Geotechnical engineering in residual soils / Laurence D. Wesley

Contents Preface and Acknowledgments 1 Fundamental aspects of Residual soil behavior 1.1 Introduction 1.2 Formation Processes and Basic Difference between Residual and Sedimentary Soils 1.3 Structure of Residual Soils 1.4 Special Clay Minerals 1.5 The Influence of Topography 1.6 Geotechnical Analysis, Design, and the Role of Observation and Judgment 1.7 Summary of Basic Differences between Residual and Sedimentary Soils References 2 Evaluation, Characterization, and Classification of Residual soils 2.1 Introduction 2.2 Parent Rock and the Soil Profile 2.3 Influence of Parent Rock on Geotechnical Properties 2.4 The Role of Observation 2.5 Standard Index Tests 2.5.1 Particle Size 2.5.2 Atterberg Limits 2.5.3 "Compactness" Indexes 2.6 Classification Systems for Residual Soils 2.6.1 Introduction 2.6.2 Methods Based on Pedological Groups 2.6.3 Methods Intended for Specific Local Use 2.6.4 A Grouping System Based on Mineralogy and Structure References 3 Pore Pressures and Seepage Conditions above and below the water table 3.1 Introduction 3.2 Situation at Level Sites 3.2.1 Static Case 3.2.2 Seasonal Effects 3.2.3 Coarse-Grained Soils 3.2.4 Low-Permeability Clays 3.2.5 Medium- to High-Permeability Clays 3.2.6 Use of Terzaghi Consolidation Theory to Illustrate Seasonal Influence 3.2.7 Field Records of Seasonal Effects 3.3 Hill Slopes, Seepage, and Pore Pressures 3.4 Permeability of Residual Soils 3.5 Significance of the Water Table (or Phreatic Surface) 3.6 Implications of the Groundwater and Seepage State above the Water Table for Practical Situations 3.6.1 Errors in the Estimation of Foundation Settlement Using Conventional Methods 3.6.2 Ground Settlement Resulting from Groundwater Lowering 3.6.3 Ground Settlement or Swelling Due to Covering the Ground Surface 3.6.4 Errors in Estimates of Slope Stability Ignoring Soil Suction Influence 3.6.5 Errors in Estimates of Slope Stability because of Simplified Assumptions Regarding the Seepage Pattern in the Slope References 4 Consolidation and Settlement 4.1 Introduction 4.2 Interpretation of Standard Oedometer Test Results and the "Omnipotence of Tradition" 4.3 Behavior of Residual Soils 4.3.1 Tropical Red Clay 4.3.2 Piedmont Residual Soil 4.3.3 Waitemata Residual Clay 4.3.4 Volcanic Ash (Allophane) Soils 4.3.5 Summary of Principal Aspects of Compression Behavior of Residual Soils 4.4 Consolidation Behavior after Remolding 4.5 Values of Stiffness Parameters for Residual Soils 4.6 Time Rate and Estimation of the Coefficient of Consolidation 4.7 Rate of Consolidation for Surface Foundations on Deep Soil Layers 4.8 Examples of Settlement Estimates 4.8.1 Foundations for a Multistory Building on Red Clay 4.8.2 Settlement Estimate Involving Nonlinear Compressibility and Pore Pressure Influence 4.8.3 Significance of Time Rate Assumption in the Previous Example 4.9 Accuracy of Settlement Estimates Based on Oedometer Tests 4.9.1 A Common Source of Error Arising from the Use of the Log Parameter (Cs) 4.9.2 Actual Settlement versus Predictions 4.10 Allowable Differential Settlement for Surface Foundations on Residual Soil References 5 Shear Strength of Residual Soils 5.1 Introduction 5.2 Undrained Shear Strength 5.3 Effective Strength Properties 5.3.1 Influence of Discontinuities 5.3.2 Correlation between φ Value and the Atterberg Limits 5.3.3 Effective Strength Parameters of a Residual Soil Derived from Shale 5.3.4 Stress---Strain Behavior in Triaxial Tests 5.3.5 The Cohesion Intercept c' 5.3.6 Residual Strength References 6 Site Investigations and the Measurement of soil properties 6.1 Introduction 6.2 Approaches to Site Investigations 6.3 Organizational and Administrative Arrangements 6.4 Planning Site Investigations 6.5 Field Work 6.5.1 Hand Auger Boreholes 6.5.2 Machine Boreholes 6.5.3 Penetrometer Testing 6.6 Block Sampling 6.7 In Situ Shear Tests 6.8 Laboratory Testing 6.8.1 Index or Classification Tests 6.8.2 Tests on Undisturbed Samples 6.8.3 "Computer Errors" in Processing Laboratory Test Results 6.9 Correlations with Other Properties and Parameters 6.9.1 Undrained Shear Strength 6.9.2 Relative Density of Sand References 7 Bearing Capacity and Earth Pressures 7.1 Introduction 7.2 Bearing Capacity and Foundation Design 7.3 Earth Pressure and Retaining Wall Design 7.3.1 Earth Pressure to Retain Cuts in Steep Slopes 7.3.2 The Use of Residual Soils for Reinforced Earth Construction References 8 Slope Stability and Slope Engineering 8.1 Introduction 8.2 Failure Modes 8.3 