Spillway for dissipating energy by utilizing surface overflow of rock mountain

Abstract

The utility model provides a spillway for dissipating energy by utilizing rock surface overflow, and relates to the technical field of spillways. The device comprises an approach channel section, an overflow weir, a discharge chute and a middle stilling pool which are sequentially arranged in the elevation descending direction, a widened side weir is arranged on the side, close to a river, of the middle stilling pool and connected with the surface of a rock mountain, guide walls are arranged on the left side and the right side of the surface of the rock mountain, and the bottom of the surface of the rock mountain is connected with an apron; water flow is introduced into the middle stilling pool through the discharge chute for primary energy dissipation and then overflows to the surface of the rock mountain through the widened side weir on the outer side of the middle stilling pool for overflowing, and energy dissipation is accelerated by changing the flow direction and the flow state of the water flow, reducing the depth of the water flow and fully aerating the water flow on the uneven surface of the rock mountain.

Description

Technical Field

[0001] The utility model relates to the technical field of spillways, in particular to a spillway which utilizes rock surface overflow to dissipate energy. Background Art

[0002] Spillways are drainage structures within reservoirs and other water conservancy projects. They are used to discharge floodwaters that cannot be accommodated by the planned storage capacity, prevent floodwaters from overflowing the dam crest, and ensure dam safety. Spillways typically consist of four main components: a diversion section, a control section, a chute section, and an energy dissipator. Commonly used energy dissipators include twisted sills, inclined sills, and narrow slit sills. These dissipators are characterized by forcing the concentrated energy of the water flow to diffuse longitudinally, laterally, and vertically, and to impact the water streams, promoting turbulent aeration and expanding the jet inflow area to achieve the desired energy dissipation effect. However, this also introduces problems such as atomization.

[0003] In high and steep mountainous areas, where geological conditions are often favorable and the mountain's surface cover is exposed, the end of a conventional spillway chute must connect to the riverbed downstream of the dam. The length and slope of the spillway chute are determined by the topographical and geological conditions. Floodwaters are concentrated through the chute, reaching the riverbed elevation at the chute outlet. The water velocity is high, the energy is concentrated, and the destructive force is significant. Therefore, a large energy dissipator is generally required at the spillway outlet to effectively dissipate the high-speed water flow.

[0004] Based on the above problems, after preliminary research, the inventors proposed a method for reducing or avoiding cavitation damage of the spillway and its spillway disclosed in CN112726527A. The solution is to change the tail structure of the positive trough spillway, and let the water flow overflow to the laterally expanded spillway surface through the widened side weir, changing the flow direction and flow state. The laterally expanded spillway surface reduces the water flow velocity and the water depth on the laterally expanded spillway surface. The water flow is fully aerated on the uneven laterally expanded spillway surface, reducing the cavitation damage of the laterally expanded spillway surface. Under this technical solution, when discharging flood water, the water first flows through the control section to the discharge chute. At the tail of the discharge chute, when the water depth increases to the top of the widened side weir, the water flow turns and discharges from the widened side weir to the laterally expanded discharge surface. The bottom plate of the laterally expanded discharge surface is bedrock or sprayed anchor protection, and the bottom slope roughness is relatively large. The single-width flow becomes smaller, the water depth becomes shallower, and the water flows over the bottom plate in a sliding manner, forming a thin layer of aerated water flow, which then flows into the river channel.

[0005] However, in subsequent research by the inventors, when conducting numerical simulation analysis on the above scheme, it was found that the flow pattern in the chute was poor because the elevation of the side weir top had the same slope as the chute; water wings appeared from the end of the chute to the overflow surface of the side weir, causing the water flow to directly flow over the side weir and leave the spillway. Utility Model Content

[0006] This utility model provides a spillway that utilizes overland flow to dissipate energy over a rock surface, aiming to improve upon the aforementioned technical solution and overcome the technical problems inherent in that solution. During the design of this utility model, research was conducted on how to reduce the length of the spillway chute and lower the chute slope. Furthermore, based on the principle of graded energy dissipation, an initial energy dissipation process is performed before the spillway flood energy reaches its maximum. Then, based on the principle of overland flow, the concentrated water flow after the initial energy dissipation is converted into a large-scale overland flow over the slope, thereby saving engineering investment and improving energy dissipation.

