Carbon fiber cloth prestress tension shield segment reinforcing method

Abstract

The invention discloses a carbon fiber cloth prestress tension shield segment reinforcing method, and relates to the technical field of shield tunnel engineering. The method comprises the following steps: establishing a mechanical model, collecting the actual structure size, material attribute and damage condition data of the shield segment, establishing a three-dimensional solid model according to the collected data by adopting ANSYS finite element software, and establishing a three-dimensional model by considering the geometrical shape, boundary condition and load distribution of the segment and the mechanical property of a reinforcing material. A prestress tensioning effect is introduced into the model, the influence of the carbon fiber cloth on the structural stress of the duct piece under different prestress levels such as 50%, 75% and 100% design prestress is analyzed, and the optimal prestress application range and mode are determined through simulation calculation. According to the carbon fiber cloth prestress tensioning shield segment reinforcing method, through scientific model supporting and detailed data analysis, the prediction and control capacity of the reinforcing effect is improved, and the stability and durability of the shield segment are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of shield tunnel engineering, and in particular relates to a method for reinforcing a shield segment by prestressing it with carbon fiber cloth. Background Art

[0002] With the widespread application and in-depth development of shield tunnel engineering technology around the world, the stability and durability of shield segments, as the core component of tunnel structure, are directly related to the safety and life of the entire tunnel project. However, in actual projects, shield segments often face challenges from various complex stresses and environmental factors, making reinforcement issues particularly important.

[0003] However, traditional reinforcement methods have many shortcomings in this field, mainly reflected in the lack of scientific model support and detailed data analysis, which greatly limits the ability to predict and control the reinforcement effect. First of all, from the perspective of model support, traditional reinforcement methods often rely on empirical formulas, engineering analogies or simple mechanical calculations, lacking comprehensive consideration and detailed analysis of factors such as specific engineering conditions, geological environment, segment material properties and construction technology. This reinforcement design based on empiricism is difficult to accurately reflect the complex behavior of shield segments under actual stress conditions, such as stress redistribution, crack expansion, material aging and other processes, which leads to the reinforcement plan often having a certain degree of blindness and uncertainty. In addition, as shield tunnel projects move towards larger spans and deeper burial depths, , and more complex geological conditions, the limitations of traditional models have become increasingly prominent, making it difficult to adapt to the reinforcement needs under the new situation. Secondly, from the perspective of data analysis, traditional reinforcement methods often lack a systematic and comprehensive data collection and analysis system during implementation. On the one hand, the monitoring methods are relatively backward and cannot achieve real-time and accurate monitoring of key parameters such as shield segment stress, deformation, and cracks; on the other hand, even if relevant data are obtained, it is often difficult to effectively process and analyze them due to problems such as large data volume, diverse types, and uneven quality. This lack of data or insufficient analysis makes it difficult to evaluate the reinforcement effect, and it is difficult to promptly discover and correct possible problems in the reinforcement process, let alone provide strong support for the subsequent optimization of reinforcement plans. Summary of the invention

[0004] The purpose of the present invention is to improve the prediction and control capabilities of the reinforcement effect through scientific model support and detailed data analysis, and to ensure the stability and durability of the shield segments, and to propose a carbon fiber cloth prestressed tensioned shield segment reinforcement method.

[0005] In order to achieve the purpose of the present invention, the present invention discloses a method for reinforcing a shield segment using prestressed carbon fiber cloth, comprising the following steps:

[0006] S10. Establish a mechanical model; collect the actual structural dimensions, material properties and damage data of the shield segments, use ANSYS finite element software, establish a three-dimensional solid model based on the collected data, consider the geometric shape, boundary conditions, load distribution and mechanical properties of the reinforcement materials of the segments, introduce the prestressing effect into the model, analyze the influence of carbon fiber cloth on the segment structural stress at different prestress levels, and determine the optimal prestressing range and method through simulation calculation;

[0007] S20. Determine key parameters. Based on the results of mechanical model analysis, determine the key parameters that affect the reinforcement effect, including the thickness, number of layers, prestress, tensioning speed, tensioning sequence of the carbon fiber cloth, and the type and performance of the adhesive. Optimize these parameters through a combination of experimental verification and numerical simulation to ensure the best reinforcement effect.

[0008] S30, data collection and analysis: During the reinforcement process, various key data are collected and recorded in real time, including the real-time change of tension force, the strain distribution of carbon fiber cloth, and the stress response of the tube segment structure; strain gauges, fiber grating sensors, stress gauges or strain gauges are used to measure the strain distribution of carbon fiber cloth and the stress change of the tube segment structure, respectively, and the collected data are analyzed in detail to verify the accuracy of the mechanical model and the rationality of the parameter setting; according to the analysis results, the reinforcement plan is adjusted in a timely manner;

[0009] S40. Implement reinforcement. According to the optimized parameters and model guidance, implement carbon fiber cloth prestressed tension reinforcement. During the reinforcement process, strictly control various operating parameters to ensure that the reinforcement effect meets expectations. After the reinforcement is completed, conduct a comprehensive evaluation of the reinforcement effect, including tests on structural strength, stiffness, stability and durability, to ensure that the reinforcement effect meets the design requirements.

[0010] Furthermore, step S10 specifically includes the following steps:

[0011] S101. Data collection and collation: On-site measurements or review of design documents to collect the actual structural dimensions of the shield segments, including the segment diameter, thickness, ring width, location and size of the longitudinal and ring seams, obtain the segment material property data, and the yield strength, diameter, and spacing of the steel bars, and evaluate and record the damage of the segments, including the location, length, width, depth, and possible damage types of the cracks;

[0012] S102, finite element software selection and setting; select ANSYS as the finite element analysis software, start the specific module or toolbox in the ANSYS finite element analysis software that is suitable for the current analysis needs, set the analysis type, and select static analysis or nonlinear analysis to consider the nonlinearity of the material and the geometric nonlinearity of the structure;

[0013] S103, 3D solid model construction: based on the collected structural dimension data, draw the 3D geometric model of the segment in ANSYS, use the modeling tools provided by ANSYS, or import the CAD model for conversion, define the material properties, input the collected concrete and steel bar material properties into the material library of ANSYS, and assign them to the corresponding parts in the model, divide the mesh, and divide the model with appropriate mesh type and size to ensure calculation accuracy and efficiency;

[0014] S104, boundary conditions and load application: according to the actual working conditions of the segment, boundary conditions such as fixed constraints and sliding constraints are set to simulate the actual stress conditions of the segment in the tunnel, and loads are applied, including hydrostatic pressure, earth pressure, and construction loads, to ensure that the load distribution is consistent with the actual situation;

[0015] S105, prestressed tensioning effect simulation: introduce carbon fiber cloth reinforcement layer into the model, define the material properties and cross-sectional characteristics of carbon fiber cloth, set prestressed tensioning simulation, and simulate the tensioning effect of carbon fiber cloth under different prestressing levels by applying temperature load, displacement load or special prestressed unit method;

[0016] S106, Analysis and Optimization: Run simulation calculations to analyze the stress distribution and deformation of the segment structure under different prestressing levels and evaluate the reinforcement effect; compare the stress state before and after reinforcement to determine the optimal prestressing range and method; adjust the model parameters or reinforcement scheme according to the analysis results and perform iterative optimization until a satisfactory reinforcement effect is achieved;

[0017] S107. Result verification and output: verify the rationality and accuracy of the simulation results, compare them with experimental data or actual observation results, and output the simulation results, including stress cloud map, displacement cloud map, and prestress distribution map, to provide a scientific basis for subsequent reinforcement construction.

[0018] Furthermore, in step S103, after the three-dimensional solid model is constructed, the accuracy of the model will be tested using known or verifiable working conditions, the predictive ability of the model will be verified using known experimental data or previous analysis results, and adjustments or calibrations will be made as needed to ensure that the model can accurately reflect the actual physical behavior. In step S107, the uncertainties and potential risks in the simulation results will be evaluated, and the impact of these uncertainties and risks on the reinforcement effect will be quantified. By considering the changes in material properties, the uncertainty of loads, and the limitations of model assumptions, a more robust reinforcement plan can be formulated to provide support for decision-making during the construction process.

[0019] Furthermore, step S20 specifically includes the following steps:

[0020] S201, based on the preliminary results of the finite element analysis in step S10, identify key parameters that have a significant impact on the reinforcement effect, including the thickness, number of layers, prestressing size, tensioning speed, tensioning sequence of the carbon fiber cloth, and the type and performance of the adhesive, and select one or more initial values ​​or ranges for each parameter for further research based on experience and preliminary analysis;

[0021] S202. Design a detailed experimental plan for each key parameter;

[0022] S203. Conduct experiments one by one according to the experimental design. During the experiments, the experimental conditions need to be strictly controlled to ensure the accuracy and repeatability of the experimental results, and key data during the experiments, such as stress changes, deformation conditions, and failure modes, should be recorded;

[0023] S204, using finite element analysis software ANSYS, establishing a corresponding numerical model according to the experimental conditions, performing numerical simulation, comparing the numerical simulation results with the experimental results, verifying the accuracy and reliability of the model, and if there are differences, analyzing the reasons and adjusting the model;

[0024] S205. Based on the results of experiments and numerical simulations, key parameters are optimized, the influence of different parameters on the reinforcement effect is analyzed, and the best parameter combination is determined. Multiple iterations are required to continuously adjust parameter values ​​and repeat the experiments and numerical simulation processes until the optimal reinforcement solution is found.

