A type of combined arrangement of a spillway tunnel and a stilling basin of a spillway

Abstract

The application discloses a kind of flood discharge tunnel and spillway stilling basin combined arrangement structure type, flood discharge tunnel stilling basin and spillway stilling basin are arranged adjacent, two stilling basins have height difference in vertical water flow direction;Flood discharge tunnel stilling basin is close to the bottom plate elevation of spillway stilling basin on one side wall top of spillway stilling basin, the height of one side wall of flood discharge tunnel stilling basin away from spillway stilling basin is greater than the height of one side wall close to spillway stilling basin;Spillway stilling basin is not provided with side wall on one side close to flood discharge tunnel stilling basin.Part of water flow in spillway stilling basin falls into flood discharge tunnel stilling basin and dissipates energy through not setting side wall, water flow in flood discharge tunnel stilling basin rolls back to spillway stilling basin and forms counter-current energy dissipation with water flow in spillway stilling basin.The application solves the problem of poor flow state, poor energy dissipation effect when sharing stilling basin, saves earthwork excavation and concrete quantity.

Description

Technical Field

[0001] This invention relates to the field of flood discharge and energy dissipation technology in water conservancy and hydropower projects, specifically to a structural type that combines a flood discharge tunnel and a spillway energy dissipation pool. Background Technology

[0002] In water conservancy and hydropower projects, the high-speed water flow discharged from spillway structures carries enormous kinetic energy. If this energy cannot be effectively dissipated, it will adversely affect the stability of the riverbed and the safety of the riverbanks downstream. To prevent the excess energy of the discharged water flow from severely eroding the downstream river channel and threatening the stability of the slopes and the safe operation of the structures themselves, specialized energy dissipation facilities are usually installed in the projects to dissipate or disperse the excess energy during the discharge process as much as possible. This aspect is also a core focus and technical challenge in the construction of water conservancy and hydropower projects; and the rationality of the layout of the spillway energy dissipation structure directly determines the stability of the downstream riverbed and the operational safety of the entire hydropower project. Currently, commonly used energy dissipation methods in engineering are mainly divided into three categories: bottom flow energy dissipation, jet flow energy dissipation, and surface flow energy dissipation. Among them, jet flow energy dissipation has a wide range of applications due to fewer applicable restrictions, but it has high requirements for the geological conditions of the downstream scour area. Bottom flow energy dissipation, as a conventional form of energy dissipation, creates a hydraulic jump in the downstream stilling basin by causing the discharged water flow to dissipate the remaining energy of the water flow through the swirling effect and strong turbulence generated by the hydraulic jump. It has the characteristics of stable flow into the stilling basin, high energy dissipation efficiency, and minimal impact from the discharged water mist.

[0003] In current pumped-storage power station construction, the upper reservoir often utilizes natural mountain passes, while the lower reservoir is typically a shore-side reservoir. These reservoirs lack natural runoff and have relatively small catchment areas. Therefore, compared to conventional water conservancy and hydropower projects, pumped-storage power stations have smaller flood discharge capacities. However, the construction of pumped-storage power stations is highly sensitive to project cost indicators. Combining the energy dissipation structures of the spillway and flood discharge tunnel can effectively reduce excavation, steel reinforcement, and concrete usage, thus optimizing project investment.

[0004] However, the existing combined layout of spillway and stilling basin structures still has many limitations. Especially in scenarios with limited terrain, it's difficult for the spillway and spillway axes to form a proper angle, preventing the water flow from effectively dissipating energy. Furthermore, when stilling basins are combined, auxiliary energy dissipation structures such as stilling blocks and stilling teeth are often placed within the basins to improve energy dissipation efficiency. During operation, these auxiliary structures are frequently damaged by impacts from floating debris and boulders, increasing operational difficulty and maintenance pressure. When the spillway and spillway axes are arranged parallel, the inflow rates usually differ significantly, easily leading to water rotation problems within the stilling basin. This results in a large difference in water surface area on both sides of the basin, poor flow patterns, and ineffective energy dissipation. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention discloses a combined arrangement of a flood discharge tunnel and a stilling basin for a spillway, in order to solve the problems of prominent water flow rotation, poor flow pattern, and poor energy dissipation effect when the flood discharge tunnel and the spillway share a stilling basin.

