Study On Flow Characteristics At The Confluence Of The Beiyun River And The Liangshui River And The General Layout Of The Yulinzhuang Sluice

The Yulinzhuang Sluice is an important flood control structure on the Beiyun River in Beijing.After 40 years of operation,it is damaged seriously,and it was identified as the fourth type of dangerous sluice and recommended to be reconstructed.The sluice is next to the confluence of the Beiyun River and the Liangshui River,and consists of two sluices and a central island.The flow conditions are very complicated.Therefore,study on the flow-sediment movement characteristics of the confluence and the different layout schemes is very important to the engineering design of the reconstruction and the safe operation of the new sluice.By a two-dimensional mathematical model and a fixed bed model test,the Yulinzhuang Sluice of current condition and different reconstruction schemes were simulated respectively.The analyses were conducted on the split ratio of flow,water level,flow velocity and flow regime of different peak flow,based on what,the advantages and disadvantages of different schemes were compared and a reasonable layout scheme of the new sluice was proposed.In addition,the riverbed evolution near the sluice was simulated under different flow conditions by a movable bed model test,and the impact on the sluice was analyzed.Through research and analysis,draw the following conclusions:First,the results obtained by the two methods are basically consistent.Second,the original location of the sluice and the northern end of the island are too close to the confluence,and the width of the west sluice is not equal to that of the east one.They cause the problems including the unreasonable split ratio of flow,the turbulent flow and the sediment deposition near the island under different flow conditions.Third,it is a recommended reconstruction scheme of sluice that the new location of sluice where is 50 meters downstream of the original location,and the same width of the new west and east sluice,and the new central island which is removed 60 meters from the northern end and extended 30 meters from the southern end of the old island.Comparing with the original and other reconstruction schemes,the recommended scheme can make the flow confluence fuller in front of the sluice,and reduce the water level of the sluice,and make the flow regime more favorable,and make the split ratio of flow more reasonable,and make the operation of the sluice more convenience.Fourth,the place is located 500 meters downstream of the sluice,where the width of the main groove is narrowed,and both sides of beaches is highly,and continuous meandering river is located in the lower reaches.It raises the sluice downstream water level.The main channel excavation of this paragraph and reconstruction of sluice should be implemented simultaneously in order to avoid affecting the flow capacity of the sluice and flood capacity of the river.Fifth,flow regime at the confluence is complex.When the sluice is at the daily use,the water depth increases and the flow rate of water decreases in front of the gate,so the sediment deposited here.It must be paid attention to the operation of the gate and dredging timely.