Anchorage interface bond stiffness determination method based on error correction
By employing an error correction algorithm in FLAC3D software to adjust the bond stiffness of the anchorage interface, the problem of relying on user experience and requiring numerous trial and error attempts to determine the bond stiffness of the anchorage interface in existing technologies is solved, thus achieving efficient and accurate calculation of the bond stiffness of the anchorage interface.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA UNIV OF MINING & TECH (BEIJING)
- Filing Date
- 2026-01-20
- Publication Date
- 2026-07-07
AI Technical Summary
In the existing technology, the method for determining the bond stiffness of the anchorage interface relies on user experience, involves many trial and error attempts and is time-consuming, and cannot efficiently and accurately obtain the bond stiffness of the anchorage interface.
An error correction-based method is adopted. A small deformation calculation mode is set in FLAC3D software. Anchor rods are simulated by the Mohr-Coulomb model and pile structure components. The bond stiffness of the anchorage interface is defined and dynamically adjusted by the error correction algorithm until the relative error accuracy of the peak load set by the user is achieved.
It enables efficient and accurate determination of the bond stiffness of the anchorage interface, reduces reliance on user experience, shortens trial and error time, and improves computational efficiency and result accuracy.
Smart Images
Figure CN121959937B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of numerical calculation of tunnel support, specifically involving a method for determining the bond stiffness of the anchorage interface based on error correction. Background Technology
[0002] Rock bolt support plays a crucial role in controlling the surrounding rock of deep roadways. Using anchoring agents, rock bolts are bonded to the surrounding rock, thus binding rock masses with discontinuous surfaces such as joints and fissures into a unified whole. This, in turn, increases the strength and stability of the surrounding rock mass.
[0003] To reveal the mechanism of mechanical transfer between anchor bolts and the surrounding rock mass, researchers in the field of geotechnical engineering widely employ numerical calculations. Based on numerical calculations, researchers can simulate anchor bolts using structural components and install them in rock masses under different working conditions. Based on loading calculations and monitoring data, researchers can analyze the mechanical transfer process between the anchor bolt and the surrounding rock mass under different working conditions, thereby revealing the mechanism of mechanical transfer between the anchor bolt and the surrounding rock mass.
[0004] In the field of numerical calculation for tunnel support, FLAC3D software is widely used due to its ease of use, fast calculation speed, and user-friendly operation. When using FLAC3D, researchers can simulate anchor bolts using pile structure components. This is because pile structure components have cohesion table parameters. Based on these cohesion table parameters, users can define the bond-slip relationship at the anchorage interface between the anchor bolt and the anchoring agent, and then embed this bond-slip relationship into the pile structure component to explore the anchorage performance of anchor bolt support under different working conditions.
[0005] The bond-slip relationship at the anchorage interface between the anchor bolt and the anchoring agent is closely related to the anchor bolt thread structure, the mechanical properties of the anchoring agent, and the mechanical properties of the surrounding rock. Therefore, using linear or nonlinear formulas may not accurately reflect the bond-slip relationship at the anchorage interface under different working conditions. The most direct solution is to input the bond force and bond-slip per unit length at the anchorage interface into a table, and then assign this table data to the cohesion table parameters of the pile structure component. At this point, the pile structure component will call the table data based on the cohesion table parameters, and then perform anchorage performance calculations according to the user-input bond force and bond-slip per unit length at the anchorage interface.
[0006] Because the bond force and bond slip per unit length at the anchorage interface may not follow linear or nonlinear formulas, it is impossible to calculate the anchorage interface bond stiffness using formulas. A common solution is trial and error. However, the anchorage interface bond stiffness can range from zero to infinity, and this vast range can lead to a very large number of trials and errors, severely impacting efficiency. Furthermore, the trial and error method heavily relies on the user's experience. For new users without prior experience, even using the trial and error method may not yield suitable results. Currently, few studies have proposed efficient and effective methods for obtaining the anchorage interface bond stiffness for this specific condition.
[0007] To address the aforementioned problems, this invention proposes a method for determining the bond stiffness of the anchorage interface based on error correction. This invention is of great significance for efficiently and effectively obtaining the bond stiffness of the anchorage interface and conducting anchorage performance analysis of anchor bolt support. Summary of the Invention
[0008] The purpose of this invention is to propose a method for determining the bond stiffness of the anchorage interface based on error correction. This method overcomes the shortcomings of trial-and-error methods, such as strong dependence on user experience, the large number of trials required, and the long trial-and-error time. Therefore, users can efficiently and effectively obtain the bond stiffness of the anchorage interface when using this invention.