[0007] The present invention provides the following technical solutions to achieve the above objectives:

[0008] A spillway that utilizes overflow on a rock surface to dissipate energy comprises a diversion channel section, an overflow weir, a chute and a central stilling pool arranged in sequence along the direction of descending elevation. A widened side weir is arranged on the river side of the central stilling pool, the widened side weir is connected to the surface of the rocky mountain, and diversion walls are provided on the left and right sides of the rocky mountain surface and the bottom is connected to a protective tank.

[0009] In the aforementioned spillway utilizing rock surface flow to dissipate energy, the rock mountain surface is a bedrock slope, on which a system of anchor-spray support is provided.

[0010] In the aforementioned spillway utilizing rock surface overflow for energy dissipation, the crest elevation of the widened side weir is lower than the conjugate depth of the free water level in the central stilling basin.

[0011] In the aforementioned spillway utilizing rock surface overflow for energy dissipation, the height difference between the weir crest elevation of the widened side weir and the conjugate water depth of the free water level in the central stilling pool is within the range of 1 to 1.5 times the water depth on the rock mountain surface.

[0012] In the aforementioned spillway utilizing overflow on the rock surface to dissipate energy, the overflow curve of the widened side weir is smoothly connected to the surface of the rocky mountain.

[0013] In the aforementioned spillway utilizing rock surface flow to dissipate energy, the overall slope angle of the rock mountain surface is less than 45° and the slope gradually becomes gentle from top to bottom.

[0014] In the aforementioned spillway that utilizes rock surface flow to dissipate energy, the width of the rock mountain surface is more than 4 times the width of the chute.

[0015] In the aforementioned spillway utilizing rock surface flow to dissipate energy, the surface roughness value of the rock mountain surface is greater than 0.025.

[0016] In the aforementioned spillway utilizing rock surface overflow to dissipate energy, the terrain flatness of the rock mountain surface is set within a range of 1 times the water depth of the overflow surface.

[0017] In the aforementioned spillway utilizing rock surface overflow to dissipate energy, excavated slopes are provided beside the chute and the central stilling pool.

[0018] With the above-mentioned technical solution of the present invention, when discharging flood water, the water first flows through the control section to the chute. The present invention sets up a stilling basin in the middle of the conventional chute. When the water depth increases to the top of the widened side weir on the river side of the middle stilling basin, the water flow turns and overflows from the top of the widened side weir to the rocky mountain overland flow surface. The rocky mountain overland flow surface bottom plate is protected by spray anchors, and the bottom slope roughness is relatively large. The single-width flow rate decreases, the water depth becomes shallower, and the water flows in a sliding manner over the bottom plate, forming a thin layer of aerated water flow, which merges into the river channel. Compared with the existing technology, the present invention has the following characteristics:

[0019] 1. The utility model changes the conventional spillway chute and the tail structure below, and sets the energy dissipation pool in the middle of the mountain instead of the riverbed. The water flow is introduced into the middle energy dissipation pool through the chute for initial energy dissipation, and then overflows to the surface of the rocky mountain through the widened side weir outside the middle energy dissipation pool for overflow. By changing the flow direction and flow state of the water flow, the water flow depth is reduced, and the water flow is fully aerated on the uneven rocky mountain surface, thereby accelerating energy dissipation.

[0020] 2. This utility model is suitable for reservoir spillway projects in high and steep mountainous areas with good geological conditions. By setting up a central stilling pool, the slope of the conventional chute can be slowed down and the length of the chute can be greatly shortened, thereby effectively reducing the amount of chute earthwork excavation and slope support engineering, and can effectively save project investment in high and steep mountainous terrain conditions.

[0021] 3. The utility model utilizes the surface of a rocky mountain with good geological conditions for overflow flow energy dissipation. After simple treatment, it can form a "widened spillway", making full use of the topographical and geological conditions to reduce the amount of artificial spillway construction and improve the energy dissipation effect. It is of great significance to optimize the project investment. The structure is simple and easy to construct, and a "waterfall" landscape can be formed during discharge.

