白龙江甘家沟泥石流过坝堆积物力学性能分析

Mechanical Properties of Debris Passing Through Check Dam in Ganjia Gully in the Midstream of Bailong River

白龙江流域是我国泥石流危害最严重的地区之一,泥石流沟分布密度和泥石流发生频率居全国首位,尽管多次治理,但仍然造成了大量的人员伤亡和财产损失。以甘家沟为研究对象,通过野外实地调查,在分析防治工程现状的基础上,通过颗分试验、流变试验和直剪试验,对比分析了坝上游和坝下游泥石流堆积物的颗粒级配变化情况、浆体流变特性与抗剪强度等性能指标。结果显示:实体拦砂坝存在调节泥石流颗粒粒径作用,但调节效果不显著;拦砂坝的拦挡作用会改变泥石流的力学性能;粒径调节作用较显著的坝体,其坝下游堆积物浆体的剪切应力小于坝上游堆积物浆体的剪切应力,坝下游堆积物抗剪强度略大于坝上游堆积物抗剪强度;泥石流颗粒级配的差异是影响其流变特性与抗剪强度的重要原因。该研究结果对今后泥石流工程坝型选择与参数设计具有一定的参考意义。

Bailong River drainage basin is an area subjected to the most severe debris flow hazard,with debris gully density and debris flow frequency ranking top in China. Despite many treatments,debris flows have caused large casualty and property losses. In this paper,the current engineering mitigation works in Ganjia gully of Bailong River basin were analyzed through field investigation,and on this basis,the particle gradations,rheological behaviors,and shear strengths of debris deposits in the upstream and downstream of check dam were compared through particle size test,rheological test and direct shear test. Results suggest that check dam plays an insignificant role in adjusting the particle size of debris flow,but apparently alters the mechanical properties of debris flow. The shear stress of debris deposit slurry in the downstream of check dam is smaller than that in the upstream; while shear strength in the downstream is slightly larger than that in the upstream. In addition,the difference in grain size distribution of debris flow is an important factor that affects the rheological properties and shear strength. The results could be used as reference for the type selection and parameter design of check dam.