Geotechnical Problem Solving

Devised with a focus on problem solving, Geotechnical Problem Solving bridges the gap between geotechnical and soil mechanics material covered in university Civil Engineering courses and the advanced topics required for practicing Civil, Structural and Geotechnical engineers. By giving newly qualified engineers the information needed to apply their extensive theoretical knowledge, and informing more established practitioners of the latest developments, this book enables readers to consider how to confidently approach problems having thought through the various options available. Where various competing solutions are proposed, the author systematically leads through each option, weighing up the benefits and drawbacks of each, to ensure the reader can approach and solve real-world problems in a similar manner

The scope of material covered includes a range of geotechnical topics, such as soil classification, soil stresses and strength and soil self-weight settlement. Shallow and deep foundations are analyzed, including special articles on laterally loaded piles, retaining structures including MSE and Tieback walls, slope and trench stability for natural, cut and fill slopes, geotechnical uncertainty, and geotechnical LRFD (Load and Resistance Factor Design).

Preface vii

1 General Topics 1

1.1 How to Use This Book 2

1.2 You have to See It to Solve It 5

1.3 My Approach to Modern Geotechnical Engineering Practice – An Overview 12

1.4 Mistakes or Errors 26

2 Geotechnical Topics 35

2.1 Soil Classification – Why Do We Have It? 36

2.2 Soil Stresses and Strains 61

2.3 Soil Shear Strength 73

2.4 Shear Strength Testing – What is Wrong with the Direct Shear Test? 84

2.5 What is the Steady State Line? 94

2.6 Static Equilibrium and Limit States 105

2.7 Unsaturated Soils 110

3 Foundations 127

3.1 Settlements of Clays 128

3.2 Settlements of Sands 139

3.3 Self-Weight Settlement of Sandy Soils 161

3.4 Bearing Capacity of Shallow Foundations 169

3.5 Load Capacity of Deep Foundations 179

3.6 Laterally Loaded Piles and Shafts 205

4 Retaining Structures – Lateral Loads 221

4.1 Lateral Earth Pressure 222

4.2 Retaining Walls – Gravity, Cantilevered, MSE, Sheet Piles, and Soldier Piles 234

4.3 Tieback Walls 255

5 Geotechnical LRFD 267

5.1 Reliability, Uncertainty and Geo-Statistics 268

5.2 Geotechnical Load and Resistance Factor Design 278

5.3 LRFD Spread Footings 282

5.4 LRFD Pile Foundations 295

5.5 LRFD Drilled-Shaft Foundations 303

5.6 LRFD Slope Stability 312

6 Closing 321

6.1 The Big Picture 322

6.2 V and V and Balance 327

6.3 The Biggest Problem 330

6.4 Topics Left for Later 332

Index 335

Dr John Lommler is a practicing geotechnical engineer with 44 years experience in teaching, consulting and mentoring in Structural and Geotechnical Engineering. Dr Lommler is principal geotechnical engineer for AMEC in New Mexico and Texas. He began his career in Ohio in 1967 as a student structural engineer working on power plant projects. His career changed from structural to geotechnical engineering after studying under and mentoring received from Dr David Timmerman at the University of Akron.

Dr Lommler taught and practiced consulting geotechnical engineering in Ohio until 1991. When he moved to New Mexico to help his wife’s health, the move introduced him to arid, unsaturated, collapsible soils with Bob Booth and George Beckwith, which reinvigorated his career. In Albuquerque, he connected with Dr Ralph Peck, who inspired, mentored and encouraged him to continue geotechnical consulting practice past retirement age, mentor younger engineers, and write his book, Geotechnical Problem Solving.

Dr Lommler has written or co-authored over 1100 geotechnical reports and studies for commercial, municipal, state and federal government clients. He is author and co-author of several reports on Uranium Mill Tailings disposal cell design available from federal publishing sources, and is co-author of several geotechnical papers published in conference proceedings available from ASCE and the Geo-Institute.

This practical guide to advanced geotechnical topics helps readers solve problems in real-world situations.

Taking a personal tone and devised with a focus on practical aspects, Geotechnical Problem Solving bridges the gap between geotechnical and soil mechanics material covered in university Civil Engineering courses and the advanced topics required for practicing Civil, Structural and Geotechnical engineers. By giving newly qualified engineers the information needed to apply their extensive theoretical knowledge, and informing more established practitioners of the latest developments, this book helps readers confidently approach problems having thought through the various options available. Where various competing solutions are proposed, the author systematically guides readers through each option, weighing the benefits and drawbacks of each, to ensure they can approach and solve real-world problems in a similar manner.

• Links theoretical and practical work to provide a reference and guide to geotechnical topics
• Takes readers through various scenarios helping them to understand how to solve problems efficiently
• Provides a perspective on complexity in geotechnical practice
• Gives readers the tools they need to understand the principles and history behind the material so that they can handle real-world problems
• Covers a broad range of geotechnical topics, including soils, foundations and retaining structures, and provides an introduction to the background and application of geotechnical LRFD
• Reading recommendations are given including special articles and references for further study of advanced material
• Uses a ‘problem’ and ‘answer’ mentoring approach from the author to the reader to answer many of the reader’s questions