Study On The Formation Mechanism And Stability Of Songping Large Toppling Deformation Body Of Jinchuan Hydropower Station

The Songpoping slope of Jinchuan Hydropower Station is a high slope with anti-dip rock,and the structure of the slope shows obvious characteristics of “upper hard and lower soft”.During the evolution of the river valley,the rock mass experienced strong unloading and toppling deformation,which seriously threatened the study of the toppling deformation,characteristics of the sloping slope,the evolution process of the river valley and its genetic mechanism,the stability of the slope,etc.,which have important theoretical significance and engineering.value.This paper takes the Xinzhagou Songping slope of the Jinchuan Hydropower Station on the Dadu River as the research object,combined with the on-site geological survey,summarizes and summarizes the inversion deformation characteristics of the Xinzagou Songping slope,and adopts a combination of geological analysis and numerical simulation to gradually evolve The process and genetic mechanism and the values of the cohesive force and internal friction angle of the extremely strong toppling rock mass were studied in depth,and the main achievements and opinions were as follows:(1)The development scope of the dumping deformation body of Songping slope in Xinzhagou is as far north as Zhangjiagou,south as Jiangjiagou,and as low as Xinzhagou and Dadu River.The shape of the plane is "shovel",narrow at the top and wide at the bottom,and the shape is basically symmetrical.The leading edge is about 900 m wide,the middle is about 600 m wide,and the trailing edge is about 400 m wide.The average thickness is about 50 m,the area is about 8.3×105 ?,the estimated volume is about 4.2×107m3,and the elevation is 2200m?2800m.(2)According to the statistics of Pingdong,the rock structure of the Songping slope in Xinzhagou is mainly a thin layer-interlayered structure;the lower part of the slope structure in the direction of the Xinzhagou slope is a layered reverse structure;the middle and upper part is a layered structure Reverse structure,the surface is a nearly horizontal layered structure;the slope structure of the slope on the right bank of Dadu River is mainly a layered lateral structure.(3)According to the on-site dumping deformation characteristics survey,the upper and middle parts of the slope are mainly composed of hard rock,showing massive dumping deformation;the lower part is mainly composed of soft rock,and showing bending dumping deformation.The depth of XHPD1 extremely strong dumping deformation is about 40 m,the depth of XHPD2 extremely strong dumping deformation is about 55 m,and the depth of XHPD3 extremely strong dumping deformation is about 70 m.The depth of extremely strong dumping deformation increases with the increase of elevation.(4)Comprehensive analysis of on-site engineering geological survey and Udec two-dimensional discrete element software numerical simulation results,the evolution process of the tipping deformation of the Songping slope in Xinzhagou can be summarized as follows:(2)Unloading and resilience deformation in the middle and lower "soft rock area"-dumping deformation phase in the middle and upper "hard rock area",(3)bending and dumping in the lower "soft rock area"-partial failure phase of massive dumping in the upper "hard rock area".(5)Using the two-dimensional finite element software RS2,the strength reduction method is used to calculate the stability of the Songping tipping deformation slope under different parameter value schemes under seismic conditions,so that it is more reasonable to invert the slope with extremely strong tipping deformation rock mass The cohesive force and internal friction angle,the law of stability change and deformation and destruction characteristics.(6)Four basic schemes are used to invert the cohesion and internal friction angle of the rock mass with extremely strong dumping deformation in the Songping slope.The results show that: the steady state and actual situation calculated by the parameters used in schemes 1,2,and 3 Inconsistent;the slope stability calculated by Option 4 is more consistent with the actual situation,and the selected parameters are more reasonable;and the sensitivity analysis of the shear strength parameters is performed.The order of sensitivity from high to small is: Cohesion in soft rock area> Cohesion in hard rock area>friction angle in hard rock area>friction angle in soft rock area.