黄河下游单向缩窄典型河道泥沙冲淤特性研究

本文选择黄河下游裴峪至官庄峪典型束窄河段为研究对象,以丁坝缩窄河道方式,通过控制水流强度、缩窄水流位置、相对缩窄尺度和边界条件等四个主要因素,进行不同缩窄尺度的动床模型试验。试验结果表明：水沙运动要素变化受相对缩窄尺度、缩窄位置和边界条件影响较大;随着相对缩窄尺度的增大,在洪水位条件下主河槽冲刷量和滩地淤积量逐渐增大,主槽范围相应扩大,其高程普遍呈下降趋势,特别是缩窄断面导流堤顶端部位出现明显的局部冲刷坑,束水冲沙、增大输沙能力的效果明显;当相对缩窄尺度B1/B大于0.50时,主流线位移、断面流速和河床冲淤的相对变化速率明显增大,这些研究成果的取得将对治黄工程具有一定的指导意义。

Study on characteristics of Sediment Scouring and deposition in the single-narrowed river channel of the Lower Yellow River

The typical single-narrowed river channel from Peiyu into Guanzhuangyu in the Lower Yellow River may be selected as a modeling subject. In the manner of narrowing channel by constructing training dike or groyne, movable channel modeling tests have been carried out by controlling some important factors such as flowing intensities, placement of narrowing cross-section, relative narrowing scale and channel bed boundary conditions. It has been indicated that the changes of hydraulic and sediment factors are closely related to placement of narrowing cross-section, relative narrowing scale and channel bed boundary conditions. With increasing of the relative narrowing scale, both the sediment amount scouring in main channel and the amount depositing on flood plain are enlarged, so are the range of main channel. On the other hand, bed elevation of main channel is lowered correspondingly; especially there occur scouring large delves on the top region of training dike in the narrowed section, which results in the effects of water passage narrowing and channel bed erosion and increasing of sediment transport capacity. When the relative narrowing scale is more than 0.5, the wandering range of main water flowing, velocity and changes of scouring and deposition are evidently increased. These results play an important role in the training projects of the Yellow River.