A Johari - Assistant Professor, Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran
J Rezvani Pour - Ms Candidate of Earthquake Engineering, Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran

The prediction of liquefaction and resulting displacements is a major concern for earth structures locatedin regions of moderate to high seismicity. Several efforts have been published in literature especiallyduring recent years for developing model to predict this phenomenon. In this paper an elasto-plasticconstitutive model is used that simulates the static liquefaction response of loose sands under monotonicloading in a relatively uncomplicated manner. The model is based on the characteristic behavior of thesoil skeleton. It has several key futures, including a hyperbolic relationship between stress ratio andplastic shear strain and a flow rule for estimating plastic volumetric strain from plastic shear strain.When the soil is nonlinear elastic and/or elasto-plastic, the equivalent constitutive matrix is no longerconstant, but varies with stress and/or strain. It therefore changes during a finite element analysis.Consequently, a solution strategy is required that can account for this changing material behavior. Themodified Newton-Raphson method is used to consider the effect of changing material behavior in thisresearch. The result indicated that the model and developed procedure can predict the pattern ofliquefaction correctly. Based on the result, liquefaction propagates downward in effect on surfaceloading.

Elasto-plastic, Static liquefaction, Monotonic loading, Modified Newton-Raphson method