Experimental Investigation on Seabed Response Under Wave-Induced Motion of Marine Structure

Abstract

Periodic wave loads acting on marine structures cause them to vibrate accordingly. The wave-induced vibration of marine structures can induce seabed liquefaction, and result in foundation instability. Therefore, seabed stability induced by wave-induced vibrations of marine structures should be one of the key issues to guide the design of marine structures to ensure their safety. In this study, the effect of wave-induced vibration of marine structure on seabed liquefaction was carefully investigated based on a flume experiment. The effects of grain size of sandy seabed sediments, self-weight of structures, and amplitude and period of external forces acting on the structures on the spatial distribution of super-hydrostatic pore water pressure in the seabed, and influences of them on the liquefaction characteristics of the seabed were also investigated through modeling experiments. The experimental results show the accumulation of super-static pore water pressure caused by wave-induced vibration of the structure is more obvious in the experiments with smaller grain size sediment; the peak value of the transient pore water pressure in the seabed increases with the increase of the self-weight of the structure, while the peak value of the residual pore pressure shows a tendency to increase firstly and then decrease with the increase of the structure's self-weight; the amplitude of the external force acting on the structure increases and the period decreases, which will lead to the accumulation of superstatic pore water pressure and liquefaction of the seabed. An increase in amplitude or decrease in the period of external force on the structure will cause the accumulation of superstatic pore water pressure and the deepening of liquefaction.