“阶梯+消力墩”型排导槽调控泥石流性能研究

Regulation Performance of Debris Flow by“Step+Baffle”Drainage Channel

排导槽在泥石流减灾防灾中扮演着重要角色,但以往的排导槽难以解决近些年出现的大坡降沟道泥石流灾害治理难题。为此,提出了一种"阶梯+消力墩"排导槽以期解决这一难题。通过水槽试验,从泥石流流态、密度、颗粒粒径、泥深、速度和冲击力等方面评估3种消力墩体型(正方形、梯形和三角形)排导槽调控泥石流的效果。结果表明:泥石流在排导槽内呈现波状流态,消力墩把泥石流挑向空中,对泥深产生了放大效应,且正方形消力墩放大效果最明显,梯形消力墩放大效应最弱,可以显著降低泥石流流速;泥石流经过"阶梯+消力墩"结构的调控后,在出口处的密度有所降低,固相颗粒粒径减小,且梯形消力墩表现出最强的拦粗排细能力;梯形消力墩上承受的冲击压强大于三角形消力墩上的冲击压强,第1个消力墩上冲击压强最大的体型为正方形消力墩体型,第2、3个消力墩上冲击压强最大的体型为梯形消力墩体型。

The drainage channel plays a key role in the mitigation of debris flow.However,the traditional drainage channels are difficult to consider the problem of debris flow management in a large slope gully occurred in recent years.Therefore,a type of"step+baffle"drainage channel was proposed to deal with this question.Three geometric shapes of baffles(square,triangle,and trapezoid)were designed to test their performances for regulating the flow patterns,flow density and depth,grain size,velocity,and impact pressure based on the flume experiments.The results showed that the debris flow was lifted into the air by the baffles,and a wavy flow pattern generated in the drainage channel.Although the amplification effect on the flow depth was produced by the baffles,it can significantly reduce the debris flow velocity.The amplification effect of the square baffles was the most obvious,and the trapezoidal baffles had the weakest amplification effect.After the regulation of"step+baffle"systems,the density of debris flow and the particle size of solid phase at the exit decreased,and the trapezoidal baffle showed the strongest ability of blocking coarse and discharging fine.The impact pressure on the trapezoidal baffles was larger than that on triangular baffles.The first baffle of square baffle drainage channel endured the largest impact pressure of debris flow.The impact pressures on the second and third baffles in trapezoidal baffle drainage channel were both the largest among the three types of drainage channels.