Study on the Mean Velocity of Viscous Debris Flows
Study on the Mean Velocity of Viscous Debris Flows
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DOI：
10.11867/j.issn.1001-8166.2008.05.0524
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发表时间：
2008-05
期刊：
影响因子：
--
通讯作者：
Yu Bin
中科院分区：
文献类型：
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作者：
Yu Bin
粘性泥石流是最常见、最危险的泥石流。泥石流的速度是泥石流动力学参数中最重要的参数，准确、方便地计算粘性泥石流的速度非常重要。不同地区泥石流的阻力差异较大：低速泥石流区阻力大；流速高的泥石流区阻力小。目前粘性泥石流速度方程在各种阻力区都不好。不同区域：低阻力泥石流不对称系数大；高阻力泥石流不对称系数小。利用泥石流不对称系数可以对泥石流阻力特性进行准确分类，通过不对称系数得到粘性泥石流的阻力规律。通过一系列现场观测数据，得到粘性泥石流平均速度经验方程。由不对称系数、底坡度和水流水力半径计算出速度。对于泥石流高阻力和低阻力区域均适用该经验方程对于泥石流和粘性泥石流其他现场观测数据的测量速度具有良好的一致性。流动弗劳德数是决定流动状态：超临界流还是亚临界流的因素。普通粘性泥石流为超临界流，少数为亚临界流，少数为密度过大的慢速泥石流。该经验方程对于普通超临界粘性泥石流效果较好，但对于泥石流密度较大的慢速流则较差。在泥石流评价与防治中，可采用平均速度方程计算泥石流扇上游通道内粘性泥石流的速度，同时计算泥石流扇上粘性泥石流的速度时偏大，对慢运动泥石流不利，但在泥石流评价与防治中可以忽略慢运动。
Viscous debris flows is the most regular and dangerous debris flows.The velocity of debris flow is the most important parameter in the dynamics parameter of debris flow.It is very important to calculate the velocity of viscous debris flow exactly and easily.The resistance of debris flow is quite different at different area: high resistance of debris flow area with low velocity;low resistance of debris flow area with high velocity.All equations of velocity of viscous debris flow at present are not good at all kinds of resistance area.The asymmetric coefficients of debris flows are quite different in different area: large asymmetric coefficients of debris flow with low resistance;small asymmetric coefficients of debris flow with high resistance.The asymmetric coefficients of debris flow could be used to classify resistance characteristics of debris flow accurately and the resistance law of viscous debris flows was got by asymmetric coefficients.By a series field observation data,an empirical equation of mean velocity of viscous debris flow was got.The velocity calculated by the asymmetric coefficients,bottom slope and hydraulic radius of flow.It is good at both high resistance and low resistance area of debris flows.It is good consistent for the measuring velocity of otherwise field observation data of debris flow and viscous mudflow by this empirical equation.The Froude number of flow is the factor of flow status: supercritical flow or subcritical flow.Ordinary viscous debris flows are supercritical flows,minorities are subcritical flows,and few are slow-motion debris flows which have too large density.The empirical equation is excellent at ordinary supercritical viscous debris flow,but it is bad for the slow-motion flow with large density of debris flow,and it is gentle large for the subcritical viscous debris flow.In the evaluation and prevention of debris flows,the mean velocity equation could be used for the velocity calculated of viscous debris flow in the channel at the upstream of the debris flow fans.At the same time,it is gentle large for the calculating the velocity of viscous debris flow on the debris flow fans.It is bad for the slow-motion debris flow,but the slow-motion could be ignored in the evaluation and prevention of debris flows.