通过最初被粘性沉积物覆盖的底部隧道进行水库冲刷的实验研究

IF 3.5 2区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES
Huan Xu, Zhixian Cao
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引用次数: 0

摘要

水库泥沙冲刷是缓解水库泥沙淤积最有效的策略之一,包括通过底部隧道向下游排放含泥沙的水流。然而,如果底部隧道的进水口最初被粘性沉积物覆盖,是否能实现冲刷,目前仍鲜为人知。在此,我们进行了水槽实验来研究水库中的粘性沉积物冲刷问题。实验证明,水库中的粘性沉积物比非粘性沉积物更难冲刷。水库中较高的水位、最初较小的覆盖层厚度以及较低的沉积物干密度都有利于发生沉积物冲刷。粘性泥沙的冲刷过程在很大程度上受到渗流的影响。在重力侵蚀和水流侵蚀的共同作用下,大坝上游冲刷孔的边缘呈棱角状和破碎状。本文评估了非粘性沉积物和粘性沉积物冲刷的临界条件。提出了适用于非粘性和粘性沉积物的经验公式,以估算紧靠底部隧道进水口上游的平衡冲刷深度。此外,还针对海底隧道中沉积物位置的时间变化提出了经验模型。目前的研究结果对河流上携带细粒粘性泥沙的水库的设计和运行具有重要指导意义,有助于提高水库效益和保持库容。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Experimental study of reservoir flushing through a bottom tunnel initially covered by cohesive sediment

Reservoir sediment flushing, one of the most effective strategies for alleviating reservoir sedimentation, involves discharging sediment-laden flows downstream through bottom tunnels. However, whether flushing can be accomplished if the intake of a bottom tunnel is initially covered by cohesive sediment remains poorly understood. Here, flume experiments were done to investigate cohesive sediment flushing in a reservoir. It is demonstrated that cohesive sediment in a reservoir is harder to flush than non-cohesive sediment. A higher water level in the reservoir, initially smaller cover layer thickness, and lower dry density of the sediment favor the occurrence of sediment flushing. The flushing process of cohesive sediment is significantly affected by seepage. Under the combined action of gravity erosion and water erosion, the scour hole upstream of the dam is characterized by angular and broken edges. The threshold conditions for flushing of non-cohesive and cohesive sediments are evaluated. Empirical formulas applicable to both non-cohesive and cohesive sediment are proposed to estimate the equilibrium scour depth immediately upstream of the bottom tunnel intake. Also, empirical models are proposed for the time variation of sediment position in the bottom tunnel. The current findings are significant for informing the design and operation of reservoirs on rivers carrying fine-grained cohesive sediment in support of reservoir benefits and capacity preservation.

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来源期刊
International Journal of Sediment Research
International Journal of Sediment Research 环境科学-环境科学
CiteScore
6.90
自引率
5.60%
发文量
88
审稿时长
74 days
期刊介绍: International Journal of Sediment Research, the Official Journal of The International Research and Training Center on Erosion and Sedimentation and The World Association for Sedimentation and Erosion Research, publishes scientific and technical papers on all aspects of erosion and sedimentation interpreted in its widest sense. The subject matter is to include not only the mechanics of sediment transport and fluvial processes, but also what is related to geography, geomorphology, soil erosion, watershed management, sedimentology, environmental and ecological impacts of sedimentation, social and economical effects of sedimentation and its assessment, etc. Special attention is paid to engineering problems related to sedimentation and erosion.
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