Abstract Submarine high-temperature and/or high-pressure (HT/HP) pipelines used to transport oil and gas in different areas of the world are susceptible to global buckling. If the pipelines are simply laid on the seabed, buckling will likely occur in the horizontal plane, while if buried in a trench, buckling will probably arise in the vertical direction. The latter buckling mode may lead to catastrophic pipeline failure potentially associated with massive oil leakage and severe environmental damage. Concerns about upheaval buckling have motivated a number of researchers to investigate the uplift resistance of buried pipelines. The objective of the work presented in this paper is to evaluate the effects of various parameters on the resistance to upheaval buckling of buried submarine pipelines. A numerical approach was adopted to build representative and reliable 3D models of 100 m long embedded pipelines, using the specialized finite element software ABAQUS. Starting with a baseline model of a pipe buried in a medium dense sand with fines, the effects of pertinent parameters on the uplift resistance were explored for two scenarios: (1) uplift of the full pipeline length, which in essence captures the plane strain 2D response and (2) uplift of a central middle length of 20 m. Specifically, the effects of the apparent cohesion of the soil due to the presence of fines, pipeline diameter, embedment depth and diameter to wall thickness ratio were investigated. The uplift forces obtained were normalized in reference to actual pullout and/or effective pipe lengths. The results indicated that the normalized uplift forces obtained in the 3D analyses at high pipeline displacements were in close agreement with those yielded by plane strain models. The model analyses indicated that the contribution of soil apparent cohesion to the uplift resistance was significant. The work indicated that as the level of confinement increases (due to an increase in embedment depth and/or pipeline diameter) the uplift resistance increased, whereas the relative contribution of soil cohesion to the resistance decreases. The paper includes a comparison of the FE results obtained in this study with the available predictive/analytical methods, along with a discussion of which best captured the failure mode and resistance to uplift values of the numerical model.

中文翻译：

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埋地海底管道抗剧变屈曲土壤抗力数值有限元建模

摘要 世界不同地区用于输送石油和天然气的海底高温和/或高压（HT/HP）管道容易受到全球屈曲的影响。如果管道只是简单地铺设在海床上，则在水平面上很可能会发生屈曲，而如果埋在沟渠中，则可能会在垂直方向上发生屈曲。后一种屈曲模式可能导致灾难性的管道故障，可能与大量漏油和严重的环境破坏相关。对巨变屈曲的担忧促使许多研究人员研究埋地管道的抗抬升力。本文提出的工作的目的是评估各种参数对埋地海底管道抗剧变屈曲的影响。使用专门的有限元软件 ABAQUS，采用数值方法建立 100 m 长嵌入式管道的代表性和可靠的 3D 模型。从埋在含细粉的中等密度沙子中的管道的基线模型开始，在两种情况下探讨了相关参数对抗抬升力的影响：(1) 整个管道长度的抬升，本质上捕获了平面应变 2D (2) 中央中部抬升 20 m。具体而言，研究了由于细粒、管道直径、嵌入深度和直径与壁厚比的存在而导致的土壤表观内聚力的影响。参考实际拉拔和/或有效管道长度对获得的提升力进行归一化。结果表明，在高管道位移的 3D 分析中获得的归一化上浮力与平面应变模型产生的非常一致。模型分析表明，土壤表观黏聚力对抗拔力的贡献显着。研究表明，随着限制水平的增加（由于嵌入深度和/或管道直径的增加），抗拔力增加，而土壤凝聚力对阻力的相对贡献降低。本文将本研究中获得的有限元结果与可用的预测/分析方法进行了比较，并讨论了哪种方法最能捕获数值模型的破坏模式和抗抬升值。