A method for estimating peak value of front ponding of emergency closure gate of controlled channel

Abstract

The application discloses a kind of emergency closing gate front backwater peak estimation method of gated channel, comprising the following steps: S1, one-dimensional unsteady flow simulation model of channel is constructed;S2, determine typical working condition of emergency control;S3, according to the simulation model in step S1, the typical working condition in step S2 is simulated, and the gate front backwater peak value of typical working condition is determined;S4, according to the gate front backwater peak value of typical working condition in step S3, draw gate front backwater peak value curve cluster;S5, according to the gate front backwater peak value curve cluster in step S4, determine the range of gate front backwater peak value when emergency disposal;S6, according to the gate front backwater peak value curve cluster in step S4, determine the accurate gate front backwater peak value when emergency disposal.The application has high estimation accuracy, is convenient and fast to use, can quickly and accurately estimate the gate front backwater peak value under different gate initial flow and gate flow amplitude, can not only simply and quickly estimate the range of gate front backwater peak value, but also can more accurately determine the gate front backwater peak value.

Description

Technical Field

[0001] This invention relates to the field of peak backlog estimation in front of a sluice gate, and specifically to a method for estimating peak backlog in front of a sluice gate during emergency closure of a gate-controlled channel. Background Technology

[0002] For long-distance open channel water conveyance projects and large irrigation area water conveyance channels, control gates are installed at regular intervals to facilitate the regulation of water level and flow, dividing the channel into series segments. When a segment experiences sudden water pollution, equipment failure, natural disaster, or engineering accident, the gates at both ends are simultaneously and rapidly closed, or even completely shut, creating conditions for emergency response. At this time, the water flow velocity within the segment changes abruptly, generating a downstream-propagating sluice wave behind the upstream gate and a upstream-propagating backflow wave in front of the downstream gate, such as... Figure 1 As shown, excessively high peak values ​​of backwater waves in front of the sluice gate can lead to water overflow and even secondary disasters, directly impacting operational safety and dispatching decisions. For frontline managers, the ability to quickly and accurately estimate peak backwater levels in front of the sluice gate during emergencies is crucial for scientific decision-making in emergency control.

[0003] The channel is a strongly nonlinear system, which can be described by the Saint-Venant equations, and the peak backwater level in front of the gate cannot be solved analytically. Existing research shows that the peak backwater level in front of the gate is mainly related to the initial flow rate before the gate closes and the flow rate drop when the gate closes. Frontline managers mainly make judgments based on their accumulated experience, and the accuracy of their estimation of the peak backwater level in front of the gate varies from person to person. Some people use simplified estimation formulas based on wave-breaking theory, such as the trial calculation formula in the Tsinghua University edition of "Hydraulics" and the simplified formula derived by Li Zhanqing of Zhengzhou University. However, because these formulas are derived based on a single prismatic channel assumption and ignore the effects of gravity and bottom slope resistance, the estimation error is relatively large when used in actual channel projects where the cross-sectional shape varies along the channel. Using a one-dimensional unsteady flow calculation simulation model based on the Saint-Venant equations can simulate the water flow characteristics more accurately and estimate the peak backwater level in front of the gate. However, the simulation model is only built for a specific working condition, and a new model needs to be built when the initial flow rate and flow rate change. Unexpected events in actual channels are unpredictable. Temporarily building simulation models to estimate the peak water backflow in front of the gate requires daily management personnel to be proficient in relevant technologies. Both modeling and simulation take time, which may delay valuable emergency response time. Summary of the Invention

[0004] In view of the above-mentioned shortcomings in the prior art, the present invention provides a method for estimating the peak water backflow in front of the gate during emergency closure of a gate-controlled channel, which can quickly and accurately estimate the peak water backflow in front of the gate under different initial gate flow rates and gate flow rate variations.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0006] A method for estimating the peak backwater level before emergency closure of a gate-controlled channel includes the following steps:

[0007] S1. Construct a one-dimensional non-steady flow simulation model of the channel;

[0008] S2. Determine typical operating conditions for emergency control;

[0009] S3. Simulate the typical working conditions in step S2 based on the simulation model in step S1, and determine the peak value of the backwater in front of the gate under the typical working conditions.

