定期冲洗式沉沙池泥沙沉降特性分析

Analysis on Settlement Characteristics of Sediment in Desilting Basin with Periodic Flushing

以黄河东城提水工程首部的定期冲洗式沉沙池为研究对象,应用一维超饱和输沙法计算了泥沙的沉降历时,分析了泥沙恢复饱和系数、极限吸出高度、出池含沙量等泥沙沉降特性。结果表明:①泥沙恢复饱和系数随泥沙粒径的增大呈指数递减趋势,工作段上游泥沙恢复饱和系数随沉降历时呈指数递减趋势,工作段下游恢复饱和系数随沉降历时呈线性减小趋势;②随着沉沙池的运行,出池泥沙粒径逐渐变大,淤积泥沙粒径则逐渐变小;③在沉沙池运行期内,溢流堰极限吸出高度随沉降历时呈线性递减趋势;④溢流堰前分组含沙量参考点的相对水深均小于0.5;⑤在0～0.500 mm泥沙粒径范围内,出池平均含沙量参考点的相对水深与泥沙粒径呈对数递增。

By taking a desilting basin with periodic flushing in the header of Dongcheng Lifting Project of the Yellow River as the research object,using one dimension extra-saturation sediment discharge method,the settling time of sediment was calculated and the settlement characteristics of sediment such as the sediment recovery saturation coefficient,the limiting height of aspiration and the out flow sediment content were analyzed.The results show that： 1） as the sediment grain size increased the sediment recovery saturation coefficient shows exponentially decreasing trend,the sediment recovery saturation coefficient on upstream of working section shows exponentially decreasing trend with the settling time,and on downstream of working section shows linearly decreasing trend with the settling time;2） with the operation of desilting basin the out flow sediment grain size is gradually coarser and the deposited sediment grain size is gradually finer;3） during operation period of desilting basin,the limiting height of aspiration of overflow weir shows linearly decreasing trend with the settling time;4） the relative depth on reference point of graded sediment concentration in front of overflow weir is less than 0.5 m;5） in sediment grain size range of 0-0.500 mm,the relative depth and the sediment size on reference point of the average out flow sediment content shows logarithmic increase distribution.