Dual-scale 3DEC-GBM Discrete Element Simulation On Mechanical Behavior and Anisotropic Fracture Evolution Mechanism of Rock Induced by True Three-dimensional Stress

The excavation of deep underground engineering causes a sophisticated three-dimensional stress redistribution in the surrounding rock, leading to the damage and rupture of the surrounding rock. It is difficult to reveal the fracture mechanism of rocks under complex stress loading path changes through conventional uniaxial or triaxial stress tests. In this study, a marble dual-scale 3DEC-GBM (grain-based modeling) discrete element model was established. The model was according to the practical mineral component of marble and its particle size distribution characteristics. Through laboratory true triaxial tests and numerical simulations, investigations were conducted on the deformation and strength characteristics of marble under true triaxial stress states. The evolution process and characteristics of anisotropic fracture and its microscopic tensile and shear fracture mechanism were also thoroughly investigated. Subsequently, the effects of intermediate principal stress σ₂ and minimum principal stress σ₃ on the intergranular and transgranular failures of marble as well as cracked anisotropy were analyzed, and the tensile–shear failure mechanism and crack anisotropy evolution law of the marble fracture evolution were determined under different true triaxial stress conditions. Finally, the effects of mineral crystal micromechanical parameters on the mechanical characteristics of marble under true triaxial conditions were examined.