Sluice structure safety analysis method under cyclic load

Abstract

The invention discloses a method for analyzing the safety of a water gate structure under cyclic loading. The method comprises the following steps: S1, acquiring basic data of the water gate structure; s2, constructing a three-dimensional finite element model of the water gate structure, and simulating the mechanical response of the water gate under the actual working condition; s3, determining characteristic parameters of the cyclic load; s4, applying a cyclic load to the three-dimensional finite element model, and obtaining a load value of the water gate structure under the action of the cyclic load; s5, calculating the damage variable of the water gate structure, and determining the damage degree of the structure; s6, constructing a reliability model, and performing reliability analysis on the water gate structure to obtain a reliability index of the water gate structure under the cyclic load; and S7, establishing a water gate structure safety evaluation system, and outputting a safety evaluation report. The method achieves the evaluation of the mechanical response, damage degree and reliability of the water gate structure under the cyclic load, provides a scientific basis for the maintenance and management of the water gate, and guarantees the safe and stable operation of the water gate.

Description

Technical Field

[0001] The invention relates to the technical field of sluice structures, and in particular to a safety analysis method for sluice structures under cyclic loads. Background Art

[0002] As a key facility in water conservancy projects, sluice gates play a vital role in flood control, irrigation, and navigation. In actual operation, sluice gates are subject to various complex loads, among which cyclic loads are more common and have a significant impact. For example, the periodic rise and fall of water levels, the pulsation of water flow, earthquake loads, and repeated impacts of wind and waves will cause the sluice structure to bear cyclic loads. Under the action of cyclic loads for a long time, the stress and strain state inside the sluice structure is constantly changing, which is easy to cause structural damage, fatigue damage and other problems, seriously threatening the safe operation of the sluice gate. Once the sluice gate has safety problems, it will lead to a series of serious consequences such as flooding and imbalance in water resources allocation, causing huge losses to people's lives and property safety and social and economic development. Therefore, accurately analyzing the safety of the sluice structure under cyclic loads is of great practical significance for ensuring the reliable operation of the sluice gate and extending its service life.

[0003] Traditionally, when analyzing the safety of sluice structures, methods based on empirical formulas and simplified calculation models are often used. These methods usually regard the sluice structure as a simple mechanical system, ignoring the complexity of the structure and the diversity of actual working conditions. For example, when calculating the bearing capacity of the sluice, only the static load effect is considered, and the stress and deformation of the structure are estimated by simple material mechanics formulas. The advantage of this method is that the calculation process is relatively simple, easy to understand and operate, and has certain application value in the early design and analysis of water conservancy projects. However, its disadvantages are also very obvious. Due to the neglect of important factors such as cyclic loads and nonlinear characteristics of the structure, there is a large deviation between the calculation results and the actual situation, and it is impossible to accurately evaluate the safety of the sluice under complex working conditions. This leads to misjudgment of the safety performance of the sluice structure, either overestimating the structural safety, burying safety hazards in the project; or underestimating the structural safety, resulting in unnecessary engineering reinforcement and investment waste.

[0004] With the development of computer technology and numerical analysis methods, existing technologies have made certain progress in the safety analysis of sluice structures. At present, finite element analysis methods are widely used in the mechanical analysis of sluice structures. By establishing a finite element model of the sluice structure, the geometric shape, material properties and various load conditions of the structure can be considered to simulate the stress and strain distribution of the sluice structure more accurately. When considering cyclic loads, some existing technologies can perform simple time-history analysis to obtain the response of the structure under cyclic loads.

[0005] However, the existing technology still has some shortcomings. On the one hand, when establishing the finite element model, there is a lack of unified standards for unit division and parameter selection, and the modeling methods of different researchers vary greatly, which affects the comparability and reliability of the analysis results. On the other hand, when evaluating the safety of sluice structures, the existing technology focuses on the mechanical response analysis of the structure, and the comprehensive consideration of the structural damage evolution and reliability assessment is not comprehensive enough, making it difficult to provide an accurate and comprehensive safety evaluation of the sluice structure.

