A numerical study on liquefaction induced settlements by using PM4Sand model

Abstract

The destructive effects of earthquakes negatively affect many people's lives and cause a large number of lives and property losses. One of the most crucial factors that increase the destructive effects and structural damages of earthquakes is the deformations in the soil layers during strong ground motion. Especially liquefaction due to sudden increase in pore water pressure during strong ground motion in saturated sandy soils causes large deformations in the soil layers; hence leads to severe damage to the structures. Therefore, it is necessary to determine the liquefaction-induced deformations and settlements in the soil layers with high liquefaction potential. Following this purpose, three different two-dimensional fully saturated soil profiles with 35, 55, 75 % relative densities were created and carried out by using different strong ground motions for estimation of liquefaction-induced free field settlements. The finite element code "Plaxis 2D" and constitutive model "PM4Sand" were used in the analysis. The results of finite element (FE) analyses were compared with semi-empirical methods in the literature. The liquefaction state observed with pore pressure ratio (Ru) and safety factor (FS) is similar in numerical and empirical methods. The FE analyses have shown that the evaluation of free-field, liquefaction-induced settlements obtained from PM4Sand-Model have considerably lower settlement values than the semi-empirical methods. However, the semi-empirical method suggested by Cetin et al. (2009) and numerical analyses gave quite similar settlement results to each other. Moreover, there is no direct relationship between the liquefaction-induced settlements and the earthquake source properties in the numerical method. However, this is different for semi-empirical methods, and there is a relationship between strong ground motion features and liquefaction-induced settlements.