Study On The Stability Of Reservoir Bank Slope Under The Combined Action Of Water Level Rise And Fall And Rainfall

Reservoir bank instability damage often occurs during the rise and fall of the reservoir water level,and rainfall is also the main inducing factor for bank slope instability.Study the fluctuation of the reservoir water level,the variation of the groundwater level of the bank slope under rainfall conditions,and the change in the stability of the bank slope region.It is of great significance to predict performance and reduce the loss of life and property caused by bank slope instability.This paper takes Shanmei Reservoir as the research object,selects a suitable bank slope groundwater level calculation method based on the collection and sorting of the reservoir area rainfall,reservoir water level changes,geology and other data,and establishes a reservoir bank regional stability calculation model based on the Scoops 3D model.The bank slope stability state analysis under multiple working conditions,a detailed study of the low stability area of the bank slope,and the comparison and verification of the simulation results with the help of indoor model tests.The main conclusions obtained are as follows:(1)The Boussinesq unsteady seepage analytical solution was used to calculate the distribution of groundwater level on the bank slope.The results show that: during the decline of the reservoir water level,the faster the water level decline rate and the greater the height of the reservoir water level decline,the more obvious the hysteresis effect of the infiltration line in the bank slope,and the curvature of the infiltration line The larger the value,the greater the seepage pressure pointing to the outside of the slope;during the rise of the water level,the greater the height of the reservoir water level rise and the higher the rate of rise,the more the infiltration line in the slope lags behind the water level outside the slope,the more curved the infiltration line is and the more the seepage pressure in the slope The larger the permeability coefficient is,the less obvious the hysteresis effect of the wetting line and the smaller the degree of bending of the wetting line.(2)Using the regional slope stability analysis model Scoops 3D to analyze the stability of the bank slope under multiple conditions,it is found that under the condition of no groundwater and 90 m normal water level,most of the bank slope is in a high stability state,and the area of the low stability area is relatively large.Less and sporadic distribution;in the process of falling water level,the stability of the bank slope decreases significantly,and the greater the rate of decline of the reservoir water level,the more unfavorable the stability of the bank slope,and the greater the proportion of bank slopes in the low-stability state;the rising state of the reservoir water level Below,a larger rate of rise of the reservoir water level is beneficial to the stability of the bank slope;the degree of influence of rock and soil mechanical parameters on the stability of the bank slope is: internal friction angle>soil weight>cohesion.(3)Using Geo Studio to refine the low-stability area,it is found that the bank slope stability decreases first and then increases during the decline of the reservoir water level.The most dangerous water level appears roughly at 1/3～1/2 of the total drop height of the reservoir water level The greater the rate of water level drop is,the more unfavorable the stability of the bank slope,while the greater the rate of rise of the reservoir water level is beneficial to the stability of the bank slope;The impact of rainfall on the stability of the bank slope is more obvious;the rainfall combined with the lowering of the reservoir water level is the most unfavorable to the stability of the bank slope.(4)The results of the bank slope regional stability analysis results and the general conclusions obtained from the two-dimensional analysis in this paper are in good agreement with the physical model test results conducted by Jiang Qiangqiang of the University of Chinese Academy of Sciences.The research method of regional bank slope stability system has good applicability,and the research method in this article has certain reference value for bank slope stability analysis.