| With the deterioration of the ecological environment,the ecological protection of green plants has been paid more and more attention.The control of soil and water loss by plant roots has also became a hot issue in multidisciplinary research.Slope ecological protection has the effect of restraining slope runoff and increasing rainfall infiltration,and the reinforcement effect of vegetation root can effectively improve the shear strength of slope shallow soil and thus affect the stability of slope.At present,soil ecological protection was commonly used in soil slope,and its effect in rainfall erosion and soil and water conservation was mainly considered.The influence of vegetation root on rainfall infiltration and shallow slope stability was rarely considered.The study of the strength characteristics and the permeability characteristics of the root-soil composite provides a theoretical basis for the analysis of shallow slope stability and slope ecological protection.Based on the collection of large amounts of data and field research,this paper studied the effect of the shear strength and permeability on the root-soil composite of ryegrass root,which led to the variation of the shallow stability under different rainfall conditions and different slope ratio conditions from the perspective of ecological slope protection mechanics and hydrology.The main contents and conclusions of the study are as follows:(1)The influence of the permeability coefficient of the root-soil composite with different content of ryegrass roots in different depths was studied through indoor variable head penetration test.The results showed that the permeability coefficient of the root-soil composite was higher than the soil sample without roots,and the smaller the soil depth,the higher the root content of vegetation,the higher the root content in the soil,the greater the increase of soil permeability coefficient.(2)Based on the laboratory direct shear tests of the root-soil composite sample containing ryegrass roots in natural and remoulded soil sample,the effect of shear strength of the root-soil composite with different depth and different content was studied.The results showed that the plant flocculent root system could significantly improve the cohesion of the root soil composite.The closer to the surface,the greater the content of the roots in root-soil composite samples was,and the stronger the cohesive force was.In the same vertical pressure condition,the shear strength of the root-soil composite had a good linear relationship with the root content of the root-soil composite,which was subject to the Mohr-Coulomb criterion;Due to the growth characteristics of plant roots,the flocculent roots and soil bite close,and remodeling soil was only the root and soil combined compaction,so compared to remodeling soil,undisturbed soil friction was greater.(3)Considering the effect of herbaceous plant roots on soil reinforcement and permeability change,the effects of rainfall,rainfall duration,slope slope ratio and other factors on the stability of vegetation protection slope were studied.The results of numerical simulation showed that the reinforcement effect of plant root system was more favorable to the stability of slope with the increase of slope slope rate,and the plant root reinforcement effect was more obvious when the slope self-stabilization ability got worse.The effect of plant root reinforcement on the early stage of rainfall was obvious,and when the slope soil was saturated,its effect was obviously weakened.Compared with the no plant slope,the safety factor of plant slope was relatively slow with the increase of rainfall duration. |
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