Numerical Simulation Study On Thermo-hydro-mechanical Coupling Process Of Unsaturated Soil

Numerical simulation of thermo-hydro-mechanical coupling of unsaturated soils has been a hot and difficult topic in geotechnical research and engineering because of its high subject comprehensivities and practical engineering application value.At present,there are mainly two ideas for the numerical simulation of a certain thermo-hydro-mechanical coupling problem: one is to use the interface of the existing relatively mature commercial software for secondary development,which can be solved by the powerful solver of commercial software,but is restricted by the input format of fixed formula;The other is to develop numerical programs,which are generally more difficult,but can be used to solve specific complex coupling problems.In this paper,numerical simulation work is carried out to solve the heat-water-force coupling problem of unsaturated soil.The main research results are as follows:(1)Established based on mild-manner singer with in the framework of effective stress of unsaturated soils considering the influences of temperature of thermo-hydro-mechanical coupled elastoplastic constitutive model,with the introduction of solid,liquid,gas phase mixture momentum,mass and energy conservation equation,ignore the influence of steam,established a consideration of the stress and strain,water seepage,gas transmission and coupling effect between heat transfer process of thermo-hydro-mechanical coupling model.Established by Galerkin method with displacement of soil skeleton and pore water pressure and pore air pressure and temperature for the unknown quantity of the finite element discrete equation,using backward euler difference method in discrete time domain,the control equation under control equation of the finite element calculation format,on the basis of based on C language developed can be used for the three dimensional finite element calculation program.(2)The application of finite element calculation program,establish a three dimensional numerical model of triaxial specimen in three-dimensional isotropic compression experiment simulated calculation,the experimental scheme based on Uchaipichat,first complete simulation of the temperature of the specimens-drying-load-unloading paths,a comprehensive inspection in the process of the simulation program cell temperature,saturation,and the correctness of the elastic-plastic deformation,on the basis of further validation process under the condition of different temperatures and different suction cell the correctness of the plastic deformation.(3)Based on the china-mock-up experiment,a 600-day numerical simulation was carried out on the thermo-hydro-mechanical coupling problem under the complex temperature and hydraulic boundary conditions,and the distribution variation rules of internal temperature,relative humidity,pore water pressure,saturation,expansion force and expansion deformation of the buffer material were analyzed under the condition of thermal-water-force coupling,and the simulation results and experimental results of the three main indexes of internal temperature,relative humidity and expansion force of the buffer material were compared and analyzed,which verified the effectiveness of the program in solving the temperature field,seepage field and deformation field under the condition of coupling.