Step spillway with pre-aeration structure and construction method

Abstract

The invention discloses a step spillway with a pre-aeration structure and a construction method. The step spillway comprises a plurality of steps, the pre-aeration structure is arranged at a water outlet of a certain step on the upstream of a step spillway aeration occurrence point, and when incoming flow is torrent, water flow passes through a contraction side wall to form a jet flow water tongue. The step spillway is simple in structure, under the condition that the pre-aeration structure parameter value is reasonable, the jet flow water tongue can be formed under all incoming flow conditions, the jet flow water tongue aerates the bottom and the side direction of the water flow from a bottom cavity and a side cavity, and therefore the full-section aeration effect is achieved. The contraction type pre-aeration structure can provide the aeration water flow with the aeration concentration higher than 2%, the pre-aeration water flow with sufficient aeration is provided for the downstream step, the aeration blind area of the step spillway is greatly reduced, cavitation erosion damage of the step spillway is prevented, and the application range of the step spillway is enlarged.

Description

technical field [0001] The invention relates to the technical field of drainage structures, in particular to a stepped spillway with a pre-aeration structure. Background technique [0002] In many forms of discharge structures, the stepped spillway can dissipate the energy of the discharge along the way, thereby greatly reducing the length of the stilling pool that needs to be built downstream, thereby reducing the cost of the entire project. The stepped spillway has been widely used Water conservancy and hydropower projects. Usually, self-aeration can occur on the surface of the water flow on the stepped spillway, and the water flow downstream of the aeration point is aerated flow, which reduces the cavitation damage of the spillway. However, under the flow of large single width (more than 60m 2 / s), the aeration point on the stepped spillway will move downstream significantly, resulting in a large-scale aeration blind zone (clear water area) on the stepped spillway. Whe...

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Problems solved by technology

[0004] In order to eliminate the aeration blind area upstream of the stepped spillway, traditional aeration facilities, such as ventilation holes, drop ridges and pick-up ridges, are arranged upstream of the stepped spillway in the prior art. Although the ventilation holes can ensure the smoothness of the ventilation line, their holes The mouth is easy to block, which affects the aeration effect; when the drop and pick-up work under the condition of large flow, due to the effect of gravity, the phenomenon of backwater in the cavity is serious, and the aeration effect is not good.

Therefore, traditional aeration facilities cannot solve the problem of cavitation and erosion in stepped spillways under large single-width flows

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