Numerical Simulationof Mechanism Of Local Scouring And Force On The Submarine Pipeline

The local scour below offshore pipelines is induced by the long-termed erosion ofcurrents and waves. The free span propagates along the pipeline and induces structural andfatigue failure of pipelines. A tremendous economic loss and environmental disaster willoccur, once the pipeline fails. So, it is important to forecast the scour deep below pipeline.At first, this paper discusses the action of flow field around submarine pipeline under theoblique flow, analysis the influence of flow field under different angle of ocean current andgap ratio, so as to further discuss the current flushing action of subsea pipeline. After theanalysis of the flow field, this article establish the local scour movable bed model ofsubmarine pipeline in2D situation, discuss the changes of the seabed during local scour andthe factors that influence the maximum equilibrium scour depth, and get the relationshipbetween diameter of pipelinesand the maximum equilibrium scour depth and the relationshipbetween current velocity and the maximum equilibrium scour depth. Finally, according to thetheory of elastic foundation and saint venant’s principle, considering the coupling effect of theseabed and the pipe, establish finite element models of submarine pipeline based on ansys,analysis the stress of pipeline in different span and the current, and provide a theoretical basisof the prevention and treatment the span of pipelines.