[0006] Therefore, in order to solve the above problems, this application proposes a method for analyzing the safety of sluice structures under cyclic loads, which solves the above-mentioned technical problems. Summary of the invention

[0007] Based on the above content, this application proposes a safety analysis method for a sluice structure under cyclic load, comprising the following steps:

[0008] S1. Obtain basic data of the sluice structure, wherein the basic data includes structural design parameters and material characteristic parameters of the sluice;

[0009] S2. Based on the basic data, construct a three-dimensional finite element model of the sluice structure to simulate the mechanical response of the sluice under actual working conditions;

[0010] S3. Determine the characteristic parameters of cyclic loads, including load amplitude, frequency, action duration and number of cycles, based on the hydrological data and operation records of the area where the sluice is located;

[0011] S4, applying the cyclic load to the three-dimensional finite element model, performing time history analysis, and obtaining the load value of the sluice structure under the cyclic load;

[0012] S5. Calculate the damage variable of the sluice structure by using the structural damage function through the load value to determine the damage degree of the structure;

[0013] S6. Construct a reliability model, conduct reliability analysis on the sluice structure according to the uncertainty of the cyclic load of the sluice structure, and obtain the reliability index of the structure under the cyclic load;

[0014] S7. Based on the damage degree and reliability index, a safety evaluation system for the sluice structure is established. Based on the system, the safety of the sluice structure is graded and evaluated, and a safety evaluation report is output.

[0015] Preferably, the construction of the three-dimensional finite element model of the sluice structure in S2 specifically includes:

[0016] The sluice structure is divided into multiple units, including solid units and plate-shell units. A three-dimensional finite element model of the sluice structure is constructed by obtaining the displacement vectors and stress tensors of the solid units and the plate-shell units. The solid units are divided into micro-units by eight-node hexahedral isoparametric units, and the displacement vectors of the micro-units are obtained. The plate-shell units are divided into micro-units by four-node thin plate units, and the displacement vectors of the micro-units are obtained. The stress tensors of the solid units and the plate-shell units are obtained through the elastic-plastic structural model.

[0017] Preferably, the solid unit is divided into micro-units by eight-node hexahedral isoparametric units, and the displacement vector is obtained, which specifically includes:

[0018] Get the displacement vector of any point of the micro-unit , the formula is: ,in is the entity shape function, for Point displacement vector; local coordinates of the microelement Computing Solid Shape Functions , the formula is: ,in for The local coordinates of the point micro-unit body; the displacement vectors of the micro-unit body in the solid unit are combined to obtain the displacement vector of the solid unit.

[0019] Preferably, the plate-shell element is divided into micro-element bodies by a four-node thin plate element, and the displacement vector is obtained, which specifically includes:

[0020] Get the displacement vector of any point of the micro-unit , the formula is: ,in for Point displacement vector, is the plate and shell shape function, for Dot Wrap Axis and The rotation angle of the axis; through the local coordinates of the microcell Calculate the shape function of the plate and shell, the formula is: ,in for The local coordinates of the point micro-element body; the displacement vectors of the micro-element body in the plate and shell unit are combined to obtain the displacement vector of the plate and shell unit.

[0021] Preferably, the three-dimensional finite element model is constructed by obtaining the stress tensor and displacement vector of the solid unit and the plate and shell unit, and the stress tensor is obtained through the elastic-plastic structure model, specifically:

[0022] Obtaining damage variables of solid elements and plate-shell elements of sluice structures and the strain tensor , construct the elastic-plastic structural model, the formula is: ,in is the stress tensor, is the initial damage variable, and the stress tensor of the solid element and the plate and shell element is obtained. , the stress tensor through the solid element and the plate and shell element The displacement vectors of solid elements and plate and shell elements are combined to construct a three-dimensional finite element model.

[0023] Preferably, in S4, a cyclic load is applied to the three-dimensional finite element model, and a time history analysis is performed to obtain the load value of the sluice structure under the cyclic load, specifically:

[0024] The characteristic parameters of the cyclic load are discretized according to the set time step. , divide the duration of cyclic load into multiple time nodes , the formula is: ,in is the time step value; at each time point, according to the load amplitude ,frequency Calculate the load value at the current moment using the number of cycles , the formula is: ,in The load correction function adjusted for the number of cycles is given by: ,in is the total number of time steps, is the time step corresponding to the number of cycles; the load value of the sluice structure under the cyclic load is obtained through the above formula to evaluate the damage degree of the sluice structure.

[0025] Preferably, after obtaining the load value of the sluice structure under the cyclic load in S5, the damage variable is calculated using the structural damage function, and the formula is: ,in For the The load value for each time step, is the time cumulative weight coefficient, is the bearing capacity of the sluice structure, is the nonlinear coefficient of the sluice structure, is the total number of time steps; the load values ​​corresponding to the different regions of the sluice structure are calculated through the structural damage function to obtain the damage variables of the different regions of the sluice structure .

