Abstract
According to the results of a dynamic prototype test for the surface outlet radial gate on the Jinping high arch dam during the flood discharging process, a novel cause of vibration fundamentally different from the traditional causes of flow-induced radial gate vibration, is analyzed for the first time. Under the condition that the flood is discharged only from mid-level outlets, an accompanying vibration of the surface outlet gate is induced by the vibration of the closely spaced mid-level outlet gates. It is counterintuitive that the most intense vibration occurs when the surface outlet gate is closed and, on the contrary, the vibration is reduced when the gate is opened and subjected to flow excitation. In order to analyze and explain this accompanying vibration phenomenon, a theoretical model is developed based on the conventional theory of passive vibration absorbers. The difference between the proposed and conventional theoretical models is that more complex load and damping conditions are considered, and more attention was paid to the dynamic behavior of the accessory structure. Then, the cause and mechanism for the surface outlet gate vibration is clarified in detail, based on the proposed theoretical model. The comprehensive analysis and mutual verification of the prototype test, theoretical derivation and numerical simulation, indicate that the clarification and the proposed theoretical model is reasonable and accurate. The research reported in this paper will be beneficial for the design, operation and maintenance of the hydraulic gates installed on high arch dams.
Highlights
The intense vibration induced by flood discharge may cause significant damage to hydraulic structures, especially to the accessory structures on the dam body
On the basis of the above prototype test data, it is considered that the dynamic interaction between the hydraulic gate and the high velocity discharge flow causes the vibration of the mid-level outlet gate, and the mid-level orifice gate vibration causes the intense vibration10 ofofthe surface outlet gate
Considering the actual condition for the surface outlet gate vibration of the Jinping hydropower station, more attention should be paid to the accessory structures equipped on the large-scale primary structure and, the subsequent analysis indicates that the primary structure damping and the external force on accessory structure will significantly affect the dynamic response of accessory structures, such as the hydraulic gates
Summary
The intense vibration induced by flood discharge may cause significant damage to hydraulic structures, especially to the accessory structures (e.g., guide walls [1,2], sluice gates [3] and gate piers [4]) on the dam body. To the authors’ knowledge, this vibration amplification effect of a closed hydraulic gate was first observed in the flood discharging process of the Jinping project and has not been reported in the existing literature This severe vibration is not affected by flow excitation, which prompts us to study the cause and mechanism of the vibration of the surface outlet gate from the perspective of structural dynamics. The aims of this article are to clarify the cause and mechanism of surface outlet gate vibration in the Jinping high arch dam, and to establish a theoretical model for the aforementioned vibration so that the vibration amplification effect can be approximately estimated as long as the relevant kinetic parameters are determined This will lay an important foundation and provide significant guidance for the presentation of a vibration reduction method and an optimal design scheme.
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