Gravity dam bottom hole flood discharge and energy dissipation structure considering step drop sill energy dissipation effect
By designing a step-down energy-saving structure at the bottom hole of the gravity dam, improving water flow conditions, improving energy dissipation rate, and reducing the scale of downstream energy dissipation, the problem of low flood discharge and energy dissipation rate of traditional gravity dams is solved, saving engineering investment and preventing cavitation damage.
Patent Information
- Application Number
- CN202422432558.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-10-09
AI Technical Summary
The energy dissipation rate of the traditional gravity dam is low, resulting in the need to arrange a large-scale energy dissipation work downstream, with large-scale project investment, and excessive water flow can easily cause cavitation damage on the dam surface.
Design a flood discharge and energy-elimination structure for the bottom hole of the gravity dam under the action of step drop and trough energy dissipation, including the imported section, the dam body with pressing section, the step drop and trough drainage section, and the tank protection section is adopted. The characteristics of trumpet-shaped inlet, inclined pressure plate, ventilation holes and concrete tank protection are used to form large roughness and natural ventilation, and improve water flow conditions.
The energy dissipation rate is improved, the scale of downstream energy dissipation workers is reduced, engineering investment is saved, cavitation and cavitation formation is avoided, and the water flow is used to erode the downstream river channels.
Smart Images
Figure CN223135093U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of water conservancy and hydropower engineering, in particular to a gravity dam bottom hole flood discharge energy dissipation structure considering the energy dissipation effect of stepped drops. Background Technique
[0002] In recent years, with the rapid development of dam engineering technology, higher requirements have been put forward for the flood discharge energy dissipation of gravity dams. In the design of water conservancy and hydropower projects, traditional overflow dams often use smooth surfaces for flood discharge. When the water flows down, less energy is dissipated and the energy dissipation rate is low. Most of the kinetic energy and potential energy need to be dissipated in the downstream riverbed in the form of bottom flow or flip flow and other flood discharge structures. The energy dissipation load of the bottom energy dissipator is large, so it is necessary to arrange a large-scale energy dissipator downstream, resulting in a large project investment. Moreover, the excessive flow velocity on the overflow surface is likely to cause cavitation damage to the dam surface and has strict requirements for the construction flatness. Therefore, in the design of gravity dams, it is necessary to conduct in-depth research on their flood discharge energy dissipation structures. Content of the Utility Model
[0003] Aiming at the defects existing in the prior art, the utility model provides a gravity dam bottom hole flood discharge energy dissipation structure considering the energy dissipation effect of stepped drops, which can effectively solve the above problems.
[0004] The technical scheme adopted by the utility model is as follows:
[0005] The utility model provides a gravity dam bottom hole flood discharge energy dissipation structure considering the energy dissipation effect of stepped drops, which is characterized in that, in the water flow direction, it sequentially includes an inlet section (1), a pressure section in the dam body (2), a stepped drop section (3), a flat bottom stilling basin section (4) and an apron section (5);
[0006] The inlet section (1) adopts a trumpet-shaped inlet; the top of the pressure section in the dam body (2) is in the form of an inclined pressing plate; a vent hole is arranged at the drop of the stepped drop section (3); the flat bottom stilling basin section (4) includes a stilling basin flat bottom section (4-1), stilling basin side walls (4-2) and a stilling basin end sill (4-3); the bottom of the stilling basin flat bottom section (4-1) is a flat bottom, and the stilling basin end sill (4-3) in the shape of a slope is arranged at the end of the stilling basin flat bottom section (4-1); the stilling basin side walls (4-2) are arranged on both sides of the stilling basin flat bottom section (4-1) and the stilling basin end sill (4-3).
[0007] Preferably, the cross-section of the inlet section (1) is a rectangular cross-section with three-sided contraction, and the side curve (1-1) and the top curve (1-2) of the trumpet-shaped inlet are both elliptical curves; the width of the inlet section (1) is smaller than the height, the area of the outlet cross-section is less than or equal to 0.588 times the area of the inlet cross-section, and the bottom edge inlet is rounded with an arc or an elliptical curve.
[0008] Preferably, the bottom of the pressurized section (2) of the dam body is horizontal, the two side walls are parallel, the slope coefficient of the top pressing plate section is 4-6, and an air vent (8) is arranged from the dam top at the head end of the top pressing plate section.
