| With a total length of about 100 kilometers,the Yinhan-Jiweinan Main Line is a huge water conveyance system composed of open flow water conveyance structures such as tunnels,inverted siphon and box culverts,and control structures such as control gates,separation gates and withdrawal gates.Due to its long water transmission line,wide water supply range and complicated hydraulic control process,there are various unstable phenomena in the actual operation of the channel.In order to ensure the stable and safe operation of the channel in the actual operation process,the hydraulic control simulation of various typical working conditions is carried out in advance to reveal the influence of the opening degree,opening and closing speed and control amplitude of the gate on the water flow movement in the channel during the control process of the gate,and the internal mechanism of the interaction of the water flow in the sequence of different opening and closing combinations of the gate.A pre-plan library for gate control of unsteady flow in South Main line water transmission system is formed,which provides reference for formulating emergency dispatching strategy of open channel water supply.In this paper,a one-dimensional hydrodynamic model of typical channel sections in the Weinan Trunk Line of Yinhan-Ji River was constructed using MIKE11 software,and different hydraulic response processes of each typical channel section were simulated in the process of hydraulic regulation.The changes of water level of Huangwu tunnel section under two operating modes of constant water level operation and equal volume operation in the downstream were studied.This paper explores the water level fluctuation propagation of single gate and double gate under different control modes during normal operation of the box and Han section,analyzes the water level fluctuation of the accident channel section and adjacent channel section in the abnormal operation of Shaoling Yuan tunnel,and summarizes the changes of channel water level in different typical channel sections under different discharge,different adjusting speed and closing time of gate and different operation modes.(1)The differences between the equal volume operation mode and the downstream constant water level operation mode are compared and analyzed from three aspects:the water level fluctuation time of each section,the maximum amplitude of water level and the time required to reach the new balance.According to the characteristics of the two operation modes,the equal volume operation mode has a high water level downstream of the midpoint,and a pressure flow is formed in the Huangwu tunnel,The water level in front of the gate is in the open channel flow state when the downstream constant water level is running.Therefore,the Huangwu tunnel should be operated at the downstream constant water level.(2)The unsteady flow processes of single gate and double gate under different working conditions are different.When the single gate is running,the water level in front of the gate does not fluctuate,and the fluctuation range of the water level after the gate increases with the increase of the gate running speed and the water level oscillation time decreases.When the double gate is running,the water level of each section begins to decline at different speeds due to the increase of the gate opening.Changing the flow rate will not change the water level change law of each section of the channel.(3)It is assumed that the upper and lower sluice gates in Shaoling Yuan tunnel are closed with different closing time and different closing methods.The longer the sluice closing time,the slower the rise or fall of the water level in the accident section.The operation mode of the gate has little effect on the fluctuation rule of the water level in the accident channel or adjacent channel,but has great effect on the stable water level in the accident channel. |
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