CAJ | 학술논문

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Fr b , 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.
채용도상식별여추이질동태감측기술, 개전기우쌍봉형비균균추이질적계렬수조시험. 통과인입반영상면조조도、 점성저층특성여과립비균균도η(조세비)적종합수류강도함수Ψb、 특정불로덕수Fr b , 계통연구료불동수류강도여상사조성조건하적추이질수이특성이급과립비균균도대수사솔적영향. 통과대관건인자적변식여량강분석, 제출료쌍봉형비균균추이질수이모식, 건립료기우근벽특정인자적수류강도Ψb여비균균추이질수이강도Φ′적함수관계. 대쌍봉형저사수이궤리적분석표명, 비균균사적조성특정사득η성위영향Φ′적중요삼량; 정시세립대조립적해호작용대조사운동산생중요영향, 사추이질수이솔여과립비균균도간정현타봉관계, 봉치대응적조세비ηc약위3:7.
The non-uniform bed load transport is a complicated coherent physical process of the fluid and solid in riv-er. 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 require-ments 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 re-flects the thickness ratio of the bed η, properties of the viscous sublayer, the characteristic Froude number Frb, the transport characteristics of the non-uniform bed load with a bimodal distribution were investigated under several condi-tions such as different flow intensities and various compositions of bed material, with the effect of particle non-uniform-ity on transport rate of bed load being especially considered. By means of key factor identification and dimensional a-nalysis, 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 intensityΨb based 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 correspond-ing ηc of about 3:7 for the peak rate.