Study On Water Conveyance System Layout And Hydraulics Of Lock With Large Scale And Middle-low Water Head

With the increase of freight volume and the trend of large-scale lock,our country is rebuilding and expanding a large number of second-line and even the three or four line locks,in which the lock with large scale and middle-low water head occupy a large proportion.This paper studied the water conveyance system layout and hydraulics of lock with large scale and middle-low water head lock based on the newly built Qingyuan second-line lock.The head of Qingyuan second-line lock is not high,but it has large plane scale,high water strength and large volume.The problems about filling and discharging time、the berthing condition of the lock and the waterway navigation hydraulics of upper and lower approach channels are very serious.How to make the newly second-line lock efficient,safe,smooth operation and solve a series of hydraulic problems in the operation process of the conveyance system layout are very necessary.This paper studies on the water conveyance system of and puts forward optimization measures based on the 1:30 overall hydraulic model of Qingyuan second-line lock.This paper solves navigation hydraulics problems about the two line locks have common part of the upper and lower approach channels by establishing mathematical model about approach channels and simulating the process of lock chamber filling and discharging,at the same time,it provides scientific basis for the operation design of the lock.The experimental results showed that:This paper has researched the layout of the water conveyance system、chamber energy dissipater and the effect to flow conditions of chamber and approach channel、ship berthing conditions、ship mooring force in different lock filling and drainage ways through physical model tests and mathematical model calculations.Besides,a new high-efficiency type of energy dissipater combined with baffle sill and baffle beam is proposed,solving the problem of transverse flow misdistribution in which water conveyance system applies long culverts with side holes in lock wall of large scale lock.The berthing conditions is better,ship mooring force is smaller after optimizing the layout of energy dissipater in water filling process.The adjustments and optimization of the inlet line according to the characteristics of the two line locks having common part approaches improve the inlet flow conditions in water filling process.Adjustments of outlet and guidance wall of second-line lock according to the characteristics of water flow in the lower approach channels improve the flow conditions and meet the requirements of navigation flow conditions in discharging process.Results of two dimensional numerical simulation in unsteady flow show that:Water level value of rising and dropping are small and the velocity of berthing space ranges from 0.2m/s to 0.6 m/s in water filling process of second-line lock.when the second-line lock discharging,the maximum velocity at lower approach channel parking section of second-line lock ranges from 0.527m/s to 0.848 m/s and the maximum longitudinal velocity at lower approach channel of first-line lock is 0.266m/s.There is no obvious reflux and constant current,besides the flow conditions are better.