Study on the influence of non-bedding fissures on the instability and failure of anti-dip bedding rock slopes

Abstract

Non-bedding fissures are common internal defects in layered slopes and often exert control over the slope's stability. In this study, a research on the failure mechanism of anti-dip bedding rock slopes (ABRSs) with two sets of non-bedding fissures was conducted based on fracture mechanics theory and the ABRSs cantilever beam model. Through centrifuge test, the rationality of this calculation method was verified, and the instability evolution mechanism of anti-dip bedding rock slopes containing internal defects was investigated. The research findings demonstrate that the instability of ABRSs containing non-bedding fissures goes through several stages, including tension of the rear rock layers, reverse bending of the rock layers, formation of the main fracture plane, and secondary failure. The initiation pattern of rock bridges between fissures significantly affects the post-failure deformation of rock layers. Additionally, tensional failure at gentle-dip fissures, occurring under shear action, is the main cause for inducing reverse bending of the fractured rock mass. This eventually leads to the formation of a stepped main fracture plane, resulting in the evolution of the slope into a reverse bending collapse zone and a block-reverse bending collapse zone. At approximately one-third of the slope height, the residual sliding force of the rock layers reaches its maximum, which is also the location where fissure deformation is most prominent and the stress situation is most complex. Moreover, the stability of ABRSs containing non-bedding fissures is more sensitive to the internal friction angle between rock layers, the length of non-bedding fissures, and the angle between fissures and rock layers.