Masoud Oulapour - Assistant Professor, Faculty of Civil Engineering, Shahid Chamran University of Ahvaz
Hossein Mohmedi kartalaei - M.Sc. student of geotechnics, Shahid Chamran University of Ahvaz

Liquefaction of sandy soils d uring earthquakes is a cause for concern as it may lead to disastrous consequences, s uch as significant structural damage and loss of life. Considerable advances hav e been made in recent years in the area of num erical analysis of soil liquefaction. these phenomenon in soils subjected to dynamic lo ading has received considerable attention since the experiences in Japan and Alaska during the mid 1960s.In this paper, the behavior of sand due to earthquake-induced liquefaction by means of finite element method and th e use of the two-surface constitutive model develop ed by Poorooshasb and Pietruszcza k (1985) for numerical simulation. Then soil defor mation is investigated during earthq uake and after soil liquefaction. From the results of this model it can be seen that t he major deformation of the soil without applyi ng the overhead in the horizontal d irection, the maximum is at ground level and continues deep in the nonlinear and descending direction, but the vertical deformation, w ich is very low, is only 2 meters E arth s surface is observed. It is worth noting that such a model is valid to the soils without overload and prone to being liquefaction.

liquefaction, N umerical simulation, Finite Element, Soil Deformati on