Finite element modeling analysis method and system for micropile compression resistance

Abstract

The present invention provides a finite element modeling and analysis method and system for the compressive resistance of micropiles, which relate to the technical field of civil engineering structure analysis. First, geometric components such as the pile body structural morphology, cross-sectional characteristics, and distribution mode of the micropile are determined. Then, based on the geometric components, a material constitutive relationship covering the description of the mechanical properties of the pile body material and the surrounding medium is established. Then, interaction parameters such as the contact behavior and interface characteristics between the pile body and the surrounding medium are set according to the material constitutive relationship. Then, combined with the interaction parameters, the compressive loading process of the micropile under axial load is simulated and a load application sequence is generated. Finally, based on the load application sequence, the compressive response characteristics of the micropile are analyzed to obtain a compressive performance characterization result, thereby accurately simulating the compressive resistance process of the micropile.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering structure analysis, and in particular to a finite element modeling analysis method and system for micro pile compression resistance. Background Art

[0002] In the field of civil engineering, micropiles, as an important form of foundation reinforcement, are widely used in projects such as building rectification, slope stabilization, and soft soil foundation treatment. Accurately evaluating the compressive performance of micropiles is crucial to ensuring the safety and stability of engineering structures. At present, research on the compressive performance of micropiles mainly relies on field tests and empirical formulas. Although field tests can obtain more realistic data, there are problems such as high test costs, long test cycles, and large restrictions on site conditions, making it difficult to conduct a comprehensive and systematic study of micropiles under different working conditions. Empirical formulas are usually based on some simplified assumptions and limited test data. They cannot accurately consider factors such as the complex geometry of the micropiles, material properties, and the interaction between the pile body and the surrounding medium, resulting in a large deviation between the evaluation results and the actual situation. Summary of the Invention

[0003] In view of the above-mentioned problems, in combination with the first aspect of the present invention, an embodiment of the present invention provides a finite element modeling and analysis method for compressive strength of micropiles, the method comprising:

[0004] Determining geometric elements of the micropile, wherein the geometric elements of the micropile include the pile structure, cross-sectional characteristics, and distribution of the micropile;

[0005] Establishing a constitutive relationship of micropile materials based on the geometric components of the micropile, wherein the constitutive relationship of the micropile materials covers a description of the mechanical properties of the micropile body material and the surrounding medium;

[0006] Setting interaction parameters between the pile body and the surrounding medium according to the constitutive relationship of the micropile material, wherein the interaction parameters between the pile body and the surrounding medium include contact behavior and interface characteristics;

[0007] Simulating the compressive loading process of the micropile under axial load by combining the interaction parameters between the pile body and the surrounding medium to generate a load application sequence;

[0008] The compressive response characteristics of the micropiles are analyzed based on the load application sequence to obtain compressive performance characterization results.

[0009] On the other hand, an embodiment of the present invention also provides a finite element modeling and analysis system for the compressive resistance of micropiles, including a processor and a machine-readable storage medium, wherein the machine-readable storage medium is connected to the processor, the machine-readable storage medium is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the machine-readable storage medium to implement the above method.

[0010] Based on the above aspects, the embodiment of the present invention starts from determining the geometric components of the micropile, comprehensively and accurately defines the pile structure morphology, cross-sectional characteristics and distribution mode of the micropile, and establishes the constitutive relationship of the micropile material based on these geometric components, which can cover the mechanical properties description of the pile material and the surrounding medium in detail, making the model closer to the mechanical behavior of the actual engineering material, and setting the interaction parameters between the pile body and the surrounding medium according to the material constitutive relationship, fully considering the contact behavior and interface characteristics, and accurately simulating the complex interaction between the pile body and the surrounding medium. Combined with these interaction parameters, the compressive loading process of the micropile under axial load is simulated and a load application sequence is generated, which can truly reflect the load application method and change process in the actual project. Finally, based on the load application sequence, the compressive response characteristics of the micropile are analyzed and the compressive performance characterization results are obtained, which effectively improves the accuracy and reliability of the micropile compressive performance evaluation and ensures the safety and stability of the engineering structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the execution flow of the finite element modeling and analysis method for micro pile compression resistance provided by an embodiment of the present invention.

[0012] Figure 2 Schematic diagram of exemplary hardware and software components of a finite element modeling and analysis system for micropile compression resistance provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0013] The present invention will be described in detail below with reference to the accompanying drawings. Figure 1 The figure is a flow chart of a finite element modeling and analysis method for the compressive resistance of micropiles provided by an embodiment of the present invention. The finite element modeling and analysis method for the compressive resistance of micropiles is introduced in detail below.

