Research progress on dynamic response of deep rocks under coupled hydraulic-mechanical loading

Deep rock is under a complex geological environment with high geo-stress, high osmotic pressure, and strong dynamic disturbance, under the action of the three, the rock body is more prone to damage and rupture, inducing sudden water surges, seepage, blowouts and other engineering geologic hazards. Therefore, investigating the rock dynamics of the rock under hydraulic-mechanical coupling is one of the prerequisites for conducting rock engineering construction. In recent years, many scholars have obtained some fruitful research results in the study of rock dynamics properties under the consideration of water and different stress states. In order to provide more comprehensive guidance for engineering construction and facilitate the subsequent research, the above work is reviewed and summarized in terms of experimental setups, test results, and the mechanism of the confining pressure and water content. Firstly, the basic principle of the split Hopkinson pressure bar (SHPB) system and the device improvements used to simulate the deep rock storage environment are introduced, including the confine-ment-coupled SHPB system and pore-pressure (osmotic pressure)-coupled SHPB system. The advantages and shortcomings of each type of device in the study of rock dynamics under hydraulic-mechanical coupling are briefly analyzed. Secondly, the dynamic mechanical response characteristics of rocks hydraulic-mechanical coupling considering different stress states (uniaxial confining, triaxial confining) are summarized. The dynamic mechanical response of deep rocks under fixed preset pore pressure and osmotic pressure coupling and its law of variation with pore water pressure and osmotic pressure are described in detail. Subsequently, the mechanism of confining pressure on the dynamic properties of the rock is outlined, and the influence law under different stress states is analyzed. The strengthening and weakening microscopic mechanism and quantitative expression of the dynamic mechanical properties of the rock by water are recapped. Finally, the dynamic response of deep rocks under hydraulic-mechanical coupling is summed up, and the further experimental research work and the research direction of deep rock dynamics are proposed.