[0006] The technical solution adopted in this invention is a combined arrangement of a flood discharge tunnel and a spillway stilling basin, including a flood discharge tunnel outlet diffusion section, a flood discharge tunnel stilling basin, a side wall of the flood discharge tunnel stilling basin, a tail sill of the flood discharge tunnel, a spillway stilling basin, and a spillway stilling basin and a side wall of the spillway stilling basin. The flood discharge tunnel stilling basin and the spillway stilling basin are arranged adjacent to each other, and the two stilling basins have a height difference in the direction perpendicular to the water flow. The top of the side wall of the flood discharge tunnel stilling basin near the spillway stilling basin is at the same elevation as the bottom plate of the spillway stilling basin, and the height of the side wall of the flood discharge tunnel stilling basin away from the spillway stilling basin is greater than the height of the side wall of the side wall near the spillway stilling basin. No side wall is set on the side of the spillway stilling basin near the flood discharge tunnel stilling basin. Part of the water flow in the spillway stilling basin falls into the flood discharge tunnel stilling basin through the side without a side wall to dissipate energy, and the water flow in the flood discharge tunnel stilling basin rolls back into the spillway stilling basin, forming a counter-current energy dissipation with the water flow in the spillway stilling basin.

[0007] Furthermore, the axis of the spillway and the axis of the flood discharge tunnel are arranged parallel to each other or intersect at a small angle.

[0008] Furthermore, the diffusion angle of the diffusion section at the outlet of the flood discharge tunnel is 10°~20°, and the length of the diffusion section is 15~40m.

[0009] Furthermore, the stilling basin of the flood discharge tunnel is an excavated stilling basin with a depth of 3-8m, a width of 10-20m, and a length of 20-50m.

[0010] Furthermore, the stilling basin of the flood discharge tunnel is provided with a tail sill at its end. The top width of the tail sill is 1m, the bottom width is 3~5m, and the height of the tail sill is the same as the depth of the stilling basin of the flood discharge tunnel.

[0011] Furthermore, the slope ratio of the tail sill is 1:0.5.

[0012] Furthermore, the spillway stilling basin is a flat-bottomed stilling basin, and the bottom elevation of the spillway stilling basin is higher than that of the flood discharge tunnel stilling basin; the width of the spillway stilling basin is 5~10m, and the length is 20~50m.

[0013] Furthermore, the side wall of the stilling basin of the flood discharge tunnel near the stilling basin of the spillway is a counterweight retaining wall.

[0014] Furthermore, the top elevation of the side wall of the stilling basin of the spillway away from the stilling basin of the flood discharge tunnel is not lower than the top elevation of the side wall of the stilling basin of the flood discharge tunnel away from the stilling basin of the spillway.

[0015] Furthermore, the stilling basin of the flood discharge tunnel and the diffusion section at the outlet of the flood discharge tunnel are arranged along the same axis.

[0016] The technical solution adopted in this invention can achieve the following beneficial effects: by arranging the stilling basin of the spillway tunnel and the stilling basin of the flood discharge tunnel adjacent to each other, and without setting a retaining wall on the side of the stilling basin of the flood discharge tunnel, the bottom plate of the stilling basin of the flood discharge tunnel is higher than the bottom plate of the stilling basin of the spillway tunnel, so that the water flow in the flood discharge tunnel can fall into the stilling basin of the spillway tunnel for energy dissipation; the turbulent water flow formed after the hydraulic jump in the stilling basin of the spillway tunnel can flow back to the stilling basin of the flood discharge tunnel to form counter-current energy dissipation, which can improve the energy dissipation efficiency in a compact and simple arrangement, and avoid the problem that when the spillway tunnel and the flood discharge tunnel directly use the same stilling basin, the water flow in the basin rotates, the flow state is poor, and the energy dissipation effect is poor. Attached Figure Description

[0017] Figure 1 This is a top view of the combined arrangement of the spillway tunnel and the stilling basin disclosed in this embodiment of the invention; Figure 2 This is a longitudinal sectional view of the stilling basin of the spillway tunnel in an embodiment of the present invention; Figure 3 This is a longitudinal sectional view of the stilling basin of the spillway in an embodiment of the present invention; Figure 4 This is a cross-sectional view of the combined arrangement structure of the stilling pools in an embodiment of the present invention.

[0018] In the diagram, 1—diffusion section of the spillway; 2—stilling basin of the spillway; 3—side wall of the stilling basin of the spillway away from the spillway; 4—tail sill of the stilling basin of the spillway; 5—stilling basin of the spillway; 6—side wall of the stilling basin of the spillway; 7—side wall of the stilling basin of the spillway near the spillway. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] In the description of this invention, it should be noted that the terms "upper", "middle", "lower", "inner", "outer", "both sides", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this invention and do not indicate or imply that the structure referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] like Figures 1 to 4As shown, the combined arrangement of the flood discharge tunnel and the stilling basin provided by the present invention includes a flood discharge tunnel outlet diffusion section 1, a flood discharge tunnel stilling basin 2, a flood discharge tunnel sidewall, a flood discharge tunnel tail sill 4, a stilling basin of the spillway 5, and a stilling basin sidewall of the spillway 6.

