A method and apparatus for simulation prediction and stability analysis of cracks in spillway dams.

Abstract

This invention discloses a method and apparatus for simulation prediction and stability analysis of cracks in spillway dams, relating to the field of hydraulic engineering, for comprehensive analysis of crack formation and stability prediction. The invention establishes a nonlinear finite element model of downstream facade cracks in the spillway dam section, applies loads such as self-weight, temperature, water pressure, sand pressure, uplift pressure, and valve thrust to the model, and then performs simulation calculations of the entire process of spillway dam construction, impoundment, and operation. Next, it inverts the crack initiation and propagation process of the downstream facade cracks in the spillway dam section, performs corresponding repair treatments on the cracks, and evaluates the state of the cracks after treatment through simulation and analyzes the propagation stability of the cracks. This invention more comprehensively considers various influencing factors, provides more accurate crack formation analysis, and has advantages such as high efficiency, accuracy, high stability, strong operability, and low detection cost.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering, and in particular to a method and apparatus for simulating and predicting cracks and analyzing the stability of spillway dams. Background Technology

[0002] With the continuous development of water conservancy projects, concrete spillway dams, as an important water conservancy facility, are widely used in the regulation and management of water resources. However, during their long-term operation, the dam body often develops cracks due to the influence of various external loads. These cracks not only affect the integrity and safety of the dam body, but may also lead to serious leakage and structural failure. Therefore, accurately analyzing and predicting the causes and development trends of dam surface cracks is particularly important.

[0003] In recent years, crack formation analysis methods based on finite element method (FEM) full-process simulation technology have gradually attracted attention. This method, by establishing a three-dimensional finite element model of the spillway dam and comprehensively considering various loads such as self-weight, temperature, water pressure, and sand pressure, can simulate the formation and propagation process of cracks in a relatively comprehensive manner, providing a scientific basis for the safety assessment of spillway dams.

[0004] While the finite element method (FEM) offers certain advantages in crack analysis, current research on the causes of cracks in dam surfaces remains relatively limited, and most studies employ techniques with inherent limitations. Specifically, traditional crack analysis methods rely heavily on empirical formulas and simple mechanical models, which often fail to adequately account for the heterogeneity of concrete and the complexities of load effects. Furthermore, many studies focus only on the influence of single factors on cracks, lacking in-depth analysis of crack behavior under the combined effects of multiple factors. This one-sided approach not only reduces the accuracy of crack prediction but also results in an incomplete understanding of crack causes. Therefore, a more systematic and precise analytical method is urgently needed to improve the efficiency and reliability of crack cause analysis. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for simulating and predicting cracks in spillway dams and analyzing their stability, in order to achieve a comprehensive analysis of the causes of cracks and predict their stability, addressing all or part of the problems mentioned above.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for simulation prediction and stability analysis of cracks in spillway dams, comprising:

[0008] S1. By pre-setting nonlinear contact elements at the crack locations, a nonlinear finite element model of the downstream facade cracks of the spillway section is established to simulate the cracks in the downstream facade of the spillway section.

[0009] S2. Apply at least two of the following loads to the model: self-weight, temperature, water pressure, sand pressure, uplift pressure, and valve thrust.

[0010] S3. Conduct simulation calculations for the entire process of spillway dam construction, water storage, and operation:

[0011] Based on monitoring data of the construction, water storage and operation of the spillway dam, a nonlinear finite element full-process simulation analysis method is adopted. According to the actual construction progress of the spillway dam, the simulation calculations of the concrete pouring process, hydration heat generation process, hardening process, longitudinal joint grouting process, water cooling, surface insulation measures, air temperature change process and reservoir water level change process are carried out to simulate the temperature field and stress field of the entire process of the spillway dam construction, water storage and operation.

[0012] S4. Based on the simulation calculation results of step S3, with the goal of minimizing the difference between the simulation calculation values ​​and the monitoring data of the temperature and deformation of the spillway dam body, the initiation and propagation process of the downstream facade cracks of the spillway dam section is inverted.

[0013] S5. Based on the analysis results of the crack initiation and propagation process in step S4, the crack is repaired accordingly. The state of the crack after treatment is evaluated through simulation and the propagation stability of the crack is analyzed.

[0014] Furthermore, step S1 includes:

[0015] S1.1 Collect the size and material information of the spillway dam, and use the nonlinear finite element tool to establish a three-dimensional geometric model of the spillway dam;

[0016] S1.2, Contact elements are used to simulate cracks;

[0017] S1.3 The initial strength of the initial crack is the strength of the concrete itself.

