Method for setting and controlling buckle cable adjustment threshold value in large-span arch bridge hoisting construction

Abstract

The invention discloses a method for setting and controlling a buckle cable adjustment threshold value in large-span arch bridge hoisting construction, which comprises the following steps of: acquiring construction parameters of a current buckle section, and acquiring a corresponding cable adjustment target value; constructing a structural mechanics finite element model of the target buckle cable based on the construction parameters, and introducing a buckle cable multi-harness nonlinear stress mechanism into the model to calculate upper and lower limit thresholds of cable force in the tensioning process; determining an elevation adjustment threshold according to the target axis, the target elevation, the accumulated deviation and the pre-deformation compensation amount in combination with a geometric linear control model; and generating an environmental influence correction coefficient by utilizing construction environmental parameters, and dynamically correcting the cable force and the elevation threshold value to realize real-time updating of the threshold value in the hoisting process. According to the method, the problems of nonlinearity of multiple wire harnesses of the large-span arch bridge buckle cable, high linear sensitivity of the arch rib, remarkable environmental influence and the like are solved, high-precision cooperation of cable force control and linear control is realized, and the safety, controllability and construction efficiency of hoisting construction are improved.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, and in particular to a method for setting and controlling the adjustment threshold of the cable in the hoisting construction of a long-span arch bridge. Background Technology

[0002] In the cantilever construction of long-span arch bridges, cable adjustment is a crucial step to ensure that the arch rib alignment and elevation meet design requirements and that the structure is safe during construction. Traditional cable adjustment relies on construction personnel using multiple jacks and hydraulic pumps to perform synchronous, symmetrical, and graded tensioning operations based on target values ​​for cable tension, arch rib elevation, and adjustment sequence jointly provided by the designer and construction monitoring team. During this process, it is necessary to use a spectrum analyzer to test cable tension in real time and manually monitor changes in the arch rib axis and elevation to avoid cumulative errors that could lead to difficulties in the final adjustment.

[0003] However, this adjustment method, which relies on manual experience, has the following shortcomings: First, the control thresholds for cable force and elevation during the cable adjustment process are mostly set based on experience, lacking dynamic and precise quantitative basis, and are easily affected by human factors, which may lead to insufficient adjustment accuracy or over-adjustment, affecting construction efficiency and structural safety; Second, manual monitoring and judgment of the timing and magnitude of adjustments have a slow response speed, making it difficult to adapt to the dynamic adjustment needs caused by changes in load, temperature and other factors in complex construction environments; Third, the setting of adjustment thresholds for each section is not effectively linked to the cumulative error of the preceding section and the pre-deformation compensation of subsequent construction, which may increase the difficulty of overall alignment control.

[0004] Therefore, there is an urgent need for a method for setting and controlling the cable adjustment threshold in the hoisting construction of long-span arch bridges, which can improve the automation level, control accuracy and construction safety of cable adjustment operations in long-span arch bridges. Summary of the Invention

[0005] In view of this, the present invention provides a method for setting and controlling the cable adjustment threshold in the hoisting construction of a long-span arch bridge, in order to solve the technical problems of existing cable adjustment threshold setting relying on manual experience, resulting in insufficient control accuracy and untimely response.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: On one hand, this invention provides a method for setting and controlling the adjustment threshold of the sling in the hoisting construction of a long-span arch bridge, including... The construction parameters of the target cable under hoisting status are acquired in real time and the data is preprocessed. The construction parameters include: the current hoisting segment number, the initial cable force of the current cable segment, the initial axis coordinates of the arch rib, the initial elevation value, and the construction environment parameters. Obtain the target cable force value, target arch rib axis coordinates, target elevation value, and cable adjustment sequence command for the current cable segment; A structural mechanics finite element model of the target cable is established. Based on the structural mechanics finite element model, the upper and lower threshold values ​​of cable force adjustment are calculated according to the construction parameters and the target cable force value. A nonlinear force model based on the multi-strand properties of the cable is introduced into the structural mechanics finite element model. Based on the geometric alignment control model, the upper and lower threshold values ​​for elevation adjustment are calculated according to the target arch rib axis coordinates, target elevation value, previous cumulative deviation, and pre-deformation compensation value. The environmental impact correction coefficient is determined based on the construction environment parameters, and the cable force threshold and elevation threshold are dynamically corrected according to the environmental impact correction coefficient to obtain the dynamically corrected threshold. The measured values ​​of cable force and elevation monitored in real time are compared with the dynamically corrected thresholds, and tension control commands are generated and executed according to the cable adjustment sequence commands. After each adjustment operation is completed, the actual adjustment data is stored in the database. The threshold calculation model is iteratively optimized through machine learning models, and the values ​​of each model coefficient are updated.

