侧向水流作用下均匀沙休止角变化的试验研究

Experiment study on repose angle of uniform sand under influence of lateral flow

散体沙动水休止角是表征沙丘、沙洲等散体沙堆积体稳定形态的重要特征参数,在岸坡稳定分析、坝前冲刷漏斗形态研究中有着广泛的应用。采用室内试验的方法研究了侧向水流作用下不同粒径天然均匀散体沙水下休止角的变化规律。结果表明:在水流流速超过泥沙颗粒起动流速后,天然散体沙水下休止角随流速增大而减小,且减小的速度随着流速的进一步增加而更加迅速;相同流速条件下,粗颗粒泥沙的水下休止角大于细颗粒,其对流速变化的敏感度也低于细颗粒。基于侧向水流边坡上泥沙颗粒的受力分析,引入相对流速概念,初步建立了侧向水流作用下均匀散体沙动水休止角计算公式及其简化形式。

Dynamic repose angle is a vital parameter that reflects the stability of non-cohesive granular accumulation like dunes and bars. It can also be extensively used to predict slope stability and scoured funnel in front of dams. Flume experiment has finished on the laws of the repose angle of natural uniform non-cohesive sand with different diameters and different lateral flows below water. The results show that the repose angle of natural non-cohesive sand decreases as the flow velocities increase when flow velocity exceeds incipient velocity. When flow velocities are equal, repose angle of the coarse sand is larger than that of the fine sand. The former is less sensitively to flow velocity changes than the latter. Based on the force analysis of sand on the slope in lateral flow environment, and the introduction of relative velocity conception, a dynamic repose angle calculation formula of the uniform non-cohesive sand under influence of lateral flow is established.