近年来调水工程数量逐渐增加,大跨输水结构抗震性能问题愈发突出。以滇中引水工程中龙川江倒虹吸为研究对象,建立三维有限元模型,将水平偏振横波(SH波)水平入射、斜入射以及垂直入射V形河谷场地计算结果作为地震动输入,分析地形效应引起的差异地震动对该大跨输水倒虹吸地震响应的影响,并与一致激励下结果进行对比。结果表明:考虑地形效应的差异地震动对结构重要构件受力和变形影响显著,结构不同构件表现不同,钢管、墩柱等构件横向受力和变形趋势呈现为:水平入射＞斜入射＞一致激励＞垂直入射,而差异地震动作用引起拱圈横向内力减小;结构刚度变化位置对差异地震动作用更加敏感,大跨度输水倒虹吸结构抗震设计有必要考虑地形效应及地震动入射角度的影响。

The seismic performance of large-span water transfer structures has become increasingly prominent with the growing number of water transfer projects in recent years. In this paper, the effect of differential ground motion caused by topographic effects on the seismic response of Longchuanjiang large-span water transfer inverted siphon in Central Yunnan Water Diversion Project is examined by establishing a three-dimensional finite element model with the calculated results of SH wave horizontal incidence, oblique incidence and vertical incidence as ground motion inputs. The results are compared with those under uniform excitation. Results manifest that differential ground motion in consideration of topographic effect has a significant impact on the force and deformation of important structural elements, and different structural components behave differently. The transverse force and deformation of steel pipes, piers and other elements under horizontal incidence is the largest, followed by that under oblique incidence, uniform excitation, and vertical incidence in sequence, while the differential seismic effect causes a reduction in the transverse internal force of the arch ring. The location of structural stiffness change is more sensitive to differential seismic effect. In conclusion, it is necessary to consider the topographic effect and the influence of incidence angle of ground motion in the seismic design of large-span water transmission inverted siphon structures.