防止温度应力下海底管线发生整体屈曲的工程措施研究

Engineering Measures for Preventing Upheaval Buckling of Buried Submarine Pipelines

为减小油气输送难度和避免原油固化,石油、天然气通常在高温高压下输送.输送过程中的高温和高压导致海底管线中产生较大的附加应力,附加应力的不断累积造成管线发生整体屈曲.对于埋地的海底管线通常会产生竖向屈曲大变形而影响使用甚至破坏.因此,需对有可能产生整体屈曲的管线采取工程防护措施.结合我国海洋工程中管线常用的铺设及保护措施,对处于保护状态下管线由温度应力引起的整体屈曲特性进行理论分析和数值推导,对沟槽保护、沟槽掩埋保护以及压块保护措施的有效性进行了系统分析和对比.

In-service hydrocarbons must be transported at high temperature and pressure to ease the flow and prevented solidification of the wax fraction.High temperature and pressure induced addition stress in the pipeline,and its accumulation will cause upheaval buckling of the pipeline.If such expansion is resisted,for example by frictional affects of the foundation soil over a kilometer or so of pipeline,compressive axial stress will be set up in the pipe-wall.When the value exceeds the constraint of foundation soil on the pipeline,sudden deformation will occur to release internal stress,which is similar to the sudden deformation of strut due to stability problems.The upheaval buckling may jeopardize the structural integrity of the pipeline.Therefore,the effective engineering measure against this phenomenon plays an important role in submarine pipeline design.In terms of the pipeline installation and protection measures commonly used in Bohai Gulf,three engineering measures was investigated in great details.The analytical method was introduced and developed to consider the protection effect of anti-upheaval buckling of the pipeline.The analyzing results showed that the amplitude of initial imperfection had a great effect on the pipeline thermal upheaval buckling.Both trenching and burial and discrete dumping were effective on preventing the pipeline from buckling.The initial imperfection and operation conditions of the pipelines determined the covered depth and the number of layers of protection measures.