考虑不同库水耦合模式的拱坝振动特性分析

为探讨不同库水模型对拱坝结构动力特性的影响,结合拉西瓦工程实例,分别建立附加质量模型与流固耦合(fluid solid interaction,简称FSI)系统耦合模型进行动力特性分析,并将仿真结果与依据小波阈值-经验模态分解联合滤波的随机子空间(stochastic subspace identification,简称SSI)法辨识结果进行对比。结果表明:两种模型均可反映结构的振动特性,附加质量模型计算结果与辨识结果的频率误差为0.41%~7.55%;FSI系统耦合模型计算结果误差为0.09%~3.19%,且同阶次频率误差均比附加质量模型小,相邻阶次的频率间隔相对稳定,弥补了附加质量模型的模态缺失现象。FSI系统耦合模型在模拟阶数和精度方面都优于附加质量模型,能更全面、准确地反映坝体振动信息,可在拱坝结构动力特性分析中推广应用,亦可作为后续拱坝结构损伤诊断研究的基准有限元模型。

Dynamic Characteristic Analysis of Arch Dams with Different Forms of Reservoir Water Coupling

In order to study the influence of different reservoir water models on arch dam structural dynamic characteristics, an added masses model and fluid solid interaction(FSI) system model of a Laxiwa arch dam were set up. The results of finite element simulation were compared with the identification results of stochastic subspace identification (SSI) based on wavelet threshold combined with the empirical mode decomposition (EMD) filtering method. The comparison shows that the structural dynamic characteristics were reflected by both coupled models, and the frequency error margin for the added masses model calculation results to the identification results was 0.41%~7.55%, while that of the FSI system coupled model was 0.09%~3.19%. The FSI system model was superior to the added massed model with a smaller error at each frequency order. Additionally, the frequency space of contiguous order of the FSI system model was relatively stable. This study shows that the FSI system coupled model can reflect the arch dam vibration information comprehensively and accurately in terms of simulation order number and precision. The FSI system coupled model can be applied in the dynamic characteristics analysis of arch dam structure, and used as a reference of the finite element model in the research of diagnosing arch structural damage.