考虑海底管线初始侧向变形的低阶模态

温度应力下海底管线的整体屈曲是海底管线设计中的关键问题之一，不埋或半埋的海底管线较易发生水平向整体屈曲。海底管线会因为制造的缺陷或铺设的原因而具有初始变形，即初始侧向变形。研究了初始侧向变形对海底管线整体屈曲的影响，应用小变形理论建立了单拱侧向变形和反对称双拱侧向变形管线发生低阶模态水平向整体屈曲的理论分析方法，结合工程实例分析了初始侧向变形形态、侧向变形幅值以及地基土体强度特性对管线水平向整体屈曲的影响。结果表明，初始侧向变形的存在使管线更易发生整体屈曲；而反对称双拱侧向变形比单拱侧向变形更易引起管线整体屈曲；随初始侧向变形幅值的增加管线发生整体屈曲所需要的温差降低，且整体屈曲变形形态有所改变管土间摩擦系数的增加会提高管线发生整体屈曲的温差，从而提高管线抵抗整体屈曲变形的能力。

Study on low-order global lateral buckling of submarine pipeline with initial lateral deformation

Global lateral buckling analysis of submarine pipeline under thermal stress plays an important role in pipeline design. Unburied pipelines tend to experience lateral buckling. Theoretical analysis methodologies of pipeline with initial lateral deformations of one-arch and anti-symmetric two-arch are obtained by employing the small deformation theory. Based on a practical project, the influences of the lateral deformation shape, amplitude of lateral deformation, and sub-soil properties on the pipeline thermal lateral buckling are analyzed in detail. Analysis of results shows that the initial lateral deformation will accelerate the pipeline buckling procedure. The initial buckling temperature difference of the pipeline with the anti symmetric two-arch initial lateral deformation is lower than that of the pipeline with one-arch initial lateral deformation.With the increasing of lateral deformation amplitude, the initial buckling temperature difference of the pipeline decreases and the buckling topology of the pipeline changes. With increasing of the friction coefficients between the pipeline and the subsoil, the initial buckling temperature increases, which makes the pipeline much safer.