Study On Some Hydraulic Problems For Sluiceway About Reservoirs In Sediment-Laden River

The sediment concentration of river is higher in the northern China,builting reservoirs on sediment-laden river, arrangement of flood discharge and sediment-flushing structure is one of the main problems which need to be considered. Based on analysising the present situation and causes of sedimentation problem of reservoirs preliminarily, summarizing the layout features of sediment-laden river reservoir project, expound the main technical problems of sluiceway at the design and operational stage.Take the Tingkou reservoir as a example, analyse its hydrological and sediment conditions and operation mode,reaserch the principle and method to determine discharging capacity,hydraulic characteristics and form of flood-releasing energy dissipator and sediment-flushing structure of sluiceway in sediment-laden river.Reasonable discharging capacity is fundamental guarantee for sediment-laden river reservoirs to retain active storage capacity and obtain comprehensive benefits in long-term. Through the describing of discharge capacity of hydro-junction and desilting tunnel, analyse the main influencing factors.Contrast present methods,suggest to use the discharge of the channel formation as the reference of discharging capacity , consider characteristics of runoff and sediment, reservoir operation mode, reservoir boundary conditions, sediment transport flow pattern etc,put forward the principle and calculation method with the above four factors for correction coefficients. Based on the established methods to calculate discharging capacity of sluiceway about Tingkou reservoir.As a form of reservoir outlet passage, whether the sluiceway's hydraulic characteristics meet the need is the main problem in the design stage under different operation condition.In this paper,with the Tingkou reservoir sluiceway as an example, build the normal hydraulic integral model with geometric scale of 1:50 in laboratory, research the hydraulic characteristics problem such as water flow regime of inlet, conveyance capacity, pressure and velocity distribution of hole body of tunnel etc. by using model test method.Optimize the body conformation of inlet,make it meet the need of reservoir operation.Due to the influence of higher outflow sediment concentration, design of energy dissipation and erosion prevention of sluiceway on sediment-laden river have some special requirements. Combining the sesign and operation of Tingkou and Sandaowan project, discusse the solution to related issues. Sluiceway have operating frequently and great variation range of the water level and discharge characteristics, energy dissipator need to meet different operation condition,especially to pay attention to the special requirements of energy figure when reservoir sediment flushing. Analysis shows that whether adopting trajectory energy dissipation or energy dissipation by hydraulic jump,dentated sills can reduce scouring downstream channel obviously;for the problem of processing different discharge conditions and effect of energy dissipation at the same time,can use diffusion type arc and dentated sills to solve.