[0025] Furthermore, when conducting numerical simulations, it is also necessary to ensure the accuracy of the input data, verify the numerical simulation results, and compare them with the experimental data to ensure consistency between the two. When optimizing key parameters, in addition to considering the impact of a single parameter on the reinforcement effect, analyze the interaction between multiple parameters, and study the comprehensive impact of different parameter combinations on the reinforcement effect by designing multi-factor experiments or using statistical methods such as variance analysis and regression analysis.

[0026] Furthermore, step S30 specifically includes the following steps:

[0027] S301. Equipment preparation and installation: Select and prepare strain gauges, fiber grating sensors, stress gauges or strain gauges, and ensure that these devices have been calibrated to meet the measurement accuracy requirements. On the reinforced segment structure, install and fix the measurement equipment according to the predetermined measurement point arrangement plan to ensure that the equipment is installed in an accurate position and can accurately reflect the strain distribution of the carbon fiber cloth and the stress changes of the segment structure.

[0028] S302, data acquisition system startup, build and start the data acquisition system, connect the measuring equipment to the data acquisition device, set the data acquisition parameters, and ensure that data can be collected in real time and accurately;

[0029] S303, real-time data collection, during the reinforcement process, start the data acquisition system to collect and record various key data in real time, including real-time changes in tension, strain distribution of carbon fiber cloth, and stress response of segment structure, to ensure the integrity and accuracy of data records, and regularly check the operating status of the data acquisition system to prevent data loss or errors;

[0030] S304, data preprocessing, preprocessing the collected data, including data cleaning to remove outliers and noise, data calibration and comparison with standard values, and data filtering to remove high-frequency noise, so as to improve the accuracy and reliability of data analysis;

[0031] S305, data analysis, using statistical analysis, signal processing, image recognition methods, to conduct detailed analysis on the pre-processed data, analyze the strain distribution law of the carbon fiber cloth, including the size, direction, and change trend of the strain, analyze the stress response characteristics of the segment structure, including the distribution, size, and change trend of the stress, and whether there is stress concentration or abnormal stress phenomenon, compare the analysis results with the prediction results of the mechanical model, and verify the accuracy of the mechanical model and the rationality of the parameter setting;

[0032] S306. Evaluation and adjustment of reinforcement scheme: Based on the data analysis results, the current reinforcement scheme is evaluated to assess whether the reinforcement effect has achieved the expected goal and whether there are areas that need improvement. If the reinforcement effect is not ideal or there are areas that need improvement, the reinforcement scheme is adjusted in a timely manner based on the data analysis results and the prediction results of the mechanical model. The adjustments may include the thickness of the carbon fiber cloth, the number of layers, the size of the prestress, the tensioning speed, and the tensioning sequence. After adjusting the reinforcement scheme, re-analyze the data to verify whether the adjusted effect meets expectations.

[0033] Furthermore, after data cleaning, calibration and filtering, data verification is performed to ensure that the preprocessed data conforms to the actual situation and expected goals. For abnormal data found during the preprocessing process, an exception handling process should be formulated, including anomaly identification, cause analysis and handling measures.

[0034] Furthermore, step S40 specifically includes the following steps:

[0035] S401. According to the optimized reinforcement plan, prepare the required carbon fiber cloth, prestressed tensioning equipment, adhesives, and supporting materials, and ensure that the quality of all materials meets the standards. Check whether the prestressed tensioning equipment and measuring instruments are intact to ensure that they can operate normally and accurately measure during the construction process. Set up safety warning signs at the reinforcement site to ensure the safe isolation of the construction area, and prepare the scaffolding and lighting equipment required for construction;

[0036] S402. Clean the surface of the reinforced segment structure to remove dirt, oil stains, and rust to ensure that the surface is clean and flat. If necessary, perform surface repair to improve the bonding between the carbon fiber cloth and the structure. Apply a layer of special bonding primer, usually epoxy resin adhesive, on the surface of the structure to improve the bonding effect between the carbon fiber cloth and the surface of the structure. Note that the primer should be applied evenly and without omissions. According to the design plan, cut the carbon fiber cloth into a suitable size and shape and install it to the predetermined position to ensure that the carbon fiber cloth fits tightly to the surface of the structure without wrinkles or bubbles. Install the prestressing equipment and adjust it. To the appropriate tension, according to the optimized parameter model, set the tensioning speed and tensioning force to ensure that the tensioning process is smooth and controllable, start the tensioning equipment, and prestress the carbon fiber cloth. During the tensioning process, strictly control various operating parameters such as tensioning speed and tensioning force to ensure that the tensioning effect meets the design requirements. At the same time, pay attention to observe the strain distribution of the carbon fiber cloth and the stress response of the segment structure, and adjust the tensioning strategy in time. After the carbon fiber cloth is tensioned, wait for it to be fully cured according to the curing requirements of the adhesive. During the curing period, pay attention to keeping the temperature and humidity conditions of the construction environment stable to ensure the curing effect;

[0037] S403. After the reinforcement is completed, first conduct an appearance inspection to check whether the carbon fiber cloth is flat, wrinkle-free, and bubble-free. At the same time, check whether the tensioning equipment has been removed and the construction area is tidy. Conduct a comprehensive assessment of the reinforced structure, including tests on structural strength, stiffness, stability, and durability. The test method can be selected according to the design requirements and relevant standards, such as using a tensile tester to test the structural strength and using a vibration tester to test the structural stiffness. Compare and analyze the test results with the design requirements to assess whether the reinforcement effect meets the requirements. If any non-compliance is found, find the cause in a timely manner and take appropriate remedial measures. Organize the various data, test results, and evaluation conclusions during the reinforcement process into a report for subsequent reference and archiving. The report should include the reinforcement plan, construction steps, test methods, test results, and evaluation conclusions.

[0038] Compared with the prior art, the significant progress of the present invention is that: in step S10, by establishing a detailed mechanical model and using ANSYS finite element software to perform three-dimensional solid simulation, this method not only takes into account complex factors such as the geometric shape, boundary conditions, and load distribution of the pipe segment, but also introduces the prestressing tensioning effect, and deeply analyzes the influence of carbon fiber cloth on the stress of the pipe segment structure under different prestressing levels. This method based on a scientific model can accurately predict the reinforcement effect, avoid the blindness and uncertainty in traditional reinforcement methods, and provide strong theoretical support for reinforcement design. At the same time, the optimal prestressing application range and method are determined by simulation calculation, which further improves the controllability and predictability of the reinforcement effect. In step S20, based on the analysis results of the mechanical model, the key parameters affecting the reinforcement effect are clarified, and these parameters are optimized by combining experimental verification and numerical simulation. This step not only covers the thickness, number of layers, prestressing size, tensioning speed, tensioning sequence, and types and properties of adhesives of carbon fiber cloth, but also ensures the accuracy and rationality of reinforcement parameters through meticulous experimental design and data analysis. This systematic parameter optimization process greatly improves the reinforcement. The scientificity and effectiveness of the reinforcement scheme overcomes the problem of inaccurate parameter setting in traditional reinforcement methods. In the data collection and analysis link in step S30, by collecting and recording various key data in the reinforcement process in real time and using advanced measuring equipment to conduct detailed analysis of the data, it not only verifies the accuracy of the mechanical model and the rationality of the parameter setting, but also provides data support for timely adjustment of the reinforcement scheme. This data-based decision-making process makes the reinforcement process more transparent and controllable, and can promptly discover and correct potential problems, ensuring the stability and reliability of the reinforcement effect. Finally, in step S40, Reinforcement was implemented according to the optimized parameters and model guidance, and various operating parameters were strictly controlled to ensure that the reinforcement effect met expectations. The comprehensive evaluation after the reinforcement was completed not only verified whether the reinforcement effect met the design requirements, but also provided valuable experience and reference for subsequent tunnel projects. This closed-loop reinforcement process not only improved the efficiency and quality of reinforcement work, but also promoted the development and progress of shield tunnel engineering technology. In summary, through scientific model support and detailed data analysis, many defects in traditional reinforcement methods were overcome, providing an efficient, reliable and controllable solution for the reinforcement of shield segments.

