若尔盖泥炭型弯曲河流的崩岸机理研究

发布时间：2018-01-31 13:39

本文关键词： 弯曲河流崩岸横向淘刷泥炭若尔盖盆地　出处：《工程科学与技术》2017年S1期 　论文类型：期刊论文

【摘要】：弯曲河流凹岸在近岸水流淘刷作用下发生崩岸是河湾横向迁移的直接动力。2011—2016年野外调查表明,黄河源的若尔盖盆地发育众多的弯曲河流,其河岸上部为泥炭层,下部为粉沙层,可称为泥炭型弯曲河流。通过分析泥炭型弯曲河流的河岸粉沙层淘刷过程,以及崩岸临界力矩平衡条件,从机理上研究泥炭型弯曲河流的横向淘刷速率与崩岸机制。泥炭型弯道的崩岸分为粉沙层淘刷与泥炭层崩塌这两个过程,并将河岸粉沙层的淘刷简化为3个阶段:1)凹岸的弯顶下游处最先受到水流的淘刷;2)开始阶段以横向淘刷直至最大距离;3)逐渐转变以纵向淘刷为主。进而,建立近岸流速与淘刷距离的关系式,近岸流速随淘刷距离增加而减少,推导出粉沙层横向淘刷速率的表达式,提出确定淘刷系数的方法,推导出泥炭层拉张临界破坏的力矩平衡方程,获得了泥炭块的临界崩塌宽度表达式,其计算值与实测值较接近。
[Abstract]:The collapse of the concave bank of a curved river is a direct driving force for the lateral migration of the river bay. The field investigation in 2011-2016 shows that there are many curved rivers developed in the Zoige basin from the source of the Yellow River. The upper part of the river bank is peat layer and the lower part is silt layer, which can be called peat bend river. The lateral scouring rate and bank collapse mechanism of peat bend river are studied from the mechanism. The bank collapse of peat bend can be divided into two processes: silt scouring brush and peat bed collapse. The scouring of silt bed of riverbank is simplified as three stages: 1) the bottom of the bend top of the concave bank is first scoured by the current. 2) at the beginning stage, the transverse scouring was carried out until the maximum distance; 3) gradually changing to longitudinal scouring. Then, the relationship between the velocity and the distance of scouring is established. The velocity decreases with the increase of scouring distance, and the expression of the lateral scouring rate of silt is deduced. The method of determining scouring coefficient is put forward, the moment equilibrium equation of peat layer tensile critical failure is derived, the expression of critical collapse width of peat block is obtained, and the calculated value is close to the measured value.
【作者单位】：长沙理工大学水利工程学院;水沙科学与水灾害防治湖南省重点实验室;黄河水利科学研究院;
【基金】：水利部黄河泥沙重点实验室开放课题基金资助项目(2017005) 国家自然科学基金资助项目(91547112;91647118) 国家国际科技合作专项资助(2014DFG72010) 湖南省研究生科研创新项目资助(CX2016B390)
【分类号】：TV147
【正文快照】： 弯曲河流以优美的形态和广泛的适应性激起人们探究其发育条件、崩岸过程与演变机制。弯曲河流广泛发育于冲积平原、草原、热带雨林、极地冻土、沙漠边缘,在冰原、深海也有非冲积弯道的行踪或遗迹[1-5],野外考察表明在青藏高原也广泛发育不同尺度的弯曲河流,特别是黄河源的若尔

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