5. Thermo-hydro-mechanical couplings

Rocks are porous and fissured media, and the various voids are often filled with one or more fluids. In the presence of a single fluid (water, for example), the medium is said to be saturated. These pore-filling fluids, also known as interstitial fluids, play a major role in rock behavior. Interstitial fluid pressures generate deformations, particularly elastic deformations, in rocks. Mechanical deformations, in turn, influence pore fluid pressures. There is thus a coupling between mechanical deformations and pore pressures - a hydromechanical coupling. Temperature variations also generate mechanical deformations, but mechanical deformations have little influence on rock temperatures. The coupling is therefore unidirectional. It should be added that other types of coupling may occur, involving chemical, biological or electrical phenomena for example, depending on the rock type. These couplings...