| 摘要: |
| 海底底床在复杂多变的海底环境影响下可能发生冲刷使海底管道悬跨。目前, 对海底管道冲刷的研究和认识多基于平坦底床, 对处于复杂海底底床尤其是活动底床的海底管道局部冲刷规律和动力机制的认识不足。通过室内水槽实验并结合数值模拟, 分析单向流作用下活动沙丘对过境管道底床局部冲刷特征的影响, 并提出了其动力机制。结果表明, 当过境管道位于沙丘迎流侧时, 管道下游侧的冲刷更快且更严重, 此时管道附近将经历管道前端涡流冲刷、后端尾涡冲刷和底部孔道冲刷3个动力过程。当管道位于沙丘背流侧时, 管道上游侧的冲刷更加严重; 沙丘背流侧水流分离, 流速分离区内近底床的水流方向发生反转, 使管道局部冲刷最先发生在管道迎流侧; 管道初始埋深越小, 冲刷坑尺寸越大; 管道延伸角度越大, 冲刷坑尺寸越大。研究结果为合理评估活动和复杂底床对海底工程设施的影响提供了科学参考。 |
| 关键词: 移动沙丘 过境海底管道 局部冲刷 单向流 |
| DOI：10.11759/hykx20241125001 |
| 分类号:P736 |
| 基金项目:国家自然科学基金(42276057, 41876035); 中国地质调查局舟山海洋地质灾害野外科学观测研究站开放基金(ZSORS-22-06) |
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| Study on the effect of active sand dune on seabed scouring near transit pipeline under unidirectional flow |
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GAO Min1,2, MA Xiaochuan2,3, HE Yiwei2,3, GONG Teng1,2
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1.College of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao 266590, China;2.Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;3.University of Chinese Academy of Sciences, Beijing 100049, China
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| Abstract: |
| Under the influence of a complex and variable seabed environment, the scouring of the seabed may occur, causing submarine pipelines to become exposed. At present, the research and understanding of submarine pipeline scour are mostly based on a flat bottom bed, and there is insufficient understanding of the local scouring behavior and dynamic mechanisms of submarine pipelines in complex seabed conditions, especially an active bottom bed. Through indoor flume experiments and numerical simulations, the influence of active dunes under unidirectional flow on the local scouring characteristics of transit pipelines’ bottom beds is analyzed, and its dynamic mechanism is proposed. The results show that when the transit pipeline is located on the headwater side of the dune, scouring on the downstream side of the pipeline is faster and more serious, and then three dynamical processes will be experienced in the vicinity of the pipeline: eddy scouring at the front end of the pipeline, trailing eddy scouring at the back end of the pipeline, and scouring at the bottom orifice. When a pipeline is located on the backflow side of the dune, scouring on the upstream side of the pipeline is more serious; flow separation on the backflow side of the dune and the reversal in the flow direction near the bottom bed within the flow separation zone make the local scouring of the pipeline to occur first on its headwater side. In addition, the smaller the initial burial depth of the pipeline, the bigger will be the size of the scouring pit; the bigger the angle of the extension of the pipeline is, the bigger is the size of the scouring pit. The results of this study provide a scientific reference for the rational assessments of the impact of active and complex bottom beds on submarine engineering facilities. |
| Key words: moving dune transit submarine pipeline localized scour unidirectional flow |
