A method, device and medium for calculating dam-break flow process of small and medium-sized reservoirs

Abstract

This invention discloses a method, equipment, and medium for calculating the flow process of dam failure in small and medium-sized reservoirs. The method includes: inputting the reservoir's water level-storage capacity curve, water level-discharge curve, and inflow hydrograph; initializing model parameters; using the dam failure initiation time as a dividing line: before the initiation time, the discharge flow is calculated using the inflow hydrograph, water level-storage capacity curve, and water level-discharge curve; after the initiation time, the total discharge flow is calculated by combining the discharge from the spillway and the breach. This invention allows for arbitrary selection of the dam failure initiation time, simulating the actual operation of the reservoir. It can simulate both the normal discharge from the reservoir via the spillway before the initiation time and the combined discharge from the spillway and the breach after the initiation time. Furthermore, by considering the total discharge from the spillway and the breach during dam failure—that is, the combined discharge from the spillway and the breach—the calculation results are more reasonable and accurate.

Description

Technical Field

[0001] This invention relates to the field of flood control safety data processing technology for water conservancy projects, specifically to a method, equipment, and storage medium for calculating the dam break flow process of small and medium-sized reservoirs. Background Technology

[0002] The safe operation of reservoirs is an important prerequisite for ensuring regional water security. However, due to subjective and objective reasons such as aging reservoir projects, imperfect supervision systems, inadequate management measures, and extreme rainfall, reservoir dam failures still occur from time to time. Therefore, calculating the dam failure flow rate is an important prerequisite for carrying out flood risk management and formulating regional safety measures.

[0003] Currently, when calculating dam-break flows, on the one hand, the peak dam-break flow is mostly calculated using empirical formulas and treated as an instantaneous dam failure. However, earth-rock dams are different from concrete dams; their failure mode should be gradual. After obtaining the peak dam-break flow, the dam-break flow process is directly determined using empirical curves. On the other hand, when calculating dam-break flows, only the peak flow of the reservoir's inflow process is used as the input, ignoring the essential property of the inflow changing over time and failing to consider the inflow situation at different times. This results in incorrect physical meaning and unreasonable results.

[0004] Furthermore, the method does not consider that the discharge flow of the flood discharge facility should be part of the dam failure flow in the event of a dam failure. At the same time, the timing of the dam failure cannot be dynamically changed. Therefore, it is necessary to develop a highly applicable method for calculating the dam failure flow process.

[0005] Regarding methods for calculating reservoir dam break flow, the peak flow is often calculated using empirical formulas, and the dam is treated as an instantaneous failure. After obtaining the peak flow, the dam break flow process is directly determined using empirical curves. For example, in the prior art patent CN114004003A, "A numerical simulation method for reservoir dam break floods applicable to complex urban underlying surfaces," the dam is an earth-rock dam, and the calculation is performed using an instantaneous failure method. Alternatively, in the prior art patent CN120430244B, "A two-dimensional flood simulation method, equipment, and medium for continuous dam break of cascade reservoirs," the dam break flow process is determined using empirical curves after obtaining the peak flow. Or, in the paper "Research on dam break floods and their evolution based on DB-IWHR and HEC-RAS models," the upstream river inflow, i.e., the reservoir inflow, is treated as a constant and substituted into the water balance equation to solve for the dam break flow process.

[0006] However, for reservoirs, the inflow process can be obtained by calculating the runoff generation and confluence of the controlled watershed. When calculating the dam break flow, the inflow situation of the reservoir at different times should be considered, and it obviously cannot be regarded as a constant value. The existing methods for calculating the dam break flow of landslide dams only consider the flood discharge flow of the landslide dam breach because there are no flood discharge facilities such as spillways. However, for reservoirs that break, flood discharge facilities such as spillways can still discharge floodwater, and their discharge volume must be considered when calculating the dam break flow.

[0007] Furthermore, the timing of dam failure, i.e. when the dam will break, is not dynamically variable. It is generally believed that the dam will break when the water level reaches the level corresponding to the set operating conditions.

[0008] In summary, the existing technology for calculating the dam-break flow process still has the following shortcomings in practical applications: (1) The peak flow of reservoir dam failure is mostly calculated by empirical formulas and treated as instantaneous failure of reservoir dam, which will lead to a large deviation between the calculation results and the actual situation; (2) After obtaining the peak flow of the dam break, the process line of the dam break flow is determined directly according to the empirical curve method, that is, the process line of the dam break flow changing with time. However, this method does not consider the impact of the dynamic changes of the inflow of water on the dam break process, nor does it reflect the real situation of the change of the reservoir dam break flow. (3) When calculating the dam break flow, only the peak flow of the reservoir inflow process is used as the input for calculating the dam break flow, ignoring the properties of the inflow process line and not considering the inflow situation at different times; (4) In the case of reservoir dam failure, it has not been considered that the flood discharge flow of the reservoir's flood discharge facilities should be part of the dam failure flow; (5) When a reservoir dam breaks, the moment of failure, i.e. when the dam breaks, cannot be dynamically changed.

