A prestressed square pile structure optimization method based on damage identification and boundary adjustment

Abstract

The application discloses a prestressed square pile structure optimization method based on damage identification and boundary adjustment. First, an initial finite element model of the pile body is established, and a region with a damage factor greater than 0.5 is extracted as a weak region, which is parameterized and an improvement scheme is designed. The whole model of the pile body is divided into a local model to be optimized and a remaining model, and a connection constraint is established at the segmentation boundary. When the parameters of the local model change, the nodes or meshes near the boundary of the remaining model are synchronously adjusted according to the boundary node coordinates to maintain the overall continuous stress. The weak region is iteratively optimized through finite element analysis. Finally, based on the optimization results, a unified reinforcement scheme of multiple groups of whole piles is established, and the scheme with the lowest steel consumption is selected under the requirements of uplift resistance, crack and damage control. The application solves the problem of disconnection between local optimization and overall analysis, improves the uplift resistance and crack control capacity of the pile body, and reduces the material consumption.

Description

Technical Field

[0001] This invention relates to the field of structural engineering design and optimization technology, specifically to an optimization method for prestressed square pile structures based on damage identification and boundary adjustment. Background Technology

[0002] Prestressed concrete irregular square piles are a commonly used type of foundation bearing component, characterized by high cross-sectional utilization, good bearing capacity, strong construction adaptability, and convenient connection with pile caps. They have been widely used in high-rise buildings, bridge engineering, soft soil foundation treatment, and uplift foundations. Compared with piles with uniform cross-sections, prestressed irregular square piles typically have geometric features such as large-to-small variable cross-sections, concave-to-convex profiles, lifting ring grooves, and local connection structures. Their stress state is more complex, and stress concentration and damage accumulation are more likely to occur in local areas.

[0003] As pile foundation engineering develops towards higher loads, higher reliability, and higher economy, the pull-out resistance, crack control, and material utilization efficiency of prestressed irregular square piles are receiving more attention. In the process of pile structure optimization, how to quickly identify weak areas in the pile body and make structural improvements accordingly, while ensuring that a complete finite element analysis of the pile body can still be conducted after local structural modifications, is a crucial issue that needs to be addressed in the design and structural optimization of prestressed irregular square pile products.

[0004] Existing pile structure design and optimization methods have the following main shortcomings:

[0005] First, traditional empirical design methods mainly rely on empirical formulas and homogenization assumptions, which do not adequately consider the damage evolution laws of complex local structures such as the large-to-small cross-section transition zone and the root of the lifting ring groove in irregularly shaped piles, making it difficult to accurately identify weak areas in the pile body. If local reinforcement is carried out solely based on experience, it is easy to cause over-reinforcement or under-reinforcement, affecting structural safety and material economy.

[0006] Secondly, conventional finite element simulation methods are mostly used for design verification, which usually requires stress analysis after a complete 3D model has been established. When the simulation results show that the local structure does not meet the requirements, it is necessary to modify the geometric model, re-mesh, and reorganize the finite element analysis file, resulting in a large workload and low optimization efficiency in multiple rounds of optimization.

[0007] Third, while existing parametric optimization methods can improve the efficiency of local structural modifications, in integral load-bearing components such as prestressed irregular square piles, the remaining pile models often struggle to automatically follow changes in the connection boundaries after the size or shape of locally weak areas changes. If the local model cannot maintain continuous connection with the remaining pile models, it will lead to problems such as boundary discontinuities, incomplete force transfer, or mesh distortion in the overall finite element analysis, affecting the accuracy of simulation results and the continuity of the optimization process.

[0008] Fourth, for prestressed irregular square piles, the pile body usually adopts a uniform reinforcement form along the length direction. Reinforcement optimization should not be simply understood as adjusting the reinforcement at different length positions. Instead, it should be based on the results of local structural optimization, comparing and selecting the uniform reinforcement scheme of the whole pile, and reducing the amount of steel used while meeting the requirements of pull-out bearing capacity, crack control and damage control.

