Developing characteristics of standing wave-induced residual excess pore water pressure in the seabed

The interaction among wave, seabed and marine structure is an important issue in geotechnical engineering as well as coastal engineering. It is important for civil engineers who have to design the foundation for various marine structures and verify the instability of the seabed to understand variations of pressures and stresses in the seabed induced by waves. Previous studies showed that there are two different mechanisms in the seabed instability, particularly, in the case of wave-induced liquefaction. The first is caused by the transient or oscillatory nature of excess pore water pressure, and is accompanied by damping of the amplitude and lagging of the phase in the variation of pore water pressure. The second is caused by the residual or progressive nature of excess pore water pressure, which appears after a certain number of cyclic waves loading. This study numerically analyzed the generation of excess pore pressure in the seabed induced by a standing wave. Particularly it investigated the developing characteristics of residual excess pore pressure in the excess pore pressure generated in the seabed below the antinode and the node of a standing wave. In addition, the numerical results are compared to experimental ones. They exhibited good agreement qualitatively in the developing characteristics of the residual excess pore pressure.