Investigation of cross-interactions of coupled thermal-hydraulic-mechanical model using stochastic simulations

The fundamental study of coupled thermal–hydraulic-mechanical (THM) systems is an important issue in multi-physical fields. This study developed a THM model in which the hydraulic and mechanical effects are fully coupled and the temperature change serves as the perturbation source of the system. A porothermoelasticity model was applied to investigate the cross-interactions among the temperature, change in pore water pressure, and displacement of a buffer material in the near-field and a host rock in the far-field with the conceptual model in a nuclear waste repository. The results show that the size scale of the domain of interest and the THM properties play important roles in the coupled THM system. The changes in pore water pressure depended on the combined effect of the deformation of the porous space and pore water controlled by the thermal expansion coefficients of the solids and fluids. Stochastic analyses show that the uncertainties of variables varied spatio-temporally due to the thermal influences and approached zero due to the presence of a stable condition. The cross-interactions between displacement and change in pore water pressure induced by the thermal effect were complex and can be determined from statistical moment analyses.