit point of the drilling fluid, a pressure difference has to be overcome which is equal to the difference in height times the unit weight of the
drilling fluid:

p1 = γdf × (Zexit − Z)

(22.2)

where:

γdf

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is the unit weight of the drilling fluid, in kN/m3 ;

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Zexit

is the vertical co-ordinate of the exit point of the drilling fluid, in m, depending on
the direction of the drilling:
If the drilling is from left to right, then the exit point of the drilling fluid is the
left point: Zexit = Zleft ;
If the drilling is from right to left, then the exit point of the drilling fluid is the
right point: Zexit = Zright
Refer to section 4.6.1.1 for the definitions of Zleft and Zright .
is the vertical co-ordinate at pipe center, in m.

Z
22.1.2

Excess pressure to maintain flow of drilling fluid p2
To initiate the flow of drilling fluid, a specific shear resistance in the fluid must be overcome.
The drilling fluid flows through an annulus. The required excess fluid pressure depends on
the width of the annulus (difference between borehole and drill pipe or product pipe radius),
the flow properties of the drilling fluid, and the required flow rate.
The required excess pressure necessary to maintain the annular flow of drilling fluid with
cuttings in the borehole p2 is obtained by multiplying the pressure per unit length with the
length of the borehole in which the drilling fluid is flowing:

p2 =

dp
×L
dz

(22.3)

where:

dp/dz is the flow resistance per unit length of borehole, in kN/m3 ;
L
is the distance in the borehole between the boring front and the exit point of the
drilling fluid, in m.

Flow resistance dp/dz
The minimum required pressure dp/dz is the optimal value for which the calculated flow rate
Q is equal to the requested flow rate Qreq (necessary to initiate flow of drilling fluid).
Calculated flow rate Q
The calculated flow rate Q is the contribution of five components:
Q = Q1,1 + Q1,2 + Q2 + Q3,1 + Q3,2

(22.4)

with:

R0
1
dp R12
R0
1 2
τdf R03
2
2
2
−
−
λ
R
ln
R
+
C
R
Q1,1 = −2π −
−
2 0
0
3µdf
dz 4µdf
4R12
R1
2 0
2
(22.5)

τdf r03
dp R12
r0
r0
1 2
1
2
2
2
−
λ
r
ln
Q1,2 = 2π −
−
−
r
+
C
r
2
0
0
3µdf
dz 4µdf
4R12
R1
2 0
2
"
!#

τdf
dp R12
r0
r0
Q2 = π r12 − r02 − r0 −
− 2λ2 ln
+ C2
µdf
dz 4µdf
R1
R1

τdf 3 dp R12
r1
r1
1 2
1
2
2
2
Q3,1 = −2π
r −
− λ r1 ln
− r1 + C4 r1
3µdf 1 dz 4µdf
4R12
R1
2
2

4
τdf 3 dp R1 1
Q3,2 = 2π
R −
+ λ2 + C4
3µdf 1 dz 8µdf 2

(22.6)
(22.7)
(22.8)
(22.9)

where:

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τdf

is the yield point of the drilling fluid, as defined in the Drilling Fluid Data window
(section 4.6.4), in kN/m2 ;
is the plastic viscosity of the drilling fluid, as defined in the Drilling Fluid Data window
(section 4.6.4), in kN.s/m2 .

µdf

The constants are:

2τdf × r0
λ = 2 dp +
R1 × dz
2

r0
R1

2
(22.10)

2
2

4τdf
R0
r0
R0
R0
C2 = 2 dp × r0 × ln
− R0 −
+2
× ln
R1
R1
R1
R1
R1 × dz
(22.11)

4τdf
−1
dp
R1 × dz
2τdf
r1 = dp + r0
C4 =

(22.12)
(22.13)

r0 is the solution to the following equation:
"
!
!#

τdf2
2τdf
R0
1 dp 2
2
1
+
ln
+
τ
r
+
r
−
τ
(R
+
R
)
+
R
−
R
df
0
0
df
0
1
1
0
dp
dp
r0 R1
4 dz
dz
dz
"
#
!
1 dp 2
2τdf
R0
r0 ln
=0
(22.14)
+
+ r0
dp
2 dz
r0 R1
dz
Requested flow rate Qreq
The requested flow rate Qreq is equal to:

Qreq = Qann × (1 − floss )

(22.15)

where:

floss is the circulation loss factor;
Qann is the annular back flow rate, in kN/m3 .
22.1.3

Minimum drilling fluid pressure for Stage 1 (pilot pipe in the pilot hole)
For the first drilling stage of the horizontal directional drilling process, the minimum drilling fluid
pressure is calculated for the drilling direction from the left and the right, using the following
formulas:

p
p

pilot
min,left

= p1 + Lleft ×

pilot
min,right

dp
dz

(22.16)
pilot

= p1 + (L − Lleft ) ×

dp
dz

(22.17)
pilot

where:

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Lleft

is the distance in the borehole between the drilling head and the left exit point of the
drilling fluid, in m;
is the total length of the borehole, in m.

L
22.1.4

Minimum drilling fluid pressure for Stage 2 (drill pipe in the pre-ream hole)

"
p

pre-ream
min,left

= min P

pilot
min,right

; p1 + Lleft ×

dp
dz

"
p

22.1.5

pre-ream
min,right

= min P

pilot
min,left

(22.18)
pre-ream

; p1 + (L − Lleft ) ×

dp
dz

(22.19)
pre-ream

Minimum drilling fluid pressure for Stage 3 (product pipe in the borehole)

"
pre-ream
ppull
min,left = min Pmin,right ; p1 + Lleft ×

dp
dz

#
(22.20)
pull

"
pre-ream
ppull
min,right = min Pmin,left ; p1 + (L − Lleft ) ×

22.2

dp
dz

#
(22.21)
pull

Maximum allowable drilling fluid pressure
In the borehole, an excess drilling fluid pressure is maintained to enable sufficient outflow
of drilling fluid and cuttings. At high pressures, the borehole will fail through uncontrolled
expansion. The cavity expansion theory describes the definition of the maximum allowable
drilling fluid pressure at which the wall of the borehole becomes unstable. Such limit pressure
is the highest pressure that can be sustained by a cavity in the soil. Logically, this forms an
upper boundary for the drilling fluid pressure in the borehole.
When the borehole is created, the drilling fluid will exert pressure on the soil. When the
pressure rises above a certain value, plastic deformation of the soil will occur, initially adjacent
to the borehole. When the pressure is increased further beyond this value, the zone with
plastic deformation will increase. If the zone with plastic deformation reaches the surface a
blow-out will occur.
In granular materials (drained soil layers), the drilling fluid pressure may lead to development
of cracks around the borehole when the pressure exceeds a certain maximal value which is
related to the strain of the borehole wall.
In order to prevent blow-outs or damage to structures close to the borehole, care should
be taken that the plastic zone remains within a safe radius around the hole. Therefore the
pressure that creates a plastic zone that does not extend beyond the established safe radius
must be determined.
To determine the maximum allowable drilling fluid pressure, different formulas are used, depending on the soil material sequence above the pipeline.

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22.2.1

Maximum allowable drilling fluid pressure in undrained layers
In undrained layers, the maximum allowable drilling fluid pressure pmax;und is:

"
pmax;und = σ00 + Cu;f 1 − ln

Cu;f
+
Gf

R0
Rp;max

2 !#
+ u ≤ 0.9 plim;und

(22.22)

with:

plim;und = σ0 + Cu;f 1 − ln
σ00 =

Cu;f
Gf

(22.23)

3 σv0
4 fγ

(22.24)

where:

plim;und
Cu,f
fc
cu
σ0 ’
σv ’
fγ
Gf
fE
Rb
Rp,max

H
u

is the limit drilling fluid pressure, in kN/m2 ;
is the average factorized undrained cohesion, in kN/m2 : Cu;f = Cu /fc ;
is the partial safety factor on the cohesion.The default value is set to 1.4;
is the average undrained cohesion, in kN/m2 ;
is the initial effective stress, in kN/m2 ;
is the vertical effective stress at the pipe center, in kN/m2 ;
Partial safety factor on the unit weight.
is the average factorized shear modulus, in kN/m2 : Gf = f ×2E(1+ν) ;
E
is the partial safety factor on Young modulus;
is the radius of the hole, in m;
is the maximum allowable radius of the plastic zone, in m: Rp;max = 0.5 H . The
default ratio between Rp;max and the soil cover H (default 0.5) can be defined by
the user in the Factors window (section 4.7.1.1) under the field Safety factor cover
(Undrained layer);
is the vertical distance between the ground level and the pipe center, in m;
is the pore pressure at pipe center, in kN/m2 , see Equation 26.4.

