Experimental and numerical investigations on mechanical properties and failure mechanism of flawed marble under triaxial compression

Flaws in rock masses have a critical effect on their strength and failure mode. Fewer studies have been conducted on the multi-parameter synergistic evolution of flawed marble specimens considering the confining pressure (σ3). Therefore, in this study, the mechanical behaviors and energy evolution of flawed marble specimens were investigated using triaxial compression experiments, and the crack propagation paths of flawed marble specimens were described using the discrete element method. The results indicate that as the flaw inclination angle (α) increases, the peak strength (σf) of the flawed marble initially decreases and then increases, reaching a minimum value between 45° < α < 60°. The percentage of elastic energy (Ue) did not change significantly as α increased, whereas the percentage of dissipated energy (Ud) decreased significantly when α > 45°. As σ3 increased, the failure mode of the marble changed from multiple tensile crack damage to single shear crack damage. The higher the σ3, the lower the number of cracks, and the crack propagated along the path closer to the direction of the minimum principal stress. The findings of this investigation are anticipated to enhance the understanding of the failure mechanisms of flawed rocks under triaxial compression.