[0026] Preferably, the damage variables of the sluice structure are divided into different regions. Determine the extent of structural damage, specifically:

[0027] Constructing comprehensive evaluation indicators , the comprehensive evaluation index Including damage variables and the damage variable change rate , the formula is: ,in , are the corresponding weight coefficients respectively; set different damage levels The threshold range is divided into four levels: slight damage, moderate damage, severe damage and serious damage, and comprehensive evaluation indicators are obtained through real-time monitoring. ,in accordance with Determine the threshold range and obtain the current damage degree.

[0028] Preferably, the reliability model is constructed in S6 to perform reliability analysis on the sluice structure to obtain the failure probability and reliability index of the structure under cyclic load, which specifically includes:

[0029] The uncertainty of cyclic loading is expressed as a random variable vector Said, the formula is: ,in is the load amplitude, is the load frequency, and the random variable vector Input into the 3D finite element model to construct the limit state function , the formula is: ,in is the structural resistance of the sluice gate, is the cyclic load effect function; the reliability index is calculated by the first-order second moment method , the formula is: ,in and They are The mean and variance of .

[0030] Preferably, the comprehensive damage degree and reliability index in S7 establish a sluice structure safety evaluation system and conduct graded evaluation, specifically including:

[0031] Constructing a comprehensive evaluation function , the formula is: ,in is the damage variable of the sluice structure, As a reliable indicator, It is the maximum reliable indicator under ideal conditions; and are the weight coefficients of damage degree and reliability index respectively. The hierarchical analysis method is used to divide the The different safety level intervals corresponding to the values ​​include excellent, good, qualified, warning and dangerous levels. and Substituting into the comprehensive evaluation function, we get Value, according to The range of values ​​determines the safety level of the sluice structure and completes the graded assessment.

[0032] Compared with the prior art, the technical solution of this application has the following technical effects:

[0033] The present invention obtains basic data of the sluice structure, constructs a three-dimensional finite element model to simulate the mechanical response under actual working conditions, and then applies cyclic loads for time-history analysis. This technical solution solves the technical problem that traditional methods are difficult to accurately simulate the mechanical state of the sluice under complex cyclic loads. The load value of the sluice structure under cyclic loads can be accurately obtained, which provides reliable data support for the subsequent evaluation of the degree of structural damage and safety. Compared with traditional methods, the accuracy of the mechanical response analysis of the sluice structure is greatly improved.

[0034] The present invention calculates the damage variables of the sluice structure by using the structural damage function, and constructs a comprehensive evaluation index combining the damage variables and the damage variable change rate to determine the technical solution of the structural damage degree, thereby solving the technical problem that it is difficult to accurately evaluate the damage degree of the sluice structure under cyclic loads. The damage degree of the sluice structure can be divided into four levels: slight damage, moderate damage, severe damage and serious damage, thereby realizing a quantitative evaluation of the structural damage status, so that management personnel can intuitively understand the damage condition of the sluice and take corresponding maintenance or reinforcement measures in a timely manner.

[0035] The present invention solves the technical problem that it is difficult to consider the uncertainty of cyclic loads in the safety analysis of sluice structures by expressing the uncertainty of cyclic loads as a random variable vector, constructing a limit state function and using a first-order second moment method to calculate the reliability index. The present invention can calculate the failure probability and reliability index of the structure under cyclic loads, evaluate the safety of the sluice structure from the perspective of reliability, provide a more scientific basis for engineering decision-making, and avoid safety hazards or over-design caused by ignoring load uncertainty.

[0036] The present invention solves the technical problem that the existing technology is difficult to comprehensively and accurately evaluate the safety of the sluice structure by constructing a comprehensive evaluation function, combining damage variables and reliability indicators, and using the hierarchical analysis method to divide the safety level intervals. The safety level of the sluice structure is divided into five levels: excellent, good, qualified, warning and dangerous. A comprehensive graded evaluation is conducted on the safety of the sluice, and a detailed safety assessment report is output, which is convenient for engineering personnel to fully understand the safety status of the sluice, formulate management and maintenance strategies in a targeted manner, and ensure the safe and stable operation of the sluice.

[0037] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application so that it can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings as follows.

