Typical Vegetation In Hot-dry Valley Of Jinsha River Study On The Influence Of Soil Stability

The hot and dry Jinsha River Valley is one of the areas in the Yangtze River basin with serious soil erosion.Soil erosion is a phenomenon of soil erosion caused by water flow,wind and other factors,which leads to the deterioration of land quality and ecological environment.Soil erosion will cause serious harm to society,economy and environment.Anchorage of soil by vegetation roots is an effective way to control soil erosion.Studying the mechanical properties of vegetation root-soil complex and roots has important theoretical and application value for soil reinforcement.Based on the interdisciplinary basic research of soil mechanics,elasticity mechanics,material mechanics,soil and water conservation,forest ecology,mathematics and other disciplines,this study analyzed the influence of different vegetation types on soil shear properties.It provides theoretical support for the research of preventing and controlling soil erosion,soil erosion and other natural disasters in this area,and provides technical assurance and construction measures for the current soil and water conservation projects.In this paper,through direct shear test of root-soil complex,indoor single root tensile test and soil physical and chemical properties measurement,to explore the effects of different vegetation types of shear strength parameters,soil physical and chemical properties and root tensile properties on soil stability.The main research achievements are as follows:1.For vegetation in the same soil environment,its shear strength increases with the increase of vertical pressure,and there are significant differences between different vegetation types,and there are significant differences between the shear strength parameters of different vegetation types.By fitting the relationship between cohesion,internal friction Angle and soil depth of each vegetation type,the variation law of shear strength with depth of 0-30 cm soil depth of different vegetation types was obtained.2.For vegetation in different soil environments,the relationship between water content,soil bulk density,pH value,total phosphorus,total potassium and organic matter content and internal friction Angle and cohesion was analyzed.Pearson correlation analysis was used to analyze the correlation among these influencing factors.Finally,principal component analysis revealed that the primary and secondary order affecting the shear properties of the root soil complex was as follows: Water content > pH value,total phosphorus and organic matter content > bulk density and total potassium.Then,using the weight of each influencing factor of principal component analysis,the comprehensive score of the shear strength of root soil complex of different vegetation types was calculated to evaluate the shear strength of different soil depth of vegetation.3.The root tensile strength,tensile strength,elongation and elastic modulus were obtained through the single root tensile test,and the change rule of these root tensile properties with root diameter was analyzed.For roots of different vegetation types,the tensile strength increased with the increase of root diameter,while the tensile strength,elongation and elastic modulus decreased with the increase of root diameter.The effect of typical vegetation roots on soil stability was obtained by analyzing the tensile properties of roots and the enhancement of the shear strength of root soil complex.