[0009] Therefore, it is necessary to propose a method for optimizing the structure of prestressed irregular square piles. This method identifies weak areas through damage identification, improves the structure through local parametric optimization, and ensures that the overall pile model after local modification can still be continuously stressed and stably calculated by synchronously adjusting the connection boundary. This improves the efficiency of pile structure optimization and the reliability of optimization results. Summary of the Invention

[0010] To address the problems in existing prestressed irregular square pile structure optimization, such as insufficiently intuitive identification of weak areas, easy disconnect between local structural optimization and overall finite element analysis, difficulty in synchronously adjusting other pile models after changes in local parameters, and difficulty in balancing performance and steel consumption in the overall pile reinforcement scheme, this invention proposes a prestressed square pile structure optimization method based on damage identification and boundary adjustment.

[0011] This invention establishes an initial finite element model of the pile body and extracts concrete damage factors to identify weak areas in the pile body. For these weak areas, a parametric model of the pile body with modifiable structural dimensions is established. When the structural parameters of the weak areas change, the node positions or mesh positions of the remaining pile body models near the connection boundaries are adjusted synchronously based on the changes in the coordinates of the connecting boundary nodes, ensuring that the updated overall pile body model maintains continuous connection and complete force transmission. Based on this, finite element analysis is performed on the updated overall pile body model, and the final optimization result is obtained by comparing and selecting a unified reinforcement scheme for the entire pile.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] A prestressed square pile structure optimization method based on damage identification and boundary adjustment includes the following steps:

[0014] S1: Establish the initial finite element model of the prestressed irregular square pile body, and conduct simulation analysis on the stress response and damage evolution process of the pile body under axial tensile load to obtain the initial damage simulation results.

[0015] S2: Extract the concrete damage factor D based on the initial damage simulation results, and identify the areas where the damage factor D is greater than 0.5 as the weak areas of the pile body; design a structural improvement scheme for the weak areas of the pile body, and convert the structural improvement scheme that meets the requirements of pull-out performance, crack control and manufacturing process into a parameterized model of the pile body; the parameterized model of the pile body sets the structural dimensions that need to be adjusted in the weak areas of the pile body as modifiable parameters.

[0016] S3: Generate an overall pile model for finite element analysis based on the parameterized pile model, and divide the overall pile model into a local pile model to be optimized and other pile models; wherein, the local pile model to be optimized corresponds to the weak area of ​​the pile, and the other pile models correspond to the pile parts other than the weak area of ​​the pile.

[0017] S4: Establish connection constraints at the dividing boundary between the local pile body model to be optimized and the other pile body models to ensure continuous stress in the finite element analysis; when the structural parameters of the local pile body model to be optimized change, extract the coordinates of the connection boundary nodes before and after the update, calculate the change in the position of the connection boundary, and adjust the node positions or mesh positions of the other pile body models near the connection boundary according to the change in the position of the connection boundary, so that the other pile body models are re-aligned with the updated local pile body model to be optimized and maintain continuous connection.

[0018] S5: Perform finite element analysis on the updated overall pile model to determine whether the damage factor, crack control index, and pull-out performance index of the weak area of ​​the pile meet the requirements; if not, continue to adjust the structural parameters of the local pile model to be optimized; if they meet the requirements, obtain the structural optimization results of the weak area.

[0019] S6: Based on the structural optimization results of the weak area, establish multiple sets of alternative schemes for unified reinforcement of the whole pile, and conduct finite element analysis and performance comparison of each alternative scheme; under the premise of meeting the requirements of pull-out bearing capacity, crack control and damage factor control, select the whole pile reinforcement scheme with lower steel consumption to obtain the final optimization result.

[0020] Furthermore, in step S2, the weak area of ​​the pile body includes at least the large-to-small cross-section transition zone, the root of the lifting ring groove, and other local structural areas with a damage factor D greater than 0.5.

[0021] Furthermore, in step S2, the modifiable parameters in the parameterized model of the pile body include at least one of the following: the transition length, radius of the arc, and transition angle of the variable cross-section transition zone; the width, depth, and bottom fillet radius of the lifting ring groove; and the number, diameter, spacing, and arrangement position of the reinforcing ribs.

