Abstract
In the conventional approach of elastoplastic modeling, using the invariants of ordinary stresses and strain increments can not properly consider the effect of intermediate principal stress on the strength and dilatancy of soils. A previously introduced modeling approach using modified stress (tij) can express the strength and dilatancy behavior of normally consolidated clay under generalized three-dimensional stress conditions. It has been verified that this modified stress approach closely simulates soil behavior under monotonic loading conditions. To express stress induced anisotropy, a kinematic hardening (in the stress ratio space) model for clay using modified stress has been proposed, which over predicts volumetric strain and does not show stabilization of strain during cyclic loading. To rectify those problems the evolution rule of the rotational variable has been modified and a subloading surface has been introduced in the model proposed in this paper. The applicability of the proposed model on normally or overconsolidated clay under monotonic or cyclic loading conditions is verified using triaxial, true triaxial and torsional shear tests.
