A hydraulic engineering overflow weir and its construction method

Abstract

This invention provides an overflow weir for a hydraulic engineering project and its construction method. The overflow weir is located on the side wall of a pressure forebay, which is connected to the power plant and the mountain. The overflow weir includes a left trapezoidal block, a middle trapezoidal block, and a right trapezoidal block. By modifying the design of the overflow weir, overflow energy consumption under different water flows can be achieved, reducing the structural impact of overflow on the power plant. The construction method of the overflow weir can make full use of the connection between the side wall of the pressure forebay and the mountain and the power plant, which is convenient for construction and can ensure that the overflow weir has sufficient strength.

Description

[0001] Technical Field: This invention relates to the field of water conservancy engineering, specifically to an overflow weir for water conservancy engineering and its construction method.

[0002] Background Technology: Overflow weirs are a common form of discharge in water conservancy projects. When the water volume cannot be fully utilized by the water conservancy project, discharge structures such as overflow weirs are generally built. When the water level in front of the overflow weir is higher than the top of the weir, discharge will occur. As the water level in front of the overflow weir increases, its discharge capacity will also increase. Overflow weirs are widely used in water conservancy projects, such as canals, pressure forebays, and regulating reservoirs. However, for overflow weirs, the energy of the discharge is generally large, and even after energy dissipation, it will still cause certain water flow impact damage to the structures through which it flows.

[0003] Hydropower stations generate electricity using the energy of flowing water. In the pressure basin of a diversion-type hydropower station, an overflow weir is usually built to discharge water that the hydropower station cannot utilize. Hydropower stations generate electricity using the drop in water flow. The discharge volume of the overflow weir in the pressure basin often has a certain amount of energy. If the discharge energy of the overflow weir is large, it will affect the structural safety of the structures through which it flows. In mountainous areas, the overflow weir in the pressure basin is usually used for direct discharge. In order to make use of the limited space, the discharge channel of the overflow weir is often adjacent to the hydropower plant. If the water flow impacts the plant, it will affect the structural safety of the plant.

[0004] Summary of the Invention: This invention addresses the problems of existing technologies by providing a hydraulic engineering overflow weir and its construction method. By rationally designing the overflow weir and its construction method, the discharge stability of the overflow weir is improved.

[0005] This invention provides an overflow weir for a hydraulic engineering project. The overflow weir is located on the pressure forebay of a diversion-type hydropower station. The pressure forebay is connected to a channel and is located upstream of the powerhouse. Several turbine generator units are installed inside the powerhouse, and the turbine generator units are connected to the pressure forebay via pressure pipelines. The invention is characterized in that: one side of the pressure forebay is connected to a mountain, and an overflow weir is constructed on the side wall of the pressure forebay. One end of the side wall of the pressure forebay is connected to the mountain, and the other end is connected to the powerhouse. The overflow weir is connected to a discharge channel located between the mountain and the powerhouse. The weir comprises a left trapezoidal block, a middle trapezoidal block, and a right trapezoidal block. The left trapezoidal block is fixedly connected to the plant, and the right trapezoidal block is fixedly connected to the mountain. Gaps are provided between the middle trapezoidal block and the left trapezoidal block, and between the middle trapezoidal block and the right trapezoidal block, to form overflow channels. The elevation of the pressure forebay sidewall between the middle trapezoidal block and the left trapezoidal block is lower than the elevation of the pressure forebay sidewall between the middle trapezoidal block and the right trapezoidal block. The middle trapezoidal block and the left trapezoidal block guide the water flow towards the mountain, and the gap between the middle trapezoidal block and the right trapezoidal block guides the water flow towards the plant.

[0006] Preferably, the top elevation of the central trapezoidal block is less than the top elevations of the left and right trapezoidal blocks, while the top elevations of the left and right trapezoidal blocks are equal and both equal to the top elevation of the pressure forebay.

[0007] Preferably, the cross-sections of the left trapezoidal block, the middle trapezoidal block, and the right trapezoidal block along the height direction are trapezoidal, and the upper and lower bases of the trapezoids are parallel to the length direction of the pressure forepool sidewall. The trapezoidal cross-sections of the left trapezoidal block and the right trapezoidal block that are closer to the pressure forepool are the upper bases, and the trapezoidal cross-sections of the middle trapezoidal block that are farther away from the pressure forepool are the upper bases.

[0008] Preferably, the left trapezoidal block, the middle trapezoidal block, and the right trapezoidal block are all reinforced concrete structures, which are fixedly connected to the side wall of the pressure forebay by connecting steel bars.

