A Method for Analyzing the Structural Safety of a Sluice under Cyclic Loading

Abstract

The present invention discloses a method for analyzing the structural safety of a sluice under cyclic loads, including: S1, obtaining the basic data of the sluice structure; S2, constructing a three-dimensional finite element model of the sluice structure to simulate the mechanical response of the sluice under actual working conditions; S3, determining the characteristic parameters of the cyclic loads; S4, applying the cyclic loads to the three-dimensional finite element model to obtain the load values of the sluice structure under the action of the cyclic loads; S5, calculating the damage variables of the sluice structure to determine the degree of structural damage; S6, constructing a reliability model to conduct a reliability analysis of the sluice structure to obtain the reliability index of the sluice structure under cyclic loads; S7, establishing a safety evaluation system for the sluice structure and outputting a safety assessment report. The present invention realizes the evaluation of the mechanical response, damage degree and reliability of the sluice structure under cyclic loads, provides a scientific basis for the maintenance and management of the sluice, and ensures the safe and stable operation of the sluice.

Description

Technical Field

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

[0002] As a key facility in water conservancy projects, sluices play a crucial role in flood control, irrigation, shipping, etc. During actual operation, sluice structures are subjected to various complex loads, among which cyclic loads are relatively common and have a significant impact. For example, the periodic rise and fall of water levels, the pulsation of water flows, seismic loads, and the repeated impacts of wind waves will all cause the sluice structure to bear cyclic loads. Under the long-term action of cyclic loads, the stress and strain states inside the sluice structure change continuously, which easily leads to problems such as structural damage and fatigue failure, seriously threatening the safe operation of the sluice. Once a safety problem occurs in the sluice, it will lead to a series of serious consequences such as flood inundation and imbalance in water resource allocation, causing huge losses to people's lives and property and social and economic development. Therefore, accurately analyzing the safety of sluice structures under cyclic loads is of great practical significance for ensuring the reliable operation of sluices and extending their service life.

[0003] Traditionally, when analyzing the safety of sluice structures, methods based on empirical formulas and simplified calculation models are mostly 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 a sluice, only the action of static loads is considered, and the stress and deformation of the structure are estimated through 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 ignoring important factors such as cyclic loads and the nonlinear characteristics of the structure, there is a large deviation between the calculation results and the actual situation, and the safety of the sluice under complex working conditions cannot be accurately evaluated. This leads to misjudgments of the safety performance of the sluice structure, either overestimating the structural safety and leaving potential safety hazards for the project, or underestimating the structural safety and causing unnecessary project reinforcement and investment waste.

[0004] With the development of computer technology and numerical analysis methods, certain progress has been made in the prior art in analyzing the safety of sluice structures. Currently, the finite element analysis method is 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, and the stress and strain distributions of the sluice structure can be simulated more accurately. When considering cyclic loads, some prior arts can perform simple time history analysis to obtain the response of the structure under cyclic loads.

[0005] However, there are still some deficiencies in the existing technologies. On the one hand, when establishing a finite element model, there is a lack of a unified standard for element division and parameter selection, and there are significant differences in the modeling methods of different researchers, resulting in the comparability and reliability of analysis results being affected. On the other hand, when evaluating the safety of the sluice structure, the existing technologies mainly focus 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 give an accurate and comprehensive safety evaluation of the sluice structure.

[0006] Therefore, in view of the above problems, the present application proposes a method for analyzing the safety of a sluice structure under cyclic loads, which solves the above-mentioned technical problems. Summary of the Invention

[0007] Based on the above content, the present application proposes a method for analyzing the safety of a sluice structure under cyclic loads, including the following steps:

[0008] S1. Obtain the basic data of the sluice structure, where the basic data includes the structural design parameters and material property 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. According to the hydrological data and operation records of the area where the sluice is located, determine the characteristic parameters of the cyclic load, including load amplitude, frequency, action duration, and number of cycles;

[0011] S4. Apply the cyclic load to the three-dimensional finite element model and perform time history analysis to obtain the load values of the sluice structure under the cyclic load;

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

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

[0014] S7. Integrate the damage degree and the reliability index to establish a safety evaluation system for the sluice structure, and perform a hierarchical evaluation of the safety of the sluice structure according to this system, and output a safety evaluation report.

