Experiment and Numerical Simulation of Repeated Liquefaction-Consolidation of Sand

Abstract

Behaviors of a liquefied ground are influenced by many factors, such as density, confining stress, permeability, particle size and grading, etc. Among these factors, the density plays the most significant role. It is known that when subjected to cyclic loading under undrained condition, there exist three types of liquefaction behaviors, i.e., loose sand will fail directly towards zero mean effective stress without cyclic mobility; medium-dense sand will enter into a cyclic mobility before being completely liquefied; very dense sand, however, will not liquefy at all. In liquefaction analysis, it is important to distinguish these three types of liquefaction behaviors according to different densities. In this paper, firstly, a constitutive model proposed by the same authors is briefly introduced. Secondly, experimental results of shaking-table tests on saturated sandy ground with repeated liquefaction-consolidation process are presented. Then, a finite element-finite difference method (FE-FD) based on the constitutive model and two-phase field theory is conducted. Comparisons between the experiment and the numerical simulation show that the numerical simulation is capable of reproducing almost all main characteristics of the repeated liquefaction-consolidation of sandy grounds with different densities, such as the mechanical behavior pre- and during liquefaction, the settlement in post-liquefaction consolidation and the influence of density on the accumulation of excessive pore water pressure (EPWP) in repeated strong motions.