[0007] Furthermore, the method for constructing the nonlinear force model includes: Obtain the material constitutive parameters and nonlinear influence parameters of the target cable strand; Based on the theory of curvilinear tension friction, nonlinear influence parameters are integrated into the stress-strain relationship of the cable element, and a decay function of cable force along the cable length is established to simulate the non-uniformity of cable force caused by friction in each strand during the tensioning process. A time-varying creep model was introduced to establish the relationship between creep strain, tension holding time, and initial stress, which was used to predict and correct cable force loss in subsequent construction stages. Based on historical data, the initial tension of multiple wire bundles or the uneven initial cable force caused by stress relaxation at the anchorage is quantified within the normal construction error range. Based on the initial non-uniform cable force value, and according to the attenuation function and creep model, the deviation between the final cable force of each strand under nonlinear influence and the theoretical average cable force is calculated under the action of the target cable force, and the nonlinear cable force correction value is obtained.

[0008] Furthermore, the method for establishing the structural mechanics finite element model of the target cable includes: The structural mechanics finite element model serves as the macroscopic framework model of the full-bridge structure. The updated Lagrange method is used to initiate the geometric nonlinear analysis of the arch ribs. Based on the current deformation configuration, the overall structural equilibrium equation is established to ensure accurate tracking of structural stiffness changes under long-span cantilever conditions. The arch rib section characteristics, cable material properties, and temporary tower information corresponding to the current hoisting segment number are used as the geometric and material input parameters of the finite element model, and the initial value of the cable force is used as the initial state input data. The nonlinear force model is embedded in the finite element framework as a nonlinear constitutive model of the cable element, in order to replace the simple linear material properties of the cable element.

[0009] Furthermore, the calculation method for the upper and lower thresholds of the cable tension adjustment includes: in, Indicates the upper limit threshold of cable force. This indicates the lower limit threshold of cable tension. Indicates the target cable force value. This indicates the allowable cable tension deviation rate during construction monitoring. Indicates the structural safety reserve factor. This represents the force distribution correction term caused by uneven stress relaxation when the i-th strand reaches the target force. This indicates the number of strands in the cable.

[0010] Furthermore, the geometric line control model includes a cumulative deviation tracking unit, a dynamic sensitivity calculation unit, and an elevation calculation unit; The cumulative deviation tracking unit is used to calculate and store the cumulative elevation deviation and cumulative axis deviation between the actual adjustment deviation and the target deviation of all previous segments based on the initial axis coordinates of the arch rib, the initial elevation value, the target arch rib axis coordinates and the target elevation value. The dynamic sensitivity calculation unit is used to calculate the dynamic geometric sensitivity coefficient of the arch rib and to calculate the influence rate of the slight change in cable force on the elevation based on the current stiffness of the cantilever. The elevation calculation unit is used to superimpose the static displacement compensation and the dynamic safety tolerance onto the target elevation value to obtain the final elevation adjustment threshold.

[0011] Furthermore, the upper and lower threshold values ​​for calculating the elevation adjustment include: in, This indicates the upper limit threshold for elevation adjustment. This indicates the lower limit threshold for elevation adjustment. Indicates the target elevation value. Indicates the pre-deformation compensation value. Indicates the allowable design deviation. Indicates the cumulative elevation deviation of the preceding sequence. This represents the dynamic geometric sensitivity coefficient of the arch rib. This indicates the dynamic safety tolerance of the cable force.

[0012] Furthermore, the determination of the environmental impact correction coefficient based on construction environment parameters includes: in, This represents the overall correction factor. This represents the uniform temperature correction factor. , This represents the coefficient of linear expansion of the material. This indicates the change in average ambient temperature. This represents the temperature gradient correction factor. This represents the wind speed correction factor. β represents the wind load influence coefficient. Indicates real-time wind speed. This represents the creep correction factor, used to correct for the decrease in cable force over time caused by the stress creep effect of the cable material.

[0013] Furthermore, generating and executing tension control commands based on the cable adjustment sequence commands includes: The PID control algorithm is used to dynamically calculate the tension adjustment amount based on the real-time cable force deviation, and the drive parameters of the jack oil pump system are adjusted accordingly. The calculation formula for the PID control algorithm is as follows: in, To dynamically adjust the increment of the output tension force, This represents the cable force deviation, which is the difference between the dynamically corrected cable force threshold at the current moment and the real-time monitored measured cable force value. , , These are the preset proportional coefficient, integral coefficient, and differential coefficient, respectively.

[0014] Furthermore, the machine learning model is a BP neural network, and it outputs the effective value correction of the elastic modulus of the cable in real time based on multi-dimensional input features, so as to dynamically update the cable force threshold calculation model. The multidimensional input features include at least: cable force deviation rate, elevation deviation, tensioning step length, ambient temperature, and historical extension.