[0009] This invention provides a method for determining the bond stiffness of an anchorage interface based on error correction, comprising the following steps:
[0010] S1: In FLAC3D, set the calculation mode to small deformation calculation mode; generate a 3D numerical mesh and divide the mesh into element volumes;
[0011] S2: Set the three-dimensional numerical mesh constitutive model to the Mohr-Coulomb model and assign material parameters to the unit cells, including Young's modulus, Poisson's ratio, cohesion, internal friction angle and tensile strength.
[0012] S3: Set boundary conditions for the three-dimensional numerical grid, specifically, the boundary surface perpendicular to the load direction of the anchor bolt and close to the load end of the anchor bolt is a roller support; define the table number, in which the horizontal axis is the amount of bond slip at the anchorage interface and the vertical axis is the bond force per unit length at the anchorage interface;
[0013] S4: Install pile structure components inside a three-dimensional numerical grid to simulate anchor bolts, and define the start point, end point, and number of pile structure components;
[0014] S5: Define the material parameters of the pile structure components, specifically including Poisson's ratio, polar moment of inertia, second moment of inertia of the Y-axis in the reference local coordinate system, second moment of inertia of the Z-axis in the reference local coordinate system, Young's modulus, cross-sectional area, normal stiffness, cohesion table parameters, and anchorage interface bond stiffness.
[0015] The polar moment of inertia is calculated using the following formula: , in the formula It is the polar moment of inertia. Let be the diameter of the anchor bolt; the second moment of inertia along the Y-axis in the reference local coordinate system is calculated using the following formula: , in the formula The second moment of inertia along the Y-axis in the reference local coordinate system is calculated using the following formula: , in the formula The second moment of inertia along the Z-axis in the reference local coordinate system;
[0016] For normal stiffness, set it to zero; for cohesion table parameters, set them to the same value as the table number.
[0017] Define the bond stiffness of the anchorage interface And execute the following formula, , in the formula For anchorage interface bond stiffness, The low threshold for bond stiffness at the anchorage interface; where the low threshold for bond stiffness at the anchorage interface Calculate using the following formula, , in the formula This refers to the peak load on the anchor bolt during a physical experiment. This represents the displacement corresponding to the peak load on the anchor bolt during the physical experiment.
[0018] S6: Apply a constant loading speed to the nodes at the loading end of the pile structure member;
[0019] S7: Record the load and displacement along the loading direction at the node at the loading end of the pile structure component to obtain the simulated anchorage performance curve of the pile structure component;
[0020] S8: Modify the bond stiffness of the anchorage interface, with the following logic:
[0021] Execute the following formula, , in the formula This represents the relative error of the peak load on the anchor bolt. For the peak load of the anchor bolt in the numerical calculation, execute the following formula: , in the formula Let the variable be used; execute the first judgment, the logic structure of which is: the user sets the relative error accuracy of the anchor bolt peak load to be... Determine the variable Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the first judgment result is yes, exit the judgment and end;
[0022] If the first judgment result is negative, execute the first loop;
[0023] The first loop executes the following formula: , in the formula To determine the high threshold for bond stiffness at the anchorage interface, execute the following formula. Calculate the peak load of the anchor bolt; calculate the relative error of the peak load of the anchor bolt. ;
[0024] Execute the second judgment; the logic structure of the second judgment is: determine the absolute value of the relative error of the peak load of the anchor bolt. Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the result of the second judgment is yes, exit the judgment and end;
[0025] If the second judgment result is negative, the third judgment is executed; the logic structure of the third judgment is: judge the relative error of the peak load of the anchor bolt. Is it greater than zero?
[0026] If the third judgment result is negative, execute the following formula. ; Execute the following formula, After continuing the first loop, execute the second condition.