[0018] Furthermore, in step S3, the simulated concrete pouring process includes:

[0019] The spillway dam is divided into grids, and each unit is sorted according to the pouring sequence. The corresponding units are activated step by step to simulate the pouring of concrete. The self-weight of the activated unit is used as the load increment. It is set that the concrete of each unit gradually hardens and undergoes creep deformation after pouring, and the heat of hydration is gradually dissipated.

[0020] After each unit of concrete is poured, the time is divided into multiple time intervals, and the temperature field and stress field of the spillway dam are calculated in time sequence for each time step.

[0021] The simulated joint grouting process includes:

[0022] Grouting is performed on the expansion joints between dam sections and between cast blocks in sequence to connect the concrete of the dam sections and blocks into a whole.

[0023] Goodman elements with tensile strength were used to simulate expansion joints, and discontinuous deformation analysis was introduced into the finite element method to simulate the opening and closing state of expansion joints.

[0024] The simulation involves layered, segmented, and skip-unit pouring of concrete, as well as layered and phased joint grouting. It tracks the stress changes, opening and closing processes, and expansion joint opening changes of each Goodman unit. When the relevant grouting area meets the grouting requirements and joint grouting is performed, the current opening of each expansion joint is locked, and this current opening is used as the thickness of the Goodman unit. The Goodman unit is then filled with grouting material, and the corresponding material parameters are set. Tensile and shear strengths are given according to the following formula:

[0025]

[0026] In the formula, i represents the expansion joint identifier, and δ i For the opening of the expansion joint, , respectively, represent the normal and shear stiffness of the expansion joint; E and μ represent the elastic modulus and Poisson's ratio of the grouting material, respectively;

[0027] Simulated water cooling includes:

[0028] The equivalent simulation method is used to simulate the heat carried away by water cooling in order to calculate the concrete temperature;

[0029] Simulated surface insulation includes:

[0030] Surface insulation is simulated by changing the surface heat dissipation coefficient, where the surface heat dissipation coefficient β0 when the concrete surface is exposed is calculated by the following formula:

[0031] β0 = 23.9 + 14.50v n ,

[0032] In the formula, v n Wind speed;

[0033] The surface heat dissipation coefficient β when the concrete surface is covered with insulation board s Calculated by the following formula:

[0034]

[0035] In the formula, h i Let λ be the thickness of insulation board i. i Let i be the thermal conductivity coefficient of the insulation board.

[0036] The simulated water storage operation process includes:

[0037] Before impounding water, temperature and stress field models were established by simulating construction, temperature control, and material hydration and hardening processes. After impounding water began, water pressure was simulated by applying triangular surface loads to the upstream and downstream faces of the spillway dam, and uplift pressure was simulated by applying vertical surface loads to the dam foundation interface. During the impounding process, the temperature boundary conditions of the upstream dam face changed from air temperature boundary conditions to water temperature boundary conditions for the surface of the rising water level, while the water level fluctuation zone alternated between air temperature boundary conditions and water temperature boundary conditions.

[0038] In the simulation calculation of the temperature field and stress field of the spillway dam, the temperature boundary conditions are set according to the measured temperature or the multi-year monthly average temperature, and the influence of solar radiation heat is simulated by adding a temperature increment to the set temperature.

[0039] Furthermore, in step S4, the initiation and propagation process of cracks on the downstream facade of the spillway section is inverted, including the inversion of thermal parameters of the spillway concrete and bedrock, as well as the inversion of mechanical parameters of the spillway concrete and bedrock.

[0040] Furthermore, the inversion of the thermal parameters of the spillway dam concrete and bedrock includes:

[0041] With the goal of minimizing the difference between the simulated values ​​and the monitoring data on the temperature and deformation of the spillway dam body, the thermal conductivity, specific heat, and adiabatic temperature rise parameters of the concrete in different zones of the spillway dam body were obtained through inversion. Specifically, during the simulation calculation, the adiabatic temperature rise during the construction period of the spillway dam body and the temperature recovery after joint grouting were simulated using the following formula:

[0042]

[0043] In the formula, Q(τ) represents the adiabatic temperature rise at the concrete age τ, α1 and α2 are the adiabatic temperature rise parameters of the dam body and joint grouting, respectively; τ is the concrete age; Q1 and Q2 are the final adiabatic temperature rise values ​​of the spillway dam concrete and grouting material, respectively.

[0044] Furthermore, the inversion of the mechanical parameters of the spillway dam concrete and bedrock includes:

[0045] Based on the monitoring data of the deformation of the spillway dam, and using the water pressure components at each measuring point obtained from regression, the finite element simulation analysis method is adopted. Considering only the hydrostatic pressure, the deformation of the dam body under different elastic moduli of concrete is simulated and calculated. The calculated deformation is compared with the water pressure deformation components obtained from the multivariate regression of the deformation monitoring data. With the goal of minimizing the error between the simulation calculation value and the water pressure deformation components, the optimal elastic modulus of the concrete and bedrock of the spillway dam body is determined by inversion.

