Abstract：For better understanding of thermo-hydro-mechanical coupling processes of argillite rock in Mont Terri project site during the long-time radioactive waste disposal，coupled fields of temperature，pore pressure and stress are studied during the heating and cooling phases with the theory of porous media mechanics. The anisotropy of thermo-hydro-mechanical behaviour is considered simultaneously during the calculation. The influence of the variation of water viscosity due to temperature variation on permeability of pore water is also considered during the simulation. The whole process of excavation，heating phase and cooling phase have been simulated in the calculation；and the calculated results are analyzed. It indicates that the anisotropy of thermo-hydro-mechanical behaviour of the argillite rock is the main factor affecting temperature distribution，pore pressure and stress fields. By comparing the simulated results of coupled isotropic model and anisotropy model，it is shown that the numerical results of coupled anisotropy model can objectively describe the coupled thermo-hydro-mechanical effect of the argillite rock located in the underground rock laboratory with thermal load. The simulation results also indicates that the argillite rock undertakes the compressive stress during the heating phase，while it undertakes tensile stress locally during the cooling phase；and these tensile stress maybe induce the generation of cracks in the rocks.
