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黄河下游发生高含沙洪水时常伴随洪峰增值的异常现象,给黄河下游的防洪安全带来了极大的影响。本文基于高含沙水流床面附近存在流凝现象并可能形成具有屈服应力的黏性底层的事实,建立了高含沙洪水分层模型和流动的波系方程,对多沙河流非漫滩洪水洪峰沿程增值现象的机理进行了研究,并给出了发生洪峰增值的临界条件。论文还应用该结果对2004年、2010年发生的黄河下游高含沙洪水增值现象进行了分析。结果表明,当洪水的Froude数大于临界Froude数时,动力波形成的逆扩散导致洪水中的扰动被扩大、集中,从而导致流动失稳,这是这两场洪水洪峰增值的根本原因。
The anomalous flood peak value often accompanied by high sediment flood in the lower Yellow River brought a great impact on the flood control and safety of the lower Yellow River. Based on the fact that there exists the phenomenon of flow and condensation near the bed surface of high sediment flow and may form a viscous bottom layer with yield stress, a stratified model of high sediment flood and wave equation of flow are established. The mechanism of flood phenomenon along flood peak is researched, and the critical conditions of flood peak value increment are given. The paper also uses this result to analyze the value-added phenomena of high sediment flood in the lower Yellow River in 2004 and 2010. The results show that when the Froude number of the flood is greater than the critical Froude number, the inverse diffusion of the dynamic wave causes the disturbance in the flood to be enlarged and concentrated, resulting in the instability of the flow, which is the fundamental reason for the flood peak value increment of the two floods.