[0010] S4. Draw a cluster of peak backwater curves in front of the gate based on the peak backwater value of the typical working conditions in step S3.

[0011] S5. Based on the cluster of peak water backflow curves in front of the gate in step S4, determine the range of the peak water backflow during emergency response.

[0012] S6. Based on the cluster of peak water backflow curves in front of the gate in step S4, determine the precise peak water backflow in front of the gate during emergency response.

[0013] Further, step S1 includes the following sub-steps:

[0014] S11. Obtain the channel structure dimensions and hydraulic parameters;

[0015] S12. Based on the channel structure size parameters and hydraulic parameters obtained in step S11, establish a set of hydrodynamic equations;

[0016] S13. Input the initial conditions, upstream boundary conditions and downstream boundary conditions, and use the finite difference method to discretize the hydrodynamic equations established in step S12.

[0017] S14. The hydrodynamic equation set composed of the discrete equations in step S13 is calculated iteratively using the chasing method, and the dynamic response of water level and flow rate at each cross-section of the channel over time is output.

[0018] Furthermore, step S12 includes the following sub-steps:

[0019] S121. Based on the Saint-Venant equations, which consist of the continuity equation and the momentum equation, establish the hydrodynamic equations for the channel section:

[0020]

[0021] in: A For the water flow area, t Using time as the coordinate, Q For traffic, x For spatial coordinates, Let g be the lateral inflow rate per unit length of the channel, and g be the acceleration due to gravity. z For water level,n The roughness coefficient, R The hydraulic radius;

[0022] S122. Based on the dimensionless formula for gate flow, establish the hydrodynamic equations for the control gate section:

[0023]

[0024] in: , The unit width flow rate of the gate. This represents the opening degree of the gate. and An empirical coefficient related to gate type and flow rate. The difference in water level between the upstream and downstream sides of the sluice gate. , The water level upstream of the sluice gate. This refers to the water level downstream of the sluice gate.

[0025] Furthermore, step S13 includes the following sub-steps:

[0026] S131. Using the Preissmann discretization scheme, calculate the variables and their partial derivatives with respect to time and space in the Saint-Venant equations. The calculation formula is as follows:

[0027]

[0028]

[0029]

[0030] in: This is the original equation of the Saint-Venant system of equations. These are the discrete equations of the Saint-Venant equations. For time weighting coefficients, Spatial weighting coefficient, j For process distance The x-axis represents time. In a rectangular grid formed by the vertical coordinates, parallel to s The straight line on the axis Position numbering on the axis i To be parallel to t The straight line on the axis s Position numbering on the axis For spatial step size, For time step;

[0031] S132. Based on the partial derivatives calculated in step S131, establish the discrete equations for the continuity equations in the Saint-Venant equation system:

[0032]

[0033] in: , B The width of the water surface. B M For grid eccentricity points in the Preissmann discrete scheme M The width of the water surface at the cross-section, i.e., the subscript M Indicates in M Values ​​are taken at the cross-section. , , , ;

[0034] S133. Based on the partial derivatives calculated in step S131, establish the discrete equations of the momentum equation in the Saint-Venant equation system:

[0035]

[0036] in: , , ,

[0037] ,

[0038]

[0039] subscript in the formula z The independent variable representing the partial derivative is z That is, the water level;

[0040] S134. Using the water level and flow rate at each discrete cross-section of the channel at the initial moment as the initial conditions for the spatiotemporal discrete hydrodynamic equations, establish the upstream boundary condition discrete equations based on the inflow rate of the channel:

[0041]

[0042] in: a 0、 b 0 and e 0 represents the coefficient of variation. The initial water level at the upstream boundary section. The initial flow rate at the upstream boundary section;

[0043] S135. Based on the downstream flow-water level relationship, establish the discrete equations for the downstream boundary conditions:

[0044]

[0045] in:, aN , d N 、e N For discrete coefficients, The initial water level at the downstream boundary section. This represents the flow rate at the downstream boundary section at the initial moment.

