引黄灌渠泥沙迁移特性与渠道挟沙力模型试验研究

Experimental Study on Sediment Transport Characteristics and Channel Sediment Carrying Capacity Model of Yellow River Irrigation Canal

【目的】探索灌渠泥沙迁移特性及泥沙级配的沿程变化规律,找出减少渠道泥沙淤积的方法,保障灌区正常运行。【方法】通过对尊村灌区典型干渠高含沙水流实时监测采样,分析了悬移质泥沙沿程含沙量变化及级配特征,并根据实测数据带入4个典型挟沙力公式,筛选出适合尊村灌区的挟沙力公式,进一步改进得到尊村灌区渠道挟沙力计算公式.同时,通过一干渠改造段实测数据,推求出一干渠冲淤平衡比降计算公式。【结果】不同粒径泥沙的输移特性不同,总干渠悬移质含沙量随来水含沙量的增加而增加,渠道淤积主要与粉粒和砂粒量有关,其中砂粒对来水含沙量的变化表现得最为敏感,而黏粒更多的被水流带走,渠道由非平衡输沙经冲刷、淤积达到冲淤平衡输沙的过程比较缓慢。同时沉沙池能有效地减小引水中砂粒量。二干渠末清淤修缮段依旧存在泥沙淤积问题,一干渠剩余未改造部分,在条件允许的情况下,建议增大比降。【结论】含沙量在2 kg/m^3内时,一级站来水量在8 m^3/s左右,渠道基本实现冲淤平衡。

【Objective】The characteristics of sediment transport and the variation of sediment gradation along the way can be explored, the way to reduce the sediment deposition of the channel can be found, and the normal operation of the irrigation area can be guaranteed.【Method】Based on the real-time monitoring and sampling of high sediment concentration flow in typical main canal of Zun Village irrigation district, the variation and gradation characteristics of suspended sediment along the process were analyzed, and four typical sediment carrying capacity formulas are brought into with regards to the measured data, and the formula of sediment carrying capacity suitable for Zun Village irrigation area was selected, which further formulated the calculation formula of channel sediment carrying capacity in Zun Village irrigation area. At the same time, based on the measured data of the reconstruction section of a main canal, the formula for calculating the balance gradient of scouring and silting in a main canal was derived.【Result】The sediment transport characteristics of different particle sizes were different.The sediment concentration of suspended matter in the main canal increases with the increase of incoming water sediment content, and the channel siltation was mainly related to the content of silt and sand particles, in which sand particles were the most sensitive to the change of sediment concentration in incoming water, and more clay particles were taken away by water flow. The channel was scoured by non-equilibrium sediment transport, therefore, the process of silting to scouring and silting equilibrium sediment transport was relatively slow. Meanwhile,the sedimentation tank could effectively reduce the sand content in the diversion water. There was still the problem of sediment deposition in the end clearance and repair section of the second main canal, that was, the remaining unmodified part of main canal. If the conditions permit, it was suggested to increase the gradient.【Conclusion】When the sediment concentration is within 2 kg/m^3, the incoming water quantity of the first grade station is about 8 m^3/s, and the channel basically realizes the balance of scouring and silting.