A critical state subloading surface model of sands with shear hardening

Abstract

Based on the framework of critical state soil mechanics, a subloading surface plastic model for sand, being applicable to cyclic loading, was proposed. The model can be used to describe strain softening behaviour of sand under monotonic loading when the similarity-ratio equals to unity. The characteristics of the model are as follows: 1) A reverse bullet-shaped yield surface is adopted to ensure accurate prediction of the behavior of sand, instead of bullet-shaped or elliptical yield surface in Cam-Clay model. 2) No unique relationship between void ratio and the mean normal stress for sand prevents the direct coupling of yield surface size to void ratio, so incremental deviatoric strain hardening rule is used. 3) The model combines the concept of state-dependent dilatancy by incorporating state parameter in Rowe’s stress dilatancy equation, which accounts for the dependence of dilatancy on the stress state and the material internal state. A single set of model constants, which is calibrated, can simulate stress—strain response under different initial void ratios and different confine pressures. The model is validated true by comparing predicted results with experimental results under monotonic and cyclic loading conditions.

Keywords

shear hardening / critical state / subloading surface / state parameter / dilatancy