The shearing anisotropy characteristics on the interface of loess with bedrock

The soil-bedrock interface is a common form of contact, which is widely distributed in various geological environments and involves many fields. Moreover, the stress history, geomaterial properties, and morphological differences of the soil-bedrock interface make it obvious regional characteristics, which greatly increases the complexity of the study. A series of laboratory direct shear experiments were carried out to study the anisotropic shear properties of loess-bedrock interface on the loess plateau in Shanxi Province, China. The results show that (1) the morphology of the shear plane is an important reason for the anisotropy of the loess-bedrock interface, which is mainly manifested by undulations. (2) The shear modes of the interface are mainly constituted by four forms: cutting, climbing, friction, and pushing, which together affect the anisotropy. (3) Based on the Mohr-Coulomb strength criterion, the influence of shear angle is considered, the expression of strength criterion for anisotropy of soil-rock interface and the strength envelope plane are obtained, which extends to three-dimensional state.