摘要
河口大型围垦工程围区吞吐潮量大,河口滩势条件复杂,龙口位置选择和极值流速确定是工程设计中的关键环节。以两个典型河口大型围垦工程龙口为例,从水动力分析角度提出合理的龙口平面选址和龙口渡汛时因地制宜的结构布置。在青草沙水库工程中,龙口位置的确定充分利用围区原有深槽的过流能力,以保证库区内外及时水交换,并兼顾到围堤实施顺序与工程区整体河势环境相协调,避免口门进出水引起工程河段滩地的大冲大淤,也确保了堤基安全。龙口渡汛需要面临长时间大潮汛过流考验,龙口流速大小决定了龙口结构的保护方案和后期的合龙方案,常规使用的堰流计算方法能较为准确地计算龙口流量和断面平均流速过程,数值模型能对大型龙口流速空间分布情况进行很好的模拟,是常规计算方法的重要补充。计算结果表明口门横向上中心流速大于口门两侧流速,在纵向上底坡内外两侧顶角处水流受重力作用加强,垂向断面收缩,在涨、落急时刻分别形成大流速区,是龙口结构布置时重点抗冲保护区域,需要设置抗冲性较强、自重大且联接牢固的护面材料。此外,同一潮周期内涨急流速通常大于落急流速也是其重要水动力特点。
The closure gap which is characterized by high velocity and being hard to be closed is often the most concerned construction part of the whole reclamation project. Two engineering examples are introduced in this paper to describe hydrodynamics at the gap section in large- scale estuarine cases. Selection of reasonable location of the closure gap and its structural layout is also analyzed in view of its hydrodynamics. To minimize the negative impact on the neighboring beach for the large amount of current effuse from and into the embanked area, which may cause erosion and siltation around the project area, the gap to be closed is preferred to be positioned at a relatively deep outlet where current direction conforms to the neighbouring river flow. Two and three dimensional numerical models were implemented and the results indicate obvi- ous uneven distribution of its velocity on the gap platform, which the empirical weir theory, a familiar and predominantly used method, may not take into consideration. Furthermore, the extreme velocity at the upper comer around the two sides of the gap protection layer should be considered during the design and construction phase.
出处
《海洋工程》
CSCD
北大核心
2010年第1期110-116,共7页
The Ocean Engineering
关键词
河口
围垦工程
龙口
水动力分析
estuary
reclamation project
closure gap
hydrodynamic analysis
