Undrained heating of geomaterials: Pore pressure increase and chemical couplings

Temperature increase in saturated porous materials under undrained conditions leads to volume change, pore fluid pressure increase and eventually chemical reactions of mineral decomposition. The increase in the pore fluid pressure induces a reduction of the effective mean stress and can lead to shear failure or hydraulic fracturing. In this paper, we present experimental results on the thermal pressurization of various geomaterials and cementitious materials. On the basis of the experimental results, a theoretical model which incorporates fluid production due to mineral decomposition and porosity production as source terms in the mass balance equation of the pore fluid is proposed to analyze the generation of pore pressure excess during rapid shear.