Progressive Failure Process of Anisotropic Rock: Insight from Full-Field Strain Evolution
Yangyi Zhou, Xufeng Liu, Xifan Li
Abstract
Rocks with layered structure (bedding or foliation) usually exhibit different levels of anisotropy in terms of mechanical properties. The structural anisotropy has pronounced influence on the failure process of anisotropic rock. However, relatively few studies have been carried out on the subject. In this paper, the failure processes of a foliated gneiss with different schistosity orientations under uniaxial compression were studied based on digital speckle correlation method. The results show that the evolution process of full-field strain of the gneiss is closely related to the schistosity orientation. More specifically, when β = 0°, the strain concentration zone mainly originates from the microstructure, and the potential failure plane cannot be observed before total failure. When β = 30° or 60°, there are several strain concentration strips before failure. The ultimate failure is due to the interaction among these strips under the action of local stress field. When β = 90°, the initiation and evolution of strain concentration strip is relatively stable. When tensile failure occurs along the schistosity, the crack opens abruptly during loading. In contrast, the crack presents a gently stable growth trend, when the shear failure occurs along the schistosity.