Numerical analysis of seabed liquefaction in the vicinity of two tandem pipelines in a trench. (15th December 2022)

• Record Type: Journal Article
• Authors: Chen, Xu; Jeng, Dong-Sheng; Liang, Zuodong
• Is Part Of: Ocean engineering. Volume 266(2022) Part 1
• Publication Date: 2022-12-15
• Subjects: Two tandem pipelines -- Trench -- Wave–current–seabed interactions -- Pipeline spacing -- Pore pressure -- Liquefaction; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2022.112656
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: In engineering practice, pipeline trenching has been adopted as one of effective protection options. Most previous studies mainly focused on the prediction of the seabed response around a single pipeline, although two tandem pipelines have been used in engineering practice for transporting hydrocarbons. This study aimed to investigate the wave–current induced liquefaction around two tandem pipes in a trench. A series of simulations were performed to explore the effect of the horizontal gap ratio of dual pipes in a shared trench on the seabed response, and the results were compared with a single trenched pipe. In the numerical model, we used an integrated two-dimensional model that was developed based on the Finite Volume Method (FVM) in OpenFOAM®. In terms of the flow field, VARANS (Volume-Averaged Reynolds Averaged Navier–Stokes) was applied to simulate the fluid motion, while Biot's consolidation equation was used to govern the seabed model. The numerical examples indicate that twin pipelines semi-buried in close proximity within the same trench significantly impact the flow patterns and seabed response around them. Furthermore, the self-weight of dual pipes, ocean currents and trench configuration have a considerable influence on the evaluation of the liquefaction distribution around two tandem pipelines in a trench. Highlights: A 2D model for Fluid-Seabed Interactions around two tandem pipelines in a trench. It is unreasonable to treat two tandem pipelines with a small gap separately. Seabed response around single and twin pipes in a trench differ significantly. The self-weight of two semi-buried pipes affects the liquefied zone significantly. There is a virtually identical liquefied zone to the pipe–oil system and empty pipes.