[0046] Furthermore, the typical operating conditions include the gate fully closed under the design flow rate, the gate fully closed under the medium flow rate, the gate partially closed under the design flow rate, and the gate partially closed under the medium flow rate.

[0047] Furthermore, step S4 includes the following sub-steps:

[0048] S41. Establish a coordinate system with the flow rate variation as the horizontal axis and the peak backwater level in front of the gate as the vertical axis. The horizontal axis is also used to measure the initial flow rate of the gate.

[0049] S42. Plot the peak backwater curves in front of the gate when the gate is fully closed under different initial flow rates of the gate.

[0050] S43. Plot the peak backwater curves for different gate flow amplitudes under the same initial gate flow.

[0051] Furthermore, in step S42, a quadratic polynomial trend line with an intercept of 0 is drawn using the origin of the coordinate system, the coordinate points corresponding to the gate fully closed under the design flow rate, and the coordinate points corresponding to the gate fully closed under the medium flow rate.

[0052] Furthermore, in step S43, a quadratic polynomial trend line with an intercept of 0 is drawn using the origin of the coordinate system, the coordinate points corresponding to the fully closed gate condition under the design flow rate, and the coordinate points corresponding to the partially closed gate condition under the design flow rate.

[0053] Furthermore, step S5 includes the following sub-steps:

[0054] S51. Obtain the gate flow rate variation for emergency response;

[0055] S52. Determine the minimum peak backwater level in front of the gate based on the flow rate variation in step S51 and the curve drawn in step S42.

[0056] S53. Based on the flow rate variation in step S51 and the curve drawn in step S43, determine the maximum peak value of the backwater in front of the gate.

[0057] Furthermore, step S6 includes the following sub-steps:

[0058] S61. Determine the precise curve plotting point based on the initial flow rate of the gate during emergency response and the curve drawn in step S42.

[0059] S62. Draw the straight line determined by the precise curve drawing point and the origin in step S61.

[0060] S63. Based on the gate flow rate variation during emergency response and the straight line drawn in step S62, determine the precise peak value of the backwater in front of the gate.

[0061] The beneficial effects of this invention are as follows:

[0062] (1) The present invention can quickly and accurately estimate the peak value of backwater in front of the gate under different initial flow rates and gate flow rate variations. Depending on the accuracy requirements, it can easily and quickly estimate the range of the peak value of backwater in front of the gate, or it can determine the peak value of backwater in front of the gate in a more complex but more accurate manner.

[0063] (2) Compared with traditional manual experience judgment, calculation formula or simulation method, the present invention has high estimation accuracy and is convenient and quick to use. Attached Figure Description

[0064] Figure 1 A diagram showing the water wave motion caused by the rapid closure of the channel;

[0065] Figure 2 A flowchart illustrating a method for estimating the peak water backflow before emergency closure of a gate-controlled channel;

[0066] Figure 3 Flowchart for constructing a one-dimensional non-steady flow simulation model of a channel;

[0067] Figure 4 This is a schematic diagram of the computational grid;

[0068] Figure 5 A schematic diagram of the Preissmann discrete scheme;

[0069] Figure 6 A schematic diagram of letter markings for estimating the peak water backflow before the emergency closure of a gate-controlled channel;

[0070] Figure 7 This is a schematic diagram of letter markings for an embodiment of a method for estimating the peak water backlog before the emergency closure of a gate-controlled channel. Detailed Implementation

[0071] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0072] like Figure 2As shown, the present invention provides a method for estimating the peak water backflow before emergency closure of a gate-controlled channel, comprising steps S1-S6:

[0073] S1. Construct a one-dimensional unsteady flow simulation model of the channel.

