白龙江中游泥石流拦砂坝防治效果分析

Control Effect of Check Dams on Debris Flow in the Midstream of Bailong River

为研究白龙江中游地区泥石流拦砂坝的防治效果,通过野外调查和实验分析,对该地区泥石流拦砂坝的运行现状以及拦砂坝对泥石流的调控效果进行了分析。结果表明:①该地区部分泥石流沟泥石流防治情况严峻,多条泥石流沟存在拦蓄库容不足、拦砂坝坝体破坏严重等问题;②通过对该地区拦砂坝上游泥石流回淤坡度的调查,拦砂坝有较好的回淤缓坡功能,并建立起该地区泥石流回淤坡度的经验公式,即I=(0.4~0.85)I0;③通过对泥石流堆积物的颗粒组成进行实验分析,建立泥石流堆积物的平均粒径比、计算重度比来表征拦砂坝对泥石流的调控效果,拦砂坝对泥石流有较好的分选效果,但其拦排临界粒径尚难以准确确定,且其对泥石流堆积物的重度调节作用并不显著。最后,结合该地区拦砂坝出现的一些工程问题,提出了一些防治建议。研究成果可为该地区泥石流治理工程的修建提供一定的参考。

In this paper,the operation status of check dams in the midstream of Bailong River and their control effects on debris flow are examined through field investigation and experiment analysis.Results reveal that:(1)Some debris flow gullies in the study area are faced with severe situation of debris flow control.The storage capacities of some gullies are insufficient,and the check dams are severely damaged.(2)Investigation on the slope gradient of debris flow in the upstream suggest that check dam has a good silting function.An empirical formula for the silting slope gradient is established for this region:I=(0.4~0.85)I0.(3)On the basis of obtaining the grain size of sediment of the debris flow,the ratio of average particle size and the ratio of bulk density of the sediment are established to describe the control effect on debris flow.Check dam has good sorting function for debris flow particles,but its regulating effect on the density of debris flow is unapparent,and the critical particle size is still hard to determine.In addition,some suggestions are put forward to tackle some engineering problems.