Study On Mechanical Properties And Engineering Application Of Root Soil Complex Of Grass And Shrub Vegetation

Vegetation slope protection can stabilize the slope through the mechanical effect of root reinforcement.Compared with the traditional engineering slope protection,it can not only meet the requirements of improving the safety and stability of the exposed slope,but also realize the purification of the atmosphere and the restoration of the environment through its own ecological functions.It has a sustainable slope protection technology.In this paper,by means of laboratory tests,numerical simulation and theoretical analysis,the compression deformation characteristics,shear strength characteristics and permeability characteristics of the root soil complex of white clover,spot thatch and Chinese fir vegetation are analyzed,and the effects of slope height,slope and rainfall conditions on slope stability are studied.The following results are obtained:(1)The water content and organic matter content of white clover,spot thatch and Huakong wood vegetation sites decreased gradually from top to bottom along the soil depth.The water content is positively correlated with the compression deformation of the root soil complex of grass and shrub vegetation,and negatively correlated with the shear strength.The compressibility of root soil complex of herbaceous vegetation(white clover and spot grass)is stronger than that of rootless soil,while the compressibility of root soil complex of shrub vegetation(Hua Kong mu)is weaker than that of rootless soil.The main reason is that the xylem in the roots of shrub vegetation is more developed than that of herbaceous vegetation,so it has a certain ability to resist deformation.(2)The shear strength of root soil complex of grass and shrub vegetation is larger than that of rootless soil,and its shear strength increases linearly with the increase of normal stress,indicating that the root soil complex still obeys the Mohr Coulomb strength failure criterion.Under the same level of root density,the permeability of root soil complex of grass and shrub vegetation is followed by Chinese fir,spot grass and white clover from large to small,that is,the permeability of root soil complex of shrub vegetation is greater than that of herb vegetation.(3)The safety factor of the slope after vegetation environment restoration is greater than that of the plain soil slope,and the vegetation root system can improve the safety and stability of the shallow slope to a certain extent.The slope safety factor decreases with the increase of slope gradient and height.The safety factor of vegetation slope under rainfall saturation condition is about 35%lower than that under drought condition.With the increase of slope gradient and height,the safety factor of vegetation slope decreases.When the slope height is controlled within 7m,the slope height should be appropriately reduced with the increase of slope gradient.In the actual project,it is suggested to cut the slope before ecological restoration,control the appropriate slope and height,and improve the overall stability of the slope.