阶梯-深潭结构对沟道稳定性的作用机制

阶梯-深潭结构是山区河流中典型的高效消能结构, 以消耗水能、增加阻力的方式提升沟道稳定性。通过水槽试验模拟沟道冲刷, 探究阶梯-深潭结构稳定沟道的机制及效果, 为山区河流消能减灾和稳定河床提供科学和技术参考。结果表明: 阶梯-深潭结构能有效消耗水流能量、抑制泥沙输移和提升水流阻力, 从而有效控制河床下切和边坡破坏; 在阶梯-深潭结构的作用下, 沟道的Darcy-Weisbach系数约增加为无结构条件下的4倍, 时均输沙率降低20%~66%, 但随着流量的增大, 阶梯-深潭稳定沟道的效果降低; 阶梯高度与长度比(0.1)相同时, 结构提升沟道稳定性的效果接近。阶梯-深潭结构自身的稳定是其稳定沟道的关键条件, 实际应用过程中需防止结构发生逐级破坏。

Mechanism of the step-pool structure on channel stability

The step-pool structure is a typical riverbed structure with efficient energy dissipation in mountain rivers, which promotes channel stability by consuming flow energy and increasing resistance. Channel erosion was simulated by flume experiments to explore the mechanism and effect of the step-pool structure on channel stability, to provide a scientific and technical reference for energy dissipation and disaster reduction in mountain rivers. The results show that the step-pool structure can effectively consume flow energy, inhibit sediment transportation and improve flow resistance, thus effectively controlling stream bed incision and slope failure. With the step-pool structure, the Darcy-Weisbach coefficient of the channel increases by approximately 4 times as much as that in tests without this structure, and the time-averaged sediment transportation rate is reduced by 20%—66%, however, the effect of the step-pool structure in stabilizing the channel bed decreases with increasing flow discharge. With same height/length of the steps (0.1), the structure shows a similar effect in improving channel stability. The stability of the step-pool structure is the key condition of channel stability, and it is necessary to prevent the structure from being damaged step by step in practical application.