[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 unit bodies, which include 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 plate-shell units. The solid units are divided into micro-unit bodies by eight-node hexahedral isoparametric elements to obtain the displacement vectors of the micro-unit bodies. The plate-shell units are divided into micro-unit bodies by four-node thin plate elements to obtain the displacement vectors of the micro-unit bodies. The stress tensors of the solid units and plate-shell units are obtained through an elastoplastic structure model.

[0017] Preferably, the solid units are divided into micro-unit bodies by eight-node hexahedral isoparametric elements to obtain the displacement vectors, specifically including:

[0018] Obtain the displacement vector of any point in the micro-unit body , the formula is: , where is the solid shape function, is the displacement vector of point; Calculate the solid shape function through the local coordinates of the micro-unit body , the formula is: , where is the local coordinates of the micro-unit body at point; Combine the displacement vectors of the micro-unit bodies in the solid unit to obtain the displacement vector of the solid unit.

[0019] Preferably, the plate-shell units are divided into micro-unit bodies by four-node thin plate elements to obtain the displacement vectors, specifically including:

[0020] Obtain the displacement vector of any point in the micro-unit body , the formula is: , where is the displacement vector of point, is the plate-shell shape function, is the rotation angle of point around axis and axis; Calculate the plate-shell shape function through the local coordinates of the micro-unit body, the formula is: , where is the local coordinates of the micro-unit body at point; Combine the displacement vectors of the micro-unit bodies in the plate-shell unit to obtain the displacement vector of the plate-shell unit.

[0021] Preferably, the three-dimensional finite element model is constructed by obtaining the stress tensors and displacement vectors of the solid units and plate-shell units. The stress tensors are obtained through an elastoplastic structure model, specifically:

[0022] Obtain the damage variables of the sluice structure's solid elements and plate-shell elements and the strain tensor , and construct an elastoplastic structural model. The formula is: , where is the stress tensor, is the initial damage variable. Obtain the stress tensors of the solid elements and plate-shell elements . Through the stress tensors of the solid elements and plate-shell elements combined with the displacement vectors of the solid elements and plate-shell elements, construct a three-dimensional finite element model.

[0023] Preferably, in step S4, apply the cyclic load to the three-dimensional finite element model for time history analysis to obtain the load values of the sluice structure under the cyclic load. Specifically:

[0024] Discretize the characteristic parameters of the cyclic load. According to the set time step , divide the action duration of the cyclic load into multiple time nodes . The formula is: , where is the time step value. At each time point, calculate the load value at the current moment according to the load amplitude , frequency and the number of cycles. The formula is: , where is the load correction function adjusted by the number of cycles. The formula is: , where is the total number of time steps, is the number of time steps corresponding to the number of cycles. Obtain the load values of the sluice structure under the cyclic load through the above formula to evaluate the damage degree of the sluice structure.

[0025] Preferably, after obtaining the load values of the sluice structure under the cyclic load in step S5, calculate the damage variables using the structural damage function. The formula is: , where is the load value at the th 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. Calculate the load values corresponding to different regions of the sluice structure through the structural damage function to obtain the damage variables of different regions of the sluice structure .

[0026] Preferably, determine the structural damage degree according to the damage variables of different regions of the sluice structure. Specifically:

[0027] Construct comprehensive evaluation indexes , and the comprehensive evaluation indexes include damage variables and the change rate of damage variables , and the formula is: , where , are the corresponding weight coefficients respectively; set the threshold ranges of under different damage levels, divide into four levels of mild damage, moderate damage, severe damage and serious damage, obtain the comprehensive evaluation indexes through real-time monitoring, and determine the threshold interval where it is located according to to obtain the current damage degree.

[0028] Preferably, in S6, a reliability model is constructed to conduct reliability analysis on the sluice structure, and the failure probability and reliability index of the structure under cyclic load are obtained, specifically including:

[0029] Express the uncertainty of cyclic load with a random variable vector , and the formula is: , where is the load amplitude, is the load frequency, input the random variable vector into the three-dimensional finite element model to construct the limit state function , and the formula is: , where is the resistance of the sluice structure, is the cyclic load effect function; calculate the reliability index through the first-order second-moment method, and the formula is: , where and are respectively the mean and variance of.

