Simulation research on granite compression test based on particle discrete element model

Biaxial compression tests for granite in the underground caverns of Huangdao State Oil Reserves were virtually simulated using the bonded particle model (BPM) in particle flow code (PFC2D). The mesomechanical parameters corresponding to the macromechanical parameters of indoor compression tests were obtained through trial and error method. The simulated elastic modulus and Poisson's ratio show good agreement with the corresponding values of indoor compression tests. Due to the circle particle in BPM, cohesion and internal friction angle have some certain deviation compared with those of indoor compression tests. The simulated failure pattern of specimens is shear failure along single inclined plane, which agrees with the failure pattern of indoor compression tests. With the calibrated mesomechanical parameters, the microcrack development and energy dissipation of granite were further studied. The results show that there are three main stages during the microcrack development, i.e. stable development stage, rapid increase stage and stable development stage. The changing of boundary energy, strain energy, bond energy, frictional energy and kinetic energy has given an excellent explanation of the mesoscopic mechanics.