Numerical Investigation of Stone Column Improved Ground for Mitigation of Liquefaction

Abstract

Installation of a stone column in loose soil is one of the robotics ground enhancement techniques that reduce the risk liquefaction and related ground deformation. However, the experimental investigation is costly and it is time-consuming to check the feasibility of this technique for the evaluation of ground subsidence and fluctuations in excess pore water pressure concerning different area ratios of a high modulus column. This paper presents a numerical investigation into shallow foundations underlain by a stone column as a liquefaction countermeasure. The Biot's consolidation equations are coupled with stress equilibrium equations in finite element modeling for cyclic loading conditions. The critical state model based on generalized plasticity theory was applied to model the nonlinear behavior of soil. The unknown displacement and pore pressure are evaluated using code written in FORTRAN 90. The granular column installation effect is also considered to predict displacements and excess pore pressure (EPP) at each time step. With the introduction of a granular column, considerable reductions were observed in displacements and EPP. The results underline the effectiveness of granular column installation as an effective measure in the mitigation of liquefaction.