[0009] Preferably, the stepped drop section (3) is connected between the pressurized section (2) of the dam body and the flat-bottomed stilling basin section (4), and the bottom elevation of the pressurized section (2) of the dam body is lowered to the bottom elevation of the stilling basin flat section (4-1) of the flat-bottomed stilling basin section (4); the number of stepped drops of the stepped drop section (3) is multiple, arranged continuously along the direction of the discharging water flow, and a plurality of air vents are arranged at the stepped drops.
[0010] Preferably, the upstream slope coefficient of the stilling basin end sill (4-3) is equal to 2, and the downstream surface is vertical.
[0011] Preferably, the apron section (5) adopts a concrete apron, and the concrete strength grade is not lower than C25; tooth walls are arranged at the upstream and downstream of the apron section (5).
[0012] Preferably, the flow-through surfaces of the inlet section (1), the stepped drop section (3), and the flat-bottomed stilling basin section (4) adopt anti-scour and wear-resistant concrete, and the concrete strength grade is not lower than C25.
[0013] A gravity dam bottom hole flood discharge energy dissipation structure considering the energy dissipation effect of stepped drops provided by the present utility model has the following advantages:
[0014] The present utility model improves the water flow conditions at the inlet / outlet of the bottom hole, increases the energy dissipation rate, reduces the scale of the downstream energy dissipator, and saves the project investment. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art.
[0016] Figure 1 It is a plan view of a gravity dam bottom hole flood discharge energy dissipation structure considering the energy dissipation effect of stepped drops of the present utility model;
[0017] Figure 2 It is Figure 1 the sectional view taken along line A-A in
[0018] Figure 3 It is Figure 1 the sectional view taken along line B-B in
[0019] The reference numerals in the drawings:
[0020] 1. Inlet section; 1-1. Flared inlet side curve; 1-2. Flared inlet top curve; 2. Pressurized section of the dam body; 3. Step and drop section; 4. Flat-bottomed stilling basin section; 4-1. Flat bottom section of the stilling basin; 4-2. Side walls of the stilling basin; 4-3. End sill of the stilling basin; 5. Apron section; 6. Emergency maintenance gate slot; 7. Radial working gate; 8. Vent hole. Detailed implementation manners
[0021] In order to make the technical problems, technical solutions and beneficial effects solved by the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.
[0022] The present utility model discloses a gravity dam bottom outlet flood discharge and energy dissipation structure considering the energy dissipation effect of step and drop, which improves the water flow condition in the inlet section and makes the water flow more smooth before and after the maintenance gate slot; changes the previous strict requirements for the flatness of the overflow dam surface to form a large roughness, makes full use of the flow section length after the bottom outlet working gate, enables it to participate in energy dissipation, improves the energy dissipation rate, and reduces the scale of the downstream energy dissipator. While using step energy dissipation, natural ventilation is carried out at the bottom of the step to solve the local negative pressure problem, improve the water flow condition at the outlet, and avoid the formation of cavitation and cavitation erosion; effectively improve the water surface surge after the stilling basin, and further reduce the scouring of the downstream river channel by the discharged water flow. Therefore, the present utility model improves the water flow condition, improves the energy dissipation rate, reduces the scale of the downstream energy dissipator, and saves project investment. It provides ideas and references for the design of flood discharge and energy dissipation structures in similar projects and has certain reference significance.
[0023] As Figures 1-3 shown, a gravity dam bottom outlet flood discharge and energy dissipation structure considering the energy dissipation effect of step and drop provided by the present utility model sequentially includes an inlet section 1, a pressurized section 2 of the dam body, a step and drop section 3, a flat-bottomed stilling basin section 4 and an apron section 5 according to the water flow direction;
[0024] The inlet section 1 adopts a flared inlet; the top of the pressurized section 2 of the dam body is in the form of an inclined pressing plate; a vent hole is arranged at the drop of the step and drop section 3; the flat-bottomed stilling basin section 4 includes a flat bottom section 4-1 of the stilling basin, side walls 4-2 of the stilling basin and an end sill 4-3 of the stilling basin; the bottom of the flat bottom section 4-1 of the stilling basin is flat, and an inclined end sill 4-3 of the stilling basin is arranged at the end of the flat bottom section 4-1 of the stilling basin; side walls 4-2 of the stilling basin are arranged on both sides of the flat bottom section 4-1 of the stilling basin and the end sill 4-3 of the stilling basin.
