Wave-induced seabed liquefaction and the stability of marine pipelines

摘要

Pipelines on the seabed are customarily designed on the assumption that the seabed itself is stable. Field experience, laboratory experiments and theory all show that this assumption is almost invariably incorrect, and that the seabed becomes unstable long before the design conditions for the pipeline are reached. A program within the EU LIMAS (Liquefaction around MArine Structures) project carried out experiments in a wave flume on a pipeline resting on a fine-grained noncohesive seabed material. They demonstrate the coupling between the initiation of movement in the bed and the instability of the pipeline, and the profound influence of the mean relative density of the pipeline. The experiments are linked to the development of a new theoretical model of liquefaction. The results suggest a new approach to the design of stable marine pipelines.