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Inversion of Displacement Field of Marine Slender Pipelines Under Three-Dimensional Background Ocean Currents
GUO Li, YUAN Yuchao, TANG Wenyong
Journal of Shanghai Jiao Tong University    2025, 59 (12): 1815-1823.   DOI: 10.16183/j.cnki.jsjtu.2024.007
Abstract   (275 HTML8 PDF(pc) (2176KB)(284)  

Marine pipelines are widely used in offshore engineering and are highly vulnerable to accidental damage caused by underwater structures such as ship anchors and deep-sea submersibles, especially in the dark and unpredictable marine environment. Research on configuration monitoring of marine pipelines is essential to ensure their operational safety. This paper develops a displacement field inversion model for marine pipelines under the influence of three-dimensional background ocean currents, based on the inverse finite element method. The model consists of an input parameter module, a coordinate conversion module, and a displacement reconstruction function module. It takes into account key characteristics such as large curvature, three-dimensional coupling with large displacements, and local flipping behavior. The proposed approach addresses the technical challenges associated with low-order deformation modes and irregular displacement patterns. The impact of the number and layout of monitoring points on the accuracy of displacement field inversion is studied. The results show that the layout with a monitoring point spacing of 100 m and an angle of 30° can meet the engineering accuracy requirements. The findings of this paper can provide valuable insights and methods for the design of marine pipeline health monitoring systems.


Fig.3 Measurement points
Extracts from the Article
采用悬链线管线位移场反演模型对3 000 m长的悬链线立管在vf=2 m/s的背景洋流下位形进行反演重构,验证本文提出的模型准确性,立管参数参考文献[13],如表1所示.采用OrcaFlex求得悬链线立管的位形和应变分布,其中应变是管线位移场反演模型的输入参数,位移是管线位移场反演模型的验证参数.测点的布置位置如图3所示,以悬链线立管在无海流作用状态的初始形状为基础,在触地点建立坐标系,原点设置在触地点,XO1Z 平面与触地点和悬挂点在同一平面内, Z方向垂直向上,Y方向垂直于XO1Z平面,分别在管线横截面的0°、90°、180° 和270° 共4个位置布置测点,测点1和测点2用于测量XO1Z平面的应变,测点3和测点4用于测量YO1Z平面的应变,对于二维悬链线海洋管线位移场反演研究,仅用到XO1Z平面数据及相关自由度.
钢制悬链线立管在三维背景洋流作用下会发生翻转,导致初始位形下的顺流向和横流向测点偏离初始位置,忽略翻转效应对管线的影响将带来巨大的预报误差.图6展示45° 背景洋流下悬链线立管翻转角度分布,从悬挂点开始到触地点,立管的翻转角度从40° 逐渐增加至70°,图中距离顶端800 m处的位置,缆线的翻转角度达到了60°,倘若仍然采用图3中的测点进行反演计算,由于缆线横截面上的各点的应变并不是线性分布的,得到的局部位移和转角很难映射到全局坐标系下,这导致在位移反演过程中产生数值误差,所以立管位移反演要着重考虑翻转效应的影响,对翻转后的应变数据进行精确识别是关键.
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