[0025] The design features of each section are introduced in detail below:
[0026] The inlet section 1 adopts a trumpet-shaped inlet and a short pressure dam body with a sluice hole type. The cross-section of the inlet section 1 is a rectangular cross-section with three-sided contraction. The trumpet-shaped inlet side curve 1-1 and the trumpet-shaped inlet top curve 1-2 are both designed with elliptical curves. The width of the inlet section 1 is smaller than the height, and the outlet cross-sectional area is less than or equal to 0.588 times the inlet cross-sectional area. The bottom edge of the inlet is rounded with an arc or an elliptical curve. As a specific structure, the trumpet-shaped inlet side curve 1-1 adopts a 1 / 4 elliptical curve, that is, x 2 / a 2 +y 2 / b 2 = 1, where a / b = 3, and the trumpet-shaped inlet top curve 1-2 is designed with a 1 / 4 elliptical curve as a whole.
[0027] The bottom of the pressure section 2 of the dam body is horizontal, the two side walls are parallel, and the top is an inclined pressing plate. The slope coefficient of the top pressing plate section can be taken as 4-6, and an air vent 8 is arranged from the dam top at the head end of the top pressing plate section. In practical applications, an accident overhaul gate slot 6 is arranged on the upstream side of the top pressing plate section, and an arc-shaped working gate 7 is arranged on the downstream side.
[0028] The stepped drop section 3 is connected between the pressure section 2 of the dam body and the flat-bottomed stilling basin section 4, and the bottom plate elevation of the pressure section 2 of the dam body is lowered to the bottom plate elevation of the stilling basin flat section 4-1 of the flat-bottomed stilling basin section 4. The number of stepped drops in the stepped drop section 3 is multiple, and they are arranged continuously along the direction of the discharging water flow. Multiple air vents are arranged at the stepped drops, and the layout positions should be as close as possible to the bottom plate upwards.
[0029] The flat-bottomed stilling basin section 4 includes a stilling basin flat section 4-1, stilling basin side walls 4-2, and a stilling basin end sill 4-3. The bottom of the stilling basin flat section 4-1 is flat, and a sloped stilling basin end sill 4-3 is arranged at the end of the stilling basin flat section 4-1. Stilling basin side walls 4-2 are arranged on both sides of the stilling basin flat section 4-1 and the stilling basin end sill 4-3. As a specific structure, the upstream slope coefficient of the stilling basin end sill 4-3 is equal to 2, and the downstream surface is vertical.
[0030] The apron section 5 adopts a concrete apron, and the concrete strength grade is not lower than C25. The thickness of the apron section 5 is 1.0 m, and tooth walls with a certain depth are arranged upstream and downstream of it.
[0031] The bottom hole flow-through surface, including the flow-through surface of the inlet section 1, the flow-through surface of the stepped drop section 3, and the flow-through surface of the flat-bottomed stilling basin section 4, etc., adopts anti-scour and wear-resistant concrete, and the concrete strength grade is not lower than C25.
[0032] In summary, the present utility model discloses a gravity dam bottom hole flood discharge and energy dissipation structure considering the energy dissipation effect of stepped drops, mainly including an inlet section, a pressure section of the dam body, a stepped drop section, a flat-bottomed stilling basin section, and an apron section, and has the following characteristics:
[0033] (1) The inlet section adopts a flared inlet. The overall curve at the top of the inlet section is designed as an elliptical curve, which improves the water flow conditions in the inlet section and makes the water flow more smooth before and after the maintenance gate slot;
[0034] (2) The pressure section of the dam body is connected to a stepped drop section below. An air vent is provided at the drop. This stepped drop energy dissipation structure changes the previous strict requirements for the flatness of the overflow dam surface, forms a large roughness, makes full use of the flow section length after the bottom hole working gate, enables it to participate in energy dissipation, improves the energy dissipation rate, and reduces the scale of the downstream energy dissipator. While using the stepped energy dissipation, natural ventilation is carried out at the bottom of the steps, solving the local negative pressure problem, improving the outlet water flow conditions, and avoiding the formation of cavitation and erosion;
[0035] (3) The structural stilling basin adopts a flat-bottom stilling basin. A flat section is provided at the bottom of the basin, and a sloping tail sill is provided at the end, effectively improving the water surface surge after the stilling basin, and thus reducing the scour of the downstream river by the discharged water flow;
[0036] (4) A concrete apron is provided downstream of the tail sill of the flat-bottom stilling basin to ensure the structural safety of the sill foot.
