黄河下游高含沙水流基本特性与输沙能力

采用理论研究和实测资料分析方法对黄河下游高含沙水流的基本特性进行了系统分析,得出黄河下游高含沙水流多属于两相非均质流,与一般含沙水流具有相同的运动规律的结论。采用达西阻力公式形式,给出了适用于黄河下游高含沙水流的悬移运动阻力坡降及推移运动阻力坡降计算方法。黄河下游高含沙水流经常处于不平衡输沙状态,这种不平衡输沙条件下的河段排沙比大小不能反映平衡输沙条件下的河段输沙能力。因此,探讨了河段纵坡J、横断面参数M及泥沙粗细组成对输沙能力的影响,给出了以河道形态参数表达的河道输沙能力关系。分别以花园口河段和艾山河段为代表分析了黄河下游上、下河段输沙能力大小的沿程变化,发现相同流量下,上段河道输沙能力为下段河道的1.3~1.4倍。本文成果对研究黄河下游高含沙洪水处理对策及水库调水调沙运用的效果具有一定理论意义和实际价值。

Basic characteristics and sediment transport capacity of hyper concentrated flow of Lower Yellow River

A systematic analysis on the basic characteristics of the hyper concentrated flow of the Lower Yellow River is made herein with theoretical study and data analysis. It is considered that the most part of the hyper concentrated flow in the Lower Yellow River belongs to the two-phase heterogeneous flow with the movement law similar to the normal sediment-laden flow. Based on the Darcy-weisbach resistance formula，the methods suitable for calculating the resistance gradients of both the suspended sediment movement and the bed-load movement of the hyper concentrated flow in the Lower Yellow River are proposed. As the hyper concentrated flow of the Lower Yellow River is often in a state of non-equilibrium sediment transport，the sediment value of the delivery ratio under the condition of the non-equilibrium sediment transport cannot reflect the sediment transport capacity therein under the condition of equilibrium sediment transport. Therefore，the impacts from the stream gradient J，cross-sectional shape parameter M and the composition of different grain sizes on the sediment transport capacity are studied，and then a sediment transport capacity formula expressed in terms of the channel cross-section morphological parameters is put forward. Moreover，by taking Huayuankou and Aishan reaches as the study cases，the change of the sediment transport capacity along the river from the upper to the lower reaches of the Lower Yellow River is analyzed and it is found out that the sediment transport capacity of the upper reach is 1.3~1.4 times of that of the lower reach. The achievement obtained herein has a certain theoretical significance and practical value for study on the countermeasures for deal with the hyper concentrated flood of the Lower Yellow River and the effect of water and sediment regulation by reservoir.