双峰型非均匀沙推移运动特性及输移规律  

Movement characteristics and transport laws of the bimodal bed load

作　　者：孙东坡[1] 刘明潇[2] 王鹏涛[1] 李国栋[2] 赵亚飞[1] 董明家[1] 

机构地区：[1]华北水利水电大学水利学院,河南郑州450045 [2]西安理工大学西北旱区生态水利工程国家重点实验室培育基地,陕西西安710048

出　　处：《水科学进展》2015年第5期660-667,共8页Advances in Water Science

基　　金：国家自然科学基金重点资助项目(51039004);国家重点基础研究发展计划(973计划)资助项目(2011CB403305)~~

摘　　要：采用图像识别与推移质动态监测技术,开展基于双峰型非均匀推移质的系列水槽试验。通过引入反映床面粗糙度、粘性底层特性与颗粒非均匀度η(粗细比)的综合水流强度函数Ψb、特征弗劳德数Frb,系统研究了不同水流强度与床沙组成条件下的推移质输移特性以及颗粒非均匀度对输沙率的影响。通过对关键因子的辨识与量纲分析,提出了双峰型非均匀推移质输移模式,建立了基于近壁特征因子的水流强度Ψb与非均匀推移质输移强度Φ'的函数关系。对双峰型底沙输移机理的分析表明,非均匀沙的组成特征使得η成为影响Φ'的重要参量;正是细粒对粗粒的解怙作用对粗沙运动产生重要影响,使推移质输移率与颗粒非均匀度间呈现驼峰关系,峰值对应的粗细比ηc约为3∶7。The non-uniform bed load transport is a complicated coherent physical process of the fluid and solid in river. The research into the motion characteristics, transport laws as well as the action mechanism of influencing factors can help to not only complement the fundamental theories in river dynamics, and but also solve the urgent requirements from the practical engineering sediment. A series of flume experiments was carried out using the techniques of image recognition and instant monitoring for bed load. By introducing the comprehensive flow intensity ψb which refleets the thickness ratio of the bed η, properties of the viscous sublayer, the characteristic Froude number Frg, the transport characteristics of the non-uniform bed load with a bimodal distribution were investigated under several conditions such as different flow intensities and various compositions of bed material, with the effect of particle non-uniformity on transport rate of bed load being especially considered. By means of key factor identification and dimensional analysis, the transport mode of the non-uniform bimodal bed load was proposed. A formula for calculating the transport intensity of bed load was developed, which is expressed as a dimensionless function of the transport intensity φ＇ and comprehensive flow intensity Ψbased on characteristic factors near the bed. An analysis of the transport mechanism of the bimodal bed load indicates that the ratio of coarse to fine particles in the composition properties of the non-uniform sediment is an important parameter affecting the value φ. It is found that the collapsing effect of fine particles on coarse particles has an important influence on the movement of coarse particles, and therefore, the transport rates of bimodal bed load present a hump curve with the variation in the degrees of particle non-uniformity, wit the corresponding ηc of about 3：7 for the peak rate.

关 键 词：颗粒非均匀度 综合水流强度 特征弗劳德数 粘性底层 量纲一输沙率 

分 类 号：TV147[水利工程—水力学及河流动力学]