Stability Analysis Of The Slope With Bedrock Under Rainfall And Earthquake Coupling Action

With the rapid development of western economy and the increasing number of mountain construction projects,the stability of foundation-covered slope has become very prominent.The Slope with bedrock has the remarkable characteristics of wide distribution,high frequency,poor regularity and great difficulty in prevention and cure.After the Wenchuan earthquake,more than a thousand aftershocks occurred in the earthquake disaster area,and the rainfall and earthquake have a great impact on the slope stability,so it is very necessary to analyze the instability mode and instability mechanism of the Slope with bedrock under the rainfallearthquake coupling condition.In this paper,the effects of different rainfall time,different static time,different retaining structures and different soil types on the stability of foundation-covered slope under rainfallseismic coupling are studied by model test.the failure critical acceleration,failure process,failure mode,failure mechanism and dynamic response law under earthquake are summarized and analyzed.The main results are as follows:(1)under the coupling action of rainfall and earthquake,the Slope with bedrock shows three failure modes: the whole plus local failure,the upper part of the slope slipping along the foundation cover interface,the local failure of the lower part sliding along the soil,and the local failure of the upper and lower parts of the slope sliding along the soil.The rainfall time and the standing time after rainfall saturation will not affect the failure mode,but only have a certain influence on the length of the internal slip surface of the slope soil.Setting the retaining structure and changing the soil type have a significant impact on the failure mode.(2)under the influence of different factors,the critical acceleration of Slope with bedrock has different rules.The critical acceleration of failure increases with the increase of rainfall time,the critical acceleration of failure decreases with the increase of standing time,the critical acceleration of failure increases with the setting of retaining structure,and the critical acceleration of failure shows the characteristics of gravel soil > sand >silty sand when the type of soil is changed.(3)under the influence of different factors,the dynamic response of foundation overlying slope shows different rules.With the increase of rainfall time,the magnifying effect of the measuring point at the bottom of the slope increases,while that of the measuring point on the slope and in the slope decreases;with the increase of static time,the magnifying effect of soil increases at first and then decreases,and the magnifying effect of slope increases with the setting of anti-slide pile or frame anchor.With the change of soil type,the magnification effect of gravel soil is limited compared with sand,while that of silty sand is smaller than that of silty sand,and that of slope soil is larger than that of silty sand.(4)the failure mechanism of the Slope with bedrock under the coupling action of rainfall and earthquake is mainly due to the fact that part of the soil of the slope is saturated and softened by rainfall,and the pore water pressure of the saturated soil circulates between a sharp increase and a sharp decrease under the action of earthquake.as a result,the soil liquefaction occurs and the shear strength decreases greatly,and then the Slope with bedrock is destroyed under the action of seismic force.