文章摘要
新水沙条件下长江中游芦家河水道“坡陡流急”段演变机理分析
Analysis of evolution mechanism of the “steep slope and rapid flow” section in the left branch of Lujiahe waterway which is in the middle reaches of the Yangtze River on new water and sediment conditions
投稿时间:2020-06-13  修订日期:2020-10-10
DOI:
中文关键词: 三峡水库、芦家河水道、坡陡流急、演变机理、砂卵石河段
英文关键词: the  Three Gorges  Reservoir, Lujiahe  waterway, steep  slope and  rapid flow, evolution  mechanism, gravel  sand bed  reach
基金项目:国家重点研发项目
作者单位E-mail
李明 长江航道规划设计研究院 84657659@qq.com 
胡春宏 中国水利水电科学研究院流域水循环模拟与调控国家重点实验室  
周成成 长江航道规划设计研究院  
彭松柏 长江航道规划设计研究院  
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中文摘要:
      芦家河水道沙泓中段在枯水期存在著名的“坡陡流急”现象,是长江中游航道的瓶颈段。本文基于实测资料分析,系统研究了近十几年来芦家河水道沙泓的演变机理与发展趋势,结果表明,2003年三峡水库蓄水运用以来,受芦家河水道下游枯水位持续下降的影响,芦家河水道进出口落差加大,枯水比降在沙泓中段进一步集中;长达1.7km的沙泓中段表流加速段是水位控制核心区段,比降增加最为明显,并导致急流段流速持续增加,估计三峡水库蓄水运用以来7000~8000m3/s流量区间的最大表面流速增加了约1m/s;河床的强抗冲性是维持沙泓中段“坡陡流急”现象的前提条件,急流区河床组成以宽级配卵石为主,近年来急流区河床在持续冲刷下切过程中,存在卵石短程输移搬运的现象;主要冲刷区河床抗冲性有所减弱,可能存在抗冲粗化层破坏的情况,若芦家河水道出口枯水位进一步下降,急流区存在进一步冲刷下切的趋势。本研究试图为芦家河水道乃至整个砂卵石河段的航道维护与治理提供技术支撑。
英文摘要:
      The phenomenon of steep slope and rapid flow in the dry season, observed in the middle section of the left branch of Lujiahe waterway which is channel bottleneck in the middle reaches of the Yangtze River, is very famous. Based on the analysis of the measured data, this paper systematically studies the evolution mechanism and development trend of the left branch in Lujiahe waterway in the past ten years. In Lujiahe waterway, because the continuous lowering of downstream water level, the height of water level drop from inlet to outlet has increased, and the water surface slope has been further concentrated in the middle section of the left branch. The velocity acceleration section with the length of 1.7km in the left branch is the core section of water level control, which has the most obvious increase of water surface slope, and it is estimated that the maximum surface velocity in the 7000~8000m3/s flow section has increased by about 1m/s since the Three Gorges Reservoir operation. The strong anti-scouring ability of the riverbed is the precondition for maintaining the phenomenon of "steep slope and rapid flow" in the middle section of the left branch. This paper points out that the riverbed in the jet section is mainly composed of gravels and pebbles with a wide size distribution, which are continuously scoured and cut down due to the aggravation of rapid flow, with a phenomenon of short-range transport of gravels and pebbles. This paper also points out that the anti-scouring ability of the riverbed in the main scouring area has been weakened, which may lead to the damage of the armoring layer, and there is a trend of further scouring in the jet section due to further more lowering of downstream water level. This study attempts to provide technical support for the waterway maintenance and regulation of Lujiahe waterway and even the whole gravel sand bed reach downstream of the Three Gorges Reservoir.
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