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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   (1720 HTML9 PDF(pc) (2176KB)(373)  

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.10 Simplified location of measurement points
Extracts from the Article
采用管线位移反演模型对 3 000 m 悬链线立管在0° 方向2 m/s的背景洋流下位形进行反演重构,以研究测点布置间距对反演结果的影响.图7是OrcaFlex计算得到的结果和本文模型反演得到的结果对比图,黑线是OrcaFlex数值模型计算值,红线是测点间距10 m的反演结果,蓝线是测点间距100 m的反演结果,绿线是测点间距200 m的反演结果.随着测点间距变大,反演的位移场逐渐偏离目标位形,从局部放大图看,测点间距为200 m时,重构位移场严重偏离目标位移场.
为考虑翻转角度对计算结果的影响,在反演之初考虑翻转角度,对测点进行翻转角度修正,采用距离真实翻转角度最近的测点,如图9(b)所示,黑线是在三维海流作用下全局坐标系的X方向,绿线是初始状态下全局坐标系的X方向,在海流作用下,测点1和测点8与黑线的夹角分别是20°和30°,因此采用测点8测得的应变数据作为此位置处的应变值,其他工况和位置以此类推.图10展示4种测点布置方式下的翻转角度转换关系,其中90° 布置的工况不考虑翻转角度效应.
图11是45°、90° 和135° 来流作用下的不同测点布置方式下的位移场重构对比图,黑线是数值模拟计算得到的位移场目标值,粉线是测点90° 布置的重构位移场,蓝线是测点45° 布置的重构位移场,绿线是测点30° 布置的重构位移场,红线是测点全局布置的重构位移场.随着测点布置的加密,重构的位移场逐渐向目标位移场趋近.对于45° 来流的工况,全局布置的重构效果较好,其他布置方式对位移场的重构效果很差;对于90° 来流的工况,45° 布置、30° 布置和全局布置的重构效果明显优于90° 布置的情况,30° 布置和全局布置的重构效果相差不大;对于135° 来流的工况,90° 布置的重构效果明显差于其他布置方式,45° 布置和30° 布置的重构效果相近.不同测点布置方式下重构效果可根据测点的布置位置进行解释,如图10所示,对于45° 来流的工况,黑色实线是数值模拟计算得到的管线翻转角度,三角、方块和五角星分别代表90° 布置、45° 布置和30° 布置下简化的管线翻转角度,3种布置方式下管线的近似翻转角度和真实翻转角度偏差较大,因此反演效果较差;对于90° 来流和135° 来流的工况,除90° 布置的方式外,其他两种布置方式的翻转角度简化值均分布在真实值周围,离散度小,因此位移反演效果明显优于45° 来流的工况.总体来看,随着测点布置越多,位移重构效果越好,测点全局布置基本可准确识别立管的位形形状和位置.
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