This study examines the behavior of submarine gravity flows of liquefied sand and their impact on subsea structures through centrifuge model tests. The centrifuge model testing technique provides an effective method for simulating submarine gravity flows, reproducing prototype-scale conditions under enhanced gravities. A sediment gravity flow with a velocity of 2.5 m/s, generated by the liquefaction of a 5 m-thick sand bed on the prototype scale was successfully reproduced in the drum centrifuge channel under a centrifuge acceleration of 50g. The impact pressures of the sediment gravity flow on the structures placed on the channel floor were measured. It was found that when the sediment gravity flow head reached the structure, the pressure on the structure rapidly increased, and then remained at a high level followed by a gradual decrease in the impact pressures. The pressure exerted on the structures was found to be approximately twice that of the pressure acting on the channel floor. This suggests that embedding structures in the seabed can substantially reduce impact pressures compared to those when placing them on the seabed surface.

Centrifuge model test,gravity flow,liquefaction,impacts,subsea structure