3D finite element simulation for influence of thermo-hydro-mechanical coupling on migration in geological disposal of nuclear waste

A 2D model for coupling thermo-hydro-mechanical-migration and the relevant FEM code made by author is extended to 3D. From the viewpoint of methodology study, a 3D numerical simulation for the coupled thermo-hydro-mechanical-migratory processes in a simple model of geological disposal of nuclear waste, which is taken for example, is carried out. The distributions and changes of the temperature, saturation, nuclide concentration, pore pressure, displacement, normal stress and flow velocity in the near field are investigated. It is considered that the computation results are in keeping with the regular pattern. Finally, some conclusions are drawn: in order to simulate the migration of radioactive nuclide accurately, it is necessary to analyze temperature field, seepage field, stress field and nuclide concentration field by coupled method; higher compressive stresses will appear in the neighborhood of disposal pit wall after several decades from the embedment of nuclear waste; in buffer layer the period during which nuclide concentration reaches relative stabilization is much longer than those during which temperature and saturation reach relative stabilization respectively.