[0022] The stilling basin 2 of the spillway and the stilling basin 5 of the flood discharge tunnel are arranged adjacent to each other, with a height difference between them in the direction perpendicular to the water flow. The stilling basin 2 of the spillway adopts an excavated structure, and the top of its sidewall 7 on the side closest to the stilling basin 5 of the flood discharge tunnel is at the same elevation as the bottom slab of the stilling basin 5, that is, the top surface of the sidewall 7 is flush with the bottom slab of the stilling basin 5 of the flood discharge tunnel. The height of the sidewall 3 of the stilling basin 2 on the side away from the stilling basin 5 of the spillway is greater than the height of the sidewall 7 on the side closest to the stilling basin 5 of the flood discharge tunnel. The side of the stilling basin 5 of the flood discharge tunnel that is closest to the stilling basin 2 of the spillway has no sidewall, so that the two stilling basins are interconnected on this side.

[0023] During flood discharge, the high-speed water flow from the spillway enters the stilling basin 2 of the spillway through the outlet diffusion section 1. A submerged hydraulic jump is formed within the stilling basin 2, where most of the energy is dissipated through the swirling and turbulent mixing effects. Simultaneously, the water flow from the spillway enters the stilling basin 5 of the spillway. Since the bottom elevation of the stilling basin 5 is higher than that of the stilling basin 2 of the spillway, and there is no sidewall obstructing the flow on the side of the stilling basin 5 closest to the stilling basin 2, some of the water in the stilling basin 5 falls into the lower stilling basin 2 of the spillway under the influence of gravity, further dissipating energy during the fall. After a hydraulic jump, the turbulent water flow in the stilling basin 2 of the spillway is fully turbulent. Some of the water flow after the jump rolls back into the stilling basin 5 of the spillway through the top of the side wall 7 on the side of the stilling basin near the spillway. It then forms a head-on collision with the downstream water flow in the stilling basin 5 of the spillway. During the collision and mixing of the water flows, the remaining energy is further dissipated.

[0024] By arranging the stilling basin 2 of the spillway tunnel and the stilling basin 5 of the flood discharge tunnel adjacent to each other with a height difference, and utilizing the structure of the stilling basin 5 without a sidewall on the side closest to the stilling basin 2 of the spillway tunnel, a dual interactive mechanism of "falling in for energy dissipation + backflow counter-current for energy dissipation" is formed in the water flow within the two stilling basins. This structure effectively avoids problems such as water flow rotation, large water surface differences on both sides, poor flow patterns, and poor energy dissipation effects that occur when the spillway tunnel and the flood discharge tunnel directly share the same stilling basin, significantly improving energy dissipation efficiency. Simultaneously, this arrangement eliminates the need for auxiliary energy dissipation structures such as stilling blocks and stilling teeth within the stilling basin, avoiding the risk of damage caused by floating objects and rock impacts, and reducing the difficulty and cost of operation and maintenance. Furthermore, the combined arrangement of the two stilling basins effectively reduces the amount of earthwork excavation, steel reinforcement, and concrete used, making it particularly suitable for engineering scenarios where terrain conditions are limited and it is impossible to arrange two stilling basins separately.

[0025] Furthermore, the axis of the spillway and the axis of the flood discharge tunnel are arranged in parallel or intersect at a small angle.

[0026] In water conservancy and hydropower projects, when the terrain conditions are limited, it is often difficult to form a large angle between the axis of the spillway and the axis of the flood discharge tunnel to facilitate the counterflow of water. This technical solution adopts a parallel arrangement or a small-angle intersection arrangement of the axis of the spillway and the axis of the flood discharge tunnel, so that the two stilling basins can be set up side by side along the direction of water flow, achieving a combined arrangement without increasing the land area.

[0027] The parallel or small-angle (no more than 3°) intersection of the spillway and floodgate axes means that the outlet water flow directions of the two structures are basically the same or the included angle is small. Under this condition, the two stilling basins can be arranged parallel to each other along the axis direction, with a shared sidewall 7 separating the basins. The arrangement of parallel or small-angle intersection of axes ensures that the inflow direction of the stilling basin is basically consistent with the axis direction of the stilling basin, and the water flow can spread smoothly after entering the stilling basin, which is conducive to the formation of a stable hydraulic jump. This breaks through the limitation of traditional energy dissipation structures requiring the spillway and floodgate axes to form a certain angle to achieve water flow counterflow. It enables efficient energy dissipation through the combined arrangement structure of this invention in engineering scenarios where terrain conditions are limited and the axes of the two spillway structures cannot form a large-angle intersection for counterflow energy dissipation, significantly broadening the scope of application of this invention.