[0015] On the other hand, the present invention also provides a cable adjustment threshold setting and control system for the hoisting construction of a long-span arch bridge, comprising: The data acquisition module is used to acquire the construction parameters of the target cable in the hoisting state in real time and to preprocess the data. The construction parameters include: the current hoisting segment number, the initial cable force of the current cable segment, the initial axis coordinates of the arch rib, the initial elevation value, and the construction environment parameters. The communication module is used to obtain the target cable force value, target arch rib axis coordinates, target elevation value, and cable adjustment sequence command for the current cable segment. The cable force threshold calculation module is used to establish a structural mechanics finite element model of the target cable, and calculate the upper and lower thresholds of cable force adjustment based on the construction parameters and the target cable force value according to the structural mechanics finite element model; wherein, a nonlinear force model based on the multi-bundle properties of the cable is introduced into the structural mechanics finite element model; The elevation threshold calculation module is used to calculate the upper and lower thresholds for elevation adjustment based on the geometric alignment control model, according to the target arch rib axis coordinates, target elevation value, previous cumulative deviation, and pre-deformation compensation value. The environmental factor calculation module is used to determine the environmental impact correction factor based on the construction environmental parameters, and to dynamically correct the cable force threshold and elevation threshold according to the environmental impact correction factor to obtain the dynamically corrected threshold. The control module is used to compare the real-time monitored cable force and elevation measured values ​​with the dynamically corrected threshold, and generate and execute tension control commands according to the cable adjustment sequence command; The feedback optimization module is used to store the actual adjustment data in the database after each deduction segment adjustment operation is completed, and to iteratively optimize the threshold calculation model through a machine learning model to update the values ​​of each model coefficient.

[0016] Compared with existing technologies, the method for setting and controlling the cable adjustment threshold in the hoisting construction of long-span arch bridges proposed in this invention has the following advantages: (1) By collecting the construction parameters of the cable under hoisting conditions in real time, and combining the finite element model of structural mechanics with the nonlinear stress characteristics of the cable multi-strand, the upper and lower threshold values ​​for cable force adjustment were dynamically calculated. Compared with the traditional method that relies on static empirical values ​​or linear assumptions, this invention can more accurately reflect the real mechanical behavior of the cable under complex stress conditions, effectively avoid over- or under-tensioning caused by improper threshold setting, and thus significantly improve the safety and construction control accuracy of the arch bridge hoisting process.

[0017] (2) Introducing geometric alignment control and environmental effect correction to improve the adaptability and robustness of the construction process. This invention is based on geometric alignment control theory, combining the target arch rib axis coordinates, target elevation, cumulative deviation, and pre-deformation compensation to construct a dynamic calculation mechanism for the elevation adjustment threshold. Simultaneously, an environmental impact correction coefficient is constructed using construction environment parameters to dynamically correct the cable force and elevation threshold, enabling the calculation model to adapt to changes in external environment such as temperature and humidity. This technical approach significantly enhances the adaptability and robustness of hoisting construction control, making the threshold judgment more closely aligned with actual working conditions and avoiding control deviations caused by environmental disturbances.

[0018] (3) By storing the actual adjustment data of each cable segment in a database, and using a machine learning model to iteratively optimize the calculation models for cable force threshold and elevation threshold, adaptive updates of key model parameters (including nonlinear force model parameters, environmental correction coefficients, cable force threshold model coefficients, etc.) are achieved. Compared with traditional static models, this invention can continuously improve model accuracy as the construction process progresses, making the generation of control commands more intelligent and personalized, and effectively improving the stability, accuracy, and construction quality of cable adjustment during the overall hoisting construction process. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the method for setting and controlling the cable adjustment threshold during the hoisting construction of a long-span arch bridge provided by the present invention. Figure 2 This is a schematic diagram of the structure of the cable adjustment threshold setting and control system for the hoisting construction of a large-span arch bridge provided by the present invention. Detailed Implementation

[0020] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0021] Before introducing the embodiments of the present invention, the difficulties in the design of the cable-stayed bridge for long-span arch bridges will be explained first.

[0022] The installation of long-span arch bridges plays a crucial role in the construction phase. Cable tie designs not only bear temporary construction loads but also precisely control the axis, elevation, and pre-deformation of the arch ribs, serving as a key means of temporary load-bearing structure and alignment control. In long-span arch bridges, due to the heavy self-weight of the arch ribs and the long cantilever length, the cable tie needs to provide enormous tension to balance the moment and weight. Furthermore, compared to ordinary arch bridge designs, long-span arch bridges have a larger number of cable tie systems, finer segmentation, and greater variation in cable length. To accommodate long cantilever and segmented assembly (such as the division into multiple tie segments mentioned in the instructions), cable tie systems are typically set in multiple levels and pairs, forming complex cable groups. To ensure control stability, the cable tie strands usually have a large number of bundles, high strength, and good durability, with strict requirements on elastic modulus and creep characteristics. Therefore, the cable tie system design for long-span arch bridges is a high-precision, high-load-bearing, and complex temporary structural design that needs to be highly integrated with precise alignment control during construction (such as pre-deformation and cumulative error compensation).

