| The bank collapse deformation body of Yongshou Temple lies on the strip ridge between the Niba Ditch and the Kari Ditch on the right bank of the reservoir of the Qiaoqi Hydropower Station.Since the storage of Qiaoqi Reservoir at the end of 2006,a series of deformation and destruction have taken place on both sides of the strip ridge,which poses a serious threat to the safety of temple buildings on the ridge platform and monks' lives and property.Based on the site investigation,this paper analyzes the shape and scale,material composition and deformation and failure characteristics of Yongshou Temple bank collapse,puts forward the main influencing factors of bank collapse deformation and instability,and analyzes the changes in shear strain increment and displacement of bank collapse by FLAC3 D numerical simulation,and studies the collapse mechanism of bank collapse.Then the stability of Yongshou Temple bank collapse is analyzed by the limit equilibrium method.Finally,according to the deformation and failure characteristics and stability analysis of the bank slope,three treatment schemes are put forward,and the optimal scheme is given through the comparison and selection of the schemes.The main contents and results of this paper are as follows:(1)Through the site investigation,the engineering geological conditions and the deformation and failure characteristics of Yongshou Temple bank collapse deformation body are found out,and on this basis,the factors that cause the deformation and instability of Yongshou Temple bank collapse are analyzed by combining with the operation mode of the reservoir.The geological characteristics of the bank slope are the internal factors affecting the bank collapse.The reservoir water level fluctuation is the main external cause that affects the deformation and instability of the bank slope.(2)The mechanism of bank collapse on both sides of Yongshou Temple is simulated and analyzed by using FLAC3 D numerical simulation software.The analysis results show that the shear strain increment zone and large deformation area are mainly located at the front edge of the bank slope after the reservoir impoundment.As the reservoir water level rises to the normal water level of 2140 m,the shear strain increment zone and the large deformation area develop to the middle,and the front edge of the bank slope is deepened.When the water level falls from 2140 m to 2135 m,the hydrodynamic pressure formed by the water head difference between inside and outside the bank slope promotes the surface creep,causes the back edge of the bank to crack,and the shear strain increment zone expands to the back edge,and the rock and soil at the front edge of the bank slope are further destroyed by the flow erosion.The bank slope is characterized by bottom-up progressive damage,which is a typical collapse.(3)The stability of 9 typical profiles on both sides of the bank slope of Yongshou Temple is calculated and analyzed by the limit equilibrium method.With the most unfavorable impoundment condition of falling from 2140 m to 2135 m and the normal impoundment of 2140 m as the basic control conditions,and then the natural,rainstorm and earthquake conditions are considered respectively to calculate quantitatively.The calculation results show that the bank collapse deformation bodies on both sides of the thin ridge of Yongshou Temple are in an understable to unstable state at the present stage of reservoir operation.(4)On the basis of summarizing the existing measures and applicability of all kinds of bank collapse prevention and control measures,three bank collapse treatment schemes are put forward in view of Yongshou Temple bank collapse deformation body.The Scheme II is recommended as the optimal scheme by the scheme comparison,that is to use the lattice anchor cable and the ladder type anchor retaining wall. |
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