[0039] In order to more clearly illustrate the functional characteristics and structural parameters of the present invention, further description is given below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 The present invention is a flowchart of the method for reinforcing a shield segment using prestressed carbon fiber cloth. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] Combination Figure 1 As shown, the carbon fiber cloth prestressed tensioning shield segment reinforcement method of the present invention comprises the following steps:

[0044] S10. Establish a mechanical model, collect the actual structural dimensions, material properties and damage data of the shield segments, use ANSYS finite element software, establish a three-dimensional solid model based on the collected data, consider the geometric shape, boundary conditions, load distribution and mechanical properties of the reinforcement materials of the segments, introduce the prestressing effect into the model, analyze the influence of carbon fiber cloth on the structural stress of the segments under different prestress levels such as 50%, 75%, and 100% of the design prestress, and determine the optimal prestressing range and method through simulation calculation;

[0045] Step S10 specifically includes the following steps:

[0046] S101. Data collection and collation, field measurement or review of design documents, collect the actual structural dimensions of the shield segments, including the segment diameter, thickness, ring width, location and size of the longitudinal and ring seams, etc., obtain the segment material property data, such as the compressive strength, tensile strength, elastic modulus of concrete, etc., and the yield strength, diameter, spacing, etc. of the steel bars, evaluate and record the damage of the segments, including the location, length, width, depth of the cracks, and possible damage types such as spalling, corrosion, etc.;

[0047] S102, Finite element software selection and setting, select ANSYS as the finite element analysis software, and start the corresponding module such as Structural Mechanics module, set the analysis type, usually static analysis or nonlinear analysis, to consider the nonlinearity of the material and the geometric nonlinearity of the structure;

[0048] Specifically, the "starting the corresponding module" mentioned in step S102 refers to starting a specific module or toolbox in the ANSYS finite element analysis software that is suitable for the current analysis needs. As a powerful finite element analysis software, ANSYS contains multiple modules for dealing with different types of physical and engineering problems, such as structural analysis, thermal analysis, fluid dynamics analysis, electromagnetic analysis, etc. For the establishment of the mechanical model of the carbon fiber cloth prestressed tensioning shield segment reinforcement method, the main focus is on the structural analysis module. In ANSYS, this usually involves starting the "Structural" or "Mechanical" module, which is specifically used to deal with mechanical analysis problems related to the structure, including static analysis, dynamic analysis, nonlinear analysis, etc. Therefore, the "starting the corresponding module" mentioned in step S102 refers to starting the structural analysis or mechanical analysis module in ANSYS to carry out subsequent modeling, material property setting, meshing, boundary conditions and load application, and prestressed tensioning effect simulation. These modules provide a wealth of tools and options for accurately simulating and analyzing the mechanical behavior of shield segments during the reinforcement process.

[0049] S103. 3D solid model construction. Based on the collected structural dimension data, the 3D geometric model of the segment is drawn in ANSYS. The modeling tools provided by ANSYS, such as DesignModeler, can be used, or the CAD model can be imported for conversion. The material properties are defined. The collected material properties of concrete and steel bars are input into the material library of ANSYS and assigned to the corresponding parts in the model. The mesh is divided and the model is divided using the appropriate mesh type and size to ensure the calculation accuracy and efficiency.

[0050] Specifically, "using the appropriate mesh type" means selecting a mesh type that can balance calculation accuracy and efficiency based on factors such as the geometry of the shield segment, material properties, stress conditions, and analysis purpose. The following is a detailed explanation and discussion of the "appropriate" mesh type:

[0051] (1) Principles for selecting grid types

[0052] Geometry adaptability: The mesh type should be able to adapt to the complex geometry of the shield segment to ensure that the meshed model can accurately reflect the characteristics of the actual structure. For example, for segments with curved surfaces or irregular shapes, a mesh type that can flexibly adapt to these shapes should be selected.

[0053] Material property matching: The mesh type should match the properties of the shield segments and carbon fiber reinforcement materials. Different materials may have different sensitivities to mesh types, so a mesh type that accurately reflects the mechanical properties of the material should be selected.

[0054] Consideration of stress conditions: The mesh type should be able to accurately simulate the deformation and stress distribution of the shield segment during stress. For areas with complex stress or concentrated stress, a mesh type with higher calculation accuracy should be selected.

[0055] Balance between computational efficiency and accuracy: Under the premise of satisfying computational accuracy, a grid type with higher computational efficiency should be selected as much as possible to shorten the analysis cycle and reduce computational costs.

[0056] (2) Common grid types and their characteristics

[0057] Tetrahedral mesh: It is small in size, large in number, and suitable for meshing of complex geometric surfaces. It can be automatically generated at a fast speed. It is used in scenarios where complex geometry or fast meshing is required. In some complex areas or curved parts of shield segments, tetrahedral mesh may be a suitable choice.

[0058] Hexahedral mesh: The characteristic is that the number is relatively small, but at the same size, the hexahedral mesh can greatly reduce the number of cells in the mesh. It is suitable for the division of regular geometric shapes. When the geometry of the shield segment is relatively regular, the hexahedral mesh may be a better choice. It can provide higher calculation accuracy and help reduce the amount of calculation.

[0059] Prismatic and Pyramidal Meshes: Prismatic meshes are suitable for geometries with prismatic features. Pyramidal meshes are often used to create a transition area between hexahedral and tetrahedral meshes. These mesh types may be valuable in certain areas of shield segments, such as transition sections or connection parts.

[0060] (3) Recommendations for selecting mesh types

[0061] For complex geometric shapes, tetrahedral meshes or hybrid meshes (a combination of tetrahedrons and hexahedrons) are preferred to ensure that the mesh can adapt to complex shapes and accurately reflect structural features. For regular geometric shapes, hexahedral meshes are preferred to improve calculation accuracy and reduce calculation workload. For transition areas, prismatic meshes or pyramidal meshes are considered for transition to ensure mesh continuity and calculation accuracy.

[0062] Comprehensively consider computational efficiency and accuracy: When selecting a mesh type, you should comprehensively consider the requirements for computational efficiency and accuracy. On the premise of satisfying computational accuracy, try to choose a mesh type with higher computational efficiency.

[0063] In summary, the "appropriate" mesh type should be selected according to the actual situation of the shield segment and the analysis requirements. By comprehensively considering factors such as geometry, material properties, stress conditions, and calculation efficiency and accuracy, the most suitable mesh type can be selected, thus providing an accurate and reliable model basis for subsequent finite element analysis.

[0064] S104, boundary conditions and load application, according to the actual working conditions of the segment, boundary conditions such as fixed constraints and sliding constraints are set to simulate the actual stress conditions of the segment in the tunnel, and loads are applied, including hydrostatic pressure, earth pressure, construction load, etc., to ensure that the load distribution is consistent with the actual situation;

[0065] S105, prestressed tensioning effect simulation, introduce carbon fiber cloth reinforcement layer into the model, define the material properties and cross-sectional characteristics of carbon fiber cloth, set prestressed tensioning simulation, and simulate the tensioning effect of carbon fiber cloth under different prestressing levels such as 50%, 75%, and 100% design prestressing by applying temperature load, displacement load or special prestressing unit;

[0066] S106. Analysis and optimization, run simulation calculations, analyze the stress distribution and deformation of the segment structure under different prestressing levels, evaluate the reinforcement effect, compare the stress state before and after reinforcement, determine the best prestressing application range and method, adjust the model parameters or reinforcement scheme according to the analysis results, and perform iterative optimization until a satisfactory reinforcement effect is achieved;

[0067] S107. Result verification and output. Verify the rationality and accuracy of the simulation results. Compare them with experimental data or actual observation results. Output simulation results, including stress cloud map, displacement cloud map, prestress distribution map, etc., to provide a scientific basis for subsequent reinforcement construction.

[0068] By combining field measurement with design document review, the actual structural dimensions, material properties and damage conditions of the shield segments are accurately collected, laying a solid foundation for subsequent modeling and analysis. In the finite element analysis, not only the nonlinearity of the material and the geometric nonlinearity of the structure are considered, but also the geometric shape, boundary conditions and load distribution of the segments are fully simulated through the construction of a three-dimensional solid model, making the simulation results closer to the actual situation. By introducing a carbon fiber cloth reinforcement layer and setting up a prestressed tensioning simulation, the reinforcement effect of the carbon fiber cloth on the segment structure under different prestress levels can be accurately simulated, providing a scientific basis for determining the optimal range and method of prestressing. Through the analysis and optimization steps, the model parameters or reinforcement schemes are continuously adjusted, and iterative optimization is performed to ensure the optimization of the reinforcement effect. At the same time, through result verification and output, the rationality and accuracy of the simulation results are further ensured, providing a reliable basis for subsequent reinforcement construction.

[0069] In a subway shield tunnel project in a certain city, a section of shield segment with cracks and slight corrosion was reinforced. The specific operations were as follows: Data collection and collation: First, through field measurements and reference to design documents, the diameter, thickness, ring width, specific location and size of the longitudinal and ring seams of the segment were collected. At the same time, the material property data such as the compressive strength, tensile strength, and elastic modulus of the concrete, as well as the yield strength, diameter, spacing and other information of the steel bars were obtained. In addition, the crack location, length, width, depth, and damage such as spalling and corrosion on the segment were evaluated and recorded in detail. Finite element software selection and setting: ANSYS was selected as the finite element analysis software, and the Structural In the Mechanics module, according to the analysis requirements, the static analysis type is set to consider the nonlinearity of the material and the geometric nonlinearity of the structure. The three-dimensional solid model is constructed: Based on the collected structural size data, the DesignModeler tool is used in ANSYS to draw the three-dimensional geometric model of the segment. Then, the material properties of concrete and steel bars are input into the material library of ANSYS and assigned to the corresponding parts in the model. The model is divided using appropriate grid types and sizes to ensure calculation accuracy and efficiency. Boundary conditions and load application: According to the actual working conditions of the segment, boundary conditions such as fixed constraints and sliding constraints are set to simulate the actual stress conditions of the segment in the tunnel. At the same time, hydrostatic pressure, earth pressure, construction load and other loads are applied to ensure that the load distribution is consistent with the actual situation. Prestressed tension effect simulation: Carbon fiber is introduced into the model. The carbon fiber cloth reinforcement layer is defined, and the material properties and cross-sectional characteristics of the carbon fiber cloth are defined. By setting the prestressed tensioning simulation, the tensioning effect of the carbon fiber cloth at the design prestressing levels of 50%, 75%, and 100% is simulated respectively. Analysis and optimization: After running the simulation calculation, the stress distribution and deformation of the segment structure under different prestressing levels are analyzed. By comparing the stress state before and after reinforcement, the optimal prestressing application range is determined to be 40% of the design bearing capacity of the segment, and the model parameters and reinforcement scheme are adjusted accordingly. After many iterative optimizations, a satisfactory reinforcement effect is finally achieved. Result verification and output: The simulation results are compared and verified with the experimental data, and it is found that the two have a high degree of consistency, which verifies the rationality and accuracy of the simulation results. Finally, the simulation results including stress cloud map, displacement cloud map, prestress distribution map, etc. are output, which provides a scientific basis for subsequent reinforcement construction.

