Numerical Analysis of Earth Embankment Resting on Liquefiable Soil and Remedial Measures

Liquefaction-induced ground displacements resulting from earthquake shaking are a major cause of damage to earth structures comprised of, or underlain by, loose saturated granular soils. The present paper describes the results of numerical modeling of an embankment founded on loose liquefiable deposit using PLAXIS three-dimensional finite-element software. Acceleration base-input excitation of the El Centro earthquake has been applied to the model monitoring the displacements, liquefaction potential, and excess pore pressures (EPPs). A modified nonassociative plastic-potential function depending on the Drucker-Prager criterion is used to maintain the coaxiality of stress strain in the deviator plane for a stress path initiated from an isotropic line. The soil-densification rule is also added to predict more realistic EPPs in seismic loading. The countermeasures considered are densification of the sand layer by compaction and sheet pile enclosure. The dynamic behavior of the used embankment-foundation and liquefaction countermeasure systems are also presented. The sheet pile measure is effective in controlling the displacements but has marginal effect on EPP. The soil-column countermeasure was the most effective case in limiting the development of EPPs and displacement beneath the embankment. The results of this study show that numerical simulation of earthquake effects on embankments with liquefiable foundations with and without remedial measures is possible using data from conventional laboratory tests and a verified numerical procedure.