[0074] In an optional embodiment of the present invention, a program model is independently developed based on the Saint-Venant equations and the water level-discharge relationship equations of the canal system, following the methods found in conventional hydraulics textbooks. The constructed simulation model can simulate the dynamic changes in water level and flow rate before and after the gate caused by the rapid closure of the gate during emergency channel regulation. The specific process for constructing a one-dimensional unsteady flow simulation model of the channel in this invention is as follows: Figure 3 As shown.

[0075] Step S1 includes the following sub-steps:

[0076] S11. Obtain the channel structure dimensions and hydraulic parameters.

[0077] In an optional embodiment of the present invention, the basic data for preparing the simulation model includes structural dimensional parameters such as station number, bottom width, side slope, and bottom elevation of each water-passing section along the channel, as well as hydraulic parameters such as roughness, gate flow coefficient, flow rate of each water-passing section, water level, and gate opening.

[0078] S12. Based on the channel structure size parameters and hydraulic parameters obtained in step S11, establish a set of hydrodynamic equations.

[0079] In an optional embodiment of the present invention, the present invention establishes a set of hydrodynamic equations describing the characteristics of water flow based on channel structure size parameters and hydraulic parameters. The set of hydrodynamic equations includes the hydrodynamic equations of the channel section and the hydrodynamic equations of the control gate section.

[0080] Step S12 includes the following sub-steps:

[0081] S121. Based on the Saint-Venant equations, which consist of the continuity equation and the momentum equation, establish the hydrodynamic equations for the channel section:

[0082]

[0083] in: A For the water flow area, t Using time as the coordinate, Q For traffic, x For spatial coordinates, Let g be the lateral inflow rate per unit length of the channel, and g be the acceleration due to gravity. z For water level, n The roughness coefficient, R The radius is the hydraulic radius.

[0084] S122. Based on the dimensionless formula for gate flow, establish the hydrodynamic equations for the control gate section:

[0085]

[0086] in: , The unit width flow rate of the gate. This represents the opening degree of the gate. and An empirical coefficient related to gate type and flow rate. The difference in water level between the upstream and downstream sides of the sluice gate. , The water level upstream of the sluice gate. This refers to the water level downstream of the sluice gate.

[0087] S13. Input the initial conditions, upstream boundary conditions, and downstream boundary conditions, and use the finite difference method to discretize the hydrodynamic equations established in step S12.

[0088] In an optional embodiment of the present invention, the discretized gate flow formula is used as the internal boundary condition of the channel hydrodynamic equations. Let the upstream and downstream sections of the control gate be... and The discrete form of the gate flow formula is the same as the discrete form of the Saint-Venant equations. Therefore, the discrete equations of the hydrodynamic equations in this invention include the discrete equations of the continuity equation, the discrete equations of the momentum equation, the discrete equations of the internal boundary, the discrete equations of the upstream boundary conditions, and the discrete equations of the downstream boundary conditions.

[0089] In this invention, the discrete scheme adopts the Preissmann scheme, such as... Figure 4 and Figure 5 As shown: by process distance The x-axis represents time. Using the ordinate as the vertical axis, the spatial step size is selected based on the original data, computational accuracy, and stability requirements. and time step In the independent variable The grid above forms a rectangular grid, and point M in the grid is located in the grid ([ i , i +1][ j , j Within +1]), point M is at a distance from the known time. for From an unknown time for ; From point M to spatial node The distance is ,in, This is the time weighting coefficient, typically taken as (0.5, 1], and usually 0.6; The spatial weighting coefficient is usually taken as... hour.

[0090] Step S13 includes the following sub-steps:

[0091] S131. Using the Preissmann discretization scheme, calculate the variables and their partial derivatives with respect to time and space in the Saint-Venant equations. The calculation formula is as follows:

[0092]

[0093]

[0094]

[0095] in: This is the original equation of the Saint-Venant system of equations. These are the discrete equations of the Saint-Venant equations. For time weighting coefficients, Spatial weighting coefficient, j For process distance The x-axis represents time. In a rectangular grid formed by the vertical coordinates, parallel to s The straight line on the axis Position numbering on the axis i To be parallel to t The straight line on the axis s Position numbering on the axis For spatial step size, For time step.