[0038] Based on the detailed description of the specific embodiments of the present application in combination with the accompanying drawings below, those skilled in the art will become more aware of the above and other objects, advantages and features of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings without creative work. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0040] Figure 1 It is a flow chart of a method for analyzing the safety of a sluice structure under cyclic loads according to the present invention;

[0041] Figure 2 A solid unit division diagram of a method for analyzing the safety of a sluice structure under cyclic loads according to the present invention;

[0042] Figure 3 A plate-shell unit division diagram of a sluice structure safety analysis method under cyclic loads according to the present invention;

[0043] Figure 4 This is an evaluation output diagram of a sluice structure safety analysis method under cyclic loads according to the present invention. DETAILED DESCRIPTION

[0044] To make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all of the embodiments. In the following description, specific details such as specific configuration and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures is omitted in the embodiment.

[0045] It should be understood that the references to "one embodiment" or "this embodiment" throughout the specification mean that the specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present application. Therefore, the references to "one embodiment" or "this embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0046] In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0047] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" in this article describes another type of association object relationship, indicating that there can be two relationships. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0048] The term "at least one" in this article is merely a description of the association relationship of associated objects, indicating that there may be three relationships. For example, at least one of A and B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0049] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusions.

[0050] Example 1

[0051] This embodiment mainly describes a method for analyzing the safety of a sluice structure under cyclic loads. Figure 1 As shown, the following steps are included:

[0052] S1. Obtain basic data of the sluice structure, including structural design parameters and material characteristic parameters of the sluice;

[0053] S2. Based on the basic data, a three-dimensional finite element model of the sluice structure is constructed to simulate the mechanical response of the sluice under actual working conditions;

[0054] S3. Determine the characteristic parameters of cyclic loads, including load amplitude, frequency, action duration and number of cycles, based on the hydrological data and operation records of the area where the sluice is located;

[0055] S4, applying the cyclic load to the three-dimensional finite element model, performing time history analysis, and obtaining the load value of the sluice structure under the cyclic load;

[0056] S5. Calculate the damage variable of the sluice structure by using the structural damage function through the load value to determine the damage degree of the structure;

[0057] S6. Construct a reliability model, conduct reliability analysis on the sluice structure according to the uncertainty of the cyclic load of the sluice structure, and obtain the reliability index of the structure under the cyclic load;

[0058] S7. Based on the comprehensive damage degree and reliability indicators, a safety evaluation system for the sluice structure is established. Based on the system, the safety of the sluice structure is graded and evaluated, and a safety evaluation report is output.

[0059] Furthermore, the three-dimensional finite element model of the sluice structure in S2 was constructed, including:

[0060] The sluice structure is divided into multiple units, including solid units and plate-shell units. The three-dimensional finite element model of the sluice structure is constructed by obtaining the displacement vectors and stress tensors of the solid units and plate-shell units. The solid units are divided into micro-units through eight-node hexahedral isoparametric units to obtain the displacement vectors of the micro-units. The plate-shell units are divided into micro-units through four-node thin plate units to obtain the displacement vectors of the micro-units. The stress tensors of the solid units and plate-shell units are obtained through the elastic-plastic structure model.

[0061] Furthermore, the solid element is divided into micro-element bodies through eight-node hexahedral isoparametric elements to obtain the displacement vector, which specifically includes:

[0062] Get the displacement vector of any point of the micro-unit , the formula is: ,in is the entity shape function, for Point displacement vector; local coordinates of the microelement Computing Solid Shape Functions , the formula is: ,in for The local coordinates of the point micro-unit body; the displacement vectors of the micro-unit body in the solid unit are combined to obtain the displacement vector of the solid unit.

[0063] Furthermore, the plate and shell element is divided into micro-element bodies through the four-node thin plate element to obtain the displacement vector, which specifically includes:

[0064] Get the displacement vector of any point of the micro-unit , the formula is: ,in for Point displacement vector, is the plate and shell shape function, for Dot Wrap Axis and The rotation angle of the axis; through the local coordinates of the microcell Calculate the shape function of the plate and shell, the formula is: ,in for The local coordinates of the point micro-element body; the displacement vectors of the micro-element body in the plate and shell unit are combined to obtain the displacement vector of the plate and shell unit.