[0028] Furthermore, the diffusion angle of the diffusion section 1 at the outlet of the flood discharge tunnel is 10°~20°, and the length of the diffusion section is 15~40m.

[0029] The outlet diffusion section 1 of the spillway gradually widens along the flow direction. The angle formed by the outward expansion of its two sidewalls is the diffusion angle. This technical solution sets the diffusion angle to 10°~20° and the length of the diffusion section to 15~40m. The flow velocity and unit width flow rate at the spillway outlet are relatively high. If the water flows directly into the stilling basin without diffusion, the inflow will be too concentrated, making it difficult to form an effective hydraulic jump within the stilling basin. By setting the outlet diffusion section 1 with a diffusion angle of 10°~20°, the downstream flow gradually diffuses along the width direction within the diffusion section, the cross-sectional area of ​​the flow gradually increases, and the flow velocity and unit width flow rate decrease accordingly. The diffusion section length of 15~40m provides sufficient diffusion distance, ensuring that the water flow is fully diffused before entering the stilling basin 2 of the spillway, resulting in a more uniform flow pattern. By rationally controlling the diffusion angle and diffusion section length, the unit width flow rate and velocity of the water flow at the outlet of the flood discharge tunnel are effectively reduced, the impact force of the water flow on the bottom plate of the stilling basin is reduced, which is conducive to shortening the length and reducing the depth of the stilling basin, thereby saving project investment.

[0030] Furthermore, the stilling basin 2 of the flood discharge tunnel adopts a dug stilling basin with a depth of 3~8m, a width of 10~20m, and a length of 20~50m.

[0031] A down-drained stilling basin refers to a stilling basin structure formed by excavating the bottom of the stilling basin downwards when its bottom elevation is lower than that of the outlet bottom of the spillway. This technical solution sets the spillway stilling basin 2 as a down-drained structure, with a depth ranging from 3 to 8 meters, a width ranging from 10 to 20 meters, and a length ranging from 20 to 50 meters. When the high-speed water flow from the spillway enters the down-drained stilling basin 2, the water flow suddenly expands and drops upon entering the stilling basin because its bottom is lower than the outlet bottom, forming a submerged hydraulic jump within the basin. During the hydraulic jump, strong swirling and turbulent mixing occur within the water flow. Through the mutual friction, collision, and mixing between the particles within the water flow, the macroscopic kinetic energy of the water flow is converted into microscopic heat energy dissipation. The basin depth of 3 to 8 meters ensures sufficient tailrace depth within the stilling basin, allowing the hydraulic jump to be stably submerged below the water surface, avoiding unfavorable flow patterns such as long-range hydraulic jumps or wavy hydraulic jumps. The pool width of 10-20m matches the width of the diffuser section, ensuring a uniform distribution of the incoming water flow across its width. The pool length of 20-50m provides sufficient space for the full development of the hydraulic jump, ensuring that the water completes its primary energy dissipation process before exiting the stilling basin. The excavated stilling basin has a simple structure and is easy to construct. By rationally setting the pool depth, width, and length parameters, a stable submerged hydraulic jump is formed within the stilling basin, ensuring high energy dissipation efficiency and stable flow, while avoiding the use of complex auxiliary energy dissipation structures.

[0032] Furthermore, a tail sill 4 is provided at the end of the stilling basin 2 of the flood discharge tunnel. The top width of the tail sill 4 is 1m, the bottom width is 3~5m, and the height of the tail sill 4 is the same as the depth of the stilling basin 2 of the flood discharge tunnel.

[0033] The tail sill 4 is a raised structure located at the end of the stilling basin, spanning the entire width of the basin. Its cross-section is trapezoidal, with a top width of 1m and a bottom width of 3-5m. Its height is the same as the depth of the stilling basin 2. The tail sill 4 is positioned at the end of the stilling basin 2 to raise the water level. When water flows from the stilling basin 2 to the tail sill 4, the water depth is raised due to the tail sill 4's water-blocking effect, creating a sufficient tailwater depth to ensure the hydraulic jump remains submerged. The 1m width at the top of the tail sill 4 provides sufficient flow width, allowing water to smoothly overturn the tail sill 4 and enter the downstream channel. The 3-5m width at the bottom ensures the structural stability of the tail sill 4, preventing overturning or sliding under long-term water flow impact. The height of the tail sill 4 is the same as the basin depth, ensuring the backwater height matches the design water depth of the stilling basin, keeping the hydraulic jump stable in the middle or front of the stilling basin, and preventing the hydraulic jump from being pushed out of the stilling basin. The tail sill 4 is simple and reliable to set up. It can effectively increase the water depth in the stilling basin, promote and stabilize the submerged hydraulic jump, and ensure that the stilling basin can maintain a good energy dissipation flow state under various working conditions. In addition, the trapezoidal cross section of the tail sill 4 has reasonable stress distribution and good impact resistance and wear resistance.