[0009] Therefore, this application proposes a method for calculating the dam break flow process of small and medium-sized reservoirs to solve the above-mentioned technical problems. Summary of the Invention

[0010] The main objective of this invention is to provide a method for calculating the dam break flow process of small and medium-sized reservoirs, so as to solve the technical problems mentioned in the background art.

[0011] The present invention solves the above-mentioned technical problems by adopting the following technical solutions: A method for calculating the dam-break flow process of small and medium-sized reservoirs, executed by computer equipment, includes the following steps: Step S1. Input the reservoir water level-storage capacity curve, water level-discharge curve, and reservoir inflow process line (inflow process) to determine the reservoir's initial regulation water level; Step S2. Initialize the breach parameters, broad-crested weir parameters, erosion parameters, roughness coefficient / riverbed roughness n, dam material parameters, and breach hyperbola model parameters of the model; Step S3. Use the time of collapse initiation as the dividing line: Before the moment of collapse, the reservoir discharged water normally through the flood discharge facilities, including the spillway. The discharge flow rate was calculated from the inflow process line, the water level-storage capacity curve, and the water level-discharge curve. After the dam breaks, the reservoir discharges water through the spillway and the breach, and the total discharge flow is calculated. Different dam breaks can be set to allow the reservoir to break at any time and its flow process line to be calculated.

[0012] Preferably, in the initialization model parameters: The breach parameters include the initial breach width, the initial breach bottom elevation, the breach end bottom elevation, the breach development aspect ratio, and the dam initiation time. The initial breach bottom elevation is determined based on the reservoir water level before the dam breach, and the breach end bottom elevation is selected from the reservoir dead water level, i.e., the breach is considered to stop at the dead water level. In addition, the initial breach width can be determined by trial calculation, the breach development aspect ratio can be assumed to be 1, and the dam initiation time can be any value. The parameters of the broad-crested weir include the broad-crested weir flow coefficient, the lateral contraction coefficient, and the tailrace ratio; The erosion parameters include the initiation flow velocity, the initiation shear stress, and the scour coefficient of the breached soil, which are used to calculate the erosion rate of the breached soil. The dam material parameters include cohesion, internal friction angle, dam material unit weight, and, according to Rankine's earth pressure theory, initial breach angle. ,in , , This was confirmed by reviewing the approved reports, including the preliminary design and safety assessment of the reservoir. The parameters of the hyperbolic breach model are determined by the dam material parameters and are used to calculate the slope inclination angle of the breach.

[0013] Preferably, the flood control calculation equation for the discharge flow of the reservoir through the flood discharge facilities before the initiation of the breach in step S3 is set as follows:

[0014] in, , Time periods The initial and final inbound flow rates , Time periods Initial and final outbound flow rates , Time periods The initial and final reservoir capacity.

[0015] Preferably, in step S3, the total discharge flow of the reservoir after the breach initiation time is set as the sum of the discharge flow of the flood discharge facility and the breach flow, wherein the discharge flow of the flood discharge facility is calculated based on the reservoir water level-discharge curve; the calculation method for the breach discharge flow is as follows: Initialize the starting flow velocity, assume parameters such as the initial breach size, and predict the breach characteristics and flow characteristics through specified properties including flow depth, shear stress, and dam material. Finally, obtain the breach flow process line and breach development process line during the dam breach process. When the bottom elevation of the breach reaches the set end bottom elevation, the program stops iterative calculation.

[0016] Preferably, the method for calculating the flow rate at the breach after the initiation time in step S3 specifically includes: Initial startup flow rate Given a flow rate increment The average flow velocity was calculated. The calculation formula is:

[0017] When water flows from the reservoir into the breach, there is a drop in water level, which decreases from H to h, i.e.:

[0018] in, For the tailwater ratio, here we take... , The reservoir water level, The ulcer is deep. The bottom elevation of the breach; Without considering the water flow velocity in the reservoir and the head loss at the inlet section, the flow velocity at the breach section... The calculation formula is as follows:

[0019] Where Q is the breach flow rate and B is the breach width. ,coefficient , and These are the flow coefficient and the lateral contraction coefficient, respectively; recommended values ​​should be used. =0.36, =0.9; When the downstream tailwater level is high, the inundation effect must be considered, therefore a coefficient is introduced. It can be derived from empirical formulas. ; then Inside, the reservoir water level from Change to The bottom elevation of the breach is determined by Change to Then the average flow velocity at this time The calculation process is as follows:

