Principles of Foundation Engineering, SI Seventh Edition

CONVERSION FACTORS FROM ENGLISH TO SI UNITS

Length: 1 ft

1 ft

1 ft

1 in.

1 in.

1 in.

Area:

Volume:

Force: 1 lb

1 lb

1 lb

1 kip

1 U.S. ton

1 lb

1 lb>ft

5 14.593 N>m

5 0.4536

3 1023 metric ton

5 8.896 kN

5 4.448 kN

5 0.4536 kgf

5 4.448

3 1023 kN

5 4.448 N

5 16.387 cm3 1 in3

5 16.387

3 1026 m3 1 in3

5 28.317

3 103 cm3 1 ft3

5 28.317

3 1023 m3 1 ft3

5 645.16 mm2 1 in2

5 6.452 cm2 1 in2

5 6.452

3 1024 m2 1 in2

5 929.03

3 102 mm2 1 ft2

5 929.03 cm2 1 ft2

5 929.03

3 1024 m2 1 ft2

5 25.4 mm

5 2.54 cm

5 0.0254 m

5 304.8 mm

5 30.48 cm

5 0.3048 m Stress:

Unit weight:

Moment: 1 lb-ft

1 lb-in.

Energy: 1 ft-lb

Moment of

inertia:

Section

modulus:

Hydraulic 1

conductivity: 1

1

1

1

1

1

1

Coefficient of

consolidation:

5 929.03 cm2 1 ft >sec 2

>sec

5 20.346

3 103 m2 1 in >yr 2

>sec

5 6.452 cm2 1 in >sec 2

>sec

in.>sec

5 25.4 mm>sec

in.>sec

5 2.54 cm>sec

in.>min

5 0.0254 m>min

ft>sec

5 304.8 mm>sec

ft>sec

5 0.3048 m>sec

ft>min

5 304.8 mm>min

ft>min

5 30.48 cm>min

ft>min

5 0.3048 m>min

5 0.16387

3 1024 m3 1 in3

5 0.16387

3 105 mm3 1 in3

5 0.4162

3 1026 m4 1 in4

5 0.4162

3 106 mm4 1 in4

5 1.3558 J

5 0.11298 N # m

5 1.3558 N # m

5 271.43 kN>m3 1 lb>in3

5 0.1572 kN>m3 1 lb>ft3

5 6.895 kN>m2 1 lb>in2

5 47.88 kN>m2 1 kip>ft2

5 95.76 kN>m2 1 U.S. ton>ft2

5 0.04788 kN>m2 1 lb>ft2

5 47.88 N>m2 1 lb>ft2

Principles of

Foundation Engineering, SI

Seventh Edition

BRAJA M. DAS

Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States

Principles of Foundation Engineering, SI

Seventh Edition

Author Braja M. Das

Publisher, Global Engineering:

Christopher M. Shortt

Senior Developmental Editor: Hilda Gowans

Editorial Assistant: Tanya Altieri

Team Assistant: Carly Rizzo

Marketing Manager: Lauren Betsos

Production Manager: Patricia M. Boies

Content Project Manager: Darrell Frye

Production Service: RPK Editorial Services, Inc.

Copyeditor: Shelly Gerger-Knecthl

Proofreader: Martha McMaster

Indexer: Braja M. Das

Compositor: Integra

Senior Art Director: Michelle Kunkler

Internal Designer: Carmela Pereira

Cover Designer: Andrew Adams

Cover Images:

Courtesy of ADSC : The International

Association of Foundation Drillers, Dallas, Texas

D. B. M. Contractors, Inc., Federal Way,

Washington

Image Permissions Researcher: Deanna Ettinger

Text Permissions Researcher: Katie Huha

Text and Image Permissions Researcher:

Kristiina Paul

First Print Buyer: Arethea Thomas

Printed in the United States of America

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©2011, 2007 Cengage Learning

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Library of Congress Control Number: 2010922634

