Impact energy-absorption property of rock under tri-axial compression

By means of the improved SHPB with axial pre-pressure and confining pressure, a series of experiments on sandstone were carried out to investigate the energy consumption in rock fracturing during the course of deep underground resources exploitation. In the experiments, the cylindrical sandstone specimens were subjected to the static-dynamic coupling loads with fixed confining pressure or fixed axial static pressure. Under fixed confining pressures, the dynamic load energy densities consumed by the breakage of the sandstone specimens decrease gradually with the increase of axial static pressures. When the axial static stress is above 70% of the corresponding static tri-axial compressive strength, the dynamic load energy density consumed is below 0, namely, the sandstone specimens release energy. With the further increase of the axial static stress, the negative dynamic load energy density consumed approaches gradually to 0 and keeps below 0. If the axial static stress fixed is low, the dynamic load energy density consumed by the sandstone specimens increases continuously with the increase of the confining pressure. When the axial static stress fixed is great and above 70% of the corresponding static tri-axial compressive strength, the sandstone specimen can be fractured by itself and release the rest energy after losing the former balance by dynamic disturbance.