[0022] Furthermore, in step S4, the connection constraint includes at least one of Tie binding constraint, multi-point constraint MPC, or one-dimensional connection unit capable of transmitting axial force, shear force, and displacement relationship.

[0023] Furthermore, in step S4, the local pile body model to be optimized, the remaining pile body models, the connection constraint file, and the working condition loading file are combined to form an overall pile body optimization analysis model for finite element analysis.

[0024] Further, in step S4, the change in the position of the connection boundary is obtained by extracting the coordinates of the connection boundary nodes before and after the update of the local pile body model to be optimized and calculating the difference between the corresponding node coordinates; when there are multiple connection boundary nodes, the overall change in the position of the connection boundary is obtained by fitting using the least squares method.

[0025] Furthermore, in step S4, after adjusting the node positions or mesh positions of the remaining pile body models near the connection boundary, the updated finite element mesh is subjected to quality checks, and the Jacobian ratio of the updated mesh is made positive.

[0026] Furthermore, in step S6, the reinforcement parameters in the alternative scheme for unified reinforcement of the entire pile include at least one of the following: number of prestressed tendons, diameter of prestressed tendons, arrangement position of prestressed tendons, tension control stress, diameter of stirrups, and spacing of stirrups.

[0027] Furthermore, in step S6, when performing finite element analysis on the alternative schemes for unified reinforcement of the entire pile, the initial crack load, ultimate load, maximum crack width, damage factor distribution and steel consumption corresponding to each alternative scheme are obtained, and these are used as the basis for comparing the reinforcement schemes of the entire pile.

[0028] Beneficial effects:

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] First, this invention enables the quantitative identification of weak areas in the pile body based on damage factors. By performing finite element analysis on the stress response and damage evolution process of prestressed irregular square piles under axial tensile loads, the concrete damage factor D is extracted, and areas with a damage factor D greater than 0.5 are identified as weak areas in the pile body. This allows for a clearer identification of vulnerable parts such as the transition zone between large and small cross sections and the root of the lifting ring groove, providing a basis for subsequent local structural optimization.

[0031] Secondly, this invention can improve the efficiency of structural improvement in weak areas. By setting the structural dimensions that need to be adjusted in the weak areas as modifiable parameters, structural parameters such as the transition length of the variable cross-section transition zone, the radius of the arc, the size of the lifting ring groove, and the arrangement of the reinforcing ribs can be directly adjusted, thereby facilitating the rapid formation of multiple sets of local structural improvement schemes and reducing the amount of repetitive modeling work.

[0032] Third, this invention can solve the problem of disconnect between local structural optimization and overall finite element analysis. This invention divides the overall pile model into a local pile model to be optimized and the remaining pile models, and establishes connection constraints at the boundary between the two. When the structural parameters of the local pile model to be optimized change, the node positions or mesh positions of the remaining pile models near the connection boundary are adjusted synchronously according to the changes in the coordinates of the connection boundary nodes. This ensures that the updated overall pile model maintains continuous connection and complete force transmission, thereby avoiding the problem of the overall model being unable to be analyzed continuously after the local model is modified.

[0033] Fourth, this invention helps maintain the quality and stability of the finite element mesh. By calculating the change in the position of the connection boundary and simultaneously adjusting the node positions or mesh positions of the remaining pile body models near the connection boundary, the risk of misalignment, overlap, gaps, or mesh distortion after local structural modifications can be reduced. At the same time, mesh quality checks ensure that the mesh Jacobian ratio is positive, which helps improve the stability of subsequent nonlinear damage analysis.