Note: Parameters Cu;f and Gf are determined using the distance depth average between
the ground level and the pipe centre. For example, the weight average undrained cohesion in
the configuration in Figure 22.1 is:

Cu,2 ×
cu =

Deltares

1
h1

−

1
h1 +h2

1
0.5Do

+ Cu,1 ×
−

1
h1 +h2

1
0.5Do

−

1
h1

(22.25)

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Figure 22.1: Schematization of h1 and h2

In case no data about the undrained strength of the soil is available, an estimated cu value
can be obtained using the subsequent formula:

cu = c × cos ϕ + p × sin ϕ

(22.26)

σv0 + σh0
p=
2

(22.27)

with:

22.2.2

Maximum allowable drilling fluid pressure in drained layers
According to article E.2.2 of NEN 3650-1 (NEN, 2012a), the maximum allowable drilling fluid
pressure in non-compressible drained layers pmax;d is:

pmax;d = (p0f + cf × cot ϕf )

Rb
Rp;max

− sin ϕf
# 1+sin
ϕ

+Q
− cf × cot ϕf + u ≤ 0.9 plim;d (22.28)

with:
− sin ϕf

plim;d = (p0f + cf × cot ϕf ) × Q 1+sin ϕf − cf × cot ϕf + u
p0f = σ00 × (1 + sin ϕf ) + cf × cos ϕf

(22.29)
(22.30)

where:

plim;d
p0f
σ0 ’
ϕf
cf
Rb
Q
Gf

is the limit drilling fluid pressure, in kN/m2 ;
is the effective drilling fluid pressure at which the first plastic deformation appears,
in kN/m2 ;
is the initial effective stress of the soil, in kN/m2 : σ00 = 43 σv0 /fγ ;
is the factorized friction angle, in ◦ : ϕf = arctan (tan ϕ/fϕ );
is the average factorized cohesion, in kN/m2 : cf = c/fc ;
is the radius of the borehole, in m;
is (σ00 × sin ϕf + cf × cos ϕf ) /G;
is the average factorized shear modulus between the border of compressible/nonE
;
compressible layers and the pipe center, in kN/m2 : Gf = f ×2(1+ν)
E

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Rp;max is the maximum allowable radius of the plastic zone, in m. The plastic zone can
be related:
either to the soil cover: Rp;max = 0.5 H

or to the deformation of the bore hole: Rp;max =

Rb2
Q

× 2 εg;max

The calculation of the maximum drilling fluid pressure is performed using values
determined by both methods for the calculation of the maximum allowable radius
of the plastic deformation zone Rp;max , after which the minimum value for the
maximum allowable drilling fluid pressure is taken.
u
is the pore pressure at pipe center, in kN/m2 ;
H
is the distance between the border of compressible/non-compressible layers and
the pipe center, in m;
εg;max is the maximum deformation of the borehole. For sand, εg;max = 0.05.
For the definition of the other symbols, refer to section 23.5.2.

Parameters c, ϕ and G are determined using two methods:

Linear weighted average between the ground level and the pipe center;
Distance depth average between the ground level and the pipe center.
22.3

Equivalent diameter for a bundled pipeline
In case of a bundled pipeline, the following equivalent diameter is used for the calculation of
the drilling fluid pressures during the pull back operation:

Deq

v
u n
uX
=t
D2

o;i

(22.31)

i=1

Note: This equivalent diameter is calculated by D-G EO P IPELINE in the Drilling Fluid Data
window of the Pipe menu.
22.4

Equilibrium between drilling fluid pressure and pore pressure
The ratio between the static pressure of the drilling fluid column p1 and the pore pressure
u yields the safety factor, which should be higher than the (user-defined) requested safety
factor, which writes:

p1
≥ fpress;bore
u

(22.32)

where:

u
fpress;bore

Deltares

is the static pressure of the drilling fluid column (i.e. pressure due to the
difference of level between the drilling head and the exit point of the drilling
fluid), in kN/m2 , see Equation 22.2 in section 22.1.1:
p1 = γdf × (Zexit − Z);
is the calculated pore pressure (see Equation 26.4 in section 26.5);
is the required safety factor, as defined in the Factors window under the field
Contingency factor – Pressure borehole, see section 4.7.1.1.

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23 Strength pipeline calculation
23.1

Buoyancy control
The friction between soil and pipe is partially caused by buoyancy of the pipeline in the drilling
fluid. Uplift forces resulting from buoyancy can be neutralized by filling the pipeline. The
optimal volume of water (Pw ) placed in the pipe provides the most advantageous distribution
of buoyant forces, as illustrated in Figure 23.1.

Figure 23.1: Schematization of the buoyancy control

The forces acting on the pipeline are:
a) Uplift force:

Quplift =

π
× Do2 × γdf
4

(23.1)

b) Weight of the pipeline:

Qpipe =

π
× Do2 − Di2 × γb
4

(23.2)

c) Weight of the filling (water):

Qfilling =

π
× Di2 × γw × Pw
4

(23.3)

The weight of the pipeline filled with water is therefore:

Q = Qpipe + Qfilling

(23.4)

and the effective weight of the pipeline is defined as:

Qeff = |Q − Quplift |

Deltares

(23.5)

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23.2

Pulling force in a flexible pipeline
According to article E.1.2.1 of NEN 3650-1 (NEN, 2012a), the total pulling force is the contribution of five components:

T = T1 + T2 + T3a + T3b + T3c
23.2.1

(23.6)

Roller-lane
According to article E.1.2.2 of NEN 3650-1 (NEN, 2012a), the design pulling force due to
friction of the pipeline on the roller-lane T1 is:

T1 = finstall × Lrol × Q × f1

(23.7)

where:

finstall is the total factor for stochastic variation and model uncertainty, called Load factor
installation in the Factors window (section 4.7.1.1). The default value is set to 1.1;
is the length of the pipeline on the roller-lane, in mm;
is the weight of the pipeline filled with water, in N/mm, see Equation 23.4;
is the factor of friction of the roller-lane, defined in the Engineering Data window, see
section 4.6.3.1. The default value is set to 0.1.

Lrol
Q
f1

23.2.2

Straight part of the borehole
According to article E.1.2.3 of NEN 3650-1 (NEN, 2012a), the pulling force in the straight part
of the borehole due to friction between pipe and drilling fluid is:

T2 = finstall × L2 × (π Do × f2 + Qeff × f3 )

(23.8)

where:

finstall is the total factor for stochastic variation and model uncertainty, called Load factor
installation in the Factors window (section 4.7.1.1). The default value is set to 1.1;
is the length of the pipeline in the straight part of the borehole, in mm;
is the friction between the pipeline and the drilling fluid, in N/mm2 , defined in
the Engineering Data window, see section 4.6.3.1. The default value is set to
0.00005 N/mm2 ;
is the effective weight of the pipeline, in N/mm, see Equation 23.5;
is the factor of friction between the pipeline and the borehole wall, defined in the
Engineering Data window, see section 4.6.3.1. The default value is set to 0.2.

L2
f2
Qeff
f3

23.2.3

Curved part of the borehole
According to article E.1.2.4.1 of NEN 3650-1 (NEN, 2012a), the pulling force in the curved
part of the borehole due to friction between pipe and drilling fluid T3a is:

T3a = finstall × Lb × (π Do × f2 + Qeff × f3 )

(23.9)

where:

is the length of the pipeline in the curved part of the borehole, in mm.
For the definition of the other symbols, refer to section 23.5.2.

