Studies on coupled field of thermal response in rock mass of nuclear waste repository

The thermal and physical response of heated rock mass was the principal index to the safety evaluation of the nuclear waste repository. Combined with the in-situ measured results, the temperature, seepage and stress fields due to thermal load were analyzed by means of finite element method based on theory of mechanics of porous continuous medium. A nonlinear poro-elastic method was proposed during the calculation of thermal-hydro-mechanical coupling analysis. The main idea of this method was to adjust the permeability coefficient of the rock mass according to the changed porosity of rock mass. It was indicated with both the results of measurement and numerical simulation that the temperature and effective stresses in the rock mass increased with the development of heating time, while the pore pressure in rock mass increased at the beginning of variation of heating power and decreased in the end of the heating phase.