[0034] Furthermore, the slope ratio of the tail sill 4 is 1:0.5.

[0035] The slope of tail sill 4 refers to the water-facing side of tail sill 4 facing the stilling basin, with a slope ratio of 1:0.5, meaning the ratio of vertical height to horizontal width is 1:0.5. This slope gradually slopes upwards from the bottom of tail sill 4 towards the stilling basin. When the post-jump water flow in the stilling basin 2 of the spillway flows over tail sill 4, the 1:0.5 slope allows the water to climb smoothly along the slope, avoiding violent impacts and localized hydraulic jumps on the water-facing side of tail sill 4, thus reducing the impact force of the water flow on tail sill 4. The slope guides the water flow smoothly over the top of tail sill 4, maintaining a good flow pattern during the overpass and avoiding the formation of backflow or vortex zones downstream of tail sill 4.

[0036] By optimizing the slope ratio of the tail sill 4, the local flow pattern at the tail sill 4 was improved, the impact and damage of the water flow on the tail sill 4 were reduced, and the smooth connection after the water flow crosses the tail sill 4 was ensured.

[0037] Furthermore, the stilling basin 5 of the spillway is a flat-bottomed stilling basin, and the bottom elevation of the stilling basin 5 of the spillway is higher than the bottom elevation of the stilling basin 2 of the flood discharge tunnel; the width of the stilling basin 5 of the spillway is 5~10m and the length is 20~50m.

[0038] A flat-bottomed stilling basin refers to a stilling basin with a horizontal bottom slab whose elevation is basically the same as that of the spillway outlet stilling basin. The bottom elevation of the spillway stilling basin 5 is higher than that of the flood discharge tunnel stilling basin 2, creating a height difference between them. The width of the spillway stilling basin 5 ranges from 5 to 10 meters, and its length ranges from 20 to 50 meters. After the water discharged from the spillway enters the flat-bottomed stilling basin 5, the flat bottom structure causes a certain degree of swirling and turbulence within the stilling basin, achieving initial energy dissipation. Since the bottom elevation of the spillway stilling basin 5 is higher than that of the flood discharge tunnel stilling basin 2, and there is no sidewall obstruction on the side of the spillway stilling basin 5 closest to the flood discharge tunnel stilling basin 2, some of the water in the spillway stilling basin 5 falls into the lower-level flood discharge tunnel stilling basin 2 under the influence of gravity, further dissipating energy during the fall. Meanwhile, the tumbling water flow in the stilling basin 2 of the spillway flows back through the top of the sidewall 7 to the stilling basin 5 of the overflow channel, creating a countercurrent with the water flow in the stilling basin 5 that has not yet fallen into the stilling basin 2 of the spillway. The basin width of 5-10m matches the width of the overflow channel outlet, and the basin length of 20-50m provides sufficient space for the initial energy dissipation of the water flow in the stilling basin 5 of the overflow channel. The stilling basin 5 of the overflow channel adopts a flat-bottomed structure, which is simple to construct and has a low cost. The structural design that the bottom elevation of the stilling basin 5 of the overflow channel is higher than that of the stilling basin 2 of the spillway is not only a prerequisite for realizing the function of "the water flow of the overflow channel falling into the stilling basin of the spillway", but also the key to realizing the interaction and countercurrent energy dissipation of the water flow in the two basins. This significantly improves the energy dissipation effect of the stilling basin 5 of the overflow channel, enabling the overflow channel to achieve efficient energy dissipation even without the installation of auxiliary energy dissipation works.

[0039] Furthermore, the side wall 7 of the stilling basin 2 of the flood discharge tunnel, which is close to the stilling basin of the spillway, is a counterweight retaining wall.

[0040] A counterweight retaining wall is a retaining wall structure that relies on its own weight and the weight of the backfill on a counterweight platform to resist earth pressure. Its cross-sectional characteristics include a counterweight platform on the back of the wall, and a trapezoidal or stepped cross-section that is smaller at the top and larger at the bottom. Side wall 7 serves both as a side wall of the spillway stilling basin 2 and as a structure separating the two stilling basins, needing to withstand both the water pressure inside the spillway stilling basin 2 and the earth pressure on one side of the overflow stilling basin 5. Employing a counterweight retaining wall structure, side wall 7 provides sufficient anti-sliding and anti-overturning stability due to its large cross-sectional dimensions and weight. The top of side wall 7 is at the same elevation as the bottom slab of the overflow stilling basin 5, making the top of side wall 7 part of the bottom slab of the overflow stilling basin 5, while the lower part of side wall 7 acts as a side wall of the spillway stilling basin 2, constraining the water flow within the basin. The stepped cross-section of the counterweight retaining wall provides a natural supporting foundation for the bottom slab of the overflow stilling basin 5. The counterweight retaining wall structure is stable, has strong anti-sliding and anti-overturning capabilities, and can simultaneously meet the functional requirements of separating two stilling basins and bearing water pressure and soil pressure on both sides. It is also convenient and economical to construct.

