MODELISATION NUMERIQUE DU COMPORTEMENT A LA LIQUEFACTION DES SOLS HETEROGENES

Abstract

IV Abstract This work studies one of the most important and complex phenomena of soil dynamics that is the liquefaction. A bibliographical study of the phenomenon, mechanisms and theoretical approaches used in the estimation of liquefaction potential are detailed. Our objective is to carry out a parametric study of the factors that influence it, especially the fines content and density state. According to previous research, the presence of fines can either increase or decrease susceptibility to liquefaction and numerical modeling was performed using the Plaxis software to validate the results of the experimentation. The program of experimentation is composed of a large number of automatic triaxial compression tests carried out on silty sand of Kharouba (Mostaganem), which is separated in order to reconstitute studied sample. An interval of 0% to 40% in fine content constitutes the sand-silt mixtures forming the samples of the studied ground and two values of relative density are used, namely 15% and 55%. The simulation performed under a code named Plaxis using the same characteristics as those of the experimental study in order to confront the results of the experimentation with those of simulation. The objective of this work is to develop a numerical model able to simulate the behavior of heterogeneous soils saturated undrained condition relative to the susceptibility of these soils to liquefaction by introducing new parameters which are the equivalent intergranular void ratio and the equivalent relative density. The results of this research show firstly an insufficiency and deviation from Chinese criteria that are a reference in the field of liquefaction and secondly that heterogeneous soils are likely to liquefy in a fines content of up to 30%.