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23.2.4

Friction due to soil reaction in the curved part
According to article E.1.2.4.2 of NEN 3650-1 (NEN, 2012a), the pulling force in the curved
part of the borehole due to soil reaction T3b is:

T3b = finstall × 4 ×

π
qr
× Do × × f3
2
λ

(23.10)

with:

qr = kv × y
0.3224 × λ2 × Eb × Ib
y=
Do × R
r
Do
λ = 4 fkv × kv ×
4Eb Ib

(23.11)
(23.12)
(23.13)

where:
is the maximum soil reaction, in N/mm2 ;
is the vertical modulus of subgrade reaction, in N/mm3 ;
is the maximum displacement, in mm;
is the characteristic stiffness pipeline-soil, in mm-1 ;
is the contingency factor on the modulus of subgrade reaction. The default value is
1.6;
is the Young’s modulus of the pipe, in N/mm2 ;
is the moment of inertia of the pipe, in mm4 ;
is the bending radius, in mm;
is the factor of friction between the pipeline and the borehole wall, defined in the
Engineering Data window, see section 4.6.3.1. The default value is set to 0.2.

qr
kv
y
λ
fkv
Eb
Ib
R
f3

23.2.5

Friction due to curved forces
According to article E.1.2.4.3 of NEN 3650-1 (NEN, 2012a), the pulling force in the curved
part of the borehole due to curved forces T3c is:

T3c = finstall × Lb × gt × f3

(23.14)

where:

Lb
α
gt
T

is the length of the curve, in mm: Lb = 2 × R × 2π × α/360;
is the half angle of the curved part, in degrees;
is the curved force, in N/mm: gt = (2 T sin α) /Lb ;
is the total pulling force in the pipeline, in N, see Equation 23.6.

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23.3

Maximum representative pulling force
The maximum representative pulling force Tmax;rep in a single pipeline is:

For steel pipe:
Pmax;rep

1
2 − 4 −2.25 R2 + σ 2
− σb (23.15)
= A × 2 −σqr + σqr
qr
eb

For polyethylene pipe:
Pmax;rep = A × (Reb;short − α × σb )

(23.16)

where:

A
Reb
Reb;short
α
δt
σqr
σb
23.4

is the cross-section of the pipe, in mm2 : A = π × (r02 − ri2 );
is the allowable strength for steel, in N/mm2 , as defined in the Product Pipe
Material Data window (see section 4.6.2.1);
is the allowable strength at short term for PE, in N/mm2 , as defined in the Product
Pipe Material Data window (see section 4.6.2.1);
is the tensile factor, as defined in the Product Pipe Material Data window (see
section 4.6.2.1);
is the negative wall thickness tolerance, in %, as defined in the Product Pipe
Material Data window (see section 4.6.2.1);
is the maximum tangential stress in LC 1B, in N/mm2 , see Equation 23.31;
is the axial stress in LC 1B, in N/mm2 , see Equation 23.27.

Pulling force for a bundled pipeline
Important parameters for the pullback operation are the total weight of the (filled/ not filled)
pipelines with respect to drilling fluid, which determines the soil reaction force on the bore hole
wall in straight sections of the drilling line and the total stiffness of the bundled pipeline, which
determines the soil reaction force in curved sections of the drilling line. The pulling force is
calculated for an equivalent pipeline with the parameters of the bundle.

EIeq =

n
X

EIi

(23.17)

i=1

Gtot =

n
X
1
i=1

Deq = f ×

2
πD0;i

n
X

1
− π (D0;i − 2dn;i )2
4

Do;i

× γi

(23.18)

(23.19)

i=1

The equivalent diameter can be used to determine the equivalent wall thickness of the pipeline:

1
Gtot
2
= π Deq
− (Deq − 2dn;eq )2
γeq
4
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(23.20)

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Strength pipeline calculation

s
Deq −

n
X
2
D0;i
− (Do;i − 2dn;i )2
eq −

i=1

dn;eq =

(23.21)

where:

n
Do;i
Deq
dn;i
dn;eq
γi
γeq
f

is the number of pipelines in bundle;
is the outer diameter of pipeline number i, in m;
is the equivalent diameter of the pipeline, in m;
is the wall thickness of pipeline number i, in m;
is the equivalent wall thickness of the pipeline, in m;
is the unit weight of the material of pipeline number i, in kN/m3 ;
is the equivalent unit weight of the pipeline material, in kN/m3 ;
is a factor: f = 1/n0.3 .

The calculated pulling force is acting on all the pipelines in the bundle. The magnitude of the
pulling force of a single pipeline can be determined as follows:

Ti =

π
4
n
X

2
−
Do;i
π
4

π
4

2
Do;i
−

(Do;i − 2 dn;i )2
π
4

× Ttotal

(23.22)

(Do;i − 2 dn;i )2

i=1

In case the stiffness of the pipeline materials is significantly different (for example a combined
bundle of steel and PE pipelines), a different approach is applied. In addition to the previous
align, the total pulling force is divided over the stiff steel pipelines. The PE pipelines are then
considered as single pulled in pipelines.
23.5

Strength calculation
In order to consider the strength of the pipeline, calculations for five load combinations are
carried out according to NEN 3650:

23.5.1

Load combination 1A: start of the pullback operation (section 23.5.1)
Load combination 1B: end of the pullback operation (section 23.5.2)
Load combination 2: application of internal pressure (section 23.5.3)
Load combination 3: pipeline in operation, without internal pressure (section 23.5.4)
Load combination 4 : pipeline in operation, with internal pressure (section 23.5.5)

Strength calculation for Load Combination 1A: start of the pullback operation
Axial stress:
At start of the pull back operation, the axial bending stress σb is:

σb =

Mb
fk × Eb × Ib
=
Wb
Rrol × Wb

(23.23)

Note: fk is the overall safety factor on moment, as prescribed in article E.1.3 of NEN 3650-1.

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In D-G EO P IPELINE, this overall factor is indeed the contribution of three safety factors:

fk =

fM × finstall
fR

(23.24)

where:

fM
is the contingency factor on moment: 1.27 for steel pipe and 1.4 for PE pipe;
fR
is the contingency factor on bending radius: 1.1 for steel pipe and 1 for PE pipe;
finstall is the load factor on installation: 1.1 for steel pipe and 1 for PE pipe.

The axial stress due to pull-back is:

σt = fpull ×

T1
A

(23.25)

where:

is the design pulling force due to friction of the pipeline on the roller-lane, see Equation 23.7.
For the definition of the other symbols, refer to section 23.5.2.

The maximum axial stress is:

σa;max = max (|σt + α × σb | ; |σt − α × σb |)

(23.26)

Tangential stress:
At start of the pull back operation, the pipeline is situated on the rollers, the tangential stress
is negligible.
23.5.2

Strength calculation for Load Combination 1B: end of the pullback operation
Axial stresses:
At the end of the pull back operation, the axial bending stress:

σb =

Mb
fk × Eb × Ib
=
Wb
Rmin × Wb

(23.27)

The axial stress due to pull-back is:

σt = fpull ×

Tmax
A

(23.28)

The maximum axial stress is:

σa;max = max (|σt + α × σb | ; |σt − α × σb |)

(23.29)

where:

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Rmin is the minimum bending radius of the pipeline configuration (i.e. minimum between
Rleft , Rright and the horizontal bending radius), in m. In case of a combined 3dimensional bending radius, see Equation 20.5.

