蒋家沟泥石流阻力的无量纲参数分析  

Dimensionless Analysis of Resistance of Debris Flow in the Jiangjia Gully,China

作　　者：苗绿 马超[1] 吕立群 MIAO Lyu;MA Chao;LYU Liqun(School of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]北京林业大学水土保持学院,北京100083

出　　处：《山地学报》2021年第4期515-523,共9页Mountain Research

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0902)。

摘　　要：流速作为泥石流防治工程的重要参数之一,泥石流阻力的大小对其计算过程至关重要。但关于泥石流内部应力变化对阻力影响的研究甚少。本文利用东川蒋家沟泥石流观测数据,反算曼宁系数来表达泥石流运动过程中受到的综合阻力,并利用拜格诺数、萨维奇数和摩擦数三个无量纲参数,分析它们和阻力之间的关系。结果表明:粘性和稀性泥石流的拜格诺数和萨维奇数均小于临界值;粘性泥石流摩擦数大于临界值,而稀性泥石流摩擦数小于临界值。因此,颗粒接触摩擦对粘性泥石流运动的贡献程度超过了粘性剪切应力和颗粒碰撞产生的离散应力,粘性剪切应力对稀性泥石流运动的贡献程度超过了颗粒碰撞产生的离散应力和颗粒接触产生的摩擦应力。蒋家沟粘性泥石流和稀性泥石流阻力与拜格诺数、萨维奇数的相关性较弱,与摩擦数关系非常密切,且随着摩擦数的增大综合阻力不断增大。水石流的相对流速随流深的增大而增大,但是粘性泥石流和稀性泥石流的相对流速随流深的增大而减小。本研究结果有望加深对泥石流阻力规律的认识。Velocity is a key parameter of debris flow control engineering,and the value of debris flow resistance is very important to its calculation process.However,there are few studies on the effect of internal stress change of debris flow on resistance.In this work,the observed data of debris flow at the Jiangjia gully in Dongchuan,Yunan province,China were used to back estimate the Manning coefficient,which is an indirect value expressing the comprehensive resistance property.Three dimensionless parameters,i.e.,Bagnold number,Savage number and friction number were used to analyze the relationship between resistance and Manning coefficient.The results show that:the values of Bagnold number and Savage number were all less than the critical value,but the friction number of viscous debris flow was greater than the critical value,and the friction number of diluted debris flow was less than the critical value.Therefore,the contribution of grain contact friction to the motion of viscous debris flow exceeded the inertial stress and viscous shear stress.The contribution of viscous shear stress to the movement of a diluted debris flow exceeded the dispersive stress from inertial grain collision and the friction stress caused by grain contact.The resistances of viscous-and dilated debris flow had a weak correlation with the Bagnold number and Savage number,and were closely related to the friction number.As the Friction number increased,the comprehensive resistance kept increasing.The relative average velocity of stony flow increased with the relative flow depth,but the relative average velocity of viscous debris flow and diluted debris flow decreased with the relative flow depth.The results of this study are expected to deepen the understanding of debris flow resistance.

关 键 词：泥石流阻力 流速 曼宁系数 蒋家沟 

分 类 号：TV144[水利工程—水力学及河流动力学]