Ground vibration characteristics induced by flood discharge of a high dam: An experimental investigation

Upstream and downstream ground vibrations induced by flood discharge of high dams potentially cause damage in surrounding buildings and affect the living quality of local populations. Significant ground vibrations and some structural damages have been reported in the downstream area of Xiangjiaba Dam, a large-scale high dam located on Jinsha River, Yunnan, China. To study the characteristics of downstream vibration, a physical hydroelastic model is built to simulate discharge conditions and dynamic characteristics of the Xiangjiaba Dam. Hydroelastic models are traditionally built without special vibration isolation process; however, significant effects of ambient vibrations are observed. Therefore, a vibration isolation system has been built to reduce the effects of background vibration, including isolation trench, flexible connections, reinforced concrete foundation, and reasonable arrangement of water circulation system. High correlation coefficients are observed between hydroelastic model simulation and field measurements, which verifies the effectiveness of simulating the original discharge conditions using the hydroelastic model. Then a prediction model is created to predict downstream field measurements using model simulation data. The predictions generally agree with field observations well. Vibration energy distribution is analyzed among different structural components, which shows that orifices always have the highest energy contribution, and guide walls have significantly higher contribution when discharging through surface orifices. Furthermore, additional influential factors are studied which shows downstream vibrations generally increase with larger orifices openings, higher upstream water levels, and larger rate of flow.