Fundamentals of Soil Behavior

James K. Mitchell, ScD, is University Distinguished Professor Emeritus in Civil Engineering at the Virginia Polytechnic Institute and State University and Cahill Professor of Civil Engineering, Emeritus, University of California, Berkeley. He serves as a consultant on geotechnical problems and projects to many governmental and private organizations. He is an Honorary Member of the American Society of Civil Engineers and was elected to both the U.S. National Academy of Engineering and Academy of Sciences. Kenichi Soga, PhD, is Reader in Geomechanics. He has been on the faculty at the University of Cambridge, United Kingdom, since 1994. He is an editorial board member of Géotechnique, Journal of Geotechnical and Geoenvironmental Engineering, and Soils and Foundations. He also serves as a member of Engineering and Physical Sciences Research Council Peer Review College and a core member of the Technical Committee on Geotechnics of Particulate Media of the International Society for Soil Mechanics and Geotechnical Engineering.

Preface xi

CHAPTER 1 INTRODUCTION 1

1.1 Soil Behavior in Civil and Environmental Engineering 1

1.2 Scope and Organization 3

1.3 Getting Started 3

CHAPTER 2 SOIL FORMATION 5

2.1 Introduction 5

2.2 The Earth's Crust 5

2.3 Geologic Cycle and Geological Time 6

2.4 Rock and Mineral Stability 7

2.5 Weathering 8

2.6 Origin of Clay Minerals and Clay Genesis 15

2.7 Soil Profiles and Their Development 16

2.8 Sediment Erosion, Transport, and Deposition 18

2.9 Postdepositional Changes in Sediments 25

2.10 Concluding Comments 32

CHAPTER 3 SOIL MINERALOGY 35

3.1 Importance of Soil Mineralogy in Geotechnical Engineering 35

3.2 Atomic Structure 38

3.3 Interatomic Bonding 38

3.4 Secondary Bonds 39

3.5 Crystals and Their Properties 40

3.6 Crystal Notation 42

3.7 Factors Controlling Crystal Structures 44

3.8 Silicate Crystals 45

3.9 Surfaces 45

3.10 Gravel, Sand, and Silt Particles 48

3.11 Soil Minerals and Materials Formed by Biogenic and Geochemical Processes 49

3.12 Summary of Nonclay Mineral Characteristics 49

3.13 Structural Units of the Layer Silicates 49

3.14 Synthesis Pattern and Classification of the Clay Minerals 52

3.15 Intersheet and Interlayer Bonding in the Clay Minerals 55

3.16 The 11 Minerals 56

3.17 Smectite Minerals 59

3.18 Micalike Clay Minerals 62

3.19 Other Clay Minerals 64

3.20 Summary of Clay Mineral Characteristics 65

3.21 Determination of Soil Composition 65

3.22 X-ray Diffraction Analysis 70

3.23 Other Methods for Compositional Analysis 74

3.24 Quantitative Estimation of Soil Components 79

3.25 Concluding Comments 80

CHAPTER 4 SOIL COMPOSITION AND ENGINEERING PROPERTIES 83

4.1 Introduction 83

4.2 Approaches to the Study of Composition and Property Interrelationships 85

4.3 Engineering Properties of Granular Soils 85

4.4 Dominating Influence of the Clay Phase 94

4.5 Atterberg Limits 95

4.6 Activity 97

4.7 Influences of Exchangeable Cations and pH 97

4.8 Engineering Properties of Clay Minerals 98

4.9 Effects of Organic Matter 104

4.10 Concluding Comments 105

CHAPTER 5 SOIL FABRIC AND ITS MEASUREMENT 109

5.1 Introduction 109

5.2 Definitions of Fabrics and Fabric Elements 110

5.3 Single-Grain Fabrics 112

5.4 Contact Force Characterization Using Photoelasticity 119

5.5 Multigrain Fabrics 121

5.6 Voids and Their Distribution 122

5.7 Sample Acquisition and Preparation for Fabric Analysis 123

5.8 Methods for Fabric Study 127

5.9 Pore Size Distribution Analysis 135

5.10 Indirect Methods for Fabric Characterization 137

5.11 Concluding Comments 140

CHAPTER 6 SOIL-WATER-CHEMICAL INTERACTIONS 143

6.1 Introduction 143

6.2 Nature of Ice and Water 144

6.3 Influence of Dissolved Ions on Water 145

6.4 Mechanisms of Soil-Water Interaction 146

6.5 Structure and Properties of Adsorbed Water 146

6.6 Clay-Water-Electrolyte System 153

6.7 Ion Distributions in Clay-Water Systems 153

6.8 Elements of Double-Layer Theory 154

6.9 Influences of System Variables on the Double Layer 157

6.10 Limitations of the Gouy-Chapman Diffuse Double Layer Model 159

6.11 Energy and Force of Repulsion 163

6.12 Long-Range Attraction 164

6.13 Net Energy of Interaction 164

6.14 Cation Exchange--General Considerations 165

6.15 Theories for Ion Exchange 167

6.16 Soil-Inorganic Chemical Interactions 167

6.17 Clay-Organic Chemical Interactions 168

6.18 Concluding Comments 169

CHAPTER 7 EFFECTIVE, INTERGRANULAR, AND TOTAL STRESS 173

7.1 Introduction 173