Tmax is the maximum pulling force, in kN (see section 23.2).
Note: fk is the overall safety factor on moment, as prescribed in article E.1.3 of NEN 3650-1.
In D-G EO P IPELINE, this overall factor is indeed the contribution of three safety factors:

fk =

fM × finstall
fR

(23.30)

Tangential stresses:
The tangential stress (indirectly transmitted) as a result of the bending is:

σqr = max (σqr;b ; σqr;t )

(23.31)

with:

rg
× Do
Ww
rg
= Kt0 × qr ×
× Do
Ww

σqr;b = Kb0 × qr ×

(at the bottom of the pipe)

σqr;t

(at the top of the pipe)

where:
is the soil reaction, in kN/m2 , see Equation 23.11 with R = the minimum bending
radius;
Kb ’ is the moment coefficient for indirectly transmitted stress at the bottom of the
pipeline, depending on the bedding angle β as shown in Table 23.12;
Kt ’ is the moment coefficient for indirectly transmitted stress at the top of the pipeline,
depending on the bedding angle β as shown in Table 23.12;
Ww is the wall resisting moment in m3 /m: Ww = d2n /6.
For the definition of the other symbols, refer to section 23.5.2.

The maximum tangential stress is:

σt;max = σqr

23.5.3

(23.32)

Strength calculation for Load Combination 2: application of internal pressure
According to article 8.5.2.1 of NEN 3651 (NEN, 2012d), the ring stresses around the pipeline
σpy and σpt caused by design (pd ) respectively test (pt ) internal pressure are:

For piles with a thin wall (Dg /d < 20):
σpy = fpd × pd ×

σpt = fpt × pt ×

Deltares

Dg
2×d

(23.33)

(23.34)

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Table 23.12: Moment and deflection coefficients for indirectly and directly transmitted
stress as a function of the bedding angle β , according to Table D.2 of
NEN 3650-1

Load angle

β
◦

0
30◦
60◦
70◦
90◦
120◦
150◦
180◦

Direct coefficients

Indirect coefficients

Kt0

Kb0

ky0

0.150
0.148
0.143
0.141
0.137
0.131
0.126
0.125

0.294
0.235
0.189
0.178
0.157
0.138
0.128
0.125

0.116
0.113
0.105
0.102
0.096
0.089
0.085
0.083

0.080
0.078
0.073
0.071
0.067
0.061
0.056
0.055

0.239
0.179
0.134
0.122
0.102
0.083
0.073
0.070

0.074
0.071
0.064
0.061
0.055
0.048
0.043
0.042

For piles with a thick wall (Dg /d ≥ 20):
σpy = fpd × pd ×

σpt = fpt × pt ×

r02 + ri2
r02 − ri2

(23.35)

r02 + ri2
r02 − ri2

(23.36)

The axial internal stress σpx is:

σpx = ν × σpt = 0.5 × σpt
23.5.4

(23.37)

Strength calculation for Load Combination 3: pipeline in operation, without internal
pressure
Axial stresses:
When the pipeline is in operation, the axial bending stress σb is:

σb =

fk × Eb × Ib
Mb
=
Wb
Rmin × Wb

(23.38)

The maximum axial stress is:

σa;max = α × σb

(23.39)

Tangential stresses:
The tangential stress (indirectly transmitted) as a result of the bending is:

σqr = max (σqr;b ; σqr;t )

(23.40)

with:

rg
× Do
Ww
rg
= Kt0 × qr ×
× Do
Ww

σqr;b = Kb0 × qr ×

(at the bottom of the pipe)

σqr;t

(at the top of the pipe)

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The tangential stress (directly transmitted) as a result of the bending is:

σqn = max (σqn;b ; σqn;t )

(23.41)

with:

rg
× Do
Ww
rg
× Do
= Kt × qn,r,v ×
Ww
= fQn1 × fQn2 × (qn,r + qv )

σqn;b = Kb × qn,r,v ×

(at the bottom of the pipe)

σqn;t

(at the top of the pipe)

qn,r,v

The maximum tangential stress is:

σt;max = α × max (|σqr;b + σqn;b | ; |σqr;t + σqn;t |)

(23.42)

where:

fQn1

is the load factor on soil stress qn , as defined in the Factors window (see section 4.7.1.1). The default value is set to 1.5 for steel and 1 for polyethylene;
fQn2 is the contingency factor on soil stress qn , as defined in the Factors window (see
section 4.7.1.1). The default value is set to 1.1;
Kb
is the moment coefficient for directly transmitted stress at the bottom of the pipeline,
depending on the bedding angle β as shown in Table 23.12;
Kt
is the moment coefficient for directly transmitted stress at the top of the pipeline,
depending on the bedding angle β as shown in Table 23.12;
qn,r,v is the (maximum) reduced vertical stress qn,r increased with a possible traffic load
qv , including safety factors, in kN/m2 ;
qn,r
is the neutral reduced soil stress, in kN/m2 , see section 21.3;
qv
is the traffic load, in kN/m2 , see section 21.14;
For the definition of the other symbols, refer to section 23.5.2.

23.5.5

Strength calculation for Load Combination 4: pipeline in operation, with internal
pressure
Axial stresses:
The axial bending stress σb is:

σb =

Mb
fk × Eb × Ib
=
Wb
Rmin × Wb

(23.43)

The ring stresses around the pipeline caused by design internal pressure and σpy and test
internal pressure σpt are

Do − d
2×d
Do − d
σpt = fpt × pt ×
2×d
r02 + ri2
σpt = fpt × pt × 2
r0 − ri2
σpy = fpd;comb × pd ×

Deltares

(23.44)
for steel

(23.45)

for polyethylene

(23.46)

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The axial internal stress σpx is:

σpx = ν × σpy = 0.5 σpy

(23.47)

The axial internal stress due to temperature variation σtemp is, according to article D.2.2 of
NEN 3650-1:

σtemp = ∆t × αg × Eb

(23.48)

where:

∆t
αg
Eb

is the temperature variation in ◦ c, as defined in the Product Pipe Material Data
window, see section 4.6.2.1;
is the linear settlement coefficient, in (mm/mm)K−1 , as defined in the Engineering
Data window, see section 4.6.3.1;
is the Young’s modulus of the pipe (at long term for polyethylene), in kN/m2 .

The maximum axial stress is:

σa;max = α × σb + σpx

(23.49)

Tangential stresses:
The tangential stress (indirectly transmitted) as a result of the bending is:

σqr = max (σqr;b ; σqr;t )

(23.50)

with:

rg
× Do
Ww
rg
× Do
= Kt0 × qr ×
Ww

σqr;b = Kb0 × qr ×

(at the bottom of the pipe)

σqr;t

(at the top of the pipe)

The tangential stress (directly transmitted) as a result of the bending is:

σqn = max (σqn;b ; σqn;t )

(23.51)

with:

rg
× Do
Ww
rg
= Kt × qn,r,v ×
× Do
Ww
= fQn1 × fQn2 × (qn,r + qv )

σqn;b = Kb × qn,r,v ×

(at the bottom of the pipe)

σqn;t

(at the top of the pipe)

qn,r,v

Refer to section 23.5.4 for the definition of the symbols.
The maximum tangential stress is:

σt;max = σpy + α × (Frr0 × σqr + Frr × σqn )

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(23.52)

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with:

Frr =
1+
Frr0 =
1+

1
2pd × rg3 × ky

(23.53)

Eb ×Iw

1
2pd × rg3 × ky0

(23.54)

Eb ×Iw

where:

Frr
Frr ’
Iw
ky

is the direct re-rounding factor;
is the indirect re-rounding factor;
is the moment of inertia of the wall, in m3 : Iw = d3n /12;
is the direct deflection factor depending on the bedding angle β as shown in Table 23.12;
ky ’
is the indirect deflection factor depending on the bedding angle β as shown in Table 23.12;
For the definition of the other symbols, refer to section 23.5.2.

