AN ELASTOPLASTIC CONSTITUTIVE MODEL FOR COARSE-GRAINED SOILS

Abstract

This paper developed a new elastoplastic model for coarse-grained soils. Plasticpotential surface was established by solving a differential dilatancy equation, which is obtained viathe triaxial test results. This model obeys a non-associated flow rule; therefore, the yield surface isnot consistent with the plastic potential surface. Expression of the yield surface was establishedsimilar to the plastic potential surface, but its shape is influenced not only by the stress ratio η, butthe mean stress p . A unified hardening parameter that is independent of stress path is adopted, sothat negative dilatancy and positive dilatancy properties of coarse-grained soils could both bedescribed. In this research, elastoplastic formula of the proposed model is deduced. This modelwas also evaluated with several groups of test results under different stress paths (i.e. conventionaltriaxial tests, constant mean stress test and constant stress ratio test, etc.). Results showed thatmodel predictions agree well with the test results.