The Influence Of Plants On The Loess Slope Stability In North Shaanxi

In recent years,gully reclamation project has been carried out in northern Shaanxi.In the construction process,there is a large number of bare loess slopes because of excavation,prone to landslide and collapse.To protect the loess slope and repair the ecological environment,planting plants is an effective measure.This paper is aimed at the stability of excavated slope in gully reclamation project of northern Shaanxi,using the field test,the physical test of loess,the shear test of root-soil complex and the numerical simulation software FLAC3 D in strength reduction method to study the physical properties of loess,the factors influencing the slope stability and failure mechanism,plants reinforcing function and shear strength of loess and amorpha fruticosa root-soil composite,providing technical support for slope optimization design and plant slope protection of the gully reclamation project in northern Shaanxi.The main work and results obtained from the researches of this paper are summarized as follows:(1)Yan’an is in the loess hill and gully area,raining comes seasonally.In the construction process,there is a large number of bare loess slopes because of excavation,including of no steps slopes,steps slopes and vertical slopes.These bare loess slope is influenced by factors such as natural weathering and rainfall,leading to slope surface spalling,water erosion damage,collapsible deformation even collapse and landslide.(2)By sampling and loess physical tests,researching the loess density,moisture content,specific gravity,liquid-plastic limit,grain composition and shear strength.The loess mainly consist of Lishi loess and Malan loess in the low slopes or on the top of high slopes.(3)Using FLAC3 D software in strength reduction method to simulate the slopes to analyzing the factors influencing the slope stability and failure mechanism included height,gradient,platform width,cohesive and friction Angle of loess.(4)Through the experimental study on shear strength of loess and amorpha fruticosa rootsoil composite,the effects of water content and effects of root content on shear strength of soil were analyzed.The shear strength of root-soil composite can be described by Coulomb Equation,and decreases with the increase of water content and increases with the increase of root content.With the increase of the root content,the increment of the additive cohesion is larger.The internal friction angle increment is smaller.With the increase of the water content,the increment of additive cohesion and internal friction angle decrease,but the the reinforcement effect of root increases.The reinforcement effect of amorpha fruticosa root system on loess slope was analyzed by using FLAC3 D software,it is effective while shear zone through the topsoil with roots.The reinforcement effect on deep soil is limited.