[0009] Preferably, the spillway is connected to the tailrace channel of the hydropower station, and the spillway is lined with concrete.

[0010] The present invention also provides a construction method for the above-mentioned overflow weir in a hydraulic engineering project. The construction method is used to modify and install an overflow weir on the side wall of the pressure forebay. Before construction, the elevation of the side wall of the pressure forebay is equal to the elevation of the top of the pressure forebay. The method is characterized by the following steps:

[0011] S1: The sidewall of the pressure forepool is chiseled away to form a stepped surface. The stepped surface includes a first stepped surface and a second stepped surface. The first stepped surface is connected to the factory building, and the second stepped surface is connected to the mountain. The height of the second stepped surface is higher than that of the first stepped surface. The chiseled stepped surface is cleaned.

[0012] S2: Drill holes on the first and second step surfaces, and install connecting steel bars in the holes. After the connecting steel bars are placed in the holes, grout is injected into the holes and cured to the design strength. The positions of the holes and connecting steel bars are adapted to the positions of the left trapezoidal block, the middle trapezoidal block, and the right trapezoidal block. S3: Drill holes in the wall of the factory building at the location where the factory building connects to the left trapezoidal block and insert short steel bars. Drill holes in the mountain body at the location where the mountain body connects to the right trapezoidal block and insert short steel bars. After the short steel bars are inserted, grout is injected into the holes for curing.

[0013] S4: Tie the steel cages of the left trapezoidal block, the middle trapezoidal block and the right trapezoidal block respectively, wherein the steel cages of the left trapezoidal block and the right trapezoidal block are fixedly connected to the short steel bars and connecting steel bars at their respective positions, and the steel cage of the middle trapezoidal block is fixedly connected to the connecting steel bars at its respective positions.

[0014] S5: Erect formwork and pour concrete for the left trapezoidal block, the middle trapezoidal block and the right trapezoidal block. After the concrete has cured to the design strength, remove the formwork to complete the renovation of the overflow weir.

[0015] Preferably, after the first and second step surfaces are removed, they are cleaned with a high-pressure water gun. Several toothed structures are removed from both the first and second step surfaces to improve the connection strength between the first and second step surfaces and the upper poured concrete.

[0016] Preferably, the connecting steel bars at the central trapezoidal block position include connecting steel bars located on the first step surface and connecting steel bars located on the second step surface.

[0017] The working principle of this invention is as follows:

[0018] The overflow weir of the pressure forebay is designed with different discharge combinations. By incorporating left, middle, and right trapezoidal blocks, different discharge channels are formed. The elevation of the pressure forebay sidewall between the middle and left trapezoidal blocks is lower than the elevation of the sidewall between the middle and right trapezoidal blocks. Therefore, when the water level in the pressure forebay exceeds the elevation of the sidewall between the middle and left trapezoidal blocks, the water flow first passes through the discharge channel between the left and middle trapezoidal blocks. By sloping the left and middle trapezoidal blocks, the water flow is guided towards the mountainside. Thus, during low-flow discharge, the discharge primarily impacts the mountainside, keeping it away from the plant and ensuring the plant's safety. For structural safety, as the water level increases, when the water level in the pressure forebay is above the elevation of the sidewall between the central trapezoidal block and the right trapezoidal block, the water is discharged through the discharge channel between the central trapezoidal block and the right trapezoidal block. The slopes of the central trapezoidal block and the right trapezoidal block guide the water flow towards the plant. At this time, the water in the two discharge channels collides and dissipates energy, significantly reducing the energy of the discharged water and thus avoiding its impact on the plant side. When the water level exceeds the top elevation of the central trapezoidal block, maximum discharge capacity is achieved. Due to the guidance of the left trapezoidal block, direct scouring damage to the plant is reduced, protecting the plant sidewalls and foundation, and minimizing the adverse effects of water flow impact.

[0019] Since overflow from the pressure forebay wastes water resources, the overflow of the overflow weir should be reduced during the operation of the hydropower station. When the overflow is small, it should be discharged through the discharge channel between the left trapezoidal block and the middle trapezoidal block to guide the water flow towards the hillside and reduce the impact on the powerhouse. As the water level increases, the impact on the powerhouse can be reduced by combining different discharge methods. Different discharge methods should be used for different discharge flows to improve the utilization efficiency of the overflow weir and give full play to the stability of the overflow flow.

