高拱坝表孔及中孔挑流水舌上下碰撞作用下基岩冲刷

Limiting scour depth by the interaction of water jets from surface outlets with jets from mid-level outlets in high arch dams

分析了表孔及中孔挑流水舌上下碰撞能量损失、 3 -D扩散和漏碰等水力特点 ,用动量方程和水舌空中扩散宽度沿程变化规律导出 3 - D碰撞流速、碰撞效率和碰撞能量损失 ,得出碰撞最佳水力条件。分析碰撞水舌对基岩冲刷特点 ,提出表、中孔水舌上下碰撞作用下基岩冲刷平衡深度估算方法。小湾表孔、中孔碰撞工况下基岩冲刷试验表明 ,预报值和试验值在各级库水位下基本吻合。

A hydraulic model was developed to analyze the interaction between two interactivity jets to reduce the scour depth due to jets from high arch dams. The model was used to analyse the hydraulic characteristics such as energy loss, three dimensional diffusion and leakage collision, and to calculate the velocity magnitude and direction after the interaction and the energy loss by the momentum equation and the jet width. Based on the model above, a hydraulic method to calculate the scour depth was proposed. The calculated results compare well with experimental data from the Xiaowan Project for various water levels and river rock scales.