Study On The Availability Of Four Kinds Of Plant Roots To Improve Shear Strength

Based on the principle of botany,material mechanics,soil mechanics and plastoelasticity, investigate the the influence on shear behavior of the root-soil composite and shear strength of the roots of four typical plants which can fix the soil in Complex Erosion by Wind and Water Area by direct shear tests and vane shear tests. Follow the study of two growth period of four kinds of root-soil composite by direct shear tests. The results indicate that the shear behavior of the root-soil composite is different in two growth period. The shear strength of root-soil composite (Sabina valgaris Ant. , Salix psammophila C.Wang et Ch.Y.Yang , Caragana microphylla Lam. , Artemisia sphaerocephala Krasch.) are more intensive than pure soil within the buried depth of 1.5m(25kPa). With the same root diameter (1.25mm), in early growth period, the order of cohesion of these composites at the depth of 1.5m(25kPa) from the earth's surface is Salix ossammophilia C.Wang et Ch.Y.Yang > Sabina valgaris Ant. > Caragana mierophylla Lam. > Artemisia sphaerocephala Krasch. .In vigorous growth period, the range of growth rate of cohesion between 4.6%-46.23%, the order of cohesion is Caragana mierophylla Lam. > Sabina valgaris Ant. > Salix ossammophilia C.Wang et Ch.Y.Yang > Artemisia sphaerocephala Krasch.; Within the range of one level away from the representative standard root diameter, the shear strengths of the four types of root-soil composites increase differently with the increase of the root diameter. The internal friction angle has a linear decrease with the increase of soil moisture content, and the cohesion of the root-soil composites has a trend of the first increase then in lower; Within the increase of soil density, the cohesion of the root-soil composites has a increase trend of power exponent, the internal friction angle has no obvious change. When its cross-sectional area of the roots in the sample is fixed, the shear strength of the root-soil composite of Caragana microphylla Lam increase with the increase of the number of the roots.When the roots have different directions, the difference between the shear strengths of different Caragana microphylla composites is 45°reverse root distribution> 90°vertical root distribution > 45°lateral root distribution> 45°forward root distribution.