Piping erosion of an aged embankment subject to vibration

The piping failure of an aged embankment is frequently reported during the rainy season. Forensic study on the recent collapse of an aged embankment revealed that a cavity formed beneath the conduit in the embankment because of the relative settlement between the ground and pile-supported conduit due to vibration from a nearby pumping station. The cavity shortened the flow length and increased the hydraulic gradient to exceed the critical value, which caused internal erosion. In this study, the failure mechanism of the embankment and effect of vibration were investigated by using a centrifuge model test. The results show that vibration accelerates particle movement, leading to larger settlements and collapse. It also generates excess pore-water pressure, which raises the phreatic surface by up to 10% for specific case considered and consequently increases the hydraulic gradient and the risk of piping. Based on these results, a reinforcement is proposed for aged embankments with cavities that are subjected to vibration.