The Study Of Shear Properties Of Two Kinds Of Soil And Caragana Microphylla Roots Composite

Based on the principle of soil,we adopt indoor direct shear test to study the geotechnical characteristics(shear resistance,residual shear resistance)of the bifurcated root-soil complex of Caragana microphylla Lam in two kinds of Soil type,root diameter and shear direction.The experiment results show:The shear stress of silty sandy root-soil complex and low liquid limit silty root-soil complex show hardening curve with the increase of strain.The relationship between the same shear strength and residual shear strength of the same type of soil is:straight root>bifurcation root-soil complex>plain soil.At the soil burial depth of 0.8m the lifting effect of bifurcated roots on the shear strength is better than that at the soil burial depth of 1.5m.Within 1.5m of the buried depth of the root system,the resistance to shear deformation of the undisturbed soil and the root-soil complex with two root diameters(0.75mm and 3.75mm)is successively as follows:coarser straight root>coarser bifurcation root>thinner straight root>finer bifurcation root>undisturbed soil.The relationship between the adhesion and residual adhesion of the root-soil complex with straight roots and two diameters is the same as that of the root-soil complex with bifurcated roots.The relationship between cohesion and residual cohesion of the rhizosphere complex with the same root diameter is:straight root>bifurcation root.No obvious change rule of internal friction Angle and residual internal friction Angle are found.The residual shear modulus of bifurcated roots and straight roots composed of thicker(3.75mm)and thinner(0.75mm)roots increased with the increase of the vertical load,and the shear modulus of each group of samples was greater than the residual shear modulus.Under two kinds of shear direction,bifurcate spikes-composite soil shear strength,residual shear strength,and vertical load is linearly related to the size of the two relations are the positive shear>lateral shear,root soil cohesion,residual cohesion were greater than earth,and show the positive shear>lateral shear.There is no obvious rule for the Angle of internal friction and the Angle of residual internal friction.