7.2 Principle of Effective Stress 173

7.3 Force Distributions in a Particulate System 174

7.4 Interparticle Forces 174

7.5 Intergranular Pressure 178

7.6 Water Pressures and Potentials 180

7.7 Water Pressure Equilibrium in Soil 181

7.8 Measurement of Pore Pressures in Soils 183

7.9 Effective and Intergranular Pressure 184

7.10 Assessment of Terzaghi's Equation 185

7.11 Water-Air Interactions in Soils 188

7.12 Effective Stress in Unsaturated Soils 190

7.13 Concluding Comments 193

CHAPTER 8 SOIL DEPOSITS--THEIR FORMATION, STRUCTURE, GEOTECHNICAL PROPERTIES, AND STABILITY 195

8.1 Introduction 195

8.2 Structure Development 195

8.3 Residual Soils 200

8.4 Surficial Residual Soils and Taxonomy 205

8.5 Terrestrial Deposits 206

8.6 Mixed Continental and Marine Deposits 209

8.7 Marine Deposits 209

8.8 Chemical and Biological Deposits 212

8.9 Fabric, Structure, and Property Relationships: General Considerations 213

8.10 Soil Fabric and Property Anisotropy 217

8.11 Sand Fabric and Liquefaction 223

8.12 Sensitivity and Its Causes 226

8.13 Property Interrelationships in Sensitive Clays 235

8.14 Dispersive Clays 239

8.15 Slaking 243

8.16 Collapsing Soils and Swelling Soils 243

8.17 Hard Soils and Soft Rocks 245

8.18 Concluding Comments 245

CHAPTER 9 CONDUCTION PHENOMENA 251

9.1 Introduction 251

9.2 Flow Laws and Interrelationships 251

9.3 Hydraulic Conductivity 252

9.4 Flows Through Unsaturated Soils 262

9.5 Thermal Conductivity 265

9.6 Electrical Conductivity 267

9.7 Diffusion 272

9.8 Typical Ranges of Flow Parameters 274

9.9 Simultaneous Flows of Water, Current, and Salts Through Soil-Coupled Flows 274

9.10 Quantification of Coupled Flows 277

9.11 Simultaneous Flows of Water, Current, and Chemicals 279

9.12 Electrokinetic Phenomena 282

9.13 Transport Coefficients and the Importance of Coupled Flows 284

9.14 Compatibility--Effects of Chemical Flows on Properties 288

9.15 Electroosmosis 291

9.16 Electroosmosis Efficiency 294

9.17 Consolidation by Electroosmosis 298

9.18 Electrochemical Effects 303

9.19 Electrokinetic Remediation 305

9.20 Self-Potentials 305

9.21 Thermally Driven Moisture Flows 307

9.22 Ground Freezing 310

9.23 Concluding Comments 319

CHAPTER 10 VOLUME CHANGE BEHAVIOR 325

10.1 Introduction 325

10.2 General Volume Change Behavior of Soils 325

10.3 Preconsolidation Pressure 327

10.4 Factors Controlling Resistance to Volume Change 330

10.5 Physical Interactions in Volume Change 331

10.6 Fabric, Structure, and Volume Change 335

10.7 Osmotic Pressure and Water Adsorption Influences on Compression and Swelling 339

10.8 Influences of Mineralogical Detail in Soil Expansion 345

10.9 Consolidation 348

10.10 Secondary Compression 353

10.11 In Situ Horizontal Stress (K0) 355

10.12 Temperature-Volume Relationships 359

10.13 Concluding Comments 365

CHAPTER 11 STRENGTH AND DEFORMATION BEHAVIOR 369

11.1 Introduction 369

11.2 General Characteristics of Strength and Deformation 370

11.3 Fabric, Structure, and Strength 379

11.4 Friction Between Solid Surfaces 383

11.5 Frictional Behavior of Minerals 389

11.6 Physical Interactions Among Particles 393

11.7 Critical State: A Useful Reference Condition 400

11.8 Strength Parameters for Sands 404

11.9 Strength Parameters for Clays 411

11.10 Behavior After Peak and Strain Localization 415

11.11 Residual State and Residual Strength 417

11.12 Intermediate Stress Effects and Anisotropy 422

11.13 Resistance to Cyclic Loading and Liquefaction 425

11.14 Strength of Mixed Soils 432

11.15 Cohesion 436

11.16 Fracturing of Soils 438

11.17 Deformation Characteristics 444

11.18 Linear Elastic Stiffness 447

11.19 Transition from Elastic to Plastic States 452

11.20 Plastic Deformation 456

11.21 Temperature Effects 460

11.22 Concluding Comments 462

CHAPTER 12 TIME EFFECTS ON STRENGTH AND DEFORMATION 465

12.1 Introduction 465

12.2 General Characteristics 466

12.3 Time-Dependent Deformation-Structure Interaction 470

12.4 Soil Deformation as a Rate Process 478

12.5 Bonding, Effective Stresses, and Strength 481

12.6 Shearing Resistance as a Rate Process 488

12.7 Creep and Stress Relaxation 489

12.8 Rate Effects on Stress-Strain Relationships 497

12.9 Modeling of Stress-Strain-Time Behavior 503

12.10 Creep Rupture 508

12.11 Sand Aging Effects and Their Significance 511

12.12 Mechanical Processes of Aging 516

12.13 Chemical Processes of Aging 517

12.14 Concluding Comments 520

Questions and Problems 520

List of Symbols 523

References 531

Index 559