A flood discharge gate weir crest and its design method

Abstract

This invention relates to a flood discharge gate weir crest and its design method. The design method includes: S1: establishing a single-orifice mathematical model of the flood discharge gate, determining the boundary conditions and initial flow conditions of the mathematical model, and performing numerical simulation calculations; S2: changing the length of the flood discharge gate weir crest and performing numerical simulation calculations for each change; S3: based on the calculation results of S2, determining the optimal range of the weir crest extension length using the first risk value k1 of the impact hinge as a judgment condition; S4: establishing a single-orifice physical model of the flood discharge gate, conducting physical model tests on schemes within the optimal range of the weir crest extension length determined in S3, and determining the optimal scheme of the weir crest extension length using the second risk value k2 of the impact hinge as a judgment condition. This invention first establishes a single-orifice mathematical model of the flood discharge gate to initially determine the optimal scheme, reducing the number of model modifications, material consumption, and cost of the physical model. Then, through physical model tests, it finally determines the optimal scheme of the flood discharge gate weir crest length, reducing the risk of surface water splash impacting the gate hinges.

Description

Technical Field

[0001] This invention relates to the field of flood discharge, and in particular to a flood discharge gate weir crest and its design method. Background Technology

[0002] A floodgate is a gate used to discharge floodwaters and regulate the water level of a reservoir. It releases excess water when the water level is too high, ensuring the safety of the reservoir or river, effectively preventing floods, and avoiding significant losses of life and property. At the same time, floodgates can also regulate water levels, maintain the stability of water sources and the cleanliness of water quality, and improve production efficiency and agricultural productivity.

[0003] Low-head riverbed-type sluice gates have large discharge volumes and significant downstream submersion. Hydraulic jumps may occur in the steep slope section of the gate chamber, with the jump head located close to the gate hinges. The surface water jets may impact the gate hinges, potentially affecting the stability of the hinge structure.

[0004] The weir crest length of a spillway refers to the length of the top of the spillway (i.e., the weir crest) along the direction of water flow. The weir crest length has a significant impact on the spillway's discharge capacity, water flow stability, and structural safety. The weir crest length directly affects the state of water flow. A longer weir crest helps the water flow transition more smoothly, reducing water jet jumping and splashing, thus lowering the risk of surface water impact on the gate hinges. A shorter weir crest may lead to abrupt changes in water flow, increasing the kinetic energy and impact force of the water jet, making the surface water more likely to impact the gate hinges.

[0005] In summary, there is a correlation between the length of the spillway crest and the risk of surface water jet impacting the gate hinges. When designing a spillway, multiple factors need to be considered to determine the appropriate crest length, and effective measures must be taken to reduce the risk of surface water jet impacting the gate hinges. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a flood discharge gate weir crest and its design method.

[0007] In a first aspect, the present invention provides a design method for the crest of a flood discharge gate, comprising the following steps:

[0008] S1: Establish a mathematical model of a single outlet of the flood discharge gate, determine the boundary conditions and initial water flow of the mathematical model, and perform numerical simulation calculations;

[0009] S2: Change the length of the spillway weir crest and perform numerical simulation calculations accordingly;

[0010] S3: Based on the calculation results of S2, the optimal range of the dam crest extension length is determined using the first risk value k1 of the impact hinge as the judgment condition.

[0011] S4: Establish a single-hole physical model of the flood discharge gate, conduct physical model tests on the schemes within the optimal range of the weir crest extension length determined in S3, and determine the optimal scheme of the weir crest extension length using the second risk value k2 of the impact hinge as the judgment condition.

[0012] This invention provides a flood discharge gate weir crest and its design method. First, a single-hole mathematical model of the flood discharge gate is established to study the hydraulic jump variation law, which can quickly grasp the improvement effect of optimization measures, preliminarily determine the optimal scheme, reduce the number of modifications to the physical model, and reduce the material consumption and cost of the physical model. Then, the optimal scheme determined by the mathematical model is further confirmed through physical model experiments, and finally the optimal scheme of the flood discharge gate weir crest length is determined, thereby reducing the risk of water jet impacting the gate hinges.

