Numerical Simulation of Dynamic Behavior of Geofoam Embankment

Abstract

Geofoam is gaining in popularity as a lightweight alternative to soil for construction of embankments. However, its properties are significantly different from those of soil, and the dynamic behavior of the embankment is affected by the presence of geofoam. Two-dimensional numerical modeling of a simple embankment was performed to quantify the effect of geofoam on the dynamic behavior of the embankment. The dynamic responses of three embankments–-one constructed entirely of soil, one constructed entirely of geofoam, and one constructed of geofoam with a soil veneer–-were simulated. Regarding surface shaking, accelerations on the surface of the geofoam embankments were higher than those on the surface of the soil embankment. Regarding liquefaction, cyclic stress ratios of subgrade soils beneath the geofoam embankment were higher than those beneath the soil embankment, primarily because of the reduced effective stress caused by the use of geofoam instead of soil. Finally, factors of safety against interblock slippage calculated within a geofoam embankment indicate that earthquake-induced interblock sliding is more likely near the center and top of the embankment. These observations indicate that caution is warranted when geofoam is used in areas of high seismicity to anticipate properly the effect of geofoam on the behavior of the embankment and subgrade during strong ground motion shaking.