[0023] Example 1 Please see Figure 1 This embodiment provides a method for setting and controlling the adjustment threshold of the sling during the hoisting construction of a long-span arch bridge, including the following steps: Step S101: Real-time acquisition of construction parameters of the target cable under hoisting status, and preprocessing of the data; the construction parameters include: current hoisting segment number, initial cable force value of the current cable segment, initial axis coordinates of the arch rib, initial elevation value, and construction environment parameters; Step S102: Obtain the target cable force value, target arch rib axis coordinates, target elevation value, and cable adjustment sequence command for the current cable segment; Step S103: Establish a structural mechanics finite element model of the target cable, and calculate the upper and lower threshold values ​​of the cable force adjustment based on the construction parameters and the target cable force value according to the structural mechanics finite element model; wherein, a nonlinear force model based on the multi-strand properties of the cable is introduced into the structural mechanics finite element model; Step S104: Based on the geometric line control model, calculate the upper and lower thresholds for elevation adjustment according to the target arch rib axis coordinates, target elevation value, previous cumulative deviation and pre-deformation compensation value; Step S105: Determine the environmental impact correction coefficient based on the construction environment parameters, and dynamically correct the cable force threshold and elevation threshold according to the environmental impact correction coefficient to obtain the dynamically corrected threshold. Step S106: Compare the real-time monitored cable force and elevation measurements with the dynamically corrected thresholds, and generate and execute tension control commands according to the cable adjustment sequence commands; Step S107: After each segment adjustment operation is completed, the actual adjustment data is stored in the database, and the threshold calculation model is iteratively optimized through the machine learning model to update the values ​​of each model coefficient.

[0024] The method in this embodiment first obtains the construction parameters of the current cable segment and the corresponding cable adjustment target value. Based on the construction parameters, a structural mechanics finite element model of the target cable is constructed, and a nonlinear force mechanism of multiple cable bundles is introduced into the model to calculate the upper and lower limit thresholds of cable force during the tensioning process. Then, combined with the geometric alignment control model, the elevation adjustment threshold is determined according to the target axis, target elevation, cumulative deviation, and pre-deformation compensation amount. Next, environmental impact correction coefficients are generated using construction environment parameters to dynamically correct the cable force and elevation thresholds, realizing real-time updating of thresholds during the hoisting process.

[0025] As a specific embodiment, in step S101, during the arch rib hoisting construction, after the cable of each section is installed, the initial value of the cable force of the current cable, the initial axis coordinates of the arch rib, and the initial elevation value are collected in real time by sensors; at the same time, construction environment parameters, including ambient temperature, wind speed, and solar radiation intensity, are collected; the collected data are preprocessed by filtering, noise reduction, and outlier removal to ensure data validity.

[0026] For example, when constructing a steel box arch bridge with a main span of 300m using the cantilever assembly method, it is divided into 15 sections. Each section is equipped with 4 pairs of tension cables, and each pair of tension cables consists of 8 bundles of steel strands. Two 200t jacks are used for symmetrical tensioning.

[0027] After the fifth section of the cable was installed, the data acquisition module was activated. The cable force sensor collected the initial cable force values ​​of the four pairs of cables in real time, which were 500kN, 510kN, 495kN, and 505kN, respectively. The displacement sensor measured the initial X-coordinate of the arch rib axis as 150.234m, the Y-coordinate as 0.021m, and the initial elevation as 85.678m. The environmental sensor measured the current temperature as 25℃, the wind speed as 2m / s, and the solar radiation intensity as 600W / m². 2 The data processing module filters the above data to remove abnormal fluctuations caused by sensor vibration.

[0028] In some embodiments, when collecting the initial cable force value, additionally collecting the stress relaxation rate or creep strain rate at the cable anchor (or steel strand) can make the initial cable force calculated by the subsequent model more realistic, the time effect prediction more accurate, and the cable performance degradation can be detected in advance, thereby improving the accuracy and safety of cable threshold setting and tension control.

[0029] As a specific embodiment, in step S102, the target cable force value, target arch rib axis coordinates, and target elevation value of the current cable section, as well as the cable adjustment sequence instruction, are received from the designer and construction monitoring party through the data interface.

[0030] For example: The target cable force value for the 5th cable section received from the construction monitoring center is 650kN (per pair of cables), the target axis X coordinate is 150.000m, the Y coordinate is 0.000m, the target elevation is 85.700m, and the cable adjustment sequence is symmetrical tensioning from upstream to downstream.

[0031] In a preferred embodiment, step S103, the method for constructing the nonlinear force model includes: Obtain the material constitutive parameters and nonlinear influence parameters of the target cable strand; Based on the theory of curvilinear tension friction, nonlinear influence parameters are integrated into the stress-strain relationship of the cable element, and a decay function of cable force along the cable length is established to simulate the non-uniformity of cable force caused by friction in each strand during the tensioning process. A time-varying creep model was introduced to establish the relationship between creep strain, tension holding time, and initial stress, which was used to predict and correct cable force loss in subsequent construction stages. Based on historical data, the initial tension of multiple wire bundles or the uneven initial cable force caused by stress relaxation at the anchorage is quantified within the normal construction error range. Based on the initial non-uniform cable force value, and according to the attenuation function and creep model, the deviation between the final cable force of each strand under nonlinear influence and the theoretical average cable force is calculated under the action of the target cable force, and the nonlinear cable force correction value is obtained.

