Craigs Soil Mechanics Eighth edition J. A. Knappett and R. F. Craig

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Craigs Soil Mechanics Eighth edition J. A. Knappett and R. F. Craig

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.