[0020] For the construction of the overflow weir, the sidewall of the original pressure forebay is removed to form a first and second step surface. The staggered step surface can not only create an elevation difference in the discharge channels between different trapezoidal blocks, but also form a stable connection with the superstructure. By using connecting steel bars and short steel bars, the connection performance between the overflow weir trapezoidal blocks and the sidewall of the pressure forebay can be improved. At the same time, the reinforced concrete structure can improve the structural strength of the trapezoidal blocks, especially under the scouring of water flow, to ensure sufficient structural performance.

[0021] The advantages of this invention are:

[0022] This invention provides an overflow weir for a hydraulic engineering project and its construction method. The overflow weir is located on the side wall of a pressure forebay, which is connected to the power plant and the mountain. The overflow weir includes a left trapezoidal block, a middle trapezoidal block, and a right trapezoidal block. By modifying the design of the overflow weir, overflow energy consumption under different water flows can be achieved, reducing the structural impact of overflow on the power plant. The construction method of the overflow weir can make full use of the connection between the side wall of the pressure forebay and the mountain and the power plant, which is convenient for construction and can ensure that the overflow weir has sufficient strength. Attached image description:

[0023] Figure 1 Schematic diagram of the forebay layout;

[0024] Figure 2 Plan view (top view) of the overflow weir layout;

[0025] Figure 3 Front view of the overflow weir layout;

[0026] Figure 4 A schematic diagram of the stepped surface removed for the pressure forebay;

[0027] Figure 5 This is a flowchart of the overflow weir construction method.

[0028] Detailed Description of Embodiments: The following description, based on the accompanying drawings, provides a detailed explanation of the scope of this invention.

[0029] This invention provides an overflow weir for a hydraulic engineering project. The overflow weir is located on the pressure forebay 1 of a diversion-type hydropower station. The pressure forebay 1 is connected to a channel and is located upstream of the powerhouse 2. Several turbine generator sets 3 are installed in the powerhouse 2. The turbine generator sets 3 are connected to the pressure forebay 1 through pressure pipes 4. The invention is characterized in that: one side of the pressure forebay 1 is connected to a mountain 5; an overflow weir is constructed on the side wall 6 of the pressure forebay 1; one end of the side wall 6 of the pressure forebay 1 is connected to the mountain 5, and the other end is connected to the powerhouse 2; the overflow weir is connected to a discharge channel located between the mountain 5 and the powerhouse 2; the overflow weir includes a left trapezoidal block 61 and a middle section... Trapezoidal block 62 and right trapezoidal block 63, wherein left trapezoidal block 61 is fixedly connected to the factory building 2, and right trapezoidal block 63 is fixedly connected to the mountain 5. A gap is provided between the middle trapezoidal block 62 and the left trapezoidal block 61, and between the middle trapezoidal block 62 and the right trapezoidal block 63, to form an overflow channel. The elevation of the side wall 6 of the pressure forepool 1 between the middle trapezoidal block 62 and the left trapezoidal block 61 is lower than the elevation of the side wall 6 of the pressure forepool 1 between the middle trapezoidal block 62 and the right trapezoidal block 63. The middle trapezoidal block 62 and the left trapezoidal block 61 guide the water flow towards the mountain 5, and the middle trapezoidal block 62 and the right trapezoidal block 63 guide the water flow towards the factory building 2.

[0030] Preferably, the top elevation of the central trapezoidal block 62 is lower than the top elevations of the left trapezoidal block 61 and the right trapezoidal block 63. The top elevations of the left trapezoidal block 61 and the right trapezoidal block 63 are equal and both equal to the top elevation of the pressure forebay 1. The upper part of the central trapezoidal block 62 is flat, forming a flat overflow weir. When the water level of the pressure forebay 1 exceeds the top elevation of the central trapezoidal block 62, a large flow capacity is formed.

[0031] Preferably, the cross-sections of the left trapezoidal block 61, the middle trapezoidal block 62, and the right trapezoidal block 63 along the height direction are trapezoidal. The upper and lower bases of the trapezoids are parallel to the length direction of the sidewall 6 of the pressure forepool 1. For the left trapezoidal block 61 and the right trapezoidal block 63, the upper base is closer to the pressure forepool 1, while for the middle trapezoidal block 62, the upper base is farther from the pressure forepool 1. The upper base is the base with the shorter trapezoidal length, and the lower base is the base with the longer trapezoidal length. The cross-sections of the left trapezoidal block 61 and the right trapezoidal block 63 can be right-angled trapezoids, and the cross-section of the middle trapezoidal block 62 can be an isosceles trapezoid.

