| 卵砾石沙波临界水流条件的水槽试验 |
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| 引用本文： | 付旭辉,杨胜发.卵砾石沙波临界水流条件的水槽试验[J].水科学进展,2013,24(3):379-385. |
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| 作者姓名： | 付旭辉 杨胜发 |
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| 作者单位： | 1.重庆交通大学国家内河航道整治工程技术研究中心,重庆 400074; |
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| 基金项目： | “十二五”国家科技支撑计划资助项目(2012BAB05B03);重庆市科委自然科学基金资助项目(CSTC 2011GGC036)~~ |
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| 摘 要： | 以往对沙波的研究多针对河流中下游、河口海岸段的细沙(粒径D<1 mm),而长江上游等卵砾石输移河段(D>2 mm)是否会出现沙波以及卵砾石沙波的临界条件,尚需开展进一步研究。通过长江上游九堆子、筲箕背等卵石滩的现场踏勘,观察到明显的天然沙波形态。采用中值粒径D50=1.8 mm和5.3 mm的天然沙和D50=4.8 mm的轻质沙进行水槽试验,成功模拟出砾石沙波。根据恒定均匀流条件下,产生沙波的比降、水位、流量等水流条件及试验沙的粒径、比重,提出卵砾石沙波的临界条件公式。结果表明,卵砾石沙波的临界条件可以用量纲起动功率w* 、R／D及比降S表达,并据此提出判别系数GDcr。当研究河段的卵砾石输移带上的水流条件满足判别系数GDcr,则可以判断能够产生沙波现象。
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| 关 键 词： | 卵砾石 沙波 泥沙输移 水槽实验 临界条件 |
| 收稿时间： | 2012-03-16 |
A flume experiment on critical flow conditions with gravel dunes |
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| FU Xuhui,YANG Shengfa.A flume experiment on critical flow conditions with gravel dunes[J].Advances in Water Science,2013,24(3):379-385. |
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| Authors: | FU Xuhui YANG Shengfa |
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| Institution: | 1.National Engineering Research Center for Inland Waterway Regulation, Chongqing Jiaotong University, Chongqing 400074, China;2.Key Laboratory of Hydraulic and Waterway Engineering of the Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China |
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| Abstract: | Gravel dunes are the typical form of bed load motion and one of the research focuses in river dynamics, which determines the bed resistance, the bed geometry and the bed load transport rate in alluvial rivers. Most previous studies focused on the fine sediment in the middle and lower reach of rivers or in estuaries and coast areas where the grain diameter is less than 1mm. Thus, further research should be done to determine whether gravel dunes (D>2 mm) exist in mountain rivers and how to estimate the critical condition. On the basis of field surveys at Jiuduizi and Shaojibei sites in the upper reach of the Yangtze River, it is apparent that the natural form of gravel dunes does exit in mountain rivers. A series flume experiments were carried out with nature sediment (D50=1.8 mm, 5.3 mm) and coal (D50=4.8 mm) and stable uniform flow conditions, to simulate the formation of gravel dunes. A formula of critical condition for gravel dunes is proposed, which is expressed in terms of the dimensionless flow power w*, R/D and the slope S according to the energy slope, the average water depth, the discharge and other parameters of the flume experiment. The discriminate coefficient of gravel dunes GDcr is also proposed to determinate whether dunes exist on gravel transport belt. The study can provide a reference for the regulation of channel activity, flood defense preparations and bed load transport predictions. |
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| Keywords: | sand and gravel dune sediment transport flume experiment critical conditions |
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