[0013] Preferably, in S1, the upstream boundary is a water level boundary, and the downstream boundary is a water level boundary.

[0014] Preferably, in S2, the length of the floodgate weir crest varies from 0.5m to 10m.

[0015] Preferably, in S2, the length of the flood discharge gate weir crest changes linearly, with an increment of 0.1m-0.5m.

[0016] Preferably, in S3, the expression for the first risk value k1 of the impact hinge is as follows:

[0017] k1 = f(position of the water jump, water depth at the jump, maximum near-bottom velocity of the gate chamber, discharge flow rate, water surface line of the gate chamber);

[0018] In the formula, f is a function.

[0019] Preferably, in S3, the expression for the first risk value k1 of the impact hinge is as follows:

[0020] k1 = n1f1 (position of the water jump head) + n2f2 (water depth at the jump head) + n3f3 (maximum near-bottom velocity in the lock chamber)

[0021] +n4f4 (discharge flow) +n5f5 (water level in the gate chamber);

[0022] In the formula, f1, f2, f3, f4, and f5 are functions, n1, n2, n3, n4, and n5 are coefficients, and n1+n2+n3+n4+n5=1.

[0023] Preferably, in S3, n1≥n2>n3≥n4≥n5.

[0024] Preferably, in step S4, when establishing the physical model of a single-hole floodgate, the overflow structures and the downstream apron section are made of plexiglass.

[0025] Preferably, in step S4, the expression for the second risk value k2 of the impact support hinge is as follows:

[0026] k2 = g(position of the water jump, water level in the lock chamber, pressure on the weir surface);

[0027] In the formula, g is a function.

[0028] Preferably, in step S4, the expression for the second risk value k2 of the impact support hinge is as follows:

[0029] k2 = m1g1 (position of the water jump head) + m2g2 (water level in the lock chamber) + m3g3 (pressure on the weir surface)

[0030] In the formula, g1, g2, and g3 are functions, m1, m2, and m3 are coefficients, and m1 + m2 + m3 = 1.

[0031] Preferably, in S4, m1≥m2≥m3.

[0032] In a second aspect, the present invention provides a floodgate, which is designed using any of the floodgate weir crest design methods described above.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] This invention provides a flood discharge gate weir crest and its design method. First, a single-hole mathematical model of the flood discharge gate is established to study the hydraulic jump variation law, which can quickly grasp the improvement effect of optimization measures, preliminarily determine the optimal scheme, reduce the number of modifications to the physical model, and reduce the material consumption and cost of the physical model. Then, the optimal scheme determined by the mathematical model is further confirmed through physical model experiments, and finally the optimal scheme of the flood discharge gate weir crest length is determined, thereby reducing the risk of water jet impacting the gate hinges.

[0035] This invention, through the combined use of mathematical simulation calculations and physical model experiments, can initially determine a superior scheme based on the mathematical model, and then further confirm the superior scheme determined by the mathematical model through physical model experiments, ultimately determining the optimal scheme for the length of the spillway weir crest. This significantly reduces the number of modifications to the physical model, reduces the consumption and cost of physical model materials, and improves the efficiency of physical model experiments. Moreover, the dual verification through mathematical simulation calculations and physical model experiments further ensures the feasibility and accuracy of the optimized scheme. The optimized spillway weir crest can effectively reduce the risk of surface water splash impacting the gate hinges, ensuring the safe operation of the floodgate. Attached Figure Description

[0036] Figure 1 This is a plan view of the spillway structure.

[0037] Figure 2This is a longitudinal section view of the floodgate.

[0038] Figure 3 This is a schematic diagram illustrating the risk of water droplets on the surface of the water jet impacting the gate hinges.

[0039] Figure 4 This is a schematic diagram of the mathematical model of a single outlet of a floodgate.

[0040] Figure 5 This is a boundary condition diagram for the mathematical model of the flood discharge gate.

