Numerical Study on Mechanism Responses of Submarine Pipeline Impacted by Bar-Shaped Falling Object

Abstract

Impact caused by bar-shaped falling objects from third-party activities could damage submarine pipelines seriously. In this paper, numerical simulation models of submarine pipelines are established to investigate the damage mechanisms, mechanical behaviors, and energy absorptions of submarine pipelines impacted by bar-shaped objects based on multiple theories and approaches, including elastic-plastic mechanics, geomechanics, elastic foundation beam theory, and finite-element method. The effects of essential physical parameters on the impact behaviors of submarine pipelines are discussed. The results show that the seabed could absorb the highest proportion of impact energy at the final state, but a rock seabed could lead to severe damage to the pipeline. With the increase of the impact velocity, the stress concentration and plastic deformation become serious, as well as the pipeline depression rate and the maximum impact force. High-stress area, plastic deformation area, pipeline depression rate, and absorbed energy proportion increase with the increase of the radius-thickness ratio. The most severe impact damage occurs on the submarine pipelines when a falling object has a tri-prism impact end. The pipeline depression rate increases as the impact angle becomes bigger. An inclined impact could lead to more severe damage if the inclined angle is between 60° and 75°.