Abstract
A constitutive model of natural soft clay with strain softening, which is an important feature of overconsolidated clay, has been developed based on the concept of elasto-plasticity with memory. A new stress history tensor, which denotes a memory of stress with respect to strain, has been introduced by use of a strain measure. The stress history tensor is effective for discribing the deformation feature of frictional materials with strain softening. By using this stress history tensor, we extend the elasto-plasticity theory of overconsolidated clays previously proposed by Oka et al. The proposed model is capable of describing the strain-hardening and strain-softening behavior of natural soft clays in the overconsolidated region, and was applied to the triaxial drained and undrained behavior of a Champlain sea clay from eastern Canada. The comparison between volumetric and axial strain responses of experiment and simulation shows good agreement.
