Elastic-Visco-Plastic Relations of Soils

Based on laboratory creep tests of soils, the method for analyzing the elastic-visco-plastic stress-strain relations are presented in this paper. The given method has been applied to analyze the laboratory shear creep testing results of three different kinds of soils, i.e., the Wuhan clay, Shanghai clay and Zhengzhou loess. The results of analysis indicated that fair relations between the elastic-visco-plastic stress and strain can be obtained. The visco-elastic and visco-plastic stress and strain relations for these soils can be described by linear and hyperbolic functions respectively.The yielding shear stresses can be determined for all these soils from the creep tests. The soils behave like a visco-elastic material when the shear stresses in the soils are lower than the value of yielding shear stress and behave like a visco-plastic material while the shear stresses in the soils are higher than that of the yielding shear stress. The method of determining the ultimate shear stress for the soils mentioned above are also given in this paper. Comparison was made between the values of the ultimate shear stresses obtained by the given method with that from the laboratory creep testing results.