考虑初始嵌入深度变异性的海底管道整体侧向屈曲分析

Analysis of globally lateral buckling of submarine pipelines considering the variability of initial embedment

海底管道是海洋油气工程的重要组成部分,在高温高压运行状态下易发生整体屈曲,开裂破坏后造成油气泄露。海床土体对管道的侧向抗力是影响其屈曲的关键因素,而管道侧向抗力发挥与初始嵌入深度密切相关。构建了海底管道整体屈曲数值模型,对初始嵌入深度等因素进行不确定性分析,揭示了初始嵌入深度变异性对管道屈曲的影响机制。研究发现:当初始嵌入深度越大、初始缺陷越小时,管道临界屈曲轴力越大,屈曲位移越小;管道嵌入深度变异性的存在会导致管道更易屈曲,并诱发不对称的三阶屈曲或更高阶屈曲;管道嵌入深度在空间上的变异性对屈曲发生概率P(p<p_(det))存在影响,而相关性的改变对管道屈曲影响较小;管道存在屈曲模式转变界限升温,当屈曲升温大于界限升温时,管道发生跳跃型屈曲,反之则发生分岔型屈曲。

As the important parts of offshore oil and gas transportation,submarine pipelines are prone to global buckling under HT/HP conditions,which may lead to cracking and damaging,resulting in fuel leakage.Seabed lateral resistance to pipeline is the key factor affecting the pipeline buckling,which is closely related to the initial embedment of the pipeline.A numerical model of the pipeline global buckling was established and the uncertain analysis about the effect of the initial embedment on the pipeline buckling was made.The results show that when the initial embedment is deeper and the initial imperfection is smaller,the buckling axial force is larger and the pipeline deflection is smaller.The introduction of the pipe embedment random field will cause the pipeline to be more prone to buckling,which may lead to asymmetric third-order buckling or even higher-order buckling.Spatial variation has effects on the probability of buckling P(p<p_(det)),while the effect of the correlation is negligible.It shows that the pipeline has a buckling mode shift limit temperature increment.When the elevated temperature is greater than the limit increment,the pipeline shows snap-through buckling.Otherwise,the bifurcation buckling occurs.