[0096] S132. Based on the partial derivatives calculated in step S131, establish the discrete equations for the continuity equations in the Saint-Venant equation system:

[0097]

[0098] in: , B The width of the water surface. B M For grid eccentricity points in the Preissmann discrete scheme M The width of the water surface at the cross-section, i.e., the subscript M Indicates in M Values ​​are taken at the cross-section. , , , .

[0099] S133. Based on the partial derivatives calculated in step S131, establish the discrete equations of the momentum equation in the Saint-Venant equation system:

[0100]

[0101] in: , , ,

[0102] ,

[0103]

[0104] subscript in the formula z The independent variable representing the partial derivative is z That is, the water level.

[0105] S134. Using the water level and flow rate at each discrete cross-section of the channel at the initial moment as the initial conditions for the spatiotemporal discrete hydrodynamic equations, establish the upstream boundary condition discrete equations based on the inflow rate of the channel:

[0106]

[0107] in: a 0、 b 0 and e 0 represents the coefficient of variation. , , , The initial water level at the upstream boundary section. This represents the flow rate at the upstream boundary section at the initial moment.

[0108] S135. Based on the downstream flow-water level relationship, establish the discrete equations for the downstream boundary conditions:

[0109]

[0110] in: a N , d N 、e N For discrete coefficients, , , , The initial water level at the downstream boundary section. This represents the flow rate at the downstream boundary section at the initial moment.

[0111] S14. The hydrodynamic equation set composed of the discrete equations in step S13 is calculated iteratively using the chasing method, and the dynamic response of water level and flow rate at each cross-section of the channel over time is output.

[0112] In an optional embodiment of the present invention, the present invention employs a chasing method to iteratively solve the hydrodynamic equations consisting of the discrete equations of the continuity equation, the discrete equations of the momentum equation, the discrete equations of the internal boundary, the discrete equations of the upstream boundary conditions, and the discrete equations of the downstream boundary conditions in the Saint-Venant equations system, and outputs Q at each time step. i and Z i The value is the dynamic response of water level and flow rate at each cross-section of the channel over time.

[0113] S2. Determine typical operating conditions for emergency control.

[0114] In an optional embodiment of the present invention, typical operating conditions include the gate fully closed under design flow, the gate fully closed under medium flow, the gate partially closed under design flow, and the gate partially closed under medium flow.

[0115] S3. Simulate the typical working conditions in step S2 based on the simulation model in step S1, and determine the peak value of the backwater in front of the gate under the typical working conditions.

[0116] S4. Draw a cluster of peak backwater curves based on the peak backwater levels in front of the gate under typical operating conditions in step S3.

[0117] In an optional embodiment of the present invention, based on the simulation results of the above-mentioned typical working conditions, the present invention plots the peak backwater curve ABO of the gate when the gate is fully closed under different initial gate flow rates, and the peak backwater curve ACO of the gate with different gate flow rate amplitudes under the same initial gate flow rate, as shown below. Figure 6 As shown.

[0118] Step S4 includes the following sub-steps:

[0119] S41. Establish a coordinate system with the flow rate variation as the horizontal axis and the peak backwater level in front of the gate as the vertical axis. The horizontal axis is also used to measure the initial flow rate of the gate.

[0120] S42. Plot the peak backwater curves in front of the gate when the gate is fully closed under different initial flow rates of the gate.

[0121] In an optional embodiment of the present invention, the coordinate point A corresponding to the gate fully closed under the design flow rate and the coordinate point B corresponding to the gate fully closed under the medium flow rate are determined in Excel. Using the origin O, coordinate point A, and coordinate point B as sample points, a quadratic polynomial trend line ABO with an intercept of 0 is drawn.

