长江中下游阻隔性河段作用机理

发布时间：2018-02-10 17:52

  本文关键词： 阻隔性河段 水流动力轴线 河道边界 长江中下游　出处：《地理学报》2017年05期 　论文类型：期刊论文

【摘要】：阻隔性河段能够阻隔上游河势调整向下游的传递,对稳定河势起到关键性作用。本文以长江中下游34个单一河段为研究对象,在系统总结长江中下游河道演变规律的基础上,归纳出阻隔性河段控制要素包括:单一微弯的河道平面形态、河段中上部无挑流节点;河相系数小于4;河道纵比降大于1.2?;凹岸黏粒含量高于9.5%;床沙中值粒径大于0.158 mm等。从Navier-Stokes方程出发,推导出河湾水流动力轴线弯曲半径的表达式,进而分析了各控制要素对水流动力轴线摆动及阻隔性河段形成的作用。阻隔性河段的判别条件为:不同流量级下水流动力轴线摆动力与河道边界条件约束力的比值始终小于1;阻隔性河段作用机理在于:即便上游河势发生调整,本河段的河道边界始终能约束主流摆动幅度,归顺上游不同河势条件下的主流平面位置,为下游河道提供了相对稳定的入流条件,从而阻隔上游河势调整向下游传递。
[Abstract]:The barrier River can adjust the upstream to the downstream river barrier transfer, to the key role of the stable regime. In this paper, the Yangtze River 34 single river as the research object, based on systematic analysis of middle and lower Yangtze River channel evolution, summed up the barrier of control elements include: single curved micro channel morphology in the upper reach, mudo flow node; river facies coefficient is less than 4; the longitudinal gradient is greater than 1.2?; clay particle content higher than 9.5% concave; sediment median particle diameter greater than 0.158 mm. Based on the Navier-Stokes equation, the deduced bend flow dynamic axis bending radius, and then analyzes the various factors on the flow control dynamic axis swing and barrier reach. Sufficient conditions for the river barrier: different discharge ratio of the flow dynamic axis shaking force and boundary conditions of channel binding was always less than 1; Is the river barrier mechanism: even if the upstream river changed, the river channel boundary always constrains the mainstream swing, the main plane position to different upstream water potential conditions, provided a stable flow condition for the downstream channel, thereby blocking the upstream to the downstream river regime.

【作者单位】： 武汉大学水资源与水电工程科学国家重点实验室;湖北省水利水电规划勘测设计院;长江勘测规划设计研究有限责任公司;工程泥沙交通运输行业重点实验室交通运输部天津水运工程科学研究所;
【基金】：国家自然科学基金重点项目(51379155) 国家科技支撑计划项目(2013BAB12B02-02) 国家重点研发计划(2016YFC0402306,2016YFC0402106) 中央级公益性科研院所基本科研业务(TKS160103)~~
【分类号】：TV147
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本文编号：1501093