梯-潭结构型泥石流排导槽消能特征试验研究

Experimental Study on Energy Dissipation Characteristics of Debris Flow in a Drainage Channel with Step-pool Configuration

梯-潭结构型排导槽是一种适用于大比降沟床条件下的泥石流排导工程措施,因其良好的防治功效和工程价值而具有较好的应用前景。选取泥石流容重、规模和潭深为主要影响因素,通过水槽试验模拟泥石流在梯-潭结构型排导槽中的运动过程。结果表明,潭内表层铺填的砾石在泥石流浆体强烈的紊动和大颗粒冲击碰撞下发生明显的物质交换现象,且排导过渡性泥石流时物质交换现象最为强烈,稀性泥石流次之,粘性泥石流则相对较弱;梯-潭结构型排导槽的消能主要体现在泥石流通过梯-潭结构时泥深变化和加剧紊流两个方面;梯-潭结构的消能效率与潭深呈正相关关系,且消能率基本大于20%,最大消能率可达73.93%。当潭深过大时,梯-潭结构对泥石流表现出明显的拦截作用,虽消能效果明显,但与排导宗旨相悖。而泥石流规模对梯-潭结构消能的影响相对较小,整体呈现规模越小消能率越高的趋势。

The drainage channel with step-pool configuration,which is one of debris flow drainage works and is used in gully with steep gradient,has a good potential application because of its high-performance control effect and engineering value.In order to explore the characteristics of debris flow in a drainage channel with step-pool configuration,debris flow bulk density,scale and depth of step-pool configuration are selected as the main affecting factors and a series of flume experiments are carried out.Debris flow pattern,time-averaged depth and a phenomenon of interchange of materials were investigated along with the characteristics of energy dissipation in this paper.According to the experimental results,the phenomenon was most intense when debris flow with 17 kN/m^3 passed through a drainage channel than the other two.And the energy dissipation is mainly shown in the aspects of flow depth changing and turbulence intensifying.The analysis also indicates that the ratio of energy dissipation increased as depth of step-pool configuration increased and was more than 20% basically.The maximum observed ratio of energy dissipation was 73.93%in the experiment where debris flow bulk density was 14 kN/m^3,scale was 0.5 m^3 and depth of step-pool configuration was 30 cm.However,the step-pool configuration with overlarge depth performed evident trapping sediment which contraries the purpose of transporting sediment.Besides,the energy dissipation decreased with the debris flow scale,which had fewer effect than the other two factors.