Comparison study on the conditions for incipient motion of cohesionless sediment based on the concept of equivalent grain size
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摘要: 通过将等效粒径引入非均匀沙起动条件表达式,得到了基于等效粒径的非均匀沙起动条件统一表达式,并从反映泥沙的非均匀性引起的荫蔽(暴露)作用与分选作用角度对当前有一定影响的非均匀沙起动条件的等效粒径表达式进行了对比研究。结果表明,各家公式都能够反映泥沙的非均匀性引起的荫蔽(暴露)作用,较粗泥沙颗粒的等效粒径小于其自身粒径,容易起动,较细泥沙颗粒的等效粒径大于其自身粒径,较难起动。但是不同公式之间还是有一定的差异,主要反映在细颗粒的荫蔽作用方面。不同公式区分非均匀沙颗粒间荫蔽(暴露)作用的特征粒径是不同的。韩其为、张启卫、刘兴年公式能较好的反映泥沙起动时的分选作用。对于细颗粒泥沙而言,Egiazaroff、Hayashi与秦荣昱公式在冲刷时体现由于床沙粒径不同而产生的分选作用相对较差。Abstract: A uniform expression is presented to describe the incipient motion of nonuniform sediment based on the concept of equivalent grain size.Using eight formulas,a comparison study is conducted to explore the issues of hiding and exposure and the aspects of sediment sorting due to heterogeneity.Results show that the hiding and exposure effect is well described in the modeling of nonuniform sediment transport by all eight formulas.Coarse sediment is usually underrepresented by its equivalent particle size,which can artificially ease the condition for incipient motion of coarse sediment.The opposite is true for fine sediment.However,there are still some differences among the formulas,mainly in dealing with the hiding effect of fine sediment.Different formulas use different feature sizes to simulate the hiding and exposure effect of nonuniform sediment.Among those,HAN Qi-wei,ZHANG Qi-wei and LIU Xingnian formulas can better handle the sorting function for sediment incipient motion.For fine sediment,the performance of Egiazaroff,Hayashi and QIN Rong-yu formulas is less satisfactory due to clear-water scouring.
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Key words:
- incipient motion /
- cohesionless sediment /
- equivalent grain size /
- hiding and exposure /
- sorting
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[1] LICK W,JIN L,GAILANI J.Initiation of movement of quartz particles[J].Journal of Hydraulic Engineering,2004,130(8):755-761. [2] CAO Zhi-xian,PENDER G,MENG Jian.Explicit formulation of the shields diagram for incipient motion of sediment[J].Journal of Hydraulic Engineering,2006,132(10):1097-1099. [3] DE LINARES M,BELLEUDY P.Critical shear stress of bimodal sediment in sand-gravel rivers[J].Journal of Hydraulic Engineering,2007,133(5):555-559. [4] SARMIENTO O A,FALCON M A.Critical bed shear stress for unisize sediment[J].Journal of Hydraulic Engineering,2007,132(2):172-179. [5] MARSH N A,WESTERN A W,GRAYSON R B.Comparison of methods for predicting incipient motion for sand beds[J].Journal of Hydraulic Engineering,2004,130(7):616-621. [6] 聂锐华,刘兴年,曹叔尤,等.无粘性泥沙起动条件对比研究[J].水科学进展,2004,15(5):584-587.(NIE Rui-hua,LIU Xing-nian,CAO Shu-you,et al.Comparison study on incipient motion conditions for cohesionless sediment[J].Advances in Water Science,2004,15(5):584-587.(in Chinese)) [7] BUFFINGTON J M,MONTGMERY D R.A systematic analysis of eight decades of incipient motion studies with special reference to gravel-bedded rivers[J].Water Resource Research,1997,33(8):1993-2029. [8] 褚君达.无粘性泥沙的起动条件[J].水科学进展,1993,4(1):37-43.(CHU Jun-da.Conditions of incipient motion of non-cohesive sediments[J].Advances in Water Science,1993,4(1):37-43.(in Chinese)) [9] 刘兴年.非均匀沙推移质输沙率及其粗化稳定[D].成都:成都科技大学,1986.(LIU Xing-nian.Non-uniform bed load transport rate and coarsening stabilization[D].Chengdu:Chengdu University of Technology,1986.(in Chinese)) [10] 聂锐华.非均匀沙卵石推移质输移复杂特性研究[D].四川大学博士论文,2010.(NIE Rui-hua.Study on the complicated properties of nonuniform gravel bedload transport[D].Chengdu:Sichuan University,2010.(in Chinese)) [11] 韩其为,何明民.泥沙起动规律及起动流速[M].北京:科学出版社,1999.(HAN Qi-wei,HE Ming-min.The incipinet mechanism and velocity of sediment[M].Beijing:Science Press,1999.(in Chinese)) -
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