ABSTRACT

For underground structures with large spans, such as buried pipelines, the seismic motions may vary not only at distinct horizontal locations due to the wave passage, incoherence and local site effects; but also at different vertical soil depths owing to the site amplification effect. This paper numerically investigates the influences of underground spatially correlated earthquake motions (USCEMs) on the seismic behaviors of large-span buried pipelines. To accomplish this task, the widely used buried gas steel pipeline of API X65 is chosen as a case study and the corresponding three-dimensional finite element (3D FE) model is created using the ABAQUS software, which accounts for the soil-pipe interaction (SPI) by the beam on nonlinear Winkler foundation (BNWF) model. The three-dimensional USCEMs for the nonlinear time-history analyses of the buried pipeline are stochastically synthesized based on the computed underground transfer functions of local sites. A total of 11 analysis cases associated with different spatial variability parameters of USCEMs (i.e. seismic excitation type, incoherence loss, local site condition and seismic motions at different soil depths) are considered. Based on increment dynamic analysis (IDA), a parametric study is carried out to comprehensively examine and discuss the influences of different spatial variability parameters on the seismic responses and critical operable capacity of the exemplar buried pipeline by comparing the analysis results of different cases. Numerical results demonstrate that these influencing factors can impact the seismic behaviors of the exemplar buried pipeline in different degrees and cannot be neglected in the seismic analysis. This research can serve as a vital reference for the seismic performance assessment and design of large-span buried pipelines.

摘要

对于大跨度的地下结构，例如埋地管道，地震运动可能不仅在不同的水平位置由于波通过、不相干和局部场地效应而发生变化；而且由于场地放大效应，在不同的垂直土壤深度也是如此。本文数值研究了地下空间相关地震运动（USCEMs）对大跨度埋地管道地震行为的影响。为了完成这项任务，选择广泛使用的 API X65 埋地燃气钢管作为案例研究，并使用 ABAQUS 软件创建了相应的三维有限元 (3D FE) 模型，该模型考虑了土壤与管道的相互作用。 SPI）由梁上非线性温克勒基础（BNWF）模型。用于地下管道非线性时程分析的三维 USCEM 是基于计算的局部站点地下传递函数随机合成的。总共考虑了与USCEMs不同空间变异参数（即地震激发类型、不相干损失、当地场地条件和不同土壤深度的地震运动）相关的11个分析案例。基于增量动态分析（IDA），通过对比不同案例的分析结果，进行参数化研究，全面考察和讨论不同空间变异参数对示范埋地管道地震响应和临界可运行能力的影响。数值结果表明，这些影响因素可以不同程度地影响示范埋地管道的抗震性能，在抗震分析中不可忽视。该研究可为大跨度埋地管道的抗震性能评估和设计提供重要参考。