Seismic response characteristics and liquefaction risk of artificial island with saturated hydraulic fill coral sand

Marine artificial islands are generally constructed by hydraulic fill coral sand. Existing seismic damages show that the saturated coral sand foundation faces serious liquefaction risk. However, previous studies on the liquefaction of artificial islands mainly concentrate on the damage resulting from seabed site liquefaction, neglecting the liquefaction risk of island backfill material. This study focuses on the seismic response characteristics and liquefaction risk of islands. Firstly, a series model of seismic wave analysis and liquefaction analysis is innovatively proposed, the proposed analysis method can effectively analyze the liquefaction risk characteristics caused by offshore ground motions that include real site features of the seabed and artificial island. Subsequently, the influencing factors of seismic response and liquefaction risk are discussed, such as the relative density and thickness of the coral sand foundation, seawater and seabed site conditions. The results indicate that the liquefaction area is significantly decreased when the relative density increased from 55% to 65%. Notably, when the relative density is greater than 75%, the continuous increase of the relative density has limited improvement in the anti-liquefaction ability. The influence of seawater and nonlinear silt layer on the seabed is limited.