[0070] In step S103, after the three-dimensional solid model is constructed, the accuracy of the model should be tested using known or verifiable working conditions. The predictive ability of the model can be verified using known experimental data or previous analysis results, and adjustments or calibrations should be made as needed to ensure that the model can accurately reflect the actual physical behavior. In step S107, the uncertainty and potential risks in the simulation results should be evaluated, and the impact of these uncertainties and risks on the reinforcement effect should be quantified. By considering factors such as changes in material properties, uncertainty in loads, and limitations of model assumptions, a more robust reinforcement plan can be developed and support can be provided for decision-making during the construction process.

[0071] In step S103, by introducing the use of known or verifiable working conditions to test the accuracy of the three-dimensional solid model, this measure significantly enhances the reliability and predictive ability of the model. Specifically, by using known experimental data or previous analysis results to verify the model, deviations in the model can be discovered and corrected in a timely manner to ensure that the model can accurately reflect the actual physical behavior after it is built. This verification process not only improves the accuracy of the model, but also enhances the applicability of the model under complex working conditions, providing a solid foundation for subsequent analysis. Furthermore, in step S107, by evaluating the uncertainty and potential risks in the simulation results and quantifying the impact of these uncertainties and risks on the reinforcement effect, a scientific basis is provided for formulating a more robust reinforcement plan. In actual engineering, factors such as changes in material properties, uncertainty in loads, and limitations of model assumptions often have a significant impact on the reinforcement effect. By comprehensively considering these factors and quantifying their impact on the simulation results, the feasibility and risk level of the reinforcement plan can be more accurately evaluated, which helps engineers make more informed decisions when formulating reinforcement plans, and also provides strong support for risk management and response measures during construction.

[0072] Specifically, in one embodiment, it is assumed that a shield segment in a subway tunnel located under complex geological conditions is being reinforced. The tunnel passes through a variety of soil layers, including soft soil, hard soil and rock layers, and there are important buildings above the tunnel. Therefore, the reinforcement work needs to consider not only the strength of the segment itself, but also the geological conditions, load changes and various uncertain factors in the construction process. The detailed implementation steps of step S107 are as follows:

[0073] (1) Evaluate the uncertainty and potential risks in simulation results

[0074] Uncertainty of material properties: Considering that the material properties of concrete and steel bars may be affected by various factors such as temperature, humidity, and age, the fluctuation range of material properties is introduced in the simulation. For example, it is assumed that the compressive strength of concrete has a fluctuation range of ±10% based on the standard value, and the yield strength of steel bars has a fluctuation range of ±5%.

[0075] Uncertainty of loads: Since there are buildings above the tunnel and the buildings may be affected by various external loads such as wind load and snow load, the uncertainty of these loads is taken into account in the simulation. For example, it is assumed that the hydrostatic pressure and earth pressure have a fluctuation range of ±15% based on the standard value, and the construction load has a fluctuation range of ±10%.

[0076] Limitations of model assumptions: In the simulation, some simplifying assumptions may be made, such as ignoring the interaction between the tunnel and the surrounding soil, assuming that the segments are completely rigidly connected, etc. These assumptions may lead to certain deviations between the simulation results and the actual situation.

[0077] (2) Quantifying the impact of uncertainty and risk on reinforcement effectiveness

[0078] Through sensitivity analysis, it was determined which parameters had the greatest impact on the reinforcement effect. For example, it was found that fluctuations in the concrete compressive strength had the most significant impact on the reinforcement effect.

[0079] Next, a probability analysis was conducted to calculate the probability distribution of the reinforcement effect under different parameter combinations. For example, the probability of failure of the reinforced segment was calculated when multiple parameters such as concrete compressive strength, steel yield strength, and load fluctuated simultaneously.

[0080] (3) Develop a more robust reinforcement plan

[0081] Based on the above analysis, the reinforcement plan was adjusted. For example, the number of carbon fiber cloth layers was increased to improve the overall strength of the segment. At the same time, monitoring and testing were strengthened during the construction process to ensure that the reinforcement effect met expectations.

[0082] An emergency plan has also been developed to deal with possible emergencies. For example, if any abnormality is found in the pipe segment during the reinforcement process, construction will be stopped immediately and inspection and treatment will be carried out.

[0083] (4) Provide support for decision-making during the construction process

[0084] During the construction process, the construction parameters and reinforcement schemes were adjusted in a timely manner based on the comparison between the simulation results and the actual situation. For example, if it was found that the actual load exceeded the expected value in the simulation, the prestressing level of the carbon fiber cloth was immediately increased.

[0085] Real-time monitoring and data analysis also provide a scientific basis for decision-making during the construction process. For example, by monitoring the strain distribution of carbon fiber cloth and the stress changes of the segment structure, potential safety hazards can be discovered and dealt with in a timely manner.

[0086] Through the detailed implementation of the above step S107, the uncertainty and potential risks in the simulation results were successfully evaluated, and a more robust reinforcement plan was formulated. This not only improves the reliability and safety of the reinforcement effect, but also provides a scientific basis for decision-making during the construction process. This example fully demonstrates the importance and practicality of step S107 in the dependent claims.

[0087] S20. Determine key parameters. Based on the results of mechanical model analysis, determine the key parameters that affect the reinforcement effect, including the thickness of the carbon fiber cloth. Select 2mm, 3mm, and 4mm for experimental comparison; the number of layers. Select single or multi-layer according to the reinforcement requirements, not more than 4 layers; the size of prestress. The optimal prestress range is 30%-50% of the design bearing capacity of the segment; the tensioning speed. Set 0.5MPa / min, 1MPa / min, and 1.5MPa / min for experiments; the tensioning sequence and the type and performance of the adhesive. Optimize these parameters through a combination of experimental verification and numerical simulation to ensure the best reinforcement effect;

[0088] Step S20 specifically includes the following steps:

[0089] S201, based on the preliminary results of the finite element analysis in step S10, identify the key parameters that have a significant impact on the reinforcement effect, including the thickness, number of layers, prestressing size, tensioning speed, tensioning sequence of the carbon fiber cloth, and the type and performance of the adhesive, etc. According to experience and preliminary analysis, select one or more initial values ​​or ranges for each parameter for further research;

[0090] S202. Design a detailed experimental plan for each key parameter. For example, for the thickness of carbon fiber cloth, select three different thicknesses of 2mm, 3mm, and 4mm for experimental comparison; for the prestressing size, set several specific prestressing levels within the range of 30%-50% of the design bearing capacity of the segment for testing; for the tensioning speed, set three speeds of 0.5MPa / min, 1MPa / min, and 1.5MPa / min for the experiment, and at the same time, determine the number of samples, loading conditions, measurement methods, etc. required for the experiment;

[0091] Specifically, the detailed experimental plan includes the following steps:

[0092] Determine the purpose and scope of the experiment, clarify the key parameters that the experiment aims to study and their impact on the reinforcement effect, and set a reasonable parameter range and experimental conditions.

[0093] Design experimental plans. According to different values ​​of key parameters, design detailed experimental plans, including preparation of experimental samples, loading conditions, measurement methods, data recording, etc.

[0094] Prepare experimental materials and equipment. According to the experimental plan, prepare the required carbon fiber cloth, adhesive, shield segment samples, loading equipment, measuring instruments, etc.

[0095] Carry out the experiment and conduct the experiment step by step according to the experimental plan. During the experiment, ensure that all operations are in compliance with the specifications and the data records are accurate and complete.

[0096] Data collection and analysis: collect all data during the experiment, including the strain of carbon fiber cloth, stress and displacement of the segment structure, and conduct detailed analysis and comparison.

[0097] Result evaluation and conclusion,Based on the data analysis results, the influence of different parameter values,on the reinforcement effect is evaluated and the experimental conclusions,are drawn.

