三峡工程溢流坝掺气减蚀研究

Study on Anti-corrosion by Air Entraining for the Overflow Dam of TGP

三峡工程最大水头113m，溢流坝面最高流速达35m／s，对泄流面平整度要求很高，施工很难作到。为方便施工和溢流面不发生空蚀，研究采用掺气槽。结合国内外已建工程，尤其是乌江渡工程的经验，三峡工程表孔选用组合式掺气槽，其面积取6．8m2，槽深1．2m，挑坎高0.8m，通气孔直径1．3m，槽内负压值667mm水柱，通气孔布置在两侧闸墩上。深孔掺气槽参考龙羊峡水电站的突跌形式，弧门下游秩差2．0m，通气孔直径1．0m，设在两侧边墙上。

The maximum water head of the Three Gorges Project(TGP) is 113 m and the maximum flow rate in the overflow dam face will amount to 35 m/s. It is very difficult to meet its requirement of smoothness in construction of the overflow dam face. To facilitate its construction and to prevent from occurrence of cavitation on the surface of the overflow dam, it is studied to adopt air entraining trough. By using experiences of built projects of the same kind both at home and abroad, especially the Wujiangdu Hydropower Station, the combination type air entraining trough is to be adopted for the high-level outlets of TGP. The air entraining trough has an area of 6. 8 m2,a depth of 1. 2 m and a sill 0. 8 m high. The suction water column in the trough is 667 mm high. Vent openings,with a diameter of 1. 3 m,will be arranged in piers of both sides. Sudden drop shape adopted in the Longyangxia Hydroelectric Project is used for reference in designing the air entraining trough for deep outlets. The drop in water head is 2 m in the downstream of segmental sluice gate. The vent openings, with a diameter of 1.0 m,are located in the sidewalls of both sides.