[0037] The utility model improves the water flow conditions at the inlet / outlet of the bottom hole, increases the energy dissipation rate, reduces the scale of the downstream energy dissipator, and saves project investment.
[0038] Taking the flood discharge and energy dissipation structure of the bottom hole dam section of a certain gravity dam project adopting the technical solution of the utility model as an example, it is further described in combination with the attached drawings:
[0039] As shown in the Figure 1 attachment, in a certain gravity dam project, a bottom hole dam section is provided in the overflow dam section for reservoir flood discharge and emptying. The bottom hole adopts the type of a short pressure dam body discharge hole, and the flow-through surface is made of anti-scour and wear-resistant concrete C35. The flood discharge and energy dissipation structure of the bottom hole dam section of the gravity dam project includes an inlet section 1, a pressure section 2 of the dam body, a stepped drop section 3, a flat-bottom stilling basin section 4, and an apron section 5 arranged in sequence along the water flow:
[0040] The bottom elevation of the inlet section 1 is 128.00m, and it adopts a flared inlet. To make the water flow more smooth before and after the accident maintenance gate slot 6, the side curve 1-1 of the flared inlet is a 1 / 4 elliptical curve, and the curve equation is x 2 / 4.5 2 +y 2 / 1.5 2 =1. The top curve 1-2 of the flared inlet is a 1 / 4 elliptical curve, and the curve equation is x 2 / 5.15 2 +y 2 / 2.566 2 =1. The bottom edge inlet is rounded with a circular arc with R = 1m.
[0041] One emergency repair gate slot 6 and one radial working gate 7 are arranged in the pressurized section 2 of the dam body. An air vent 8 is set from the dam top at the head part of the pressurized section 2 of the dam body. The orifice size of the emergency repair gate slot 6 is 6.0m×9.0m, and the orifice size of the radial working gate 7 is 6.0m×7.0m. A pressing plate section is adopted behind the emergency repair gate slot 6, the slope of the pressing plate section is 1:4, and the length is 8.0m.
[0042] In order to make full use of the flow section length after the radial working gate 7 at the bottom hole, make it participate in energy dissipation, reduce the size of the downstream flat-bottom stilling basin section 4, and reduce the downstream energy dissipation load, a stepped drop section 3 is connected downstream 6.263m from the radial working gate 7. The stepped drop section 3 includes multiple and continuous stepped drops, the bottom elevation is lowered from 128m to 115m, each step is 1.5m long and 1.5m high, and the last step is 1m high. To solve the problem of local negative pressure in the stepped drop, improve the outlet water flow condition, and avoid the formation of cavitation and cavitation erosion, 4 vent holes with a diameter of 25cm are evenly arranged 30cm downward from the bottom plate at the elevation of 128m. The elevation of the vent hole arrangement is close to the 128m bottom plate upward to avoid being submerged by the water body in the stilling basin.
[0043] Behind the stepped drop section 3 is the flat-bottom stilling basin section 4, which includes a stilling basin flat-bottom section 4-1, stilling basin side walls 4-2 and a stilling basin end sill 4-3; the width of the stilling basin flat-bottom section 4-1 is 27.0m and the length is 55m. The top elevation of the stilling basin side walls 4-2 is 134m, the top width is 2m, the bottom width is 9m, the water-facing side is vertical, and the backwater side is vertical above the elevation of 132m and has a slope of 1:0.3 below. At the end of the stilling basin flat-bottom section 4-1, a stilling basin end sill 4-3 with an upstream slope of 1:2 and a vertical downstream surface is set, with a height of 4m.
[0044] Behind the stilling basin end sill 4-3 of the flat-bottom stilling basin section 4 is connected to a apron section 5 with a length of about 25m. The apron section 5 is made of concrete with a strength grade not lower than C25. The depth of the upstream cut-off wall of the apron is 6m, and the depth of the downstream cut-off wall is 2m, which effectively improves the water surface surging after the stilling basin, and further reduces the scouring of the downstream river channel by the discharging water flow.
