| The channel conditions were gradually improved after the 3.5m depth channel regulation project was carried out in the Chaotianmen to Fuling section of the upper reaches of the Yangtze River.However,large-scale vertical vortex still exists in the Fupingbei of Guangyangba reach for a long time,which seriously threatens the navigation safety of upstream and downstream vessels.Based on the actual topography and flow conditions of Guangyangba reach,this paper studies the evolution characteristics and control measures of large-scale vertical vortex in Fupingbei reach through physical model experiments and theoretical analysis methods,elaborates its formation mechanism and movement process,and weakes its influence through engineering measures.The main results of this paper are as follows:(1)The flow field observation algorithm based on H-S optical flow method was proposed.Combined with the physical model,the surface flow field morphology in the formation and evolution of vertical vortex at the section of Fupingbei in Guangyangba was observed.By comparing and analyzing the observation results of particle image velocimetry method and optical flow method on the surface flow field of vertical vortex,the optical flow method has better integrity and followability in the observation of large-scalevertical vortex compared with the traditional PIV technology.Therefore,this paper chooses optical flow method as the observation method of vertical vortex.(2)The formation mechanism of vertical vortex is clarified.In this paper,the flow field observation algorithm based on optical flow method is used to observe the instantaneous surface flow field in the formation stage of vertical vortex.The main characteristic parameters such as the position of the formation point of the vertical vortex,the water depth,the initial radius,the formation frequency and so on were studied with the flow rate.Based on the analysis of the topographic characteristics of the reach and the variation trend of the flow conditions along the reach,the main factors affecting the formation of the vertical vortex are put forward: the large flow velocity difference between the left and right sides,the large topographic gradient at the end of the stone beam along the reach,and the suitable water depth along the reach for the survival of the vortex.(3)The evolution process of vertical vortex is analyzed.By observing the instantaneous surface flow field distribution of the same vertical vortex in each period of its movement,the velocity distribution and the change process of water flow pattern on the left and right channels along the river were monitored,and the variation laws of characteristic parameters such as the path,survival time,scale and intensity of the vertical vortex with the movement process were analyzed.The evolution characteristics of vertical vortex are summarized.(4)The treatment measures to weaken the strength of vertical vortex are given.According to the main factors affecting the formation of vertical vortex,two control ideas of blasting reef and changing the shape of deep pool are put forward.Through studying the variation law of vertical vortex scale and intensity under different working conditions,the improvement degree of vertical vortex under different schemes is analyzed.The recommended scheme combining underwater reef blasting with deep pool lifting with 10 m is proposed,which completely eliminates the influence of vertical vortex in Fupingbei reach.The results can provide reference for the management of similar beach insurance. |
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