[0014] Step S110: determining geometrical elements of the micropile, wherein the geometrical elements of the micropile include the pile structure, cross-sectional characteristics and distribution of the micropile.

[0015] Micropiles are commonly used as foundation reinforcement and load-bearing components in foundation construction. The interrelated and mutually influential characteristics of a micropile's structural form, cross-sectional characteristics, and distribution determine its mechanical response when subjected to axial loads.

[0016] The pile structure reflects the micropile's specific spatial shape, which may include various combinations of straight and curved segments. These structural forms are designed based on actual project requirements and geological conditions. Different structural forms can lead to different load transfer paths and distribution within the pile. For example, a pile with curved transition sections may cause stress concentration in specific areas, affecting the pile's load-bearing capacity and durability.

[0017] Cross-sectional characteristics describe the cross-section of a pile at various locations, including the cross-sectional shape and size distribution. Common cross-sectional shapes include circular and polygonal, while the cross-sectional size distribution can be uniform or gradually distributed along the length of the pile. Different cross-sectional characteristics affect the pile's moment of inertia, cross-sectional area, and contact area with the surrounding medium, thereby affecting the pile's mechanical properties, such as compressive and flexural strength.

[0018] The distribution pattern describes the arrangement of micropiles within the foundation. It can be categorized as either a single independent pile or a multi-pile array. In the single independent pile arrangement, each micropile functions independently, with minimal interaction between them. In the multi-pile array arrangement, however, micropiles interact with each other, requiring a predetermined ratio between the center-to-center spacing of adjacent piles and their diameters to ensure they work together and share the load.

[0019] Step S111: identifying the pile structure of the micropile, wherein the pile structure includes a combination of a straight-line structure segment and a curved transition segment.

[0020] In actual engineering, the micropile structure is not a simple, regular shape, but rather a combination of straight segments and curved transition sections. This combination is designed to adapt to varying geological conditions and engineering requirements. For example, when encountering complex soil layers or needing to avoid underground obstacles, a pile designed with a curved transition section can better perform its load-bearing function. The key to identifying the pile structure lies in extracting useful information from the design drawing data and classifying it into straight and curved sections using the following analysis method.

[0021] Step S1111: collecting design drawing data of the micropile, wherein the design drawing data includes two-dimensional or three-dimensional coordinate information of the pile axis.

[0022] Micropile design drawings are crucial for recording detailed geometric information. During project implementation, the design team will design a micropile solution that meets the requirements based on factors such as the engineering geological survey report and the superstructure load requirements. These drawings are then presented on the design drawings. These drawings typically include the two-dimensional or three-dimensional coordinates of the pile axis, depicting the pile's position and orientation in space.

[0023] When collecting design drawing data, you must first communicate effectively with the design company and obtain complete design drawing files. These design drawing files may exist in different formats, such as CAD and PDF. For CAD drawings, professional CAD software can be used to open and view them to accurately extract the required coordinate information.

[0024] To ensure data integrity and accuracy, the design drawings must be carefully reviewed. Check that the markings on the drawings are clear and accurate, that the coordinate information is complete, and that there are no omissions or errors. If any issues are found, promptly communicate and confirm with the design company, and make necessary corrections and additions.

[0025] In some cases, it may be necessary to verify and supplement the design drawing data with on-site measurement data. On-site measurements can be performed using measuring equipment such as total stations and GPS to obtain the actual position and geometric dimensions of the pile. Comparing and analyzing the on-site measurement data with the design drawing data can identify any deviations and enable appropriate adjustments.

[0026] Step S1112: extracting a coordinate point sequence of the pile axis from the design drawing data, wherein the coordinate point sequence is composed of coordinate points evenly distributed along the length direction of the pile.

[0027] After collecting the design drawing data, it needs to be further processed to extract the coordinate point sequence of the pile axis. This coordinate point sequence is the basis for subsequent analysis of the pile structure morphology and is composed of coordinate points evenly distributed along the length of the pile.

[0028] First, the pile axis in the design drawing needs to be identified and located. In CAD software, this can be separated from the drawing using line selection tools or conventional recognition algorithms. The pile axis can then be determined based on the starting and ending points of the axis.

[0029] To obtain evenly distributed coordinate points, the spacing between them must be determined based on the length of the pile and the required number of coordinate points. For example, an interpolation algorithm can be used to generate coordinate points at predetermined intervals along the pile axis. The choice of interpolation algorithm depends on the characteristics of the data and the accuracy required. For example, linear interpolation can be used for smoothly varying coordinate data; however, more complex variations may require a more advanced interpolation algorithm, such as spline interpolation.