[0027] If the third judgment result is yes, execute the following formula. , in the formula Set as a variable; execute the second loop;
[0028] The second loop executes the following formula: , in the formula As variables; execute the following formula, , in the formula For variables The percentage; execute the following formula, , in the formula For variables The percentage; execute the following formula, ; Utilizing the modified anchorage interface bond stiffness Calculate the peak load of the anchor bolt; calculate the relative error of the peak load of the anchor bolt. ;
[0029] Execute the fourth judgment; the logic structure of the fourth judgment is: determine the absolute value of the relative error of the peak load of the anchor bolt. Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the result of the fourth judgment is yes, exit the judgment and end;
[0030] If the result of the fourth judgment is negative, proceed to the fifth judgment; the logic structure of the fifth judgment is: determine the relative error of the peak load of the anchor bolt. If the result of the fifth judgment is yes, execute the formula. ; Execute formula After continuing the second loop, proceed to the fourth conditional statement.
[0031] If the result of the fifth judgment is negative, execute the formula. ; Execute formula After continuing the second loop, execute the fourth judgment.
[0032] As a further description of the above technical solution:
[0033] When dividing the mesh into units, the number of units along the X-axis, Y-axis and Z-axis directions shall not be less than 10.
[0034] As a further description of the above technical solution:
[0035] When defining table numbers, the table number must be an integer greater than zero.
[0036] As a further description of the above technical solution:
[0037] When defining the number of pile structure components, the number of pile structure components shall not be less than 10.
[0038] As a further description of the above technical solution:
[0039] The loading speed applied at the loading end of the pile structure member is less than or equal to 1 μm / s.
[0040] Beneficial effects
[0041] The main beneficial effects of this invention include:
[0042] (1) A low threshold for the bond stiffness of the anchorage interface is defined and a calculation method for the low threshold for the bond stiffness of the anchorage interface is given. Therefore, this low threshold for the bond stiffness of the anchorage interface reduces the range of values for the bond stiffness of the anchorage interface, avoids the defect of blindly selecting values when users select values for the bond stiffness of the anchorage interface, and encourages users to select values within a smaller range of values for the bond stiffness of the anchorage interface.
[0043] (2) This invention proposes a method for determining the bond stiffness of the anchorage interface based on error correction. Based on this method, users have a clear basis for determining the bond stiffness of the anchorage interface. Regardless of whether the user has experience using FLAC3D software, they can follow the method proposed in this invention to scientifically determine the bond stiffness of the anchorage interface, avoiding the defects of unfounded or repeatedly trial-and-error determination of the bond stiffness, and also avoiding the defect of heavily relying on user experience when determining the bond stiffness of the anchorage interface.
[0044] (3) This invention defines the relative error accuracy of the peak load of the anchor bolt. Therefore, when using this invention to calculate the bond stiffness of the anchorage interface, the user can dynamically correct the bond stiffness of the anchorage interface according to the relative error accuracy of the peak load of the anchor bolt until the bond stiffness of the anchorage interface meets the relative error accuracy of the peak load of the anchor bolt set by the user.
[0045] (4) This invention defines variables. and variables Using variables and variables This clarifies the relative error between the peak anchor load in numerical calculations and the peak anchor load in physical experiments. Based on variables... and variables This invention proposes an algorithm for correcting the bond stiffness of the anchorage interface. Therefore, based on this invention, users can dynamically correct the bond stiffness of the anchorage interface according to the relative error of the anchor peak load. This correction algorithm can quickly and efficiently obtain the anchorage interface bond stiffness that meets the user's requirements. Attached Figure Description
[0046] The accompanying drawings, which constitute a part of this application, are used to provide a further understanding of the invention and do not constitute an undue limitation of the invention. In the drawings:
[0047] Figure 1 This is a flowchart illustrating the method for determining the bonding stiffness of the anchorage interface based on error correction proposed in this invention.
[0048] Figure 2 This is a flowchart illustrating the method for correcting the bonding stiffness of the anchoring interface proposed in this invention.
[0049] Figure 3 This is a comparison chart of anchor bolt anchoring performance curves obtained based on physical experiments and numerical calculations. Detailed Implementation
[0050] This invention provides a method for determining the bond stiffness of the anchorage interface based on error correction, such as... Figure 1 As shown, it includes the following steps:
[0051] S1: In FLAC3D, set the calculation mode to small deformation calculation mode; generate a 3D numerical mesh and divide the mesh into element volumes;
[0052] S2: Set the three-dimensional numerical mesh constitutive model to the Mohr-Coulomb model and assign material parameters to the unit cells, including Young's modulus, Poisson's ratio, cohesion, internal friction angle and tensile strength.
