“陡坡+跌坎”式消力池板块稳定特性试验研究

通过大比尺(1∶40)物理模型,对某大型水电工程溢洪道"陡坡+跌坎"式消力池这一新型消能工底板稳定性进行了试验研究,得到了水跃完全或部分发生在陡坡段时,消力池不同位置板块的脉动压力、板块上举力频幅特性的分布规律与特征.试验表明水跃跃首部位始终是板块最易失稳区域,当单宽流量达到一定值后,跌坎下一段区域也是失稳重点关注区.对试验结果深入分析后表明:水跃跃首区域上举力均方根大致为脉动压力均方根0.55倍,其它区域为0.2倍,水跃跃首区域最大上举力大致为4.2倍脉动压力均方根,其它区域为1.5倍.揭示了此消能工上举力与脉动压力点面转换指标、底板稳定控制指标与挑跌流消力池的一致性;而消力池平底段采用透水底板可有效降低板块上举力,减小响应趋势基本呈指数分布,并与开孔率呈正比关系.

Experimental Study on Stilling Basin with Step-down for Floor Slab Stability Characteristics

Floor slab stability of stilling basin with step-down was studied by using a 1∶ 40 physical model.With hydraulic jump occurring in the slope,distribution characteristics of fluctuation pressure and lifting load in the stilling basin was obtained.It was found that the first location of hydraulic jump with the large fluctuation pressure was most prone to instability.The position under step-down was also an instable area when the single-wide discharge reached a certain value.Further analysis indicated that the root-mean-square(RMS)of lifting load was about 0.55 times than that of fluctuation pressure in the first region of hydraulic jump,0.2 times than that of other regions;the biggest lifting load was about 4.2 times than RMS of fluctuation pressure,1.5 times than that of other regions.The results revealed that the control indicator of stilling basin with step-down was consistent with deflecting and drop stilling basin;lifting load was effectively reduced by using permeable floor slab,and decrease trend was basically exponential distribution with increasing opening ratio.