水利枢纽下游河床冲刷与再造过程研究进展

在水利枢纽尤其是水库的拦蓄与调节作用下,下游河道的来水来沙条件显著变化,将导致下游河道不平衡输沙,引起河床冲刷与再造。水利枢纽下游河道的河床冲刷与再造过程,兼具床沙冲刷—粗化—交换—悬移质恢复等多过程耦合的微观水沙运动特性,以及泥沙冲淤—床面形态变化—纵比降改变—河型河势调整等多尺度复杂响应的宏观形态变化。国内外相关研究主要通过实测资料分析、理论研究、实体模型试验和数值模拟等手段,从微观机理和宏观规律2个主要方面开展。归纳和总结了国内外水利枢纽下游河床冲刷与再造过程研究成果,对河床冲刷与再造实体模型试验和数值模拟中的模型沙选择、泥沙恢复饱和系数等关键技术问题的研究进展进行了分析,并指出了需要进一步研究的重点和亟待解决的科技难题。

Research Progress of River Bed Scouring and Remaking Process in the Reaches Downstream of Water Conservancy Projects

Under the action of impoundment and regulation of large water conservancy projects, especially reservoirs, the incoming flow and sediment conditions of the downstream channel change remarkably, which will lead to unbalanced sediment transport in the channel, and induce scouring and remaking of the riverbed. The riverbed scour and remaking process in the downstream channel of water conservancy project is characterized by the coupling of multiple processes (inclusive of sediment scour, coarsening, exchange and suspended sediment recovery) and the macroscopic morphological changes of multi-scale complex responses (such as sediment scouring and silting, bed surface morphological changes, longitudinal slope changes, as well as river pattern and river regime adjustment). The related researches in China and abroad are mainly carried out from two aspects, namely, microscopic mechanism and macroscopic law, by means of field measurement data analysis, theoretical research, physical model test and numerical simulation. In this paper the research results of river bed scour and remaking process in the downstream of water conservancy projects in China and abroad are summarized; the research progress of key technologies in physical model test and numerical simulation of river bed scour and remaking are expounded; and the key points for further research and the scientific and technological problems to be solved are presented.