[0041] Figure 6 This is a cross-sectional layout diagram of the broad crest weir of the flood discharge gate.

[0042] Figure 7 This is a schematic diagram of the flow field in the floodgate chamber.

[0043] Figure 8 The water surface line along the route of the dam crest extension scheme.

[0044] Figure 9 The diagram shows the shape parameters of the recommended weir crest lengthening scheme for numerical simulation.

[0045] Figure 10 This is a schematic diagram of the scope of the hydraulic physical model.

[0046] Figure 11 This is a diagram showing the overall layout of the hydraulic engineering physical model.

[0047] Figure 12 This is a layout diagram of the floodgate in the hydraulic physics model.

[0048] Figure 13 This is a comparison diagram of the hydraulic jump positions in the gate chamber.

[0049] Figure 14 This is a comparison diagram of the water level in the sluice chamber.

[0050] Figure 15 This is a comparison diagram of the pressure on the sluice gate weir surface. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0052] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0053] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0054] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing between identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0055] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0056] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0057] Example 1

[0058] The spillway structure of a certain hub mainly consists of 7 floodgates and 1 bottom outlet. The dam is 122m long and the crest elevation is 17.50m. The plan layout and longitudinal section of the spillway structure are shown below. Figure 1-2 As shown.

[0059] The seven-gate spillway is located in the main channel, with a single gate having a net width of 13.0m and a total frontal width of 116.0m. It employs a segmented pier design, with the left pier being 2.0m thick, the middle pier 3.5m thick, and the right pier 2.0m thick, resulting in a single-gate span width of 16.50m. The spillway crest elevation is 17.50m, the weir crest elevation is 1.00m, and the gate chamber is 35.0m long in the direction of water flow. From upstream to downstream, a flat inspection gate and an arc-shaped working gate are sequentially installed. The inspection gate is opened and closed using a mobile gantry crane on the dam crest, while the working gate is opened and closed using a hydraulic hoist. A 4.8m wide traffic bridge is located upstream of the gate crest, with a bridge crest elevation of 17.50m. Two gantry crane track beams are located adjacent to the traffic bridge, and a cable and oil pipeline box girder is located downstream. The spillway weir is a broad-crested weir, with a crest elevation of 1.00m for all sections. After the floodgate, it connects to the sea via a 1:4 slope. The sea is 100m long and has a rock-filled anti-scour trough at the end.

[0060] This dam is a low-head riverbed dam with a large flood discharge and significant downstream submersion. Under the check conditions, the hydraulic jump occurs on a steep slope of the dam chamber, with the jump head located close to the gate hinges. The surface water jet poses a risk of impacting the gate hinges, potentially negatively affecting their stability. Figure 3 As shown.

[0061] Consider optimizing the gate chamber's structure to shift the hydraulic jump location downstream, thereby reducing the water depth at the hinge location. Specifically:

[0062] A design method for the crest of a flood discharge gate includes the following steps:

[0063] S1: Establish a mathematical model of a single outlet of the floodgate, determine the boundary conditions and initial water flow of the mathematical model, and perform numerical simulation calculations.

[0064] Mathematical model of a single spillway gate as follows Figure 4 As shown. The model's research range is from 10m upstream of the dam to 120m downstream. The upstream boundary uses a water level boundary with a water level set at 15.17m, and the downstream boundary uses a water level boundary with a water level set at 11.74m. The boundary conditions and initial flow settings for the mathematical model are shown below. Figure 5 .

[0065] S2: Change the length of the spillway weir crest and perform numerical simulation calculations to study the hydraulic jump change law and quickly grasp the improvement effect of the optimization measures.

[0066] When changing the length of the spillway weir crest, the range of variation for the spillway weir crest length can be 0.5m-10m, that is, the spillway weir crest length can be increased from 0.5m to about 10m, and mathematical simulation calculations are performed accordingly.

