Seismic performance of earth dams founded on liquefiable soil layer subjected to near-fault pulse-like ground motions

Abstract

Liquefaction-induced flow slide is one of the main reasons to cause severe damage of embankment dams. In this paper, the effect of near-fault pulse-like ground motions on the seismic performance of earth dams susceptible to liquefaction-induced damage is quantitatively investigated. A generic earth dam founded on a liquefiable soil layer is modeled in OpenSees based on a finite-element approach. Two suites of near-fault ground motions, namely one pulse-like and one ordinary suite, respectively, are selected from the NGA-West2 database. Both selected ground-motion suites have statistically comparable earthquake magnitudes, rupture distances, and shaking intensities. Dynamic analyses are then conducted for the earth dam subjected to both ground-motion suites. Comparative results indicate that the pulse-containing ground motions have a greater potential to trigger liquefaction in the loose-sand layer as compared to the ordinary near-fault motions. As to post-liquefaction performance, using the pulse-containing ground-motion suite leads to an enlarged distribution of both maximum lateral displacements and crest settlements of the earth dam, in comparison with those caused by the ordinary ones. Therefore, when subjected to pulse-like ground motions, an earth dam at sites susceptible to liquefaction hazard would possibly suffer an exacerbated post-liquefaction deformation and damage. Besides, it is found that the resultant lateral displacements and crest settlements for the pulse-like suite are strongly correlated to the duration and cumulative-energy parameters of ground motions.