[0046] In the simulation calculation, the following formula is used to simulate the hardening process of the elastic modulus of concrete:

[0047]

[0048] In the formula, E(τ) and E0 are the elastic modulus and final elastic modulus of the dam concrete at an age of τ, respectively, and α and β are the elastic modulus growth rate parameters of the concrete.

[0049] Furthermore, in step S5, the state of the crack after treatment is evaluated through simulation and the stability under extreme climatic conditions is analyzed.

[0050] Furthermore, the process of evaluating the state of the cracks after treatment through simulation and analyzing their stability under extreme climatic conditions includes:

[0051] Climate data from historically lowest temperature periods were selected as the temperature parameters for simulation. These parameters were used to simulate the crack state during the predetermined normal operation period after crack treatment. By comparing the crack states before and after treatment in winter and summer, the propagation stability of the cracks under different seasonal temperature variations was analyzed.

[0052] The simulation was conducted to examine the crack state after the insulation board was removed and crack treatment was performed in winter, in order to analyze the crack propagation stability under extreme low temperature conditions.

[0053] The present invention also provides a device for simulation prediction and stability analysis of cracks in spillway dams, including a processor and a storage medium. The processor runs a computer program stored in the storage medium to execute the above-described method for simulation prediction and stability analysis of cracks in spillway dams.

[0054] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0055] This invention establishes a detailed nonlinear finite element model, comprehensively considering loads such as self-weight, temperature, water pressure, and sand pressure, to achieve a comprehensive analysis and prediction of crack formation causes. This invention introduces nonlinear contact elements into crack propagation discrimination, more accurately simulating the opening-closing state and propagation process of cracks, and focuses on predicting the state after crack treatment, especially the stability analysis under extreme climatic conditions, providing technical support for the safety management of spillway dams. Compared with traditional methods, this invention can more comprehensively consider various influencing factors, provide more accurate crack formation analysis, and has advantages such as high efficiency, accuracy, high stability, strong operability, and low detection cost. It can effectively guide engineering practice and provide a scientific basis for the safety management of spillway dams. Through this novel technical means, the causes of cracks on the dam surface of spillway dams can be better understood and predicted, providing more reliable technical support for the design, construction, and maintenance of spillway dams. Attached Figure Description

[0056] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0057] Figure 1 This is a flowchart of the method for simulation prediction and stability analysis of cracks in spillway dams proposed in the embodiments of this application.

[0058] Figure 2 This is a simulation diagram of the cracks in the spillway dam in the embodiments of this application.

[0059] Figure 3 This is a comparison diagram of summer and winter cracking during the construction period of the spillway dam in this application embodiment.

[0060] Figure 4 This is a line diagram showing the crack opening process at an elevation of 353m in the spillway dam in an embodiment of this application.

[0061] Figure 5 This is a graph showing the measured temperature data of the spillway dam in the embodiments of this application.

[0062] Figure 6 These are before-and-after comparison images of the winter crack grouting treatment of the spillway dam in this application embodiment.

[0063] Figure 7 This is a diagram showing the state of the cracks in the spillway dam after summer crack grouting treatment, as described in this application embodiment.

[0064] Figure 8 This is a diagram showing the crack state of the spillway dam after the insulation board was removed, as described in this application embodiment. Detailed Implementation

[0065] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0066] Any feature disclosed in this specification (including any appended claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0067] To address the issues of analyzing the causes and assessing the stability of cracks in spillway dams in water conservancy projects, this application proposes a method for simulating and predicting cracks in spillway dams, aiming to overcome the limitations of existing technologies in analyzing the causes of cracks, particularly in considering the effects of multiple loads, simulating the crack development process, and assessing crack stability under extreme climatic conditions.

[0068] In some embodiments, such as Figure 1 As shown, the simulation prediction and stability analysis method for spillway dam cracks includes the following steps:

[0069] S1. By pre-setting nonlinear contact elements at the crack locations, a nonlinear finite element model of the downstream facade cracks of the spillway section is established to simulate the cracks in the downstream facade of the spillway section.

[0070] As a possible implementation method, the step includes:

[0071] S1.1 Collect information on the dimensions and materials of the spillway dam, and use nonlinear finite element tools to establish a three-dimensional geometric model of the spillway dam.

[0072] In this sub-step, the geometric dimensions and material properties of the spillway dam, including the elastic modulus and tensile strength of concrete, can be collected from engineering construction data. A three-dimensional geometric model of the spillway dam is then established using existing nonlinear finite element tools, such as... Figure 2 As shown.

