Numerical Modeling of Liquefaction in Layered and Silt Inter Layered Sands

In this paper, the pyhsical model tests which were carried out in the laboratory on uniform sand columns, silt inter layered sand columns and two layered sand columns deposited at various relative densities and subjected to different input accelerations are numerically modelled. The numerical analyses are performed by using Towhata-Iai liquefaction model in a finite element program called DIANA and the excess pore water pressures computed from the numerical analyses are compared with the experimental results. The numerical analyses have shown that the development of excess pore water pressures is highly influenced by the relative density of the sand and the presence of a less permable soil layer within the sand deposit. The numerical modeling of silt interlayered sand tests showed that there is an abrupt increase in the ru values below the silt seam demonstrating the accumulation of pore water pressures due to the presence of silt layer. The results of the numerical analyses also revealed that a constitutive model coupled with a ground water flow analysis must be used to simulate the generation of excess pore water pressures especially in layered sand deposits