Unsaturated Soils - A Fundamental Interpretation Of Soil Behaviour

An understanding of the mechanical properties of unsaturated soils is crucial for geotechnical engineers worldwide, as well as to those concerned with the interaction of structures with the ground. This book deals principally with fine-grained clays and silts, or soils containing coarser sand and gravel particles but with a significant percentage of fines.
The study of unsaturated soil is a practical subject, linking fundamental science to nature. Soils in general are inherently variable and their behaviour is not easy to analyse or predict, and unsaturated soils raise the complexity to a higher level. Even amongst practicing engineers, there is often lack of awareness of the intricacies of the subject. This book offers a perspective of unsaturated soils based on recent research and demonstrates how this dovetails with the general discipline of soil mechanics.
Following an introduction to the basic soil variables, the phases, the phase interactions and the relevance of soil structure, an up-to-date review of laboratory testing techniques is presented. This includes suction measurement and control techniques in triaxial cell testing. This is followed by an introduction to stress state variables, critical state and theoretical models in unsaturated soils.
A detailed description of the thermodynamic principles as applied to multi-phase materials under equilibrium conditions follows. These principles are then used to explore and develop a fundamental theoretical basis for analysing unsaturated soils. Soil structure is broken down into its component parts to develop equations describing the dual stress regime. The critical state strength and compression characteristics of unsaturated soils are examined and it is shown how the behaviour may be viewed as a three-dimensional model in dimensionless stress-volume space. The analysis is then extended to the work input into unsaturated soils and the development of conjugate stress, volumetric and strain-increment variables. These are used to examine the micromechanical behaviour of kaolin specimens subjected to triaxial shear strength tests and lead to observations not detectable by other means.
Unsaturated Soils: A fundamental interpretation of soil behaviour covers a rapidly advancing area of study, research and engineering practice and offers a deeper appreciation of the key characteristics of unsaturated soil. It provides students and researchers with a framework for understanding soil behaviour and demonstrates how to interpret experimental strength and compression data.
provides engineers with a deeper appreciation of key characteristics of unsaturated soils
covers a rapidly advancing area of study, research and engineering practice
provides students and researchers a framework for understanding soil behaviour
shows how to interpret experimental data on strength and compression
the limited number of books on the subject are all out of date

Edward J. Murray is Director of Murray Rix Geotechnical, UK
Vinayagamoothy Sivakumar is Senior Lecturer at Queen's University Belfast, UK

"In a release, Research and Markets noted that report highlights include: An understanding of the mechanical properties of unsaturated soils is crucial for geotechnical engineers worldwide, as well as to those concerned with the interaction of structures with the ground." (TMCnet.com, 15 February 2011)
"This book offers a perspective of unsaturated soils based on recent research and demonstrates how this dovetails with the general discipline of soil mechanics." (AllVoices, 9 February 2011)

Preface.
Acknowledgements.
Introduction.
Symbols.
1 Properties of Unsaturated Soils.
1.1 Nature and genesis of unsaturated soils.
1.2 Soil variables.
1.3 Particle properties.
1.4 Phase properties and interactions.
1.5 Soil structure.
1.6 Experimental techniques for examining pore size distribution.
1.7 Pore size distribution.
1.8 Conclusions.
2 Suction Measurement and Control.
2.1 Introduction.
2.2 Techniques for measurement of suction.
2.3 Control of suction in laboratory tests.
2.4 Conclusions.
3 Laboratory Techniques.
3.1 Introduction.
3.2 Material selection and specimen preparation.
3.3 Experimental techniques for volume change and strength measurements.
3.4 Essential measurements.
3.5 Further details of triaxial and stress path testing techniques.
3.6 Conclusions.
4 Background to the Stresses, Strains, Strength, Volume Change and Modelling of Unsaturated Soil.
4.1 Introduction.
4.2 Stresses in soils.
4.3 Strains in soils.
4.4 Constitutive modelling.
4.5 Critical state framework for saturated soils.
4.6 The constitutive Barcelona Basic Model for unsaturated soils.
4.7 Extended constitutive and elasto-plastic critical state frameworks for unsaturated soils.
4.8 Concluding remarks.
5 Thermodynamics of Soil Systems.
5.1 Introduction.
5.2 Outline of thermodynamic principles and systems.
5.3 Introduction to equilibrium and meta-stable equilibrium.
5.4 Variables of state.
5.5 Extensive and intensive variables.
5.6 The laws of thermodynamics.
5.7 Thermodynamic potentials.
5.8 Thermodynamic potentials in practice.
5.9 Conjugate thermodynamic pairings.
5.10 Influence of a gravitational field.
5.11 Concluding remarks.
6 Equilibrium Analysis and Assumptions in Triaxial Testing.
6.1 Introduction.
6.2 The minimum principles for the potentials.
6.3 Isotropic loading conditions.
6.4 Anisotropic loading conditions.
6.5 Work input and the thermodynamic potential.
6.6 The thermodynamic potential and axis translation.
6.7 The thermodynamic potential and an aggregated soil structure.
6.8 Conclusions.
7 Enthalpy and Equilibrium Stress Conditions in Unsaturated Soils.
7.1 Introduction.
7.2 Role of enthalpy.
7.3 Enthalpy and Terzaghi's effective stress for saturated soils.
7.4 Enthalpy of unsaturated soils.
7.5 The significance of α.
7.6 Stress state in unsaturated soils.
7.7 Alternative equilibrium analysis.
7.8 Graphical representation of stress state in unsaturated soils.
7.9 Stress state variables and conjugate volumetric variables.
7.10 Hysteresis, collapse and discontinuities in soil behaviour.
7.11 Conclusions.
8 Shear Strength and Compression Characteristics of Unsaturated Soils.
8.1 Introduction.
8.2 Shear strength and critical state characteristics of unsaturated soils.
8.3 Equivalent strength parameters.
8.4 Compression and critical state characteristics of unsaturated kaolin.
8.5 Modelling of unsaturated kaolin.
8.6 Structure, variables and parameters.
8.7 Conclusions.
9 Work Input, Conjugate Variables and Load-Deformation Behaviour of Unsaturated Soils.
9.1 Introduction.
9.2 Work input under triaxial stress conditions.
9.3 Components of the deviator stress.
9.4 Work input to unsaturated soils.
9.5 Analysis of the mobilised stress ratios.
9.6 Continuity relationships between strain-increments.
9.7 Stress state variables and conjugate volumetric and strain-increment variables.
9.8 The meaning and interpretation of stresses and strains.
9.9 Analysis of triaxial experimental data on kaolin.
9.10 Conclusions.
References.
Index.