[0073] S1.2. Contact elements are used to simulate cracks.

[0074] For describing the contact problem of cracks, in addition to satisfying the basic equations, boundary conditions and initial conditions, the contact conditions on the contact surface must also be satisfied, including: contact displacement conditions, contact force conditions, contact state conditions, etc.

[0075] S1.3 The initial strength of the initial crack is the strength of the concrete itself.

[0076] If the stress exceeds the tensile strength of the concrete, the crack will open automatically, and the tensile stress borne by the concrete unit will be transferred to other concrete units. The propagation after local cracking takes into account the fracture mechanics criteria. After the crack is generated, it will automatically open and close in iteration with the change of stress.

[0077] S2. Apply at least two of the following loads to the model: self-weight, temperature, water pressure, sand pressure, uplift pressure, and valve thrust.

[0078] This application provides a comprehensive analysis of the impact of various loads on crack formation; therefore, the simulated loads include multiple types. Based on the detection results of cracks on the downstream facade of the spillway section, this step involves applying various loads to the finite element model to simulate actual working conditions. These loads include self-weight, temperature changes, water pressure, sand pressure, uplift pressure, and gate thrust.

[0079] 1) Self-weight load: Based on the actual pouring progress of the spillway dam, the self-weight load of the model is simulated to ensure that the load distribution is consistent with the actual construction state.

[0080] 2) Temperature Load: Using temperature monitoring data, temperature loads are obtained through simulation and inversion of the entire construction, water storage, and operation process to reflect the impact of environmental temperature changes on the dam body. For example... Figure 3The image shows a comparison of cracking in summer and winter during the construction of the spillway dam. The left side shows the cracking range in summer, and the right side shows the cracking range in winter. State "0" and "1" are both open states, state "2" is the bonded state, and state "3" is the bonded state after grouting. The influence of temperature on the cracking range can be clearly seen.

[0081] 3) Water pressure load: Simulate the actual upstream and downstream water level changes by applying surface loads to the upstream and downstream surfaces of the spillway to simulate the effect of water pressure.

[0082] 4) Silt load: Apply a surface load to the upstream face of the spillway dam to simulate the pressure of silt on the dam body. Set the silt elevation to 300 meters to reflect the actual silt situation.

[0083] 5) Uplift pressure: According to the design requirements, a vertical upward surface load is applied at the interface of the dam foundation to simulate the effect of uplift pressure on the dam body.

[0084] 6) Gate thrust: When the surface gate and the middle gate are blocking water, the gate thrust is simulated by applying a concentrated force at the gate support to ensure that the impact of the gate on the dam body is accurately simulated.

[0085] By applying the above loads, it can be ensured that the model can accurately reflect the various loads that the spillway dam bears in actual operation, providing accurate load conditions for the subsequent inversion of crack initiation and propagation processes. Figure 4 The diagram shows the crack opening at an elevation of 353m in the spillway dam, revealing a periodic change in crack opening. Combined with... Figure 5 The measured temperature data of the spillway dam shows that the temperature data also exhibits periodic changes. Therefore, it is reasonable to suspect that the factors causing the periodic changes in crack opening may be the various loads mentioned above.

[0086] S3. Conduct simulation calculations for the entire process of construction, water storage, and operation of the spillway dam: Based on the monitoring data of the construction, water storage, and operation of the spillway dam, the nonlinear finite element full-process simulation analysis method is adopted. According to the actual construction progress of the spillway dam, the simulation calculations are performed on the concrete pouring process, hydration heat generation process, hardening process, longitudinal joint grouting process, water cooling, surface insulation measures, air temperature change process, and reservoir water level change process to simulate the temperature field and stress field of the entire process of construction, water storage, and operation of the spillway dam.

[0087] In some feasible implementations, the step includes:

[0088] 1) The simulated concrete pouring process includes:

[0089] The concrete pouring of the spillway dam is carried out in layers, blocks, and sections according to dam segments. The self-weight of each section of concrete poured will act on the already poured concrete structure (including the foundation). Therefore, in this process, the spillway dam is divided into grids, with each grid corresponding to one section of concrete. (Using software such as SAPTIS), each grid cell is sorted according to the pouring sequence, and the corresponding cells are activated step by step to simulate the concrete pouring, forming a step-by-step calculation grid model. The self-weight of the activated cells is used as the load increment. The calculation method for the self-weight load of the simulated pouring cells is as follows:

[0090]

[0091] In the formula, Let N represent the pressure change at the i-th node on element e, N represent the shape function matrix, Δv represent the volume change vector, and Ω represent the domain of element e.