ISBN-13: 978-0-495-66812-1

ISBN-10: 0-495-66812-5

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Contents

Preface xvii

1 Geotechnical Properties of Soil 1

1.1 Introduction 1

1.2 Grain-Size Distribution 2

1.3 Size Limits for Soils 5

1.4 Weight–Volume Relationships 5

1.5 Relative Density 10

1.6 Atterberg Limits 15

1.7 Liquidity Index 16

1.8 Activity 17

1.9 Soil Classification Systems 17

1.10 Hydraulic Conductivity of Soil 25

1.11 Steady-State Seepage 28

1.12 Effective Stress 30

1.13 Consolidation 32

1.14 Calculation of Primary Consolidation Settlement 37

1.15 Time Rate of Consolidation 38

1.16 Degree of Consolidation Under Ramp Loading 44

1.17 Shear Strength 47

1.18 Unconfined Compression Test 52

1.19 Comments on Friction Angle, 54

1.20 Correlations for Undrained Shear Strength, Cu 57

1.21 Sensitivity 57

Problems 58

References 62

fr

vii

viii Contents

2 Natural Soil Deposits and Subsoil Exploration 64

2.1 Introduction 64

Natural Soil Deposits 64

2.2 Soil Origin 64

2.3 Residual Soil 66

2.4 Gravity Transported Soil 67

2.5 Alluvial Deposits 68

2.6 Lacustrine Deposits 70

2.7 Glacial Deposits 70

2.8 Aeolian Soil Deposits 71

2.9 Organic Soil 73

2.10 Some Local Terms for Soils 73

Subsurface Exploration 74

2.11 Purpose of Subsurface Exploration 74

2.12 Subsurface Exploration Program 74

2.13 Exploratory Borings in the Field 77

2.14 Procedures for Sampling Soil 81

2.15 Split-Spoon Sampling 81

2.16 Sampling with a Scraper Bucket 89

2.17 Sampling with a Thin-Walled Tube 90

2.18 Sampling with a Piston Sampler 92

2.19 Observation of Water Tables 92

2.20 Vane Shear Test 94

2.21 Cone Penetration Test 98

2.22 Pressuremeter Test (PMT) 107

2.23 Dilatometer Test 110

2.24 Coring of Rocks 113

2.25 Preparation of Boring Logs 117

2.26 Geophysical Exploration 118

2.27 Subsoil Exploration Report 126

Problems 126

References 130

3 Shallow Foundations: Ultimate Bearing Capacity 133

3.1 Introduction 133

3.2 General Concept 133

3.3 Terzaghi’s Bearing Capacity Theory 136

3.4 Factor of Safety 140

Contents ix

3.5 Modification of Bearing Capacity Equations for Water Table 142

3.6 The General Bearing Capacity Equation 143

3.7 Case Studies on Ultimate Bearing Capacity 148

3.8 Effect of Soil Compressibility 153

3.9 Eccentrically Loaded Foundations 157

3.10 Ultimate Bearing Capacity under Eccentric Loading—One-Way

Eccentricity 159

3.11 Bearing Capacity—Two-way Eccentricity 165

3.12 Bearing Capacity of a Continuous Foundation Subjected to

Eccentric Inclined Loading 173

Problems 177

References 179

4 Ultimate Bearing Capacity of Shallow Foundations:

Special Cases 181

4.1 Introduction 181

4.2 Foundation Supported by a Soil with a Rigid Base at Shallow

Depth 181

4.3 Bearing Capacity of Layered Soils: Stronger Soil Underlain

by Weaker Soil 190

4.4 Bearing Capacity of Layered Soil: Weaker Soil Underlain

by Stronger Soil 198

4.5 Closely Spaced Foundations—Effect on Ultimate Bearing

Capacity 200

4.6 Bearing Capacity of Foundations on Top of a Slope 203

4.7 Seismic Bearing Capacity of a Foundation at the Edge

of a Granular Soil Slope 209

4.8 Bearing Capacity of Foundations on a Slope 210

4.9 Foundations on Rock 212

4.10 Uplift Capacity of Foundations 213

Problems 219

References 221

5 Shallow Foundations: Allowable Bearing Capacity

and Settlement 223

5.1 Introduction 223

Vertical Stress Increase in a Soil Mass Caused by Foundation Load 224

5.2 Stress Due to a Concentrated Load 224

x Contents

5.3 Stress Due to a Circularly Loaded Area 224

5.4 Stress below a Rectangular Area 226

5.5 Average Vertical Stress Increase Due to a Rectangularly

Loaded Area 232

5.6 Stress Increase under an Embankment 236

5.7 Westergaard’s Solution for Vertical Stress Due to a

Point Load 240

5.8 Stress Distribution for Westergaard Material 241

Elastic Settlement 243

5.9 Elastic Settlement of Foundations on Saturated Clay (S 0.5) 243

5.10 Settlement Based on the Theory of Elasticity 245

5.11 Improved Equation for Elastic Settlement 254

5.12 Settlement of Sandy Soil: Use of Strain Influence Factor 258

5.13 Settlement of Foundation on Sand Based on Standard Penetration

Resistance 263

5.14 Settlement in Granular Soil Based on Pressuremeter Test

(PMT) 267

Consolidation Settlement 273

5.15 Primary Consolidation Settlement Relationships 273

5.16 Three-Dimensional Effect on Primary Consolidation

Settlement 274

5.17 Settlement Due to Secondary Consolidation 278

5.18 Field Load Test 280

5.19 Presumptive Bearing Capacity 282

5.20 Tolerable Settlement of Buildings 283

Problems 285

References 288

6 Mat Foundations 291

6.1 Introduction 291

6.2 Combined Footings 291

6.3 Common Types of Mat Foundations 294