[0122] S43. Plot the peak backwater curves for different gate flow amplitudes under the same initial gate flow.

[0123] In an optional embodiment of the present invention, the coordinate point C corresponding to the partial closure condition of the gate under the design flow rate is determined in Excel, and a quadratic polynomial trend line ACO with an intercept of 0 is drawn using the coordinate origin O, coordinate point A and coordinate point C as sample points.

[0124] S5. Based on the cluster of peak backwater curves in front of the gate in step S4, determine the range of the peak backwater value in front of the gate during emergency response.

[0125] In an optional embodiment of the present invention, after a sudden event occurs, the present invention can easily and quickly determine the range of the peak backwater level in front of the gate on a pre-plotted cluster of peak backwater level curves. The present invention uses the gate flow rate variation x determined according to emergency response procedures. E Using the x-axis as the abscissa, the minimum peak backwater level y can be determined on the ABO curve. E Determine the peak value of the maximum upstream backwater y on the ACO curve. F , [y E , y F This refers to the range of the peak water level in front of the gate.

[0126] Step S5 includes the following sub-steps:

[0127] S51. Obtain the gate flow rate variation for emergency response.

[0128] S52. Based on the flow rate variation in step S51 and the curve drawn in step S42, determine the minimum peak value of backwater in front of the gate.

[0129] In an optional embodiment of the present invention, the present invention uses the gate flow rate variation x determined by the emergency response procedure. E Using the x-coordinate as the x-coordinate, take point E on the curve ABO and read its y-coordinate. E .

[0130] S53. Based on the flow rate variation in step S51 and the curve drawn in step S43, determine the maximum peak value of the backwater in front of the gate.

[0131] In an optional embodiment of the present invention, the present invention uses the gate flow rate variation x determined by the emergency response procedure. E Using the x-coordinate as the x-coordinate, take point F on the curve ACO and read its y-coordinate. F .

[0132] S6. Based on the cluster of peak water backflow curves in front of the gate in step S4, determine the precise peak water backflow in front of the gate during emergency response.

[0133] In an optional embodiment of the present invention, the present invention determines the precise curve drawing point D, draws the straight line DO, and retrieves data on the straight line DO. x The coordinate is equal to the gate flow rate variation. x E The G point, and read the G point. y coordinates y G This is the precise peak value of the backwater level in front of the sluice gate, such as... Figure 6 As shown.

[0134] Step S6 includes the following sub-steps:

[0135] S61. Based on the initial flow rate of the gate during emergency response and the curve drawn in step S42, determine the precise curve plotting point.

[0136] In an optional embodiment of the present invention, the present invention uses the initial flow rate of the gate. x D The x-axis is used as the coordinate, and point D is taken on the curve ABO. Point D is the precise plotting point.

[0137] S62. Draw the straight line determined by the precise curve drawing point and the origin in step S61.

[0138] In an optional embodiment of the present invention, the present invention draws a straight line DO with the origin O and point D as endpoints.

[0139] S63. Based on the gate flow rate variation during emergency response and the straight line drawn in step S62, determine the precise peak value of the backwater in front of the gate.

[0140] In an optional embodiment of the present invention, the present invention retrieves data on the straight line DO. x The coordinate is equal to the gate flow rate variation. x E The G point, and read the G point. y coordinates y G This is the precise peak value of the backwater level in front of the gate.

