水体-结构-地基耦联的拉西瓦拱坝地震响应分析

Seismic Response Analysis of Laxiwa Arch Dam Based on Water-Structure-Foundation Coupling System

以拉西瓦拱坝为研究对象,考虑流固耦合效应以及土体-结构相互作用,依据弹性波理论,利用有限元软件ANSYS建立了拉西瓦拱坝结构附加质量模型和流固耦合模型,分别进行拱坝结构模态分析,研究不同流固耦合模式对拱坝动力特性的影响。分别对无质量地基模型与黏弹性边界模型进行地震波输入,进行线弹性地震响应分析,探讨水体-结构-地基耦联系统相互作用的影响规律。结果表明:拉西瓦拱坝结构工作基频为1. 44 Hz,对应振型为反对称形式;同时考虑库水可压缩性和无限地基辐射阻尼两个因素,拱坝地震响应会降低更多;黏弹性边界模型能够考虑辐射阻尼效应,与无质量地基模型相比,应力幅值降低47. 1%。

Taking Laxiwa arch dam project as the research object, ANSYS was used to establish the additional mass model and the flu- id-solid coupling model of Laxiwa arch dam on the bases of fluid-solid coupling effect, soil-structure interaction and elastic wave theory. These models were set up to analyze the structural mode of the arch dam and the influences of different fluid-solid coupling modes on dynamic characteristics of the dam. The seismic wave time-histories were inputted simultaneously to both the massless founda- tion model and the viscoelastic boundary model in order to analyze the linear elasticseismic responseand discuss the interactive laws of water-structure-foundation coupling system. The results show that the working frequency of the Laxiwa arch dam is 1.44 Hz and it is antisymmetric vibration mode. When the compressibility of reservoir water and the radiation damping of infinite foundation are considered at the same time, the seismic response of the arch dam will be reduced more. Compared with the results of the massless foundation model, the stress response value of the viscoelastic boundary model deerease by 47.1%.