Abstract
Dam is set in large hydropower station. Cushion pool is built behind the dam for the flood discharge and energy dissipation of the reservoir. Operation of flood discharge and energy dissipation for some time, Cushion pool is dewatering and structure safety of which is study, then cushion pool is filled. Temporary dewater and filled system is used by previous engineer, but is arranged and controlled hard. Based on need of the cushion pool dewatering and filling, for an example of Baihetan hydropower station, necessity and feasibility are study. Then a permanent dewatering and filling system is designed for cushion pool. Design principle and arrange method are described. Many technical difficulties are study and resolved such as effect of valley deformation on the control system of dewatering and filling, demand of dewatering and filling device parameter, performance quota formulate based on large water level amplitude, protective measures in the working condition of much silt on the downstream and humidity in the equipment room of the second-dam and project of dewater drainage outlet under the water. By gravity drainage and filling based on water level difference and pump drainage, much electric energy is saved and personnel operating environment and working conditions are improved.
Highlights
Cushion pool is an energy dissipation protection building behind high drop arch dam, which can prevent erosion damage of dam foundation and protect the safety and stability of dam
When the arch dam is in flood discharge operation, The bottom structure of the water cushion pool may be eroded by the current, so it is necessary to carry out regular pumping maintenance on the cushion pool
Many hydropower stations have been built in China, such as Xiluodu [1], [2], [3], Ertan [4], [5], [6], Wudongde [7], [8], Jinping I [9], [10], [11], etc., a temporary dewatering and filling system was used to repair the water cushion pool which is dewatered and empty
Summary
Four processes are included in the operation mode of dewatering and filling system of cushion pool: automatic drainage of cushion pool, pumping and discharging clear water, backwashing of water collection basin and drainage main pipe of cushion pool, pumping and discharging sewage of cushion pool, which are as follows. When the water level in the downstream river is low, the automatic water dewatering and filling system in dewatering and filling system of the cushion pool is used to discharge dropsy in the cushion pool to the downstream, the energy consumption of the system operation will be reduced. The indoor operation valve of gravity water dewatering and filling valve are opened, and the cushion pool is connected with gravity water dewatering and filling pipe connected with downstream river channel. The overhaul water inlet main pipe and the water collecting basin are flushed by using the water pressure of the downstream tail water higher than the water level in the upstream cushion pool. The remaining accumulated water in the cushion pool is drained by the pumping system
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