单层和双层足尺度海底管道抗冲击性能分析

海底管道在服役过程中除了受到常规荷载作用外,还会受到各种意外的冲击载荷作用而失效。为了研究承受横向冲击载荷作用下海底管道的动态特性,对三个单层和一个双层的足尺度管道进行了落锤冲击试验,获得了横向冲击作用下管道的破坏形态、冲击力时程曲线、位移时程曲线及应变时程曲线。建立了分析冲击荷载作用下海底管道失效过程的有限元模型,并通过与试验结果的对比验证了模型的精确性。利用有限元模型研究了冲击高度、材料屈服强度、管道长细比和径厚比等参数对管道抗冲击性能的影响。研究结果表明:海底管道在冲击载荷作用下的破坏模式是局部凹陷处弯曲屈服,由管道的整体弯曲变形与冲击凹痕部位的局部弯曲耦合形成。与单层管道相比,双层管道由于内层管道参与抵抗冲击荷载的作用,从而具有更好的抗冲击性能。管道钢材的屈服强度的增加可有效减小冲击作用下的局部凹陷变形。

Anti-impact performance analysis of single-layer and double-layer full scale submarine pipelines

Besides conventional loads,submarine pipelines may be damaged by various unexpected impact loads.Here,to study dynamic characteristics of submarine pipelines under lateral impact load,drop hammer impact tests were conducted for 3 single-layer and one double-layer full-scale pipelines.Failure mode,impact force time history curve,displacement time history one and strain time history one of pipelines under transverse impact were obtained.A finite element model was established to analyze failure process of submarine pipeline under impact load,and the accuracy of the model was verified through comparing with test results.Effects of impact height,material yield strength,slenderness ratio and diameter to thickness ratio of pipeline on anti-impact performance of pipelineswere studied using the finite element model.Results indicated that the failure mode of submarine pipelines under impact load is bending yield at local dent,it is formed by coupling of whole bending deformation of pipeline and local bending of impact dent;compared with the single-layer pipeline,the double-layer pipeline has better anti-impact performance due toits inner layer pipe participating in anti-impact load;increasing yield strength of pipeline steel material can effectively reduce local sag deformation under impact load.