[0041] Furthermore, the top elevation of the sidewall 6 on the side of the spillway stilling basin 5 away from the stilling basin 2 of the flood discharge tunnel is not lower than the top elevation of the sidewall 3 on the side of the stilling basin 2 of the flood discharge tunnel away from the stilling basin 5 of the spillway.

[0042] Sidewall 6 is a water-retaining structure outside the stilling basin 5 of the spillway, and its top elevation is not lower than the top elevation of the sidewall 3 outside the stilling basin 2 of the flood discharge tunnel.

[0043] During the collision process between the water flow in the stilling basin 5 of the spillway and the water returning from the stilling basin 2 of the flood discharge tunnel to the stilling basin 5, local water level rises may occur. If the top elevation of the sidewall 6 is too low, the water flow may overflow the sidewall 6, causing damage to the buildings or slopes outside the stilling basin. The top elevation of the sidewall 6 is set to be no lower than the top elevation of the sidewall 3 to ensure that the sidewall 6 has sufficient water-retaining height to restrain all the water flow in the stilling basin 5 of the spillway and prevent the water flow from overflowing the stilling basin during turbulence and collision.

[0044] By setting the top elevation of the sidewall 6, the stilling basin 5 of the spillway has sufficient water-blocking height under various operating conditions, avoiding water overflow and safety accidents, and improving the safety and reliability of the structure.

[0045] Furthermore, the stilling basin 2 of the flood discharge tunnel and the diffusion section 1 of the flood discharge tunnel outlet are arranged on the same axis.

[0046] The centerline of the outlet diffusion section 1 of the spillway and the centerline of the stilling basin 2 of the spillway are on the same straight line, and their axes coincide. After the water flowing down the spillway diffuses through the outlet diffusion section 1, it enters the stilling basin 2. The coaxial arrangement of the diffusion section and the stilling basin ensures that the water flow remains symmetrical along the centerline during diffusion and entry into the stilling basin, resulting in uniform water diffusion and a balanced flow distribution across the width of the stilling basin. This is conducive to forming a symmetrical and stable hydraulic jump within the stilling basin. If the axes of the diffusion section and the stilling basin are misaligned, the incoming water flow will be biased to one side, leading to asymmetrical flow patterns on both sides of the stilling basin. One side will have concentrated flow, while the other side will form a backflow zone, severely affecting the energy dissipation effect. The coaxial arrangement ensures a smooth and symmetrical incoming water flow, which is conducive to forming a stable submerged hydraulic jump within the stilling basin 2 of the spillway, improving energy dissipation efficiency and the stability of the flow pattern.

[0047] The overall working principle of the combined layout of the spillway tunnel and the stilling basin provided by this invention is as follows: During flood discharge, the high-speed water flow from the flood discharge tunnel first passes through the outlet diffuser section 1. Within the diffuser section, the water flow gradually spreads along its width, reducing its velocity and unit width flow rate. The water then enters the stilling basin 2 of the excavated flood discharge tunnel. Because the basin bottom is lower than the outlet floor slab, the water flow forms a submerged hydraulic jump within the basin. Most of the energy is dissipated through the intense swirling and turbulent mixing of the hydraulic jump. The tailrace sill 4 at the end of the stilling basin 2 raises the water depth, providing sufficient tailrace depth for the stability of the hydraulic jump.

[0048] Simultaneously, the water flowing down the spillway enters the flat-bottomed stilling basin 5, where initial energy dissipation occurs. Since the bottom elevation of the stilling basin 5 is higher than that of the stilling basin 2 of the flood discharge tunnel, and the side of the stilling basin 5 closest to the flood discharge tunnel stilling basin 2 lacks a sidewall, some of the water in the stilling basin 5 falls into the lower-level stilling basin 2 of the flood discharge tunnel under gravity, achieving secondary energy dissipation during the fall. A portion of the turbulent water flow that forms after the hydraulic jump in the stilling basin 2 flows back into the stilling basin 5 through the top of the sidewall 7 near the stilling basin 5, creating a head-on collision with the water flowing down the stilling basin 5. The collision and mixing of the water further dissipates the remaining energy.