[0092] After concrete is poured, it gradually hardens over time, exhibiting a continuous increase in parameters such as elastic modulus and strength. The heat of hydration of cement is continuously dissipated, causing temperature changes in the dam body along with the boundary temperature. Concrete poured at different times gradually undergoes creep deformation, which affects both the stiffness matrix and the calculated loads. Therefore, in the simulation, it is assumed that the concrete in each unit gradually hardens and undergoes creep deformation after pouring, with the heat of hydration gradually dissipated.

[0093] After each unit of concrete is poured, the time is divided into multiple time intervals, and the temperature field and stress field of the spillway are calculated sequentially for each time step. In each calculation step, the stiffness matrix and load array need to be modified to take into account the above factors.

[0094] 2) The simulated joint grouting process includes:

[0095] In practice, concrete is poured in sections, with expansion joints between the sections and between the poured blocks. Therefore, during the simulation, the expansion joints between the sections and between the poured blocks are grouted sequentially to connect the concrete sections and blocks into a unified whole. For example, the longitudinal joints of a gravity dam must be grouted before the reservoir is filled with water.

[0096] In the simulation, Goodman elements with tensile strength were used to simulate expansion joints, and the discontinuous deformation analysis method (proposed by Shi Genhua, abbreviated as DDA method) was introduced into the finite element method to simulate the opening and closing state of the expansion joints. Generally, expansion joints are in a closed state immediately after concrete is poured. As hydration generates heat, the concrete temperature rises, the concrete expands and deforms, and the joint continuously tightens, meaning the compressive stress on the joint surface continuously increases. After the temperature reaches its peak, with natural heat dissipation or artificial cooling, the normal stress on the joint surface gradually decreases, and the compressive stress changes to tension. When the tensile stress on the joint surface exceeds the tensile strength of the joint, the joint opens.

[0097] The simulation involves layered, segmented, and skip-unit pouring of concrete, as well as layered and phased joint grouting. It tracks the stress changes, opening and closing processes, and expansion joint opening changes of each Goodman unit. When the relevant grouting area (temperature, etc.) meets the grouting requirements and joint grouting is performed, the current opening of each expansion joint is locked, and this current opening is used as the thickness of the Goodman unit. The Goodman unit is filled with grouting material, and the corresponding material parameters are set. Tensile and shear strengths are given according to the following formula:

[0098]

[0099] In the formula, i represents the expansion joint identifier, and δ i For the opening of the expansion joint, These represent the normal and shear stiffness of the expansion joint, respectively; E and μ represent the elastic modulus and Poisson's ratio of the grouting material, respectively. Due to differences in the pouring season, stress conditions, and temperature changes, the opening and closing patterns of concrete in different locations exhibit varying characteristics.

[0100] 3) Simulated water cooling includes:

[0101] The equivalent simulation method is used to simulate the heat removed by water cooling and thus calculate the concrete temperature. Proposed by Zhu Bofang, this method averages the cooling effect of water cooling within the control range of each water pipe, uses a semi-analytical solution of water cooling to determine the heat removed by the water cooling, and then solves for the concrete temperature.

[0102] 4) Simulated surface insulation includes:

[0103] Surface insulation is simulated by changing the surface heat dissipation coefficient, where the surface heat dissipation coefficient β0 when the concrete surface is exposed is calculated by the following formula:

[0104] β0 = 23.9 + 14.50v n ,

[0105] In the formula, v n This refers to wind speed.

[0106] The surface heat dissipation coefficient β when the concrete surface is covered with insulation board s Calculated by the following formula:

[0107]

[0108] In the formula, h i Let λ be the thickness of insulation board i. i Let be the thermal conductivity coefficient of insulation board i.

[0109] The spillway dam described in this application employs a phased water storage strategy. Once the spillway dam reaches a certain height and has initial water-blocking capacity, water storage begins to achieve power generation benefits ahead of schedule. The incremental water load in each phase is borne only by the portion of the dam body that has completed joint grouting, which is significantly different from the stress state of the entire dam body when it is impounded all at once. Therefore, simulation of the high dam is necessary.

[0110] 5) The simulated water storage operation process includes:

[0111] Before impoundment, temperature and stress field models were established by simulating construction, temperature control, and material hydration and hardening processes, with the temperature field acting as a load influencing the stress field. After impoundment began, water pressure was simulated by applying triangular surface loads to the upstream and downstream faces of the spillway dam, and uplift pressure was simulated by applying vertically upward (triangular) surface loads to the dam foundation interface. During impoundment, the temperature boundary conditions on the upstream dam face changed from air temperature boundary conditions to water temperature boundary conditions for the surface during water level rise, while the water level fluctuation zone alternated between air temperature boundary conditions and water temperature boundary conditions.

