Effects of Seabed Shear Strength and Gap between Pipeline and Seabed on Drag Force on Suspended Pipelines Caused by Submarine Debris Flow

摘要

As-laid pipelines in offshore environments might be suspended at a varying distance above the seabed. During the process of run-out of a sliding soil mass/debris, resulting from a submarine landslide, the debris might impact the pipeline. When impacted, the pipeline might interact not only with the debris but also with the seabed sediment, depending upon the gap between pipeline and seabed. Proper quantification of the drag force on the pipeline resulting from submarine landslides is required in the design to avoid pipeline damage and ensure its serviceability. Previous studies show that a number of factors affect the drag force, including the debris strength, diameter of the pipe, velocity of the sliding mass, and depth of embedment when the debris engulfs the pipe. This study presents numerical simulations using a computational fluid dynamics approach that investigates the effects of undrained shear strength of the debris and underlying seabed and the gap between the pipeline and seabed on drag force, in addition to the aforementioned factors.