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

[0031] Construct a comprehensive evaluation function , and the formula is: , where is the damage variable of the sluice structure, is the reliability index, is the maximum reliability index under the ideal state; and are respectively the weight coefficients of the damage degree and the reliability index, and are divided into The different safety level intervals corresponding to the values, including the five-level intervals of excellent, good, qualified, warning, and dangerous. Substitute the calculated and into the comprehensive evaluation function to obtain the value. Determine the safety level of the sluice structure according to the interval where the value is located, and complete the grading evaluation.

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

[0033] By obtaining the basic data of the sluice structure, constructing a three-dimensional finite element model to simulate the mechanical response under actual working conditions, and then applying cyclic loads for time history analysis, the present invention solves the technical problem that it is difficult for traditional methods to accurately simulate the mechanical state of the sluice under complex cyclic loads, and can accurately obtain the load values of the sluice structure under cyclic loads, providing reliable data support for subsequent evaluation of the structural damage degree and safety. Compared with traditional methods, the accuracy of the mechanical response analysis of the sluice structure is greatly improved.

[0034] By using the structural damage function to calculate the damage variable of the sluice structure, and constructing a comprehensive evaluation index by combining the damage variable and the damage variable change rate to determine the structural damage degree, the present invention solves the technical problem that it is difficult to accurately evaluate the damage degree of the sluice structure under cyclic loads, and can divide the damage degree of the sluice structure into four grades: mild damage, moderate damage, severe damage, and serious damage, realizing the quantitative evaluation of the structural damage state, enabling the management personnel to intuitively understand the damage situation of the sluice, and facilitating the timely adoption of corresponding maintenance or reinforcement measures.

[0035] By representing the uncertainty of cyclic loads with a random variable vector, constructing a limit state function and using the first-order second-moment method to calculate the reliability index, the present invention solves the technical problem that it is difficult to consider the uncertainty of cyclic loads in the safety analysis of the sluice structure, and 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 decisions, and avoid potential safety hazards or over-design caused by ignoring the load uncertainty.

[0036] By constructing a comprehensive evaluation function, combining the damage variable and the reliability index, and using the analytic hierarchy process to divide the safety level intervals, the present invention solves the technical problem that it is difficult for the prior art to comprehensively and accurately evaluate the safety of the sluice structure, divides the safety level of the sluice structure into five levels: excellent, good, qualified, warning, and dangerous, conducts a comprehensive grading evaluation of the sluice safety, outputs a detailed safety evaluation report, facilitates the engineering personnel to comprehensively master the safety status of the sluice, and formulate targeted management and maintenance strategies to 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 understand the technical means of the present application more clearly, so that it can be implemented in accordance with the content of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the following describes in detail with reference to the preferred embodiments of the present application and the accompanying drawings.

[0038] Based on the following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings, those skilled in the art will more clearly understand the above and other purposes, 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 following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

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

[0041] Figure 2 It is a diagram of the division of solid units of a method for analyzing the safety of a sluice structure under cyclic loading according to the present invention;

[0042] Figure 3 It is a diagram of the division of plate and shell units of a method for analyzing the safety of a sluice structure under cyclic loading according to the present invention;

[0043] Figure 4 It is an evaluation output diagram of a method for analyzing the safety of a sluice structure under cyclic loading according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. In the following description, specific details such as specific configurations and components are provided only to help a comprehensive understanding of the embodiments of the present application. Therefore, those skilled in the art should clearly understand that various changes and modifications can be made to the embodiments described here without departing from the scope and spirit of the present application. In addition, descriptions of known functions and structures are omitted for clarity and conciseness.

[0045] It should be understood that the "one embodiment" or "the present embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, the "one embodiment" or "the present embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner.

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

[0047] The term "and / or" in this article is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another relationship between associated objects, indicating that there can be two relationships. For example, A / and B can represent: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

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

[0049] It should also be noted that in this article, relational terms such as first and second 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 "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion.