6.4 Bearing Capacity of Mat Foundations 296

6.5 Differential Settlement of Mats 299

6.6 Field Settlement Observations for Mat Foundations 300

6.7 Compensated Foundation 300

6.8 Structural Design of Mat Foundations 304

Problems 322

References 323

Contents xi

7 Lateral Earth Pressure 324

7.1 Introduction 324

7.2 Lateral Earth Pressure at Rest 325

Active Pressure 328

7.3 Rankine Active Earth Pressure 328

7.4 A Generalized Case for Rankine Active Pressure 334

7.5 Coulomb’s Active Earth Pressure 340

7.6 Active Earth Pressure Due to Surcharge 348

7.7 Active Earth Pressure for Earthquake Conditions 350

7.8 Active Pressure for Wall Rotation about the Top: Braced Cut 355

7.9 Active Earth Pressure for Translation of Retaining

Wall—Granular Backfill 357

Passive Pressure 360

7.10 Rankine Passive Earth Pressure 360

7.11 Rankine Passive Earth Pressure: Vertical Backface

and Inclined Backfill 363

7.12 Coulomb’s Passive Earth Pressure 365

7.13 Comments on the Failure Surface Assumption for Coulomb’s

Pressure Calculations 366

7.14 Passive Pressure under Earthquake Conditions 370

Problems 371

References 373

8 Retaining Walls 375

8.1 Introduction 375

Gravity and Cantilever Walls 377

8.2 Proportioning Retaining Walls 377

8.3 Application of Lateral Earth Pressure Theories to Design 378

8.4 Stability of Retaining Walls 380

8.5 Check for Overturning 382

8.6 Check for Sliding along the Base 384

8.7 Check for Bearing Capacity Failure 387

8.8 Construction Joints and Drainage from Backfill 396

8.9 Gravity Retaining-Wall Design for Earthquake Conditions 399

8.10 Comments on Design of Retaining Walls and a Case Study 402

Mechanically Stabilized Retaining Walls 405

8.11 Soil Reinforcement 405

xii Contents

8.12 Considerations in Soil Reinforcement 406

8.13 General Design Considerations 409

8.14 Retaining Walls with Metallic Strip Reinforcement 410

8.15 Step-by-Step-Design Procedure Using Metallic Strip

Reinforcement 417

8.16 Retaining Walls with Geotextile Reinforcement 422

8.17 Retaining Walls with Geogrid Reinforcement—General 428

8.18 Design Procedure fore Geogrid-Reinforced

Retaining Wall 428

Problems 433

References 435

9 Sheet Pile Walls 437

9.1 Introduction 437

9.2 Construction Methods 441

9.3 Cantilever Sheet Pile Walls 442

9.4 Cantilever Sheet Piling Penetrating Sandy Soils 442

9.5 Special Cases for Cantilever Walls Penetrating

a Sandy Soil 449

9.6 Cantilever Sheet Piling Penetrating Clay 452

9.7 Special Cases for Cantilever Walls Penetrating Clay 457

9.8 Anchored Sheet-Pile Walls 460

9.9 Free Earth Support Method for Penetration

of Sandy Soil 461

9.10 Design Charts for Free Earth Support Method (Penetration into

Sandy Soil) 465

9.11 Moment Reduction for Anchored Sheet-Pile Walls 469

9.12 Computational Pressure Diagram Method for Penetration into

Sandy Soil 472

9.13 Fixed Earth-Support Method for Penetration

into Sandy Soil 476

9.14 Field Observations for Anchor Sheet Pile Walls 479

9.15 Free Earth Support Method for Penetration of Clay 482

9.16 Anchors 486

9.17 Holding Capacity of Anchor Plates in Sand 488

9.18 Holding Capacity of Anchor Plates in Clay

( Condition) 495

9.19 Ultimate Resistance of Tiebacks 495

Problems 497

References 500

f 5 0

Contents xiii

10 Braced Cuts 501

10.1 Introduction 501

10.2 Pressure Envelope for Braced-Cut Design 502

10.3 Pressure Envelope for Cuts in Layered Soil 506

10.4 Design of Various Components of a Braced Cut 507

10.5 Case Studies of Braced Cuts 515

10.6 Bottom Heave of a Cut in Clay 520

10.7 Stability of the Bottom of a Cut in Sand 524

10.8 Lateral Yielding of Sheet Piles and Ground Settlement 529

Problems 531

References 533

11 Pile Foundations 535

11.1 Introduction 535

11.2 Types of Piles and Their Structural Characteristics 537

11.3 Estimating Pile Length 546

11.4 Installation of Piles 548

11.5 Load Transfer Mechanism 551

11.6 Equations for Estimating Pile Capacity 554

11.7 Meyerhof’s Method for Estimating Qp 557

11.8 Vesic’s Method for Estimating Qp 560

11.9 Coyle and Castello’s Method for Estimating Qp in Sand 563

11.10 Correlations for Calculating Qp with SPT

and CPT Results 567

11.11 Frictional Resistance (Qs) in Sand 568

11.12 Frictional (Skin) Resistance in Clay 575

11.13 Point Bearing Capacity of Piles Resting on Rock 579

11.14 Pile Load Tests 583

11.15 Elastic Settlement of Piles 588

11.16 Laterally Loaded Piles 591

11.17 Pile-Driving Formulas 606

11.18 Pile Capacity For Vibration-Driven Piles 611

11.19 Negative Skin Friction 613

Group Piles 617

11.20 Group Efficiency 617

11.21 Ultimate Capacity of Group Piles

in Saturated Clay 621

11.22 Elastic Settlement of Group Piles 624

11.23 Consolidation Settlement of Group Piles 626