Ahad Ouria - Assistant Professor, University of Mohaghegh Ardabili, Iran
Stefan van Baars - Professor, Faculté des Sciences, de la Technologie et de la Communication, University of Luxamburg.

In this paper a rate dependent viscoplastic constitutive model is presented for soft soils. This model is based on the long-term creep tests under hydro static stress conditions. In this model the viscosity considered as shear stress relaxation; therefore viscosity affects only the shear stress or strain. Mohr-Coulomb failure criterion is employed to plastic calculations. Shear modulus is considered as stress, strain and time dependent. Time dependency of the shear modulus is related to the occurred viscoplastic deformations. Numerical calculations show the applicability of the presented model for viscoplastic calculations.

Constitutive model, Creep, Soft soil, Shear Modulus