[0050] Embodiment 1

[0051] This embodiment mainly describes a method for analyzing the structural safety of a sluice under cyclic loading, as Figure 1 shown, including the following steps:

[0052] S1. Obtain the basic data of the sluice structure, where the basic data includes the structural design parameters and material property parameters of the sluice;

[0053] 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;

[0054] S3. Determine the characteristic parameters of the cyclic load, including the 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. Apply the cyclic load to the three-dimensional finite element model and conduct a time history analysis to obtain the load values of the sluice structure under the cyclic load;

[0056] S5. Calculate the damage variable of the sluice structure using the structural damage function based on the load values and determine the damage degree of the structure;

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

[0058] S7. Establish a safety evaluation system for the sluice structure by integrating the damage degree and the reliability index, conduct a hierarchical assessment of the safety of the sluice structure according to this system, and output a safety evaluation report.

[0059] Furthermore, the construction of the three-dimensional finite element model of the sluice structure in S2 specifically includes:

[0060] Divide the sluice structure into multiple unit bodies, where the multiple unit bodies include solid elements and plate-shell elements. Construct a three-dimensional finite element model of the sluice structure by obtaining the displacement vectors and stress tensors of the solid elements and plate-shell elements; the solid elements are divided into micro-unit bodies through eight-node hexahedral isoparametric elements to obtain the displacement vectors of the micro-unit bodies; the plate-shell elements are divided into micro-unit bodies through four-node thin plate elements to obtain the displacement vectors of the micro-unit bodies; the stress tensors of the solid elements and plate-shell elements are obtained through an elastoplastic structural model.

[0061] Furthermore, the solid elements are divided into micro-unit bodies through eight-node hexahedral isoparametric elements to obtain the displacement vectors, specifically including:

[0062] Obtain the displacement vector of any point in the micro-unit body , and the formula is: , where is the solid shape function, is the displacement vector of point Calculate the solid shape function through the local coordinates of the micro-unit body, and the formula is: where is the local coordinate of point

[0063] in the micro-unit body of the solid element; Combine the displacement vectors of the micro-unit bodies in the solid element to obtain the displacement vector of the solid element.

[0064] Obtain the displacement vector of any point in the micro - element , and the formula is: , where is the displacement vector of point is the plate - shell shape function is the rotation angles of point about the axis and axis; Calculate the plate - shell shape function through the local coordinates of the micro - element, and the formula is: where are the local coordinates of the micro - element at point; Combine the displacement vectors of the micro - elements in the plate - shell element to obtain the displacement vector of the plate - shell element.

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

[0066] Obtain the damage variables and strain tensors of the sluice structure's solid elements and plate - shell elements, and construct the elastoplastic structural model. The formula is: , where is the stress tensor is the initial damage variable, obtain the stress tensors of the solid elements and plate - shell elements, and combine the stress tensors of the solid elements and plate - shell elements with the displacement vectors of the solid elements and plate - shell elements to construct the three - dimensional finite - element model.

[0067] Furthermore, in S4, cyclic loads are applied to the three - dimensional finite - element model for time - history analysis to obtain the load values of the sluice structure under cyclic loads, specifically:

[0068] Discretize the characteristic parameters of the cyclic loads. According to the set time step , divide the action duration of the cyclic loads into multiple time nodes , and the formula is: , where is the time - step value; At each time point, calculate the load value at the current moment according to the load amplitude , frequency , and the number of cycles. The formula is: , where is the load correction function adjusted by the number of cycles, and the formula is: , where 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 cyclic loading is obtained through the above formula to evaluate the damage degree of the sluice structure.

[0069] Further, after obtaining the load value of the sluice structure under cyclic loading in S5, the damage variable is calculated using the structural damage function, and the formula is: , where is the load value at the th time step, is the time cumulative weight coefficient, is the bearing capacity of the sluice structure, is the non-linear coefficient of the sluice structure, is the total number of time steps; the load values corresponding to different regions of the sluice structure are calculated through the structural damage function to obtain the damage variables of different regions of the sluice structure .

[0070] Further, the damage degree of the structure is determined according to the damage variables of different regions of the sluice structure, specifically:

[0071] Construct a comprehensive evaluation index , and the comprehensive evaluation index includes the damage variable and the damage variable change rate , and the formula is: , where , are the corresponding weight coefficients respectively; set the threshold ranges of under different damage levels, divide them into four levels: mild damage, moderate damage, severe damage and serious damage, obtain the comprehensive evaluation index through real-time monitoring, and determine the threshold interval where it is located according to to obtain the current damage degree.