[0067] Furthermore, when changing the length of the spillway crest, the length can change linearly or non-linearly. Typically, the increment of the spillway crest length is 0.1m-0.5m. For example, using a 0.5m increment, the increase in the spillway crest length would be 0.5m, 1m, 1.5m, 2m, and so on. Alternatively, it can change non-linearly, for example, with increases of 1m, 2m, and 5m, etc.

[0068] Considering extending the straight section of the weir crest (elevation 1.00m), the cross-sectional layout of the broad-crested weir of the flood discharge gate is as follows: Figure 6 As shown in Table 1, the calculation conditions and statistical results are presented, and the longitudinal flow field results for each scheme are as follows. Figure 7 As shown, the water surface line along the path is as follows Figure 8 As shown. According to the settlement results, lengthening the straight section of the weir crest will slightly reduce the flow rate; an increase of 5m will reduce it by approximately 0.5%.

[0069] The hydraulic jump head was moved down by about 1.5m and 3.0m respectively when the length was increased by 1m and 2m, and the water depth at the contraction section did not change much. When the length was increased by 5m, although the hydraulic jump head was moved down, the water depth at the contraction section increased significantly, which, according to the flow field distribution diagram, increased the risk of impact on the hinge.

[0070] Table 1. Calculation conditions and statistical results of the weir crest lengthening scheme.

[0071]

[0072] S3: Based on the calculation results of S2, it can be seen that the longer the dam crest extension length is not necessarily better. The optimal range of the dam crest extension length is determined by using the first risk value k1 of the impact hinge as the judgment condition.

[0073] In S3, the expression for the first risk value k1 of the impact support hinge can be as follows:

[0074] k1 = f(position of the water jump, water depth at the jump, maximum near-bottom velocity of the gate chamber, discharge flow rate, water surface line of the gate chamber);

[0075] In the formula, f is a function.

[0076] When calculating the first risk value k1 of the impact hinge, it is necessary to first identify the influencing factors affecting the impact hinge risk. Through research and analysis, it was determined that the first risk value k1 of the impact hinge is highly correlated with the position of the hydraulic jump, the depth of the jump, the maximum near-bottom velocity of the gate chamber, the discharge flow rate, and the water surface line of the gate chamber. That is, the position of the hydraulic jump, the depth of the jump, the maximum near-bottom velocity of the gate chamber, the discharge flow rate, and the water surface line of the gate chamber are the influencing factors.

[0077] Furthermore, in S3, the expression for the first risk value k1 of the impact support hinge can be as follows:

[0078] k1 = n1f1 (position of the water jump head) + n2f2 (water depth at the jump head) + n3f3 (maximum near-bottom velocity in the lock chamber)

[0079] +n4f4 (discharge flow) +n5f5 (water level in the gate chamber);

[0080] In the formula, f1, f2, f3, f4, and f5 are functions, and n1, n2, n3, n4, and n5 are coefficients, with n1 + n2 + n3 + n4 + n5 = 1. n1, n2, n3, n4, and n5 represent the importance of different influencing factors. The values ​​of n1, n2, n3, n4, and n5 can be different, with larger values ​​indicating greater importance.

[0081] In the calculation of impact hinge risk, the most important influencing factors are identified and assigned the largest coefficient. By setting different levels of importance, the first risk value k1 of the impact hinge can be obtained more accurately.

[0082] Furthermore, n1≥n2>n3≥n4≥n5. That is, the influence and importance of the position and depth of the hydraulic jump head are generally greater than the influence and importance of the maximum bottom velocity, discharge capacity, and water surface line of the lock chamber.

[0083] Based on the numerical simulation results of lengthening by 1m, 2m and 5m, the schemes of lengthening by 1m and 2m are recommended as the better schemes, that is, the optimal range for lengthening the dam crest is 1-2m.

[0084] S4: Establish a single-hole physical model of the flood discharge gate, conduct physical model tests on the schemes within the optimal range of the weir crest extension length determined in S3, and determine the optimal scheme of the weir crest extension length using the second risk value k2 of the impact hinge as the judgment condition.

