寒区输油管道基于应变设计的极限状态研究

The limit state of pipeline based on strain design in cold regions

寒区输油管线沿线地质环境复杂,滑坡、冻胀、融沉等自然灾害会导致管道形成大差异变形量.而差异变形量所引起的应力应变行为直接影响管道的安全服役性能,严重时会使管道破坏失效.基于寒区输油管道在实际服役工况下的受力变形条件,充分考虑冻胀效应、油压效应和热应力效应对输油管道的影响,分析了不同长度、壁厚、油压条件下轴向拉伸应变的分布规律及其影响因素.基于轴向应变设计理论准则,建立了上述条件下输油管道的极限服役状态,得到了对应状态下输油管道的许应最大极限冻胀变形量.结果分析表明,采用基于应力的设计准则偏保守,采用基于轴向应变的设计准则能更多的利用管材的变形性能.可为管道的合理设计、安全评价、完整性管理提供一定的理论参考.

Complex geological environment along the pipeline in cold regions,such as landslides,the frost heave and thawing settlement,probably makes the pipe a large differential deformation leading to its failure. Large differential deformation caused by the stress and strain behavior directly affects the safety of pipeline during operation,and even damages the pipe. Based on the actual stress / strain conditions of oil pipeline in cold regions,we fully considered the frost heave,oil pressure and thermal stress effects on the pipeline,and analyzed its factors and the axial tensile strain distribution with different lengths,thicknesses,oil pressures. According to axial strain design criterion,the limit conditions of the oil pipelines were established. The maximum limit of the frost heave deformation for pipelines was obtained. Results showthat the stress-based design criteria is conservative,and the strain-based design can use the deformation of the pipes more efficiently. This article can provide references for the reasonable design,safety evaluation and integrity management of pipeline.