The Elastoplastic Characteristics Of K₀-Consolidated Unstaturated Loess

In this paper an initial density-dependent elastoplastic model is proposed for unsaturated loess with initially stress-induced anisotropy. The hardening axis in the presented model is between the axes of the cam-clay model and the Sekiguchi-Ohita model. A transformed stress based on the SMP criterion is used for making the model become a reasonable three-dimensional model. The initial anisotropy of loess is under consideration by using η*. The influences of suction on the mechanical behavior of unsaturated loess are taken into account in the model by using a parameter named suction stress σ₀(s) . The initial density dependency of the unsaturated loess behavior is modelled by establishing experimental relationships between the initial density and the corresponding yield stress and thereby between the initial density and the slope of normal compression line, which make the model suited to predict the mechanical behavior of unsaturated soil for various initial density. The proposed model needs few material parameters, which can be easily determined from the results of ordinary tests. It can predict the stress-strain-strength behavior of unsaturated soil under the conditions of three-dimensional stresses and constant or variable suction.The deformation behavior and wetting characteristics of unsaturated loess are study by modify triaxial apparatus, and the main alterations are axis pressure and pore pressure measurement systems. In the tests, the natural specimen is K₀-consolidated firstly, and then sheared, wetted, sheared to destruction.