断层作用下管道应变计算有限元模型对比研究

Comparative Study on the FEM Models of Buried Pipeline under Fault Movement

对于穿越活动断层的管道通常采用基于应变的方法进行抗震设计校核。为此,建立管单元、固定边界壳单元、管壳耦合和等效弹簧边界等4种有限元模型,从结果差异性和模型计算效率2方面进行对比分析,得到如下结论:当以不同角度穿越不同位错量走滑断层时,管道4种有限元模型最大轴向应变和最小轴向应变较接近,其中基于壳单元模型计算结果稍保守;在保证计算结果准确性的前提下,采用管壳耦合模型或等效弹簧边界模型可大幅降低计算成本,后者在特殊情况(断层位错量较大)时需加长管段分析长度以保证等效弹簧边界适用性;管单元模型具有最优计算效率,适合大批量计算时使用;管壳耦合模型具有较高计算效率、较广适用性以及较保守的计算结果,适合断层区管道抗震设计时使用。

For seismic design verification of pipelines crossing active fault, methods based on strain are usu-ally taken. The pipe-element model, fixed boundary shell-element model, pipe-shell coupling model and equiva-lent-spring-boundary model have been established. Comparative analyses on result difference and model calculation efficiency have been conducted, and the following conclusions have been drawn: the four kinds of finite element models of pipeline crossing the fault with different angles and different dislocation have close maximum axial strain and minimum axial strain. The result based on shell element model is slightly conserved. On the premise of ensuring the accuracy of the results, the use of pipe-shell coupling model or equivalent-spring-boundary model can signifi-cantly reduce computing costs. In special circumstances ( with a large fault dislocation ) , extension pipe length is necessary to ensure the applicability of equivalent-spring-boundary model. The pipe element model has the best computational efficiency, which is preferable for mass calculation. The pipe-shell coupling model has high computa-tional efficiency, wider applicability and more conservative calculation result, which is suitable for seismic design of the pipeline in fault zone.