[0032] Preferably, the left trapezoidal block 61, the middle trapezoidal block 62 and the right trapezoidal block 63 are all reinforced concrete structures, which are fixedly connected to the side wall 6 of the pressure forepool 1 by connecting steel bars, and the strength of the concrete is not lower than C25.

[0033] Preferably, the spillway is connected to the tailrace of the hydropower station, the spillway is lined with concrete, and the sidewall 6 of the spillway should be lined with a certain thickness to prevent direct water flow erosion of the sidewall 6.

[0034] The present invention also provides a construction method for the above-mentioned overflow weir of the hydraulic engineering project. The construction method is used to modify and install an overflow weir on the side wall 6 of the pressure forebay 1. Before construction, the elevation of the side wall 6 of the pressure forebay 1 is equal to the elevation of the top of the pressure forebay 1. The construction method includes the following steps:

[0035] S1: The side wall 6 of the pressure forepool 1 is chiseled away to form a stepped surface. The stepped surface includes a first stepped surface 64 and a second stepped surface 65. The first stepped surface 64 is connected to the factory building 2, and the second stepped surface 65 is connected to the mountain 5. The height of the second stepped surface 65 is higher than the height of the first stepped surface 64. The stepped surface after chiseling is cleaned.

[0036] S2: Drill holes on the first step surface 64 and the second step surface 65, and install connecting steel bars in the drill holes. After the connecting steel bars are placed in the drill holes, grout is injected into the drill holes and cured to the design strength. The positions of the drill holes and connecting steel bars are adapted to the positions of the left trapezoidal block 61, the middle trapezoidal block 62 and the right trapezoidal block 63.

[0037] S3: Drill holes into the wall of the factory building 2 at the location where the factory building 2 connects with the left trapezoidal block 61 and insert short steel bars. Drill holes into the mountain 5 at the location where the mountain 5 connects with the right trapezoidal block 63 and insert short steel bars. After the short steel bars are inserted, grouting and curing are carried out on the drilled holes respectively.

[0038] S4: Tie the steel cages of the left trapezoidal block 61, the middle trapezoidal block 62 and the right trapezoidal block 63 respectively, wherein the steel cages of the left trapezoidal block 61 and the right trapezoidal block 63 are fixedly connected to the short steel bars and connecting steel bars at their respective positions, and the steel cage of the middle trapezoidal block 62 is fixedly connected to the connecting steel bars at its respective position.

[0039] S5: Erect formwork and pour concrete for the left trapezoidal block 61, the middle trapezoidal block 62 and the right trapezoidal block 63. After the concrete has cured to the design strength, remove the formwork to complete the renovation of the overflow weir.

[0040] Preferably, after the first step surface 64 and the second step surface 65 are chiseled away, they are cleaned with a high-pressure water gun. Several tooth-shaped structures are chiseled away on the first step surface 64 and the second step surface 65 to improve the connection strength between the first step surface 64 and the second step surface 65 and the upper poured concrete. The tooth-shaped structure is a tooth-shaped groove left during chiseling. After cleaning, the tooth-shaped groove can be used to improve the bonding force between the step surface and the upper concrete.

[0041] Preferably, the connecting steel bars at the position of the central trapezoidal block 62 include connecting steel bars located on the first step surface 64 and connecting steel bars located on the second step surface 65. The concrete of the central trapezoidal block 62 is simultaneously fixedly connected to the first step surface 64 and the second step surface 65. The first step surface 64 and the second step surface 65 can be used to improve the connection strength between the central trapezoidal block 62 and the side wall 6 of the pressure forebay 1.

[0042] The above embodiments are merely preferred embodiments of the present invention. The scope of protection of the present invention should not be considered as limited to the specific forms described in the embodiments. The scope of protection of the present invention also includes equivalent technical means that can be conceived by those skilled in the art based on the concept of the present invention.