[0020] For the reservoir water level during the time period The original quantity of internal change, The elevation of the breach bottom in the time period The original quantity of internal change; Constructing the algebraic difference of change , and Time periods The specific formulas for calculating the changes in the bottom elevation of the breach and the changes in the reservoir water level are as follows:

[0021] The water balance governing equations are further constructed as follows:

[0022] Therefore, it exists:

[0023]

[0024] in, The average inbound flow rate should be determined based on the inbound flow rate process line; specifically, based on... Water flow rate at all times and Water flow rate at all times The average value is determined; The average discharge capacity of the reservoir's flood discharge facilities (such as spillways and emergency spillways) is specifically calculated based on the water level-discharge relationship. Discharge rate of flood discharge facilities at all times and Discharge rate of flood discharge facilities at all times And then and The average value is used to determine this.

[0025] Clearly, the water balance governing equation takes the inflow process of the reservoir as the input for calculating the dam-break flow, rather than just the fixed value of the peak flow of the inflow process. Furthermore, when considering the dam break, the dam-break flow consists of the discharge flow of the reservoir's flood discharge facilities and the breach flow.

[0026] Preferably, the calculation process for the total breach discharge flow and downstream flow in step S3 is as follows: A hyperbolic erosion model is constructed based on the relationship curve between erosion rate and shear stress as a soil erosion model, which has the following characteristics:

[0027] in:

[0028] In the formula, Soil erosion rate, The depth of the breach scour. The time for the breach to be eroded. For shear stress The function, The calculation is performed by substituting the average flow velocity at the beginning and end of the breach, where γ is the specific gravity of water. J For the slope, Let R be the roughness coefficient and B be the hydraulic radius. When the downstream channel width B is greater than the average flow depth h, the hydraulic radius R can be approximated as h. Then, substituting the algebraic variation and the hyperbolic erosion model into the water balance governing equation, the problem is eliminated. and have to:

[0029] in:

[0030]

[0031]

[0032]

[0033] In the formula, The depth of the breach scour. For the reservoir capacity; When 0.985≤L≤1.015, Δz should be calculated using Taylor series expansion.

[0034]

[0035] Finally, the calculations based on the above water balance governing equations are as follows: , The reservoir water level and breach bottom elevation can be calculated for the next iteration:

[0036]

[0037] The time interval of this iteration of breach erosion :

[0038] In the calculation, it is assumed that the lateral expansion equals the incision depth, i.e., the aspect ratio of the breach development is 1. For the entire breach cross-section, we have:

[0039] The ulcer width B develops as follows:

[0040] In the formula, The initial breach width, The width at the end of the breach. The initial breach bottom elevation, The bottom elevation at the end of the breach. The initial breach angle; The slope inclination angle of the breach can be calculated and determined based on the breach expansion coefficient 1 and breach expansion coefficient 2, i.e., the breach hyperbolic model proposed in the "Dam Break Flood Analysis DB-IWHR2018 User Manual". Finally, the breach flow rate of the broad-crested weir and the flow rate of the flood discharge facility can be obtained from the reservoir water level and breach bottom elevation generated in each iteration. Total outflow The sum of the two:

[0041] in, The width of the ulcer. and These are the reservoir water level and the bottom elevation of the breach, respectively. The time interval of iterative breach erosion The breach flow process line can be obtained from the total outflow, which is the process of the reservoir breach flow changing over time.

[0042] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0043] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0044] As can be seen from the above technical solution, the present invention provides a method for calculating the dam-break flow process of small and medium-sized reservoirs. Compared with the prior art, the present invention has the following advantages: 1. This invention treats the failure of earth-rock dams as a gradual failure and determines the peak flow and process curve of the failure flood based on hydraulic equations. Its calculation process is reasonable and the final calculation results are more in line with reality.

[0045] 2. By using the reservoir inflow process line as one of the model input conditions, this invention fully considers the inflow situation at different time periods, and can more accurately and quantitatively calculate the reservoir dam failure flow.

[0046] 3. This invention can arbitrarily select the initiation time of reservoir dam failure and simulate the actual operation process of the reservoir. It can simulate the normal discharge of water from the reservoir through the flood discharge facilities before the initiation time, and it can also simulate the discharge of water from the reservoir's flood discharge facilities and the breach together after the initiation time.

[0047] 4. In the event of a dam failure, this invention considers the total discharge flow from the reservoir spillway and the breach, i.e., the discharge is carried out by both the reservoir spillway and the breach, thus making the calculation results more reasonable and accurate.

