Study on energy concentration and dissipation of Beishan granite in Gansu during failure process

Servo test system was used to obtain stressstrain curves of Beishan granite under different confining pressure，and the loading process was jointly controlled by means of axial pressure and circumferential deformationVariation characteristics of energy and characteristic stress of Beishan granite were researchedCharacteristic stress are linear increase with confining pressure increasing，crack initiation stress，damage stress and peak strength increased 330 MPa，674 MPa，768 MPa respectively along with confining pressure increased 1 MPaTotal energy and elastic energy corresponding to characteristic stress are greatly increase with confining pressure increasingWhen confining pressure increased form 2 MPa to 30 MPa，elastic energy corresponding to initiation stress，damage stress and peak stress increased 52 times，58 times and 51 times respectively，corresponding total energy increased 49 times，57 times and 47 times respectivelyThe increment of dissipation energy increase with increasing of confining pressure，and energy at the crack unstable propagation stage was significant affected by confining pressureEnergy storage coefficient was defined to estimate rock stability around the peak strength，effect of stress state coefficient on energy storage was further analyzed