Study On The Effect Of Herbaceous Root System On Loess Slopes

Taking vegetated loess landslide area of Dongzhiyuan in Qingyang City of Gansu Province as the research object,this paper explores the mechanism of herb slope protection and soil consolidation,and establishes a theoretical model of herb root system for slope reinforcement.The research results can provide theoretical guidance for the practical application of vegetation slope protection engineering,and provide a basis for the quantitative calculation of the contribution of herb roots on loess slope.Firstly,the distribution characteristics of Bermudagrass in the slope were obtained through field investigation and sampling.After rainfall,bermudagrass can improve the water content in the shallow slope,and its influence degree gradually weakens with the increase of soil depth.Secondly,the shear strength and permeability of bermudagrass complex under different root content,water content and root stress were discussed by direct shear test.When the vertical pressure is 20KPa,the peak shear strength of the root sample is slightly lower than that of the plain soil sample;when the vertical pressure increases gradually,the root reinforcement effect is gradually reflected.The root content under the maximum shear strength of the root soil composite sample under a certain vertical pressure is defined as the optimal root content,and there is an optimal root content in the test process,which makes the peak shear strength of the root soil composite The optimal root system content has a strong correlation with the vertical pressure of the sample,but has no correlation with the moisture content of the sample.When the root content is constant,the cohesion and internal friction angle decrease with the increase of the water content of the root soil composite.When the sample is near the optimal water content,the shear strength of the sample with the optimal root content under different vertical pressures increases the maximum value of 46.98%;when the water content of the root soil composite is determined,the shear strength increases with the increase of the root content,The results show that the cohesion of root soil composite increases first and then decreases,and reaches the maximum at 0.6%,while the shear strength of root soil composite increases the most at 0.9%,and the change of root internal friction angle is small.Then,through the self-made indoor slope rainfall model device,to explore and simulate the rainfall erosion law and landslide evolution process of loess slope in the presence of plants.Finally,the mechanical mechanism of herb root system is analyzed and simplified,and the mechanical expression of soil to root system,the anchoring effect of soil around root system and the friction force on contact surface are obtained under certain soil depth.The friction coefficient of contact surface between root system and surrounding soil is determined by comprehensive?_x value method,which provides a theoretical basis for the correct calculation of herb root system for slope protection on foundation.