[0141] like Figure 7 As shown, this invention provides a schematic diagram with letter markings illustrating an embodiment of a method for estimating the peak backwater level before emergency closure of a gate-controlled channel. In this embodiment, the main canal of the South-to-North Water Diversion Project is 1243 km long, connecting the Danjiangkou Reservoir upstream and the Huinanzhuang Pumping Station downstream. The internal boundary is defined by a dimensionless gate flow formula. The section from the Tanghe Sluice Gate to the Fangshuihe Sluice Gate is 25 km long, with a bottom slope of 1 / 25000, a side slope of 1:2.5, and a design flow rate of 130 m³ / s. 3 / s. Typical operating conditions include: design flow rate 130 m³ / s. 3 / s Lower discharge river control gate fully closed, medium flow 70 m³ / s3 / s Lowering the water flow through the fully closed control gate, with a design flow of 130 m³ / s. 3 / s Lower discharge channel control gate partially closed, medium flow 70 m³ / s 3 / s Lower discharge canal control gate partially closed. In the event of an emergency, the initial flow rate of the discharge canal control gate is 90 m³ / s. 3 / s, according to the emergency response procedures, the gate flow rate needs to be reduced by 50 m³ / s. 3 / s. A cluster of peak backwater curves upstream of the control gate of the release channel is pre-plotted. Based on the initial gate flow rate and gate flow rate variation at the time of the emergency, the peak backwater range and precise value upstream are directly read from the cluster of curves. Using the method of this invention, the corresponding trend line formulas in this embodiment are obtained as yABO = 1E-05x² + 0.0049x and yACO = -2E-05x² + 0.0086x, with the gate flow rate variation x determined by the emergency response procedures. E =50 m 3 / s is the x-coordinate. Point E is located on the curve ABO, and its y-coordinate is read. E =0.271, take point F on the curve ACO and read its ordinate y. F =0.386. [0.271, 0.386] represents the estimated range of the backwater peak. In this embodiment, the initial flow rate of the gate is used. x D =90 m 3 Using / s as the x-axis, point D is taken on the curve ABO, and a straight line DO is plotted, corresponding to the trend line formula yAO = 0.0059x. In this embodiment, the x-coordinate on the straight line DO is equal to the gate flow rate amplitude. x E =50 m 3 / s G point, and read G point y coordinates y G =0.295m, which is the precise peak value of the backwater in front of the gate.

[0142] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for estimating the peak backwater level before emergency closure of a gate-controlled channel, characterized in that, Includes the following steps: S1. Construct a one-dimensional non-steady flow simulation model of the channel; S2. Determine typical operating conditions for emergency control; S3. Simulate the typical working conditions in step S2 based on the simulation model in step S1, and determine the peak value of the backwater in front of the gate under the typical working conditions. S4. Draw a cluster of peak backwater curves in front of the gate based on the peak backwater value of the typical working conditions in step S3. S5. Based on the cluster of peak water backflow curves in front of the gate in step S4, determine the range of the peak water backflow during emergency response. S6. Based on the cluster of peak backwater curves in front of the gate in step S4, determine the precise peak backwater value in front of the gate during emergency response. Step S1 includes the following sub-steps: S11. Obtain the channel structure dimensions and hydraulic parameters; S12. Based on the channel structure size parameters and hydraulic parameters obtained in step S11, establish a set of hydrodynamic equations; S13. Input the initial conditions, upstream boundary conditions and downstream boundary conditions, and use the finite difference method to discretize the hydrodynamic equations established in step S12. S14. The hydrodynamic equation set composed of discrete equations in step S13 is calculated iteratively using the chasing method, and the dynamic response of water level and flow rate at each cross-section of the channel over time is output. The typical operating conditions include the gate fully closed under the design flow rate, the gate fully closed under the medium flow rate, the gate partially closed under the design flow rate, and the gate partially closed under the medium flow rate. Step S4 includes the following sub-steps: S41. Establish a coordinate system with the flow rate variation as the horizontal axis and the peak backwater level in front of the gate as the vertical axis. The horizontal axis is also used to measure the initial flow rate of the gate. S42. Plot the peak backwater curves in front of the gate when the gate is fully closed under different initial flow rates of the gate. S43. Plot the peak backwater curves for different gate flow amplitudes under the same initial gate flow rate; Step S5 includes the following sub-steps: S51. Obtain the gate flow rate variation for emergency response; S52. Determine the minimum peak backwater level in front of the gate based on the flow rate variation in step S51 and the curve drawn in step S42. S53. Determine the maximum peak value of backwater in front of the gate based on the flow rate variation in step S51 and the curve drawn in step S43. Step S6 includes the following sub-steps: S61. Determine the precise curve plotting point based on the initial flow rate of the gate during emergency response and the curve drawn in step S42. S62. Draw the straight line determined by the precise curve drawing point and the origin in step S61. S63. Based on the gate flow rate variation during emergency response and the straight line drawn in step S62, determine the precise peak value of the backwater in front of the gate.

