Energy dissipation connection structure for connecting natural riverway based on surface flow energy dissipation and flood discharge and energy dissipation structure of vertical shaft flood discharge tunnel

Abstract

The invention relates to an energy dissipation connection structure for connecting a natural river channel based on surface flow energy dissipation and a flood discharge and energy dissipation structure of a vertical shaft flood discharge tunnel. The energy dissipation connection structure for connecting the natural river channel based on surface flow energy dissipation comprises a reverse slope apron located behind a drainage building and a step section connected with the reverse slope apron. The drainage building is connected with a section of down slope, the gradient of the down slope is the gradient of the riverbed, a reverse slope apron is connected behind the down slope, the picking angle theta of the reverse slope apron is 3-6 degrees, the picking angle theta comprises an endpoint value, the gradient i of the reverse slope is 1: 10-1: 15, the gradient i comprises an endpoint value, and the drop sill height a of the reverse slope apron is lower than the maximum downstream water depth of the energy dissipation anti-scour flood standard; the back of the reverse slope apron is connected with a step section, the slope angle beta of the step section is 5-10 degrees, the slope angle beta comprises an endpoint value, the slope i step of the step surface of the step section is 1: 5-1: 10, and the slope i step comprises an endpoint value.

Description

Technical Field

[0001] The present invention relates to the technical field of energy dissipation for surface flow energy dissipation, and in particular to an energy dissipation connection structure for connecting natural river channels and a vertical shaft flood discharge tunnel flood discharge energy dissipation structure based on surface flow energy dissipation. Background Art

[0002] Water flows in natural river channels are generally slow. To achieve various water conservation goals, it is often necessary to construct sluice gates, dams, and other drainage structures to control water flow. These structures typically concentrate outflow from sluice gates, waterfalls, spillways, and tunnels, increasing the flow per unit width, concentrating energy, and increasing destructive power. This further complicates the planar distribution of downstream water flow, disrupting the original equilibrium between the flow and the riverbed boundary. This causes the impact force of the water to exceed the boundary's ability to resist impact, leading to scour of the riverbed.

[0003] To ensure the safety of buildings and prevent the adverse effects of downstream water on other hub structures and the riverbed, it is necessary to properly connect the water flow with the natural river. Generally, there are three ways to connect the water flow: the first is to use bottom flow energy dissipation, the second is to use diversion flow energy dissipation, and the third is to use surface flow energy dissipation.

[0004] Surface flow energy dissipation involves creating a drop-off below the downstream water level at the end of the spillway structure. This directs the high-speed water flow into the upper layers of the downstream flow, creating a large bottom vortex between the main stream and the riverbed, preventing the main stream from directly eroding the riverbed. Surface flow energy dissipation primarily eliminates excess energy through water diffusion, velocity distribution adjustment, and the intense turbulence of the bottom vortex. In the transition section, since the high-speed main stream is located at the surface, it is called surface flow energy dissipation.

[0005] The traditional surface flow energy dissipation method is applicable only when the downstream water depth is deep and the water level fluctuates slightly with the seasons. Because the main current is on the surface, traditional surface flow energy dissipation facilitates the rapid discharge of floating debris through surface flow, thus avoiding impact with the dam surface and apron. In addition, because the main current is on the surface, it has little scouring effect on the riverbed, and no anti-scouring measures are required, which can save engineering investment. Using the traditional surface flow energy dissipation method, the downstream water surface fluctuates violently, which is detrimental to the stability of the bank slope and navigation. Moreover, when the amount of water discharged is small and the downstream water depth fluctuates significantly below the drop-sill elevation, the discharged water can easily fall directly from the surface flow into the downstream river channel, changing from the original surface flow to the bottom flow. The water flow will directly impact the downstream riverbed, causing scouring, and thus endangering the safety of the flood discharge structure.