[0034] Fifth, this invention balances pile tensile strength and material usage. After obtaining structural optimization results for weak areas, this invention establishes multiple alternative schemes for uniform reinforcement of the entire pile, and comprehensively compares and selects the scheme based on initial crack load, ultimate load, maximum crack width, damage factor distribution, and steel usage. Under the premise of meeting the requirements for tensile bearing capacity, crack control, and damage factor control, selecting the overall pile reinforcement scheme with lower steel usage is beneficial for improving pile tensile strength and crack control capabilities, while reducing material usage. Attached Figure Description

[0035] Figure 1 shows the damage distribution of the irregular square piles before optimization; where: (a) is the damage distribution of piles with a diameter of 350mm-300mm; (b) is the damage distribution of piles with a diameter of 400mm-360mm; and (c) is the damage distribution of piles with a diameter of 450mm-400mm.

[0036] Figure 2 is a schematic diagram of the finite element model of a 350mm-300mm prestressed irregular square pile;

[0037] Figure 3 shows the cross-sectional damage distribution at the groove of the pile body in this invention; wherein, (a) to (c) are the overall damage distribution diagrams of pile types 350mm-300mm, 400mm-360mm, and 450mm-400mm respectively, and (d) to (f) are the local magnified damage distribution diagrams of the corresponding pile types respectively.

[0038] Figure 4 shows a comparison of the load-displacement curves of a specimen; where: (a) is the curve before optimization; (b) is the comparison curve after optimization;

[0039] Figure 5 This is a flowchart of the prestressed square pile structure optimization method based on damage identification and boundary adjustment according to the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only used to illustrate the implementation of the present invention and are not intended to limit the scope of protection of the present invention; without departing from the technical concept of the present invention, those skilled in the art can make adaptive adjustments to the relevant steps and parameters according to different pile types, material parameters and engineering boundary conditions.

[0041] Example 1: An optimization method for prestressed square pile structures based on damage identification and boundary adjustment

[0042] Step 1: Establish the initial finite element model of the pile body and obtain the initial damage simulation results.

[0043] Based on the pile geometry, reinforcement configuration, and boundary conditions of the prestressed irregular square pile, an initial finite element model of the pile body is established, such as... Figure 2 As shown in the figure. The model is used to simulate the stress response and damage evolution process of the pile under axial tensile load, and to obtain the initial damage simulation results.

[0044] Material properties are set as follows: concrete uses the concrete plastic damage model, i.e., the CDP model; prestressing tendons use the ideal elastic-plastic constitutive model. The constraint relationships between the components include: tie-bonding constraint between the connector and the concrete interface, embedded constraint between the steel cage and the concrete, and multi-point constraint, i.e., MPC constraint, between the prestressing tendons and the nuts, to simulate the prestress transfer and the coordinated stress at the connection points.

[0045] Based on the preset axial tensile load and boundary conditions, damage simulation analysis is performed on the initial pile design to obtain the stress distribution, displacement response, and concrete damage factor distribution of the pile during the tensile process. Through the above simulation analysis, initial damage simulation results are obtained for identifying weak areas in the pile.

[0046] Damage simulation analysis is used to obtain the damage distribution of the pile concrete, such as Figure 1 and Figure 3 As shown, the concrete damage factor D of each region is extracted. When the damage factor D of a certain region is greater than 0.5, the region is identified as a weak area of ​​the pile body and is the focus of subsequent structural improvement and parameter optimization.

[0047] Step 2: Weak Area Identification, Structural Improvement, and Parametric Modeling

[0048] The concentrated damage areas of the pile body are identified based on the initial damage simulation results. In this embodiment, the damage of 350mm-300mm piles is mainly concentrated in the large-to-small cross-section transition zone, while the damage of 400mm-360mm and 450mm-400mm piles is mainly concentrated in the lifting ring groove area. It should be understood that the weak areas of the pile body can be determined according to the damage factor distribution of different pile types, and at least include the large-to-small cross-section transition zone, the root of the lifting ring groove, and other local structural areas where damage factors are concentrated.

[0049] Structural improvement schemes were designed to address the aforementioned weak areas. These schemes include at least one of the following: adjusting the radius of the variable cross-section transition zone arc, adjusting the variable cross-section transition length, optimizing the fillet radius of the lifting ring groove, adjusting the groove width and depth, and adding reinforcing ribs. The structural improvement schemes were verified under finite element analysis conditions corresponding to the engineering stress state. When the damage factor D of the improved weak area is reduced to below 0.5, and the requirements for pull-out resistance, crack control, and manufacturing processes are met, the structural improvement scheme is determined to be effective.

