A Method for Determination of Sediment Carrying Ratio in Water Body of Drain Channel and Forebay of Pumping Station

Abstract

The invention relates to a determination method for sediment carrying capacity of a pumping station approach channel and a forebay water body. The determination method comprises the following steps: 1) determining a relation of flow rates of the pumping station approach channel and the forebay water body along with time variation; 2) calculating the maximum Shields number thetam, the friction factor f and the roughness height kN of the pumping station approach channel and the forebay water body; 3) calculating the silt settling velocity w of the pumping station approach channel and the forebay water body and a specific value Psi of the sediment time and the flow period of silt in a silt conveying layer; 4) calculating the phase drift Psi of silt flow velocity and silt phase residues alpha of the pumping station approach channel and the forebay water body; and 5) calculating the sediment carrying capacity delta / D of the water body represented by a dimensionless erosion depth of the pumping station approach channel and the forebay water body.

Description

technical field [0001] The invention relates to a method for determining the sand-carrying ratio of water body in a diversion channel and a forebay of a pumping station, and belongs to the field of hydraulic engineering pumping stations. Background technique [0002] In the unsteady flow of the diversion channel and the forebay of the pumping station, the sediment-carrying rate of the water body changes dynamically. Such as figure 1 As shown, the sediment volume concentration S(y) is represented by a dotted line, which changes with the flow velocity U, where y is the vertical coordinate, y=0 is the initial bed surface, the subscript m represents the maximum value, and Δ is the erosion depth, namely The distance from the surface of the saturated sand layer to the initial bed surface, S m The product of Δ and Δ is the total volume of sediment involved in the movement, that is, the sediment-carrying rate of the water body. [0003] Accurately knowing the size of the sediment...

AI Technical Summary

Problems solved by technology

The sediment-carrying rate of water body widely used in current projects is derived based on the theory of constant flow, which does not include the effect of phase difference, and cannot reflect the time response of the sand-carrying rate of water body in the process of unsteady flow relative to the hydrodynamic conditions. This will fail to reflect the phase shift of the relative flow velocity of the sediment movement and the phase residue of the total amount of moving sediment after the flow velocity is reduced, and will also lead to an underestimation of the mean value of the sediment carrying rate of the water body

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