[0048] It should be understood that the descriptions in this section are not intended to identify key or essential features of embodiments of the invention, nor are they intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Of course, implementing any product of the invention does not necessarily require achieving all of the advantages described above simultaneously. Attached Figure Description

[0049] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall process of the present invention; Figure 2 This is a schematic diagram of the breach bottom elevation and reservoir water level change process under the design flood of the reservoir in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the changes in breach flow and total discharge flow under reservoir design flood conditions in an embodiment of the present invention. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] For details in the embodiments, please refer to Figures 1 to 3 .

[0052] like Figure 1As shown in the embodiment of the present invention, the method for calculating the dam-break flow process of small and medium-sized reservoirs includes the following steps: Step 1: Input the reservoir water level-capacity curve, water level-discharge curve, and reservoir inflow process line (inflow process) to determine the reservoir's initial regulation water level.

[0053] The input interface for the reservoir design flood dam break discharge calculation model, including the water level-reservoir capacity curve, is shown in Table 1 below: Table 1: Curve Input Interface Table

[0054] Step 2: Initialize model parameters as follows: (1) Breach parameters: initial width of the breach Initial bottom elevation of the breach The bottom elevation of the breach ended The horizontal and vertical ratio of the breach development, and the moment when the dam body begins to collapse; Generally, the initial bottom elevation of the breach can be determined based on the reservoir water level before the dam breach, and the bottom elevation of the breach end is selected from the dead water level of the reservoir, that is, the breach is considered to stop when the breach reaches the dead water level. The initial width of the breach can be determined through trial calculations, the longitudinal-to-transverse ratio of the breach development can be assumed to be 1, and the moment of dam failure can be any value. (2) Broad-crested weir parameters: Recommended values ​​are adopted, and the broad-crested weir flow coefficient is used. Lateral shrinkage coefficient tailwater ratio ; (3) Erosion parameters: Start-up flow rate Initiate shear stress erosion coefficient of the breached soil and This value is used to calculate the erosion rate of the breached soil. The recommended value from the "DB-IWHR2018 User Manual for Dam Break Flood Analysis" is adopted here. , , ; (4) Roughness coefficient: riverbed roughness ; (5) Dam material parameters: cohesion internal friction angle dam material unit weight According to Rankine's earth pressure theory, the initial breach angle is... ,in , , This was confirmed by reviewing the approved reports, including the preliminary design and safety assessment of the reservoir. (6) Parameters of the hyperbolic breach model: breach expansion coefficient 1 and breach expansion coefficient 2, used to calculate the slope angle of the breach. It is determined by calculation of the dam body material parameters.

[0055] The model parameter input interface is shown in Table 2 below: Table 2: Model Parameter Input Interface

[0056] Step 3: Using the moment of initiation of the breach as the dividing line, before the moment of initiation of the breach, the reservoir discharges floodwater normally through the spillway and other flood discharge facilities. The discharge flow rate is obtained by flood regulation calculation based on the inflow process line, the water level-storage capacity curve, and the water level-discharge curve. After the moment of initiation of the breach, the reservoir discharges floodwater through the spillway and other flood discharge facilities and the breach. The total discharge flow rate should be equal to the sum of the discharge flow rate of the flood discharge facilities and the discharge flow rate of the breach.

[0057] By setting different initiation and failure times, the dam can be made to break at any given moment, and its flow process curve can be calculated. (1) Before the moment of collapse, the reservoir's flood discharge facilities discharge water normally. The discharge rate is calculated based on the reservoir's initial regulating water level, using the inflow hydrograph, water level-storage capacity curve, and water level-discharge curve. The basic equation for the flood regulation calculation is:

[0058] in, , Time periods The initial and final inbound flow rates , Time periods Initial and final outbound flow rates , Time periods The initial and final reservoir capacity.

[0059] (2) After the breach, the total discharge should be the sum of the discharge from the spillway and other flood discharge facilities and the breach discharge. The discharge from the spillway and other flood discharge facilities is calculated based on the reservoir water level-discharge curve. The method for calculating the breach flow rate here is as follows: The basic idea for calculating the breach flow is as follows: Initialize the starting flow velocity Vc, assume initial breach size and other parameters, and predict breach characteristics and flow characteristics through properties such as flow depth, shear stress, and dam material, thereby obtaining the breach flood hydrograph and breach development hydrograph during the dam breach process. When the breach bottom elevation develops to the set end bottom elevation, the program stops iterative calculation.

[0060] Initial startup flow rate Given a flow rate increment The average flow velocity was calculated. The calculation formula is:

[0061] When water flows from the reservoir into the breach, there is a drop in water level, which decreases from H to h, i.e.:

[0062] in, For the tailwater ratio, here we take... , The reservoir water level, The ulcer is deep. This is the elevation of the breach bottom.

[0063] Assuming the water flow velocity in the reservoir and the head loss at the inlet section are negligible, then the flow velocity at the breach section... have: (4) Where Q is the breach flow rate and B is the breach width. ,coefficient , and These are the flow coefficient and the lateral contraction coefficient, respectively; recommended values ​​should be used. =0.36, =0.9.

