Prediction of Permanent Deformations of Unbound Granular Materials in Low Traffic Pavements

ABSTRACT Permanent deformations of unbound granular layers and soils, caused by unfavourable moisture conditions, are one of the most common mechanisms of deterioration of low traffic pavements, with unbound granular bases. The paper presents permanent deformation models, developed by LCPC and by the University of Limoges, for the prediction of permanent deformations of unbound granular materials: a simple empirical model and two elastoplasticity based models for cyclic loading: one of them is based on the time independent plasticity with kinematic hardening, and the second one on the shakedown theory. The model parameters have been determined with cyclic triaxial tests performed on a granular base course material, at different moisture contents. An application of the models to finite element calculation of permanent deformations in a pavement structure is presented.