Analysis of the Influence of Submarine Pipelines Under the Action of Multiple Factors by Anchor Dragging

Abstract In recent years, there have been many submarine pipeline damage accidents, a large part of which is caused by the anchoring operation of ships. In order to study the damage of submarine pipeline under the tug of ship anchor, a tug load analysis model was established by finite element method, and the tug load was applied to the center of the pipeline to simulate the tug of ship anchor. The influence of sensitive factors such as the Angle between the drag force and the plane of the pipeline, the properties of soil, the flow rate of seawater and the ratio of diameter to thickness of the pipeline on the stress and displacement of the pipeline is mainly discussed. The results show that the increase of the Angle between the dragging load and the pipeline level will reduce the maximum Mises stress during dragging, but increase the maximum displacement of the pipeline. The stiffer the soil is, the stronger the protective effect is on the pipeline. In the silty clay environment, the deformation and bending stress are the largest when the pipeline is dragged by the anchor chain. With the increase of seawater velocity, the maximum drag force of the anchor decreases, resulting in the bending stress and displacement of the pipeline also decrease. The increase of pipe diameter to thickness ratio will reduce the ultimate bearing capacity of pipe. Reducing pipe diameter to thickness ratio appropriately is an effective way to improve the resistance to pipe instability in the bent pipe combination section. In the process of design, construction, operation and maintenance of submarine pipelines, it is necessary to ensure that the buried depth of pipelines is sufficient, reduce the risk of pipeline being dragged by the anchor chain, and improve the essential safety of submarine pipelines in service.