[0064] When the downstream tailwater level is high, the inundation effect is considered, and a coefficient is introduced. It can be derived from empirical formulas. .

[0065] then Inside, the reservoir water level from Change to The bottom elevation of the breach is determined by Change to Then the average flow velocity at this time The calculation process is as follows:

[0066] For the reservoir water level during the time period The original quantity of internal change, The elevation of the breach bottom in the time period The original quantity of internal change.

[0067] Constructing the algebraic difference of change , and Time periods The specific formulas for calculating the changes in the bottom elevation of the breach and the changes in the reservoir water level are as follows:

[0068] The water balance governing equations are further constructed as follows:

[0069] Therefore, it exists:

[0070]

[0071] in, The average inbound flow rate should be determined based on the inbound flow rate process line; specifically, based on... Water flow rate at all times and Water flow rate at all times The average value is determined; The average discharge capacity of the reservoir's flood discharge facilities (such as spillways and emergency spillways) is specifically calculated based on the water level-discharge relationship. Discharge rate of flood discharge facilities at all times and Discharge rate of flood discharge facilities at all times And then and The average value is used to determine this.

[0072] Clearly, the water balance governing equation takes the inflow process of the reservoir as the input for calculating the dam-break flow, rather than just the fixed value of the peak flow of the inflow process. Furthermore, when considering the dam break, the dam-break flow consists of the discharge flow of the reservoir's flood discharge facilities and the breach flow.

[0073] The soil erosion model, i.e., the relationship curve between erosion rate and shear stress, adopts a hyperbolic erosion model, which has:

[0074] in:

[0075] In the formula, Soil erosion rate, The depth of the breach scour. The time for the breach to be eroded. For shear stress The function, The calculation is performed by substituting the average flow velocity at the beginning and end of the breach, where γ is the specific gravity of water. J For the slope, Let R be the roughness coefficient and B be the hydraulic radius. When the downstream channel width B is greater than the average flow depth h, the hydraulic radius R can be approximated as h. Then, substituting the algebraic variation and the hyperbolic erosion model into the water balance governing equation, the problem is eliminated. and have to:

[0076] in:

[0077]

[0078]

[0079]

[0080] In the formula, The depth of the breach scour. This refers to the reservoir's storage capacity.

[0081] When 0.985≤L≤1.015, Δz should be calculated using Taylor series expansion.

[0082]

[0083] Finally, the calculations based on the above water balance governing equations are as follows: , The reservoir water level and breach bottom elevation can be calculated for the next iteration:

[0084]

[0085] The time interval of this iteration of breach erosion :

[0086] In the calculation, it is assumed that the lateral expansion equals the incision depth, i.e., the aspect ratio of the breach development is 1. For the entire breach cross-section, we have:

[0087] The ulcer width B develops as follows:

[0088] In the formula, The initial breach width, The width at the end of the breach. The initial breach bottom elevation, The bottom elevation at the end of the breach. The initial breach angle; The slope inclination angle of the breach can be calculated and determined based on the breach expansion coefficient 1 and breach expansion coefficient 2, i.e., the breach hyperbolic model proposed in the "Dam Break Flood Analysis DB-IWHR2018 User Manual". Finally, the breach flow rate of the broad-crested weir and the flow rate of the flood discharge facility can be obtained from the reservoir water level and breach bottom elevation generated in each iteration. Total outflow The sum of the two:

[0089] in, The width of the ulcer. and These are the reservoir water level and the bottom elevation of the breach, respectively. The time interval of iterative breach erosion The breach flow process line can be obtained from the total outflow, which is the process of the reservoir breach flow changing over time.

[0090] Furthermore, at this point, the program termination condition also exists: the bottom elevation of the breach. The development reached the set breach end elevation. .

[0091] In summary, this method clearly treats earth-rock dam breaches as gradual breaches, abandons the limitations of a single empirical formula, and derives and determines the peak flow and flow process line of the breach based on core equations such as hydraulics. Its calculation process is more theoretically supported and reasonable, and can accurately reflect the gradual evolution characteristics of the widening and deepening of the breach in earth-rock dams. Moreover, the final calculation results are more consistent with the actual dam breach conditions of reservoirs.

[0092] Meanwhile, this method also fully considers the dynamic changes in inflow, enhancing the comprehensiveness of the calculation. Compared with existing methods, it can use the inflow process line obtained from the runoff generation and confluence calculation of the reservoir control basin as one of the core input conditions of the model, and comprehensively incorporate the inflow situation at different time periods, thereby facilitating a more accurate quantitative calculation of the reservoir dam failure flow and effectively making up for the shortcomings of existing technologies that ignore the dynamic changes in inflow.

