Macro- and Meso-failure Features and Energy Evolution of Granite Under Uniaxial Compression

In order to reveal the macro- and meso-failure characteristics and energy evolution of heterogeneous brittle rock under uniaxial compression, the mineral composition, content and grain morphology of granite were firstly observed by polarized light microscopy. Then uniaxial and Brazilian split tests and numerical simulations of granite specimens were conducted to obtain the mechanical properties, failure characteristics and energy evolution. And the failure characteristics of granite under uniaxial compression were analyzed from macro- and mesoscope. The results indicate that granite is a typical heterogeneous brittle rock, and its stress-strain curve under uniaxial compression has almost no yield stage. The specimen bursts abruptly when the stress reaches the peak, and there is no residual strength. The specimens show coupling failure of shear and tensile damage from macro-mesoscope, and the spatial distribution of the shear and tensile damage is different. The damages continuously propagate and connect to form macroscopic failure surface in a short time after peak stress. Granite stored great amount of energy before ultimate strength, which is the essential cause of rock burst. Once the axial stress reaches its peak, the elastic strain energy stored previously converts into the dissipated energy, making the micro cracks propagate and intersect rapidly. These cracks aggregate and penetrate continuously, forming the macroscopic fracture surface within a short time. More energy dissipates on the shear and slide along the fracture surfaces, resulting in the final brittle failure of the granite.