ABSTRACT
The primary difficulty with wave or seismic loading on seabed sediment is that the induced stresses are transient, each peak lasting from only a fraction of a second to a few seconds. The response of the sediment to this type of loading is different from the response under a sustained load. One possible response for a granular material is that the sediment progressively loses most of its strength or liquefies and flows under its own weight resulting in large permanent deformations. Another alternative is that permanent soil deformations occur only during the short period of time that an induced stress peak exceeds a threshold strength. In this case, movement of the seabed caused by the several peaks of stress during a storm or earthquake may not be serious, provided that large deformations have not occurred and the soil strength after the cyclic loading is still adequate to resist the applied static gravity loads. The response of clays and granular material to cyclic loading are very different and will be treated separately in the following sections.