[0093] Furthermore, this method can dynamically adjust the initiation and failure time, closely matching the actual operation scenario of the reservoir. Specifically, in practical applications, it supports arbitrary selection of the initiation and failure time of the reservoir dam failure, and can completely simulate the entire actual operation process of the reservoir: before the initiation and failure time, the reservoir discharges floodwater normally through spillways and other flood discharge facilities to maintain normal operation; after the initiation and failure time, the reservoir's flood discharge facilities and the breach work together to discharge floodwater, accurately restoring the real operation scenario before and after the dam failure, thereby improving the practicality and scenario adaptability of the method.

[0094] In a further embodiment, the water level-storage capacity curve, water level-discharge curve, 50-year return period design inflow process, and 1000-year return period check inflow process are obtained from the preliminary design report of the reinforcement project of Reservoir A. The initial adjustment water level is 50.96m, and the design water level is 52.13m (1985 National Elevation System). In the implementation of this further embodiment, the design standard flood, i.e., encountering a 50-year return period inflow process, is taken as an example. The water level-storage capacity curve, water level-discharge curve, and 50-year return period design inflow process of Reservoir A are shown in Tables 3-5 below: Table 3: Water Level-Capacity Curve Data for Reservoir A

[0095] Table 4: Water Level-Discharge Curve Data for Reservoir A

[0096] Table 5: Data on the Design Inflow Process of Reservoir A (50-Year Return Period)

[0097] Input the water level-reservoir capacity curve, water level-discharge curve, and 50-year return period design inflow process into the model, and initialize the model parameters as follows: (1) Breach parameters: initial width of the breach Initial bottom elevation of the breach The bottom elevation of the breach ended The breach development aspect ratio and the dam initiation time are selected here. The initiation time is when the reservoir water level reaches the design water level of 52.13m, which is the 16th hour of the incoming water. The initial bottom elevation of the breach is taken as 52m. The dead water level of Reservoir A is 44.81m. The bottom elevation of the breach end is taken as 45m. The breach development aspect ratio is 1. The initial width of the breach is initialized to 10m.

[0098] (2) Broad-crested weir parameters: Recommended values ​​are adopted, and the broad-crested weir flow coefficient is used. =0.36, lateral shrinkage coefficient =0.9, tailwater ratio =0.8.

[0099] (3) Erosion parameters: Based on the recommended values ​​in the "Dam Break Flood Analysis DB-IWHR2018 User Manual", the starting flow velocity was adopted. Initially set at 2.4 m / s, initiate shear stress. erosion coefficient of the breached soil and This is used to calculate the erosion rate of the breached soil; the flow rate is started here. Determine whether it is suitable through trial calculations.

[0100] (4) Roughness coefficient: riverbed roughness Take 0.03.

[0101] (5) Dam material parameters: cohesion internal friction angle dam material unit weight According to Rankine's earth pressure theory, the initial breach angle is... This section determines the material parameters of the reservoir dam body, specifically the cohesion, based on the preliminary design report of the reinforcement project for Reservoir A. =40Kpa, internal friction angle =15°, dam material unit weight =19.5kN / m 3 Initial breach angle =127.5°.

[0102] (6) Breach hyperbolic model parameters: The breach expansion coefficient 1 is determined to be 0.181 and the breach expansion coefficient 2 is 0.016 based on the dam material parameters.

[0103] Then, taking the moment of breach as the dividing line, before the moment of breach, the reservoir discharges floodwater normally through the flood discharge facilities, and its discharge flow is obtained by flood regulation calculation based on the inflow process line, water level-storage capacity curve and water level-discharge curve; after the moment of breach, the reservoir discharges floodwater through the flood discharge facilities and the breach, and its total discharge flow should be equal to the sum of the flood discharge flow of the flood discharge facilities and the flow of the breach.

[0104] The breach bottom elevation, breach width, breach discharge, spillway discharge, and total downstream discharge of Reservoir A can then be calculated. The specific calculation results are shown in Table 6 below: Table 6: Calculation Results of Reservoir Breach Discharge

[0105] As shown in the table above, the dam failure of Reservoir A occurred at the 16th hour of the incoming water process. Before this time, the reservoir did not experience a dam failure, and the spillway and other flood discharge facilities discharged water normally, with the spillway discharge increasing from 0 to 112.22 m³. 3 At a rate of / s, the reservoir water level rose from 50.96m to 52.13m, reaching the design water level, at which point a dam breach occurred. After the dam breach, a rectangular breach initially formed, with a bottom elevation of 52m and an initial width of 10m. The breach flood then eroded the dam structure, and the breach continued to expand. At this point, the total discharge flow was divided into two parts: the spillway discharge flow and the breach discharge flow, with the peak breach discharge flow reaching 940.43m³. 3 / s. Finally, when the bottom elevation of the breach reaches 45m, the scouring stops, and the calculation ends.

