Performance of a Subgrade-Embankment-Seawall System Reinforced by Drainage PCC Piles and Ordinary Piles Subjected to Lateral Spreading

Coral sand is widely distributed in coastal areas and used as a soil foundation in an increasing number of projects. Historical records show that the liquefaction and lateral spreading of coral sand foundations occurred many times during earthquakes, resulting in serious geological and engineering disasters. Based on a rigid drainage pile, a PCC pile (Large Diameter Pipe Pile by using Cast-in-place Concrete) and drainage body are innovatively combined into a new drainage PCC pile, to reduce the harm caused by liquefaction and lateral spreading of the coral sand foundation. In this study, the seismic response of the subgrade-embankment-seawall system on the coral sand liquefaction site was simulated using a shaking table. The excess pore water pressure ratio, acceleration, average foundation settlement, seawall displacement, embankment deformation, and pile body bending moment of the ordinary pile foundation and new drainage PCC pile foundation under seismic loads of PGA peak ground acceleration=0.05 g, PGA=0.1 g, and PGA=0.2 g on the coral sand site were analyzed and compared. Compared with ordinary pile foundations, the excess pore water pressure ratio, pile bending moment, seawall displacement, foundation settlement, and embankment deformation of the new drainage PCC pile foundation were markedly reduced, while acceleration increased, which showed that the new drainage PCC pile had a positive anti-liquefaction effect on the coral sand foundation.