Static And Dynamic Stability Of Fill Body Used To Protect Bank Slope In High Seismic Area

In the construction of highway projects along the reservoir in high intensity area,the problem of damage to highway engineering caused by instability of bank slope of reservoir is often encountered.In order to protect the safety of highway facilities,the bank slope with poor stability needs to be treated or reinforced.It is feasible to use fill to improve the stability of the bank slope of reservoir and protect the subgrade slope along the Bank of the reservoir.For the reservoir slope protection fill in high intensity area,because of the lack of deep research,it is not clear the influence of reservoir water level dynamic change and earthquake action on its stability,so it is necessary to carry out relevant research.Taking the bank slope of gaoliangdi super large bridge on geqiao Expressway in Yunnan Province as the engineering background,this paper carries out the experimental study on the vertical permeability characteristics of bank slope filling materials.Combined with ABAQUS and FLAC 3D finite element software,the stability and deformation law of bank slope fill under the action of static water level and sudden drop of water level,as well as the influence of compactness on the stability of bank slope fill are studied and analyzed;the stability and dynamic response characteristics of bank slope fill under the action of earthquake are studied and analyzed.Three different bank slope protection schemes are compared and analyzed,and the optimal scheme is determined.The specific research contents and conclusions are as follows:(1)Based on the constant head permeability test,the effects of particle size distribution and dry density of samples on the permeability characteristics of bank fill are discussed.Combined with numerical simulation,the influence of compactness on the stability of bank fill under the action of static water level and sudden drop of water level is studied.The results show that the permeability coefficient of bank slope fill is directly proportional to the content of coarse particles and inversely proportional to the dry density;the stability of the embankment is affected by the dry density of the fill,and in a certain range,the higher the density,the better the stability of the embankment.(2)Using ABAQUS finite element software,the stability and influence law of bank slope fill under static water level and sudden drop of water level are studied.The results show that with the increase of water level,the safety factor of bank slope fill decreases first and then increases.At the same elevation,the pore water pressure of each point shows a decreasing trend in the process of sudden drop of water level,and the inner pore water pressure is higher than the outer pore water pressure.With the increase of water level drop height,the stress and displacement of bank fill increase,and the safety factor decreases.When the height of sudden drop of water level exceeds a certain value,the bank slope may lose stability.(3)Based on the quasi-static method and dynamic finite element method,the stability and dynamic response characteristics of bank fill under earthquake are analyzed by numerical simulation.The results show that static water level action and earthquake action can slow down the influence of stability reduction caused by single action.The peak acceleration and horizontal displacement of the middle and lower part of the filling body are larger,that is,the stability of the middle and lower part of the filling body is worse than that of the upper part.(4)Taking gaoliangdi super large bridge project of geqiao expressway as an example,through comparative analysis of the stability and failure forms of bank slope fill with three different slope ratios,it is considered that the best slope ratio is 1:2.5,which can meet the stability requirements and save the cost.