23.6
23.6.1
23.6.1.1

Check of calculated stresses
Check of calculated stresses according to the Dutch standard NEN
Check of calculated stresses acc. to the Dutch standard NEN: Steel pipe
According to article D.3.1 of NEN 3650-2 (NEN, 2012b), the calculated stresses (for the load
combinations) must meet the following conditions:

For Load Combinations 1A and 1B:
σV ≤ Reb /γm

(23.55)

For Load Combination 2:
σpy ≤ Reb /γm
σpt ≤ Reb /γm;test
σpm ≤ 1.1 Reb /γm

(23.56)
(23.57)
(23.58)

For Load Combinations 3 and 4:
σV;max ≤ 0.85 (Reb + Re;20◦ ) /γm

(23.59)

with:

q
σx2 + σy2 − σx × σy
q
2
2
σV;i = σx;i
+ σy;i
− σx;i × σy;i
q
2 + σ2 − σ × σ
σpm = σpx
px
py
py
σV =

(23.60)
(23.61)
(23.62)

where:

σV;max is the maximum acting stress, in kN/m2 : σV;max = max (σV;1 ; σV;2 ; σV;3 ; σV;4 );

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is the calculated acting stress, in kN/m2 :
– i=1 (σV;1 ) corresponds to the primary membrane stress
– i=2 (σV;2 ) corresponds to the total primary stress
– i=3 (σV;3 ) corresponds to the total membrane stress
– i=4 (σV;4 ) corresponds to the resultant of primary and secondary stresses.
For the determination of σV;i , four combinations of (σx;i ; σy;i ) are tested (top and
bottom of the pipe combined with inside or outside), and the maximum value is
used for the check. Those four combinations are given in Table 23.17 to Table 23.20;
is the tangential stress due to design pressure, in kN/m2 ;
is the tangential stress due to test pressure, in kN/m2 ;
is the axial stress, in kN/m2 ;
is the tangential stress, in kN/m2 ;
is the partial material factor, as defined in the Product Pipe Material Data window
(see section 4.6.2.1;
is the partial material factor for test pressure, as defined in the Product Pipe Material Data window (see section 4.6.2.1;
is the yield strength, in kN/m2 , as defined in the Product Pipe Material Data window
(see section 4.6.2.1);
is the yield strength at a temperature of 20◦ c, in kN/m2 .

σV;i

σpy
σptest
σx;i
σy;i
γm
γm;test
Reb
Re;20

Table 23.17: Set for calculation of the maximum stresses for load combination 1A

σx
σy

Top outside

Top inside

Bottom inside

Bottom outside

σt − α × σb

σt + α × σb

Table 23.18: Set for calculation of the maximum stresses for load combination 1B

σx
σy

Top outside

Top inside

Bottom inside

Bottom outside

σt − α × σb
−σqr;t

σt − α × σb
σqr;t

σt + α × σb
σqr;b

σt + α × σb
−σqr;b

Table 23.19: Set for calculation of the maximum stresses for load combination 3

σx;2
σy;2
σx;3
σy;3
σx;4
σy;4

Top outside
0

Top inside
0

Bottom inside
0

Bottom outside
0

−σqr;t
−α × σb

σqr;t
−α × σb

σqr;b
α × σb

−σqr;b
α × σb

−α × σb
−σqr;t − σqn;t

−α × σb
σqr;t + σqn;t

α × σb
σqr;b + σqn;b

α × σb
−σqr;b − σqn;b

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Table 23.20: Set for calculation of the maximum stresses for load combination 4

σx;1
σy;1
σx;2
σy;2
σx;3
σy;3
σx;4
σy;4

Top outside

Top inside

Bottom inside

Bottom outside

σpx
σpy
σpx
σpy − Frr × σqn;t
σpx − α × σb
σpy
σpx − α × σb
σpy − α(Frr × σqn;t
+Frr0 × σqr;t )

σpx
σpy
σpx
σpy + Frr × σqn;t
σpx − α × σb
σpy
σpx − α × σb
σpy + α(Frr × σqn;t
+Frr0 × σqr;t )

σpx
σpy
σpx
σpy + Frr × σqn;b
σpx + α × σb
σpy
σpx + α × σb
σpy +α(Frr ×σqn;b
+Frr0 × σqr;b )

σpx
σpy
σpx
σpy − Frr × σqn;b
σpx + α × σb
σpy
σpx + α × σb
σpy −α(Frr ×σqn;b
+Frr0 × σqr;b )

Note: α is the tensile factor (only used for polyethylene), as defined in the Product Pipe
Material Data window (see section 4.6.2.1).
Note: For load combination 4, the acting stresses σV;1 to σV;4 are calculated with a load
factor “in combination” (fpd;comb ) for the design pressure.
23.6.1.2

Check of calculated stresses acc. to the Dutch standard NEN: Polyethylene pipe
The calculated stresses must meet the following conditions:

σ ≤ S × Reb;short
σ ≤ S × Reb;long

for LC 1 and 2 (test pressure)

(23.63)

for LC 2 (internal pressure), 3 and 4

(23.64)

where:

σ
is the calculated stress, in kN/m2 ;
Reb;short is the allowable strength at short term, in kN/m2 ;
Reb;long is the allowable strength at long term, in kN/m2 ;
S
is the factor of importance, as defined in the Factors window (see section 4.7.1.1).
23.7

Deflection of the pipe
According to article D.4.2 (case 5 - HDD) of NEN 3650-1 (NEN, 2012a), the deflection of the
pipeline is:

δy =

Do × rg3
× ky × qn,r,v + 0.083 × qh,r + ky0 × qr
Eb × Iw

(23.65)

where:

qn,r,v is the corrected neutral reduced vertical stress qn;r (see section 21.3) increased
with a possible traffic load qv (see section 21.14), including safety factors, in kN/m2 :
qn,r,v = fQn1 × fQn2 × (qn;r + qv );
qh,r is the neutral reduced horizontal stress in kN/m2 , see Equation 21.12;
qr
is the soil reaction in kN/m2 , see Equation 23.11 with R = the minimum bending
ky
ky ’

radius.
is the direct deflection coefficient depending on the bedding angle β , see Table 23.12;
is the indirect deflection coefficient depending on the bedding angle β , see Table 23.12;

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fQn1 is the load factor on soil stress qn , as defined in the Factors window (see section 4.7.1.1). The default value is set to 1.5 for steel and 1 for polyethylene;

fQn2 is the contingency factor on soil stress qn , as defined in the Factors window (see
section 4.7.1.1). The default value is set to 1.1;
is the Young’s modulus of the pipe. For PE, the modulus at long term is used.

Eb
23.8

Implosion of the polyethylene pipe
According to article 8.5.5.1 of NEN 3650-3 for polyethylene, the maximum allowable external
pressure p0 is:

p0 =

γimp

24 × Eb × Iw
1
×
2
(1 − ν )
Dg3

(23.66)

where:
is the Young’s modulus of the polyethylene pipe, in kN/m2 ;
is the Poisson ratio of polyethylene: ν = 0.4;
is the safety factor on implosion, as defined in the Factors window (see section 4.7.1.1).
For the definition of the other symbols, refer to section 23.5.2.

Eb
ν
γimp

The check on implosion is performed during the pull-back operation (section 23.8.1) and at
serviceability limit state when the pipe is in operation (section 23.8.2).
23.8.1

Check on implosion during the pull-back operation
During the pull-back operation, the drilling fluid pressure gives an external pressure on the
pipe. The highest minimum required drilling fluid pressure should not exceed the maximum
allowable external pressure. This writes:

max (pmud;min ) ≤ p0

(23.67)

where γ = 1.5 and E is the module at short term, for the calculation of p0 .
If the pipe is completely filled, the filling fluid gives an internal fluid pressure called filling
resistance pfill of:

pfill = (min (Zleft ; Zright ) − Zbottom ) × γfill

(23.68)

The maximum allowable external pressure becomes therefore p0 + pfill and the check on
implosion becomes:

max (pmud;min ) ≤ p0 + pfill
23.8.2

(23.69)

Check on implosion when the pipe is in operation
In operation, the water pressure at the lowest point of the drilling gives an external pressure
on the pipe. This maximum pore pressure should not exceed the maximum allowable external
pressure. This writes:

umax ≤ p0

(23.70)

where γ = 3 and E is the module at long term, for the calculation of p0 .

