Anchoring in shallow waters is one of the main causes of submarine pipeline damage. In this paper, a finite element model based on the Coupled Eulerian Lagrangian (CEL) method provided in ABAQUS/Explicit is proposed. The model involves the interaction between the anchor, soil and pipeline. To save computational cost, the pipe section close to the impact point is modelled with the shell elements, while the other section is modelled with beam elements. Here nonlinear spring elements are used to simulate the pipe-soil interaction. Effects of the burial depth of pipeline, the impact velocity of anchor and the undrained shear strength of clay on the pipeline damage are analyzed. The present work is supposed to lay the foundations for future design of pipeline burial and the evaluation of pipeline damage due to anchor impact.
With the development of world economy, the international community's demand for the exploitation of offshore oil and gas resources is increasing. The submarine pipeline has been widely used in the transportation of oil and natural gas resources due to its advantages of high transportation efficiency, large capacity and not being affected by weather. Submarine pipelines are often called the "lifeline" of the oil industry, which emphasizes their importance for the transportation of offshore oil and gas (Jiang et al.,2019). With the development of marine energy exploration, people pay more attention to the safety and stability of submarine pipelines. With the increase of third-party activities offshore, submarine pipelines may be damaged by the impact from falling objects during platform operation, anchoring and fishing. According to statistics, third-party damage is the main cause of pipeline failure in Chinese waters, and anchoring impact load is the main type of third-party damage, as shown in Fig. 1 (Gao et al., 2018). This may lead to the pipeline deformation or buckling, and may even lead to pipeline rupture and oil leakage, polluting the ocean environment (Zeinoddini et al., 2013). In most cases, risk analysis should be made to evaluate the probability of third-party damage like anchoring and fishing. If the likelihood is efficiently small, protection of the pipeline is not necessary. If it is not small, reasonable protection of the pipeline is necessary and important. In this case, burial of the pipeline is the most common method to protect it from impacting damage.
