Seabed responce to water waves

The final objective was to evaluate the stability of an offshore pipeline from a geotechnical point of view. On the Dutch part of the Continental Shelf pipelines are used for the transportation of oil and gas and utilities liRe glycol. The mean waterdepth on this part of the North Sea varies from 20-40 meters. As this region is a major fishing area while in some places the pipelines cross the shipping lanes the authorities demand that pipelines are buried to a depth of 1.00 m below the surface of the seabed. In view of the high costs of the burying operation and because of some reported cases of instability an evaluation of the possibility of instability seems relevant. In some cases regulations were released to lay pipelines unprotected on top of the seabed. In these cases it was supposed that the pipeline would be buried by natural processes. After installation the behaviour of these pipelines was monitored. Although this method was not successful in all cases it could be concluded that self-burial of a pipeline is possible. The morphological aspects of potential self-burial together with a study into the forces induced by the dynamic fluid pressures have been studied in separate projects.