[0085] Based on the preliminary optimization results of the numerical model, the physical model was tested against the recommended schemes (schemes with a 1m and 2m extension of the weir crest). The scheme layout is as follows: Figure 9 As shown.

[0086] When establishing a physical model of a single outlet of a flood discharge gate, follow these steps:

[0087] Model scale:

[0088] The hydraulic simulation of the spillway structure adopts a normal distribution model. Based on the experimental research content, and taking into account the experimental site conditions, minimum water depth, and Reynolds number constraints, the model scale is set to 40, and it needs to satisfy geometric similarity, velocity similarity, resistance similarity, and flow rate similarity.

[0089] In addition, the model should also satisfy (1) the model water flow must be turbulent, that is, the model Reynolds number ≥ 1000.

[0090] In the formula, V is the water flow velocity (m / s); R is the hydraulic radius (m); and v is the water flow viscosity coefficient.

[0091] (2) Minimum water depth limit: To avoid the influence of surface tension, the minimum water depth of the model test section should not be less than 0.03m.

[0092] Model range:

[0093] Based on the topographic data of the key river section and considering the requirement for similar inlet and outlet flow conditions in the model, to ensure that the flow pattern within the experimental section remains unaffected, the physical model study area is taken from 510m upstream of the dam site to 650m downstream of the dam site, simulating a river section length of approximately 1.16km. For details of the model range, please refer to [link to details]. Figure 10 .

[0094] Model making:

[0095] The model is supplied with water by a water supply system, with a leveling section and stabilizing barriers upstream to ensure stable water flow in the reservoir area. Both the reservoir area and the downstream river channel are simulated based on actual terrain. The terrain modeling employs the cross-sectional method, with the model cross-section scaled down to the measured riverbed topography according to both planar and vertical scales. The model cross-section is constructed of five layers of slabs, erected by a pre-arranged main control system. The elevation control error is less than ±1.0 mm, and the planar control error is less than ±1.0 cm. The terrain surface is finished with cement mortar. Floodgates, bottom outlets, power stations, and other flow-passing structures, as well as the downstream apron section, are made of processed plexiglass for convenient flow field observation and parameter measurement. The simulated river section is entirely lined with concrete. The prototype roughness is 0.012–0.014, while the model roughness is required to be 0.006–0.008. Cement mortar finishing and plexiglass meet the roughness requirements. The on-site layout of the model is shown in Figures 11-12.

[0096] Measurement and control instruments and equipment:

[0097] The main measurement and control instruments and equipment for the model test include:

[0098] Flow rate: Siemens electromagnetic flowmeters are used for control and measurement.

[0099] Tailgate water level: Controlled and adjusted using a flap-type tailgate with fine-tuning function.

[0100] Water level along the route: measured using a water level gauge.

[0101] Average pressure: Measured using a pressure gauge.

[0102] Pulsating pressure: Measured using a resistive pulsating pressure sensor.

[0103] Flow velocity: Measured using a new type of acoustic Doppler three-dimensional point velocity meter and propeller velocity meter made in Norway.

[0104] After the physical model of the single-hole spillway was established, considering both the flood control conditions of the dam and the energy dissipation and scour prevention conditions of the downstream apron and riverbed, three typical characteristic water levels—verification (P=0.1%), design (P=1%), and energy dissipation and scour prevention (P=2%)—were selected for testing, as shown in Table 2. Flow patterns, water surface elevation along the spillway, bottom velocity along the spillway, hourly average pressure on the spillway floor, and pulsating pressure on the downstream apron floor were tested at various flow rates. The water level boundary control positions on the model dam were 400m upstream and 600m downstream, respectively, and the water levels were controlled according to Table 2.

[0105] Table 2. Test conditions of the floodgate

[0106]

[0107] The water jump head position, gate chamber water surface line, and weir surface pressure distribution were tested under specified operating conditions after the weir crest was lengthened. The specific results are as follows.

