波浪式拖管法铺设海底管道力学性能研究

海底管道铺设是海洋油气资源开发的重要环节，传统的拖管法不能很好地适应海洋深度和复杂环境的变化。针对 Acergy公司在Girassol项目中提出的一种波浪式拖管方法，对其应用于2.0 km 长海底管道铺设进行分析。首先，结合深水海洋环境特征，采用集中质量法建立管道拖航数值模型，并介绍管道、拖缆和浮筒力学计算及水动力荷载计算方法；其次，基于非线性有限元OrcaFlex软件对拖管过程建模，以模拟实际项目拖管过程；然后，通过对比相同条件下的单波式和双波式两种拖管方式，探讨管道和拖缆的动态力学性能变化；最后，针对不同浮重比、拖航速度、拖缆长度和悬垂角、海流流速和流向角等因素展开敏感性分析。结果表明：波浪式拖管法可以有效地降低施工时对拖缆的张力需求，但也会因此增加管道局部弯矩和应力响应；相对于单波式拖管，双波式拖管在缓解由于拖航速度等变化而产生的管道局部损伤效应上更有优势，并能较好地适应不同水深环境；复杂的海流工况对拖航时管道的力学性能影响十分显著，施工前应选择合适的铺设窗口期以防止管道产生损伤。

Mechanical performance study of submarine pipeline laid by wave towing method

The laying of submarine pipelines is a crucial aspect of marine oil and gas resource development. Traditional towed methods struggle to adapt to the variability of ocean depths and complex environments. In response to Acergy’s proposal for a wave towing method in the Girassol project, this study analyzes its application in the laying of a 2. 0 km-long seabed pipeline. Firstly, considering the characteristics of deep-sea marine environments, a numerical model for pipeline towing is established using the concentrated mass method. Mechanical calculations for the pipeline, tow cable, and floatation devices, as well as hydrodynamic load calculations, are introduced. Secondly, a modeling of the towing process using the nonlinear finite element software OrcaFlex is conducted to simulate the actual project’s towing process. Next, the dynamic mechanical performance variations of the pipeline and tow cable are explored by comparing two towing methods: single-wave and double-wave towing under similar conditions. Finally, sensitivity analysis is performed on factors such as buoyancy-to-weight ratio, towing speed, tow cable length and sag angle, as well as current velocity and direction. The results indicate that the wave towing method effectively reduces the tension demand on the tow cable during construction but may increase local bending and stress response of the pipeline. Compared to single-wave towing, double wave towing shows advantages in mitigating local damage effects caused by variations in towing speed and is better suited to different water depths. The influence of complex ocean current conditions on the mechanical performance of the pipeline during towing is significant, emphasizing the importance of selecting appropriate laying windows before construction to prevent pipeline damage.