Abstract: considering especially the influence of the thermal water diffusivity and the isothermal vapor diffusivity on the continuity of water and the energy balance, the author improved further the established control equations for analyzing coupled thermo-hydro- mechanical phenomena in saturated-unsaturated porous media. Using the experiment data of the buffer material and the 2D FEM code developed by the author, a numerical simulation for the coupled thermo-hydro-mechanical processes in near field of a conceptual nuclear waste repository in excavation and after closure is carried out; and the distributions and the changes of the displacements, plastic zones, principal stresses, pore pressures and temperatures in the surrounding rockmass are investigated. The computation results show that the excavation is the main reason for the displacements and redistributions of stress in surrounding rockmass of a cavern; and the coupled thermo-hydro-mechanical processes after the cavern closure also produce obvious influence on the displacements and stress states in the rockmass.

Key words: conceptual nuclear waste repository, excavation, closure, thermo-hydro-mechanical coupling, 2D finite element analysis