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研究了冲积河流中显著河床变形对水流运动特性所产生的影响。根据双曲系统特征理论及奇异摄动理论,采用了渐进匹配展开方法,推导得到了一维全沙数学模型所构成的4阶拟线性双曲系统的4簇特征值。这4簇特征值表征了双曲波的传播速度。结果表明:这4簇特征值耦合了水流运动、泥沙输运及河床变形之间的相互作用。水流中扰动的传播特性随着不同程度河床变形的影响而发生变化,且扰动程度越大,这种影响也越显著。因此,当河床冲淤较为显著时,考虑河床冲淤对水流运动产生的影响是必要的。
The effect of significant river bed deformation on the flow characteristics in alluvial rivers was studied. According to the theory of hyperbolic system and singular perturbation theory, the method of incremental matching expansion is used to derive the 4-cluster eigenvalues of a 4-order quasilinear hyperbolic system composed of one-dimensional all-sand mathematical model. The four eigenvalues characterize the propagation speed of hyperbolic waves. The results show that the eigenvalues of these four clusters are the result of the interaction between water flow, sediment transport and riverbed deformation. The propagation characteristics of disturbance in water flow change with the influence of riverbed deformation in different degrees. The greater the degree of disturbance is, the more obvious this effect is. Therefore, when the ebb and flow of the riverbed is more significant, it is necessary to consider the influence of riverbed scouring and silting on the water flow.