Title Details

Laurence D. Wesley worked as a practicing geotechnical engineer for more than thirty years, with experience in New Zealand, Australia, Indonesia, Malaysia, and Bahrain. He is a Lifetime Member of the American Society of Civil Engineers, and a retired senior lecturer in geotechnical engineering at the University of Auckland.

Chapter 1 Fundamental Aspects of Residual Soil Behaviour.

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 Judgement.

1.7 Summary of Basic Differences between Residual and Sedimentary Soils.

References.

Chapter 2 Evaluation, Characterisation, 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.

Chapter 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.

Chapter 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 (allophone) soils.

4.3.5 Summary of Principal Aspects of Compression Behavior of Residual Soils.

4.4 Consolidation Behavior after Remoulding.

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 multi storey building on red clay.

4.8.2 Settlement estimate involving non-linear compressibility and pore pressure influence.

4.8.3 Significance of time rate assumption in the above 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.

References.

Chapter 5 Shear Strength of Residual Soils.

Introduction.

5.2 Undrained Shear Strength.

5.3 Effective Strength Properties.

5.3.1 Influence of discontinuities.

5.3.2 Correlation between Ø value and the Atterberg limits.

5.3.3 Effective strength parameters of a residual soil derived from shale.

5.3.4 Stress strain behaviour in triaxial tests.

5.3.5 The cohesion intercept c’.

5.3.6 Residual Strength.

References.

Chapter 6 Site Investigations and the Measurement of Soil Properties.

6.1 Introduction.

6.2 Approaches to Site Investigations.

6.3 Organisational 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.

6.5 Laboratory Testing.

6.5.1 Index or classification tests.

6.5.2 Tests on undisturbed samples.

6.5.3 "Computer errors" in processing laboratory test results.

6.6 Correlations with Other Properties and Parameters.

6.6.1 Undrained shear strength.

6.6.2 Relative density of sand.

References.

Chapter 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 (RE) construction.

References.

Chapter 8 Slope Stability and Slope Engineering.

8.1 Introduction.

8.2 Failure Modes.

8.3 The place of Analytical and Non-analytical 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.

8.9 Modelling 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.

Chapter 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 allophone 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 Behaviour.

9.2.12. Engineering projects involving allophone 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.

Chapter 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).

10.4 Laterites and tropical red clays (Group 5 in Figure 10.1).

10.5 Black, or "Black Cotton", Clays.

References.

Chapter 11 Compaction of Residual Soils.

11.1 Introduction.

11.2 Some reflections on compaction behaviour 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 Non-sensitive soils considerably wetter than optimum water content.

11.5.3 Sensitive highly structured soils.

11.6 Hard, partially weathered, residual soils.

References.