[0108] (1) Water Jump Head Position

[0109] Hydraulic jump of the gate chamber under the original design scheme and the scheme with the weir crest lengthened (1m, 2m) Figure 13 It can be seen that after the weir crest was lengthened, the position of the water jump head shifted significantly downwards. With a 1m increase in weir crest length, the water jump head position is at 0+035.56m downstream of the dam, a shift of 1m compared to the original design. With a 2m increase in weir crest length, the water jump head position is at 0+037.46m downstream of the dam, a shift of 2.9m compared to the original design. Under the weir crest lengthening scheme, the risk of water jet impacting the gate hinges is eliminated.

[0110] (2) Water level and pressure

[0111] The water level in the gate chamber and the pressure distribution on the weir surface under the original design scheme and the weir crest extension scheme (1m, 2m) are shown below (along the centerline of No. 4 spillway gate). Figure 14 , Figure 15 Corresponding to the flow diagram, under the extended weir crest scheme, the water level at the weir crest rises slightly, and the position of the hydraulic jump head shifts downward to 100m downstream of the dam. The water level lines of the original design and the extended weir crest scheme are basically consistent. The weir surface pressure is positive pressure in both cases.

[0112] Specifically, in S4, the expression for the second risk value k2 of the impact support hinge is as follows:

[0113] k2 = g(position of the water jump, water level in the lock chamber, pressure on the weir surface);

[0114] In the formula, g is a function.

[0115] When calculating the second risk value k2 of the impact hinge, it is first necessary to identify the influencing factors affecting the impact hinge risk. Numerical simulation results show that the position of the hydraulic jump and the water surface line of the gate chamber have a significant impact on the impact hinge risk. Therefore, the position of the hydraulic jump and the water surface line of the gate chamber are selected as influencing factors for the second risk value k2 of the impact hinge. Weir pressure is also added as an influencing factor. This demonstrates that the selection of influencing factors can be further optimized through numerical simulation results. For example, the position of the hydraulic jump and the water surface line of the gate chamber can be selected as influencing factors for the second risk value k2 of the impact hinge, while the gate head water depth, the maximum near-bottom velocity of the gate chamber, and the discharge flow rate are no longer considered as influencing factors. This further optimizes the calculation expression for the second risk value k2, facilitating a more accurate risk assessment result.

[0116] In S4, the expression for the second risk value k2 of the impact support hinge can be as follows:

[0117] k2 = m1g1 (position of the water jump head) + m2g2 (water level in the lock chamber) + m3g3 (pressure on the weir surface)

[0118] In the formula, g1, g2, and g3 are functions, and m1, m2, and m3 are coefficients, with m1 + m2 + m3 = 1. The values ​​of m1, m2, and m3 can be different, with larger values ​​indicating greater importance.

[0119] In the calculation of impact hinge risk, the most important influencing factors are identified and assigned the largest coefficient. By setting different levels of importance, the second risk value k2 of the impact hinge can be obtained more accurately.

[0120] Furthermore, m1 ≥ m2 ≥ m3. That is, the influence and importance of the position of the hydraulic jump head are generally greater than the influence and importance of the water surface line in the gate chamber, and the influence and importance of the water surface line in the gate chamber are greater than the influence and importance of the weir pressure.

[0121] For example, in this embodiment, among the recommended schemes (schemes with a 1m and 2m increase in weir crest length) determined by numerical simulation, the scheme with a 2m increase in weir crest length is further determined to be the optimal scheme because the position of the water jump head is farther from the spur in the scheme with a 2m increase in weir crest length, and the water surface line is basically consistent with the original design scheme, and the weir surface pressure is positive pressure in both cases.

[0122] This invention provides a design method for the crest of a flood discharge gate. First, a mathematical model of a single-hole flood discharge gate is established to study the hydraulic jump variation law, enabling rapid understanding of the improvement effects of optimization measures and preliminary determination of a superior scheme. This reduces the number of modifications to the physical model; for example, in this embodiment, the physical model was modified only twice (for the crest lengthening schemes of 1m and 2m), reducing material consumption and cost, and improving the efficiency of physical model testing. Next, the superior scheme determined by the mathematical model is further confirmed through physical model testing, ultimately determining the optimal scheme for the crest length of the flood discharge gate.