[0053] S3: Set boundary conditions for the three-dimensional numerical grid, specifically, the boundary surface perpendicular to the load direction of the anchor bolt and close to the load end of the anchor bolt is a roller support; define the table number, in which the horizontal axis is the amount of bond slip at the anchorage interface and the vertical axis is the bond force per unit length at the anchorage interface;
[0054] S4: Install pile structure components inside a three-dimensional numerical grid to simulate anchor bolts, and define the start point, end point, and number of pile structure components;
[0055] S5: Define the material parameters of the pile structure components, specifically including Poisson's ratio, polar moment of inertia, second moment of inertia of the Y-axis in the reference local coordinate system, second moment of inertia of the Z-axis in the reference local coordinate system, Young's modulus, cross-sectional area, normal stiffness, cohesion table parameters, and anchorage interface bond stiffness.
[0056] The polar moment of inertia is calculated using the following formula: , in the formula It is the polar moment of inertia. Let be the diameter of the anchor bolt; the second moment of inertia along the Y-axis in the reference local coordinate system is calculated using the following formula: , in the formula The second moment of inertia along the Y-axis in the reference local coordinate system is calculated using the following formula: , in the formula The second moment of inertia along the Z-axis in the reference local coordinate system;
[0057] For normal stiffness, set it to zero; for cohesion table parameters, set them to the same value as the table number.
[0058] Define the bond stiffness of the anchorage interface And execute the following formula, , in the formula For anchorage interface bond stiffness, The low threshold for bond stiffness at the anchorage interface; where the low threshold for bond stiffness at the anchorage interface Calculate using the following formula, , in the formula This refers to the peak load on the anchor bolt during a physical experiment. This represents the displacement corresponding to the peak load on the anchor bolt during the physical experiment.
[0059] S6: Apply a constant loading speed to the nodes at the loading end of the pile structure member;
[0060] S7: Record the load and displacement along the loading direction at the node at the loading end of the pile structure component to obtain the simulated anchorage performance curve of the pile structure component;
[0061] S8: Modify the bond stiffness at the anchorage interface, such as Figure 2 As shown, the logic is as follows:
[0062] Execute the following formula, , in the formula This represents the relative error of the peak load on the anchor bolt. For the peak load of the anchor bolt in the numerical calculation, execute the following formula: , in the formula Let the variable be used; execute the first judgment, the logic structure of which is: the user sets the relative error accuracy of the anchor bolt peak load to be... Determine the variable Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the first judgment result is yes, exit the judgment and end;
[0063] If the first judgment result is negative, execute the first loop;
[0064] The first loop executes the following formula: , in the formula To determine the high threshold for bond stiffness at the anchorage interface, execute the following formula. Calculate the peak load of the anchor bolt; calculate the relative error of the peak load of the anchor bolt. ;
[0065] Execute the second judgment; the logic structure of the second judgment is: determine the absolute value of the relative error of the peak load of the anchor bolt. Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the result of the second judgment is yes, exit the judgment and end;
[0066] If the second judgment result is negative, the third judgment is executed; the logic structure of the third judgment is: judge the relative error of the peak load of the anchor bolt. Is it greater than zero?
[0067] If the third judgment result is negative, execute the following formula. ; Execute the following formula, After continuing the first loop, execute the second condition.
[0068] If the third judgment result is yes, execute the following formula. , in the formula Set as a variable; execute the second loop;
[0069] The second loop executes the following formula: , in the formula As variables; execute the following formula, , in the formula For variables The percentage; execute the following formula, , in the formula For variables The percentage; execute the following formula, ; Utilizing the modified anchorage interface bond stiffness Calculate the peak load of the anchor bolt; calculate the relative error of the peak load of the anchor bolt. ;
[0070] Execute the fourth judgment; the logic structure of the fourth judgment is: determine the absolute value of the relative error of the peak load of the anchor bolt. Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the result of the fourth judgment is yes, exit the judgment and end;
[0071] If the result of the fourth judgment is negative, proceed to the fifth judgment; the logic structure of the fifth judgment is: determine the relative error of the peak load of the anchor bolt. If the result of the fifth judgment is yes, execute the formula. ; Execute formula After continuing the second loop, proceed to the fourth conditional statement.
[0072] If the result of the fifth judgment is negative, execute the formula. ; Execute formula After continuing the second loop, execute the fourth judgment.
[0073] In one specific embodiment:
[0074] When dividing the mesh into units, the number of units along the X-axis, Y-axis and Z-axis directions shall not be less than 10.
