UH model for soils and its extention

Based on the relationship between the current yield surface and the reference yield surface, the UH model, called the three-dimensional unified hardening model for overconsolidated clays, has been proposed. The key feature of the UH model is adoption of a unified hardening parameter that is independent of stress paths. To evaluate the potential peak stress ratio in overconsolidated clays, a parabolic Hvorslev envelope rather than a straight line is adopted to modify the UH model. This modification leads to more realistic predictions on highly overconsolidated clays than with a straight line in the original UH model, and is consistent with critical state soil mechanics wherein the higher peak stress ratio shown in overconsolidated clays is a result of dilatancy rather than cohesion. The UH model has been developed and extended, and now it can consider the influence of anisotropy, suction, temperature, etc. The Generalized Non-linear Strength Theory (GNST) has been proposed based on the test date of frictional material and previous research achievements in this field. It describes non-linear strength properties on the π-plane and the meridian plane using a unified formula. Through the transformed stress space based on the GNST, the combination of the GNST and the UH model using p and q as stress parameters can be realized simply and rationally in three-dimensional stress state.