[0098] S203. Conduct experiments one by one according to the experimental design. During the experiment, the experimental conditions need to be strictly controlled to ensure the accuracy and repeatability of the experimental results, and key data during the experiment, such as stress changes, deformation, failure mode, etc., should be recorded;

[0099] S204, using finite element analysis software ANSYS, establishing a corresponding numerical model according to the experimental conditions, performing numerical simulation, comparing the numerical simulation results with the experimental results, verifying the accuracy and reliability of the model, and if there are differences, analyzing the reasons and adjusting the model;

[0100] S205. Based on the results of experiments and numerical simulations, optimize key parameters, analyze the impact of different parameters on the reinforcement effect, and determine the best parameter combination. It may require multiple iterations, by continuously adjusting parameter values ​​and repeating the experiments and numerical simulation processes until the optimal reinforcement solution is found.

[0101] The in-depth exploration and optimization process of the key parameters of the shield segment reinforcement effect in step S20 has the following significant beneficial effects: first, the key parameters that have a significant impact on the reinforcement effect are identified through preliminary finite element analysis, which points out the direction for subsequent detailed research, avoids blind trial and error, and improves research efficiency; second, a detailed experimental plan is designed for each key parameter to ensure that the experiment is systematic and comparable, and can comprehensively evaluate the impact of each parameter on the reinforcement effect; third, by combining experiments with numerical simulations, the accuracy of the model is verified by comparison, the reliability of the simulation results is improved, and more accurate theoretical support is provided for actual projects; finally, based on the iterative optimization process of experiments and numerical simulations, the best parameter combination can be accurately determined, and the optimal reinforcement plan can be formulated, which not only ensures the reinforcement effect, but also reduces the construction cost, with significant economic and technical benefits.

[0102] Specifically, in one embodiment, in a subway shield tunnel reinforcement project in a certain city, in order to further optimize the reinforcement scheme, according to the preliminary results of the finite element analysis of step S10, it is found that the thickness of the carbon fiber cloth, the size of the prestress and the tensioning speed have a significant impact on the reinforcement effect. Therefore, in step S20, these key parameters are studied and optimized in detail. In the S201 stage, the thickness of the carbon fiber cloth is determined to be 2mm, 3mm, and 4mm. The prestress is tested at three levels of 35%, 40%, and 45% of the design bearing capacity of the pipe segment. The tensioning speed is set to 0.5MPa / min, 1MPa / min, and 1.5MPa / min. In the S202 stage, a detailed experimental plan is designed for each parameter, including sample preparation, loading device design, data acquisition system, etc., and the number of samples, loading conditions and measurement methods required for the experiment are clarified. In the S203 stage, the experiments are carried out one by one in strict accordance with the experimental design, and the experimental conditions, such as ambient temperature and humidity, are strictly controlled during the experiment. etc. to ensure the accuracy and repeatability of the experimental results. At the same time, key data such as stress changes, deformation and failure modes during the experiment were recorded in detail. Subsequently, in the S204 stage, the corresponding numerical model was established according to the experimental conditions using ANSYS finite element analysis software, and numerical simulation was carried out. After the simulation was completed, the numerical simulation results were compared with the experimental results, and it was found that the two were highly consistent, which verified the accuracy of the model. For individual differences, in-depth analysis was carried out, and the model was adjusted accordingly. Finally, in the S205 stage, based on the results of experiments and numerical simulations, key parameters such as carbon fiber cloth thickness, prestress size and tensioning speed were optimized and analyzed. Through multiple iterations, the parameter values ​​were continuously adjusted and the experiments and numerical simulation processes were repeated. Finally, the optimal parameter combination of 3mm carbon fiber cloth thickness, 40% prestress size of the segment design bearing capacity and 1MPa / min tensioning speed was determined. This result provided strong support for the formulation of the optimal reinforcement plan and actual construction.

[0103] When conducting numerical simulation, it is also necessary to ensure the accuracy of the input data, verify the numerical simulation results, and compare them with the experimental data to ensure consistency between the two. When optimizing key parameters, in addition to considering the impact of a single parameter on the reinforcement effect, the interaction between multiple parameters should also be analyzed. By designing multi-factor experiments or using statistical methods such as variance analysis and regression analysis, the comprehensive impact of different parameter combinations on the reinforcement effect can be studied.

[0104] Specifically, in one embodiment, a multi-factor experimental design is performed and the parameter interaction analysis is performed. The experimental background is that in the carbon fiber cloth prestressed tensioning shield segment reinforcement method, we have determined several key parameters: the thickness (T) of the carbon fiber cloth, the number of layers (L), the prestress size (P), the tensioning speed (V), and the type and performance of the adhesive (here simplified as a comprehensive index A, representing the bonding strength and durability of the adhesive). In order to optimize these parameters, we need to consider the interaction between them and design a multi-factor experiment to study their comprehensive impact on the reinforcement effect.

[0105] (1) Experimental design

[0106] Select parameter ranges and levels: carbon fiber cloth thickness (T) is 2mm, 3mm, and 4mm; the number of layers (L) is 1 layer, 2 layers, and 3 layers; the prestressing size (P) is 30%, 40%, and 50% of the design bearing capacity of the segment; the tensioning speed (V) is 0.5MPa / min, 1MPa / min, and 1.5MPa / min; the adhesive performance (A) is high, medium, and low (representing different bonding strengths and durability).

[0107] (2) Design of experimental plan

[0108] A full factorial design is used, that is, all level combinations of all parameters are tested. This will generate 3^5=243 experimental combinations, but in practical applications, due to resource and time constraints, we may choose to experiment with some combinations. In order to simplify the experiment, Latin Hypercube Sampling (LHS) or Orthogonal Design can be used to select representative experimental combinations.

[0109] (3) Experimental implementation

[0110] Prepare experimental materials and equipment according to the selected experimental combination, and conduct experiments according to the predetermined experimental conditions. During the experiment, strictly control the experimental conditions to ensure the accuracy and repeatability of the experimental results. Record key data during the experiment, such as stress changes, deformation, failure mode, etc.

[0111] (4) Data analysis

[0112] Analysis of variance (ANOVA): Use ANOVA to assess the effect of each parameter and their interactions on the reinforcement effect. Determine which parameters and interactions have a significant effect on the reinforcement effect.

[0113] Regression analysis: Use multiple linear regression or nonlinear regression models to establish the mathematical relationship between parameters and reinforcement effects. Through regression analysis, the reinforcement effects under different parameter combinations can be predicted.

[0114] Interaction analysis: Analyze the interaction between different parameters to understand how they jointly affect the reinforcement effect. For example, you can analyze the interaction between the thickness and number of carbon fiber cloth layers to understand their combined impact on the reinforcement effect. You can also analyze the interaction between the prestressing size and the tensioning speed to understand their dynamic impact on the reinforcement effect.

[0115] (5) Results and Optimization

[0116] Determine the best parameter combination: Determine the best parameter combination based on the results of variance analysis and regression analysis; consider the interaction between parameters to ensure that the selected parameter combination is optimal overall.

[0117] Verification and optimization: Experimental verification is performed on the selected optimal parameter combination to ensure that the reinforcement effect meets expectations; if the experimental results do not meet expectations, further parameter adjustments and optimizations are performed.

[0118] For the specific interaction analysis in the example, suppose we conducted some experiments and obtained the following results: when the carbon fiber cloth is thin (such as 2 mm) and the number of layers is small (such as 1 layer), the effect of prestress on the reinforcement effect is small; but when the thickness increases (such as 4 mm) and the number of layers increases (such as 3 layers), the effect of prestress becomes significant.

[0119] The effect of tensioning speed on the reinforcement effect is related to the performance of the adhesive. When the adhesive performance is high, the effect of tensioning speed on the reinforcement effect is small; but when the adhesive performance is low, the effect of tensioning speed becomes significant.

[0120] These results indicate that the interactions between parameters have an important influence on the reinforcement effect. Therefore, when optimizing parameters, we need to consider these interactions and design multi-factor experiments to study their combined effects on the reinforcement effect.

[0121] Through the above examples, we can better understand how to design multi-factor experiments to analyze the interaction between parameters and optimize the key parameters in the carbon fiber cloth prestressed tensioned shield segment reinforcement method.

[0122] It is emphasized that ensuring the accuracy of input data during numerical simulation is the basis for improving the reliability of simulation results. Through strict data review and preprocessing, the impact of data errors on simulation results can be reduced, making the simulation process closer to actual working conditions. Secondly, verifying the numerical simulation results and comparing them with experimental data is a key step in verifying the effectiveness of the model. This step can timely discover deviations in the simulation process and ensure the consistency between simulation results and experimental data by adjusting model parameters or improving simulation methods. This not only enhances the credibility of simulation results, but also provides a reliable basis for subsequent optimization work. When optimizing key parameters, a more comprehensive analysis method is proposed. In addition to considering the impact of a single parameter on the reinforcement effect, the interaction between multiple parameters is also deeply analyzed. This comprehensive consideration of multiple factors makes the optimization process more in line with the complex situation in actual engineering. By designing multi-factor experiments or using statistical methods such as variance analysis and regression analysis, the comprehensive impact of different parameter combinations on the reinforcement effect can be systematically studied, so as to find the optimal parameter combination and maximize the reinforcement effect.

[0123] S30. Data collection and analysis. During the reinforcement process, various key data are collected and recorded in real time, including the real-time change of tension force, strain distribution of carbon fiber cloth, stress response of segment structure, etc. The strain distribution of carbon fiber cloth and stress change of segment structure are measured by strain gauges, fiber grating sensors, strain gauges or strain rosettes, etc. The collected data are analyzed in detail to verify the accuracy of the mechanical model and the rationality of parameter setting. According to the analysis results, the reinforcement plan is adjusted in time.