[0022] 4. The utility model reduces the length of the discharge chute and slows down the slope of the discharge chute. The water flow energy flowing into the central stilling pool is relatively small. The structural size of the central stilling pool is greatly reduced compared with the conventional stilling pool set on the riverbed, which can effectively save the engineering investment of the conventional stilling pool.

[0023] 5. This utility model makes full use of the topographic and geological conditions of exposed bedrock in high and steep mountainous areas, and utilizes the large-area energy dissipation of the rocky mountain flow surface, which can not only effectively improve the energy dissipation effect, but also effectively reduce the engineering workload and investment of energy dissipation buildings.

[0024] 6. The construction of this utility model is relatively simple, and only conventional spray-anchor support is required for the overflow surface of the rocky mountain, and the foundation conditions of the energy dissipation work are relatively low. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below only relate to some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0026] Figure 1 This is a schematic diagram of the planar structure of the utility model;

[0027] Figure 2 This is a schematic diagram of the longitudinal cross-section structure of the utility model along the spillway axis;

[0028] Figure 3 This is a schematic diagram of the vertical structure of the rocky mountain flow surface of the utility model

[0029] Figure numbers: 1-diversion channel, 2-overflow weir, 3-spilling chute, 4-central stilling pool, 5-widened side weir, 6-rock mountain surface, 7-diversion wall, 8-protection tank, 9-earth-rock dam, 10-excavated slope, 11-downstream riverbed surface. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0031] It should be noted that in the present invention, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to the process, method, product, or apparatus. The terms "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or location relationships based on the positions or location relationships shown in the accompanying drawings. These terms are primarily intended to better describe the present invention and its embodiments, and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed and operated in a specific orientation. The terms "installed," "disposed," "provided with," "connected," "connected," and "sleeved" should be understood broadly, for example, and may refer to fixed connections, detachable connections, or integral structures; mechanical connections, or electrical connections; direct connections, indirect connections through an intermediate medium, or internal communication between two devices, elements, or components. Furthermore, some terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to express a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in this utility model based on the specific circumstances.

[0032] Example. A spillway that utilizes rock surface flow to dissipate energy, the structure is as follows: Figure 1-3 As shown, through this spillway, the reservoir flood flows through the diversion channel section 1, passes through the overflow weir 2, and then flows into the central stilling pool 4 through the chute 3 for initial energy dissipation.

[0033] Furthermore, this spillway is provided with a widened side weir 5 on the river side of the central stilling basin 4 to allow the water to overflow to the rocky mountain surface 6, thereby converting the concentrated water flow in the chute 3 into a large-area overflow through the central stilling basin 4 and the widened side weir 5 to reduce the depth of the water flow. The water flows over the uneven rocky mountain surface 6, is fully aerated, and accelerates energy dissipation.

[0034] Furthermore, the rock mountain surface 6 is a bedrock slope, and a systematic anchor spraying support is provided on its surface to properly level and reinforce the rock surface 6. Two diversion walls 7 are set on both sides of the rock mountain surface. After the water flows through the middle energy dissipation pool 4 and the rock mountain surface 6 twice, it falls into the protection tank 8 and finally flows into the downstream riverbed.

[0035] In specific implementation, the crest elevation of the widened side weir 5 in this spillway should be lower than the conjugate depth of the free water level in the central stilling basin, with the height difference within the range of 1 to 1.5 times the water depth of the rock face 6. The overflow curve of the widened side weir 5 should smoothly connect with the rock face 6. The overall slope angle of the rock face 6 should be less than 45°, allowing the slope to gradually decrease from top to bottom, but not from gradual to steep. The width of the rock face 6 should be at least four times the width of the chute 3. The surface of the rock face 6 should not be excessively smooth, and measures such as roughening and anchor spraying should be used to enhance its surface roughness to improve its overflow energy dissipation effect. The roughness value should be greater than 0.025. Furthermore, to avoid negative pressure, the topographic flatness of the rock face 6 should be limited and should be within 1 times the water depth of the overflow surface. This spillway has performed well under these optimal parameters.

