Cause Analysis of Abutment Toppling Deformation of a Hydropower Station in Southwest China

Toppling deformation and failure is a typical form of instability of rock mass deformation and failure on anti-inclined slope in alpine gorge area. Based on the analysis of the distribution characteristics of the toppling deformation body in a hydropower station reservoir area in southwest China, this paper simulated the relationship between the distribution of river terraces and the toppling deformation body by using the discrete element method, and the conclusion that the influence of river downcutting on the toppling deformation is obtained. Introduction Toppling deformation is closely related to engineering construction, involving water conservancy, transportation, mining and other industries, such as Jinchuan open pit slope [1] , Jinping I hydropower station left bank slope [2] , Xiaowan Hydropower Station drinking ditch slope [3] , Changma reservoir toppling deformation slope [4] , Xiaolangdi reservoir area bank slope [5] , etc. In order to ensure the normal construction and safe operation of the project, it is of great practical significance to study the formation mechanism and stability of the toppling deformation slope. In the 1950s, foreign scholars began to study the phenomenon of toppling deformation. After decades of unremitting research, scholars have made fruitful achievements in the deformation characteristics, genetic mechanism and stability analysis of toppling deformed rock mass. Distribution Characteristics of Toppling Deformation Rock Mass 24 toppling deformation bodies are distributed in the reservoir area of a hydropower station from dam site to reservoir tail within 60 km. There are 20 toppling deformation bodies on the right bank and 4 toppling deformation bodies on the left bank. Due to the influence of regional tectonic activities, the structure of the right bank slope is dominated by reverse slope and slope, while the left bank is dominated by forward slope. According to the investigation, more toppling deformed bodies are found in the position of well-developed gully, and have a larger development range and a larger amount of deformation. Main Deformation and Failure Forms of Toppling Deformation Rock Mass According to the investigation and analysis of the deformation and failure phenomena of the toppling slope, there are four types of deformation and failure of the toppling slope: the toppling bending deformation, the toppling fracture deformation, the toppling tension deformation and the toppling creep deformation. Toppling Bending Deformation The lithology of toppling bending deformation is generally thin bedded slate and phyllite slate, mainly soft rock. In the long-term geological and history, under the effect of the gravity of rock mass itself,