基于量纲分析的泥石流堰塞坝高度特征研究

Research on height characteristics of debris flow barrier dam based on dimensional analysis

泥石流堵河堰塞坝高度直接决定了堰塞湖库容与溃决洪水流量,是影响上、下游受灾程度的关键因素。将影响泥石流堵河的主要参数组合成为4个无量纲因子(体积浓度因子、体积因子、黏粒含量因子、流速比),并通过室内水槽实验研究了无量纲因子作用下高容重泥石流完全堵河形式及堰塞坝高度特征,还构建了直角交汇情况下堰塞坝沟口高度和堵河高度的预测模型。结果表明:(1)根据主支流量比Q、流速比U的乘积可进一步将泥石流完全堵河模式划分为顶冲对岸式(Q×U≤0.045)和连续推进式(Q×U>0.045)两种形式。(2)对泥石流堰塞坝高度的分析表明,泥石流沟口高度与体积浓度因子、体积因子呈正比,与流速比呈反比;泥石流堵河高度与体积因子呈正比,与体积浓度因子、流速比呈反比,而在黏粒含量因子影响下,泥石流沟口高度和堵河高度均呈现先增后减趋势。(3)构建的模型预测精度良好,实际案例与模型对比相结合的方法验证结果显示,预测模型具有一定适用性。研究成果可为泥石流堵河的防灾减灾工作提供参考。

The height of debris flow barrier dam directly determines the reservoir capacity and outburst flood flow,which is a key factor affecting the disaster-stricken degrees of both upstream and downstream areas.Main parameters influencing debris flow blocking river are grouped into four dimensionless factors(the volume concentration factor,the volume factor,the clay-content factor,and the flow velocity ratio).Through indoor flume experiments,complete blocking forms of high density debris flows and height characteristics of barrier dams under the influence of these dimensionless factors are studied.And then a predictive model for gully height and river blockage height of debris flow dams under right-angle confluence conditions is established.The results show that:(1) According to the product of two dimensionless factors,namely the main-tributary flow ratio(Q) and the flow velocity ratio(U),the complete-blockage modes of debris flows can be further classified into two forms,the "opposite-bank top rushing" type(Q×U≤0.045) and the "continuous advancing" type(Q×U>0.045).(2) The analysis of the height of debris flow barrier shows that the height of debris flow gully is proportional to both the volume concentration factor and the volume factor,and is inversely proportional to the flow velocity ratio.The height of debris flow blocking river is proportional to the volume factor,and is inversely proportional to the volume concentration factor and the flow velocity ratio.Under the influence of the clay content factor,the height of debris flow gully and the height of blocking river show a trend of increasing first and then decreasing.(3) The predictive model demonstrates good prediction accuracy and is validated through comparison with real-world case studies.The results show that the predictive model is applicable.The research findings can provide valuable reference for disaster prevention and mitigation measures related to debris flow river blockage.