The density of groundwater in the surrounding rockmass of a geological disposal repository of high-level radioactive nuclear waste varies with the solute concentration

which will influence the thermo-hydro-mechanical processes in near field and far field of the saturated-unsaturated porous media. At the same time the temperature field and the stress field will also exert actions on the migratory of nuclides and solutes in groundwater. Considering these two factors the relevant momentum equilibrium equation

the continuity equation for water

the energy balance equation and the percolation and migration equation are established and introduced; and a 2D code of finite element method is developed for analyzing coupled thermo-hydro-mechanical-migratory phenomena in porous media. Through a numerical computation for the multi-field coupling progress after nuclide leakage in an assumed nuclear waste repository

the distribution and change of the temperature

stresses

pore pressures and nuclide concentrations in the near field are investigated. The results show that the established model and FEM code can be used to simulate coupled thermo-hydro- mechanical-migratory phenomena

so as to have certain practicality.