Claims

1. A spillway for a hydraulic engineering project, wherein the spillway is located on the pressure forebay of a diversion-type hydropower station, the pressure forebay is connected to a channel, the pressure forebay is located upstream of the powerhouse, and the powerhouse is equipped with a plurality of turbine generator units, the turbine generator units being connected to the pressure forebay via pressure pipelines, characterized in that: One side of the pressure forebay is connected to the mountain. An overflow weir is constructed on the side wall of the pressure forebay. One end of the side wall of the pressure forebay is connected to the mountain, and the other end is connected to the plant. The overflow weir is connected to a discharge channel located between the mountain and the plant. The overflow weir includes a left trapezoidal block, a middle trapezoidal block, and a right trapezoidal block. The left trapezoidal block is fixedly connected to the plant, and the right trapezoidal block is fixedly connected to the mountain. Gaps are provided between the middle trapezoidal block and the left trapezoidal block, and between the middle trapezoidal block and the right trapezoidal block, to form an overflow channel. The elevation of the pressure forebay side wall between the middle trapezoidal block and the left trapezoidal block is lower than the elevation of the pressure forebay side wall between the middle trapezoidal block and the right trapezoidal block. The middle trapezoidal block and the left trapezoidal block guide the water flow towards the mountain, and the middle trapezoidal block and the right trapezoidal block guide the water flow towards the plant.

2. The overflow weir of a hydraulic engineering project as described in claim 1, characterized in that: The top elevation of the central trapezoidal block is less than the top elevations of the left and right trapezoidal blocks. The top elevations of the left and right trapezoidal blocks are equal and both equal to the top elevation of the pressure forebay.

3. The overflow weir of a hydraulic engineering project as described in claim 1, characterized in that: The cross-sections of the left trapezoidal block, the middle trapezoidal block, and the right trapezoidal block along the height direction are trapezoidal. The upper and lower bases of the trapezoids are parallel to the length direction of the sidewall of the pressure forepool. The upper base of the trapezoidal cross-section of the left trapezoidal block and the right trapezoidal block is closer to the pressure forepool, while the upper base of the trapezoidal cross-section of the middle trapezoidal block is farther from the pressure forepool.

4. The overflow weir of a hydraulic engineering project as described in claim 1, characterized in that: The left trapezoidal block, the middle trapezoidal block, and the right trapezoidal block are all reinforced concrete structures, and they are fixedly connected to the side wall of the pressure forebay by connecting steel bars.

5. The overflow weir of a hydraulic engineering project as described in claim 1, characterized in that: The spillway is connected to the tailrace channel of the hydropower station, and the spillway is lined with concrete.

6. The construction method of the overflow weir in a hydraulic engineering project as described in claim 4, wherein the construction method is used to modify and install the overflow weir on the side wall of the pressure forebay, and the elevation of the side wall of the pressure forebay is equal to the elevation of the top of the pressure forebay before construction, characterized in that: The construction method includes the following steps: S1: The sidewall of the pressure forepool is chiseled away to form a stepped surface. The stepped surface includes a first stepped surface and a second stepped surface. The first stepped surface is connected to the factory building, and the second stepped surface is connected to the mountain. The height of the second stepped surface is higher than that of the first stepped surface. The chiseled stepped surface is cleaned. S2: Drill holes on the first step surface and the second step surface, and install connecting steel bars in the drill holes. After the connecting steel bars are placed in the drill holes, grout is injected into the drill holes and cured to the design strength. The positions of the drill holes and connecting steel bars are adapted to the positions of the left trapezoidal block, the middle trapezoidal block and the right trapezoidal block. S3: Drill holes into the wall of the factory building at the location where the factory building connects with the left trapezoidal block and insert short steel bars. Drill holes into the mountain at the location where the mountain connects with the right trapezoidal block and insert short steel bars. After the short steel bars are inserted, grouting and curing are carried out on the drilled holes respectively. S4: Tie the steel cages of the left trapezoidal block, the middle trapezoidal block and the right trapezoidal block respectively, wherein the steel cages of the left trapezoidal block and the right trapezoidal block are fixedly connected to the short steel bars and connecting steel bars at their respective positions, and the steel cage of the middle trapezoidal block is fixedly connected to the connecting steel bars at its respective positions. S5: Erect formwork and pour concrete for the left trapezoidal block, the middle trapezoidal block and the right trapezoidal block. After the concrete has cured to the design strength, remove the formwork to complete the renovation of the overflow weir.

7. The construction method of the overflow weir in a water conservancy project as described in claim 6, characterized in that: After the first and second step surfaces are removed, they are cleaned with a high-pressure water gun. Several toothed structures are removed from both the first and second step surfaces to improve the connection strength between the first and second step surfaces and the upper poured concrete.

8. The construction method of the overflow weir in a water conservancy project as described in claim 6, characterized in that: The connecting steel bars at the location of the central trapezoidal block include connecting steel bars located on the first step surface and connecting steel bars located on the second step surface.

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