分汊河段江心洲尾斜流改善的水动力数值模拟

山区河流分汊河段江心洲尾因水流汇合产生斜流,从而出现碍航问题。为揭示江心洲尾斜流对航行安全的影响,在已有的沅水大洑潭航电枢纽物理和船舶模型试验基础上,采用MIKE 21分析航道治理工程前后汇流区的水动力特征和工程改善效果。结果表明:枯水期因右汊来流流速较大且与航线间存在夹角,导致汇流区航线横流超标;在洲尾布置平行于航线的顺坝或导流墩,虽然能有效减小横流影响,但航线横流分布范围增大,流速大小仍超标。结合调整航线、疏浚航道浅区和偏转顺坝与导流墩整体布置角度等多种工程措施,可保证洲尾后航行水流指标基本满足规范要求。

Hydrodynamic numerical simulation of weakening oblique flow at mid-channel bar tail in anabranching channel

Owing to the flow confluence at the mid-channel bar tail in the anabranching channel of mountain river,the oblique flow may cause the obstacle to navigation.In order to reveal the influence of the oblique flow on the safety of navigation,the MIKE 21 hydrodynamic model is used to analyze the hydrodynamic characteristics and engineering improvement effects of the confluence area before and after the channel regulation project based on the existing physical and ship model experiments of the Dafutan navigation and power hub in Yuanshui River,a tributary of the middle Yangtze River in China. The results show that during the dry season,the oblique flow of the navigation in the confluence area exceeds the standard due to the high flow velocity in the right channel and the angle within the route.The longitudinal dike or spur dam constructed at the bar tail can reduce the impact of the oblique flow. Nonetheless,given that a longitudinal dike or spur dam parallel to the route is arranged at the bar tail,the magnitude of the oblique flow and back flow of the route increases the range of oblique flow distribution and is still beyond the standard value.Combining various engineering measures such as adjusting the shipping route,dredging the shallow area of channel,deflecting the longitudinal dike,and the overall arrangement angle of the spur pier can ensure that navigation flow at the bar tail meets the requirements of the norm.