考虑土体阻力增长的管线轴向步进理论解

Analytical solution for predicting pipeline walking considering axial soil resistance increment

摘要:

深海管线是海洋石油开采系统中重要的石油输送结构.为保证石油的流动性,在输送石油时需要对管线进行加热.管线在温度荷载循环加载的过程中会产生管线的轴向步进,使得管线出现整体性位移,严重威胁管线系统的安全.管线的一个荷载循环周期会持续很长时间,在此期间管线周围土体强度上升,管线在整个循环周期内受到的土体阻力并非定值.本文通过理论研究,分析土阻力变化前后的管线轴力分布曲线,推导了考虑单次荷载循环中土体阻力变化后轴向步进的理论解,并采用所推导的解析解对工程算例数据进行分析和计算.

Abstract:

Deep-water pipeline system is an important structure that transports oil and gas in offshore engineering. To ensure the fluidity of oil, pipelines are usually applied with high temperature during operation. The asymmetric expansion and shrink can make the pipeline move axially and globally toward one direction. The phenomenon is called pipeline walking, which is a severe challenge for the safety of pipeline systems. The working period of pipeline lasts for a long time, starting from heating up and ending in cooling down. Therefore, the soil resistance on pipeline in the cooling down process may be larger than that in the heating process due to soil consolidation, and the soil resistance of the overall working period is not a constant value. Through theoretical analysis, the effective axial force along the pipeline considering soil resistance increment within one loading cycle was investigated, and a walking-rate prediction method was proposed. In addition, an engineering case was analyzed based on the obtained analytical solution.