Applied Geotechnics for Construction Projects, Volume 3 Behavior and Design of Project Foundations and Eurocode Validation

Geotechnical engineering is now a fundamental component of construction projects. The third volume of this book is its backbone, dedicated to foundations for civil and industrial construction projects.

Applied Geotechnics for Construction Projects 3 first presents the basic theoretical principles and rules governing the designing and validation of foundations; shallow, semi-deep and deep, then presents real foundation projects with a detailed comparison of the approaches and methods of calculating foundations in relation to the reference systems and rules in force, closely compared to and validated by the Eurocodes. The third chapter presents examples of foundation projects, covering high-side building rafts, strip footings, piles and embankments, enriched by an unprecedented level of experience in the field of foundations for civil and industrial construction projects. It ends with examples of damage to foundations and practical appendices.

Each chapter of this third volume is illustrated with photographs and measurements of construction sites and is built on both theory and experience in the field of foundations as a whole. The result is a combination of geotechnical expertise and lessons learned from experience, both of which are highly valuable in the field of applied geotechnics for construction projects.

Ammar Dhouib, doctor of civil engineering specializing in soil mechanics, is a lecturer and professor of geotechnics at Polytech Sorbonne University, Paris, France. He is also a geotechnical expert at the VINCI construction group and a justice expert at the Court of Appeal in Versailles. His research interests focus on geotechnics, and he has authored or co authored five books on this topic.

Foreword ix
Philippe GUILLERMAIN† and François SCHLOSSER

Entrepreneur’s Tribune: Geotechnics is at the Heart of Our Projects xi
Pascal LEMOINE and Eric DURAND