[0049] Through the synergistic effect of the aforementioned triple energy dissipation mechanism of "hydraulic jump energy dissipation - drop energy dissipation - counter-current energy dissipation," the enormous kinetic energy of the water flowing down the spillway and floodgate is efficiently dissipated. Although the two stilling basins are arranged adjacent to each other, the height control of the sidewall 7 and the structural design of not having a sidewall on one side of the stilling basin 5 in the spillway ensure that the two stilling basins have both their own independence (each forming basic hydraulic jump or turbulent energy dissipation) and close water flow interaction (drop and counter-current). This avoids the problems that are prone to occur when two structures directly share the same stilling basin, such as water flow rotation, large water surface difference on both sides, and turbulent flow, thus achieving efficient and stable energy dissipation under compact arrangement conditions.

[0050] This invention, through the adjacent arrangement of the spillway stilling basin 2 and the overflow stilling basin 5 with a height difference perpendicular to the water flow direction, and in conjunction with the structural design where the top of the sidewall 7 of the spillway stilling basin 2 near the overflow stilling basin 5 is at the same elevation as the bottom plate of the overflow stilling basin 5, and the sidewall of the overflow stilling basin 5 near the spillway stilling basin 2 is not provided, achieves a dual interactive energy dissipation mechanism of "overflow from the overflow stilling basin falling into the spillway stilling basin" and "water flowing back from the spillway stilling basin to the overflow stilling basin to form a countercurrent," significantly improving the overall energy dissipation efficiency of the combined arrangement structure. Engineering practice has verified that this structural design has good energy dissipation effect, with stable water flow within the stilling basins, and no unfavorable flow conditions such as water rotation or large water level differences on both sides.

[0051] This invention effectively solves the prominent problems of severe water flow rotation, poor flow pattern, and poor energy dissipation effect in traditional shared stilling basin schemes when the axes of the spillway and the flood discharge tunnel are parallel or intersect at a small angle, and the terrain conditions limit the arrangement of two stilling basins. This invention does not rely on the angle between the axes of the two structures to achieve water flow counterflow, and has a wider range of applications.

[0052] This invention eliminates the need for auxiliary energy dissipation devices such as energy dissipation blocks and energy dissipation teeth in the stilling pool. It achieves efficient energy dissipation entirely through the interaction between the pool structure and the water flow itself, fundamentally avoiding structural damage caused by floating objects and boulders impacting the auxiliary energy dissipation devices during operation, and significantly reducing the difficulty and cost of operation and maintenance.

[0053] This invention, by merging two stilling basins, significantly reduces the amount of earthwork excavation, steel reinforcement, and concrete pouring compared to arranging two stilling basins separately, effectively lowering project costs. It is particularly suitable for pumped storage power stations and other projects where cost is a significant factor. Preliminary estimates suggest that this invention can save approximately 20% to 30% of project investment compared to arranging two stilling basins separately.

[0054] The present invention has a simple structure and is easy to construct. All components—the flood discharge tunnel outlet diffusion section 1, the flood discharge tunnel stilling basin 2, the side walls 3 and 7, the tail sill 4, the spillway stilling basin 5, and the side walls 6—are conventional hydraulic structures. The construction technology is mature, the quality is easy to control, and it has good engineering promotion value.

[0055] Example A certain project adopted the combined layout structure of the flood discharge tunnel and the stilling basin of the spillway of the present invention. The combined layout structure includes the outlet diffusion section of the flood discharge tunnel, the stilling basin of the flood discharge tunnel, the side walls and the tail sill, and the stilling basin and side walls of the spillway.

[0056] The diffusion angle of the spillway's diffusion section is 15.65°, the width at the beginning of the diffusion section is 3m, the width at the end is 14m, and the length of the diffusion section is 19.6m. The diffusion section reduces the unit width flow rate and velocity of the water flow at the spillway outlet.

[0057] The stilling basin of the spillway is an excavated stilling basin, which is 35m long, 14m wide and 5m deep. The bottom elevation of the stilling basin is 549.00m. The spillway and the stilling basin are coaxial to ensure smooth water flow into the basin.

[0058] The stilling basin of the spillway is equipped with a counterweight retaining wall on the side closest to the spillway. The retaining wall is 7m high, 1m wide at the top, and has a top elevation of 556.00m. It is used to separate the stilling basin of the spillway from the stilling basin and raise the bottom elevation of the stilling basin of the spillway. The stilling basin of the spillway away from the spillway has a retaining wall 11m high, 1m wide at the top, and has a top elevation of 560.00m. It is used to restrain the water flow in the basin and prevent the water from overflowing the stilling basin after the spillway.