[0072] Further, in S6, a reliability model is constructed to perform reliability analysis on the sluice structure, and the failure probability and reliability index of the structure under cyclic loading are obtained, specifically including:

[0073] The uncertainty of the cyclic load is represented by the random variable vector , and the formula is: , where is the load amplitude, is the load frequency, and the random variable vector is input into the three-dimensional finite element model to construct the limit state function , and the formula is: , where is the resistance of the sluice structure, is the cyclic load effect function; the reliability index is calculated by the first-order second-moment method , and the formula is: , where and are respectively the mean value and variance of

[0074] Furthermore, in S7, a safety evaluation system for the sluice structure is established based on the comprehensive damage degree and the reliability index, and graded evaluation is carried out, specifically including:

[0075] Construct a comprehensive evaluation function , and the formula is: , where is the damage variable of the sluice structure, is the reliability index, is the maximum reliability index under the ideal state; and are respectively the weight coefficients of the damage degree and the reliability index. According to historical data and engineering standards by the analytic hierarchy process, different safety level intervals corresponding to the value are divided, including five-level intervals of excellent, good, qualified, warning, and dangerous. Substitute the calculated and into the comprehensive evaluation function to obtain the value, and determine the safety level of the sluice structure according to the interval where the value is located, and complete the graded evaluation.

[0076] This embodiment details constructing a three-dimensional finite element model by obtaining the basic data of the sluice structure, simulating the mechanical response under actual working conditions, determining the cyclic load characteristic parameters and applying them to the model for time history analysis, calculating the damage variable using the structural damage function, constructing a reliability model to analyze the reliability, and then establishing a safety evaluation system, solving the problem of inaccurate safety assessment of the sluice under cyclic loads, accurately analyzing the mechanical response, damage degree and reliability of the sluice structure, realizing safety graded evaluation, outputting an evaluation report, providing a scientific basis for the maintenance and management of the sluice, and ensuring the safe and stable operation of the sluice.

[0077] Based on Embodiment 1, this embodiment describes dividing the sluice structure into multiple unit bodies. The multiple unit bodies include solid elements and plate-shell elements. The solid elements are divided into micro-unit bodies by eight-node hexahedral isoparametric elements, and the plate-shell elements are divided into micro-unit bodies by four-node thin plate elements. Specifically:

[0078] As Figure 2As shown in the figure, the solid elements are divided into micro - element bodies by eight - node hexahedral isoparametric elements. When choosing eight - node hexahedral isoparametric elements to divide the solid elements, from the perspective of geometric adaptability, the shape of the eight - node hexahedron is regular and flexible, and it can better fit various complex solid shapes in the sluice structure. The foundation and the solid part of the pier of the sluice often have irregular outer shapes and complex internal structures. The eight - node hexahedral isoparametric elements can accurately discretize these areas through reasonable arrangement and combination, minimizing the error caused by the mismatch between the element shape and the actual structure to the greatest extent.

[0079] In terms of mechanical property simulation, the eight - node hexahedral isoparametric element has high precision. The mechanical properties of the element are described by eight nodes, reflecting the stress - strain distribution inside the element. Compared with some simple element division methods, the eight - node hexahedral isoparametric element can better capture the mechanical response under complex stress states. When the sluice is subjected to cyclic loads, complex stress changes will occur inside the structure. The eight - node hexahedral isoparametric element can simulate these changes more meticulously, providing strong support for accurately evaluating the safety of the sluice structure. In addition, the eight - node hexahedral isoparametric element has good stability in the calculation process. Its mathematical model and calculation method are relatively mature, ensuring the calculation efficiency and result reliability in large - scale finite - element analysis.

[0080] As Figure 3 shown in the figure, the plate - shell elements are divided into micro - element bodies by four - node thin - plate elements. Using four - node thin - plate elements to divide the plate - shell elements is based on the mechanical characteristics and analysis requirements of the plate - shell structure. The plate - shell structure in the sluice mainly bears bending and shear loads, and the four - node thin - plate element can well adapt to this mechanical property. Geometrically, the shape of the four - node thin - plate element is simple and easy to arrange on the plate - shell structure, and it can flexibly simulate various shapes of plate - shells. 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 elements.

