| Qiaoqi reservoir is the leading reservoir in Baoxing River Basin.It is located in Qiaoqi Township,Baoxing county.No.3 accumulation bank collapse deformation body of karigou is located on the left bank of Qiaoqi reservoir.Frequent changes of water level after impoundment of the reservoir lead to a series of deformation and failure of the bank slope of the accumulation body,which has a serious impact on the production and life of the residents on the slope and at the same time threatens the safety of vehicles on the highway.In this paper,the boundary conditions,scale,material composition and deformation and failure characteristics of Karigou No.3 deposit body were identified by field geological survey and GPS displacement monitoring data distributed on the collapsed bank deposit body,and the formation mechanism and influence factors of deformation and instability failure of Karigou No.3 deposit body were analyzed.Through the GEO-Seep module of the GEO-Studio software,the internal seepage characteristics of the accumulation body slope reservoir under the change of water level were simulated,and the seepage data obtained were coupled with the GEO-Sigma module to obtain the stress-strain field variation diagram of the landslide.Then,the results were compared with the actual monitoring results of GPS to verify the reliability of the numerical simulation and reveal the collapse mechanism.Finally,according to the difference of material composition,the stability analysis of the deformed body is carried out in three longitudinal regions under different working conditions,and the treatment engineering measures are proposed.The main conclusions of this paper are as follows:(1)Combined with the operation mode of reservoir water level,the main factors affecting the collapse and instability deformation of Karigou No.3 accumulation body are analyzed.The rise and fall of reservoir water level is the main inducing factor affecting the stability of the landslide,the soil condition of the slope itself is the main internal factor,and the instability type of the landslide is creep slip-tensile crack.(2)The internal seepage field of the accumulation body was analyzed,and the change curve of pore water pressure and the morphometric change diagram of the seepage line were obtained under the condition of reservoir water level rise and fall.The analysis shows that due to the hysteresis effect of the seepage field in the slope,the stress state in the slope changes with the change of reservoir water level,which leads to the redistribution of stress in the slope and affects the stability of the slope.(3)Coupling the seepage field simulation results with the stress field,the variation curve of stress and strain in the slope body with the rise and fall of reservoir water level was obtained.By comparing the field GPS monitoring displacement data,it is shown that the slope is more prone to sliding failure in the process of reservoir water level decline,and the vertical direction of the landslide is the main direction of sliding.(4)Through stability calculation and analysis,it is concluded that under the condition of reservoir water level rise and fall,the stability coefficients of No.3 collapsed bank accumulation body show a trend of decreasing first and then increasing;When the reservoir water level drops to 2120 m,the stability reaches the lowest,indicating that the accumulation body is in an unstable state during the reservoir water level decline.It is suggested to adopt "anti-slide pile" retaining project outside the highway around the lake. |
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