[0050] Effective structural improvement schemes are transformed into a parametric model of the pile body. This parametric model refers to a finite element model where the structural dimensions requiring adjustment in the weak areas of the pile body are set as modifiable parameters. These modifiable parameters include at least one of the following: transition length, radius of curvature, and transition angle of the variable cross-section transition zone; groove width, depth, and bottom fillet radius of the lifting ring groove; and the number, diameter, spacing, and placement of reinforcing ribs. These parameters correspond to the geometric dimensions of specific structural parts of the pile body. When any parameter changes, the corresponding local shape of the pile body, connection boundaries, and reinforcement positions are updated synchronously to form a new optimized pile body scheme, which is then used for subsequent finite element analysis.

[0051] Step 3: Optimize the structural parameters of the weak area and obtain the optimization results of the weak area.

[0052] Based on the above-mentioned parametric model of the pile body, an overall pile body model for finite element analysis is generated. In order to complete local structural optimization without repeatedly rebuilding the entire pile body model, the overall pile body model is divided into two parts: one part is the model of the weak area that needs to be adjusted in terms of structural size or shape, and the other part is the remaining pile body model that does not directly participate in the optimization but needs to be connected with the weak area.

[0053] When the radius of the arc, length of the transition section, shape of the lifting ring groove, or size of the reinforcing ribs in the aforementioned weak areas change, the remaining pile body models need to synchronously adjust the connection boundaries according to the changes in the boundary positions of the weak areas. This ensures that the two parts of the model remain continuous, aligned, and have a complete force transfer relationship after the update. This process avoids rebuilding the complete pile body model and re-meshing the overall mesh after each parameter change, thereby improving the efficiency and stability of pile structure optimization.

[0054] S31: Pile Body Model Zoning

[0055] Based on the initial damage simulation results, the overall finite element model of the pile body is divided into a local pile body model to be optimized and the remaining pile body model. The local pile body model to be optimized refers to the local areas of the pile body with large damage factors that require structural improvement, such as the large-to-small cross-section transition zone, the root of the lifting ring groove, and other areas where damage is concentrated. The remaining pile body model refers to the part of the pile body other than the aforementioned local areas to be optimized. This part does not directly change the structural dimensions or shape, but needs to maintain a connection with the local pile body model to be optimized in the finite element analysis.

[0056] The local pile model to be optimized adopts parametric modeling, allowing structural parameters such as the radius of curvature, transition section length, lifting ring groove shape, or stiffener dimensions to be directly adjusted. The remaining pile models can utilize existing solid mesh models to preserve the overall pile length, boundary conditions, constraint relationships, and force transfer paths. This division allows for modification of only the structural parameters of weak areas while maintaining the integrity of the overall pile finite element analysis model.

[0057] S32: Connection and parameter linkage between local piles and other piles

[0058] After partitioning the pile model, the local pile model to be optimized is reconnected to the rest of the pile model at the partition boundaries. This connection can be achieved through Tie binding constraints, multi-point constraint MPC, or one-dimensional connection elements capable of transmitting axial force, shear force, and displacement relationships. By using these connection methods, the local pile model to be optimized and the rest of the pile model remain as a continuous pile under stress in the finite element calculation, avoiding boundary separation, displacement discontinuity, or force transmission interruption caused by model partitioning.

[0059] The aforementioned connection constraint information is saved as a model connection file. Then, using the INCLUDE command in the finite element input file, the local pile model to be optimized, the remaining pile models, the connection file, and the loading condition file are combined into a complete pile optimization analysis model. This allows for individual modification of the structural parameters of weak areas, while also enabling verification of the modified load-bearing performance within the complete pile model.