[0006] When the drop-sill height a = 0, the downstream water depth ht > the post-jump water depth h″ is a necessary condition for generating a surface flow regime. Due to the complex discharge conditions within the project, the magnitude of the discharge varies from time to time, ranging from a major flood that occurs once every 2,000 years to a minor flood that occurs once every two years. Changes in the discharge flow rate cause significant variations in the downstream water depth. Given the same drop-sill height, it is generally difficult to adapt to changes in the downstream water level, ensuring that the connection between the discharge of the discharge structure and the natural river water level is in the ideal surface flow state. Summary of the Invention

[0007] In order to solve the above problems, the purpose of the present invention is to provide an energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation and a vertical shaft flood discharge tunnel flood discharge energy dissipation structure. The above energy dissipation structure dissipates energy based on the surface flow energy dissipation principle, improves the energy dissipation rate, and has strong adaptability to changes in downstream water flow, and can adapt to changes in water levels in downstream river sections.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] As one aspect of the present invention, the present invention provides an energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation, comprising a reverse slope guard located behind a water discharge structure and a stepped section connected to the reverse slope guard; a section of downslope is connected to the rear of the water discharge structure, the slope of the downslope is the slope of the riverbed itself, followed by a reverse slope guard, the pick angle θ of the reverse slope guard is 3° to 6°, the pick angle θ includes the endpoint value, and the slope of the reverse slope i 反坡 The slope is 1:10~1:15, and the slope is 反坡 Including the endpoint value, the drop height a of the reverse slope protection tank is lower than the maximum water depth downstream of the energy dissipation and flood prevention standard; the reverse slope protection tank is connected to the step section, the step section includes more than one step, the slope angle β of the step section is 5°~10°, the slope angle β includes the endpoint value, and the slope i of the step surface of the step section is 阶梯 The slope is 1:5~1:10, and the slope i 阶梯 Contains the endpoint value.

[0010] Furthermore, the ratio of the step height d of each step of the step section to the relative critical water depth hc is less than 0.8, and the step height of the highest step of the step section is calculated downward from the elevation of the top of the anti-slope protection tank.

[0011] Furthermore, the step height d of each step of the step section is 1.0 to 1.5 m, and the step height d includes the endpoint value. The step height of the highest step of the step section is calculated downward from the elevation of the top of the anti-slope protection tank.

[0012] Furthermore, the drop height a of the anti-slope protection apron is 3 / 4 of the maximum water depth downstream of the energy dissipation and flood prevention standard.

[0013] Furthermore, the maximum downstream water depth of the energy dissipation and flood prevention standard is the maximum downstream water depth of a flood that returns once every 100 years.

[0014] As another aspect of the present invention, the present invention further provides a vertical shaft flood discharge tunnel flood discharge energy dissipation structure, the vertical shaft bottom of the vertical shaft flood discharge tunnel is connected to the energy dissipation well, the connection between the vertical shaft and the energy dissipation well is connected to the water withdrawal tunnel, the water withdrawal tunnel is connected to the energy dissipation pool, and two dams are set downstream of the energy dissipation pool to raise the water level. The two dams are connected to a downslope, the slope of the downslope is the slope of the riverbed itself, and then connected to a reverse slope guard, the reverse slope guard has a pick angle θ of 3° to 6°, the pick angle θ includes the endpoint value, and the slope of the reverse slope guard i 反坡 The slope is 1:10~1:15, and the slope is 反坡 Including the endpoint value, the drop height a of the reverse slope protection tank is lower than the maximum water depth downstream of the energy dissipation and flood prevention standard; the reverse slope protection tank is connected to the step section, the slope angle β of the step section is 5°~10°, the slope angle β includes the endpoint value, and the slope of the step surface i of the step section is 阶梯 The slope is 1:5~1:10, and the slope i 阶梯 Contains the endpoint value.

[0015] Furthermore, the step height d of each step of the step section is 1.0 to 1.5 m, and the step height d includes the endpoint value.

[0016] Furthermore, the drop height a of the anti-slope protection apron is 3 / 4 of the maximum water depth downstream of the energy dissipation and flood prevention standard.

[0017] Furthermore, the maximum downstream water depth of the energy dissipation and flood prevention standard is the maximum downstream water depth of a flood that returns once every 100 years.

[0018] Furthermore, the step section is provided with more than two steps, the step height of the highest step of the step section is calculated downward from the elevation of the top of the anti-slope protection tank, the step height of the second highest step is calculated downward from the bottom elevation of the highest step, and so on.

