Facility for eliminating negative pressure of bottom plate at torrent diffusion slope-variable section of flood discharging tunnel

Abstract

The invention relates to a facility for eliminating the negative pressure of a bottom plate at a torrent diffusion slope-variable section of a flood discharging tunnel, The facility comprises a step-down floor and pressing holes, wherein the step-down floor is arranged in front of a negative pressure region of the bottom plate at a diffusion section of the flood discharging tunnel; the pressing holes are arranged at two ends of the step-down floor outside a side wall of the flood discharging tunnel; a hollow cavity formed between a jet flow surface generated by discharged water in the flood discharging tunnel flowing across the step-down floor and a step-down floor bottom plate surface is communicated with air through the pressing holes so that the negative pressure of the bottom plate of the flood discharging tunnel is reduced and partial damage of the bottom plate of the flood discharging tunnel is avoided. In general, the step-down floor height is 0.30-1.00m, and the sizes of the pressing holes are determined by factors, such as the step-down floor height, step-down floor aerating capacities, a negative pressure region range and the like. A physical model test result shows that the pressing facility provided by the invention can be used for effectively eliminating a negative pressure value of the bottom plate at the torrent diffusion section of the flood discharging tunnel, increasing water flow aerating concentration and improving the energy dissipation effect of a stilling basin.

Description

technical field [0001] The invention relates to a measure for eliminating the negative pressure on the bottom plate of a flood discharge tunnel in a water conservancy and hydropower project, more specifically, a measure for eliminating the negative pressure on the bottom plate of a high Froude number flood discharge tunnel where the rapid flow diffuses and slopes. Background technique [0002] The flood discharge structure is an important part of the hydropower station, accounting for about 1 / 3 of its total investment, so the operation safety of the flood discharge structure is very important for the entire hydropower station hub. At present, the main flood discharge structures include dam body spillway (spill hole), bank spillway (spill tunnel) and emptying tunnel. For the bank spillway, in order to reduce the excavation investment, the shape of the bottom slope is usually arranged in the form of connecting slope curves according to the actual terrain. When underflow energ...

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Problems solved by technology

[0003] From the outlet of the spillway tunnel to the diverging slope section between the stilling basin, the flow velocity of the high-head spillway tunnel can reach more than 35m / s. , it is easy to cause a local negative pressure area (and the negative pressure value is relatively large) to be formed in a certain range on the bottom plate of the diffusion-changing section. , thus affecting the safety of the entire drainage structure

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