“圆中环”沉沙排沙池浑水沉沙特性

Turbid water desilting characteristics of circular-ring desilting and sediment ejection basin

"圆中环"沉沙排沙池是一种新型二级泥沙处理设施,以新疆呼图壁阿苇滩"圆中环"为原型,通过物理模型试验研究其浑水沉沙分布规律以及沉沙排沙效果。研究表明:"圆中环"的含沙量、沉沙范围和沉沙粒径在环向呈不均匀分布,135°~225°范围分布较大。但含沙量及沉沙粒径在径向与半径成反比,在距离圆心1/2半径处以内含沙量沿垂向与水深成反比,垂向分布不均匀,沉沙颗粒较粗,其余范围含沙量垂向分布较均匀,沉沙颗粒较细;在设计工况条件下,"圆中环"截沙率为90.9%,>1 mm粒径范围截沙率为100%。试验证明:"圆中环"存在泥沙分选现象,水沙分离依靠重力沉降,溢流堰长是沉沙效率高的重要原因。"圆中环"沉沙粒径范围大,截沙率高,排沙耗水率较小,并能利用水力作用自动排出沉沙。研究结果可为"圆中环"优化结构形式及设计应用提供参考。

Circular rings desilting and sediment ejection basin are new secondary sediment treatment facilities, which was first applied in Xinjiang Hutubi Aweitan canal head. Agricultural water was solved emphatically in the Aweitan irrigated area. ＂Circular rings＂ have worked satisfactorily since 2006. Taking Xinjiang Hutubi Aweitan ＂circular rings＂ as a prototype, the experimental model on turbid water movement characteristics has been studied. Sediment concentration distribution was tested by the computer aided sediment meter of CYS-III-Type. The sediment particle diameter was measured in the outflow channel and different radius range of ＂circular rings. Meanwhile, the desilting rate and water consumption were calculated, as well as the maximum particle diameter in the outflow channel. The research showed that the distribution of sediment concentration, desilting range, desilting diameter and desilting production are non-uniform in the ring direction of ＂circular rings＂. However, sediment concentration distribution and particle diameter size are inversely proportional to the radius in the radial direction. Sediment concentration is inversely proportional to water depth in the vertical direction, vertically non-uniform within 1/2 radius. Meanwhile, sediment grain size is crude. In other ranges, vertical distribution is more uniform and sediment grain size is smaller. Distribution of sediment concentration, desilting diameter and desilting production are larger in the range of 135^-225~ in ＂circular rings＂. Under the design discharge and sediment concentration conditions, the desilting rate is 90.9 percent of ＂Circular rings＂. The maximum particle-size is 0.935mm in the outflow channel. The desilting rate for grain which diameter is more than 1 mm is 100 percent, while the water consumption is only 6.6 percent. When considering the annual flow and sediment concentration conditions, the water consumption well is reduced, but the amplitude reduction should be further studied. Discharging of sediment is achieved by means of the water flow energy, steeper inverted cone bottom slope, self-weight sediment, as well as high-speed circulation. The experiment proved that the model test results are in accordance with the prototype in ＂circular rings＂. The sorting phenomenon of the sediment particle was obviously existed. Separating water and sediment was decided by gravity sedimentation, One of the most important reasons is that the high desilting efficiency obtained by the long overflow weir. It has a high desilting rate, desilting particle range and low water consumption, especially taking advantage of the draining bed sediment of coarse grain. Meanwhile, automatically discharging of the sediment is achieved by an intermittent way. Therefore, promoting the use of ＂circular rings＂ has important significance for improving the agricultural water-saving irrigation efficiency and sufficiently utilizing water resources.