[0065] Furthermore, the three-dimensional finite element model is constructed by obtaining the stress tensors and displacement vectors of the solid unit and the plate and shell unit. The stress tensors are obtained through the elastic-plastic structural model, specifically:

[0066] Obtaining damage variables of solid elements and plate-shell elements of sluice structures and the strain tensor , construct the elastic-plastic structural model, the formula is: ,in is the stress tensor, is the initial damage variable, and the stress tensor of the solid element and the plate and shell element is obtained. , the stress tensor through the solid element and the plate and shell element The displacement vectors of solid elements and plate and shell elements are combined to construct a three-dimensional finite element model.

[0067] Furthermore, in S4, the cyclic load is applied to the three-dimensional finite element model, and a time history analysis is performed to obtain the load value of the sluice structure under the cyclic load, specifically:

[0068] The characteristic parameters of the cyclic load are discretized according to the set time step. , divide the duration of cyclic load into multiple time nodes , the formula is: ,in is the time step value; at each time point, according to the load amplitude ,frequency Calculate the load value at the current moment using the number of cycles , the formula is: ,in The load correction function adjusted for the number of cycles is given by: ,in is the total number of time steps, is the time step corresponding to the number of cycles; the load value of the sluice structure under the cyclic load is obtained through the above formula to evaluate the damage degree of the sluice structure.

[0069] Furthermore, after obtaining the load value of the sluice structure under the cyclic load in S5, the damage variable is calculated using the structural damage function, and the formula is: ,in For the The load value for each time step, is the time cumulative weight coefficient, is the bearing capacity of the sluice structure, is the nonlinear coefficient of the sluice structure, is the total number of time steps; the load values ​​corresponding to the different regions of the sluice structure are calculated through the structural damage function to obtain the damage variables of the different regions of the sluice structure .

[0070] Furthermore, according to the damage variables of the sluice structure in different regions Determine the extent of structural damage, specifically:

[0071] Constructing comprehensive evaluation indicators , comprehensive evaluation indicators Including damage variables and the damage variable change rate , the formula is: ,in , are the corresponding weight coefficients respectively; set different damage levels The threshold range is divided into four levels: slight damage, moderate damage, severe damage and serious damage, and comprehensive evaluation indicators are obtained through real-time monitoring. ,in accordance with Determine the threshold range and obtain the current damage degree.

[0072] Furthermore, a reliability model is constructed in S6 to conduct reliability analysis on the sluice structure and obtain the failure probability and reliability index of the structure under cyclic loads, including:

[0073] The uncertainty of cyclic loading is expressed as a random variable vector Said, the formula is: ,in is the load amplitude, is the load frequency, and the random variable vector Input into the 3D finite element model to construct the limit state function , the formula is: ,in is the structural resistance of the sluice gate, is the cyclic load effect function; the reliability index is calculated by the first-order second moment method , the formula is: ,in and They are The mean and variance of .

[0074] Furthermore, the damage degree and reliability indexes are integrated in S7 to establish a safety evaluation system for sluice structures and conduct graded evaluation, including:

[0075] Constructing a comprehensive evaluation function , the formula is: ,in is the damage variable of the sluice structure, As a reliable indicator, It is the maximum reliable indicator under ideal conditions; and are the weight coefficients of damage degree and reliability index respectively. The hierarchical analysis method is used to divide the The different safety level intervals corresponding to the values ​​include excellent, good, qualified, warning and dangerous levels. and Substituting into the comprehensive evaluation function, we get Value, according to The range of values ​​determines the safety level of the sluice structure and completes the graded assessment.

[0076] This embodiment describes in detail how to construct a three-dimensional finite element model by acquiring basic data of the sluice structure, simulate the mechanical response under actual working conditions, determine the characteristic parameters of the cyclic load and apply them to the model for time-history analysis, calculate the damage variable using the structural damage function, build a reliability model to analyze the reliability, and then establish a safety evaluation system, which solves the problem of inaccurate safety assessment of the sluice under cyclic loads, can accurately analyze the mechanical response, damage degree and reliability of the sluice structure, realize safety graded assessment, and output an assessment report, providing a scientific basis for sluice maintenance and management, and ensuring the safe and stable operation of the sluice.