2. The method for estimating the peak water backlog before emergency closure of a gate-controlled channel according to claim 1, characterized in that, Step S12 includes the following sub-steps: S121. Based on the Saint-Venant equations, which consist of the continuity equation and the momentum equation, establish the hydrodynamic equations for the channel section: in: A For the water flow area, t Using time as the coordinate, Q For traffic, x For spatial coordinates, Let g be the lateral inflow rate per unit length of the channel, and g be the acceleration due to gravity. z For water level, n The roughness coefficient, R The hydraulic radius; S122. Based on the dimensionless formula for gate flow, establish the hydrodynamic equations for the control gate section: in: , The unit width flow rate of the gate. This represents the opening degree of the gate. and An empirical coefficient related to gate type and flow rate. The difference in water level between the upstream and downstream sides of the sluice gate. , The water level upstream of the sluice gate. This refers to the water level downstream of the sluice gate.

3. The method for estimating the peak water backlog before emergency closure of a gate-controlled channel according to claim 2, characterized in that, Step S13 includes the following sub-steps: S131. Using the Preissmann discretization scheme, calculate the variables and their partial derivatives with respect to time and space in the Saint-Venant equations. The calculation formula is as follows: in: This is the original equation of the Saint-Venant system of equations. These are the discrete equations of the Saint-Venant equations. For time weighting coefficients, Spatial weighting coefficient, j For process distance The x-axis represents time. In a rectangular grid formed by the vertical coordinates, parallel to s The straight line on the axis Position numbering on the axis i To be parallel to t The straight line on the axis s Position numbering on the axis For spatial step size, For time step; S132. Based on the partial derivatives calculated in step S131, establish the discrete equations for the continuity equations in the Saint-Venant equation system: in: , B The width of the water surface. B M For grid eccentricity points in the Preissmann discrete scheme M The width of the water surface at the cross-section, i.e., the subscript M Indicates in M Values ​​are taken at the cross-section. , , , ; S133. Based on the partial derivatives calculated in step S131, establish the discrete equations of the momentum equation in the Saint-Venant equation system: in: , , , , subscript in the formula z The independent variable representing the partial derivative is z That is, the water level; S134. Using the water level and flow rate at each discrete cross-section of the channel at the initial moment as the initial conditions for the spatiotemporal discrete hydrodynamic equations, establish the upstream boundary condition discrete equations based on the inflow rate of the channel: in: a 0、 b 0 and e 0 represents the coefficient of variation. The initial water level at the upstream boundary section. The initial flow rate at the upstream boundary section; S135. Based on the downstream flow-water level relationship, establish the discrete equations for the downstream boundary conditions: in: a N , d N 、e N For discrete coefficients, The initial water level at the downstream boundary section. This represents the flow rate at the downstream boundary section at the initial moment.

4. The method for estimating the peak water backlog before emergency closure of a gate-controlled channel according to claim 1, characterized in that, In step S42, a quadratic polynomial trend line with an intercept of 0 is drawn using the origin, the coordinate points corresponding to the gate fully closed under the design flow rate, and the coordinate points corresponding to the gate fully closed under the medium flow rate.

5. The method for estimating the peak water backflow before emergency closure of a gate-controlled channel according to claim 1, characterized in that, In step S43, a quadratic polynomial trend line with an intercept of 0 is drawn using the origin of the coordinate system, the coordinate points corresponding to the fully closed gate condition under the design flow rate, and the coordinate points corresponding to the partially closed gate condition under the design flow rate.

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