Study on Failure Process and Permeation Evolution of Single-Cracked Rock

To evaluate the mechanical properties and permeation evolution of cracked rock mass, failure evolution tests were designed by RFPA software for single-cracked rock mass with (i) different inclination angles under uniaxial compression and (ii) different confining pressures and pore pressures under triaxial compression. The results show the following: (1) Angle of the crack significantly affects the crack propagation mode and slightly affects the bearing capacity of rock. During the crack propagation, the peak of permeation is delayed at the peak of stress. The stress-strain curve shows a different behavior in the postcritical part of the curve, especially in the case of 45 degrees, where a smooth postcritical curve was clearly observed instead of an abrupt decrease in the stress of other two cases. (2) When the confining pressure is constant, the trend is almost the same when varying pore pressures, and with the increase in pore pressure, crack propagation is accelerated. At a low confining pressure, the crack is extended vertically to the upper and lower ends of the specimen, forming a longitudinal macroscopic crack. At a high confining pressure, the crack gradually extends to the left and right boundaries of the specimen, forming a transverse macroscopic crack. (3) The rate of crack initiation and destruction first decreases and then increases with the increase in confining pressure when pore pressure is constant.