藏东南部泥石流堵河试验研究

Experiments of debris flow damming in Southeast Tibet

通过模型试验对泥石流入汇主河后堵塞坝形成过程以及堵塞坝体溃决后主河河床形态特征进行了研究。实验历时3个月,共13组试验。在支主沟交汇角为90°的情况下,通过改变支沟泥石流容重、支主沟的流量比和动量比,建立了泥石流堵河的判别公式,当r>1 001.16时容易发生堵河现象,并对培龙沟两次泥石流堵河事件进行了判定;定义了主河的束窄率S与主河流速变异系数Fv,并发现了主河的束窄率与支主沟动量比之间存在线性关系;主河稳定后的平均宽度与流速变异系数之间存在幂的关系。该实验能够较好地模拟泥石流堵塞坝形成的过程,结果比较合理,并为泥石流灾害的防治提供了相应的理论基础。

In this paper, the formations of jammed dam by debris flow＇s injection and the influences on mainstream＇s riverbed by subsequent outburst of the dam have been discussed based on a model test. The experiments lasted 3 months, together with 13 groups of tests in all. As the junctional angle is equal to 90, the critical index of jammed dam are established through the adjustments of density of debris flow, discharge ratio and momentum ratio between branch gully and main river; the jammed dams are easily formed when r〉 1 001.16; the two events of damming in Peilong gully （1984,1985） have been discriminated. The shrinkage ratio of main river S and coefficient of velocity variation Fv have been defined, and the results indicate that there is a linear relationship between the momentum ratio and the shrinkage ratio of main river, and also an exponential relationship between the ultimate average width of main river and the coefficient of velocity variation. This model test can simulate the process of damming of debris flow, and the results that offer theoretic basis for the mitigation of debris flow are comparatively reasonable.