Experimental Research On Shear Strength And Loess Permeability Of The Intact Loess Joints And Engineering Application

The joints in loess are important factors that affect the loess engineering properties. To recognize the strength characteristics and the infiltration law in unsaturated loess field on the consideration of loess joints is one of the basic works of the study in Loess disaster prevention, loess characteristic and geotechnical problems related in loess area. The paper has made some research work about the strength characteristics and the infiltration law in unsaturated loess field on the consideration of loess joints.The experiment obtains the surface contours, the density and the water content to the loess joints intensity characteristic influence. Reveals the rule that loess joints surface contours influence the value of parameter c andφof resistance sheare strength. In the same water content and dry weight density situation, the cohesive force c's value of rough surface joints is greatter than smooth surface joints, but the change of the angle of internal frictionφ's value of the loess joints is small, explained that the loess joints' surface contours has to affect the value of joints cohesive force c greatly, but to affect the value of the angle of internal frictionφsmally; the dry weight density affects the loess joints cohesive force c's value greatly, but affects the angle of internal friction cp's value smally. When the water content of test specimen is in a certain scope, with the increase of water content, loess joints'angle of internal friction changes showed a quadratic relationship; When the test specimen water content increase quickly, the experiment obtains test specimen shear strength to have slightly increases, because partial soil bodies on the loess joints surface remodeled under the normal pressure, the failure plane already was not the original joints plane, the shear strength of the remodel soil caused the shear strength of the loess joints enlarge in the test. The experiment for the infiltration law in unsaturated loess field on the consideration of loess joints analyses the influence of the different joints position qualitatively.Through the laboratory test qualitative analysis rainfall to the soil body permeable influence, the influence on loess permeability of closed joint can not be considered. Along with joint width increase, the joint tends to be obvious gradually to the soil body permeability; The joint becomes the superiority transfusion surface, has increased moisture content seepage in the soil body, and the joint also increases the both sides soil body's influence width along with the joint width increases, joint influence width along with the soil body depth to reduce gradually; The soil body dry weight density is smaller, the soil body permeability is bigger, the joint takes the superiority transfusion surface to be also more obvious, and joint also has to the both sides soil body's influence width increases.Based on the study above, using finite element method, analysis the influence law of the thickness of the overlaying soil, water content of the loess and loess joints in stress distribution in loess caves and the stability of the loess cave.