[0075] In one specific embodiment:
[0076] When defining table numbers, the table number must be an integer greater than zero.
[0077] In one specific embodiment:
[0078] When defining the number of pile structure components, the number of pile structure components shall not be less than 10.
[0079] In one specific embodiment:
[0080] The loading speed applied at the loading end of the pile structure member is less than or equal to 1 μm / s.
[0081] To verify the effectiveness of this invention, the anchoring performance experiment of the anchor bolt conducted in the literature "Experimental Study on Bearing Performance and Deformation Characteristics of GFRP Anti-buoyancy Anchor Bolt" was used as a case study for numerical calculation and comparative verification. The specific contents are as follows:
[0082] S1: In FLAC3D, set the calculation mode to small deformation calculation mode. Generate a rectangular 3D numerical mesh starting from the origin, with dimensions of 0.4 m, 0.4 m, and 6.5 m along the X, Y, and Z axes, respectively, and the number of elements along the X, Y, and Z axes are 10, 10, and 30, respectively.
[0083] S2: Set the three-dimensional numerical mesh constitutive model to the Mohr-Coulomb model and assign material parameters to the unit cells, specifically Young's modulus of 5 GPa, Poisson's ratio of 0.3, cohesion of 7.6 MPa, internal friction angle of 51°, and tensile strength of 4.1 MPa.
[0084] S3: Set boundary conditions for the 3D numerical mesh, specifically, the mesh surface with Z=6.5 is supported by a roller; define table number 12, in which the horizontal axis represents the bond slip at the anchorage interface, and the horizontal axis data are as follows: 0, 0.0005, 0.001, 0.0015, 0.002, 0.0025, 0.003, 0.0035, 0.004, 0.0045, 0.005, 0.0055, 0.006, 0.0065, 0.007, 0.0075, 0.008, 0.0085. The vertical axis of this table represents the bond force per unit length at the anchorage interface. The data on the vertical axis are as follows: 0, 50615, 77665, 89377, 91428, 87680, 80722, 72252, 63351, 54679, 46611, 39336, 32923, 27363, 22608, 18584, 15208, 12397.
[0085] S4: Install pile structure components inside the three-dimensional numerical grid to simulate anchor bolts. Define the starting point of the pile structure component as (0.2, 0.2, 6.5) and the ending point as (0.2, 0.2, 0). The number of structural components is 50.
[0086] S5: Define the material parameters of the pile structure components, specifically including a Poisson's ratio of 0.3 and a polar moment of inertia of 6.03 cm. 4 The second moment of inertia along the Y-axis in the reference local coordinate system is 3.02 cm. 2 The second moment of inertia along the Z-axis in the reference local coordinate system is 3.02 cm. 2 The Young's modulus is 200 GPa, and the cross-sectional area is 6.16 cm². 2 The normal stiffness is 0, the cohesion table parameter is 12, and the anchorage interface bond stiffness is... It is 30.46 kN / mm.
[0087] S6: Apply a constant loading rate of 1 μm / s to the pile structure member node at coordinates (0.2, 0.2, 6.5).
[0088] S7: Record the load and displacement along the loading direction at the node at the loading end of the pile structure component to obtain the anchorage performance curve of the simulated anchor rod of the pile structure component.
[0089] S8: Modify the bond stiffness of the anchorage interface, with the following logic:
[0090] Peak load of anchor bolt obtained based on numerical calculation The value is 283.8 kN. Calculate the relative error of the peak load on the anchor bolt. The value is -11.3%. Execute the following formula: , in the formula As a variable. Perform the first judgment. Set the relative error accuracy of the anchor bolt peak load. It is 0.5%. Due to the variable Greater than the relative error accuracy of the peak load of the anchor bolt Therefore, the first judgment result is negative, and the first loop is executed. After the first loop is completed, the anchorage interface bond stiffness reaches the high threshold. The bond stiffness at the anchorage interface is 60.92 kN / mm. The peak load of the anchor bolt is 60.92 kN / mm. The relative error of the peak load of the anchor bolt is 314.6 kN. It is -1.6%.
[0091] The second judgment is performed, due to the absolute value of the relative error of the peak load of the anchor bolt. Greater than the relative error accuracy of the peak load of the anchor bolt Therefore, the result of the second judgment is negative, and the third judgment is executed.
