INTRODUCTION TO SOIL MECHANICS

Introduction to Soil Mechanics covers the basic principles of soil mechanics, illustrating why the properties of soil are important, the techniques used to understand and characterise soil behaviour and how that knowledge is then applied in construction. The authors have endeavoured to define and discuss the principles and concepts concisely, providing clear, detailed explanations, and a wellillustrated text with diagrams, charts, graphs and tables. With many practical, worked examples and end-of-chapter problems (with fully worked solutions available at www.wiley.com/go/bodo/soilmechanics) and coverage of Eurocode 7, Introduction to Soil Mechanics will be an ideal starting point for the study of soil mechanics and geotechnical engineering.

This book’s companion website is at
www.wiley.com/go/bodo/soilmechanics and offers invaluable resources for both students and lecturers:

• Supplementary problems
• Solutions to supplementary problems

 Béla Bodó B.Sc., B.A., C.Eng., M.I.C.E, was born in Hungary and studied at Budapest Technical University, the University of London and the Open University. He developed his expertise in Soil Mechanics during his employment with British Rail and British Coal.

 Colin Jones B.Sc, C. Eng., M.I.C.E, P.G.C.E, studied at the University of Dundee, and worked at British Coal where he and Béla were colleagues. He has recently retired from the University of Wales, Newport where he was Programme Director for the Civil Engineering provision, specializing in Soil Mechanics and Geotechnics.

Preface xii

Dedication and Acknowledgments xiii

List of Symbols xiv

1 Soil Structure 1

1.1 Volume relationships 1

1.2 Weight−volume relationships 6

1.3 Alteration of soil structure by compaction 20

1.4 California bearing ratio (CBR) test 30

1.5 The pycnometer 35

Supplementary problems for Chapter 1 39

2 Classification of Cohesive Soils 43

2.1 Atterberg Limits 43

2.2 Consistency indices 64

2.3 Classification of soils by particle size 69

Supplementary problems for Chapter 2 91

3 Permeability and Seepage 92

3.1 Coefficient of permeability (k) 93

3.2 Seepage velocity 94

3.3 Determination of the value of k 96

3.4 Field pumping tests 102

3.5 Permeability of stratified soil 107

3.6 Flow nets 108

3.7 Erosion due to seepage 121

3.8 Prevention of piping 128

3.9 Flow net for earth dams 129

Supplementary problems for Chapter 3 135

4 Pressure at Depth Due to Surface Loading 139

4.1 Concentrated point load 140

4.2 Concentrated line load 142

4.3 Uniform strip loading (Michell’s solution) 144

4.4 Bulb of pressure diagrams 147

4.5 Vertical pressure under triangular strip load 151

4.6 Vertical pressure under circular area 156

4.7 Rectangular footing 159

4.8 Footings of irregular shape 163

4.9 Pressure distribution under footings 167

4.10 Linear dispersion of pressure 170

Supplementary problems for Chapter 4 173

5 Effective Pressure 175

5.1 Unloaded state 175

5.2 Loaded state 177

5.3 Flooded state 180

5.4 Types of problem 182

5.5 Effect of seepage on shallow footings 194

5.6 Ground water lowering (at atmospheric pressure) 195

5.7 Reduction of artesian pressure 196

5.8 Capillary movement of water 199

Supplementary problems for Chapter 5 214

6 Shear Strength of Soils 219

6.1 Coulomb-Mohr Theory 220

6.2 Stress path 224

6.3 Effect of saturation 234

6.4 Measurement of shear strength 238

6.5 Thixotropy of clay 263

6.6 Undrained cohesion and overburden pressure 263

Supplementary problems for Chapter 6 265

7 Consolidation and Settlement 268

7.1 Consolidation 268

7.2 The pressure-voids ratio curve 270

7.3 Forms of the s'-e curve 279

7.4 Coefficient of compressibility 281

7.5 Coefficient of volume change 282

7.6 Estimation of settlement 284

7.7 Rate of consolidation 291

7.8 Pore pressure isochrones 301

7.9 Coefficient of permeability 310

7.10 Time from similarity 310

7.11 Total settlement 311

Supplementary problems for Chapter 7 314

8 Lateral Earth Pressure 319

8.1 Resistance to active expansion 320

8.2 The value of K0 321

8.3 Stress path representation 322

8.4 Rankine's theory of cohesionless soil 324

8.5 Rankine-Bell theory for c-f soil 334

8.6 Rankine-Bell theory for c-soil 336

8.7 Pressure-force and its line of action 336

8.8 Wall supporting sloping surface 342

8.9 General formulae for c-f soil 342

8.10 Formulae for pure clay (f =0) 349

8.11 Height of unsupported clay 350

8.12 Wedge theories 350

8.13 Stability of retaining walls 360

8.14 Sheet piles 368

8.15 Anchored sheet pile walls 375

8.16 Effect of ground water 393

8.17 Stability of deep trenches 400

8.18 Bentonite slurry support 406

Supplementary problems for Chapter 8 413

9 Bearing Capacity of Soils 420

9.1 Terminology 420

9.2 Shallow strip footing 424

9.3 Influence of footing shape 435

9.4 Shallow rectangular footing 436

9.5 Deep foundations 439

9.7 Pile Foundations 445

9.6 Standard penetration test (SPT) 443

9.8 Some reasons for choosing piles 449

9.9 Some reasons for not choosing piles 451

9.10 Effects necessitating caution 451

9.11 Negative skin friction 453

9.12 Stress distribution around piles 455

9.13 Load-carrying capacity of piles 455

9.14 End bearing resistance and SPT 464

9.15 Influence of pile section on Qu 465

9.16 Group of piles 465

Supplementary problems for Chapter 9 474

10 Stability of Slopes 479

10.1 Short-term and long-term stability 479

10.2 Total stress analysis (cohesive soils) 480

10.3 Effective stress analysis (cohesive soils) 513

10.4 Stability of infinite slopes 523

Supplementary problems for Chapter 10 528

11 Eurocode 7 530

11.1 Introduction 530

11.2 Recommended units 530

11.3 Limit states 531

11.4 Design procedures 531

11.5 Verification procedures 532

11.6 Application of partial factors 534

Appendices

Appendix A Mass and Weight 552

Appendix B Units, Conversion Factors and Unity Brackets 556

Appendix C Simpson's Rule 562

Appendix D Resultant Force and Its Eccentricity 567

Appendix E References 570

Index 572