泥石流阻塞大河机理试验研究

Experimental Study on Mechanism of Large River Blocking by Debris Flow

通过大型水槽再现了交汇角为90°时高容重黏性泥石流入汇大河的过程,在实验过程中,主要改变泥石流容重和泥石流总量。依据试验资料归纳出了泥石流阻塞大河有3种模式:潜坝壅堵、堰塞坝局部阻塞和堰塞坝全堵,并分析了各自的特点。分析了泥石流阻塞大河的影响因素,分析结果表明:容重影响着泥石流入汇运动的特点和阻塞主河的模式;主河宽度对堵河的影响表现在泥石流的运移距离和主河水力条件改变两方面,大河的河谷宽、水力条件强,难以达到全堵主河状态,常以堰塞坝形式局部阻塞主河;总量对泥石流堵河具有极大的影响,总量越大堵河越严重;当R≥0.80时,堰塞坝固体物质流失严重,上游水位壅高值与堵塞系数呈现指数相关。

Large-scaled flumes were used to reproduce the confluence process of the main river blocked by high density viscous debris flow when the intersection angle was 90°. In the experiment,the amount and the unit weight of debris flow were variants. Based on the experiment data,three types of the river-blocked by debris flow were summarized： total blocking by submerged dam,partly blocking by sand dam and completely blocking by sand dam. Furthermore,their characteristics were analyzed respectively. And the influence factors of the large river blocked by debris flow were analyzed. The analysis results show that： the unit weight of debris flow influences the characteristics of the confluence movement and the river-blocking pattern of debris flow; the influence of the main river width on the river blocking is reflected in the flow distance of debris flow and the change of the hydraulic condition of the main river. Because of the width and the strong hydraulic condition of main river,the main river is difficult to be totally blocked,and is always partly blocked by sand dam. Total volume of debris flow has significant influence on blocking large river,and the rive blocking becomes more serious with the total volume of debris flow increasing. When R is more than or equal to 0. 80,the solid material of sand dam runs off seriously and the value of backwater height of upstream presents exponential correlation with block coefficient.