Study On Dynamic Response Characteristics And Stability Of Bedding Rock Slope In Water Level Fluctuating Zone Of Reservoir Area

The periodic water level regulation of the Three Gorges reservoir has formed a water level fluctuation zone with an elevation of 30 m,which leads to different degrees of deterioration of the rock mass in this area and affects the overall stability of the bank slope.In addition,the number of microseisms increases significantly after the reservoir impoundment,the influence of the dynamic action of small earthquake on the long-term stability of bank slope can not be ignored.This paper relies on the National Natural Science Foundation Project "Study on the Static(Dynamic)Instability Mechanism and Stability Control of Slope under the Condition of Deterioration of Rock Mass in the Water Level Fluctuating Zone in the Reservoir Area(41972266)",taking the bedding rock slope of Wushan water level fluctuating zone in the Three Gorges Reservoir Area as the background,the stability of the bedding rock slope under multiple micro earthquakes is studied,and the influence factors and sensitivity of different stability are analyzed.The main research contents and results are as follows:(1)Based on field investigation and geological data,this paper summarizes the deformation characteristics and failure modes of the bank slope in water level fluctuating zone of Wushan section,and generalizes the structural forms of two typical bedding slopes.The results show that: the rock bank slopes in Wushan section are mostly of erosion denudation,dissolution latent erosion and collapse type;the bedding slopes in the water level fluctuation zone are mostly of stress concentration zone development,and the rock mass deterioration is serious.(2)Taking the typical bedding slope of Wushan section as the background,two groups of model tests were designed,including similarity relationship design,similar material selection and ratio,slope construction,loading wave selection and loading scheme,etc.The results show that: the acceleration response of model slope has vertical and horizontal amplification;with the increase of seismic frequency and seismic load amplitude,the dynamic response of the slope is more intense;With the accumulation of slope damage,the acceleration response of the model slope gradually weakens.The failure process of the model slope is as follows: the secondary joints between the layers pull apart,and then the rock surface slides gradually,and the overall performance is the sliding of the rock block layer by layer.(3)The numerical model is established by using UDEC discrete element method to analyze the process of displacement development and instability of slope under the action of several small earthquakes.The results show that the slope displacement increases gradually with the increase of the number of earthquake actions,and the variation amplitude presents the law of slow first and fast later;under the action of long-term microseismic,the stability of the slope in the water level fluctuating zone will gradually decrease,forming a large number of "loose mountain" and "cracked mountain".(4)The influencing factors and sensitivity of slope long-term stability are discussed.The results show that: with the increase of slope height,slope angle,seismic amplitude,seismic frequency,deterioration depth of rock mass in water level fluctuation zone and the decrease of deterioration coefficient of rock mass discontinuity in water level fluctuation zone,the slope is more prone to instability;the order of sensitivity is seismic amplitude,slope height,seismic frequency,deterioration depth of rockmass in water level fluctuation zone,slope angle and deterioration coefficient of rock mass discontinuity in water level fluctuation zone.