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采用模型沙进行水槽概化试验,研究水流泥沙从山区进入平原初期的河槽形成发展过程。经过434h的试验历时,将试验段分成三部分:0～2m的上段,2～10m的中段和10～15m的下段,并重点对原始基床上淤积体形成发展规律、河道形态演变过程及河槽塑造成因三方面进行研究,得到如下认识:淤积体在上段先纵向推进,后慢慢横向展宽,最后淤积抬高形成稳定河漫滩;中段随河槽主流向下游周期摆动,两岸淤积体前缘沿流程方向以1m间距周期发展,且形成明显的滩槽;下段弯道河槽处发生凹岸撇弯和凸岸切滩现象,主流袭夺新道,使河床表面淤积体趋于同步发展;不同试验历时下的各段断面形态表明河床整体淤积抬高发展。河道形态演变过程经历:分汊河道、单一微弯河道和蜿蜒状河道三个阶段,最终形成蜿蜒状河道,并分析出各阶段的形成原因。最后从床沙因素和边界条件对河槽塑造成因进行分析。
The model sand was used to carry out the generalized experiment of the flume to study the formation and development of fluvial sediment from the mountainous area into the initial stage of the plain. After 434h test duration, the test section is divided into three sections: the upper section of 0 ~ 2m, the middle section of 2 ~ 10m and the lower section of 10 ~ 15m, and focuses on the formation and development of sediment body on the original bed, The causes of the three aspects of research, get the following understanding: silt body in the first paragraph of the vertical advance, and then slowly horizontal widening, the last siltation uplift to form a stable river floodplain; the middle section with the mainstream of the river channel to the downstream cycle swing, silt front along the flow direction 1m spacing cycle, and the formation of a clear beach trough; the lower bend at the flume bend concave bank and bankrupt phenomenon, the mainstream of the new channel hit, the river bed surface sediment tends to synchronous development; different test duration The section shape of each section indicates that the entire siltation of the riverbed has risen and developed. The evolution of the river course experiences three stages: sub-river channel, single micro-bend channel and meandering river channel, finally forming a meandering channel and analyzing the formation reason of each stage. Finally, from the bed and sand factors and boundary conditions on the shape of the river channel analysis.