| As is commonly known, the stress-strain behaviour in some soils such as clays, frozen soils and ice is non-linear, irreversible, anisotropic and time-dependent. This thesis develops three types of models to describe (1) time-independent stress-strain behaviour in triaxial stress states (and general stress states); (2) time-dependent stress-strain behaviour in 1-D straining; and (3) time-dependent stress-strain behaviour in triaxial stress states (and general stress states).;A new Elastic Visco-Plastic (EVP) model is developed for time-dependent behaviour of soils in 1-D straining based mainly on Bjerrum's work. A number of important new concepts, such as "equivalent times", "reference time line", "instant time line" are introduced. A general ;Based on the work of hypoelasticity models and 1-D EVP models, a new framework of 3-D EVP models is developed. Some concepts such as "flow surfaces", "visco-plastic potential", "consistency conditions" and "evolution law" are used in the framework. Two 3-D flow functions are developed for initially isotropic and anisotropic soils. Non-linear strength envelopes may be incorporated in the flow functions. New scaling and calibration methods are proposed for the 3-D EVP models. Two specific models from the framework are constructed and applied to a sand-bentonite mixture and a frozen sand. The two models are calibrated using some tests and are verified using different tests.;Uncertainties and limitations of the three types of models are discussed. Suggestions for further development and refinement of these models are also presented in this thesis.;This thesis first presents a three-modulus hypoelasticity model for time-independent behaviour. Two new methods are suggested for determining the three moduli in the model using simple conventional triaxial tests. The model is calibrated for a sand-bentonite mixture and a medium-stiff plastic Paris clay using isotropic consolidation tests and CIU tests and for a medium dense Wuhan sand using isotropic consolidation tests and CID tests. The calibrated models are then used to predict the behaviour of the soils in different types of tests (constant-p... |
