| 引用本文: | 程建萍,梁 谦,田建良,等.输水渠道设计中糙率取值的模型分析[J].灌溉排水学报,2021,(5):114-118. |
| CHENG Jianping,LIANG Qian,TIAN Jianliang,et al.输水渠道设计中糙率取值的模型分析[J].灌溉排水学报,2021,(5):114-118. |
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| 摘要: |
| 【目的】研究在输水渠道设计中，糙率与影响设计断面各水力要素之间的关系。【方法】主要是通过水工模型试验，测定不同流量下各水力要素值，通过分析比较，总结得出影响渠道输水能力的参数取值及水力要素的相互关系。【结果】①经试验分析得知在输水渠道设计时，某一输水区段内水面曲线和流量的关系并不是线性关系。②同一底坡下，输水渠道时沿流程水流流速减小。③糙率的取值不仅取决于材料，还取决于某一流段内水流的流态。【结论】渠道某一流段内断面水深和流量的关系并不是简单的线性关系，因此，在设计中要针对不同渠道断面形状，通过模型试验结合渠道水面曲线理论计算确定；设计输水渠道的糙率值的取用，并不能单纯取用糙率取值范围的中间值，而是针对水流流态及施工水平和运行年限综合确定。当流量在(2.41~2)×10-3 m3/s时，取0.008作为计算值应用；当流量在(2~0.9)×10-3 m3/s时，取0.008 5作为计算值应用。 |
| 关键词: 过堰流量；沿程水头损失；断面平均流速；糙率 |
| DOI：10.13522/j.cnki.ggps.2020368 |
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| Experimental Study of the Roughness Parameter of Channel |
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CHENG Jianping, LIANG Qian, TIAN Jianliang, XIAO Rang, LI Xing, MA Chengxiao
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1.College of Civil Engineering, Hexi University, Zhangye 734000, China; 2.The Hexi Corridor Institute of Water Resources Protection and Utilization, Zhangye 734000, China;3. College of Water Conservancy & Building Engineering Shihezi University, Shihezi 832000, China
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| Abstract: |
| 【Background and objective】The transport capacity of a channel depends on a multitude of factors, of which channel roughness is an important one. Currently, there is a lack of study on how to choose the roughness parameter in channel design, and the purpose of this paper is to plug this gap, systematically studying the relationship between the roughness parameter and other factors. 【Method】The study was based on experiments, from which we measured the hydraulic characteristics of channels under different water flow rates. The relationship between the hydraulic characteristics and the factors that affect transport capacity of the channels were analyzed. 【Result】①The water surface curve and water flow rate in the channel are nonlinearly related. ②When the slope of the channel bed is the same, water flow velocity decreases along the channel. Thus, to keep channel function properly, its bed slope should increase and roughness decreases. ③The value of the roughness parameter depends not only on the lining materials of the channel but also on water flow in that the roughness parameter decreases in fast-flow sections while increases in slow-flow sections. We also found that the relationship between water depth and water discharge rates could become nonlinear in some sections; channel design should consider geometrical shapes of the cross-sections by either physical simulation or theoretical calculation.【Conclusion】The roughness parameter of channel depends on many factors and should be determined based on water flow pattern, how the channel was constructed, as well as its serving history. For the experiment we studied, the roughness parameter increased from 0.008 when water flow rate was (2.41×2)×10-3 m3/s to 0.0085 when the flow rate reduced to (2.41× 0.9)×10-3 m3/s. |
| Key words: weir discharge; frictional water head loss; cross-section average water velocity of cross section; roughness |
