Shear Mechanical and Permeability Properties of Deep Rock Mass under Thermal-Hydraulic-Mechanical Coupling

For the deep fractured rock mass, a variety of factors determine its mechanical properties, such as high in-situ stress, high seepage pressure and high temperature, etc. A series of shear experiments on saturated sandstone under different normal stress, seepage pressures were carried out, which had conducted five heat-water treatments. The setting max temperatures were 100, 300 and 400°C. The seepage pressure is constantly selected to be 5 MPa, while the normal stresses are 10, 15, and 20 MPa, respectively. The shear-seepage characteristics of sandstone under hydraulic-mechanical coupling were studied. The peak shear stress and its corresponding peak shear deformation increase with the increase of normal stress; with the increase of normal stress, the shear strength of specimen increases nearly nonlinearly. With the increase of temperature and water seepage pressure, the shear strength and the corresponding peak shear deformation will decrease. The weakening effect of seepage pressure on its shear mechanics was analysed. The study can provide a scientific theoretical basis for rock strength damage mechanism and disaster control under thermal-hydraulic-mechanical coupling in deep rock engineering.