Research On The Deformation And Failure Characteristics And Stability Of No1 Bank Collapse Of Liuluogou Of Qiaoqi Reservoir In Baoxing County Sichuan Province

Qiaoqi Reservoir is located in Qiaoqi Tibetan Township,Baoxing County,Ya'an City,Sichuan Province.No1 bank collapse of Liuluogou accumulation body is located at the middle of Liuluogou mouth of the left bank of the dam.The reservoir impoundment in 2008 resulted in a series of deformation and damage to the bank slope,which had a serious impact on the smooth passage of the provincial highway S210 and the residential housing here,and at the same time had huge security risks.Based on the field geological survey,this paper puts forward the mechanism and main influencing factors of Nol bank collapse of Liuluogou accumulation body,under the premise of grasping the bank slope shape,stratigraphic structure and material composition.The influence of displacement,descent and long-term lifting cycles on the bank slope is simulated by ANSYS and FLAC3D.The stability analysis of displacement,stress and shape distribution of No1 bank collapse of Liuluogou is analyzed.Finally,the reliability of the simulation results is verified by comparing the numerical results with the field monitoring data.The main results of this paper are as follows:(1)Through field investigation,the engineering geological conditions and deformation and failure characteristics of the slope of No1 bank collapse of Liuluogou accumulation body are analyzed.According to the characteristics of site deformation and failure,the geological conditions of bank collapse and the operation mode of reservoir operation,the deformation and instability mechanism of collapse and the main factors affecting the stability of bank collapse are put forward.The rise and fall of the reservoir water level are the main external factors that affect the stability of the bank slope.When the water level drops,the deformation and failure of the slope are more strong,and the characteristics of the multi-level development are bottom-up.(2)The stability of two dangerous sliding surfaces of No.1 Liuluogou accumulation body is calculated by using the transfer coefficient method.The stability of the nature and rainstorm conditions of 2140m water level,and the stability of the water level dropped to 2060m is calculated.It is concluded that the slope is stable or basically stable in the natural state of 2140m water level.Under the rainstorm condition,the stability coefficient is the lowest,and the slope is in the critical state of nstable and less stable.(3)Analysis the simulation results of FLAC3D.The large deformation area in the simulation results is compared with the area of the field survey,and the scale range is basically consistent.Compared with the rising water level,the absolute value of the displacement of the bank slope is higher than the dropping water level,and the deformation scale and the shaping area are obviously larger,and the large deformation area is concentrated in the bank In the lower part which verifying the slope instability mechanism proposed.(4)Through the numerical simulation results of the accumulation of the reservoir water level,the accumulation of displacement is obviously slowed down.There is a significant difference in the cumulative deformation between the rise and fall of the reservoir during one cycle,and the time curve of displacement shows obvious ladder.(5)Analyze the actual monitoring data of the field and compare it with the FLAC3D simulation results.The simulation results are consistent with the field monitoring data,and the simulation results are verified by the comparison of three conditions of the two monitoring points inside and outside the bank.At the same time,it is verified that the reservoir water level fluctuation is the main external factor that affects the stability of the bank slope,and the stability of the bank slope is relatively worse during the reservoir water level dropping.