## Contents

List of figures xii

List of tables xxii

Preface xxiv

Part 1 Development of a mechanical model for soil 1

1 Basic characteristics of soils 3

Learning outcomes 3

1.1 The origin of soils 3

1.2 The nature of soils 6

1.3 Plasticity of fine-grained

soils 10

1.4 Particle size analysis 13

1.5 Soil description and classification 14

1.6 Phase relationships 22

1.7 Soil compaction 26

Summary 35

Problems 35

References 36

Further reading 37

2 Seepage 39

Learning outcomes 39

2.1 Soil water 39

2.2 Permeability and testing 41

2.3 Seepage theory 46

2.4 Flow nets 51

2.5 Anisotropic soil conditions 57

2.6 Non-homogeneous

soil conditions 59

2.7 Numerical solution using the Finite Difference Method 60

2.8 Transfer condition 63

2.9 Seepage through embankment dams 64

2.10 Filter design 73

Summary 74

Problems 74

References 77

Further reading 78

3 Effective stress 79

Learning outcomes 79

3.1 Introduction 79

3.2 The principle of effective stress 80

3.3 Numerical solution using the Finite Difference Method 83

3.4 Response of effective stress to a change in total stress 83

3.5 Effective stress in partially saturated soils 87

3.6 Influence of seepage on effective stress 87

3.7 Liquefaction 91

Summary 98

Problems 98

References 100

Further reading 100

4 Consolidation 101

Learning outcomes 101

4.1 Introduction 101

4.2 The oedometer test 102

4.3 Consolidation settlement 109

4.4 Degree of consolidation 112

4.5 Terzaghi’s theory of one-dimensional

consolidation 115

4.6 Determination of coefficient of consolidation 121

4.7 Secondary compression 126

4.8 Numerical solution using the Finite Difference Method 127

4.9 Correction for construction period 131

4.10 Vertical drains 136

4.11 Pre-loading 140

Summary 142

Problems 142

References 143

Further reading 144

5 Soil behaviour in shear 145

Learning outcomes 145

5.1 An introduction to continuum mechanics 145

5.2 Simple models of soil elasticity 149

5.3 Simple models of soil plasticity 152

5.4 Laboratory shear tests 156

5.5 Shear strength of coarse-grained

soils 168

5.6 Shear strength of saturated fine-grained

soils 174

5.7 The critical state framework 183

5.8 Residual strength 188

5.9 Estimating strength parameters from index tests 189

Summary 195

Problems 196

References 197

Further reading 199

6 Ground investigation 201

Learning outcomes 201

6.1 Introduction 201

6.2 Methods of intrusive investigation 203

6.3 Sampling 210

6.4 Selection of laboratory test method(s) 215

6.5 Borehole logs 216

6.6 Cone Penetration Testing (CPT) 218

6.7 Geophysical methods 222

6.8 Contaminated ground 227

Summary 228

References 229

Further reading 229

7 In-situ

testing 231

Learning outcomes 231

7.1 Introduction 231

7.2 Standard Penetration Test (SPT) 232

7.3 Field Vane Test (FVT) 236

7.4 Pressuremeter Test (PMT) 240

7.5 Cone Penetration Test (CPT) 252

7.6 Selection of in-situ

test method(s) 260

Summary 261

Problems 262

References 265

Further reading 266

Part 2 Applications in geotechnical engineering 267

8 Shallow foundations 269

Learning outcomes 269

8.1 Introduction 269

8.2 Bearing capacity and limit analysis 271

8.3 Bearing capacity in undrained materials 273

8.4 Bearing capacity in drained materials 285

8.5 Stresses beneath shallow foundations 295

8.6 Settlements from elastic theory 300

8.7 Settlements from consolidation theory 304

8.8 Settlement from in-situ

test data 311

8.9 Limit state design 316

Summary 323

Problems 324

References 325

Further reading 326

9 Deep foundations 327

Learning outcomes 327

9.1 Introduction 327

9.2 Pile resistance under compressive loads 331

9.3 Pile resistance from in-situ

test data 340

9.4 Settlement of piles 341

9.5 Piles under tensile loads 349

9.6 Load testing 350

9.7 Pile groups 353

9.8 Negative skin friction 358

Summary 359

Problems 359

References 361

Further reading 362

10 Advanced foundation topics 365

Learning outcomes 365

10.1 Introduction 365

10.2 Foundation systems 366

10.3 Shallow foundations under combined loading 380

10.4 Deep foundations under combined loading 389

Summary 398

Problems 399

References 400

Further reading 401

11 Retaining structures 403

Learning outcomes 403

11.1 Introduction 403

11.2 Limiting earth pressures from limit analysis 404

11.3 Earth pressure at rest 415

11.4 Gravity retaining structures 418

11.5 Coulomb’s theory of earth pressure 429

11.6 Backfilling and compaction-induced

