Rock Crack Evolution and Acoustic Emission Characteristics Considering Crack Penetration Based on PFC

Different fracture penetrations exist widely in rock mass, but the research on penetration is rare at present. In order to study the deformation and failure behavior of rock mass with different fracture penetrations, triaxial compression tests were carried out on red sandstone with fracture penetrations of P=0%, 25%, 50%, 75%, and 100%, and PFC numerical simulation was conducted. The results show that: The greater the degree of fracture penetration, the smaller the strength of the rock sample, and the more obvious the plastic deformation section of the stress-strain curve. For intact rock samples, confining pressure will change the failure mode of rock samples, from tensile failure to shear failure. For fractured rock samples, the greater the penetration, the more complex the crack when the rock sample is destroyed. Under different confining pressures, the cracks of the same fractured rock sample are different when they are destroyed, but the overall failure type is unchanged. PFC^3D shows that when the complete rock sample is destroyed, the tensile crack first appears at the loading point, while the fractured rock sample first appears at the loading point and the prefabricated crack. Acoustic emission ringing count has a stationary period, a slow increase period, and a surge period. The macroscopic failure of the rock sample will occur in the strain-softening stage. The results in this paper can provide a basis for studying the fracture evolution law of rock mass in engineering.