Research On Navigable Flow Conditions Of The Approach Channel Of Enlarged Capacity Of Meandering Rivers

As the demand for shipping development continues to increase,ship lock expansion and renovation projects have been launched one after another.Build a higher-level ship lock that is compatible with the upstream and downstream channel levels on the meandering rivers,affected by terrain conditions of river regime,There are often problems such as the length of the straight line required for approach channel and ship lock is insufficient,reconstruction and expansion of the ship lock project encroached on a large area of river flow,difficulty in construction of rebuilding and expanding ship lock,and interaction with the water conservancy project during the operation period of the reconstruction and expansion of the ship lock.The above-mentioned problems can be effectively solved by using high-grade ship locks that are distributed and built on the meandering rivers protruding platform,however,there is a large angle between the approach channel of the ship lock and the main flow of the river channel which is scattered on the meandering rivers and the hub.The choice of the ship lock axis is directly related to the navigable water flow conditions at the entrance area and connecting section of the upstream and downstream approach channel,the amount of approach channel excavation,land acquisition area and project investment.Therefore,the layout of the ship lock expansion project on meandering rivers needs to comprehensively compare and determine the layout of the ship lock axis from multiple aspects such as the water flow conditions of the upstream and downstream approach channel entrances and connecting sections,the amount of excavation and construction difficulty,and the space for further optimization of navigable water flow conditions.On this basis,do further optimized layout research on the flow conditions of the upstream and downstream approach channels.Find the main contradiction and take corresponding improvement measures,and finally get a better plan.This article relies on the capacity expansion project of the Chang’an Junction Ship Lock on a typical curved river.Using the research methods of physical model combined with mathematical model,multi-scheme comparison study was carried out on the selection of gate lines for the rebuilt and expanded ship locks,and the optimal layout of the upstream and downstream approach channels,and obtained a layout plan with relatively good navigable water flow conditions,relatively small impact on the upstream and downstream rivers,and more coordinated navigation capacity of the upstream and downstream rivers of the hub.The main research results of the article are as follows:(1)Analyzed the layout of ship locks on curved rivers.When there is a suitable terrace on the convex bank of a curved river,the distributed layout scheme should be chosen for the reconstruction and expansion of the lock,and the connection and transition between the lock and the upstream and downstream channels should be considered in combination with the river regime and current conditions.When necessary,engineering measures such as damming and dredging should be taken to improve the navigation conditions of the lock.(2)The evaluation conclusion of the scheme of Chang ’an Hub Lock Line Reconstruction and Extension is put forward.Adopt the method of theory analysis combined with two-dimensional mathematical model,studies the changan two brake lines ship lock reconstruction scheme of flow condition,It is proved that the flow conditions of the upper and lower approach channel and the entrance area of the first scheme of the sluice line are obviously better than that of the second scheme of the sluice line,and there is a large space for further optimization,which provides a basis for the subsequent optimization of the upper and lower approach channel.(3)Through physical model tests,measures to improve the navigable flow conditions at the entrance areas and connecting sections of the upstream and downstream approach channels of the second-line ship locks in Chang’an Junction were studied.The improvement effect of the arrangement of spur dikes,adjustment of the length and type of navigation wall,and adjustment of approach channel width and position on the flow conditions of the approach channel and the entrance area were explored,and a better modification plan and suitable navigable flow rate were determined;the river heart island was dredged,Adjust the length of the navigation wall of the approach channel,change the line type and type of the navigation wall,etc.,on the basis of effectively improving the navigable water flow conditions of the approach channel and the entrance area,further research has been done to improve the utilization efficiency of the approach channel water area and reduce the downfall.The navigation wall of the approach channel encroached on the area of the river passage,which reduced the project amount and project investment.