Creep of Soils And Other Related Phenomena

About this book

In this volume, soil creep is analysed within the framework of other soil-rheological phenomena, such as stress relaxation and long-term resistance, to present an in-depth discussion of the effect of time on soil behaviour. As time is the only state parameter which cannot be entirely modelled in the laboratory, the presented extrapolation is based upon a combination of appropriate theoretical analysis, and the principles of the physical behaviour of soils affected by state parameters such as porosity, water content, stress, strain, time and temperature. Principal macro- and microrheological theories are analysed, and a comprehensive picture of the soil structure and of the effect of state parameters is presented, documented by the author's experiments and illustrated by many examples. The theory of hereditary creep was selected as the best theory serving the author's purpose to propose simple constitutive relations governing creep of soils. The proposed constitutive relations have been implemented into FEM programs and the effect of the time factor has been demonstrated by the solution of such boundary value problems as a dams and underground tunnels.

Contents

1. Introduction. Macro- and microapproach. Aim of rheological investigations. Creep and the accuracy of its prediction. Limitations of rheological theories. Conception of this book. 2. Examples of the rheological behaviour of geomaterials. Settlement of structures. Dam displacements. Slope displacements. Conclusion. 3. Structure and texture of soils. Introduction. Mathematical and physical modelling of constitutive relations. Structural units. Fabric. Bonding. Internal stress. Structure of some tested soils: Zbraslav sand, Landstejn sand, Loess, Kyjice clay, Sedlec kaolin, &Dbreve;ablice claystone, Strahov claystone, Conclusion. Changes of soil structure. 4. State parameters of soils. Porosity. Water content. Stress and stress path. Strain. Time. Temperature. Conclusion. 5. Elasticity, viscosity and plasticity. Introduction. Elasticity. Viscosity. Plasticity: Introduction, Rigid-plastic approach, Modelling of constitutive behaviour, Plastic potential approach, Other physically motivated concepts, Rate-type relations. Concluding remarks. 6. Experimental rheology. Introduction. Water content and temperature fluctuations. Choice of the apparatus. Evaluation of the experimental results. 7. Macrorheology. Introduction. Method of rheological models. Method of integral representation. Empirical relations. 8. Microrheology. Introduction. Micromechanical approach. Particle-based conception: Fabric as the principal constitutive factor, Mixed analysis. 9. Primary and secondary consolidation. Introduction. Primary consolidation. Secondary consolidation. Conclusion. 10. Long-term strength of soils. Introduction. Stress - long-term strain diagrams. Long-term strength. Creep failure (rupture). Conclusion. 11. Creep and stress relaxation. Creep. Stress relaxation. Conclusion. 12. Numerical solution of rheological problems. Introduction. Numerical methods: Numerical methods in geomechanics, Finite-element method, Nonlinear techniques, Path-dependent constitutive model. Numerical modelling of creep: Review, Algorithms for computing creep by FEM. Applications: Dams, Tunnels. Conclusions. 13. Concluding comments. Appendix 1. Appendix 2. Bibliography. Author index. Subject index.

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