Preface xiii

Acknowledgments xix

Symbols and Notations xxi

Introduction lv

Chapter 1 Foundations: Behavior, Design, and Justification 1

1.1 Analogies and differences between foundations 1

1.1.1 Foundations and their integration into the geotechnical project 1

1.1.2 Method of operation and similarities in behavior 3

1.1.3 Photos providing demonstrations of foundations 6

1.2 Shallow foundations 7

1.2.1 Types of shallow foundations 7

1.2.2 Behavior of a load-bearing footing 9

1.2.3 Load-bearing capacity of the subsoil 10

1.2.4 The special case of a footing under an eccentric load 22

1.2.5 Special cases of footings under an inclined load on horizontal ground 25

1.2.6 The special case of a footing on the crest of a slope 26

1.2.7 The case of a footing on two layers 29

1.2.8 The case of a footing on a dual layer: soft soil on top of a nearby substratum 30

1.2.9 Calculation of settlements under footings 31

1.2.10 Special cases: constructive provisions 38

1.3 Superficial foundations on rafts 40

1.3.1 Roles and types of rafts 40

1.3.2 Load-bearing capacity of soil under rafts 41

1.3.3 Settlements under rafts 41

1.4 Deep foundations 43

1.4.1 Preamble 43

1.4.2 Insulated pile under axial load 44

1.4.3 Isolated pile under lateral reactions 71

1.4.4 Effect of groups of piles 81

1.4.5 Justification of deep foundations 86

1.5 For the special case of foundation blocks subjected to reverse forces 93

1.5.1 The elastic center method 94

1.5.2 The rotation method 95

1.5.3 Simplified method 96

1.5.4 The “State Network” method 98

1.6 Consideration for other forces on the foundations 98

1.6.1 Spurious stresses due to soil swelling 98

1.6.2 Parasitic stress due to soil shrinkage 100

1.6.3 Seismic actions on piles: simplified Souloumiac method 100

1.6.4 The special case of vibrating machines on a non-deformable foundation block 102

1.7 Threshold displacements of the structure 103

1.7.1 Absolute settlements 103

1.7.2 Differential settlements (relative settlements) 104

Chapter 2 Real Projects and Comparisons of Methods and Referentials 109

2.1 Study of an apartment building on shallow footings 109

2.1.1 Project criteria 109

2.1.2 Soil data and foundation solution 110

2.1.3 Justification of the footings using the pressuremeter method 112

2.1.4 Justifications of the footings under the “Eurocodes” using the pressuremeter test (MPT) 113

2.1.5 Estimation of settlements (Ménard’s rule T0) 119

2.1.6 Comparison of calculation methods in terms of stresses 120

2.1.7 Impact of footing dimensions 129

2.1.8 Comparison of methods in terms of settlements 133

2.1.9 Determining the footing reaction coefficients 139

2.1.10 Footing stiffness 141

2.1.11 Practical rules for calculating the stiffness of footings 148

2.1.12 Reinforcement of footings 151

2.1.13 Economic analysis: do not just bury concrete for no reason! 153

2.2 Study of an office building on piles under axial loads 157

2.2.1 Project criteria 157

2.2.2 Soil data and foundation solution 158

2.2.3 Soil/pile interaction parameters and loads 159

2.2.4 Justification of the piles following the “Eurocodes” 160

2.2.5 Comparative study of the various regulations using the MPT method 173

2.2.6 Impact of the number of pile and soil tests (n) 177

2.2.7 Influence of the net limit pressure of the “MPT” method 180

2.2.8 Comparison of empirical methods of pile calculation 182

2.2.9 Axial stiffness of deep foundations 196

2.3 Horizontally loaded piles 202

2.3.1 Piles under parasitic horizontal pressure: application of the G(z) method 202

2.3.2 Analysis of pressures and moments using the “Tschebotarioff Method” 208

2.3.3 Evaluation of the negative friction on the piles 210

2.3.4 Rigidities at the top of horizontally stressed piles 212

2.4 Reinforcement of deep foundations 215

2.4.1 Reinforcement according to “static” standards 215

2.4.2 Reinforcement by “seismic” reference bases 218

2.5 Settlement of a general raft 226

2.5.1 Calculation of stresses and settlements 226

2.5.2 Reaction coefficient under raft 228

2.5.3 Reinforcement of the raft 233

2.6 Study of a road embankment on soft ground 235

2.6.1 Project 235

2.6.2 Data for the soil 236

2.6.3 Calculation of the bearing capacity of silty clays 239

2.6.4 Estimation of soil settlement under the embankment 240

2.6.5 Time of consolidation settlements 240

Chapter 3 Observations from Experience, Illustrative Examples, and Practical Appendices 243

3.1 The case of rafts in high-rise buildings 243

3.2 The case of strip footings 248

3.3 Behavior of piles under an axial load 250

3.4 Embankment settlement: Asaoka’s method (1978) 251

3.5 Summary and useful information 253

3.6 What not to do! 258

3.6.1 Early 1990s: metal piles driven into chalk 258

3.6.2 2010: poorly anchored piles in compact marls 259

3.6.3 2008: substrate misidentified via cone penetration test 259

3.6.4 2011: inadequate soil survey for pile anchoring 260

3.6.5 Damage still not settled since late 2000: “collapsible soils” 261

3.7 Wise conclusion 264

3.8 Appendices 265

3.8.1 Appendix 1: combinations of loads 265

3.8.2 Appendix 2: diffusion of stresses as a function of depth 267

3.8.3 Appendix 3: foundation blocks subject to overturning – methods for resolution 283

3.8.4. Appendix 4: determination of the stress bulb at ultimate limit states (ULS) by the pressuremeter method according to Eurocode 7

(standard NF P94 261, normative Appendix D) 292

3.8.5 Appendix 5: calculation of footing stiffness 294

3.8.6 Appendix 6: calculation of pile rigidities 323

3.8.7 Appendix 7: bearing capacity of piles under a vertical load 335

3.8.8 Appendix 8: frost protection in France 337

3.8.9 Appendix 9: earthquake and soil liquefaction 339

References 361

French, European and ISO Standards in the Field of Geotechnics 369

Index 401

Summaries of Other Volumes 405

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