[0092] Due to the relative error of the peak load of the anchor bolt Since the result is less than zero, the third judgment is negative, and the following formula is executed. Execute the following formula After executing the first loop, the second condition is determined. At this point, the bond stiffness at the anchorage interface is... The peak load of the anchor bolt is 121.84 kN / mm. The relative error of the peak load of the anchor bolt is 327.4 kN. It is 2.4%. This is due to the absolute value of the relative error of the peak load on the anchor bolt. Greater than the relative error accuracy of the peak load of the anchor bolt Therefore, the result of the second judgment is negative, and the third judgment is executed.
[0093] Due to the relative error of the peak load of the anchor bolt Since the result is greater than zero, the third judgment is correct. Execute the following formula: , in the formula The variable is used. The second loop is executed, and after the second loop completes, the bond stiffness at the anchorage interface is determined. The peak load of the anchor bolt is 85.94 kN / mm. The relative error of the peak load of the anchor bolt is 322.8 kN. It is 0.9%.
[0094] Execute the fourth judgment. Due to the absolute value of the relative error of the peak load of the anchor bolt. Greater than the relative error accuracy of the peak load of the anchor bolt Therefore, the result of the fourth judgment is negative, and the fifth judgment is executed.
[0095] Due to the relative error of the peak load of the anchor bolt The result is greater than zero, therefore the fifth judgment is yes, and the formula is executed. Execute the formula After executing the second loop, the fourth judgment is performed. At this point, the bond stiffness of the anchorage interface is... The peak load of the anchor bolt is 76.96 kN / mm. The relative error of the peak load of the anchor bolt is 320.3 kN. The value is 0.1%. This is due to the relative error of the peak load on the anchor bolt. Less than the relative error accuracy of the peak load of the anchor bolt Therefore, the result of the fourth judgment is yes, so the judgment is exited and the process ends.
[0096] Comparing the anchorage performance curves obtained from numerical calculations and physical experiments, such as... Figure 3 As shown, the peak load of the anchor bolt obtained from numerical calculations matches the peak load height of the anchor bolt in the physical experiment, and the relative error of the peak load is within acceptable limits. The error is only 0.1%, significantly smaller than the relative error accuracy of the peak load on the anchor bolt. This demonstrates the accuracy of the numerical calculation results and proves the effectiveness and reliability of the invention. Furthermore, observation of the anchoring performance curve reveals a high degree of agreement between the numerically calculated curve and the physical experimental results, further demonstrating the effectiveness and accuracy of the invention.
[0097] In summary, this process yielded five anchorage interface bond stiffness values when calculating the anchorage interface bond stiffness using this invention: 30.46 kN / mm, 60.92 kN / mm, 121.84 kN / mm, 85.94 kN / mm, and 76.96 kN / mm. The final value of the anchorage interface bond stiffness was 76.96 kN / mm, at which point the numerical calculation result was very close to the physical experimental result. Therefore, for this case, based on numerical calculation, a relatively ideal target value can be obtained after five calculations. However, if a trial-and-error method is used, taking values for the anchorage interface bond stiffness between zero and infinity and trying different values, dozens or even hundreds of calculations may be required to obtain a relatively ideal result. For inexperienced new users, blindly taking values may require even more trial and error. Therefore, compared with the traditional trial-and-error method, this invention has significant advantages.
[0098] This invention is not limited to the preferred embodiments described above. Anyone can derive other forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.
