Abstract Understanding of the characteristics of dam-break flows moving along a sloping wet bed can help to timely issue flood warning and risk mitigation. In this study, laboratory experiments are carried out in a large flume for a wide range of upstream water depth, bed slopes and tailwater depth. The water level is recorded and processed to calculate the mean velocity and wave celerity. Results show that the increase of the bed slope will significantly accelerate the wave-front celerity for the downstream dry bed, while the negative wave celerity will decrease. When water depth ratio α ≥ 0.3 (defined as the ratio of initial downstream water depth over the upstream water depth of dam), there are extra negative waves propagating towards the reservoir area after the flow has developed for a period of time. When α ≥ 0.6, there are the Favre waves propagating downstream. The water level and the mean velocity fluctuate due to the influence of the extra negative waves and the Favre waves. Such fluctuant frequency increases with the increase of the water depth ratio. The empirical formulas are obtained for the celerity of the first extra negative wave and the first downstream wave. The variation of wave-front height is very similar under three bed slopes investigated in this study, while the maximum wave-front height occurs when α = 0.2. The present study broadens the understanding of the effects of the bed slope and the tailwater level on the movement of the dam-break flows. Furthermore, experimental results are also compared with some analytical solutions. The validity of the assumptions made during the development of these analytical solutions and their limitations are discussed by comparing with the experimental measurements.

中文翻译：

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河床边坡和尾水对溃坝水流影响的试验研究

摘要 了解沿倾斜湿床运动的溃坝水流特征有助于及时发布洪水预警和风险缓解。在这项研究中，实验室实验是在一个大水槽中进行的，适用于各种上游水深、床坡和尾水深度。水位被记录和处理以计算平均速度和波速。结果表明，床坡度的增加会显着加快下游干床的波前速度，而负波速度会降低。当水深比α≥0.3（定义为下游初始水深与大坝上游水深的比值）时，水流发展一段时间后，有额外的负波向库区传播。当α≥0.6时，有法夫尔波向下游传播。由于超负波和法夫尔波的影响，水位和平均速度发生波动。这种波动频率随着水深比的增加而增加。得到第一个额外负波和第一个下游波的速度的经验公式。本研究调查的三个床坡下波前高度的变化非常相似，而最大波前高度出现在α=0.2时。本研究拓宽了对河床坡度和尾水位对溃坝水流运动影响的理解。此外，实验结果还与一些解析解进行了比较。