地震动空间相关性对地下连续管线的影响

Effect of spatial coherence of seismic ground motions on underground continuous pipeline

地下管线地震反应通常用波动理论求解,输入的地震动在空间上是完全相关的。台阵记录分析结果已证实,地震时地面上各点的地震动是部分相关的。地震地面运动的这种性质对地下连续管线的影响还不十分清楚。利用随机振动理论中的虚拟激励法计算了均匀介质中地下连续管线纵向和横向地震响应,给出了局部效应、相干效应对地下连续管线的影响。分析结果表明,忽略地面运动的部分相关性会给出不安全的结果,不同的部分相干模型对地下连续管线的影响不同。因此,实际计算时应考虑地震动的部分相关性,慎重选取部分相干模型。

Seismic response of underground pipelines is usually calculated by wave propagation theory, in which spatially full coherence of seismic ground motions is assumed. The analysis of data recorded at dense instrument arrays has confirmed the partial coherence of seismic ground motions at different stations. The effect of the partial coherence of seismic ground motions on underground continuous pipeline is not very clear. In this paper, seismic responses of underground continuous pipeline in both longitudinal and lateral directions in uniform medium are studied by the pseudo-excitation method in random vibration theory, and then the impacts of locality effect and coherence effect on underground continuous pipeline are analyzed respectively. The results show that it may be unsafe without consideration of the partial coherence of seismic ground motions, and different coherence models lead to different results. It is suggested that the partial coherence of seismic ground motions should be considered, and the coherence models should be chosen cautiously.