高拱坝表孔宽尾墩体型参数对泄流能力的影响

Effects of flaring gate piers with different shape parameters on discharge capacity of surface spillway in a high arch dam

高拱坝坝顶较薄,表孔溢流坝面较短,导致宽尾墩应用于高拱坝表孔对泄流能力会产生一定的影响,为探究满足表孔泄流能力设计要求的宽尾墩体型,基于东庄水利工程,采用数值模拟方法,研究宽尾墩俯角、收缩比、墩尾折角、始折点位置等体型参数对高拱坝表孔泄流能力的影响以及泄流能力与过堰水流弗劳德数Fr的关系。研究结果表明,表孔泄流能力随着宽尾墩俯角的减小而减小,随着收缩比的减小而减小,随着墩尾折角的减小而增大,随着始折点位置与堰顶水平距离的减小而减小;提出了表征宽尾墩各类体型参数与堰上水头影响的综合影响系数k综,当k综≥2时,宽尾墩不影响表孔的泄流能力,当k综<2时,随着k综值的减小,宽尾墩对表孔泄流能力的影响逐渐增大;过堰水流Fr沿程变化曲线在宽尾墩始折点上游存在一个折点,该折点处的Fr越大,宽尾墩对表孔泄流能力的影响越小。

The surface spillway is generally short for high arch dams due tothe thin dam crest. Discharge capacity can be affected if flaring gate piers are applied to surface spillway in high arch dams. Numerical simulation was carried out on the basis of the Dongzhuang water conservancy project to explore the flaring gate piers that can meet the design requirements for discharge capacity. The effects of plunge angles,contraction ratios,deflection angles on discharge capacity and the relationship between discharge capacity and Froude number along the surface spillway were studied. The results show that the discharge capacity of surface spillway decreases with the decrease of plunge angles,contraction ratios and the horizontal distance between starting flare and weir crest but it increases with the decrease of deflection angles. A comprehensive influence coefficient k综is proposed to reflect the effect of the shape parameters of flaring gate piers and water head over the weir. For k综≥2,flaring gate piers have no effect on the discharge capacity of a surface spillway. For k综2,the effect on discharge capacity is gradually enhanced with a decreasing k综. There is a knee point on the curve of Froude number along the surface spillway in the upstream of the starting flare. The discharge capacity is less affected by higher Froude number at the knee point.