Study on the failure mechanisms of counter-tilt rock slopes with layered cataclastic structure

Counter-tilt rock slopes are a kind of rock slopes in the construction of large-scale water conservancy projects, highway(railway) projects and mine projects in China. In this paper, the whole process of deformation and failure of a rock slope with a set of joints orthogonal to the stratums is studied by means of the base friction model test. The slope deformation characteristics such as macro deformation, rock displacement, rock bending angle are analyzed to reveal the failure mechanism and the spatial force evolution law of the failure process, and the deformation zones of the counter-tilt rock slopes with layered cataclastic structure are divided. The test results show that the failure modes of the counter-tilt rock slopes with layered cataclastic structure include tensile-toppling, tensile-slip toppling and flexural tensile-(slip) toppling according to deformation and failure characterizes. The slope is divided into stable, (flexural-)tensile-toppling, compression cracking and (slippling-) toppling, and shear-slippling zones. When the slope angle or the dip angle is large, the shear-slipping zone does not exist. With increasing the slope angle, the failure of the slope body is gradually rapid, the first broken part transfers from the middle to the top of the slope, and the flexural characteristics of the rock stratums gradually decrease during the failure process;Models with a certain slope angle and a smaller dip angle are easier to deform and prone to slip along the fracture planes, while those with a larger slope angle or a larger dip angle are prone to tensile toppling failure. The deformation of the rock stratums in different parts of the slope are out-of-step, and the deformation rule conforms with the three-stage development of creep characteristics. The deformation rate is basically in horizontal orientation when the tensile deformation begins and then becomes apparent in vertical orientation after the topping failure happens, which can be taken as a judgment of the initial deformation stage. The maximum bending angle of the rock stratums which are dominated by tensile-toppling failure is obviously smaller, and the fracture planes are ladder-like. The maximum bending angle and the failure depth of the rock stratums dominated by flexural tensile-(slip) toppling are obviously larger, and the fracture planes are mostly straight line or irregular broken line. © 2021, Science Press. All right reserved.