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

[0082] This embodiment details the precise simulation of the mechanical response of a sluice structure by dividing it into solid and plate-shell elements, which are further subdivided using eight-node hexahedral isoparametric elements and four-node thin plate elements respectively, capturing the stress and strain of the sluice under cyclic loads, accurately calculating the damage variable and reliability index, and then establishing a comprehensive safety evaluation system. Ultimately, it realizes the scientific evaluation of the safety of the sluice structure, provides strong support for the decision-making of sluice maintenance and reinforcement, ensures the safe and stable operation of the sluice, reduces potential risks, and extends the service life of the sluice.

[0083] Based on Embodiment 1, this embodiment details the establishment of a safety evaluation system for the sluice structure according to the damage degree and reliability index and its hierarchical evaluation, as Figure 4 shown, specifically as follows:

[0084] The sluice structure evaluation system includes the setting of damage grades and safety grade intervals; the damage grade reflects the actual damage degree of the sluice structure under cyclic loads by analyzing the damage variable and its change rate, reflecting the current physical state of the structure; the safety grade interval takes into account the structural damage situation and reliability index, measuring the safety and reliability of the sluice under various uncertain factors, which is a comprehensive judgment of the overall safety of the sluice.

[0085] Establish the corresponding relationship between the damage grade and the safety grade interval. Under the mild damage grade, if the reliability index is relatively high, the calculated value is in the excellent or good interval, which means that although the sluice has minor damage, its overall safety is still relatively high, and only routine inspections and maintenance are required; when the damage is moderate, the value may fall into the qualified interval, indicating that although the structure has certain damage, it is still within the acceptable range, but the monitoring frequency needs to be increased, and repair work should be arranged in a timely manner. If the damage is severe, the value is in the warning interval, at this time the structural damage is relatively serious, and the safety risk increases significantly, and a detailed reinforcement plan must be formulated as soon as possible. In the case of severe damage, the value must be in the dangerous interval, and the sluice can no longer operate normally, and urgent emergency rescue measures need to be taken, and even reconstruction should be considered.

[0086] In actual operation, these two evaluation results can be flexibly applied according to different evaluation purposes and scenarios. For daily inspections, priority is given to the damage level, which can quickly determine whether there are abnormal damages to the sluice. Once it is found that the damage level increases, a comprehensive analysis shall be immediately carried out in combination with the safety level range. If the safety level also decreases accordingly, it indicates that the problem is relatively serious and more resources need to be invested for treatment. When upgrading the safety evaluation or making long-term plans for the sluice, the safety level range shall be taken as the core, and the damage level shall be referred to to understand the historical damage development of the structure, providing a basis for subsequent reinforcement, transformation and life prediction. By organically combining the damage level and the safety level range in this way, a hierarchical, comprehensive and effective evaluation system can be formed, providing a solid guarantee for the safe and stable operation of the sluice and ensuring the continuous exertion of the functions of the water conservancy project.

[0087] This embodiment details the combination of the sluice structure damage level and the safety level range, avoiding repeated evaluations and providing key information for sluice evaluation from multiple dimensions. By establishing a corresponding relationship and flexibly applying the evaluation results in daily inspections and long-term plans, the sluice condition can be quickly judged, providing a scientific basis for maintenance and reinforcement decisions, ensuring the safe and stable operation of the sluice, and ensuring the continuous exertion of the functions of the water conservancy project.

[0088] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby. For those skilled in the art, various changes and modifications can be made to the present invention; within the spirit and principle of the present invention, any changes, modifications, substitutions, integrations and parameter changes made to these embodiments by means of conventional substitutions or capable of achieving the same functions without departing from the principle and spirit of the present invention fall within the protection scope 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 sluice structure safety evaluation system is established, and the safety of the sluice structure is graded and evaluated according to the system, and a safety evaluation report is output; 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 ; 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 .

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 number of time steps corresponding to the number of cycles; The load value of the sluice structure under 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, 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.

8. 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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