[0032] It should be noted that the nonlinear stress model does not analyze the entire bridge, but rather accurately simulates the local nonlinearity and actual cable force distribution caused by friction, uneven stress relaxation, or nonlinear stress-strain relationships in multiple steel strands during tensioning. Embedding the nonlinear stress model into the structural mechanics finite element analysis model for overall nonlinear analysis can be used to calculate the theoretical cable force variation curve from the initial cable force value to the target cable force value.

[0033] As a preferred embodiment, the method for establishing the structural mechanics finite element model of the target cable includes: The structural mechanics finite element model serves as the macroscopic framework model of the full-bridge structure. The updated Lagrange method is used to initiate the geometric nonlinear analysis of the arch ribs. Based on the current deformation configuration, the overall structural equilibrium equation is established to ensure accurate tracking of structural stiffness changes under long-span cantilever conditions. The arch rib section characteristics, cable material properties, and temporary tower information corresponding to the current hoisting segment number are used as the geometric and material input parameters of the finite element model, and the initial value of the cable force is used as the initial state input data. The nonlinear force model is embedded in the finite element framework as a nonlinear constitutive model of the cable element, in order to replace the simple linear material properties of the cable element.

[0034] The structural mechanics finite element model is a three-dimensional macroscopic framework model of the entire long-span arch bridge system. Based on the bridge design parameters, beam elements, shell elements, and truss elements are used to discretize and model the arch ribs, temporary towers, and other structural components to accurately reflect the geometric and material properties of the structure. An updated Lagrangian formulation is used to initiate geometric nonlinear analysis, establishing the overall equilibrium equations of the structure based on the current deformation configuration. This setting is used to eliminate calculation errors caused by large displacements and rotations of the long-span arch ribs during cantilever installation, ensuring that the tangent stiffness matrix of the structure can be updated in real time under long cantilever conditions.

[0035] During tension control, the main thresholds that need to be adjusted include the cable force threshold and the elevation threshold. The calculation methods for each are described below: a. Cable force threshold calculation: Based on the finite element analysis model of structural mechanics, the structural parameters of the current cable segment (including the cross-sectional characteristics of the arch rib, the number of strands of the cable strands, and the elastic modulus), the preload, and the initial state data after preprocessing in step S101 are input to calculate the theoretical cable force change curve during the process of tensioning the cable from the initial cable force value to the target cable force value. Based on the allowable cable force deviation rate (set to ±3%) and the structural safety reserve factor (set to 1.15) during construction monitoring, the upper and lower threshold values ​​for cable force adjustment are automatically calculated. The calculation methods for the upper and lower thresholds of cable tension adjustment include: in, Indicates the upper limit threshold of cable force. This indicates the lower limit threshold of cable tension. Indicates the target cable force value. This indicates the allowable cable tension deviation rate for construction monitoring; in practical applications, the deviation rate is set to ±3%. This represents the structural safety reserve factor, which is set to 1.15 in practical applications; This represents the force distribution correction term caused by uneven stress relaxation when the i-th strand reaches the target force. This indicates the number of strands in the cable.

[0036] b. Elevation Threshold Calculation: Based on the geometric alignment control model, combined with the cumulative axis deviation and elevation deviation values ​​of all previous segments, and the pre-deformation compensation value of the current segment under subsequent construction loads (obtained through construction process simulation prediction), the allowable deviation range of the target elevation for the current segment is calculated. The upper and lower thresholds for elevation adjustment include: in, This indicates the upper limit threshold for elevation adjustment. This indicates the lower limit threshold for elevation adjustment. Indicates the target elevation value. Indicates the pre-deformation compensation value. Indicates the allowable design deviation. Indicates the cumulative elevation deviation of the preceding sequence. This represents the dynamic geometric sensitivity coefficient of the arch rib. This indicates the dynamic safety tolerance of the cable tension, with the allowable deviation range set at ±5mm according to design requirements.

[0037] It should be noted that, The product term is used to construct dynamic safety tolerances, primarily to prevent over-tensioning (cable force upper limit control) and to prevent elevation spikes (elevation upper limit control). The lower threshold is used to trigger tensioning or control the elevation from becoming too low; its calculation is relatively simple, requiring only that it not be lower than the design tolerance. Pre-deformation compensation value. Predict the deformation (usually settlement, indicated by a plus sign, representing the need for current elevation adjustment to compensate for future settlement) caused by subsequent loads using a finite element model. Safety boundary terms. This indicates that the minimum allowable elevation is obtained by subtracting the maximum allowable deviation (e.g., 5mm) from the corrected ideal elevation centerline.

[0038] Furthermore, to ensure that the threshold setting remains accurate, safe, and timely under complex and ever-changing construction environments, this application introduces an environmentally adaptive control method. This method determines the environmental impact correction coefficient based on construction environment parameters, specifically: in, This represents the overall correction factor. This represents the uniform temperature correction factor. , This represents the coefficient of linear expansion of the material. This indicates the change in average ambient temperature. This represents the temperature gradient correction factor. This represents the wind speed correction factor. β represents the wind load influence coefficient. Indicates real-time wind speed. This represents the creep correction factor, used to correct for the decrease in cable force over time caused by the stress creep effect of the cable material.

