Failure Probability Analysis Of Heterogeneous Reservoir Bank Slopes And Simulation Of Induced Surge Under Sudden Drop Of Water Level

As an important part of large water conservancy projects such as reservoirs and hydropower stations,the stability of reservoir bank slope is greatly affected by the sudden drop of reservoir water level.During the sudden drop of reservoir water level,the seepage force points to the outside of the slope,which is very unfavorable to the slope stability.In addition,due to its special geographical location,the huge surge induced by the instability of the reservoir bank slope often poses an immeasurable threat to the safety of life and property of people along the coast and downstream.Therefore,it is of great scientific significance and engineering application value to study the instability probability of reservoir bank slope and the induced surge propagation law under the condition of sudden drop of water level.In this regard,the main research contents and related conclusions of this paper are as follows :(Ⅰ)The research progress of the calculation method of bank slope stability,the probability analysis method of bank slope instability,the search method of sliding surface position,the physical experiment and numerical simulation of surge at home and abroad are systematically investigated.(Ⅱ)The stability analysis of reservoir bank slope under sudden drop of reservoir water level is carried out by using limit equilibrium method and strength reduction method.It is found that the safety factor of heterogeneous reservoir bank slope calculated by strength reduction method is smaller and the sliding surface is deeper,and the calculation results are more practical.On this basis,MCS(Monte Carlo method)simulation combined with limit equilibrium method is used to analyze the instability probability of heterogeneous reservoir bank considering the spatial variability of soil parameters.It is found that when the spatial variability of parameters is ignored,the instability probability of reservoir bank slope will be underestimated.Therefore,the important factor of spatial variability cannot be ignored in the risk assessment of reservoir bank slope.(Ⅲ)The strength reduction method is used to analyze the stability of the threedimensional reservoir bank slope under the sudden drop of reservoir water level,and the Kmeans clustering method is proposed to determine the position of the sliding surface and the volume of the sliding body.On this basis,the hydrodynamic software is used to visually simulate the surge induced by the instability of the reservoir bank slope,and the time and height of the first wave are obtained.It is found that the propagation law of waves conforms to the law of conservation of energy,and as the propagation distance increases,the wave propagation height gradually decreases and eventually tends to zero.In addition,the propagation law of surge induced by the instability of reservoir bank slope under the sudden drop of reservoir water level is studied and analyzed.The results show that with the sudden drop of reservoir water level,the maximum surge height induced will increase continuously,but the time of the first wave is not much different,which provides theoretical support for the prevention and control of surge induced by the instability of reservoir bank slope.(Ⅳ)The limit equilibrium method and finite difference strength reduction method are used to analyze the stability of reservoir bank slope under the action of anti-slide pile and three-dimensional vegetation network,and then the effects of the above two protective measures on the stability of reservoir bank are compared and analyzed.The results show that these two protective measures have good effects on the prevention and control of reservoir bank slope instability,and the high-density three-dimensional vegetation network has a more obvious effect on the stability of reservoir bank slope.