[0045] The utility model discloses a flood discharge energy dissipation structure for a gravity dam bottom hole considering the energy dissipation effect of a stepped drop weir, which improves the water flow condition in the inlet section and makes the water flow more smooth before and after the accident maintenance gate slot; changes the previous strict requirements for the flatness of the overflow dam surface to form a large roughness, makes full use of the flow section length after the bottom hole working gate to participate in energy dissipation, improves the energy dissipation rate, reduces the scale of the downstream energy dissipator, and saves project investment. While using the stepped energy dissipation, natural ventilation is carried out at the bottom of the steps to solve the local negative pressure problem, improve the water flow condition at the outlet, and avoid the formation of cavitation and erosion; effectively improve the water surface surging after the stilling basin, and further reduce the scouring of the downstream river by the discharging water flow. It provides ideas and references for the design of flood discharge energy dissipation structures for similar projects and has certain reference significance.
[0046] The embodiments described above are only used to illustrate the technical ideas and characteristics of the present utility model. The purpose is to enable those skilled in the art to understand the content of the present utility model and implement it accordingly. The patent scope of the present utility model cannot be limited only by this embodiment. That is, any equivalent changes or modifications made to the spirit disclosed by the present utility model still fall within the patent scope of the present utility model.
Claims
1. A bottom outlet flood discharge energy dissipation structure of a gravity dam considering the energy dissipation effect of a stepped drop, characterized in that, In the water flow direction, it successively includes an inlet section (1), a pressurized section of the dam body (2), a stepped drop section (3), a flat-bottomed stilling basin section (4), and an apron section (5). The inlet section (1) adopts a trumpet-shaped inlet; the top of the pressurized section of the dam body (2) is in the form of an inclined pressing plate; vent holes are provided at the drop of the stepped drop section (3); the flat-bottomed stilling basin section (4) includes a flat bottom section of the stilling basin (4-1), side walls of the stilling basin (4-2), and a tail sill of the stilling basin (4-3); the bottom of the flat bottom section of the stilling basin (4-1) is flat, and the tail sill of the stilling basin (4-3) in the shape of a slope is arranged at the end of the flat bottom section of the stilling basin (4-1); the side walls of the stilling basin (4-2) are arranged on both sides of the flat bottom section of the stilling basin (4-1) and the tail sill of the stilling basin (4-3).
2. The energy dissipation structure of the bottom outlet of the gravity dam considering the energy dissipation effect of the stepped drop weir according to claim 1, characterized in that, The cross-section of the inlet section (1) is a rectangular cross-section with three-sided contraction, and both the side curve (1-1) of the trumpet-shaped inlet and the top curve (1-2) of the trumpet-shaped inlet are elliptical curves; the width of the inlet section (1) is smaller than the height, the outlet cross-sectional area is less than or equal to 0.588 times the inlet cross-sectional area, and the bottom edge inlet is rounded with an arc or an elliptical curve.
3. The energy dissipation structure of the bottom outlet of the gravity dam considering the energy dissipation effect of the stepped drop is characterized in that, The bottom of the pressurized section of the dam body (2) is horizontal, the two side walls are parallel, the slope coefficient of the top pressing plate section is 4 to 6, and vent holes (8) are arranged from the dam top at the head end of the top pressing plate section.
4. A bottom outlet flood discharge energy dissipation structure of a gravity dam considering the energy dissipation effect of a stepped drop weir according to claim 1, characterized in that, The stepped drop section (3) is connected between the pressurized section of the dam body (2) and the flat-bottomed stilling basin section (4), and the bottom elevation of the pressurized section of the dam body (2) is dropped to the bottom elevation of the flat bottom section of the stilling basin (4-1) of the flat-bottomed stilling basin section (4); the number of stepped drops of the stepped drop section (3) is multiple, which are continuously arranged along the direction of the discharged water flow, and multiple vent holes are provided at the stepped drops.
5. A bottom orifice flood discharge energy dissipation structure of a gravity dam considering the energy dissipation effect of a stepped drop, characterized in that, The upstream slope coefficient of the tail sill of the stilling basin (4-3) is equal to 2, and the downstream surface is vertical.
6. The energy dissipation structure of the bottom outlet of a gravity dam considering the energy dissipation effect of a stepped drop is characterized in that, The apron section (5) adopts a concrete apron, and the concrete strength grade is not lower than C25; tooth walls are arranged at the upstream and downstream of the apron section (5).
7. A bottom orifice flood discharge energy dissipation structure of a gravity dam considering the energy dissipation effect of a stepped drop, characterized in that, The flow-through surfaces of the inlet section (1), the stepped drop section (3), and the flat-bottomed stilling basin section (4) adopt erosion-resistant and wear-resistant concrete, and the concrete strength grade is not lower than C25.