[0112] In the simulation calculation of the temperature and stress fields of the spillway dam (i.e., simulating the entire construction and operation process), changes in atmospheric hydrological conditions were also considered. The air temperature boundary conditions were set based on measured air temperatures or multi-year monthly average temperatures, and the influence of solar radiation heat was simulated by adding a temperature increment to the set air temperature. This simulation method can more accurately reflect actual operating conditions and provide a scientific basis for the safety assessment of the spillway dam.

[0113] S4. Based on the simulation calculation results of step S3, with the goal of minimizing the difference between the simulation calculation values ​​and the monitoring data of the temperature and deformation of the spillway dam body, the initiation and propagation process of the downstream facade cracks of the spillway dam section is inverted.

[0114] In some embodiments, step S4 includes the inversion of thermal parameters of the spillway concrete and bedrock, as well as the inversion of mechanical parameters of the spillway concrete and bedrock. This step aims to minimize the difference between the simulated values ​​and the monitoring data on the temperature and deformation of the spillway body. It inverts the thermal and mechanical parameters of the spillway concrete and bedrock, analyzes the crack propagation path and rate based on the inverted data, determines the main influencing factors of crack propagation, and thus provides corresponding crack treatment recommendations and implements appropriate crack treatment measures.

[0115] As a feasible implementation method, the inversion of the thermal parameters of the spillway dam concrete and bedrock includes:

[0116] With the goal of minimizing the difference between the simulated values ​​and the monitoring data on the temperature and deformation of the spillway dam body, the thermal conductivity, specific heat, and adiabatic temperature rise parameters of the concrete in different zones of the spillway dam body were obtained through inversion. Specifically, during the simulation calculation, the adiabatic temperature rise during the construction period of the spillway dam body and the temperature recovery after joint grouting were simulated using the following formula:

[0117]

[0118] In the formula, Q(τ) represents the adiabatic temperature rise at the concrete age τ, α1 and α2 are the adiabatic temperature rise parameters of the dam body and joint grouting, respectively; τ is the concrete age; Q1 and Q2 are the final adiabatic temperature rise values ​​of the spillway dam concrete and grouting material, respectively.

[0119] As another feasible approach, the inversion of the mechanical parameters of the spillway dam concrete and bedrock includes:

[0120] Based on the monitoring data of the deformation of the spillway dam, and using the water pressure components at each measuring point obtained from regression, the finite element simulation analysis method is adopted. Considering only the hydrostatic pressure, the deformation of the dam body under different elastic moduli of concrete is simulated and calculated. The calculated deformation is compared with the water pressure deformation components obtained from the multivariate regression of the deformation monitoring data. With the goal of minimizing the error between the simulation calculation value and the water pressure deformation components, the optimal elastic modulus of the concrete and bedrock of the spillway dam body is determined by inversion.

[0121] In the simulation calculation, the following formula is used to simulate the hardening process of the elastic modulus of concrete:

[0122]

[0123] In the formula, E(τ) and E0 are the elastic modulus and final elastic modulus of the dam concrete at an age of τ, respectively, and α and β are the elastic modulus growth rate parameters of the concrete.

[0124] This step, based on step S3 and the design and experimental parameters of the spillway dam body and bedrock materials, uses SAPTIS software to simulate and analyze the temperature and deformation fields (i.e., stress fields) throughout the construction, impoundment, and operation of the spillway section, based on dam temperature and deformation monitoring data. The objective function is to minimize the difference between calculated and monitored values, thereby obtaining the key thermal and mechanical parameters of the dam body and bedrock. The inversion parameters are then used to simulate and calculate the initiation and propagation process of cracks on the downstream facade of the spillway section. By comparing the simulation results with actual monitoring data, the accuracy of the model is verified, and the crack propagation path and rate are analyzed.

[0125] S5. Based on the analysis results of the crack initiation and propagation process in step S4, the crack is repaired accordingly. The state of the crack after treatment is evaluated through simulation and the propagation stability of the crack is analyzed.

[0126] This step aims to predict the state of the crack after treatment and analyze its propagation stability. Based on the analysis results of step S4 above, combined with the crack cause analysis, crack treatment suggestions are proposed, such as epoxy grouting. The state of the crack after treatment is evaluated through simulation prediction analysis, especially its stability under extreme climatic conditions. Special attention is paid to the behavior of cracks under extreme low-temperature conditions to assess the effectiveness of the treatment measures. Therefore, in some embodiments, this step uses simulation to evaluate the state of the crack after treatment and analyze its stability under extreme climatic conditions.

