The Study Of Shear Properties Of Five Kinds Of Soil And Caragana Roots Composite

The article studied4main types soil, Sand (silty soil sand, fine-grained sand), silt (low liquid limit silt), clay (low liquid limit clay) and the sandstone weathered soil that lied on the central region of Inner Mongolia and3-4years old Caragana microphylla Lam (the typical plant can conserve soil and water) relationship on the shear characteristics, residual shear characteristics and the friction characteristics of root-soil interface of5kinds of root-soil composite. The test used the shear test way in laboratory. The result showed that:The shear displacement of4types plain soil and the root-soil composite were both with the increase of shear stress the curve for hardening. In the main distribution layer (root depth of1.5m),4types of soil and root-soil composite body’s ability to resist shear deformation followed by clay> silt> sandstone weathered soil> sand, and fine-grained sand> silty soil sand.In the soil dry density was1.45g/cm3, soil saturation was25%,40%,55%,70%and85%,4types of root-soil composite shear strength and residual shear strength were greater than the corresponding plain soil. Plain soil and root-soil composite of Sand, silt, sandstone weathered soil shear strength, residual shear strength were both with soil saturation increasing showing a decreasing trend after the first increase; but the peak strength of all kinds of soil had a different soil saturation, While the clay decreased with the increase of soil saturation.4types of soil and root-soil composite cohesion, residual cohesion changed consistent with the above law, Angle of internal friction and the residual friction angle decreased with increasing soil saturation.Root depth of1.5m, the improve effectiveness of the residual strength was greater than the shear strength, that was relevant with bending strength,elastic-plastic deformation characteristics of roots and root-soil interface friction characteristics. With the increase of soil saturation, represented by caragana plant roots to improve soil shear strength and residual strength was the low saturation gater than high saturation, and Effects as root to improve soil was80cm depth better than150cm. Plant roots to improve the effectiveness of coarse-grained soil strength was greater than the fine-grained soil. Growth of cohesion and residual cohesion was similar with the above law, but internal friction angle, residual internal friction angle compared witn prime1soil was no significant rule. 5kinds of root-soil interface cohesion and residual value was less than the corresponding cohesion soil-soil interface, and cohesion was less than the residual cohesion. The coefficient of friction was the root-soil interface greater than the soil-soil interface, and the residual friction coefficient greater than the coefficient of friction...