[0039] It should be noted that the uniform temperature correction factor This is to compensate for the impact of overall thermal expansion and contraction on the cable force reference; that is, the overall heating or cooling of the arch rib section causes uniform thermal expansion and contraction of the arch rib structure, resulting in changes in its length and the overall change in the cable force. The temperature gradient correction coefficient... This is to compensate for the impact of this non-uniform deformation on the arch rib's shape and elevation threshold, primarily due to uneven heating of the arch rib cross-section (e.g., during the day, sunlight shines directly on the top or south side of the arch rib, while the bottom or north side is shaded). Specifically, a temperature gradient is generated within the cross-section. The heated areas expand and attempt to lengthen, while the unheated areas remain unchanged. This induces a large additional bending moment within the cross-section, forcing the structure to undergo bending deformation (i.e., deflection or curvature), resulting in significant changes in the arch rib's axis and elevation.

[0040] In some embodiments, when the ambient temperature change (when the temperature change exceeds 5°C) and wind speed level (when the wind speed exceeds level 6), the cable force threshold and elevation threshold calculated in the previous steps are dynamically corrected by a preset environmental impact correction coefficient, wherein the temperature correction coefficient Kt = 1 + α × ΔT (α is the coefficient of linear expansion of the material, and ΔT is the temperature change), and the wind speed correction coefficient Kw = 1 + β × v 2 (β is the wind load influence coefficient, v is the wind speed).

[0041] In a preferred embodiment, the real-time measured values ​​of the cable tension are compared with the dynamically corrected cable tension threshold, and the measured values ​​of the arch rib elevation are compared with the dynamically corrected elevation threshold. When the measured cable tension reaches the lower threshold, the cable adjustment operation is automatically started, controlling two jacks and oil pump tensioning devices on each bank and side of the corresponding cable to perform synchronous, symmetrical, and graded tensioning according to the cable adjustment sequence. During the tensioning process, the cable tension and elevation are monitored in real time. When the measured cable tension reaches the upper threshold or the measured elevation reaches the upper / lower threshold, a stop tensioning command is automatically issued to complete the cable adjustment operation of the current cable segment.

[0042] The threshold calculation and control module compares the initial cable force of 500kN with the lower threshold of 630kN, initiates the cable adjustment operation, and controls two upstream jacks to simultaneously tension the cable in stages, with each stage tensioning by 50kN and holding the load for 2 minutes. Real-time monitoring begins precise control when the cable force reaches 630kN. When the cable force rises to 770kN and the elevation reaches 85.709m, tensioning automatically stops. At this point, the measured axis deviation is X=-0.002m and Y=+0.001m, meeting the requirements.

[0043] After the cable adjustment work for each section is completed, the deviation data between the actual cable force adjustment value, the elevation adjustment value and the target value is stored in the database. The threshold calculation model in step 3 is iteratively optimized by machine learning algorithm (using BP neural network model) to update the values ​​of deviation rate and safety reserve coefficient, so as to improve the accuracy of subsequent section threshold setting.

[0044] The actual cable force deviation was +0.5% and the elevation deviation was +1mm during this adjustment. The data was stored in the database, and the BP neural network model was used to fine-tune the deviation rate to make the subsequent segment threshold calculation more accurate.

[0045] Using the method of this invention, the cable adjustment operations of all sections of the bridge achieved automatic threshold setting and control. When the arch rib was closed, the axial deviation was ≤3mm, the elevation deviation was ≤4mm, and the cable force deviation was ≤2%, all of which were better than the design requirements. Moreover, the construction efficiency was improved by about 30% compared with the traditional method. The structural welds and bolt connections were in good safety condition, which verified the effectiveness and practicality of the invention.

[0046] Example 2 like Figure 2 As shown in the figure, this embodiment of the invention also provides a cable adjustment threshold setting and control system 200 for the hoisting construction of a long-span arch bridge, including: The data acquisition module 201 is used to acquire the construction parameters of the target cable in the hoisting state in real time and to preprocess the data; the construction parameters include: the current hoisting segment number, the initial cable force of the current cable segment, the initial axis coordinates of the arch rib, the initial elevation value, and the construction environment parameters; Communication module 202 is used to obtain the target cable force value, target arch rib axis coordinates, target elevation value and cable adjustment sequence command of the current cable adjustment segment; The cable force threshold calculation module 203 is used to establish a structural mechanics finite element model of the target cable, and calculate the upper and lower thresholds of cable force adjustment based on the construction parameters and the target cable force value according to the structural mechanics finite element model; wherein, a nonlinear force model based on the multi-bundle properties of the cable is introduced into the structural mechanics finite element model. The elevation threshold calculation module 204 is used to calculate the upper and lower thresholds for elevation adjustment based on the geometric alignment control model, according to the target arch rib axis coordinates, target elevation value, previous cumulative deviation and pre-deformation compensation value. The environmental factor calculation module 205 is used to determine the environmental impact correction factor based on the construction environmental parameters, and to dynamically correct the cable force threshold and elevation threshold according to the environmental impact correction factor to obtain the dynamically corrected threshold. Control module 206 is used to compare the real-time monitored cable force and elevation measured values ​​with the dynamically corrected threshold, and generate and execute tension control commands according to the cable adjustment sequence command; The feedback optimization module 207 is used to store the actual adjustment data in the database after each deduction segment adjustment operation is completed, and to iteratively optimize the threshold calculation model through a machine learning model to update the values ​​of each model coefficient.

