A Study on Mechanical Behavior of Intact Granite Through a Sound Simulation Using Flat-Jointed Contact

A series of laboratory tests were carried out focusing on the fracture characteristics of granite under different stress conditions. The macroscopic mechanical characteristics of granite, such as nonlinear stress–strain curve, tension compression bi-modularity, crack initiation, and propagation laws during Brazil splitting, were analyzed with the help of the digital image correlation method. A fine discrete-element model was established based on the laboratory test results and aimed to overcome the shortcomings of traditional simulation. The proposed model reproduced the characteristics of inherent microcrack closure, tension compression bi-modularity, and crack evolution under different stress paths. The detailed calibration method of the microparameters in the model was summarized. The relationship between macro-mechanical properties and micro-attributes of granite was further analyzed using the fine discrete-element model. The stress thresholds in uniaxial compression and crack initiation phenomenon in Brazil splitting were analyzed and explained from the micro-perspective. The microphysical significance of the Hoek–Brown criterion in shear failure was clarified through analyzing numerical test results. Hoek–Brown criterion is found being a statistical rule summary of the overall strength composed of the random distribution of the strength of the two parts in the rock: the cohesion of bonded particles and the friction of nonbonded particles.