海洋非粘结柔性管道扭转失效特征行为分析研究

Study on Failure Behavior of Flexible Pipes in Torsion

分析了扭转荷载引起的三种海洋非粘结柔性管道截面可能的失效模式:铠装钢丝强度失效、内层压溃失效及铠装钢丝屈曲失效。通过管道扭转时铠装钢丝的应力及层间相互作用的分析,对每种失效模式给出了失效判据表达式。通过综合对比分析,提出了非粘结管道截面最大允许扭转角度的保守预测方法。以某典型经济性柔性管道为例进行抗扭转能力的分析。计算结果显示,在反扭情况下骨架层压溃失效是最易发生的一种失效行为,其对应的扭转角度可用于该管道允许最大扭转角度的设计预测值。这项研究可以为海洋工程类似管缆结构抗扭转能力的设计提供参考。

In order to effectively investigate the maximal allowable torsional angle of an un-bonded flexible pipe in torsion, three potential failure modes are studied: tensile armor strength failure, inner layer collapse failure and tensile armor buckling failure. Stress of tensile armor as well as interactions between layers due to torsion is analyzed theoretically to obtain criterion expressions for various failure modes. A conservative prediction of maximal allowable torsional angle of the flexible pipe is proposed. The order in which failure modes occur may vary with structural parameters such as the spiral angle and radius of the armor wires. Finally, the results of a case study show that inner layer collapse failure is prone to occur, and corresponding torsional angle can be used as the maximal allowable torsional angle. The research may provide a good reference to estimation of the torsional capacity of flexible pipes.