[0047] The system provided in this embodiment has the following advantages: 1. Automation and Intelligence: It realizes the transformation of the setting of the adjustment threshold from manual experience judgment to automatic calculation. Combined with real-time monitoring data and dynamic correction algorithm, it improves the accuracy and timeliness of threshold setting, reduces human intervention, and enhances the automation level of the adjustment operation.

[0048] 2. High control precision: By constructing a threshold calculation model based on finite element analysis and geometric line control, and introducing environmental impact correction and machine learning feedback optimization mechanisms, the adjustment thresholds of cable force and elevation can dynamically adapt to changes in construction conditions, effectively control error accumulation, and ensure that the installation precision of the arch rib meets the design requirements.

[0049] 3. Enhanced structural safety: The set cable force threshold takes into account the structural safety reserve coefficient, avoiding damage to the cable or arch rib structure caused by over-tensioning; at the same time, the real-time monitoring and automatic stop mechanism can respond to abnormal situations in a timely manner, ensuring structural safety during construction.

[0050] 4. Improved construction efficiency: The rapid generation and execution of automatic control commands shortens the response time of the tracing operation, reduces the time spent on manual monitoring and judgment, and continuously improves the accuracy of threshold setting through feedback optimization, thereby reducing the rework rate and improving the overall construction efficiency.

[0051] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for setting and controlling the adjustment threshold of the chuck in the hoisting construction of a long-span arch bridge, characterized in that, include: Real-time acquisition of construction parameters for the target cable under hoisting conditions, and preprocessing of the data; The construction parameters include: the current hoisting segment number, the initial cable force of the current segment's cable, the initial axis coordinates of the arch rib, the initial elevation value, and construction environment parameters; Obtain the target cable force value, target arch rib axis coordinates, target elevation value, and cable adjustment sequence command for the current cable segment; A structural mechanics finite element model of the target cable is established. Based on the structural mechanics finite element model, the upper and lower threshold values ​​of cable force adjustment are calculated according to the construction parameters and the target cable force value. A nonlinear force model based on the multi-strand properties of the cable is introduced into the structural mechanics finite element model. Based on the geometric alignment control model, the upper and lower threshold values ​​for elevation adjustment are calculated according to the target arch rib axis coordinates, target elevation value, previous cumulative deviation, and pre-deformation compensation value. The environmental impact correction coefficient is determined based on the construction environment parameters, and the cable force threshold and elevation threshold are dynamically corrected according to the environmental impact correction coefficient to obtain the dynamically corrected threshold. The measured values ​​of cable force and elevation monitored in real time are compared with the dynamically corrected thresholds, and tension control commands are generated and executed according to the cable adjustment sequence commands. After each adjustment operation is completed, the actual adjustment data is stored in the database. The threshold calculation model is iteratively optimized through machine learning models, and the values ​​of each model coefficient are updated.

2. The method according to claim 1, characterized in that, The method for constructing the nonlinear force model includes: Obtain the material constitutive parameters and nonlinear influence parameters of the target cable strand; Based on the theory of curvilinear tension friction, nonlinear influence parameters are integrated into the stress-strain relationship of the cable element, and a decay function of cable force along the cable length is established to simulate the non-uniformity of cable force caused by friction in each strand during the tensioning process. A time-varying creep model was introduced to establish the relationship between creep strain, tension holding time, and initial stress, which was used to predict and correct cable force loss in subsequent construction stages. Based on historical data, the initial tension of multiple wire bundles or the uneven initial cable force caused by stress relaxation at the anchorage is quantified within the normal construction error range. Based on the initial non-uniform cable force value, and according to the attenuation function and creep model, the deviation between the final cable force of each strand under nonlinear influence and the theoretical average cable force is calculated under the action of the target cable force, and the nonlinear cable force correction value is obtained.

3. The method according to claim 2, characterized in that, The method for establishing the structural finite element model of the target cable includes: The structural mechanics finite element model serves as the macroscopic framework model of the full-bridge structure. The updated Lagrange method is used to initiate the geometric nonlinear analysis of the arch ribs. Based on the current deformation configuration, the overall structural equilibrium equation is established to ensure accurate tracking of structural stiffness changes under long-span cantilever conditions. The arch rib section characteristics, cable material properties, and temporary tower information corresponding to the current hoisting segment number are used as the geometric and material input parameters of the finite element model, and the initial value of the cable force is used as the initial state input data. The nonlinear force model is embedded in the finite element framework as a nonlinear constitutive model of the cable element, in order to replace the simple linear material properties of the cable element.

