Kinematic hardening plasticity formulation of small strain behaviour of soils

An objective of this paper is to demonstrate that the small strain model de veloped by the authors can be incorporated into the conventional kinematic hardening plasticity framework to predict pre-failure deformations. The con stitutive model described in this paper is constituted by three elliptical yield surfaces in triaxial stress space. Two inner surfaces are rotated ell ipses of the same shape, representing the boundaries of the linear elastic and small strain regions, while the third surface is the modified Cam clay large-scale yield surface. Within the linear elastic region, the soil behav iour is elastic with cross-coupling between the shear and volumetric stress -strain components. Within the small strain region, the soil behaviour is e lasto-plastic, described by the kinematic hardening rule with an infinite n umber of loading surfaces defined by the incremental energy criterion. With in the large-scale yield surface, the soil behaviour is elasto-plastic, des cribed by kinematic and isotropic hardening of the small strain region boun dary. Since the yield surfaces have different shapes, the uniqueness of the plastic loading condition imposes a restriction on the ratio between their semi-diameters. The model requires 12 parameters, which can be determined from a single consolidated undrained triaxial compression test. Copyright ( C) 2000 John Wiley & Sons, Ltd.