[0019] The present invention has the following beneficial effects:

[0020] The reverse slope guardrail of the present invention has a certain reverse slope. Compared with the horizontal guardrails in existing projects, the downstream water flow has a certain upward angle, so that the main stream can be located in the surface layer of the water depth downstream, preventing the main stream from sinking to the bottom and eroding the downstream riverbed; the various steps of the stage section connected after the reverse slope guardrail mainly play the role of a drop-off, and the drop-offs of each step of the step section are of different heights to adapt to the water level of different flow rates downstream.

[0021] A reverse slope protection tank is built at the end of the spillway structure, with the top elevation lower than the downstream tailwater level, and a stepped section adapted to different flow and water levels is connected behind the reverse slope protection tank. This is equivalent to designing a variety of drop-offs adapted to different flow and water levels. When rapids of different flow and water levels leave the reverse slope protection tank and the stepped section, they can all float on the surface, and energy is dissipated by diffusion over a longer distance and the coordination of the horizontal axis vortex at the bottom, and the scouring effect on the downstream riverbed is relatively light.

[0022] Specifically,

[0023] 1. This invention uses a reverse slope method, first descending and then ascending, to direct the discharge from the drainage structure to connect with the slow flow of the downstream natural river channel in a surface flow manner. The water forms a vortex between the surface water at the tail of the reverse slope apron and the riverbed, isolating the high-speed mainstream from the riverbed. The intense turbulent energy dissipation of the bottom vortex prevents the mainstream from directly contacting the riverbed, achieving the purpose of connection and energy dissipation. The downstream water flow is stable, which is conducive to the stability of the riverbed.

[0024] 2. The design of each step of the rear step section of the reverse slope protection tank of the present invention not only plays the role of drop flow energy dissipation, but also plays the role of reducing the drop height and connecting with the downstream water surface flow, and has strong adaptability to changes in downstream water flow.

[0025] 3. The energy dissipation connection structure of the present invention is relatively simple, with small engineering workload and low investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation;

[0027] Figure 2 This is a schematic diagram of the operation of the energy dissipation connection structure connecting natural river channels based on surface flow energy dissipation when the discharge volume is large;

[0028] Figure 3 This is a schematic diagram of the operation of the energy dissipation connection structure connecting the natural river channel based on surface flow energy dissipation when the discharge volume is small;

[0029] Figure 4 This is a schematic diagram of the overall structure of the vertical shaft flood discharge tunnel flood discharge energy dissipation structure of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0031] See also Figures 1 to 3 , an energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation, including a reverse slope protection tank 61 located behind a discharge structure and a stepped section 62 connected to the reverse slope protection tank 61.

[0032] The energy dissipation connection structure of the natural river channel based on the surface flow energy dissipation is set at the outlet of the discharge structure. The water discharged from the discharge structure first passes through a downslope. The slope of the downslope is the slope of the riverbed itself, and descends with the slope of the natural river channel. It is followed by a reverse slope apron 61. The vertical surface of the reverse slope apron 61 is a triangle. The purpose of the reverse slope apron 61 is to lift the discharged water flow to a certain height and guide the water flow to the surface layer. The angle θ of the reverse slope apron 61 is 3°~6° (including the end point value), where the angle θ is the angle between the inclined surface of the reverse slope apron 61 and the horizontal plane. The slope of the reverse slope i 反坡 The drop height a of the reverse slope apron 61 is lower than the maximum water depth downstream of the energy dissipation and scouring flood prevention standard (i.e., a flood with a return period of 100 years). Preferably, the drop height a of the reverse slope apron 61 is 3 / 4 of the maximum water depth downstream of the energy dissipation and scouring flood prevention standard (i.e., a flood with a return period of 100 years). The drop height a of the reverse slope apron 61 is the difference between the top elevation and the bottom elevation of the reverse slope apron 61.

