AN ELASTOPLASTIC-VISCOPLASTIC BOUNDING SURFACE MODEL FOR ISOTROPIC COHESIVE SOILS ---INTERNATIONAL CONFERENCE ON RHEOLOGY AND SOIL MECHANICS, 12-16 SEPTEMBER 1988, COVENTRY, UK

A generalized three-dimensional constitutive model for isotropic cohesive soils, based on the concept of the bounding surface in stress space, is developed within the framework of coupled elastoplasticity-viscoplasticity and critical state soil mechanics. The prominent feature of the bounding surface concept is the fact that inelastic deformations can occur for stress points located within the bounding surface. The consideration of viscoplastic characteristics sets the current model apart from previous bounding surface formulations for soils and introduces rate and time effects. The coupling between plasticity and viscoplasticity for stress states within the bounding surface differentiates the present work from the classical formulation of pure viscoplasticity (no coupling), or from formulations involving plasticity and viscoplasticity with a yield surface (coupling only for states on the yield surface). Incremental constitutive relations applicable to isotropic cohesive soils are developed. A minimum number of parameters are introduced and the predictive capabilities of the model are evaluated.(a) for the covering abstract of this conference see IRRD 818664.