A. Janalizadeh - Department of Civil Engineering, University of Mazandaran, Babol, PO Box ۴۸۴, Iran.
S.B. Hoseinian - University of Mazandaran, Department of Civil Engineering, Babol, PO Box ۴۸۴, Iran.

Liquefaction of loose water saturated soils is a consequence of the build up of large excess pore pressures due to partially undrained deformation, leading to a relatively small undrained shear strength compared to the shear strength for drained behaviour. It has been responsible for the failure of many geotechnical structures.The main purpose of this research work is the numerical simulation of such liquefaction. It involves the development of an isotropic constitutive soil model for monotonic deformation up to large flow. The model uses the void ratio as a state parameter, so the same material parameters can be used for all possible void ratios. The numerical implementation of this constitutive model in a finite element program incorporates an incremental formulation of the large deformation theory. The finite element program is implemented in the Fortran "90" numerical environment.In the current numerical studies, the hypothesis of a rate independent unique "steady state"is used. Here it is called the "ultimate" state to be consistent with the word "ultimate" shear strength used by [1]. It has been shown that this ultimate state does not enable to distinguish between liquefiable and nonliquefiable soils

Liquefaction, undrained deformation, numerical modelling