AN ELASTOPLASTIC CONSTITUTIVE MODEL FOR COARSE-GRAINED SOILS

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