Post-peak deformation and failure behaviour of Jinping marble under true triaxial stresses

Abstract

The post-peak behaviour of rocks plays an important role in studying the stability of surrounding rocks. A series of true triaxial compression tests in high-low stress states were carried out on 58 Jinping marble specimens. The characteristics of complete stress–strain curves, including the post-peak stage, the corresponding meso- and micro-failure characteristics with scanning electron microscopy (SEM), and the whole progressive failure processes with acoustic emission (AE), were analysed. With either decreasing σ3 or increasing σ2, the shapes of the post-peak curves change from Class I to Transition and then to Class II. Additionally, the changes have obvious stress boundaries. As σ2 increases at low-constant σ3 or σ3 decreases at constant σ2, the failure mode changes from tensile–shear mixed failure or shear failure to tensile failure, and these changes correspond with the changes in the post-peak curves. Micro-failure of marble changes from intergranular failure at Class I to transgranular failure at Class II. The AE characteristics of the three typical post-peak progressive failure processes are significantly different, matching the brittle failure behaviour from weak to strong. This study enhances the knowledge of in situ failure mechanisms and the stability of deep-buried tunnels and caverns.