[0033] The reverse slope guard 61 is connected to the step section 62, and the slope angle β of the step section 62 is 8° to 12° (including the end value), wherein the slope angle β of the step section 62 is the angle between the inclined plane formed by each step angle of the step section 62 and the horizontal plane. 阶梯 The slope of step section 62 is relatively gentle, ensuring that the surface of step section 62 of counter-slope apron 61 easily forms a falling flow, rather than a sliding flow. The step height d of each step of step section 62 is 1.0 to 1.5 m (inclusive). The step height of the highest step of step section 62 is calculated downward from the top elevation of counter-slope apron 61, the step height of the next highest step is calculated downward from the bottom elevation of the highest step, and so on. The step length l = d / tanβ.

[0034] Water flows on a stepped structure can have two flow patterns: drop flow and glide flow. Drop flow dissipates energy well, has a high efficiency rate, and easily connects with the downstream water level to form a surface flow. By designing the slope angle, gradient, and step height of the step section, the ratio of step section 62 to the critical water depth hc, or hc / d, can be kept low while maintaining the flow rate per unit width. That is, hc / d < 0.8, allowing the flow in step section 62 to form a drop flow pattern.

[0035] In a certain pumped storage project, the project adopts a combined flood discharge method of vertical shaft-type spillway and flood discharge and hollowing hole.

[0036] Among them, see Figure 4The bottom of the vertical shaft spillway is connected to the energy dissipation shaft 2. The connection between the vertical shaft 1 and the energy dissipation shaft 2 is connected to the drainage tunnel 3, which is then connected to the energy dissipation pool 4. A secondary dam 5 is installed downstream of the energy dissipation pool 4 to raise the water level and weaken the scouring force of the flood on the river channel at the outlet of the energy dissipation pool 4. Due to the large single-width flow, the narrow downstream river channel, poor riverbed geological conditions, and high local drop, the secondary scouring after the secondary dam 5 and the connection with the downstream water level are still serious problems. The original downstream river channel has a terrain slope of about 3.5%. The large drop makes it difficult to connect the flood discharge structure with the water flow in the natural river channel.

[0037] After the second dam 5, the slope descends with the slope of the natural river channel, and then rises at a slope of 1:10 to form a reverse slope protection tank 61. The reverse slope protection tank 61 has a reverse angle of 6° relative to the bottom slope of the river channel. The height difference between the top elevation of the reverse slope protection tank 61 and the bottom elevation of the downstream natural river channel, that is, the drop height, is 2.60m. The reverse slope protection tank 61, which first descends and then rises, guides the discharge after the second dam 5 to connect with the slow flow of the downstream natural river channel in the form of surface flow.

[0038] The reverse slope protection tank 61 is followed by a step section 62, and the slope angle β of the step section 62 is 11.3°. Therefore, the slope i of the step surface of the step section 62 is 阶梯 The ratio is 1:5, the stair section 62 has two steps in total, the step height d of each step is 1.0m, and the step length is 5.0m.

[0039] When a large flow is discharged, i.e. a flow with a return period of 2000 to 100 years, the water depth downstream of the reverse slope protection tank 61 after the jump is greater than the water depth after the jump. Under large flow conditions, the outflow behind the reverse slope protection tank 61 connects with the water flow of the downstream natural river in the form of surface flow. For details, see Figure 2 When the discharge is relatively small, i.e., less than the 20-year return flow, the water flow behind the reverse slope protection apron 61 falls to the step surface of the step section 62. When the downstream water level exceeds the step surface water depth, the water flow on the step surface naturally forms a surface flow and connects with the water flow in the downstream natural river channel. For details, see Figure 3 The presence of the stepped surface not only dissipates energy from the falling water, but also reduces the height of the drop and connects it with the downstream surface flow. A simple energy dissipation design can adapt to varying water levels in the downstream river.

[0040] A stepped shape, i.e., a stage section, is adopted behind the surface flow drop, i.e., the reverse slope apron 61. On the basis of ensuring that the surface flow connection is formed by utilizing the drop of the reverse slope apron 61 during large flow, the working condition of small flow is also ensured. When the downstream water depth is relatively small, the water flows through the reverse slope apron 61 and then falls onto the steps of the stage section behind it. This is equivalent to lowering the height a of the surface flow drop (reverse slope apron 61) to a height a'. When the water flows fall to a certain step surface, the height a' of the drop behind the step surface can meet the condition that the downstream water depth ht>the water depth after the jump h", and the discharged water still connects with the water flow of the natural river channel in the form of surface flow.

