Analysis Of The Influence Of Rainfall And Excavation Methods On The Stability Of Loess Slopes

With the rapid development of China's economic construction,large-scale infrastructure construction has been carried out in the Loess Plateau.However,due to the poor geological environment,concentrated rainfall and limited land resources,a large number of slope toe excavations and graded slope cuts were carried out during the construction of the project.Unreasonable excavation methods destroyed the original slope The shape affects the stability of the slope,which causes many geological disasters in the construction of the loess area.Therefore,it is of certain significance to analyze the deformation and failure of loess slope and its stability under the action of rainfall and excavation.This article will take a loess slope in Qingjian County,Yulin City,Shaanxi Province as the research object,and will pass field investigations,drilling exploration and indoor geotechnical tests.On this basis,Geo-Studio and Midas/GTS finite element numerical simulation software will be used to simulate the influence of rainfall and excavation on the stability of the slope,and the sensitivity of slope shape factors to the stability of the slope will be analyzed by orthogonal test method.The main research results are as follows:(1)The main forms of deformation and failure of the loess slope are: collapse,landslide,water hole,slope erosion and slope spallation.Its main factor has the internal influencing factors and the external influencing factors,the internal because of the slope topography and formation lithology,the external because of the rainfall and the unreasonable excavation and cutting slope.(2)It can be concluded from the laboratory test that the upper soil mass of the slope has more powder grain content and less clay grain content than the lower soil mass,and the pores of the upper soil mass are more developed than those of the lower soil mass.The permeability of soil in the upper part of the slope is greater than that in the lower part of the slope.When the soil moisture content increases,the internal friction Angle and cohesion of the slope will decrease,which affects the stability of the slope.(3)In the process of rainfall on the slope,the soil at the foot of the slope is greatly affected by rainfall.When the infiltration depth of rainwater reaches the interface of soil layer with different permeability,the soil will be greatly affected by rainfall.The greater the rainfall intensity and the longer the rainfall duration,the greater the influence on the slope stability.When the total amount of rainfall and the duration of rainfall remain unchanged,the later the peak rainfall occurs,the greater the influence on the slope stability will be.(4)In the process of excavating the slope foot,the larger the excavation footage and the slope angle,the more serious the influence on the stability of the slope will be.The main failure mode of slope foot is sliding failure.The sensitivity and primary and secondary order of the influence of slope shape factors on the stability of the slope are as follows: single-grade slope rate > platform width > single-stage slope height;In the process of grading excavation,the deformation and failure mode of the slope is shallow landslide.The slope stability can be improved by slowing down the single-stage slope rate,reducing the single-stage slope height and increasing the platform width.