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If the pipe is completely filled, the maximum allowable external pressure becomes p0 + pfill
and the check on implosion becomes:

umax ≤ p0 + pfill

Deltares

(23.71)

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24 Micro tunneling
24.1

Support pressures and thrust forces
Drilling through the soil changes the stress conditions in the soil. The deviations from the
original stress conditions are largely determined by the size of the overcut and the face support pressure of the applied shield. Small deviations form the original stress conditions are
acceptable as the stability of soil adjacent to the micro tunneling machine is maintained. A
relative low support pressure may lead to settlement in front of the tunneling machine which in
turn may lead to settlement of the surface or to settlement of soil layers below a construction
or pipeline. A relative high support pressure can lead to a blow out of drilling fluid or may lead
to heave of the surface.

24.1.1

Target support pressure
In order to minimize the effect on the stress conditions, the drilling should be performed using
a target support pressure σT;ac which is close to the neutral horizontal pressure:
0
σT;ac = σh,n
+u

(24.1)

where:
is the pore pressure, in kN/m2 at the shield center, see Equation 26.4.
is the horizontal effective pressure at the shield center, in kN/m2 :
0
σh,n
= σv0 × (1 − sin ϕb );
is the vertical effective stress at the shield center, in kN/m2 , see Equation 26.5;
is the average angle of internal friction of the soil over the height of the shield.

u
0
σh,n
σv0
ϕb
24.1.2

Minimal support pressure
Under normal circumstances, a relative low support pressure is usually sufficient for stable
conditions of the soil adjacent to the micro tunneling machine. The minimal required support
pressure is often a little higher than the water pressure. The relative low required minimal
support pressure is determined by the type of soil in front of the tunneling machine.
Minimal support pressure in undrained conditions
In case of micro tunneling in an undrained soil type, according to Broms & Bennermark 1967
(Broms and Bennermark, 1967), the minimal support pressure σmin;und is determined by the
undrained strength of the soil:

σmin;und = fcover × σv0 + fu × u − N ×

su
≥ fu × u
fc

(24.2)

where:

su
fc
fcover
fu
N

is the average undrained shear strength between the surface and the top of the
shield of the micro tunneling machine , in kN/m2 ;
is the safety factor on cohesion as defined in the Factors window, see section 4.7.1.2
(default is 1.4).
is the contingency factor on soil cover as defined in the Factors window, see section 4.7.1.2 (default is 1.1);
is the safety factor on water pressure as defined in the Factors window, see section 4.7.1.2 (default is 1.05);
is the face stability ratio as defined in the Factors window, see section 4.7.1.2;

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σv0
u

is the vertical effective stress at the shield center, in kN/m2 , see Equation 26.5;
is the pore pressure, see Equation 26.4.

The required stability index N depends upon the depth/diameter ratio of the tunneling machine. In Figure 24.1 the upper and lower boundaries according to (Davis et al., 1980) are
described.

Figure 24.1: Upper and lower bound for the stability ratio N (Davis et al., 1980)

Minimal support pressure in drained conditions
In granular soils which behave drained during drilling, the minimal support pressure based
on 3 dimensional effects can be calculated using the method which is developed by (Jancesz
and Steiner, 1994). The minimal effective stress required for stability of the soil next to the
shield is defined as follows:

σh0 = fσh × KA3 × σv0

(24.3)

The total minimal support pressure is drained layers σmin;d can be calculated as follows:

σmin;d = fσh × KA3 × σv0 + fu × u

(24.4)

where:

fu
fσ h
KA3
u
σh0
σv0

is the safety factor on water pressure as defined in the Factors window, see section 4.7.1.2 (default is 1.05);
is the safety factor on horizontal effective stress as defined in the Factors window,
see section 4.7.1.2 (default is 1.5);
is a 3 dimensional coefficient of active earth pressure, see Equation 24.5;
is the pore pressure, in kN/m2 , see Equation 26.4;
is the effective horizontal soil pressure at the shield center, in kN/m2 ;
is the effective vertical stress at the shield center, in kN/m2 , see Equation 26.5. In
case of arching effect over the depth C1 (i.e. C1 /Do > fsilo ), the vertical effective
0
stress σv0 is reduced to σv;1
as explained below (see Equation 24.6).

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The 3 dimensional coefficient of active earth pressure is calculated as follows:

KA3

sin β × cos β − cos2 β × tan ϕ − 23 K × α × cos β × tan ϕ
=
cos β × sin β + tan ϕ × sin2 β

(24.5)

with:

α=

C1
1 + 3D
o
C1
1 + 2D
o

where:

C1
β
ϕ

is the distance between the drained/undrained border and the top of the shield of
the micro tunneling machine, in m;
is the angle of the slip surface of the active wedge, in degree;
is the angle of internal friction, in degree.

In the subsequent figure the values for different angles of internal friction for a series of
depth/diameter ratios are shown.

Figure 24.2: Values for KA3

The method described by Jancsecz and Steiner Jancesz and Steiner (1994) has the opportunity to take the effect of vertical stress reduction due to arching in account. In Figure 24.3, the
arching over the depth C can reduce the vertical stress on the active wedge which determines
the minimal support pressure. It should be noticed that the arching can only occur if a relative
small soil deformation (settlement of the soil column above the active soil wedge) is allowed.

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Figure 24.3: Active soil wedge with soil column (Broere, 1994)

For a layered soil the following equation can be used to calculate the effect of two dimensional
arching according to Terzaghi (Terzaghi, 1943) on the active wedge:
0

σv;1

× γ 0 − cd
O
Do
=
1 − exp − × C2 × K0 × tan ϕd
× γb0 (24.6)
+
K0 × tan ϕd
A
2
A
O

with:

2 1 + tan
O
=
A
Do × tan

π
2
π
2

−β

where:

A
cd
C2
K0
O
ϕd
γ0
γb0

is the area of the soil column, in m2 ;
is the cohesion of the slip surface of the active wedge (i.e. average between the
drained/undrained border and the top of the shield of the micro tunneling machine),
in kN/m2 ;
is the distance between the ground level and the top of the shield of the micro
tunneling machine, in m;
is the coefficient of neutral earth pressure: K0 = 1 − sin ϕd ;
is the circumference of the soil column, in m;
is the average angle of internal friction between the drained/undrained border and
the top of the shield of the micro tunneling machine, in degrees;
is the average effective unit weight between the ground level and the top of the shield
of the micro tunneling machine, in kN/m3 ;
is the average effective unit weight between the top and the center of the shield of
the micro tunneling machine, in kN/m3 .

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24.1.3

Maximal support pressure
In case of a high support pressure, several possible failure mechanism may occur:

Soil failure due to pushing a soil wedge in upward direction
A blow out to the surface due to hydraulic fracturing
Horizontal hydraulic fracturing at the transition of soil layers
The maximal allowable support pressure σmax for micro tunneling can be determined as follows:

σmax =

σv0
fcover

+ u × fu

(24.7)

where:
is the effective vertical stress (see Equation 26.5);
σv0
u
is the pore pressure, in kN/m2 , see Equation 26.4;
fcover is the contingency factor on soil cover as defined in the Factors window, see section 4.7.1.2 (default is 1.1).
is the safety factor on water pressure as defined in the Factors window, see section 4.7.1.2 (default is 1.05);

Obvious the total allowable support pressure is equal to the sum of the allowable effective
support pressure and the water pressure at the drilling line.
24.1.4

Thrust force
The thrust force which is required to install a pipeline or micro tunnel in between the launch
pit and the reception pit. The magnitude of the thrust force is determined by the pressure on
the shield (head of the tunneling machine) and friction along the circumference of the tunnel
or pipeline. The thrust force due to pressure on the shield is relative small compared to the
force due to friction and can therefore be neglected. The thrust force Fm due to friction can
be calculated as follows:

Fm = π × Do × L × M

(24.8)

where:

Do
L
M

is the diameter of the pipeline or the tunnel, in m;
is the length, in m;
is the friction between the soil and the pipe per surface area, in kN/m2 . The friction
M is defined in the Engineering Data window (section 4.6.3.3) where two cases are
considered: friction with or without injection of lubricant.

