Research on the Damage Constitutive Model and Fracture Behavior of Rocks Subjected to Uniaxial and Triaxial Compression

Under long-term geological processes, a large number of randomly distributed micro cracks formed within rocks. Due to external loads or disturbances from engineering excavation, the initiation, propagation, and coalescence of these micro cracks can lead to the degradation of the mechanical properties of the rock, thereby affecting the stability of the engineering structure. To establish a model that can describe the damage evolution characteristics of rocks under loading, a quantitative relationship between the damage element caused by the expansion of internal micro cracks and the overall damage of the rock is constructed based on the Weibull two-parameter model. By introducing damage variable into the Drucker-Prager (D-P) criterion, an elastoplastic damage model of rock is established, and the model is redeveloped by COMSOL. The model validity is verified through triaxial test results of rock under different confining pressures. Finally, the proposed model is used to investigate the fracture characteristics of rock with prefabricated cracks, the crack stress field, crack propagation path, and failure mode of rock under uniaxial test condition are analyzed.