Centrifuge Modeling of Rock-Fill Embankments on Deep Loose Saturated Sand Deposits Subjected to Earthquakes

Rockfill is commonly used for construction of artificial islands, breakwaters, jetties, quay walls, coastal defenses, protective barriers for reclaimed land, and even as ship impact protection structures around bridge piers. The economic construction method often involves rock dumping onto loose or liquefiable sediments with little or no ground improvement. Hence in a seismic environment, these rock-fill or rubble mound structures are potentially vulnerable to failure due to pore pressure generation effects of the underlying deposits. This paper presents experimental investigation carried out using dynamic centrifuge modeling to study the seismic performance of rock-fill or rubble mound embankment structures on liquefiable sand deposits. The centrifuge test results indicate that the rock-fill embankments suffer substantial settlement owing to rock-fill penetration into the founding sand deposit assisted by the pore pressure generation effects. This mechanism of failure was not, however, observed for a sand embankment where the particle size distribution is comparable to the foundation. This result has important implications in the design methodologies adopted for rock-fill or rubble mound structures.