earth pressures 434

11.7 Embedded walls 436

11.8 Ground anchorages 447

11.9 Braced excavations 452

11.10 Diaphragm walls 456

11.11 Reinforced soil 458

Summary 460

Problems 461

References 464

Further reading 465

12 Stability of self-supporting

soil masses 467

Learning outcomes 467

12.1 Introduction 467

12.2 Vertical cuttings and trenches 468

12.3 Slopes 472

12.4 Embankment dams 487

12.5 An introduction to tunnels 490

Summary 495

Problems 496

References 498

Further reading 499

13 Illustrative cases 501

Learning outcomes 501

13.1 Introduction 501

13.2 Selection of characteristic values 502

13.3 Field instrumentation 506

13.4 The observational method 514

13.5 Illustrative cases 515

Summary 517

References 517

Further reading 518

Principal symbols 519

Glossary 527

Index 543

## Preface

When I was approached by Taylor & Francis to write the new edition of Craig’s popular textbook, while

I was honoured to be asked, I never realised how much time and effort would be required to meet the

high standards set by the previous seven editions. Initially published in 1974, I felt that the time was

right for a major update as the book approaches its fortieth year, though I have tried to maintain the

clarity and depth of explanation which has been a core feature of previous editions.

All chapters have been updated, several extended, and new chapters added to reflect the demands of

today’s engineering students and courses. It is still intended primarily to serve the needs of the undergraduate

civil engineering student and act as a useful reference through the transition into engineering

practice. However, inclusion of some more advanced topics extends the scope of the book, making it

suitable to also accompany many post-graduate

level courses.

The key changes are as follows:

●● Separation of the material into two major sections: the first deals with basic concepts and theories

in soil mechanics, and the determination of the mechanical properties necessary for geotechnical

design, which forms the second part of the book.

●● Extensive electronic resources: including spreadsheet tools for advanced analysis, digital datasets

to accompany worked examples and problems, solutions to end-of-

chapter problems, weblinks,

instructor resources and more, all available through the Companion Website.

●● New chapter on in-situ

testing: focusing on the parameters that can be reliably determined using

each test and interpretation of mechanical properties from digital data based on real sites (which is

provided on the Companion Website).

●● New chapters on foundation behaviour and design: coverage of foundations is now split into three

separate sections (shallow foundations, deep foundations and advanced topics), for increased flexibility

in course design.

●● Limit state design (to Eurocode 7): The chapters on geotechnical design are discussed wholly

within a modern generic limit state design framework, rather than the out-dated

permissible stress

approach. More extensive background is provided on Eurocode 7, which is used in the numerical

examples and end-of-

chapter problems, to aid the transition from university to the design office.

●● Extended case studies (online): building on those in previous editions, but now including application

of the limit state design techniques in the book to these real-world

problems, to start to build

engineering judgement.

●● Inclusion of limit analysis techniques: With the increasing prevalence and popularity of advanced

computer software based on these techniques, I believe it is essential for students to leave university

with a basic understanding of the underlying theory to aid their future professional development.

This also provides a more rigorous background to the origin of bearing capacity factors and limit

pressures, missing from previous editions.

xxv

Preface

I am immensely grateful to my colleagues at the University of Dundee for allowing me the time to complete

this new edition, and for their constructive comments as it took shape. I would also like to express

my gratitude to all those at Taylor & Francis who have helped to make such a daunting task achievable,

and thank all those who have allowed reproduction of figures, data and images.

I hope that current and future generations of civil engineers will find this new edition as useful,

informative and inspiring as previous generations have found theirs.