[0077] Based on Example 1, this example describes dividing the sluice structure into multiple units, which include solid units and plate-shell units. The solid units are divided into micro-units by eight-node hexahedral isoparametric units, and the plate-shell units are divided into micro-units by four-node thin plate units. Specifically:

[0078] like Figure 2As shown in the figure, the solid unit is divided into micro-units by eight-node hexahedron isoparametric units. Eight-node hexahedron isoparametric units are selected to divide the solid unit. From the perspective of geometric adaptability, the shape of the eight-node hexahedron is regular and flexible, which can better fit the various complex solid shapes in the sluice structure. The foundation and pier of the sluice often have irregular shapes and complex internal structures. The eight-node hexahedron isoparametric units can accurately discretize these areas through reasonable arrangement and combination, thereby minimizing the error caused by the mismatch between the unit shape and the actual structure.

[0079] In terms of mechanical performance simulation, the eight-node hexahedron isoparametric unit has high accuracy. It uses eight nodes to describe the mechanical properties of the unit and reflects the stress and strain distribution inside the unit. Compared with some simple unit division methods, the eight-node hexahedron isoparametric unit can better capture the mechanical response under complex stress states. When the sluice gate is subjected to cyclic loads, complex stress changes will occur inside the structure. The eight-node hexahedron isoparametric unit can simulate these changes more carefully, providing strong support for accurately evaluating the safety of the sluice gate structure. In addition, the eight-node hexahedron isoparametric unit has good stability during the calculation process. Its mathematical model and calculation method are relatively mature, which can ensure the calculation efficiency and result reliability in large-scale finite element analysis.

[0080] like Figure 3 As shown in the figure, the plate-shell unit is divided into micro-units by four-node thin plate units. The use of four-node thin plate units to divide the plate-shell unit is based on the mechanical characteristics and analysis requirements of the plate-shell structure; the plate-shell structure in the sluice is mainly subjected to bending and shear loads, and the four-node thin plate unit can adapt well to this force characteristic. From a geometric point of view, the shape of the four-node thin plate unit is simple and easy to arrange on the plate-shell structure. It can flexibly simulate plates and shells of various shapes. Whether it is a flat plate or a shell with a certain curvature, it can be accurately simulated by reasonably dividing the four-node thin plate unit.

[0081] In terms of mechanical calculations, the displacement vector calculation formula of the four-node thin plate element comprehensively considers the displacement and rotation of the node, which is crucial for accurately describing the deformation of the plate and shell structure. When the plate and shell are subjected to force, in addition to the translational displacement, the rotational deformation around the axis has a significant effect on their mechanical properties. By introducing the degree of freedom of rotation, the four-node thin plate element can more realistically reflect the deformation of the plate and shell structure under load. For example, when the top plate of the sluice chamber is subjected to water flow pressure, the top plate will bend and deform. The four-node thin plate element can accurately simulate this bending deformation and the resulting stress distribution. Moreover, the computational complexity of the four-node thin plate element is relatively low. On the premise of ensuring the calculation accuracy, it can improve the efficiency of finite element analysis, meet the needs of fast and accurate analysis of the sluice structure, and save time and computing resources for the safety assessment of the sluice structure.

[0082] This embodiment describes in detail how to divide the sluice structure into solid and plate-shell units, and subdivide them with eight-node hexahedral isoparametric units and four-node thin plate units, respectively, to accurately simulate its mechanical response, capture the stress and strain of the sluice under cyclic loads, accurately calculate damage variables and reliability indicators, and then establish a comprehensive safety evaluation system. Ultimately, a scientific assessment of the safety of the sluice structure is achieved, providing strong support for sluice maintenance and reinforcement decisions, ensuring the safe and stable operation of the sluice, reducing potential risks, and extending the service life of the sluice.

[0083] Based on Example 1, this example describes in detail how to establish a sluice structure safety evaluation system based on the damage degree and reliability index and perform a graded evaluation, such as Figure 4 As shown, specifically:

[0084] The sluice structure assessment system includes the setting of damage level and safety level range; the damage level reflects the actual damage degree of the structure under cyclic loads and the current physical state of the structure by analyzing the damage variables and their change rates; the safety level range takes into account the structural damage and reliability indicators, measures the safety and reliability of the sluice under various uncertain factors, and is a comprehensive evaluation of the overall safety of the sluice.

[0085] Establish the corresponding relationship between the damage level and the safety level range. Under the light damage level, if the reliability index is high, the calculated The value is in the excellent or good range, which means that although the sluice gate has slight damage, the overall safety is still high and only routine inspection and maintenance are required; when it is moderately damaged, The value may fall into the acceptable range, indicating that although the structure has some damage, it is still within the acceptable range. However, it is necessary to increase the monitoring frequency and arrange repair work in a timely manner. The value is in the warning range, at this time the structural damage is serious, the safety risk increases significantly, and a detailed reinforcement plan must be formulated as soon as possible. The value must be in a dangerous range, the sluice gate can no longer operate normally, and emergency rescue measures are urgently needed, or even reconstruction should be considered.

