山区河流河床粗化层失稳临界条件分析(摘要)

王强，聂锐华，杨克君，刘兴年

(四川大学水力学与山区河流开发保护国家重点实验室，水利水电学院，四川　成都　610065)

【摘　要】　山区河流在上游泥沙补给不足时往往会形成稳定的粗化层，当水流强度增大到一定程度时会发生粗化层打破与重建的现象，为了研究山区河流粗化河床在水流强度变化时河床失稳的临界条件，共进行了2组宽级配泥沙(粒径范围1.0～15.0mm)清水冲刷粗化层破坏试验。试验采用了推移质自动测量系统对试验破坏过程中的推移质输沙率进行测量。结果表明：当床面剪切应力大于粗化层形成时床面剪切应力的1.2倍时，推移质输沙率会出现猛增的现象，床面形成的粗化层被打破；采用梅叶-彼得输沙公式的基本形式将其他学者与本文试验数据进行回归分析，分别得到当无量纲希尔兹数与无量纲临界希尔兹数比值Θ/Θc大于或小于1.2时，清水冲刷与粗化过程中的推移质最大输沙率gbmax相对应的无量纲输沙强度G*与Θ/Θc之间的相关关系。

【关键词】　粗化层；推移质输沙率；无量纲希尔兹数；水流强度

基金项目：国家重点研发计划项目课题(2016YFC0402302)；国家自然科学基金重点项目(51539007)。

作者简介：王强(1991—　)，男，山西大同人，博士，主要从事水利学及河流动力学研究。

E-mail:scunie@163.com

Analysis on Critical Conditions of Armor Layer Instability in Mountainous River

WANG Qiang，NIE Ruihua，YANG Kejun，LIU Xingnian

(State Key Lab of Hydraulics and Mountain River Eng，College of Water Resource &Hydropower，Sichuan University，Chengdu Sichuan Province　610065)

Abstract:Armor layer always formed when the sediment supply is limited from the upstream of mountainous rivers.The armor layer will be broken up and reconstruction during the process when the flow magnitude increase to certain intensity.In order to study the critical conditions of rivers bed instability in coarsening bed,two sets of wide grading sediment(particle size range 1.0-15.0mm)experiments were investigated.The automatic mass transfer system was used to measure the sediment transport rate during the whole experiment process.The results show that when the shear stress of the bed is larger than 1.2 times of the shear stress of the bed during the formation of the roughened layer,the sediment transport rate will increase sharply and the roughened layer is broken.In this paper,the regression analysis of other scholars and the our experimental data is carried out by using the basic form of the Meyer-Peter’s sediment transport formula.When the dimensionless Shields number and the dimensionless critical Shields number are Θ/Θc greater than or less than 1.2,we can get the correlation relationship between the dimensionless sediment transport intensity G* corresponding to the maximum sediment transport rate gbmax and Θ/Θc in the process of scouring and coarsening.

Key words:Armor Layer;Bed-load Sediment Transport Rate;Shields Number;Flow Magnitude