[0106] The following diagrams illustrate the changes in the breach bottom elevation and reservoir water level of Reservoir A under the design flood, as well as the changes in the breach discharge and total outflow under the design flood of Reservoir A: Figure 2 and Figure 3 As shown, the initial breach bottom elevation of Reservoir A under the design flood was 52m, and the initial width was 10m. After approximately 2 hours, the breach reached its maximum size, with a breach bottom elevation of 45m and a width of 41.9m. The peak flow rate of the breach and spillway reached 972.8m. 3 / s, and the flow rate dropped to 10m after about 14 hours. 3 It lasts for about 1 second, and then tends to stabilize.

[0107] The water balance analysis results for the calculated flow rate of Reservoir A in case of a dam failure are shown in Table 7 below.

[0108] According to water balance, the difference between the total inflow and the total outflow should equal the change in reservoir capacity, i.e. The relative error of Reservoir A is -0.005%, indicating that the calculation of the dam break flow process of Reservoir A follows the water balance equation.

[0109] Based on the above example of Reservoir A, the dam-break discharge hydrograph was solved, which comprehensively considers: (1) Using the inflow process line of Reservoir A as one of the input conditions of the model, the inflow situation at different time periods is fully considered, instead of just using the peak flow of the inflow process line, so as to more accurately and quantitatively calculate the dam failure flow of the reservoir. (2) The timing of the dam failure can be arbitrarily selected to simulate the actual operation of the reservoir. Before the failure time, the reservoir discharges water normally through the flood discharge facilities. After the failure time, the reservoir discharge facilities and the breach discharge water together.

[0110] (3) When the reservoir dam breaks, the total discharge flow of the reservoir spillway and other flood discharge facilities and the breach is taken into account, which is more reasonable and accurate.

[0111] In summary, this method incorporates the discharge flow of existing flood discharge facilities such as reservoir spillways into the total dam break flow calculation system, clearly defining the discharge of flood discharge facilities as an important component of the dam break flow. This differs from the traditional method that only calculates the discharge at the breach, resulting in a more complete flow composition, more accurate calculation results, and greater practical engineering guidance value.

[0112] In another aspect, the present invention also discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method described above.

[0113] In another aspect, the present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method described above.

[0114] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute any of the methods for calculating the flow rate of small and medium-sized reservoir dam breaks in the above embodiments.

[0115] It is understood that the system provided in the embodiments of the present invention corresponds to the method provided in the embodiments of the present invention, and the explanation, examples and beneficial effects of the relevant content can be referred to the corresponding parts of the above methods.

[0116] This application also provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, communication interface, and memory communicate with each other via the communication bus. Memory, used to store computer programs; The processor, when executing the program stored in memory, implements the above-mentioned method for calculating the dam break flow process of small and medium-sized reservoirs.

[0117] The communication bus mentioned in the above-mentioned electronic devices can be a standard bus for interconnecting peripheral components or an extended industrial standard structure bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc.

[0118] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0119] The memory may include random access memory or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0120] The processors mentioned above can be general-purpose processors, including central processing units, network processors, etc.; they can also be digital signal processors, application-specific integrated circuits, field-programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0121] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, an optical medium, or a semiconductor medium, etc.

[0122] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0123] Furthermore, it should be noted that if any directional indication (such as up, down, left, right, front, back, etc.) is involved in the embodiments of the present invention, the directional indication is only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0124] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, in the embodiments of this invention, "multiple" refers to two or more. Moreover, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

Claims

1. A method for calculating the dam-break flow process of small and medium-sized reservoirs, characterized in that, include: Step S1. Input the reservoir water level-storage capacity curve, water level-discharge curve, and reservoir inflow process line to determine the reservoir's initial regulation water level; Step S2. Initialize the breach parameters, broad-crested weir parameters, erosion parameters, roughness coefficient / riverbed roughness n, dam material parameters, and breach hyperbola model parameters of the model; Step S3. Use the time of collapse initiation as the dividing line: Before the moment of collapse, the reservoir discharged water normally through the flood discharge facilities, including the spillway. The discharge flow rate was calculated from the inflow process line, the water level-storage capacity curve, and the water level-discharge curve. After the breach begins, the reservoir discharges water through its spillway and the breach, calculating the total discharge flow.