[0060] Furthermore, to enable the remaining piles to automatically adjust to changes in the dimensions of the local pile to be optimized, boundary adjustment parameters for the remaining piles are set in the model, and a correlation is established between these parameters and the corresponding structural parameters of the local pile to be optimized. When parameters such as the fillet radius, length, groove shape, or reinforcing ribs of the local pile to be optimized change, the position and dimensions of the remaining piles at the connection boundary are updated synchronously, thus ensuring that the two parts of the model can always be correctly connected.

[0061] S33: Local structural updates and synchronous adjustments to the remaining pile boundaries

[0062] The structural parameters of the local pile model to be optimized are read and adjusted according to the optimization objective. These structural parameters include at least one of the following: the radius of the transition zone arc, the length of the transition section, the shape of the lifting ring groove, and the specifications of the reinforcing ribs. When these structural parameters change, the external dimensions and boundary node positions of the local pile model to be optimized change accordingly.

[0063] To ensure that the modified local pile body can still connect correctly with the rest of the pile body, the coordinates of the connection boundary nodes before and after the update of the local pile body model to be optimized are extracted. The positional change of the connection boundary is calculated, and the node positions or mesh positions of the rest of the pile body models near the connection boundary are adjusted accordingly, so that the rest of the pile body models are realigned with the updated local pile body model to be optimized. Through the above processing, problems such as misalignment, overlap, gaps, or discontinuity in connection between the two parts of the model can be avoided.

[0064] In this embodiment, the above-mentioned node coordinate reading, boundary position change calculation, and other pile boundary update operations can be achieved through a secondary development script of the finite element preprocessing software. For example, the HyperMesh secondary development script can be used to complete the automatic update; in other embodiments, other script tools capable of reading node coordinates and updating mesh positions can also be used. After the boundary adjustment is completed, the updated finite element mesh is quality checked to ensure that the mesh Jacobian ratio is positive and meets the calculation requirements of subsequent nonlinear damage analysis.

[0065] Through the above process of local structural update and boundary synchronous adjustment, the optimization results of weak areas are obtained, and the structural parameters are provided for the subsequent comparison of unified reinforcement schemes for the whole pile.

[0066] Step 4: Compare and select unified reinforcement schemes for the entire pile to obtain the final optimized result.

[0067] Based on the structural optimization results of weak areas, a unified reinforcement scheme for the entire prestressed irregular square pile is compared and optimized. Since prestressed irregular square piles usually use a uniform prestressed tendon configuration along the pile length, this step does not adjust the reinforcement at different length positions of the pile, but optimizes the unified reinforcement parameters for the entire pile.

[0068] The unified reinforcement parameters include at least one of the following: number of prestressed tendons, diameter of prestressed tendons, arrangement position of prestressed tendons, tension control stress, diameter of stirrups, and spacing of stirrups. Based on the optimized pile body model of the weak area structure, multiple sets of unified reinforcement alternative schemes for the whole pile are established, and finite element analysis is performed on each scheme to obtain the initial crack load, ultimate load, maximum crack width, damage factor distribution, and steel consumption corresponding to each reinforcement scheme.

[0069] The pull-out performance, crack control, damage factor distribution, and steel consumption of each reinforcement scheme were compared to select the scheme that met the requirements for pull-out bearing capacity, crack control, and damage factor control. Under the premise of meeting the above performance requirements, the monolithic pile reinforcement scheme with lower steel consumption was prioritized as the final optimization result. Figure 4 As shown in the comparison of load-displacement curves before and after optimization, in this embodiment, the load corresponding to a crack width ≤ 0.2 mm is increased after optimization, the initial crack load is increased by about 15% to 25%, and the amount of steel used is reduced by about 5% to 10%.

[0070] The above results demonstrate that this method, through optimization of structural parameters in weak areas and comparison with a unified reinforcement scheme for the entire pile, can improve the pull-out performance and crack control of the pile body while reducing material usage, based on the characteristics of a unified reinforcement structure for prestressed irregular square piles.