Claims
1. A method for determining the bond stiffness of an anchorage interface based on error correction, characterized in that, Includes the following steps: S1: In FLAC3D, set the calculation mode to small deformation calculation mode; generate a 3D numerical mesh and divide the mesh into element volumes; S2: Set the three-dimensional numerical mesh constitutive model to the Mohr-Coulomb model and assign material parameters to the unit cells, including Young's modulus, Poisson's ratio, cohesion, internal friction angle and tensile strength. S3: Set boundary conditions for the three-dimensional numerical grid, specifically, the boundary surface perpendicular to the load direction of the anchor bolt and close to the load end of the anchor bolt is a roller support; define the table number, in which the horizontal axis is the amount of bond slip at the anchorage interface and the vertical axis is the bond force per unit length at the anchorage interface; S4: Install pile structure components inside a three-dimensional numerical grid to simulate anchor bolts, and define the start point, end point, and number of pile structure components; S5: Define the material parameters of the pile structure components, specifically including Poisson's ratio, polar moment of inertia, second moment of inertia of the Y-axis in the reference local coordinate system, second moment of inertia of the Z-axis in the reference local coordinate system, Young's modulus, cross-sectional area, normal stiffness, cohesion table parameters, and anchorage interface bond stiffness. The polar moment of inertia is calculated using the following formula: , in the formula It is the polar moment of inertia. Let be the diameter of the anchor bolt; the second moment of inertia along the Y-axis in the reference local coordinate system is calculated using the following formula: , in the formula The second moment of inertia along the Y-axis in the reference local coordinate system is calculated using the following formula: , in the formula The second moment of inertia along the Z-axis in the reference local coordinate system; For normal stiffness, set it to zero; for cohesion table parameters, set them to the same value as the table number. Define the bond stiffness of the anchorage interface And execute the following formula, , in the formula For anchorage interface bond stiffness, The low threshold for bond stiffness at the anchorage interface; where the low threshold for bond stiffness at the anchorage interface Calculate using the following formula, , in the formula This refers to the peak load on the anchor bolt during a physical experiment. This represents the displacement corresponding to the peak load on the anchor bolt during the physical experiment. S6: Apply a constant loading speed to the nodes at the loading end of the pile structure member; S7: Record the load and displacement along the loading direction at the node at the loading end of the pile structure component to obtain the simulated anchorage performance curve of the pile structure component; S8: Modify the bond stiffness of the anchorage interface, with the following logic: Execute the following formula, , in the formula This represents the relative error of the peak load on the anchor bolt. For the peak load of the anchor bolt in the numerical calculation, execute the following formula: , in the formula Let the variable be used; execute the first judgment, the logic structure of which is: the user sets the relative error accuracy of the anchor bolt peak load to be... Determine the variable Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the first judgment result is yes, exit the judgment and end; If the first judgment result is negative, execute the first loop; The first loop executes the following formula: , in the formula To determine the high threshold for bond stiffness at the anchorage interface, execute the following formula. ; Calculate the peak load of the anchor bolt; Calculate the relative error of peak load on anchor bolts ; Execute the second judgment; the logic structure of the second judgment is: determine the absolute value of the relative error of the peak load of the anchor bolt. Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the result of the second judgment is yes, exit the judgment and end; If the second judgment result is negative, the third judgment is executed; the logic structure of the third judgment is: judge the relative error of the peak load of the anchor bolt. Is it greater than zero? If the third judgment result is negative, execute the following formula. ; Execute the following formula, After continuing the first loop, execute the second condition. If the third judgment result is yes, execute the following formula. , in the formula Set as a variable; execute the second loop; The second loop executes the following formula: , in the formula As variables; execute the following formula, , in the formula For variables The percentage; execute the following formula, , in the formula For variables The percentage; execute the following formula, ; Utilizing the modified anchorage interface bond stiffness Calculate the peak load of the anchor bolt; Calculate the relative error of peak load on anchor bolts ; Execute the fourth judgment; the logic structure of the fourth judgment is: determine the absolute value of the relative error of the peak load of the anchor bolt. Is it less than or equal to the user-defined relative error accuracy of the anchor bolt peak load? If the result of the fourth judgment is yes, exit the judgment and end; If the result of the fourth judgment is negative, then the fifth judgment is executed; The fifth logical structure is: to determine the relative error of the peak load of the anchor bolt. If the result of the fifth judgment is yes, execute the formula. ; Execute formula After continuing the second loop, proceed to the fourth conditional statement. If the result of the fifth judgment is negative, execute the formula. ; Execute formula After continuing the second loop, execute the fourth judgment.
2. The method for determining the bond stiffness of the anchorage interface based on error correction according to claim 1, characterized in that, When dividing the mesh into units, the number of units along the X-axis, Y-axis and Z-axis directions shall not be less than 10.
3. The method for determining the bond stiffness of the anchorage interface based on error correction according to claim 1, characterized in that, When defining table numbers, the table number must be an integer greater than zero.
4. The method for determining the bond stiffness of the anchorage interface based on error correction according to claim 1, characterized in that, When defining the number of pile structure components, the number of pile structure components shall not be less than 10.
5. The method for determining the bond stiffness of the anchorage interface based on error correction according to claim 1, characterized in that, The loading speed applied at the loading end of the pile structure member is less than or equal to 1 μm / s.