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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   (1627 HTML9 PDF(pc) (2176KB)(308)  

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.11 Comparison of displacement field reconstruction under different measurement point arrangements
Extracts from the Article
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.
为更直观地展示测点布置对位移场重构的影响规律,图12展示3种来流下重构位移场的平均相对误差.对于90° 布置方式,反演误差最大,个别工况的反演误差甚至超过100%.随着测点位置布置的更加精确,重构位移场的误差越来越小.对于30° 布置方式,除45° 来流下Y方向的预报平均相对误差较大,其他工况和位置的平均相对误差均在12%以内.对于全局布置方式,45° 来流下Y方向的预报平均相对误差降至13.5%,其他工况和位置的平均相对误差均在10%以内.部分工况全局布置下的X方向和Z方向平均相对误差大于30° 布置的工况,但从图11中可以看出全局布置的重构位形更接近目标位形,平均相对误差更大的原因是全局布置对XZ方向位移较小的区域重构效果较差,更小的基数导致更大的相对误差.
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