[0086] In actual operation, these two assessment results can be flexibly used according to different assessment purposes and scenarios. For daily inspections, priority is given to the damage level, which can quickly determine whether the sluice gate has abnormal damage. Once the degree of damage is found to have increased, a comprehensive analysis is immediately conducted in combination with the safety level interval. If the safety level also decreases, it means that the problem is more serious and more resources need to be invested to deal with it. When upgrading the safety assessment or long-term planning of the sluice gate, the safety level interval is taken as the core, and the damage level is referred to to understand the historical damage development of the structure, so as to provide a basis for subsequent reinforcement and transformation and life prediction. In this way, the organic combination of damage level and safety level interval can form a set of well-organized, comprehensive and effective assessment system, which provides a solid guarantee for the safe and stable operation of the sluice gate and ensures that the functions of the water conservancy project can be continuously exerted.

[0087] This embodiment describes in detail how to combine the sluice structure damage level with the safety level interval to avoid repeated evaluations and provide key information for sluice evaluation from multiple dimensions. By establishing a corresponding relationship, the evaluation results can be flexibly used in daily inspections and long-term planning to quickly determine the condition of the sluice, provide a scientific basis for maintenance and reinforcement decisions, ensure the safe and stable operation of the sluice, and ensure that the water conservancy project continues to function.

[0088] The above are only preferred embodiments of the present invention, which do not limit the scope of protection of the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any changes, modifications, replacements, integrations and parameter changes to these embodiments within the spirit and principles of the present invention through conventional substitutions or without departing from the principles and spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A method for analyzing the safety of a sluice structure under cyclic loads, characterized in that: include: S1. Obtain basic data of the sluice structure, wherein the basic data includes structural design parameters and material characteristic parameters of the sluice; S2. Based on the basic data, construct a three-dimensional finite element model of the sluice structure to simulate the mechanical response of the sluice under actual working conditions; S3. Determine the characteristic parameters of cyclic loads, including load amplitude, frequency, action duration and number of cycles, based on the hydrological data and operation records of the area where the sluice is located; S4, applying the cyclic load to the three-dimensional finite element model, performing time history analysis, and obtaining the load value of the sluice structure under the cyclic load; S5. Calculate the damage variable of the sluice structure by using the structural damage function through the load value to determine the damage degree of the structure; S6. Construct a reliability model, conduct reliability analysis on the sluice structure according to the uncertainty of the cyclic load of the sluice structure, and obtain the reliability index of the structure under the cyclic load; S7. Based on the damage degree and reliability index, a safety evaluation system for the sluice structure is established. Based on the system, the safety of the sluice structure is graded and evaluated, and a safety evaluation report is output.

2. A method for analyzing the safety of a sluice structure under cyclic load according to claim 1, characterized in that: The construction of the three-dimensional finite element model of the sluice structure in S2 specifically includes: The sluice structure is divided into multiple units, including solid units and plate-shell units. A three-dimensional finite element model of the sluice structure is constructed by obtaining the displacement vectors and stress tensors of the solid units and the plate-shell units. The solid units are divided into micro-units by eight-node hexahedral isoparametric units, and the displacement vectors of the micro-units are obtained. The plate-shell units are divided into micro-units by four-node thin plate units, and the displacement vectors of the micro-units are obtained. The stress tensors of the solid units and the plate-shell units are obtained through the elastic-plastic structural model.

3. A method for analyzing the safety of a sluice structure under cyclic load according to claim 2, characterized in that: The solid unit is divided into micro-units by eight-node hexahedral isoparametric units to obtain the displacement vector, which specifically includes: Get the displacement vector of any point of the micro-unit , the formula is: ,in is the entity shape function, for Point displacement vector; local coordinates of the microelement Computing Solid Shape Functions , the formula is: ,in for The local coordinates of the point micro-unit body; the displacement vectors of the micro-unit body in the solid unit are combined to obtain the displacement vector of the solid unit.

