Wave loading
Wave loading is the phenomenon by which the passage of a wave over sediments causes liquefaction, or the temporary conversion of the sediment into a suspension.
The mechanism of wave loading
When a wave passes over a sediment, the weight of the water forces some water below the sand. As the wave recedes, the pressure on the water beneath the sand decreases, allowing the water to push back up to the surface. As the water pushes up, in converts the sand into a suspension, a process known as liquefaction.
Examples of wave loading
- Walking on the beach: As one walks through the waves on the beach, as the wave recedes, one feels the sand becomes soft and mushy beneath one's feet, and one sinks in.
- Formation of beaches: As each wave trough approaches, sand on the beach is lifted from the sea floor slightly, nudging the sand slightly upslope toward the beach. This is the reason beaches are sandy.
- Offshore Storms and pipes: As large waves pass over buried pipes, water pressure increases above it. As the trough approaches, pressure over the pipe drops, and stores, high-pressure water in the sediments flows upward. In major storms, this can break pipes.
- Engineering Oil Platforms: The effects of wave-loading are a serious issue for engineers designing Oil Platforms, which must contend with the effects of wave loading, and have devised a number of algorithms to do so.
- Earthquakes: An earthquake on 18 November 1929 on the the continental slope off the coast of Newfoundland caused a 60-mile per hour current of muddy water, causing wave loading. Twelve transatlantic phone cables were snapped in a total of 28 places, sequentially, as the wave passed.