[0124] Step S30 specifically includes the following steps:

[0125] S301. Equipment preparation and installation: Select and prepare measuring equipment such as strain gauges, fiber grating sensors, stress gauges or strain gauges, and ensure that these equipment have been calibrated to meet the measurement accuracy requirements. On the reinforced segment structure, install and fix the measuring equipment according to the predetermined measurement point arrangement plan to ensure that the equipment is installed in an accurate position and can accurately reflect the strain distribution of the carbon fiber cloth and the stress changes of the segment structure.

[0126] S302, data acquisition system startup: build and start the data acquisition system, connect the measuring equipment with the data acquisition device such as a data acquisition instrument, a computer, etc., set the data acquisition parameters such as sampling frequency, storage path, etc., to ensure that data can be collected in real time and accurately;

[0127] S303, real-time data collection, during the reinforcement process, start the data acquisition system to collect and record various key data in real time, including real-time changes in tension, strain distribution of carbon fiber cloth, stress response of segment structure, etc., to ensure the integrity and accuracy of data records, and regularly check the operating status of the data acquisition system to prevent data loss or errors;

[0128] S304, data preprocessing, preprocessing the collected data, including data cleaning to remove outliers, noise, etc., data calibration and comparison with standard values, data filtering to remove high-frequency noise, etc., to improve the accuracy and reliability of data analysis;

[0129] S305, data analysis, using statistical analysis, signal processing, image recognition and other methods, to conduct detailed analysis on the pre-processed data, analyze the strain distribution law of the carbon fiber cloth, including the size, direction, and change trend of the strain, analyze the stress response characteristics of the segment structure, including the distribution, size, and change trend of the stress, and whether there are stress concentration or abnormal stress phenomena, compare the analysis results with the prediction results of the mechanical model, and verify the accuracy of the mechanical model and the rationality of the parameter setting;

[0130] S306. Evaluation and adjustment of reinforcement scheme: Based on the data analysis results, evaluate the current reinforcement scheme to see whether the reinforcement effect has achieved the expected goal and whether there are areas that need improvement. If the reinforcement effect is not ideal or there are areas that need improvement, adjust the reinforcement scheme in a timely manner based on the data analysis results and the prediction results of the mechanical model. The adjustments may include key parameters such as the thickness of the carbon fiber cloth, the number of layers, the size of the prestress, the tensioning speed, and the tensioning sequence. After adjusting the reinforcement scheme, re-analyze the data to verify whether the adjusted effect meets expectations.

[0131] Through a strict equipment preparation and installation process, the accuracy and reliability of the measuring equipment are ensured, laying the foundation for collecting high-quality data; secondly, the real-time data collection and preprocessing links ensure the integrity and accuracy of the data, effectively eliminate outliers and noise interference, and provide a clean and reliable data source for subsequent data analysis; thirdly, through the comprehensive use of statistical analysis, signal processing, image recognition and other methods, the pre-processed data is deeply analyzed, which not only reveals the detailed characteristics of the strain distribution of carbon fiber cloth and the stress response of the segment structure, but also verifies the accuracy of the mechanical model and the rationality of the parameter setting through comparison, providing a scientific basis for the evaluation and adjustment of the reinforcement scheme; finally, the reinforcement scheme evaluation and adjustment process based on the data analysis results realizes the instant feedback and dynamic optimization of the reinforcement effect, ensures the quality and efficiency of the reinforcement project, and reduces the construction risk and cost.

[0132] In a subway shield tunnel segment reinforcement project, the preliminary design and finite element analysis were completed according to step S10, and a reinforcement plan was formulated based on the optimization results of step S20. Then, the on-site monitoring and data analysis stage of step S30 was entered. In S301, the project team selected calibrated strain gauges, fiber grating sensors and other equipment, and accurately installed these measuring equipment on the reinforced segment structure according to the predetermined measurement point layout plan. At the same time, it was ensured that all equipment was firmly fixed and could accurately reflect the strain distribution of the carbon fiber cloth and the stress changes of the segment structure. Entering S302, the project team built a data acquisition system, connected the measuring equipment with data acquisition instruments, computers and other equipment, and set a reasonable sampling frequency and storage path. After the system was started, real-time collection of key data was realized. In S303, as the reinforcement process progressed, the data acquisition system continued to run, recording key data such as changes in tension, strain distribution of carbon fiber cloth and stress response of the segment structure in real time. The project team regularly checked the system operation status to ensure the integrity of data records. and accuracy. After completing data collection, the project team entered the data preprocessing stage of S304. The project team cleaned, calibrated and filtered the data, removed outliers, noise and high-frequency interference, and prepared a high-quality data set for subsequent data analysis. In S305, the project team used statistical analysis, signal processing and other methods to conduct an in-depth analysis of the preprocessed data. By analyzing the strain distribution law of the carbon fiber cloth and the stress response characteristics of the segment structure, and comparing them with the predicted results of the mechanical model, the accuracy of the model and the rationality of the parameter setting were verified. At the same time, the local stress concentration phenomenon was also found, which provided a basis for the subsequent adjustment of the reinforcement plan. Finally, in S306, the project team evaluated the current reinforcement plan based on the data analysis results and found that although the overall reinforcement effect was good, there was a stress concentration problem in the local area. Therefore, the team decided to adjust the key parameters such as the thickness and tensioning sequence of the carbon fiber cloth, and re-analyzed the data. The results showed that the adjusted reinforcement plan effectively alleviated the stress concentration problem and achieved the expected reinforcement effect.

[0133] After data cleaning, calibration and filtering, data verification is performed to ensure that the preprocessed data conforms to the actual situation and expected goals. For abnormal data found during the preprocessing process, an exception handling process should be formulated, including anomaly identification, cause analysis and handling measures.

[0134] In the monitoring and data analysis process of shield segment reinforcement projects, the accuracy and reliability of data are the basis for evaluating the reinforcement effect and optimizing the reinforcement plan. However, due to the complexity of the on-site environment, the limitations of the measuring equipment and the uncertainty of human operation, the collected raw data often contain unfavorable factors such as noise and outliers. If these factors are not properly handled, they will directly affect the accuracy and reliability of subsequent data analysis. By introducing the data verification link, it is ensured that the pre-processed data has not only undergone routine processing such as cleaning, calibration and filtering, but also undergone strict verification to confirm that it conforms to the actual situation and expected goals. The addition of this step effectively reduces data errors. The impact on the analysis results improves the accuracy and credibility of data analysis. At the same time, for the abnormal data that may be found in the preprocessing process, it also proposes the necessity of formulating anomaly handling procedures. This process includes three key steps: anomaly identification, cause analysis and treatment measures. It aims to timely discover and handle anomalies in the data through a systematic approach. Anomaly identification can accurately mark abnormal points in the data and provide warnings for subsequent analysis; cause analysis can deeply explore the root causes of abnormal data and provide direction for problem solving; treatment measures take targeted measures to correct or eliminate the data based on the results of cause analysis to ensure the integrity and consistency of the data set.

[0135] S40. Implement reinforcement. According to the optimized parameters and model guidance, implement carbon fiber cloth prestressed tension reinforcement. During the reinforcement process, strictly control various operating parameters to ensure that the reinforcement effect meets the expectations. After the reinforcement is completed, conduct a comprehensive evaluation of the reinforcement effect, including tests on structural strength, stiffness, stability and durability, to ensure that the reinforcement effect meets the design requirements.

[0136] Step S40 specifically includes the following steps:

[0137] S401. According to the optimized reinforcement plan, prepare the required carbon fiber cloth, prestressed tensioning equipment, adhesives, supporting materials, etc., and ensure that the quality of all materials meets the standards. Check whether the prestressed tensioning equipment and measuring instruments are intact to ensure that they can operate normally and accurately measure during the construction process. Set up safety warning signs at the reinforcement site to ensure the safe isolation of the construction area. At the same time, prepare the scaffolding and lighting equipment required for construction;

[0138] S402. Clean the surface of the reinforced segment structure to remove dirt, oil stains, rust, etc. to ensure that the surface is clean and flat. If necessary, perform surface repair to improve the bonding between the carbon fiber cloth and the structure. Apply a layer of special bonding primer, usually epoxy resin adhesive, on the surface of the structure to improve the bonding effect between the carbon fiber cloth and the surface of the structure. Note that the primer should be applied evenly and without omissions. According to the design plan, cut the carbon fiber cloth into a suitable size and shape and install it to the predetermined position to ensure that the carbon fiber cloth fits tightly to the surface of the structure without wrinkles or bubbles. Install the prestressing equipment and adjust it. To the appropriate tension, according to the optimized parameter model, set the tensioning speed and tensioning force to ensure that the tensioning process is smooth and controllable, start the tensioning equipment, and prestress the carbon fiber cloth. During the tensioning process, strictly control various operating parameters such as tensioning speed and tensioning force to ensure that the tensioning effect meets the design requirements. At the same time, pay attention to observe the strain distribution of the carbon fiber cloth and the stress response of the segment structure, and adjust the tensioning strategy in time. After the carbon fiber cloth is tensioned, wait for it to be fully cured according to the curing requirements of the adhesive. During the curing period, pay attention to keeping the temperature, humidity and other conditions of the construction environment stable to ensure the curing effect;

[0139] S403. After the reinforcement is completed, first conduct an appearance inspection to check whether the carbon fiber cloth is flat, without wrinkles, bubbles and other defects. At the same time, check whether the tensioning equipment has been removed and whether the construction area is tidy. Conduct a comprehensive assessment of the reinforced structure, including tests on structural strength, stiffness, stability and durability. The test method can be selected according to the design requirements and relevant standards, such as using a tensile tester to test the structural strength and using a vibration tester to test the structural stiffness. Compare and analyze the test results with the design requirements to evaluate whether the reinforcement effect meets the requirements. If it is found that the requirements are not met, the cause should be found in time and corresponding remedial measures should be taken. The various data, test results and evaluation conclusions during the reinforcement process should be compiled into a report for subsequent reference and archiving. The report should include the reinforcement plan, construction steps, test methods, test results and evaluation conclusions.