Claims

1. A method for optimizing prestressed square pile structures based on damage identification and boundary adjustment, characterized in that, Includes the following steps: S1: Establish the initial finite element model of the prestressed irregular square pile body, and conduct simulation analysis on the stress and damage evolution process of the pile body under axial tensile load to obtain the initial damage simulation results. S2: Extract the concrete damage factor D based on the initial damage simulation results, and identify the areas where the concrete damage factor D is greater than 0.5 as the weak areas of the pile body. A structural improvement scheme was designed for the weak areas of the pile body, and the structural improvement scheme that meets the performance requirements, crack control requirements and manufacturing process requirements was transformed into a parametric model of the pile body. The parameterized model of the pile body sets the structural dimensions that need to be adjusted in the weak areas as modifiable parameters; S3: Based on the parametric model of the pile body, generate an overall pile body model for finite element analysis, and divide the overall pile body model into a local pile body model to be optimized and other pile body models; wherein, the local pile body model to be optimized corresponds to the weak area of ​​the pile body, and the other pile body models correspond to the pile body parts other than the weak area: S4: Establish connection constraints at the dividing boundary between the local pile body model to be optimized and the other pile body models to ensure continuous stress in the finite element analysis; when the structural parameters of the local pile body model to be optimized change, extract the coordinates of the connection boundary nodes before and after the update, calculate the change in the position of the connection boundary, and adjust the node positions or mesh positions of the other pile body models near the connection boundary according to the change in the position of the connection boundary, so that the other pile body models are re-aligned with the updated local pile body model to be optimized and maintain continuous connection; S5: Perform finite element analysis on the updated overall pile model to determine whether the damage factor, crack control index, and pull-out performance index of the weak area meet the requirements; if not, continue to adjust the structural parameters of the local pile model to be optimized; if they meet the requirements, obtain the structural optimization results of the weak area. S6: Based on the structural optimization results of the weak area, establish multiple sets of monopile unified reinforcement alternative schemes, perform finite element analysis and performance comparison on each alternative scheme, and select the monopile reinforcement scheme with lower steel consumption under the premise of meeting the requirements of tensile bearing capacity, crack control and damage factor control, to obtain the final optimization result.

2. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S2, the weak areas of the pile body include at least the large-to-small cross-section transition zone, the root of the lifting ring groove, and other local structural areas with a damage factor D greater than 0.

5.

3. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S2, the modifiable parameters in the parameterized model of the pile body include at least one of the following: the transition length, radius of arc, and transition angle of the variable cross-section transition zone; the width, depth, and bottom fillet radius of the lifting ring groove; and the number, diameter, spacing, and arrangement position of the reinforcing bars.

4. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S4, the connection constraint includes at least one of Tie binding constraint, multi-point constraint MPC, or one-dimensional connection unit capable of transmitting axial force, shear force, and displacement relationship.

5. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S4, the local pile body model to be optimized, the other pile body models, the connection constraint file, and the working condition loading file are combined to form an overall pile body optimization analysis model for finite element analysis.

6. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S4, the change in the position of the connection boundary is obtained by extracting the coordinates of the connection boundary nodes before and after the update of the local pile body model to be optimized and calculating the difference between the corresponding node coordinates; when there are multiple connection boundary nodes, the overall change in the position of the connection boundary is obtained by fitting the least squares method.

7. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S4, after adjusting the node positions or mesh positions of the remaining pile body models near the connection boundary, the updated finite element mesh is quality checked, and the Jacobian ratio of the updated mesh is made positive.

8. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S6, the reinforcement parameters in the alternative scheme for unified reinforcement of the whole pile include at least one of the following: number of prestressed tendons, diameter of prestressed tendons, arrangement position of prestressed tendons, tension control stress, diameter of stirrups, and spacing of stirrups.

9. The method for optimizing prestressed square pile structures based on damage identification and boundary adjustment according to claim 1, characterized in that, In step S6, when performing finite element analysis on the alternative schemes for unified reinforcement of the whole pile, the initial crack load, ultimate load, maximum crack width, damage factor distribution and steel consumption corresponding to each alternative scheme are obtained, and these are used as the basis for comparing the reinforcement schemes of the whole pile.

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