The Place of Analytical and Nonanalytical Methods for Assessing the Stability of Natural Slopes 8.4 Application and Limitations of Analytical Methods 8.5 Uncertainties in Material Properties 8.5.1 Slopes Consisting of Uniform, Homogeneous Materials 8.5.2 Slopes Containing Distinct, Continuous Planes of Weakness 8.5.3 Slopes of Heterogeneous Material, but without Distinct Planes of Weakness 8.6 Uncertainties in the Seepage and Pore Pressure State 8.6.1 Influence of Climate and Weather 8.6.2 Response of Seepage State and Pore Pressure to Rainfall 8.6.3 Comparison with Sedimentary Soils 8.7 The Worst-Case Assumption Regarding the Water Table 8.8 Transient Analysis of Rainfall Influence on the Stability of a Homogeneous Clay Slope 8.9 Modeling Stability Changes Resulting from Varying Rainfall Intensities 8.10 The Hong Kong Situation 8.10.1 Measurements of Pore Pressure Response 8.10.2 The Wetting Front Method for Estimating Water Table Rise 8.10.3 Importance of Antecedent Rainfall 8.10.4 Results of Stability Analysis and Assumptions Regarding the Pore Pressure State 8.10.5 Recommended Safety Factors for Hong Kong Slopes 8.10.6 Triaxial Tests and Back-Analysis of Landslides 8.10.7 Concluding Remarks on the Hong Kong Situation 8.11 Back-Analysis Methods to Determine Soil Parameters 8.11.1 Back-Analysis of a Single Slip or a Single Intact Slope 8.11.2 Analysis of a Number of Slips in the Same Material 8.11.3 Analysis of a Large Number of Intact Slopes (No Previous Slips) 8.12 Slope Design 8.12.1 Selection of the Profile for a New Cut Slope 8.12.2 To Bench or Not to Bench a Slope? 8.12.3 A Note on Vegetation Cover on Slopes References 9 Volcanic soils 9.1 Introduction and General Observations 9.2 Allophane Clays 9.2.1 Performance of Natural Hill and Mountain Slopes 9.2.2 Formation of Allophane Clays 9.2.3 Structure of Allophane Clays 9.2.4 Particle Size 9.2.5 Natural Water Content, Void Ratio, and Atterberg Limits 9.2.6 Influence of Drying 9.2.7 Degree of Saturation, Liquidity Index, and Sensitivity 9.2.8 Identification of Allophane Clays 9.2.9 Compressibility and Consolidation Characteristics 9.2.10 Strength Characteristics 9.2.11 Compaction Behavior 9.2.12 Engineering Projects Involving Allophane Clays 9.3 Volcanic Ash Clays Derived from Rhyolitic Parent Material 9.4 Other Unusual Clays of Volcanic Origin 9.5 Pumiceous Materials 9.5.1 Pumice Sands 9.5.2 Pumiceous Silts and Gravels References 10 Residual soils not Derived from Volcanic Material 10.1 Introduction 10.2 Weathered Granite (Group 1 in Figure 10.1) 10.3 Weathered Sedimentary Rocks 10.3.1 Soft Rocks---Sandstones, Mudstones, and Shale (Group 3 in Figure 10.1) 10.3.2 Hard Sedimentary Rocks (Group 4 in Figure 10.1) 10.4 Laterites and Tropical Red Clays (Group 5 in Figure 10.1) 10.5 Black or Black Cotton Clays References 11 Compaction of Residual Soils 11.1 Introduction 11.2 Some Reflections on Compaction Behavior of Soils and Quality Control Methods 11.3 Optimum Compactive Effort as well as Optimum Water Content 11.4 Alternative Compaction Control Based on Undrained Shear Strength and Air Voids 11.5 The Use of Shear Strength to

Overcome Difficulties in Compacting Residual Soils 11.5.1 Soils That Contain Wide and Random Variations in Properties 11.5.2 Nonsensitive Soils Considerably Wetter than Optimum Water Content 11.5.3 Sensitive, Highly Structured Soils 11.6 Hard, Partially Weathered, Residual Soils References Index

"Wiley has long held a pre-eminent position as a publisher of books on geotechnical engineering, with a particular strength in soil behavior and soil mechanics, at both the academic and professional level. This reference will be the first book focused entirely on the unique engineering properties of residual soil. Given the predominance of residual soils in the under-developed parts of the United States and the Southern Hemisphere, and the increasing rate of new construction in these regions, the understanding of residual soils is expected to increase in importance in the coming years. This book will be written for the practicing geotechnical engineer working to any degree with residual soils. It will describe the unique properties of residual soil and provide innovative design techniques for building on it safely. The author will draw on his 30 years of practical experience as a practicing geotechnical engineer, imbuing the work with real world examples and practice problems influenced by his work in South America and Southeast Asia"-- Provided by publisher

Includes bibliographical references and index