[0041] The above description is only a specific embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation, characterized by: It includes the reverse slope apron behind the discharge structure and the stepped section connected to the reverse slope apron; the discharge structure is connected to a downslope, the slope of the downslope is the slope of the riverbed itself, followed by a reverse slope apron, the angle θ of the reverse slope apron is 3°~6°, the angle θ includes the endpoint value, and the slope of the reverse slope i 反坡 The slope is 1:10~1:15, and the slope is 反 The slope includes the endpoint value, and the drop height a of the reverse slope protection tank is lower than the maximum water depth downstream of the energy dissipation and flood prevention standard; the reverse slope protection tank is connected to the step section, and the step section includes more than one step. The slope angle β of the step section is 5°~10°, and the slope angle β includes the endpoint value. The slope i of the step surface of the step section 阶梯 The slope is 1:5~1:10, and the slope i 阶梯 Contains the endpoint value.

2. The energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation according to claim 1 is characterized by: The ratio of the step height d of each step in the step section to the relative critical water depth hc is less than 0.8, and the step height of the highest step in the step section is calculated downward from the elevation of the top of the anti-slope protection tank.

3. The energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation according to claim 1 is characterized by: The step height d of each step in the step section is 1.0 to 1.5 m, and the step height d includes the endpoint value. The step height of the highest step in the step section is calculated downward from the elevation of the top of the anti-slope protection tank.

4. The energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation according to claim 1 is characterized by: The drop height a of the anti-slope protection apron is 3 / 4 of the maximum water depth downstream of the energy dissipation and flood prevention standard.

5. The energy dissipation connection structure for connecting natural river channels based on surface flow energy dissipation according to claim 1 or 4, characterized in that: The maximum downstream water depth of the energy dissipation and flood prevention standard is the maximum downstream water depth of a flood that returns once every 100 years.

6. A vertical shaft flood discharge tunnel flood discharge energy dissipation structure, wherein the bottom of the vertical shaft of the vertical shaft flood discharge tunnel is connected to the energy dissipation well, the connection between the vertical shaft and the energy dissipation well is connected to the drainage tunnel, and the drainage tunnel is connected to the stilling pool, characterized in that: A second dam is set up downstream of the stilling pool to raise the water level. A downslope is connected behind the second dam. The downslope is the slope of the riverbed itself. A reverse slope apron is connected after the second dam. The angle of the reverse slope apron is 3° to 6°. The angle θ includes the endpoint value. The slope of the reverse slope apron is i 反坡 The slope is 1:10~1:15, and the slope is 反坡 Including the endpoint value, the drop height a of the reverse slope protection tank is lower than the maximum water depth downstream of the energy dissipation and flood prevention standard; the reverse slope protection tank is connected to the step section, the slope angle β of the step section is 5°~10°, the slope angle β includes the endpoint value, and the slope of the step surface i of the step section is 阶梯 The slope is 1:5~1:10, and the slope i 阶梯 Contains the endpoint value.

7. The vertical shaft flood discharge tunnel flood discharge and energy dissipation structure according to claim 6, characterized in that: The step height d of each step of the step section is 1.0 to 1.5 m, and the step height d includes the endpoint value.

8. The vertical shaft flood discharge tunnel flood discharge and energy dissipation structure according to claim 6, characterized in that: The drop height a of the anti-slope protection apron is 3 / 4 of the maximum water depth downstream of the energy dissipation and flood prevention standard.

9. The vertical shaft flood discharge tunnel flood discharge and energy dissipation structure according to claim 6 or 8, characterized in that: The maximum downstream water depth of the energy dissipation and flood prevention standard is the maximum downstream water depth of a flood that returns once every 100 years.

10. The vertical shaft flood discharge tunnel flood discharge and energy dissipation structure according to claim 6, characterized in that: The step section is provided with two or more steps, and the step height of the highest step of the step section is calculated downward from the elevation of the top of the anti-slope protection tank, the step height of the second highest step is calculated downward from the bottom elevation of the highest step, and so on.

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