Peak strength, coalescence and failure processes of rock-like materials containing preexisting joints and circular holes under uniaxial compression: Experimental and numerical study

The stability of rock masses is greatly influenced by the voids and joints present in rock masses; therefore, the peak strength, coalescence and failure process of rock masses with preexisting joints and holes should be sys-tematically studied. To investigate the mechanical properties and failure mechanism of rock masses with circular holes and preexisting joints, rock-like materials were prepared, and uniaxial compression tests were performed. An analysis of physical test results showed that the coalescence patterns of rock bridges can be classified into 6 types, and the failure modes have 3 types. To further study the mechanical characteristics of rock-like materials with preexisting joints and circular holes, PFC2D numerical simulations were conducted, and the Bayesian optimization method was applied to obtain the microparameters of the PFC2D models. Through analysis of the numerical simulation results, it was concluded that the failure process of the specimen can be divided into four stages: stage I, stage II, stage III and stage IV. No cracks appeared in stage I, and few cracks appeared in stage III and stage IV. In stage IV, the specimen broke, and a large number of cracks appeared. These studies can serve as an experimental and numerical basis for the stability and fracture analysis of rock masses with preexisting joints and circular holes.