Thermo-hydro-mechanical response of granite to temperature changes

This paper examines the thermo-hydro-mechanical behaviour of a granitic rock. The cylindrical sample of granite contained a sealed fluid-filled cavity which was subjected to a cycle of temperature changes on its outer surface. The temperature and fluid pressure changes in the fluid-filled cavity were measured. Since the measurement of fluid pressure and temperature in the sealed cavity is experimentally feasible, the technique is a common feature in thermo-hydro-mechanical experiments. However, it was observed that regardless of how precisely the cavity was filled with de-aired water, air bubbles can still exist in the cavity and influence the fluid pressure changes. A novel technique is suggested for taking into account the influence of the volume of trapped air and eliminating its effect in the estimation of permeability. The experiment was computationally modelled using the finite element code COMSOL Multiphysics (TM) and the experimental results were compared with the computational estimates.