一种正弦派生曲线弯道的演变试验研究

Experimental study on processes of sine-generated rivers

不同河流形态间的交替转化,伴随着河流阻力规律的变化。为研究基础河型的演化规律,在实验室条件下,通过控制初始河道弯曲度、河宽以及流量,对正弦派生曲线弯道短期演变的特征规律,如河岸线、水流动力轴线和地形变化等进行了研究。结果清晰地表明了不同工况下河道的不同发展特征,＂大水＂条件下河道容易渠道化,河岸线趋于顺直,河道宽度主要受到初始河道弯曲度及水流流量的影响。总体来看,用非黏性泥沙作为实验材料,实验河道易向着游荡型方向发展,但在一定的时间段内,存在着典型弯曲河道演变特征,且可明显地观察到床面对流量的非线性响应特征。实验结果能为天然河流的平面形态演变研究提供支持。

Flow resistance law changes with the transformation of river patterns. To understand evolution laws of fundamental channels,initial channel sinuousness,channel width and dominant discharge are controlled to simulate short-term development of sine-generated meander river in laboratory conditions. Various measurements on the bank-line,flow field,and bed topography clearly indicates that different initial river conditions lead to different development characteristics. For example,（ 1） in the ＂High Flow＂runs,initial sine-generated channels gradually become channelized on the whole（ bank-lines tend to be straight）;（ 2） the river corridor width mainly depends on the meander amplitude in the experiments,which is mainly controlled by sinuousness and water discharge;（ 3） braided rivers are generally easy to produce by non-cohesive sediment in flood plains,but there exist typical meander river processes in a certain period;（ 4） discharge influences the riverbed nonlinearly. The experiment results offer a basis for further study on the morphological evolution of largescale natural rivers.