[0140] Through meticulous material preparation and inspection, the quality of materials and the integrity of construction equipment required for the reinforcement project were ensured, providing a strong guarantee for the smooth progress of the reinforcement construction; secondly, during the reinforcement construction process, the cleaning and repair of the surface of the segment structure, the uniform coating of the primer, the precise cutting and installation of the carbon fiber cloth, the precise regulation of the prestressing tensioning equipment, and the strict control of the tensioning process all effectively improved the construction quality of the reinforcement project, ensuring the good bonding of the carbon fiber cloth and the segment structure and the accuracy of the prestressing tensioning effect; finally, the comprehensive evaluation and report preparation after the reinforcement was completed not only provided a scientific basis for the verification of the reinforcement effect, but also provided valuable reference experience for subsequent similar projects. The strict implementation of this series of steps significantly improved the safety and reliability of the shield segment reinforcement project, reduced construction risks, and extended the service life of the tunnel structure.

[0141] In a subway shield tunnel segment reinforcement project, after the preliminary design and finite element analysis of step S10, and the numerical simulation and parameter optimization of step S20, the project team entered the reinforcement construction stage of step S40. In the S401 stage, the project team carefully prepared carbon fiber cloth, prestressed tensioning equipment, high-quality epoxy resin adhesive and necessary supporting materials according to the optimized reinforcement plan. At the same time, all construction equipment was comprehensively inspected to ensure that they were in good condition. At the reinforcement site, conspicuous safety warning signs were set up, and stable scaffolding was built, equipped with sufficient lighting equipment, providing a safe and convenient environment for construction. Entering the S402 stage, the project team first thoroughly cleaned the surface of the segment structure to remove unfavorable factors such as dirt, oil stains and rust. Subsequently, a layer of special epoxy resin adhesive was evenly applied on the surface of the structure to improve the bonding effect between the carbon fiber cloth and the structure. According to the design plan, the carbon fiber cloth was cut into suitable sizes and shapes and installed strictly in accordance with the predetermined position. During the installation process, the project team ensured that the carbon fiber The cloth fits tightly with the surface of the structure without wrinkles or bubbles. Subsequently, the prestressed tensioning equipment was installed, and the tensioning speed and tensioning force were set according to the optimized parameter model. After starting the tensioning equipment, the project team strictly monitored various operating parameters to ensure the smooth and controllable tensioning process. At the same time, by real-time monitoring the strain distribution of the carbon fiber cloth and the stress response of the segment structure, the tensioning strategy was adjusted in time to ensure that the tensioning effect met the design requirements. After the carbon fiber cloth was tensioned, the project team waited for it to be fully cured according to the curing requirements of the adhesive, and ensured that the temperature, humidity and other conditions of the construction environment were stable. Finally, in the S403 stage, the project team conducted a comprehensive evaluation of the reinforced structure. Through appearance inspection, structural strength test, stiffness test and other test methods, it was verified whether the reinforcement effect met the design requirements. The test results showed that the strength and stiffness of the reinforced segment structure were significantly improved, and the stability and durability were also effectively enhanced. The project team organized the various data, test results and evaluation conclusions in the reinforcement process into a detailed report, which provided valuable reference for subsequent similar projects.

[0142] This method first constructs a highly simulated three-dimensional solid mechanical model through detailed data collection and modeling. The model integrates the actual structural dimensions, material properties, damage conditions and mechanical properties of the shield segment. Using ANSYS finite element software, this model not only considers the geometric shape, boundary conditions and load distribution of the segment, but also introduces the prestressing effect to simulate the influence of carbon fiber cloth on the structural stress of the segment under different prestressing levels. Through simulation calculation, the optimal range and method of prestressing can be accurately predicted and determined, providing a scientific basis for subsequent reinforcement implementation. Then, based on the analysis of the mechanical model, a series of key parameters affecting the reinforcement effect are determined, including the thickness, number of layers, prestressing size, tensioning speed, tensioning sequence of carbon fiber cloth, and the type and performance of adhesives. The setting of these parameters is not arbitrary, but based on in-depth research on experimental verification and numerical simulation, and through continuous optimization and adjustment, to ensure that the reinforcement scheme can achieve the best effect. During the reinforcement implementation process, this method emphasizes real-time data collection and analysis. Advanced measuring equipment, such as strain gauges, fiber Bragg grating sensors, stress gauges or strain rosettes, are used to accurately measure the real-time changes in tension, the strain distribution of carbon fiber cloth, and the stress response of the segment structure. Through detailed analysis of these data, not only can the accuracy of the mechanical model and the rationality of the parameter setting be verified, but also the reinforcement scheme can be adjusted in time according to the analysis results to ensure that the reinforcement process is always in a controllable state. Finally, after the reinforcement is completed, the method requires a comprehensive and rigorous evaluation of the reinforcement effect. This includes tests in multiple aspects such as structural strength, stiffness, stability and durability, aiming to fully verify whether the reinforcement effect meets the design requirements. Through these evaluation measures, it can be ensured that the reinforced shield segment structure can operate safely and reliably, effectively extending its service life. In summary, the working principle of the carbon fiber cloth prestressed tensioned shield segment reinforcement method is to achieve precise reinforcement and performance improvement of the shield segment structure through a series of steps such as scientific modeling, parameter optimization, data-driven and effect evaluation.

[0143] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0144] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for reinforcing shield segments using prestressed carbon fiber cloth, characterized in that: The following steps are involved: S10. Establish a mechanical model; collect the actual structural dimensions, material properties and damage data of the shield segments, use ANSYS finite element software, establish a three-dimensional solid model based on the collected data, consider the geometric shape, boundary conditions, load distribution and mechanical properties of the reinforcement materials of the segments, introduce the prestressing effect into the model, analyze the influence of carbon fiber cloth on the segment structural stress at different prestress levels, and determine the optimal prestressing range and method through simulation calculation; S20. Determine key parameters. Based on the results of mechanical model analysis, determine the key parameters that affect the reinforcement effect, including the thickness, number of layers, prestress, tensioning speed, tensioning sequence of the carbon fiber cloth, and the type and performance of the adhesive. Optimize these parameters through a combination of experimental verification and numerical simulation to ensure the best reinforcement effect. S30, data collection and analysis: During the reinforcement process, various key data are collected and recorded in real time, including the real-time change of tension force, the strain distribution of carbon fiber cloth, and the stress response of the segment structure; strain gauges, fiber grating sensors, strain gauges or strain gauges are used to measure the strain distribution of carbon fiber cloth and the stress change of the segment structure, respectively, and the collected data are analyzed in detail to verify the accuracy of the mechanical model and the rationality of the parameter setting; Adjust the reinforcement plan in a timely manner according to the analysis results; S40. Implement reinforcement. According to the optimized parameters and model guidance, implement carbon fiber cloth prestressed tension reinforcement. During the reinforcement process, strictly control various operating parameters to ensure that the reinforcement effect meets expectations. After the reinforcement is completed, conduct a comprehensive evaluation of the reinforcement effect, including tests on structural strength, stiffness, stability and durability, to ensure that the reinforcement effect meets the design requirements.

