Research On Navigation Flow Conditions Of The Approach Channel Of Expansion Lock Of Narrow River In Mountainous Area

With the increasing demand for shipping,in order to improve the passing capacity of the mountain channel,the reconstruction and expansion of the lock project has been carried out one after another.Due to the influence of topographic river conditions,navigation buildings are difficult to be arranged and navigation flow conditions are extremely complex,so it is necessary to study the key problems existing in the layout of renovated and expanded locks and their effects on the flow conditions of the hub and approach channel.Due to the steep terrain and compact layout in the narrow river in mountainous areas,the proportion of the river crossing area occupied by the reconstruction and expansion of the lock project is often large,which will cause the water level in front of the dam to rise and affect the flood control security and normal operation of the hub.At the same time,due to the influence of the narrow river regime in mountainous areas,the entrance area of the approach channel is easy to be in the mainstream area of the channel,and the flow direction has a large included Angle with the center line of the channel,resulting in a large flow velocity,strong oblique flow and poor navigable flow conditions.The approach channel is an important connection part between the lock and the river course,and its good flow condition is the prerequisite for the ship(team)to pass through the lock safely.Therefore,narrow river in the mountainous area shiplock engineering layout should not reduce the reconstruction and hub flood discharge capacity,water does not affect the power stations,and not deteriorate entrance area and connection section of the navigation flow condition,does not affect existing lock safe,will not affect the normal navigation during the construction of a comprehensive comparison to determine,in many limiting factors,find the main contradiction and take the corresponding improvement measures,finally be impact on various aspects are relatively small.In this paper,based on a typical narrow river in mountain area shiplock expansion project of Shan Xiu,by the combined research method of the mathematical model of the physical model to study the layout scheme of shiplock reconstructed and expaned for flood discharge in river,discharge of hub,and the influence of the power plant water intake,and proposes the corresponding improvement measures,effectively reduce the water level before dam indicates high,reduces the hub for discharge capacity of the proposed expansion project and the influence of water condition.On this basis,a comparative study on the layout scheme of the upstream approach channel was carried out,and a relatively good layout scheme of navigable flow condition was obtained,which provided technical support for engineering design and reference and experience for similar projects.The main results of this paper are as follows:(1)The narrow reach of the river in the mountainous area is steep in terrain and compact in layout.It is advisable to choose the centralized layout for the reconstruction and expansion of the lock,which can reduce the amount of excavation,construction difficulty and project investment.(2)In this study,aiming at the problem of large flood discharge section occupying the channel in the upper approach channel of shanxiu reconstruction and expansion lock,a relatively optimal excavation and dredging scheme(second-level platform excavation)was proposed byusing the two-dimensional mathematical model and through the comparative analysis and calculation of multiple schemes,so as to basically eliminate the influence on flood discharge in the channel and discharge from the hub.(3)Through the physical model test,the improvement measures of navigable flow conditions in the upper approach channel and the entrance area of shanxiu junction were studied.The flow conditions of the approach channel and the entrance gate are effectively improved by means of air permeation in the lower half of the separated flow barrier near the sluice section,the single-dive dam to block the deep channel of the approach channel and the length of the guard wall of the approach channel.