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山洪常常携带大量泥沙进入山区河道,运动的泥沙从水流中吸收能量,增大了水流阻力从而使水位额外升高。本文通过大比降水槽试验模拟该现象,试验结果表明泥沙进入河流后因颗粒间的碰撞、运动吸收能量导致阻力增大,水深增加;水深受携带泥沙粒径、输沙率、床面形态、底坡与水流的影响。最后分析以上的各因素对水流阻力的变化规律,推导出泥沙进入河道情况下山区大比降河流水深的变化,建立起水流挟沙后水深变化的经验表达式。
Floods often carry a large amount of sediment into the mountain river, and the moving sediment absorbs energy from the water flow, increasing the resistance to water flow and thus causing the water level to rise excessively. In this paper, we simulated this phenomenon by the experiment of large-scale sag. The results show that the resistance increases with the absorption of energy due to collision between particles and the water depth after entering the river. The water depth is affected by the particle size, sediment transport rate, Surface morphology, slope and water flow. Finally, the variation of water resistance of the above factors is analyzed, and the change of water depth of large-ratio river in mountainous area is deduced when the sediment enters the river. The empirical expression of water depth change after sediment flow is established.