Assessment of Soil Liquefaction Resistance by Finite Element Approach

Abstract

Soil liquefaction is the source of several major damages during earthquakes on the material and human level. Liquefaction of soil occurs under dynamic or cyclic loading, due to which the soil loses its strength. A soil deposit subjected to seismic loading can be viewed as a binary system: it will either liquefy or not liquefy. Generalized linear models are versatile tools for predicting the response of a binary system and hence potentially applicable to liquefaction prediction. In the present study, a numerical procedure based on finite element technique is presented for evaluating the characteristics of soil liquefaction and the foundation response under seismic loading. The relative density of soil is an important parameter in prediction of liquefaction. However, this property varies from place to place with the density and nature of soil. Therefore, a double layered soil profile is used to model the change in relative density of soil with depth. A constitutive elasto-plastic model with dynamic loading is considered to study the phenomenon of liquefaction. The approach is presented through the simulation of five major earthquake data. The different parameters of simplified method as proposed by Seed and Idriss have been measured for the given field conditions, with varying magnitudes of earthquake and horizontal ground acceleration. The factor of safety has been calculated and is being used to denote the occurrence of liquefaction for all the cases of soil strata considered. Parametric studies are carried out considering different ranges of relative density of sand and earthquake magnitudes, and the corresponding factors of safety are proposed for the same.