Volumetric deformation and damage evolution of Tibet interbedded skarn under multistage constant-amplitude-cyclic loading

Multistage constant-amplitude-cyclic (MCAC) loading experiments were conducted on Tibet interbedded skarn to investigate and characterize fatigue mechanical behavior of the tested rock. Rock volumetric deformation, stiffness change, and fatigue damage evolution were analyzed along with the macroscopic failure morphology. The experimental results demonstrated that the volumetric deformation of the tested skarn was influenced by the interbed structure. Rock damage presented a two-stage pattern. The rock damage increased quickly at the beginning and subsequently became steady for long periods of time within a cyclic loading stage. A new damage evolution model was proposed on the basis of axial strain. Macroscopic failure morphology analysis revealed different fracture mechanisms, combining a tension-splitting mode, shear-sliding, and mixed shear-tension. In this study, the understanding of the anisotropic mechanical properties of interbedded skarn was highlighted, and this could contribute to the ability to predict the stabilities of rock engineering structures.