Analysis On The Landslide-generated Waves Of Yalong River Basin And Its Impact On Reservoir Area

When reservoir bank landslide loses stability,the landslide runs into the river channel rapidly that causes the surge.The slope instability may be caused by a variety of factors.The water level rapid changes in the reservoir area will lead to landslides during the impounding and sluicing.Long term water flow,wind and wave erosion may contribute to landslide instability along the weak interlayer.Besides the serious geological disasters such as tsunamis,earthquakes will do these phenomena.Judge the landslide point as the center,the landslide provoked a huge surge to push towards the upstream and downstream,huge stone and earth sliding into the river will not only block the channel but decrease storage capacity which will influence the regulation of reservoir.The surge will cause great harm to upstream and downstream towns,docks and hydraulic structure.The water level of Jinping first class hydropower station located in the upper reaches of the Yalong River will reach 1840 m in the third impounding.The field geology investigation and review was carried out towards the bank stability,especially for the landslide and deformable body in the upper reaches of river.The bank's slope and deformation in the basin is serious.The slip surface was not formed after rock mass dumping and no sign of sliding in the natural and storm condition.Thus the global bank stability was poor.Due to many potential dangerous banks was existed in the upper reaches of Yalong River.The research of these problems seems to be more imminent nowadays.On the basis of summarizing prodecessors' impirical formula of landslide surge,taking Jinping hydropower station's biggest landslide(Shuiwen station landslide)as research project,through the method of comparation between theoretical analysis and numerical simulation for research and demonstration.This paper selected the surge empirical formula of academician Pan Jiazheng to calculate of landslide instability after comparation and analysis.In this way we can get the data of maximum sliding speed,the maximum initial surge height value,opposite side of the surge height and the damsite height of surge.In the numerical simulation using the classic fluid numerical software –Fluent and VOF method of software to track the free surface flow field,the moving of landslide was simulated by dynamic mesh technology and UDF program.By establishing the section in the river to apply the probe to extract thesurge data,analyzing the result of the software Fluent numerical simulation of Shuiwen station landslide instability,analyzing time domain analysis,surge height fitting analysis and flow analysis of the channel probe data to find out the discipline.To demonstrate whether the possibility of surge overtopping dam occurred in Jinping hydropower station or not when the surge reaches the damsite.The error(10 percentages)is within normal limits after the calculation.In order to demonstrate the influence of characteristic values between the sliding speed,depth and volume change rate by 6 numerical simulation cases.The sensitivity factors of characteristic value are sliding speed,water depth,and reservoir volume change rate according to sensitivity in row.The surge energy attenuation discipline conforms exponential function in time and space basically,By studying the discipline of landslide surge deformation to establish the scheme the landslide strengthening and controlling.The research results of this paper are based on theoretical analysis and numerical simulation.According to Jinping specific project of Yalong River,the research result can be used as analytical method to the unstable large-scale landslide risky prediction.It is suggested to demonstrate the rationality via the model method.The results of the study will provide an effective method,feasible direction and reasonable data range for similar projects.