弯曲河段床面分形特征及床面阻力试验研究

Experimental study of bed surface fractional characteristics and bed form resistance in meandering channels

  • 摘要: 根据概化水槽试验的结果,引入河床表面分形维数(以下简称BSD)用于河床表面形态的量化研究,并对BSD的计算方法、弯曲河道的分形特征及BSD值的大小与床面阻力的关系进行了探讨.结果表明,BSD的大小在大尺度上能够反映河段在纵向上的深泓起伏程度和横向的滩槽差,在小尺度上能反映河床表面相对的冲淤幅度,即弯曲河段床面具有明显的分形特征,同时也说明BSD可作为河床表面粗糙高度的一种量度,从而进一步研究了床面阻力与河床表面BSD的关系,研究表明床面阻力会随着河床表面BSD的增大而增大,但对于中小水流量和大水流量,床面阻力与河床表面BSD的关系可明显的分为两个区.

     

    Abstract: The riverbed morphology is quantitatively evaluated using the generalized data from flume experiments to calculate the fractal dimension of riverbed surface(hereinafter referred to as the BSD).Discussions are given on the method of BSD calculations,on the fractional characteristics in meandering channels,as well as on the relationship between the BSD and the bed form resistance.The result shows that the BSD value is able to represent the longitudinal change in talweg,transverse geometric changer in foreshores and deep channels.The scouring and silting extent or bending river bed surface,exhibits clear fractal characteristics.BSD can be used as a measure of the bed surface roughness height.The relationship between the BSD and the bed form resistance is thus established.The bed form resistance is proportional to BSD.There are two distingue regions in the different relationship between the BSD and the bed form resistance,and can be identified by flow rates.

     

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