2. A method for reinforcing shield segments with prestressed carbon fiber cloth according to claim 1, characterized in that: Step S10 specifically includes the following steps: S101. Data collection and collation: On-site measurements or review of design documents to collect the actual structural dimensions of the shield segments, including the segment diameter, thickness, ring width, location and size of the longitudinal and ring seams, obtain the segment material property data, and the yield strength, diameter, and spacing of the steel bars, and evaluate and record the damage of the segments, including the location, length, width, depth, and possible damage types of the cracks; S102, finite element software selection and setting; select ANSYS as the finite element analysis software, start the specific module or toolbox in the ANSYS finite element analysis software that is suitable for the current analysis needs, set the analysis type, and select static analysis or nonlinear analysis to consider the nonlinearity of the material and the geometric nonlinearity of the structure; S103, 3D solid model construction: based on the collected structural dimension data, draw the 3D geometric model of the segment in ANSYS, use the modeling tools provided by ANSYS, or import the CAD model for conversion, define the material properties, input the collected concrete and steel bar material properties into the material library of ANSYS, and assign them to the corresponding parts in the model, divide the mesh, and divide the model with appropriate mesh type and size to ensure calculation accuracy and efficiency; S104, boundary conditions and load application: according to the actual working conditions of the segment, boundary conditions such as fixed constraints and sliding constraints are set to simulate the actual stress conditions of the segment in the tunnel, and loads are applied, including hydrostatic pressure, earth pressure, and construction loads, to ensure that the load distribution is consistent with the actual situation; S105, prestressed tensioning effect simulation: introduce carbon fiber cloth reinforcement layer into the model, define the material properties and cross-sectional characteristics of carbon fiber cloth, set prestressed tensioning simulation, and simulate the tensioning effect of carbon fiber cloth under different prestressing levels by applying temperature load, displacement load or special prestressed unit method; S106, Analysis and Optimization: Run simulation calculations to analyze the stress distribution and deformation of the segment structure under different prestressing levels and evaluate the reinforcement effect; compare the stress state before and after reinforcement to determine the optimal prestressing range and method; adjust the model parameters or reinforcement scheme according to the analysis results and perform iterative optimization until a satisfactory reinforcement effect is achieved; S107. Result verification and output: verify the rationality and accuracy of the simulation results, compare them with experimental data or actual observation results, and output the simulation results, including stress cloud map, displacement cloud map, and prestress distribution map, to provide a scientific basis for subsequent reinforcement construction.

3. A method for reinforcing shield segments with prestressed carbon fiber cloth according to claim 2, characterized in that: In step S103, after the three-dimensional solid model is constructed, the accuracy of the model will be tested using known or verifiable working conditions, the predictive ability of the model will be verified using known experimental data or previous analysis results, and adjustments or calibrations will be made as needed to ensure that the model can accurately reflect the actual physical behavior. In step S107, the uncertainty and potential risks in the simulation results will be evaluated, and the impact of these uncertainties and risks on the reinforcement effect will be quantified. By considering the changes in material properties, the uncertainty of loads, and the limitations of model assumptions, a more robust reinforcement plan can be formulated to provide support for decision-making during the construction process.

4. The method for reinforcing shield segments with prestressed carbon fiber cloth according to claim 1 is characterized in that: Step S20 specifically includes the following steps: S201, based on the preliminary results of the finite element analysis in step S10, identify key parameters that have a significant impact on the reinforcement effect, including the thickness, number of layers, prestressing size, tensioning speed, tensioning sequence of the carbon fiber cloth, and the type and performance of the adhesive, and select one or more initial values ​​or ranges for each parameter for further research based on experience and preliminary analysis; S202. Design a detailed experimental plan for each key parameter; S203. Conduct experiments one by one according to the experimental design. During the experiments, the experimental conditions need to be strictly controlled to ensure the accuracy and repeatability of the experimental results, and key data during the experiments, such as stress changes, deformation conditions, and failure modes, should be recorded; S204, using finite element analysis software ANSYS, establishing a corresponding numerical model according to the experimental conditions, performing numerical simulation, comparing the numerical simulation results with the experimental results, verifying the accuracy and reliability of the model, and if there are differences, analyzing the reasons and adjusting the model; S205. Based on the results of experiments and numerical simulations, key parameters are optimized, the influence of different parameters on the reinforcement effect is analyzed, and the best parameter combination is determined. Multiple iterations are required to continuously adjust parameter values ​​and repeat the experiments and numerical simulation processes until the optimal reinforcement solution is found.

5. A method for reinforcing shield segments with prestressed carbon fiber cloth according to claim 4, characterized in that: When conducting numerical simulation, it is also necessary to ensure the accuracy of the input data, verify the numerical simulation results, and compare them with the experimental data to ensure consistency between the two. When optimizing key parameters, in addition to considering the impact of a single parameter on the reinforcement effect, analyze the interaction between multiple parameters and study the comprehensive impact of different parameter combinations on the reinforcement effect by designing multi-factor experiments or using statistical methods.

6. The method for reinforcing shield segments with prestressed carbon fiber cloth according to claim 1, characterized in that: Step S30 specifically includes the following steps: S301. Equipment preparation and installation: Select and prepare strain gauges, fiber grating sensors, stress gauges or strain gauges, and ensure that these devices have been calibrated to meet the measurement accuracy requirements. On the reinforced segment structure, install and fix the measurement equipment according to the predetermined measurement point arrangement plan to ensure that the equipment is installed in an accurate position and can accurately reflect the strain distribution of the carbon fiber cloth and the stress changes of the segment structure. S302, data acquisition system startup, build and start the data acquisition system, connect the measuring equipment to the data acquisition device, set the data acquisition parameters, and ensure that data can be collected in real time and accurately; S303, real-time data collection, during the reinforcement process, start the data acquisition system to collect and record various key data in real time, including real-time changes in tension, strain distribution of carbon fiber cloth, and stress response of segment structure, to ensure the integrity and accuracy of data records, and regularly check the operating status of the data acquisition system to prevent data loss or errors; S304, data preprocessing, preprocessing the collected data, including data cleaning to remove outliers and noise, data calibration and comparison with standard values, and data filtering to remove high-frequency noise, so as to improve the accuracy and reliability of data analysis; S305, data analysis, using statistical analysis, signal processing, image recognition methods, to conduct detailed analysis on the pre-processed data, analyze the strain distribution law of the carbon fiber cloth, including the size, direction, and change trend of the strain, analyze the stress response characteristics of the segment structure, including the distribution, size, and change trend of the stress, and whether there is stress concentration or abnormal stress phenomenon, compare the analysis results with the prediction results of the mechanical model, and verify the accuracy of the mechanical model and the rationality of the parameter setting; S306. Evaluation and adjustment of reinforcement scheme: Based on the data analysis results, the current reinforcement scheme is evaluated to assess whether the reinforcement effect has achieved the expected goal and whether there are areas that need improvement. If the reinforcement effect is not ideal or there are areas that need improvement, the reinforcement scheme is adjusted in a timely manner based on the data analysis results and the prediction results of the mechanical model. The adjustments may include the thickness of the carbon fiber cloth, the number of layers, the size of the prestress, the tensioning speed, and the tensioning sequence. After adjusting the reinforcement scheme, re-analyze the data to verify whether the adjusted effect meets expectations.

7. The method for reinforcing shield segments with carbon fiber cloth prestressed tensioning according to claim 1 is characterized in that: After data cleaning, calibration and filtering, data verification is performed to ensure that the preprocessed data conforms to the actual situation and expected goals. For abnormal data found during the preprocessing process, an exception handling process should be formulated, including anomaly identification, cause analysis and handling measures.

8. The method for reinforcing shield segments with prestressed carbon fiber cloth according to claim 1, characterized in that: Step S40 specifically includes the following steps: S401. According to the optimized reinforcement plan, prepare the required carbon fiber cloth, prestressed tensioning equipment, adhesives, and supporting materials, and ensure that the quality of all materials meets the standards. Check whether the prestressed tensioning equipment and measuring instruments are intact to ensure that they can operate normally and accurately measure during the construction process. Set up safety warning signs at the reinforcement site to ensure the safe isolation of the construction area, and prepare the scaffolding and lighting equipment required for construction; S402. Clean the surface of the reinforced segment structure to remove dirt, oil stains, and rust to ensure that the surface is clean and flat. If necessary, perform surface repair to improve the bonding between the carbon fiber cloth and the structure. Apply a layer of special bonding primer, usually epoxy resin adhesive, on the surface of the structure to improve the bonding effect between the carbon fiber cloth and the surface of the structure. Note that the primer should be applied evenly and without omissions. According to the design plan, cut the carbon fiber cloth into a suitable size and shape and install it to the predetermined position to ensure that the carbon fiber cloth fits tightly to the surface of the structure without wrinkles or bubbles. Install the prestressing equipment and adjust it. To the appropriate tension, according to the optimized parameter model, set the tensioning speed and tensioning force to ensure that the tensioning process is smooth and controllable, start the tensioning equipment, and prestress the carbon fiber cloth. During the tensioning process, strictly control various operating parameters such as tensioning speed and tensioning force to ensure that the tensioning effect meets the design requirements. At the same time, pay attention to observe the strain distribution of the carbon fiber cloth and the stress response of the segment structure, and adjust the tensioning strategy in time. After the carbon fiber cloth is tensioned, wait for it to be fully cured according to the curing requirements of the adhesive. During the curing period, pay attention to keeping the temperature and humidity conditions of the construction environment stable to ensure the curing effect; S403. After the reinforcement is completed, first conduct an appearance inspection to check whether the carbon fiber cloth is flat, wrinkle-free, and bubble-free. At the same time, check whether the tensioning equipment has been removed and the construction area is tidy. Conduct a comprehensive assessment of the reinforced structure, including tests on structural strength, stiffness, stability, and durability. The test method can be selected according to the design requirements and relevant standards, such as using a tensile tester to test the structural strength and using a vibration tester to test the structural stiffness. Compare and analyze the test results with the design requirements to assess whether the reinforcement effect meets the requirements. If any non-compliance is found, find the cause in a timely manner and take appropriate remedial measures. Organize the various data, test results, and evaluation conclusions during the reinforcement process into a report for subsequent reference and archiving. The report should include the reinforcement plan, construction steps, test methods, test results, and evaluation conclusions.

Images