[0127] As a possible implementation method, the step includes:

[0128] 1) Climate data from the historical lowest temperature period were selected as the temperature parameters for simulation. These parameters were used to simulate the crack state during the predetermined normal operation period after crack treatment. The crack propagation stability under different seasonal temperature variations was analyzed by comparing the crack states before and after treatment in winter and summer. The comparison results are as follows: Figure 6 , Figure 7 As shown, where Figure 6 The left side shows the state of the cracks before winter grouting, and the right side shows the state of the cracks after winter grouting. Figure 7 This shows the state of the cracks after grouting in summer.

[0129] 2) Simulate the crack state after removing the insulation board and treating the cracks in winter, such as... Figure 8 As shown, this study analyzes the propagation stability of cracks under extreme low-temperature conditions after crack treatment. After the insulation boards are removed, there is a risk of localized cracking on the downstream facade of the dam during periods of extreme winter temperatures.

[0130] Step S5 can determine the opening and closing state of cracks under different seasonal temperature changes, as well as the stability of cracks under extreme low temperature conditions after treatment, thus providing scientific decision support for the management and maintenance of cracks in spillway dams.

[0131] This application also proposes a device for simulating and predicting cracks in a spillway dam and analyzing its stability, including a processor and a storage medium. The processor runs a computer program stored in the storage medium to execute the method for simulating and predicting cracks in a spillway dam as described in the above embodiments.

[0132] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A method for simulation prediction and stability analysis of cracks in spillway dams, characterized in that, include: S1. By pre-setting nonlinear contact elements at the crack locations, a nonlinear finite element model of the downstream facade cracks of the spillway section is established to simulate the cracks in the downstream facade of the spillway section. S2. Apply at least two of the following loads to the model: self-weight, temperature, water pressure, sand pressure, uplift pressure, and valve thrust. S3. Conduct simulation calculations for the entire process of spillway dam construction, water storage, and operation: Based on monitoring data of the construction, water storage and operation of the spillway dam, a nonlinear finite element full-process simulation analysis method is adopted. According to the actual construction progress of the spillway dam, the simulation calculations of the concrete pouring process, hydration heat generation process, hardening process, longitudinal joint grouting process, water cooling, surface insulation measures, air temperature change process and reservoir water level change process are carried out to simulate the temperature field and stress field of the entire process of the spillway dam construction, water storage and operation. S4. Based on the simulation calculation results of step S3, with the goal of minimizing the difference between the simulation calculation values ​​and the monitoring data of the temperature and deformation of the spillway dam body, the initiation and propagation process of the downstream facade cracks of the spillway dam section is inverted. S5. Based on the analysis results of the crack initiation and propagation process in step S4, the crack is repaired accordingly. The state of the crack after treatment is evaluated through simulation and the propagation stability of the crack is analyzed.

2. The method for simulation prediction and stability analysis of cracks in spillway dams as described in claim 1, characterized in that, Step S1 includes: S1.1 Collect the size and material information of the spillway dam, and use the nonlinear finite element tool to establish a three-dimensional geometric model of the spillway dam; S1.2, Contact elements are used to simulate cracks; S1.3 The initial strength of the initial crack is the strength of the concrete itself.

3. The method for simulation prediction and stability analysis of cracks in spillway dams as described in claim 2, characterized in that, In step S3, the simulated concrete pouring process includes: The spillway dam is divided into grids, and each unit is sorted according to the pouring sequence. The corresponding units are activated step by step to simulate the pouring of concrete. The self-weight of the activated unit is used as the load increment. It is set that the concrete of each unit gradually hardens and undergoes creep deformation after pouring, and the heat of hydration is gradually dissipated. After each unit of concrete is poured, the time is divided into multiple time intervals, and the temperature field and stress field of the spillway dam are calculated in time sequence for each time step. The simulated joint grouting process includes: Grouting is performed on the expansion joints between dam sections and between cast blocks in sequence to connect the concrete of the dam sections and blocks into a whole. Goodman elements with tensile strength were used to simulate expansion joints, and discontinuous deformation analysis was introduced into the finite element method to simulate the opening and closing state of expansion joints. The simulation involves layered, segmented, and skip-unit pouring of concrete, as well as layered and phased joint grouting. It tracks the stress changes, opening and closing processes, and expansion joint opening changes of each Goodman unit. When the relevant grouting area meets the grouting requirements and joint grouting is performed, the current opening of each expansion joint is locked, and this current opening is used as the thickness of the Goodman unit. The Goodman unit is then filled with grouting material, and the corresponding material parameters are set. Tensile and shear strengths are given according to the following formula: In the formula, i represents the expansion joint identifier, and δ i For the opening of the expansion joint, , respectively, represent the normal and shear stiffness of the expansion joint; E and μ represent the elastic modulus and Poisson's ratio of the grouting material, respectively; Simulated water cooling includes: The equivalent simulation method is used to simulate the heat carried away by water cooling in order to calculate the concrete temperature; Simulated surface insulation includes: Surface insulation is simulated by changing the surface heat dissipation coefficient, where the surface heat dissipation coefficient β0 when the concrete surface is exposed is calculated by the following formula: β0＝23.9+14.50v n ， In the formula, v n Wind speed; The surface heat dissipation coefficient β when the concrete surface is covered with insulation board s Calculated by the following formula: In the formula, h i Let λ be the thickness of insulation board i. i Let i be the thermal conductivity coefficient of the insulation board. The simulated water storage operation process includes: Before impounding water, temperature and stress field models were established by simulating construction, temperature control, and material hydration and hardening processes. After impounding water began, water pressure was simulated by applying triangular surface loads to the upstream and downstream faces of the spillway dam, and uplift pressure was simulated by applying vertical surface loads to the dam foundation interface. During the impounding process, the temperature boundary conditions of the upstream dam face changed from air temperature boundary conditions to water temperature boundary conditions for the surface of the rising water level, while the water level fluctuation zone alternated between air temperature boundary conditions and water temperature boundary conditions. In the simulation calculation of the temperature field and stress field of the spillway dam, the temperature boundary conditions are set according to the measured temperature or the multi-year monthly average temperature, and the influence of solar radiation heat is simulated by adding a temperature increment to the set temperature.