[0123] This invention, through the combined use of mathematical simulation calculations and physical model experiments, can initially determine a superior scheme based on the mathematical model, and then further confirm the superior scheme determined by the mathematical model through physical model experiments, ultimately determining the optimal scheme for the length of the spillway weir crest. This significantly reduces the number of modifications to the physical model, reduces the consumption and cost of physical model materials, and improves the efficiency of physical model experiments. Moreover, the dual verification through mathematical simulation calculations and physical model experiments further ensures the feasibility and accuracy of the optimized scheme. The optimized spillway weir crest can effectively reduce the risk of surface water splash impacting the gate hinges, ensuring the safe operation of the floodgate.

[0124] Example 2

[0125] A floodgate is designed using the floodgate weir crest design method described in Example 1.

[0126] The floodgate described in this invention is designed using the design method of Embodiment 1. By optimizing the length of the floodgate weir crest, the risk of water jets impacting the gate hinges can be effectively reduced, ensuring the safe operation of the floodgate.

[0127] 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 design method for the crest of a flood discharge gate, characterized in that, Includes the following steps: S1: Establish a mathematical model of a single outlet of the flood discharge gate, determine the boundary conditions and initial water flow of the mathematical model, and perform numerical simulation calculations; S2: Change the length of the spillway weir crest and perform numerical simulation calculations accordingly; S3: Based on the calculation results of S2, the first risk value of the impact hinge is... k 1 is used as a criterion to determine the optimal range for the length of the dam crest extension; S4: Establish a physical model of a single-hole spillway gate, and conduct physical model tests on schemes within the optimal range of the weir crest extension length determined in S3, using the second risk value of the impact hinge. k 2 is used as a judgment condition to determine the optimal solution for extending the dam crest length; In S3, the first risk value of the impact support hinge k The expression for 1 is as follows: k 1= n 1 f 1 (Water Jump Head Position) + n 2 f 2 (leaping head water depth) + n 3 f 3 (maximum bottom velocity of the gate chamber) + n 4 f 4 (outflow) + n 5 f 5 (Water level in the lock chamber); In the formula, f 1. f 2. f 3. f 4. f 5 are functions, n 1. n 2. n 3. n 4. n 5 represents the coefficients. n 1+ n 2+ n 3+ n 4+ n 5 = 1; In S4, the second risk value of the impact support hinge k The expression for 2 is as follows: k 2= m 1 g 1 (Water Jump Head Position) + m 2 g 2 (water level in the lock chamber) + m 3 g 3 (Weir pressure) In the formula, g 1. g 2. g 3 are functions, m 1. m 2. m 3 represents the coefficients. m 1+ m 2+ m 3 = 1.

2. The design method for the crest of a flood discharge gate according to claim 1, characterized in that, In S1, the upstream boundary is a water level boundary, and the downstream boundary is a water level boundary.

3. The design method for the crest of a flood discharge gate according to claim 1, characterized in that, In S2, the length of the floodgate weir crest varies from 0.5m to 10m.

4. The design method for the crest of a flood discharge gate according to claim 1, characterized in that, In S2, the length of the floodgate weir crest changes linearly, with an increment of 0.1m-0.5m.

5. The design method for the crest of a flood discharge gate according to claim 1, characterized in that, In S3, n 1≥ n 2> n 3≥ n 4≥ n 5.

6. The design method for the crest of a flood discharge gate according to claim 1, characterized in that, In S4, when establishing the physical model of a single-hole floodgate, the overflow structures and the downstream apron section are made of plexiglass.

7. The design method for the crest of a flood discharge gate according to claim 1, characterized in that, In S4, m 1≥ m 2≥ m 3.

8. A floodgate, characterized in that, It was designed using a floodgate weir crest design method as described in any one of claims 1-7.

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