4. The method according to claim 2, characterized in that, The calculation methods for the upper and lower thresholds of the cable tension adjustment include: in, Indicates the upper limit threshold of cable force. This indicates the lower limit threshold of cable tension. Indicates the target cable force value. This indicates the allowable cable tension deviation rate during construction monitoring. Indicates the structural safety reserve factor. This represents the force distribution correction term caused by uneven stress relaxation when the i-th strand reaches the target force. This indicates the number of strands in the cable.

5. The method according to claim 1, characterized in that, The geometric alignment control model includes a cumulative deviation tracking unit, a dynamic sensitivity calculation unit, and an elevation calculation unit; The cumulative deviation tracking unit is used to calculate and store the cumulative elevation deviation and cumulative axis deviation between the actual adjustment deviation and the target deviation of all previous segments based on the initial axis coordinates of the arch rib, the initial elevation value, the target arch rib axis coordinates and the target elevation value. The dynamic sensitivity calculation unit is used to calculate the dynamic geometric sensitivity coefficient of the arch rib and to calculate the influence rate of the slight change in cable force on the elevation based on the current stiffness of the cantilever. The elevation calculation unit is used to superimpose the static displacement compensation and the dynamic safety tolerance onto the target elevation value to obtain the final elevation adjustment threshold.

6. The method according to claim 5, characterized in that, The upper and lower thresholds for calculating elevation adjustment include: in, This indicates the upper limit threshold for elevation adjustment. This indicates the lower limit threshold for elevation adjustment. Indicates the target elevation value. Indicates the pre-deformation compensation value. Indicates the allowable design deviation. Indicates the cumulative elevation deviation of the preceding sequence. This represents the dynamic geometric sensitivity coefficient of the arch rib. This indicates the dynamic safety tolerance of the cable force.

7. The method according to claim 1, characterized in that, The determination of environmental impact correction coefficients based on construction environment parameters includes: in, This represents the overall correction factor. This represents the uniform temperature correction factor. , This represents the coefficient of linear expansion of the material. This indicates the change in average ambient temperature. This represents the temperature gradient correction factor. This represents the wind speed correction factor. β represents the wind load influence coefficient. Indicates real-time wind speed. This represents the creep correction factor, used to correct for the decrease in cable force over time caused by the stress creep effect of the cable material.

8. The method according to claim 1, characterized in that, Based on the cable adjustment sequence instruction, tension control instructions are generated and executed, including: The PID control algorithm is used to dynamically calculate the tension adjustment amount based on the real-time cable force deviation, and the drive parameters of the jack oil pump system are adjusted accordingly. The calculation formula for the PID control algorithm is as follows: in, To dynamically adjust the increment of the output tension force, This represents the cable force deviation, which is the difference between the dynamically corrected cable force threshold at the current moment and the real-time monitored measured cable force value. , , These are the preset proportional coefficient, integral coefficient, and differential coefficient, respectively.

9. The method according to claim 1, characterized in that, The machine learning model is a BP neural network, and it outputs the effective value correction of the elastic modulus of the cable in real time based on multi-dimensional input features, so as to dynamically update the cable force threshold calculation model. The multidimensional input features include at least: cable force deviation rate, elevation deviation, tensioning step length, ambient temperature, and historical extension.

10. A threshold setting and control system for cable adjustment in the hoisting construction of a long-span arch bridge, characterized in that, include: The data acquisition module is used to acquire construction parameters of the target cable in the hoisting state in real time and to preprocess the data. The construction parameters include: the current hoisting segment number, the initial cable force of the current segment's cable, the initial axis coordinates of the arch rib, the initial elevation value, and construction environment parameters; The communication module is used to obtain the target cable force value, target arch rib axis coordinates, target elevation value, and cable adjustment sequence command for the current cable segment. The cable force threshold calculation module is used to establish a structural mechanics finite element model of the target cable, and calculate the upper and lower thresholds of cable force adjustment based on the construction parameters and the target cable force value according to the structural mechanics finite element model; wherein, a nonlinear force model based on the multi-bundle properties of the cable is introduced into the structural mechanics finite element model; The elevation threshold calculation module is used to calculate the upper and lower thresholds for elevation adjustment based on the geometric alignment control model, according to the target arch rib axis coordinates, target elevation value, previous cumulative deviation, and pre-deformation compensation value. The environmental factor calculation module is used to determine the environmental impact correction factor based on the construction environmental parameters, and to dynamically correct the cable force threshold and elevation threshold according to the environmental impact correction factor to obtain the dynamically corrected threshold. The control module is used to compare the real-time monitored cable force and elevation measured values ​​with the dynamically corrected threshold, and generate and execute tension control commands according to the cable adjustment sequence command; The feedback optimization module is used to store the actual adjustment data in the database after each deduction segment adjustment operation is completed, and to iteratively optimize the threshold calculation model through a machine learning model to update the values ​​of each model coefficient.

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