Constitutive model and implicit return-mapping algorithm for the simulation of the mechanical behavior of soil

In this contribution, on the basis of the hierarchical approach (Desai, 1980), a constitutive model for the soil response in the elastoplastic range has been developed. An unconditionally stable, implicit Euler backward algorithm for the integration of the constitutive relations is also presented in detail. The formulation is applicable to a wide range of elastoplastic models that occur in soil mechanics. The emphasis has been placed on presenting the particular model characteristics, simulation of soil hardening and softening response and the establishment of model nonassociativity. All model parameters have been associated with quantities that can be determined from the experimental process ensuring thus the physical meaning of the parameters.