Study On Deformation Response Of Left Bank Slope Impoundment Of Jinping ? Hydropower Station

Jinping I hydropower station is located in the middle and lower reaches of Yalong River in Liangshan Prefecture,Sichuan Province.The dam is a typical double curvature arch dam with a height of about 305 m.its standard water level is 1880 m and the height difference with the original river surface is 240 m.The deformation of the left bank slope of Jinping I Hydropower Station after impoundment has attracted the attention of many scholars.In this paper,the basic characteristics of the left bank slope and the signs of deformation and failure are summarized through the field investigation combined with the previous investigation data,and the deformation area of the left bank slope is divided.Based on the monitoring data,the deformation characteristics and mechanism of the left bank slope are analyzed.The deterioration law of rock and soil mass in the process of water storage is studied by laboratory test.Geo Studio seep / W was used to study the dynamic characteristics of groundwater seepage field on the bank slope in each impoundment stage.On this basis,FLAC3 D software is used to simulate the deformation response process of the left bank slope under water storage,so as to analyze and discuss the deformation mechanism and deformation response law of the left bank slope under water storage.The specific research contents and results are as follows:(1)Through on-site investigation and study of survey data,the engineering geological conditions of the left bank slope are preliminarily understood.On this basis,the basic characteristics and deformation signs of the left bank slope are summarized,and the deformation area of the left bank slope is divided based on it.(2)By analyzing the data of surface deformation monitoring points and deep deformation monitoring points in each deformation area,it can be seen that the deformation of the dump deformation body in deformation area I is still continuing after water storage,and the fluctuation of reservoir water level has little influence on its deformation development.The deformation of the second area is mainly affected by the fluctuation of the reservoir water level.The uplift of the water line makes the deformation of the area change from settlement to uplift in the vertical direction.The deformation of the three areas is mainly controlled by f42-9 fault,lamprophyre vein X and deep-seated fracture,which is greatly affected by water storage.The deformation of the fourth zone is in the adjustment of fluctuation due to the influence of the abutment thrust,and the deformation of the whole zone is small due to the suppression of the abutment thrust.(3)In this paper,the weakening laws of mechanical properties of rock and soil under two different working conditions of long-term water saturation and dry wet cycle in the process of water storage are studied through laboratory tests,which provides a basis for the selection of parameters for subsequent numerical simulation.(4)Through Geo Studio seep / W software,the dynamic change characteristics of groundwater seepage field of bank slope in each impoundment stage are simulated.When the change rate of reservoir water level is greater than the permeability coefficient of bank slope,the change of pore water pressure and phreatic line in the seepage field of bank slope will lag behind the change of reservoir water level no matter whether the reservoir water level is rising or falling,and when the permeability coefficient is fixed,the greater the rise and fall rate of reservoir water level,the more obvious the lag phenomenon.(5)Through FLAC3 D software to simulate the deformation response process of the left bank slope under water storage,the deformation mechanism of the left bank slope under water storage is obtained: the continuous deformation of the left bank slope is a new normal deformation adjustment reaction,which is generally generated under water storage conditions and engineering structure load,and is controlled by the geological structure of "Anti dip layered structure + deep fracture + segmentation of main structural plane of extroversion" The conceptual model of deformation adjustment can be summarized as a comprehensive deformation mechanism of "continuous toppling of the upper part,deep tension crack,relaxation of the shallow part,coordination of the lower part and the dam body".