2. The method for calculating the dam-break flow process of small and medium-sized reservoirs as described in claim 1, characterized in that, In the initialization model parameters: The breach parameters include the initial breach width, the initial breach bottom elevation, the breach end bottom elevation, the breach development aspect ratio, and the dam breach initiation time. The initial breach bottom elevation is determined based on the reservoir water level before the dam breach, and the breach end bottom elevation is selected from the dead water level of the reservoir. The parameters of the broad-crested weir include the broad-crested weir flow coefficient, the lateral contraction coefficient, and the tailrace ratio; The erosion parameters include the initiation flow velocity, the initiation shear stress, and the scour coefficient of the breached soil, which are used to calculate the erosion rate of the breached soil. The dam material parameters include cohesion, internal friction angle, and dam material unit weight. The parameters of the hyperbolic breach model are determined by the dam material parameters and are used to calculate the slope inclination angle of the breach.

3. The method for calculating the dam-break flow process of small and medium-sized reservoirs as described in claim 1, characterized in that, In step S3, the flood control calculation equation for the discharge flow of the reservoir through the spillway before the moment of collapse is set as follows: in, , Time periods The initial and final inbound flow rates , Time periods Initial and final outbound flow rates , Time periods The initial and final reservoir capacity.

4. The method for calculating the dam-break flow process of small and medium-sized reservoirs as described in claim 1, characterized in that, In step S3, the total discharge flow of the reservoir after the breach initiation time is set as the sum of the discharge flow of the flood discharge facilities and the breach flow. The discharge flow of the flood discharge facilities is calculated based on the reservoir water level-discharge curve. The calculation method for the breach discharge flow is as follows: Initialize the starting flow velocity, assume parameters such as the initial breach size, and predict the breach characteristics and flow characteristics through specified properties including flow depth, shear stress, and dam material. Finally, obtain the breach flow process line and breach development process line during the dam breach process. When the bottom elevation of the breach reaches the set end bottom elevation, the program stops iterative calculation.

5. The method for calculating the dam-break flow process of small and medium-sized reservoirs as described in claim 4, characterized in that, The method for calculating the flow rate at the breach after the initiation of the breach in step S3 specifically includes: Initial startup flow rate Given a flow rate increment The average flow velocity was calculated. The calculation formula is: ; When water flows from the reservoir into the breach, there is a drop in water level, that is: ; in, The tailwater ratio, The reservoir water level, The ulcer is deep. The bottom elevation of the breach; For the flow velocity at the breach cross section The calculation formula is as follows: Where Q is the breach flow rate and B is the breach width. ,coefficient , and These are the flow coefficient and the lateral contraction coefficient, respectively. ; At this time, the average flow velocity The calculation process is as follows: For the reservoir water level during the time period The original quantity of internal change, The bottom elevation of the breach in the time period The original quantity of internal change; Constructing the algebraic difference of change , and Time periods The specific formulas for calculating the changes in the bottom elevation of the breach and the changes in the reservoir water level are as follows: The water balance governing equations are further constructed as follows: Therefore, it exists: in, The average inbound flow rate is based on... Water flow rate at all times and Water flow rate at all times The average value is determined; The average discharge capacity of the reservoir's flood discharge facilities is calculated based on the water level-discharge relationship. Discharge rate of flood discharge facilities at all times and Discharge rate of flood discharge facilities at all times And then and The average value is used to determine this.

6. The method for calculating the dam-break flow process of small and medium-sized reservoirs as described in claim 5, characterized in that, The calculation process for the total discharge flow from a reservoir dam failure in step S3 is as follows: A hyperbolic erosion model was constructed based on the relationship curve between erosion rate and shear stress as a soil erosion model. Then, the variation difference and the hyperbolic erosion model were substituted into the water balance governing equation to eliminate... and ; Calculated from the water balance governing equation , The reservoir water level and breach bottom elevation can be calculated for the next iteration; Finally, the breach flow rate of the broad-crested weir and the flow rate of the flood discharge facility can be obtained from the reservoir water level and breach bottom elevation generated in each iteration. Total outflow The sum of the two: in, The width of the ulcer. and These are the reservoir water level and the bottom elevation of the breach, respectively.

7. The method for calculating the dam-break flow process of small and medium-sized reservoirs as described in claim 1, characterized in that, In step S3, after the breach initiation time, during the calculation of the discharge flow at the breach, the empirical formula is replaced by the empirical formula to calculate the peak flow of the dam breach. After obtaining the peak flow of the dam breach, it is directly determined according to the empirical curve method.

8. The method for calculating the dam-break flow process of small and medium-sized reservoirs as described in claim 6, characterized in that, In step S3, after the moment of initiation of the breach, the peak flow rate of the reservoir inflow process is used as the input instead of the peak flow rate of the reservoir inflow process. The change of the reservoir inflow process flow rate is not considered when calculating the dam breach flow rate.

9. A computer-readable storage medium, characterized in that, The device stores a computer program that, when executed by a processor, causes the processor to perform the steps of the method as described in any one of claims 1 to 8.

10. A computer device, characterized in that, It includes a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the method as described in any one of claims 1 to 8.

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