喀斯特槽谷区岩石与坡面夹角对坡面集中流水力学特性的影响
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国家重点研发计划课题(2016YFC0502303)和国家自然科学基金项目(41771312)资助


Hydraulic Characteristics of Concentrated Flow Relative to Angle between Rock and Slope in the Karst Trough Valley Area
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National Key Research Developmental Program of China (No.2016YFC0502303) and National Natural Science Foundation of China (No.41771312)

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    摘要:

    喀斯特槽谷区地表出露的岩石与坡面形成不同夹角,塑造了复杂的微地貌,显著改变坡面集中水流路径,使得水流特性发生重大变化。目前,不同岩石与坡面夹角下集中流水力学特性的变化特征还不清楚。通过室内放水冲刷模拟试验,研究了3个坡度(10°、15°和20°)、3个冲刷流量(5、7.5、10 L·min-1)和6个岩石与坡面夹角(30°、60°、90°、120°、150°和180°(0°))组合条件下喀斯特槽谷区地表集中流的水力学特性。结果表明:集中水流雷诺数(Re)随冲刷历时变化趋势较复杂,试验条件下,Re随流量的增大而增大,随坡度变化规律不明显,变化范围为517~3 343。Darcy-Weisbach阻力系数(f)随冲刷历时表现出增大的变化趋势,其随坡度增大而增大,随流量增大而减小,变化范围为0.62~5.70。Re和岩石与坡面夹角关系均不显著,f和岩石与坡面夹角间的关系在各流量和坡度组合下表现不同。fRe之间的耦合关系受岩石与坡面夹角的显著影响,当岩层与坡面夹角小于90°时,f-Re关系用对数方程描述比较好;夹角大于等于90°时,则用幂函数方程描述更好。试验条件下,当Re<1 791时,fRe关系不显著;当Re>1 791时,fRe则呈显著正相关。本研究可为喀斯特槽谷区土壤侵蚀预报模型的建立提供依据。

    Abstract:

    [Objective] Outcrops of rock in the Karst Trough Valley Area often form angles with slopes, thus making micro landforms complicated and altering significantly paths of concentrated flows, and consequently bringing about great changes in characteristics of the flows. So, it’s important to study hydraulic characteristics of the concentrated flows relative to angle between rock strata and slope. [Method] To that end, a flume experiment, designed to have combinations of three slope gradients (10°, 15° and 20°), three flow rates (5, 7.5 and 10 L·min-1) and six angles between the rock and slope (30°, 60°, 90°, 120°, 150° and 180°(0°)), was carried out. [Result] Results show that hydraulic characteristics of a concentrated flow varied significantly with the angle between the rock and slope. Reynolds number (Re) of the concentrated flow changed with duration of the scouring in a complicated trend, but exhibited a significant trend of increasing with rising flow rate, and an insignificant one of changing with slope gradient. And it varied in the range of 517~3 343 in the experiment. Darcy-Weisbach friction coefficient (f) of the concentrated flow increased with rising slope gradient and with scouring going on, but decreased with rising flow rate. And it varied in the range of 0.62~5.70 in the experiment. The relationship of Re with angles between rock and the slope was not significant, but that of f varied with combinations of slope gradient and flow rate. The coupling relationship between f and Re was influenced significantly by the angle between the rock and the slope. It could be better described with a logarithmic equation when the angle between the rock and the slope was narrower than 90°, and with a power function equation when the angle between the rock and the slope was wider than or equal to 90°. In the experiment, when Re<1 791, the relationship between f and Re was not apparent, but when Re>1 791, it was significantly positive.[Conclusion] To sum up, f and Re and their relationship vary with the angle between the rock and the slope. The findings in this experiment may provide strong data support for establishing soil erosion prediction models in the Karst Trough Valley Area.

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曾荣昌,张玉启,何丙辉,李天阳,曾成.喀斯特槽谷区岩石与坡面夹角对坡面集中流水力学特性的影响[J].土壤学报,2021,58(5):1179-1189. DOI:10.11766/trxb202002140046 ZENG Rongchang, ZHANG Yuqi, HE Binghui, LI Tianyang, ZENG Cheng. Hydraulic Characteristics of Concentrated Flow Relative to Angle between Rock and Slope in the Karst Trough Valley Area[J]. Acta Pedologica Sinica,2021,58(5):1179-1189.

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  • 收稿日期:2020-02-14
  • 最后修改日期:2020-06-07
  • 录用日期:2020-09-04
  • 在线发布日期: 2020-12-08
  • 出版日期: 2021-09-11