Numerical simulation study on the thermal stress evolution and thermal cracking law of granite under heat conduction

In this study, a PFC2D model based on the XRD component distribution of the granite specimen was built by the discrete element method, and the model parameters were calibrated with reference to uniaxial compression tests. Subsequently, numerical simulations of the granite heat conduction, the evolution of thermal stress and thermal cracking characteristics, and the compressive failure of the heated specimen were completed with reference to the specimen heating process and the uniaxial compression test of the heated specimen. The simulation results show that the micro-parameters in the discrete model calibrated with k and b values could reflect the specimen deformation characteristic in the mechanical test. During heat conduction below 300 °C, the excursions of the stress tensor were insignificant, the abrupt changes of the stress ratio were little, the thermal cracks were less, and the uniaxial failure pattern of the heated specimen was similar to that at room temperature. Above 300 °C, the excursion of the stress tensor presented an apparent elliptical shape, with significant abrupt values of the stress ratio, and a greater amount of thermal cracking. The uniaxial failure pattern of the heated specimen exhibited clear end and edge failure.