摘要
河床粗化过程中,床面表层泥沙颗粒的相对位置随机变化,对于非均匀沙输移特性的研究较为困难,已有研究大多采用试验方法.为了定量描述河床粗化过程中泥沙颗粒间的相对位置关系,首先提出非均匀沙暴露角θi的概念,并建立暴露角θi与隐蔽度Δi及非均匀系数σg的关系式,得到了非均匀沙起动过程中的力臂计算公式;在此基础上,运用概率分析法,从理论上推导出河床粗化过程中床面泥沙的可悬及可滚概率,进而得到了基于起动概率的清水冲刷后河床粗化层级配的计算方法,该方法也能用于预测泥沙输移过程中的推移质级配;最后采用搜集到的宽级配非均匀沙清水冲刷水槽试验资料对本文提出的计算方法进行验证,验证结果表明公式计算值与实测资料符合较好.因此本文提出的河床粗化层级配计算方法,可为天然河流中沙质河床或卵石夹沙河床粗化机理研究提供依据.
Because the relative position of surface sediment within the bed armoring layer changes randomly,and it is very difficult to investigate the characteristics of graded sediment transport.Existing studies on riverbed armoring layer were based on laboratory experiments.Therefore,the exposure angleθiof non-uniform sediment is proposed to quantitatively describe the relative position between sediment particles in riverbed surface,and a relation between exposure angleθi,hiding degreeΔiand non-uniformity coefficientσgis developed.On this basis,using the probability method of sediment initiation,the suspension and rolling probabilities of non-uniform sediment on the bed surface are derived theoretically,and then a formula is proposed for the grain size distribution of river bed-armoring layer under clear water scouring.Moreover,the probability method developed in this study can be used to predict the bed-load gradation in riverbed armoring process.The probability method was verified by the measured data of bedarmoring layers owing to clear water scouring.Through validation with experimental data in the literature,the formula developed in this study is proved to be reasonable and has a higher calculation accuracy,and it contributes to the full understanding of sediment transport on both sand-bed and gravel-sand bed channels.
作者
李林林
夏军强
周美蓉
邓珊珊
LI Linlin;XIA Junqiang;ZHOU Meirong;DENG Shanshan(State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan 430072,China)
出处
《应用基础与工程科学学报》
EI
CSCD
北大核心
2020年第6期1281-1293,共13页
Journal of Basic Science and Engineering
基金
国家重点研发计划项目(2016YFC0402303)
国家自然科学基金项目(51725902,51579186)
关键词
清水冲刷
起动概率
粗化层级配
隐暴作用
非均匀沙
泥沙输移
clear-water scouring
probability of sediment initiation
grain size distribution of river bed armoring
the hiding-exposure effects
non-uniform bed material
sediment transport
