含初始缺陷海底管道非线性屈曲失稳外压判别方法研究

Identification of External Pressure of Nonlinear Buckling Instability of Subsea Pipeline with Initial Imperfections

海底管道处于深海高压环境,任何微小的缺陷都可能大幅降低管道的屈曲压力。将线性屈曲分析的屈曲模态作为初始缺陷的参考值,对受外压海底管道进行非线性有限元分析。研究结果表明,受外压作用的海底管道在径向产生膨胀变形和压缩变形,而且变形沿轴向传播。基于径向压缩变形与膨胀变形的比值随外压的变化曲线规律,提出了判定海底管道非线性屈曲的临界外压的拐点方法,该方法能够准确判定临界外压值。应用拐点方法,分析了不同缺陷和径厚比下海底管道的临界外压。

The subsea pipeline is in a deep-sea high-pressure environment,and any minor defect could significantly reduce the buckling pressure of the pipeline.Taking the buckling modes of linear buckling analysis as the reference value of initial defects,the nonlinear finite element analysis of submarine pipelines under external pressure was carried out.The results show that the submarine pipeline subjected to external pressure produces radial expansion deformation and compression deformation,and the deformation propagates along the axial direction.Based on the curve of the ratio of radial compression and expansion deformation with external pressure,a method of inflection point for determining the critical external pressure of nonlinear buckling was proposed,which can accurately determine the critical external pressure.The inflection point method was used to analyze the critical external pressure of subsea pipelines of different defects and diameter thickness ratios.