STUDY ON TOPPLING MECHANISM AND AFFECTING FACTORS OF ANTI-DIP ROCK SLOPES WITH SOFT-HARD INTERBEDDED STRUCTURE

In the Three Gorges Reservoir area, there are many anti-dip slopes with soft-hard interbedded structures in the Gongjiafang-Dulong section of Yangtze river, and the phenomena of flexural toppling are developed. This paper explores the mechanism of flexural toppling, as well as the effect of slope morphology, structure, and mechanical parameters of rock mass on the toppling. Based on the centrifugal model test and discrete element numerical simulation, this paper analyzes the toppling process of soft-hard interbedded toppling slopes and the failure mechanism under external disturbance. The single factor analysis method and orthogonal design method are combined to study the influence factors of toppling. And the sensitivity of each factor is obtained by range analysis. The random fractures are preset in the rock strata to get the initiation and extension laws of the fracture surfaces. The results show that the centrifugal model test and the discrete element simulation can well reproduce the toppling process, and the coincidence between them is good. The toppling process can be divided into three stages: initial deformation, steady deformation, and unstable failure. After the rock bending accumulates to a certain extent, the arc fracture surfaces form rapidly. The slope can form a multi-level fracture from bottom to top. Under the external disturbance, the toppling part can gradually form progressive backward collapse along different fracture surfaces from the outside to the inside. The stability of the anti-dip slope is mainly affected by the slope shape and structure. The sensitivity of influence factors is as follows: slope angle>dip angle>slope height>slope shape>layer thickness ratio>layer thickness. The larger the slope angle, dip angle and slope height are, the more convex the slope shape is, the smaller the thickness difference between soft and hard strata is, and the easier the slope is to be damaged. The slope damage scale is mainly controlled by the dip and slope angle. The research results have guiding significance for the reinforcement and treatment of such slopes.