Static-dynamic coupling strength and deformation characteristics of rock under triaxial compression

By means of the improved SHPB with axial pre-pressure and confined pressure, a series of experiments on sandstone are carried out to research the mechanical behaviors of rock during the course of exploitation of resources in deep. The experiment includes some tests under triaxial static-dynamic coupling loads with fixed confined pressure or fixed axial static pressure. The results from tests under fixed confined pressure show that both static-dynamic coupling strength and elastic modulus are increased at the elastic stage and decreased at failure stage with increasing axial static pressure. The maximal strain rate and average strain rate are decreased at the elastic stage and increased at failure stage. When the axial static stress reaches to 80% of the corresponding static triaxial compressive strength, the static-dynamic coupling strength will be up to the maximum. On the condition of fixed axial static pressure, the static-dynamic coupling strength and elastic modulus are increased and the average strain rate is decreased with increasing confined pressure. It is found that the maximal strain rate is not obvious related with the confined pressure.