Study On Dynamic Warnning Method Of Bank Slopes In Deep-Cut Valley During The Course Of Excavation

Most large-scale Hydropower Projects which are being built or will be built lies in the area with high mountains and gorges in southwest of China. The slopes in this area are high and steep, their geological conditions are complicated, and the histories of forming the slopes are special. For the purpose of meeting the command of constructions of hydropower projects in this area, study on dynamic warning method of slope during the course of excavation, which is the topic about the safety evaluation of slope excavation, is taken as the main topic of this dissertation. Based on the studies on safety evaluation of slope excavation and engineering background of excavation of slpes in dam site of Nuozhadu Hydropower Station, through study on inversion of initial geo-stress field of bank slopes of deep-cut valley, study on obtaining method of rock mass mechanical parameters during the course of slope excavation, study on dynamic warning index of slope monitoring during the course of excavation, the dissertation forms a relatively integrated dynamic monitoring warning method of slope excavation. In sum, the main work and conclusion including:1. Considering the influence of the history of river erosion on the initial ground stress distribution of bank slopes, the regulation of influence of breadth depth ratio of symmetrical v-shaped valley on initial ground stress field of bank slopes is discussed, and then the range of breadth depth ratio of symmetrical v-shape valley which greatly influence the initial ground stress field of bank slopes in Southwestern of China under the condition of considering the factor of valley cutting is obtained. The method to obtain the layers of river erosion and their thickness is established, which gives a reasonable method to simulate the course of river erosion.2. In the light of features of bank slopes in deep-cut valleys in southwest of China, which are high and steep, their geological conditions are complicated, and the histories of forming the slopes are special, of nonlinear inversion method of initial geo-stress field of bank slopes in this area is formed, which gives scientific method to obtain the initial geo-stress field of bank slopes in deep-cut valleys in southwest of China.3. Different geological structure characters of slopes leads to different deformation regulations and failure models of slopes, and deformation regulation and magnitude of the same slope are different due to different excavation stages of the slope, so simple and static warning index of slopes monitoring obtained by engineering analogism is difficult to express the dynamic deformation features and regulation of slopes during the course of excavation. A new study route and corresponding method to obtain adequate and dynamic warning index of slope monitoring during the course of excavation are put forward, which are based on designed factor of safety and failure model of slopes, which gives scientific route and method for dynamic monitoring warning of deformation and failure of slopes during the course of excavation.4. Left bank slope of plunge pool of spillway is taken as research object. The method to obtain the initial geo-stress field of bank slopes in deep-cut valleys in Westsouth of China is applied to inverse the initial geo-stress field of dam site of Nuozhadu Hydropower Station, which gives the initial stress condition of numerical simulation of slope excavation in the dam site. The intelligent displacement inversion method is taken to obtain the rock mass mechanical parameters of the slope during the course of excavation from the elevation 770m to 755m, which gives the rock mass mechanical parameters for obtaining monitoring warning indexs during the course of excavation from the elevation 755m to 740m. The study route and method to obtain adequate and dynamic warning index of slope monitoring during the course of excavation are apply to obtain the warning index of the slope during the course of excavation from elevation from 755m to 740m, which gives references to evaluate the safety state of the slope at the stage of excavation from elevation from 755m to 740m.