The friction per surface area is partly determined by the soil type, through which the micro
tunneling is carried out, but is mainly determined by the overcut and the usage of lubricants,
which reduce the friction in between the tunnel or pipeline and the surrounding soil. Since
the bending radii of the curves in a micro tunneling drilling line are generally smooth the soil
reaction forces in the curves are not considered in D-G EO P IPELINE.

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24.2

Uplift Safety
Due to buoyancy of the pipeline below the groundwater table, the uplift should be checked:

fuplift < fuplift;all

(24.9)

where fuplift;all is the allowable safety factor on uplift, as defined in the Factors window, see
section 4.7.1.2.
The forces acting on the pipeline are:

the uplift force:
guplift =

π
× Do2 × γw
4

(24.10)

the weight of the pipeline:

π
gpipe = × Do2 − (Do − 2dn )2 × γb
4

(24.11)

The effective weight of the pipeline is defined as:

geff = gpipe − guplift

(24.12)

and the uplift safety factor fuplift is:

fuplift =

geff
n
X

(24.13)

γi0 × di

i=1

where:

γi0
n
di
24.3

is the buoyant unit weight of soil layer i, in kN/m3 ;
is the number of soil layers;
is the thickness of soil layer i above the pipeline, in m.

Subsidence
The drilling process micro tunneling leads to a larger amount of removed soil material than the
volume of the installed tunnel or pipeline (Overcut). Of course injection of lubricants may lead
to a reduction of the differential volume of removed soil and installed elements. The differential
volume will lead to soil movement towards the bore hole, which in turn will lead to subsidence.
The magnitude of the subsidence w (trough shaped) can be calculated as follows:

r2
w=√
exp − 2
2i
2πi2
Vs

z < z0

(24.14)

with:

Vloss
Vs =
×
100

2
Do + 2 lovercut 2
Do
−
2
2

where:

is the shape factor, see below;

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lovercut is the overcut in radius, in m;
r
is the horizontal distance in between the center of the tunnel or pipeline and the
z0
z
Vloss
Vs

inflection point of the trough, in m;
is the depth of the center of the pipeline or tunnel, in m;
is the depth at which the settlement is calculated, in m;
is the volume loss as percentage of overcut area, in %, as defined in the Engineering Data window, see section 4.6.3.2;
is the differential volume, in m3 /m.

The shape factor i depends upon the soil behavior above the tunnel or pipeline and is there
dependent upon the soil properties of the upper soil layers. The factor i can empirically be
determined based on differences in soil sequences. The empirical method is described by O
Reilly (O’ Reilly and New, 1982):

i = 0.43 Dbas + 0.28 Dtop + 1.1
i = 0.43 Dbas + 1.1
i = 0.23 Dbas + 0.43 Dtop − 0.1
i = 0.28 Dbas − 0.1

for incompressible granular soil on compressible soil
for compressible soil
for compressible soil on incompressible granular soil
for incompressible granular soil

where:

Dbas
Dtop

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is the thickness of the Basal layer above the tunnel or pipeline, in m;
is the thickness of the upper layer above the tunnel or pipeline, in m.

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25 Trenching
Installation of the pipeline in a trench is the oldest and a relatively easy method. One of
the main installation risk associated with trenching is instability of the slopes of the trench.
This risk can not be considered in D-G EO P IPELINE. Use of other computer programs such as
D-G EO S TABILITY (formerly known as MStab) is recommended.
In case of installed pipelines with a relatively thin soil cover in a wet environment, uplift can
be an installation risk (section 25.1). In case of trenching in soil layers which cover an aquifer
with high pore pressures, bursting of the bottom of the trench (heaving) can be an installation
risk (section 25.2).
25.1

Uplift Safety
Due to buoyancy of the pipeline below the groundwater table, the uplift should be checked:

fuplift < fuplift;all

(25.1)

where fuplift;all is the allowable safety factor on uplift, as defined in the Factors window, see
section 4.7.1.3.
The forces acting on an empty pipe are:

the uplift force:
guplift =

π
× Do2 × γw
4

the weight of the pipeline:

π
gpipe = × Do2 − (Do − 2dn )2 × γb
4

(25.2)

(25.3)

The effective weight of the pipeline is defined as:

geff = gpipe − guplift

(25.4)

and the uplift safety factor fuplift is:

fuplift =

geff
n
X

(25.5)

γi0 × di

i=1

where:

γi0
n
di

is the buoyant unit weight of soil layer i, in kN/m3 ;
is the number of soil layers;
is the thickness of soil layer i above the pipeline, in m.

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25.2

Bursting of the trench bottom (heaving)
The check of the bursting of the trench bottom is performed according to paragraph 14.3.1 of
the Dutch standard NEN 6740:2006 (NEN, 2006). The calculated safety factor fburst should
not exceed the allowable safety factor on hydraulic heave fburst;all , as defined in the Factors
window, see section 4.7.1.3.

fburst;all > fburst

(25.6)

The safety factor on bursting fburst is:

fburst =

Wtot
pz;d

(25.7)

where:

pz;d is the upward water pressure, in kN/m2 , see Equation 25.11.
Wtot is the total weight above the aquifer, in kN/m2 , see Equation 25.8;
Total weight above the aquifer

Wtot = Wtot;1 + Wtot;2
Wtot;1 = f × γ1;d × d1;d
n
X
Wtot;2 =
γj;d × dj;d

(25.8)
(25.9)
(25.10)

j=1

with:

2
f=
π

d2;d
d2;d
b
b
1+
× arctan
− × arctan
a
a+b
a
b

where:

a
b
d1;d
d2;d
f
Wtot;1
Wtot;2
γ1;d

is the width (horizontally) of the slope of the trench, in m;
is the depth of the slope of the trench, in m;
is the sum of the thickness of the layers above the excavation level, in m;
is the sum of the thickness of the layers below the pipe (excavation level) and
above the aquifer, in m.
is the factor for the contribution of the layers above the excavation level according
to Figure 25.2;
is the weight of the soil layers above the trench bottom, in kN/m2 ;
is the weight of the overburden soil layers below the trench bottom, in kN/m2 ;
is the average unit weight of the layers above the excavation level, in kN/m3 ;

Upward water pressure

pz;d = Hd × γw

(25.11)

where:

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Hd
γw

is the hydraulic head with respect to the upper boundary of the aquifer, calculated
according to section 26.1;
is the unit weight of water, in kN/m3 .

Figure 25.1: Definition of parameters Hd , d1;d and d2;d (Figure 18 of NEN 6740:2006)

Figure 25.2: Factor f for the contribution of the layers above the bottom of the excavation
(Figure 19 of NEN 6740:2006)

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26 Effective Stress and Pore Pressure
26.1

Hydraulic head from piezometric level lines
A piezometric level line (PL-line) represents the initial and transient hydraulic water heads in
the soil, excluding the excess component. Several PL-lines can be defined in the PL-Lines
window (section 4.3.10). A PL-line for the top and bottom of each soil layer can be defined in
the Pl-lines per Layer window (section 4.3.13).

PL-line 2
PL-line 1

SAND
CLAY

1
2

99
99

SAND
CLAY2

2
2
1
1

99
99
99
2

SAND

Figure 26.1: Pore pressure as a result of piezometric level lines

D-G EO P IPELINE calculates the hydraulic pore pressure along a vertical in the following way:
The pore pressure inside a layer is calculated by linear interpolation between the pore pressures at the top and bottom. The pore pressure at the top or bottom is equal to the vertical
distance between this point and the position of the PL-line that belongs to this layer, multiplied
by the unit weight of water.
If PL-line number 99 is specified for the top and/or bottom of any soil layer, at that boundary
D-G EO P IPELINE will use the PL-line of the nearest soil layer above or below, which has a
thickness larger than zero and a PL-line number not equal to 99. If the interpolation point
is located above the phreatic line, the pore pressure is assumed to be zero or a capillary
pressure, depending on the sign of the PL-line number. The following options are available,
therefore, for PL-line numbers:

Positive integer:
Capillary pore pressures are not used – that is, if negative pore pressures are calculated
for points above the phreatic line they become zero;

Zero:
All points within the layer obtain a pore pressure of 0 kN/m;

99:
The pore pressure depends on the first layer above and/or below the point with a PL-line

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number unequal to 99.
26.2

Phreatic line
The phreatic line (or groundwater level) marks the border between dry and wet soil. The
phreatic line is treated as if it was a PL-line, and can also be used as such. The PL-line acting
as the phreatic line is determined while the geometry is being defined. If no phreatic line is
entered, then all the soil is assumed to be dry.

