Study On The Hydrodynamics And Sediment Characteristics Of Desilting Facilties In Deep Water Reserviors

Xiaolangdi hydraulic project is one of the main works in sediment discharge regulation system in Yellow River, which is also located on the key position of controlling water and sediment to downstream. It plays an very important strategic role in harness and development of Yellow River.At present, how to get the reasonable and effective sediment treatment measures and ways of sediment release and desilting to reduce the sedimentation in reservoir and alleviate the loss ratio of reservoir storage, has been a big problem needed to solve urgently in the case of the contradiction between the water using and dredging.This article puts forward a new sedimentation structure, the new type of the arrangement of sediment building"Forward-extended sand-flushing gallery", and a new pattern of sediment desilting,"the Integration of mechanical dredging and desilting tunnel of Xiaolangdi project", thus the better solutions would be found for the dredging problems of Xiaolangdi Hydraulic Project in deep water.The main work of this paper can be concluded as follows:(1) On the base of the desilting tunnel having been built, a new type of layout of sediment structure,"Forward-extended sand-flushing gallery", and a new pattern of sediment desilting,"the Integration of mechanical dredging and desilting tunnel of Xiaolangdi project", are put forward in the paper to get the better solutions to the desilting problems of Xiaolangdi.(2) Three-dimensional numerical model of forward-extended sand-flushing gallery is established to compute the pressure and velocity distributions in the flushing gallery and sediment tunnel in the case of the different working conditions of the orifice gates opening. Through the calculations, the distribution laws and changing trends are found and compared with the results of the model test. The comparison results show that the numerical model has higher accuracy.(3) Through the model tests, the pressure distributions in the flushing gallery and sediment tunnel, in the case of the different working conditions of the orifice gates opening, are studied and analyzed. The pressure distribution laws and changing trends are gained through the results of the preliminary and dimensionless analysis, and also the graph of the relationship among the pressure and water level and flux of several measuring points.(4) The model tests of the integration of mechanical dredging and desilting tunnel of Xiaolangdi project have been taken. And the efficiency and the amount of sluicing sediment are studied with the different hydrodynamic conditions and different diameter of pipe. By the analysis of the results of the tests, the non-dimensional graphs of the relationship among the sediment concentration in muddy water from pipe and water level, pipe diameter and pipe length, which could provide the references for the choice of the integral sediment pattern.