Fracture behavior of cylindrical sandstone specimens with two pre-existing flaws: experimental investigation and PFC3D simulation

摘要

It is important to analyze the rock crack initiation, propagation and coalescence in fractured rock mass. At present, the 3D crack evolution process of pre-flawed rock has not been comprehensively studied during the deformation. In this study, uniaxial compression tests were carried out on cylindrical sandstone specimens with two pre-existing flaws with various ligament inclination angles. The crack evolution process at the front surface of the specimen was analyzed by photographic and AE monitoring. In addition, a 3D discrete element modelling was conducted to explore the spatial crack evolution behaviors during compressive loading. Both the numerical strength and final failure modes of specimens were consistent with those obtained in the laboratory experiment. The numerical simulation results revealed that the internal crack distribution was not always identical along the thickness direction. Two types of crack coalescence were identified. The experimental and numerical results enhance the understanding of 3D crack evolution mechanism of fractured rock under external loading.