深海卷管铺设中的管道安全性分析

深海卷管铺设过程中管道发生了复杂的塑性变形，可能造成管道的失效，因此需要对管道的安全性进行评估。为此，首先对卷管铺设整个过程中管道的受力变形情况进行了分析，发现管道在上卷至卷筒时最易发生失效。其次对上卷时管道可能发生的失效形式进行了归纳和分析，获得了管道在各种失效形式下的极限承载公式。然后基于位移控制条件，得到了管道的极限弯曲半径，并结合极限承载公式，建立了管道失效的评价指标。最后以管径为16英寸（406.4 mm）的管道为实例，对管道的安全性进行评估，并采用有限元软件对管道上卷时张力对管道椭圆度的影响进行了分析。结果表明：①较大径厚比的管道在上卷时更易于满足极限载荷承载条件，但是对管道截面变形不利，当径厚比达到20时，不满足位移控制条件，已不适用于卷管法铺设；②较高的管材等级对卷管铺设中管道安全性有利；③上卷张力对管道椭圆度的影响较小，可以忽略。

Analysis on pipe safety during reel lay in deep sea

Pipe failure may be resulted from complicated plastic deformation during reel lay in the deep sea, so it is necessary to evaluate the safety of pipelines. First, analysis was conducted on the force deformation of pipes in the whole process of pipe laying. It is indicated that pipe failure tends to occur while the pipe is being reeled on the reel. Second, calculation formula of ultimate bearing capacity was established for various pipe failures by analyzing and summarizing each possible pipe failure form during reeling. Third, ultimate bending radius of pipelines was obtained based on the displacement control conditions. And evaluation index of pipeline failure was prepared by combining with ultimate bearing-capacity formula. And finally, pipe safety was evaluated based on a case study of a pipe with a diameter of 16 inches (406.4 mm). And then, the effect of tension on pipe ellipticity during reeling was analyzed by using the finite element software. It is shown that higher diameter-thickness ratio is adverse to pipe section deformation, although ultimate bearing conditions tend to be satisfied during coil loading. And when the diameter-thickness ratio is 20, displacement controlled conditions can not be satisfied and the reel lay method is not applicable. Besides, higher pipe grade is favorable for pipe safety in the process of reel lay. And finally, the effect of reeling tension on the ellipticity of pipes is negligible.