Study on Mechanical Properties of Soil Stabilization by Different Vegetation Roots on High Steep Slope

Abstract

The tensile and shear properties of plant roots are important factors that determine their slope protection and are also direct indicators for evaluating plant roots for slope protection. In order to explore the soil-fixing properties of root system and root–soil composite of Indigofera amblyantha and Cassia bicapsularis, the high and steep slope of Zhaofu quarry in Wudang District of Guiyang City was taken as the research background. The effects of root diameter, tree species, root water content and normal pressure on the tensile properties of single root, direct shear friction of root system and shear properties of root–soil composite were investigated by an indoor mechanical test and a direct shear friction test. Results showed that under saturated water content, the tensile strength of C. longifolia decreased, and the tensile strength of C. bifolia also decreased. With the increase in water content from 10.3% to 22.3%, the friction strength of the root–soil interface increased gradually, and the friction strength of root–soil interface of Cassia bicapsularis was greater than that of Cassia longifolia. With the increase in root diameter, the root–soil interfacial friction strength of the two shrubs increased slightly. The normal pressure also increases the density of the soil, so that the roots give full play to the reinforcement effect. The greater the normal pressure, the greater the shear strength of the root–soil composite. When the water content increased from 10.3% to 22.3%, the shear strength of the two-shrub root–soil composites increased first and then decreased gradually, reaching the maximum at 14.3%, followed by the shear strength at 10.3%, reaching the minimum at 22.3%.