[0036] The above-mentioned solution of this embodiment is based on the applicant and inventor's initial proposal, "A Method for Reducing or Avoiding Cavitation Damage in a Chute and Its Spillway" (Publication No.: CN112726527A). This proposal was commissioned by the applicant, China Power Engineering Group Guiyang Survey and Design Institute Co., Ltd., and Guizhou University conducted numerical simulation analysis tests in 2023 to verify and optimize it. After multiple tests, the following conclusions were reached: Numerical simulation analysis of the initial proposal revealed that the flow pattern within the chute was poor because it lacked a central stilling basin and the side weir crest had the same slope as the chute. Water wings appeared from the end of the chute to the overflow surface of the side weir, causing the water to flow directly over the side weir and out of the spillway. Therefore, the initial proposal needed to be optimized by adding a central stilling basin and adjusting the bottom slope and crest elevation of the widened side weir. After the shape adjustment, the water wave height in front of the widened side weir was reduced, reducing the pressure on the bottom plate of the central stilling basin. Widening the side weir and optimizing the weir top elevation can speed up the uniform overflow of water on the overflow surface.

[0037] Based on the above research conclusions, the initial plan was improved and optimized. The optimized implementation plan collides with the water in the central stilling basin at a distance of 57m from the inlet under the conditions of the verified flood level, the design flood level, and the normal water storage level. This reduces the water velocity, thereby mitigating the impact of the downstream water flow on the side walls and stabilizing the flow field area of the widened side weir. From the widened side weir, the water flows through the surface of the rocky mountain into the downstream riverbed. There are no negative pressure areas in the downstream riverbed. The pressure fluctuation range under the normal water storage level is 1.6m-2.5m, the pressure fluctuation range under the verified flood level is 2.5m-5m, and the pressure fluctuation range under the verified flood level is 4.2m-7.2m. The fluctuation range is relatively small, indicating that the impact of the flood on the riverbed is small after energy dissipation, indicating that the energy dissipation effect of this implementation plan is good.

[0038] Obviously, the above description is only a partial embodiment of the present invention, and not all embodiments. The above embodiments are not intended to limit the present invention. For those skilled in the art, various modifications and variations of the present invention are possible. Any combination, modification, equivalent replacement, improvement, and other embodiments that can be made by those of ordinary skill in the art within the spirit and principles of the present invention shall be within the scope of protection of the present invention.

Claims

1. A spillway utilizing overflow energy dissipation on a rock surface, characterized by: The invention comprises a diversion channel section (1), an overflow weir (2), a chute (3) and a central stilling pool (4) arranged in sequence along the direction of descending elevation; a widened side weir (5) is arranged on the river side of the central stilling pool (4); the widened side weir (5) is connected to the surface of the rocky mountain (6); diversion walls (7) are arranged on the left and right sides of the rocky mountain surface (6) and the bottom is connected to a protection tank (8).

2. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The rocky mountain surface (6) is a bedrock slope, and the rocky mountain surface (6) is provided with a system of anchor spraying support.

3. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The weir crest elevation of the widened side weir (5) is lower than the conjugate water depth of the free water level in the middle stilling basin (4).

4. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The height difference between the weir crest elevation of the widened side weir (5) and the conjugate water depth of the free water level in the middle stilling pool (4) is within the range of 1 to 1.5 times the water depth of the rocky mountain surface (6).

5. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The overflow curve of the widened side weir (5) is smoothly connected to the rocky mountain surface (6).

6. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The overall slope angle of the rocky mountain surface (6) is less than 45°, and the slope gradually decreases from steep to gentle from top to bottom.

7. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The width of the rocky mountain surface (6) is more than 4 times the width of the chute (3).

8. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The surface roughness value of the rocky mountain surface (6) is greater than 0.

025.

9. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: The terrain flatness of the rocky mountain surface (6) is set within a range of 1 times the water depth of the overland flow surface.

10. The spillway utilizing rock surface flow to dissipate energy according to claim 1, characterized in that: An excavated side slope (10) is provided beside the chute (3) and the central stilling pool (4).

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