[0059] The end sill of the stilling basin of the spillway is 5m high, 1m wide at the top, and 3.5m wide at the bottom. The slope ratio of the sill is 1:0.5. The sill increases the water depth in the stilling basin, which promotes and stabilizes the submerged hydraulic jump.

[0060] The stilling basin of the spillway is flat-bottomed, 35m long, 7m wide, and with a bottom elevation of 556.00m. The centerline of the stilling basin is 1m away from the axis of the spillway, allowing the incoming water to diffuse towards the spillway tunnel side, with some water falling into the spillway tunnel's stilling basin for energy dissipation. The stilling basin of the spillway is 7m higher than the stilling basin of the main spillway. Some of the water that has jumped in the spillway tunnel's stilling basin swirls back into the stilling basin of the spillway, counteracting the outflow from the stilling basin and improving energy dissipation efficiency.

[0061] The stilling basin of the spillway does not have a retaining wall on the side near the spillway, while the retaining wall on the side away from the spillway is 4m high, 1m wide at the top, and 560.00m high at the top, in order to prevent water from overflowing the stilling basin from the spillway.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A combined arrangement of a flood discharge tunnel and a stilling basin in a spillway, comprising a flood discharge tunnel outlet diffusion section (1), a flood discharge tunnel stilling basin (2), a side wall of the flood discharge tunnel stilling basin, a tail sill of the flood discharge tunnel (4), a stilling basin in a spillway (5), and a side wall of the stilling basin in a spillway, characterized in that, The flood discharge tunnel stilling basin (2) and the spillway stilling basin (5) are arranged adjacent to each other, and the two stilling basins have a height difference in the direction of vertical water flow. The top of the side wall of the flood discharge tunnel stilling basin (2) near the spillway stilling basin is at the same elevation as the bottom plate of the spillway stilling basin (5). The height of the side wall of the flood discharge tunnel stilling basin (2) away from the spillway stilling basin is greater than the height of the side wall near the spillway stilling basin. The side wall of the spillway stilling basin (5) near the flood discharge tunnel stilling basin (2) is not provided. Part of the water flow in the spillway stilling basin (5) falls into the flood discharge tunnel stilling basin (2) through the side without a side wall to dissipate energy. The water flow in the flood discharge tunnel stilling basin (2) rolls back into the spillway stilling basin (5) and forms a counter-current energy dissipation with the water flow in the spillway stilling basin (5).

2. The combined arrangement of the spillway tunnel and stilling basin according to claim 1, characterized in that, The axis of the spillway tunnel and the axis of the overflow channel are arranged parallel to each other or intersect at a small angle.

3. The combined arrangement of the spillway tunnel and the stilling basin according to claim 1, characterized in that, The diffusion angle of the diffusion section (1) at the outlet of the flood discharge tunnel is 10°~20° and the length of the diffusion section is 15~40m.

4. The combined arrangement of the spillway tunnel and the stilling basin according to claim 1, characterized in that, The stilling basin (2) of the flood discharge tunnel is an excavated stilling basin with a depth of 3~8m, a width of 10~20m, and a length of 20~50m.

5. The combined arrangement of the spillway tunnel and the stilling basin according to claim 4, characterized in that, The end of the stilling basin (2) of the flood discharge tunnel is provided with a tail sill (4). The top width of the tail sill (4) is 1m and the bottom width is 3~5m. The height of the tail sill (4) is the same as the depth of the stilling basin (2) of the flood discharge tunnel.

6. The combined arrangement of the spillway tunnel and the stilling basin according to claim 5, characterized in that, The slope ratio of the tail sill (4) is 1:0.

5.

7. The combined arrangement of the spillway tunnel and stilling basin according to claim 1, characterized in that, The spillway stilling basin (5) is a flat-bottomed stilling basin. The bottom elevation of the spillway stilling basin (5) is higher than that of the stilling basin (2) of the flood discharge tunnel. The width of the spillway stilling basin (5) is 5~10m and the length is 20~50m.

8. The combined arrangement of the spillway tunnel and stilling basin according to claim 1, characterized in that, The side wall of the stilling basin (2) of the flood discharge tunnel, which is close to the stilling basin (5) of the spillway, is a counterweight retaining wall.

9. The combined arrangement of the spillway tunnel and the stilling basin according to claim 1, characterized in that, The top elevation of the side wall of the spillway stilling basin (5) away from the flood discharge tunnel stilling basin (2) shall not be lower than the top elevation of the side wall of the flood discharge tunnel stilling basin (2) away from the spillway stilling basin (5).

10. The combined arrangement of the spillway tunnel and stilling basin according to claim 1, characterized in that, The stilling basin (2) of the flood discharge tunnel is arranged along the same axis as the diffusion section (1) at the outlet of the flood discharge tunnel.

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