Author(s): Bin Ma; Zhen Yao; Fang Liu
Linked Author(s): Bin Ma, Fang Liu
Keywords: High arch dam; Plunge pool; Vibration of slabs; Modern spectral analysis; Correlation analysis
Abstract: The main features in the aspect of flood discharge of those large water resources and hydropower projects located in narrow valleys in China are high head, large flow rate and strong discharge power, and then the problem from the safety of the flood discharge is quite prominent. The safety of protecting structure in high dam plunge pool is the key to success or failure of energy dissipation, there is no lack of the destructive example at home and abroad. This paper makes an insight into the plunge pool of high arch dam. The vibration of slabs of the Ertan, Laxiwa and Jinping-1 plunge pool are analyzed according to prototype observation data by applying the modern spectral analysis method and correlation analysis method. The properties in the frequency extent and the correlation of concrete slabs in plunge pool of high arch dam are discussed. The results show that the dominating frequency of different measuring points under the safe operation state is maintained in the range of 0~2Hz, which belongs to the range of flow fluctuating frequency. Therefore, each measuring point is forced vibration under the flow loads. In the case of vibration of each measuring point under the different working conditions, on the downstream of impacting zone of jets, the dominating frequency of concrete slab in plunge pool is not only related with flow discharge and is closely related to the location of the helical flow at the bottom of the plunge pool. Their specific relationship depend on the different working conditions. And the dominating frequency of measuring point in the different concrete slabs is very close under the same working conditions. In the aspect of correlation, the change trends of each measuring point under the different working condition are essentially consistent. The vibration condition of the measuring point in the impacted area is more complicated under the different working conditions. While the vibration mechanism of the helical flow area is relatively simple, for the same reasons and have a good correlation. Due to the current burble gradually collapse in the diffusion area, the flow show irregular turbulent motion and have a bad correlation.
Year: 2013