4. A method for analyzing the safety of a sluice structure under cyclic load according to claim 2, characterized in that: The plate and shell element is divided into micro-element bodies by a four-node thin plate element to obtain a displacement vector, specifically including: Get the displacement vector of any point of the micro-unit , the formula is: ,in for Point displacement vector, is the plate and shell shape function, for Dot Wrap Axis and The rotation angle of the axis; through the local coordinates of the microcell Calculate the shape function of the plate and shell, the formula is: ,in for The local coordinates of the point micro-element body; the displacement vectors of the micro-element body in the plate and shell unit are combined to obtain the displacement vector of the plate and shell unit.

5. A method for analyzing the safety of a sluice structure under cyclic load according to claim 2, characterized in that: The three-dimensional finite element model is constructed by obtaining the stress tensor and displacement vector of the solid unit and the plate and shell unit. The stress tensor is obtained through the elastic-plastic structure model, specifically: Obtaining damage variables of solid elements and plate-shell elements of sluice structures and the strain tensor , construct the elastic-plastic structural model, the formula is: ,in is the stress tensor, is the initial damage variable, and the stress tensor of the solid element and the plate and shell element is obtained. , the stress tensor through the solid element and the plate and shell element The displacement vectors of solid elements and plate and shell elements are combined to construct a three-dimensional finite element model.

6. A method for analyzing the safety of a sluice structure under cyclic load according to claim 1, characterized in that: In S4, the cyclic load is applied to the three-dimensional finite element model, and a time history analysis is performed to obtain the load value of the sluice structure under the cyclic load, specifically: The characteristic parameters of the cyclic load are discretized according to the set time step. , divide the duration of cyclic load into multiple time nodes , the formula is: ,in is the time step value; At each time point, according to the load amplitude ,frequency Calculate the load value at the current moment using the number of cycles , the formula is: ,in The load correction function adjusted for the number of cycles is given by: ,in is the total number of time steps, is the time step corresponding to the number of cycles; the load value of the sluice structure under the cyclic load is obtained through the above formula to evaluate the damage degree of the sluice structure.

7. A method for analyzing the safety of a sluice structure under cyclic load according to claim 1 or 6, characterized in that: After obtaining the load value of the sluice structure under the cyclic load in S5, the damage variable is calculated using the structural damage function, and the formula is: ,in For the The load value for each time step, is the time cumulative weight coefficient, is the bearing capacity of the sluice structure, is the nonlinear coefficient of the sluice structure, is the total number of time steps; the load values ​​corresponding to the different regions of the sluice structure are calculated through the structural damage function to obtain the damage variables of the different regions of the sluice structure .

8. A method for analyzing the safety of a sluice structure under cyclic load according to claim 7, characterized in that: Damage variables according to different regions of sluice structure Determine the extent of structural damage, specifically: Constructing comprehensive evaluation indicators , the comprehensive evaluation index Including damage variables and the damage variable change rate , the formula is: ,in , are the corresponding weight coefficients respectively; set different damage levels The threshold range is divided into four levels: slight damage, moderate damage, severe damage and serious damage, and comprehensive evaluation indicators are obtained through real-time monitoring. ,in accordance with Determine the threshold range and obtain the current damage degree.

9. A method for analyzing the safety of a sluice structure under cyclic load according to claim 1, characterized in that: In S6, a reliability model is constructed to perform reliability analysis on the sluice structure to obtain the failure probability and reliability index of the structure under cyclic loads, specifically including: The uncertainty of cyclic loading is expressed as a random variable vector Said, the formula is: ,in is the load amplitude, is the load frequency, and the random variable vector Input into the 3D finite element model to construct the limit state function , the formula is: ,in is the structural resistance of the sluice gate, is the cyclic load effect function; the reliability index is calculated by the first-order second moment method , the formula is: ,in and They are The mean and variance of .

10. A method for analyzing the safety of a sluice structure under cyclic load according to claim 1, characterized in that: The above-mentioned S7 comprehensively considers the damage degree and reliability index to establish a safety evaluation system for the sluice structure and makes a graded evaluation, including: Constructing a comprehensive evaluation function , the formula is: ,in is the damage variable of the sluice structure, As a reliable indicator, It is the maximum reliable indicator under ideal conditions; and are the weight coefficients of damage degree and reliability index respectively. The hierarchical analysis method is used to divide the The different safety level intervals corresponding to the values ​​include excellent, good, qualified, warning and dangerous levels. and Substituting into the comprehensive evaluation function, we get Value, according to The range of values ​​determines the safety level of the sluice structure and completes the graded assessment.

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