山溪卵石性河床流速分布规律试验研究

Experimental Research on Velocity Distribution Law of Mountain Stream Pebble Bed

山溪河流具有流速大、水深小、流态多变的特点,其河流河道多为卵砾石结构,为分析其河床流速分布规律,利用变坡玻璃水槽对卵石性河道进行了模拟试验,在保证恒定均匀流的条件下,改变宽深比,分析水流垂线流速分布规律并最终得出其表达式;探讨了水槽粗糙系数的影响因素及其变化规律。结果表明,当坡度在一定范围内(1/200<i<1/60)、水深较浅时,卵石性河床水流流速呈对数分布,但有其适用局限性;河道糙率随水深增大而减小,其流速和糙率的变化规律可为泥沙输移规律提供理论参考。

Mountain river has characteristics of high velocity,small river depth and changeable flow pattern,which is mostly gravel structure of the river channel.To analyze the velocity distribution of the riverbed,a series of experiments about pebble channel were conducted in a glass flume with adjustable slope.Under the condition of constant uniform flow and different breadth depth ratio,the distribution of vertical velocity of water was analyzed and the expression of the velocity distribution was obtained.At the mean time,influencing factors and variation law of the roughness of flume were discussed.The results show that when the slope is within a certain range（1/200i1/60）and the water depth is shallow,the flow velocity of the pebble riverbed is logarithmically distributed,which has its applicable limitations;the river roughness decreases with the increase of water depth.The variation of flow velocity and roughness can provide theoretical reference for the law of sediment transport.