南水北调中线输水渠道中分水口的影响

Effect of diversions in the middle route of the South-to-North Water Transfer Channel

为研究南水北调中线输水渠道中分水口流量变化对干渠的影响特征,选取天津分水口为例,采用一维Saint-Venant数学模型模拟计算该分水口各种分水状态下干渠中的水流过渡过程。采用虚拟渠道等效糙率法来模拟渠道中各类型的输水建筑物的影响。得出该分水口关闭时间超过33.6 h会导致紧邻下游端的西黑山节制闸前水位出现漫顶,分水口前水位下降速度与分水口流量变率呈线性变化关系,并给出了其拟合公式。

The effect of variations in diversion discharge on the flow processes in the middle route of the South-to-North Water Transfer Channel was simulated using the Saint Venant mathematical model. The Tianjin diversion, which is the largest one on the whole middle route, was used as an example for the simulation of the flow transitional processes in the channel under various diversion rates. The analysis used a short virtual channel with an equivalent roughness to replace the actual hydraulic structures to simulate their effect on the water surface profile in the channel. The analysis indicates that the water overflowed the channel banks in front of the Xiheishan control gate, which is located at the downstream of the diversion gate, 33.6 h after the Tianjin diversion was closed. The rate of decrease of the water surface elevation in front of the diversion varies linearly with the diversion discharge. A regression equation between the rate of decrease of the water surface elevation and the diversion discharge was developed.