Numerical Simulation of Earthen Embankment Resting on Liquefiable Soil and Remediation Using Stone Columns

Abstract

This study aims to predict the effect of liquefaction on an embankment resting on liquefiable foundation soil. A numerical model has been simulated in PLAXIS 2D with plane strain idealization. An effective stress–based elastoplastic UBC3D-PLM model has been used to represent the constitutive behavior of foundation sandy soil. The embankment soil has been modeled using the Mohr–Coulomb material model. Initially, the pore pressure and settlement response have been derived for the model without a stone column. The top surface of the loose foundation soil experiences excessive heaving near the embankment toe toward the free surface beside the embankment on either side. Subsequently, a parametric study has been conducted on the mitigation of liquefaction beneath the embankment and liquefaction-induced settlement considering stone columns as a mitigation measure. Stone columns have been modeled assuming equivalent plane strips by considering the equivalent permeability and bulk modulus of stone columns. The efficacy of stone columns in controlling the heaving has also been revealed from this study in addition to the reduction in excess pore pressure beneath the embankment toe and the settlement of the embankment. The parametric study has also investigated the effect of diameter and spacing of the stone column. It has been observed in the case of cyclic loading input that with increasing the amplitude of loading, the effectiveness of stone columns reduces, and this leads to an increase in the crest settlement. Moreover, a seismic study of the embankment model has been carried out for 10 different ground motions to examine the effect of the stone column. The study reveals that for moderate-intensity ground motions, the stone column shows an effective mitigation of excess pore pressure near the embankment toe along with a reduction of embankment crest settlement.