黄河小北干流放淤试验“淤粗排细”效果分析

Analysis on the effect of"depositing coarse sand and discharging the fine"of warping tests in Xiaobeiganliu reach of the Yellow River

黄河小北干流连伯滩放淤试验结果显示:①在2004-2006年黄河干流来水不利的水沙条件下,通过放淤闸、弯道溢流堰、退水闸的合理布置、调度运用和淤区的合理布置,基本可以实现"淤粗排细"目标。淤区大于0.050mm的粗沙淤积量占淤积泥沙总量的39.7%,大于0.025mm的中、粗沙占淤积总量的72.2%;②淤区进口含沙量越大,泥沙粒径越粗,落淤效果越好;③淤区"淤粗"、"排细"呈明显的反比例关系,适当减小粗沙落淤率,可以显著提高细沙排出率。

According to the data of warping tests conducted on Lianbotan floodplain in Xiaobeiganliu reach of the Yellow River,the effect of＂depositing coarse sand and discharging the fine＂is analyzed.The results show that：（1）from 2004 to 2006,under the unfavorable water and sediment conditions in the main stream of the Yellow River,the test target of＂depositing coarse sand and discharging the fine＂is basically achieved through proper regulation and design to the silt-releasing sluice,overflow weir on bend,the outlet sluice and the warping area.In the warping area,the deposited sediment with size greater than 0.05mm makes up 39.7%of the total,and the size greater than 0.025mm maks up 72.2%of the total.（2）The higher sediment concentration and bigger grain size at the inlet of warping area lead a better deposition for coarse sediment. （3）In the warping area,＂depositing coarse sand＂and＂discharging the fine＂exhibits an obvious inverse proportion.Slightly reducing the deposition rate of the coarse sand in the warping area can significantly increase the returning rate of the fine sand to the main channel.