Constitutive Simulation For The Volume Change Behaviour Of Unsaturated Soils Under Non-isothermal Conditions

Irreversible plastic deformation is easily happened in soils under the natural state, which is a kind of porous media made of loose particles. In many cases, the deformation is not only caused by the change of external load, and also closely related to the suction and the temperature. Especially in some special geotechnical engineering cases, the effect is particularly prominent. Such as construction of high level radioactive waste repositories, exploitation of natural gas hydrate and geothermal resources, heat-supply pipelines and high-voltage cables burial in city constructions. All those corresponding geotechnical material is influenced by external load, hydraulic and thermal interaction, which makes the deformation characteristics of soils more complicated.In order to understand the deformation of the soils under the coupled action of thermo-hydro-mechanical better, and carry on the quantitative description, this paper simulate the constitutive model considering temperature effect for unsaturated soils proposed by Cai Guoqing(2012). First of all, through studying extensive literature, this paper summarizes the influence of the temperature on basic properties of unsaturated soils, including test researches as well as relevant constitutive models. After the study of the summary of existing research results, we point out that the existing problems and the insufficiency, and offer reference for research work in this paper. Then in the basis of geotechnical elasticity-plasticity theories and the existing test results, this paper proposes a constitutive model of unsaturated soils under non-isothermal conditions by choosing appropriate stress variables, and establishes the corresponding yield condition, the law of hardening, the flow rule and the incremental constitutive equation. Finally, with a calculation program, the predictive ability of the model is realized and verified.The main research results include:(1) Based on the thermal-hydro-mechanical model, the effects of suction and temperature on deformation properties of unsaturated soils under the conditions of isotropic loading tests are forecasted and analyzed. In the light of the incremental constitutive equations of unsaturated soils considering the influence of temperature, we focus on the deformation parts and use Fortran language to compile the calculation programs and predict the deformation characteristics of unsaturated soils.(2) Based on the thermal-hydro-mechanical model, the effects of suction and temperature on deformation properties of unsaturated soil under the conditions of conventional shear tests are forecasted and analyzed. In the light of the incremental constitutive equations of unsaturated soils considering the influence of temperature, we focus on the deformation parts and use Fortran language to compile the calculation programs and predict the deformation characteristics of unsaturated soils.