26.3

Stress by soil weight
The total stress at depth z due to soil weight is:

σsoil (z) =

γunsat × z
if z > zwater
γunsat × zwater + γsat × (zwater − z) if z ≤ zwater

(26.1)

where:

γunsat
γsat
z
zwater
26.4

is the unit weight of soil above phreatic level, in kN/m3 ;
is the unit weight of soil below phreatic level, in kN/m3 ;
is the vertical co-ordinate, in m;
is the vertical co-ordinate of the phreatic level, in m.

Distribution of stress by loading
D-G EO P IPELINE uses Boussinesq’s formula (Boussinesq, 1885) to determine the additional
vertical stress due to the surcharge loads.

26.4.1

Stress increment caused by a line load

Figure 26.2: Stress distribution under a load column

The vertical stress increment ∆σz due to a line load Q is:

∆σz =

2Q
cos4 φ
πz

(26.2)

where:

is the depth, in m;

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Q
φ
26.4.2

is the line load, in kN;
is the angle with the vertical, in radians.

Stress increment caused by a strip load
The stress increments in a point (x, y ) due to a strip load can be found by integration of the
line load along the width 2 dx of the strip load in Equation 26.2:

∆σload =

q
[(φ1 − φ2 ) + sin φ1 cos φ1 − sin φ2 cos φ2 ]
π

(26.3)

Figure 26.3: Stress distribution under a load column

26.5

Effective stress and pore pressure
The pore pressure u at vertical position z is defined as:

u (z) = σwater (z) − max [h (z) − z; 0] × γw

(26.4)

The effective stress σ ’ at vertical position z is defined as:

σ 0 (z) = σsoil (z) + ∆σload (z) − u (z)

(26.5)

with:

σwater (z) = max (zwater − zsurface ; 0) × γw
where:

z
zwater
zsurface
h
σsoil
σwater
∆σload

Deltares

is the vertical co-ordinate, in m;
is the vertical position of the phreatic level , in m;
is the vertical position of the ground level , in m;
is the user-defined hydraulic head in the Pl-lines per Layer window (section 4.3.13), see section 26.1;
is the stress due to soil weight, in kN/m2 , see Equation 26.1;
is the stress due to a water level above the soil surface, in kN/m2 ;
is the incremental stress due to loads, in kN/m2 , see Equation 26.3.

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27 Benchmarks
Deltares Systems commitment to quality control and quality assurance has leaded them to
develop a formal and extensive procedure to verify the correct working of all of their geotechnical engineering tools. An extensive range of benchmark checks have been developed to
check the correct functioning of each tool. During product development these checks are run
on a regular basis to verify the improved product. These benchmark checks are provided
in the following sections, to allow the user to overview the checking procedure and verify for
themselves the correct functioning of D-G EO P IPELINE. The benchmarks are subdivided into
five separate groups as described below.

Group 1 – Benchmarks from literature (exact solution) Simple benchmarks for which
an exact analytical result is available from literature.

Group 2 – Benchmarks from literature (approximate solution) More complex benchmarks described in literature for which an approximate solution is known.

Group 3 – Benchmarks from spread sheets Benchmarks which test program features
specific to D-G EO P IPELINE.

Group 4 – Benchmarks generated by D-G EO P IPELINE Benchmarks for which the reference results are generated using D-G EO P IPELINE.

Group 5 – Benchmarks compared with other programs Benchmarks for which the
results of D-G EO P IPELINE are compared with the results of other programs.

The number of benchmarks in group 1 may grow in the future. The benchmarks in this chapter
are well documented in literature. There are no exact solutions available for these problems,
however in the literature estimated results are available. When verifying the program, the
results should be close to the results found in the literature. The number of benchmarks
in group 2 will grow as new versions of the program are released. These benchmarks are
designed so that (new) features specific to the program can be verified. The benchmarks are
kept as simple as possible so that only one specific feature is verified from one benchmark
to the next. As much as software developers would wish they could, it is impossible to prove
the correctness of any non-trivial program. Re-calculating all the benchmarks, and making
sure the results are as they should be, proves to some degree that the program works as it
should. Nevertheless, there will always be combinations of input values that will cause the
program to crash or to produce wrong results. Hopefully by using the verification procedure
the number of ways this can occur will be limited. The benchmarks are all described in details
in the Verification Report available in the installation directory of the program.

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Bibliography
“SCIA Pipeline.” (integrated in the
online.com/en/pipeline-calculation.html.

program

Scia

Engineer)

http://www.scia-

Boussinesq, J., 1885. Application des Potentiels á l’Etude de l’Equilibre et du Mouvement des
Solides Elastiques. Gauthier-Villars, Paris.
Brinch Hansen, J., 1970. “A revised and extended formula for bearing capacity.” Lyngby
Bulletin No. 28. Danish Geotechnical Institute.
Broere, W., 1994. Tunnel face stability and new cpt applications. DUP Science. Delft.
Broms, B. B. and H. Bennermark, 1967. “Stability of clay at vertical openings.” American
Society of Civil Engineers, Journal of Soil Mechanics and Foundation Division pages 7195.
Davis, E. H., M. J. Gunn, R. J. Mair and H. N. Seneviratne, 1980. “The stability of shallow
tunnels and underground openings in cohesive material.” Geotechnique 30 pages 397-416.
Deltares. D-Settlement User Manual. Deltares Systems.
Deltares, 2004. WATEX Manual. Delft GeoSystems.
Jancesz, S. and W. Steiner, 1994. “Face support for a large mix shield in heterogeneous
ground conditions.” Proc conf. Tunnelling London.
Meijers, P. and R. A. J. de Kock, 1995. “A calculation method for earth pressure on directional
drilled pipelines.” Pipeline technology conference Ostend.
NEN, 2006. NEN 6740:2006. Geotechniek - TGB 1990 - Basiseisen en belastingen (Geotechnics - TGB 1990 - Basic requirements and loads), in Dutch.
NEN, 2012a. NEN 3650-1:2012. Eisen voor buisleidingsystemen - Deel 1: Algemene eisen
(Requirements for pipeline systems - Part 1: General requirements), in Dutch.
NEN, 2012b. NEN 3650-2:2012. Eisen voor buisleidingsystemen - Deel 2: Aanvullende eisen
voor leidingen van staal (Requirements for pipeline systems - Part 2: Additional specifications for steel pipelines), in Dutch.
NEN, 2012c. NEN 3650-3:2012. Eisen voor buisleidingsystemen - Deel 3: Aanvullende eisen
voor leidingen van kunststof (Requirements for pipeline systems - Part 3: Additional specifications for plastic pipelines), in Dutch.
NEN, 2012d. NEN 3651:2012. Aanvullende eisen voor buisleidingen in of nabij belangrijke waterstaatswerken (Additional requirements for pipelines in or nearby important public
works), in Dutch.
O’ Reilly, M. P. and B. M. New, 1982. “Settlements above tunnels in U.K. Ű their magnitude
and prediction.” Tunneling Š82 pages 173 - 181.
Terzaghi, K., 1943. Theoretical soil mechanics. John Wiley & Sons, Inc. New York.

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Deltares

PO Box 177
2600 MH Delft
Rotterdamseweg 185
2629 HD Delft
The Netherlands

+31 (0)88 335 81 88
sales@deltaressystems.nl
www.deltaressystems.nl

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