A review of fracture mechanic behaviors of rocks containing various defects

The existence of defects in a rock mass is a vital factor complicating the mechanical response of the rock mass under stress. The characteristics of defects control the rock mass’s mechanical behaviors. This report reviews the experimental studies on the influence of simulating the internal defects of rock mass’s mechanical properties. The effects of preexisting defects (shape, size, number, angle, and other factors) on the mechanical properties and failure modes of the rock are investigated from the perspectives of rock failure and fracture mechanics. The fracture propagation mechanisms of different defective rock masses are analyzed by studying the stress state of different defective rock masses under uniaxial compression. After the defective rock samples with varying inclination angles are destroyed, the relationship among the compressive strength, the fracture propagation, and the failure characteristics is explored. The primary findings are as follows. The increase in the size and number of defects rapidly damages the mechanical properties of the rock and intensifies defect penetration and expansion. The rock mechanics characteristics of fissured rocks with different inclination angles show two primary variations: one is a continuous increase, and the other is a decrease followed by an increase. This result is strongly related to the failure pattern of rocks with preexisting fissures. This investigation is crucial for further studying the failure modes of complex defective rock masses and the geotechnical engineering related to defective rocks.