Intergranular-strain elastic model for recent stress history effects on clay

Abstract

An elastic model is proposed to enhance elastoplastic models for the non-linear stiffness variations at small strains and the recent stress history effects of clay. This model relies on the intergranular strain concept that is introduced by Niemunis and Herle (1997). The intergranular strain model achieves great success in modeling the recent stress history effects, but its application has mainly be restricted in augmenting hypoplastic models. This work proposes a new interpolation rule for directional stiffness to facilitate the incorporation of the intergranular strain model into the framework of elastoplasticity. The correlations between intergranular strain parameters and the reference strain of well-established modulus degradation curves are obtained to ease the model calibration. The intergranular strain elastic model is used to enhance a bounding surface plasticity model, and the performance of the augmented model is examined against experimental observations on compressible, lightly-overconsolidated Chicago clay. The comparison of the model against experimental evidence shows that the proposed elastic model is capable of enhancing existing elastoplastic models for replicating the effects of recent stress history on the small-strain behavior of clay.