4. The method for simulation prediction and stability analysis of cracks in spillway dams as described in claim 1, characterized in that, In step S4, the initiation and propagation process of cracks on the downstream facade of the spillway section is inverted, including the inversion of thermal parameters of the spillway concrete and bedrock, as well as the inversion of mechanical parameters of the spillway concrete and bedrock.

5. The method for simulation prediction and stability analysis of cracks in spillway dams as described in claim 4, characterized in that, The inversion of thermal parameters of the spillway dam concrete and bedrock includes: With the goal of minimizing the difference between the simulated values ​​and the monitoring data on the temperature and deformation of the spillway dam body, the thermal conductivity, specific heat, and adiabatic temperature rise parameters of the concrete in different zones of the spillway dam body were obtained through inversion. Specifically, during the simulation calculation, the adiabatic temperature rise during the construction period of the spillway dam body and the temperature recovery after joint grouting were simulated using the following formula: In the formula, Q(τ) represents the adiabatic temperature rise at the concrete age τ, α1 and α2 are the adiabatic temperature rise parameters of the dam body and joint grouting, respectively; τ is the concrete age; Q1 and Q2 are the final adiabatic temperature rise values ​​of the spillway dam concrete and grouting material, respectively.

6. The method for simulation prediction and stability analysis of cracks in spillway dams as described in claim 4, characterized in that, The inversion of mechanical parameters of the spillway dam concrete and bedrock includes: Based on the monitoring data of the deformation of the spillway dam, and using the water pressure components at each measuring point obtained from regression, the finite element simulation analysis method is adopted. Considering only the hydrostatic pressure, the deformation of the dam body under different elastic moduli of concrete is simulated and calculated. The calculated deformation is compared with the water pressure deformation components obtained from the multivariate regression of the deformation monitoring data. With the goal of minimizing the error between the simulation calculation value and the water pressure deformation components, the optimal elastic modulus of the concrete and bedrock of the spillway dam body is determined by inversion. In the simulation calculation, the following formula is used to simulate the hardening process of the elastic modulus of concrete: In the formula, E(τ) and E0 are the elastic modulus and final elastic modulus of the dam concrete at an age of τ, respectively, and α and β are the elastic modulus growth rate parameters of the concrete.

7. The method for simulation prediction and stability analysis of cracks in spillway dams as described in claim 1, characterized in that, In step S5, the state of the crack after treatment is evaluated through simulation and the stability under extreme climatic conditions is analyzed.

8. The method for simulation prediction and stability analysis of cracks in spillway dams as described in claim 7, characterized in that, The process of evaluating the state of cracks after treatment through simulation and analyzing their stability under extreme climatic conditions includes: Climate data from historically lowest temperature periods were selected as the temperature parameters for simulation. These parameters were used to simulate the crack state during the predetermined normal operation period after crack treatment. By comparing the crack states before and after treatment in winter and summer, the propagation stability of the cracks under different seasonal temperature variations was analyzed. The simulation was conducted to examine the crack state after the insulation board was removed and crack treatment was performed in winter, in order to analyze the crack propagation stability under extreme low temperature conditions.

9. A device for simulating, predicting, and analyzing the stability of cracks in a spillway dam, comprising a processor and a storage medium, characterized in that, The processor runs the computer program stored in the storage medium to perform the flood discharge dam crack simulation prediction and stability analysis method as described in any one of claims 1-8.

Images