[0030] When generating a coordinate point sequence, it's important to consider the number and distribution of coordinate points. Too few points can lead to information loss and an inability to accurately reflect the pile's structural form. Excessive numbers, on the other hand, increase the workload and complexity of data processing. Therefore, a reasonable selection should be made based on the actual situation.

[0031] After generating the coordinate point sequence, you need to perform a quality check. Check whether the coordinate points are evenly distributed along the length of the pile, whether the coordinate values ​​are consistent with the actual situation, and whether there are any abnormal or erroneous values. If any problems are found, you need to readjust the interpolation algorithm or parameters and regenerate and check again.

[0032] Step S1113: Calculate the slope of the line between adjacent coordinate points in the coordinate point sequence, and divide the line into a straight line segment and a curved transition segment according to the change of the line slope. The straight line segment is a set of continuous coordinate points with a constant line slope, and the curved transition segment is a set of continuous coordinate points with a changing line slope.

[0033] After obtaining the coordinate point sequence of the pile axis, the type of pile structure is determined by calculating the slope of the line connecting adjacent coordinate points. The slope of the line reflects the change in direction between adjacent coordinate points and is a key indicator for distinguishing between straight structural segments and curved transition segments.

[0034] When calculating the slope of a line, for each pair of adjacent points, the coordinate values ​​of the points are used. For example, if two adjacent points are point A (x1, y1, z1) and point B (x2, y2, z2), the slope of the line can be calculated by calculating the difference between the two points on each axis. In a two-dimensional plane, the slope of a line can be expressed as (y2-y1) / (x2-x1). In three-dimensional space, the slope components must be calculated separately for different planes.

[0035] During the calculation process, it is important to pay attention to the consistency of the coordinate system and the accuracy of the slope calculation. Ensure that all coordinate points use the same coordinate system to avoid errors caused by coordinate system conversion. At the same time, for the slope calculation results, appropriate rounding and precision control are required to avoid misjudgment due to calculation errors.

[0036] Based on the change in the slope of the connecting line, the pile structure can be divided into straight segments and curved transition segments. If the slope of the line connecting adjacent coordinate points remains constant, the segment formed by these coordinate points is a straight segment; if the slope of the line changes, this segment is a curved transition segment. During the classification process, it is necessary to set a reasonable slope change threshold to accurately distinguish different structural segments.

[0037] When setting the slope change threshold, factors such as measurement error, data accuracy, and the allowable deviation in actual projects need to be considered. Slope changes that are small and within the set tolerance range can be considered a straight-line segment; however, slope changes that are large and outside the tolerance range are considered a curved transition segment. In practice, an appropriate threshold range can be determined through multiple trials and analysis.

[0038] After demarcating the straight structural segments and curved transition segments, the results need to be verified and adjusted. For example, visualization tools can be used to compare the demarcation results with the original pile axis to verify the validity of the demarcation. If deviations are found in the demarcation results, the slope change threshold needs to be readjusted or further analysis and processing is required.

[0039] Step S1114: for the curved transition section, calculate the tangent angle of the line connecting adjacent coordinate points, and determine the bending direction of the curved transition section based on the rate of change of the tangent angle, wherein the bending direction is clockwise or counterclockwise.

[0040] For the identified curved transition section, its curvature direction needs to be determined. This determination is crucial for analyzing the deformation and stress distribution of the pile under load. This is accomplished by calculating the angle between the tangents of the lines connecting adjacent coordinate points.

[0041] First, for each pair of adjacent coordinate points in the curved transition segment, determine the tangent direction. This can be obtained by calculating the direction of the vector connecting the lines. In a two-dimensional plane, the vector of the connecting line can be expressed as (x² - x¹, y² - y¹); in three-dimensional space, the components along the three coordinate axes must be considered.

[0042] Next, calculate the angle between adjacent tangent lines. You can use the vector angle calculation formula to calculate the tangent angle. During the calculation, pay attention to the direction of the vector and the range of the angle. The angle range is usually between 0 and 180 degrees.

[0043] The curvature direction of a curved transition is determined based on the rate of change of the tangent angle. A positive rate of change indicates a counterclockwise curve; a negative rate of change indicates a clockwise curve. To calculate the rate of change of the tangent angle, the difference between adjacent tangent angles is calculated, and the curvature direction is determined based on the sign of the difference.

[0044] When determining the bend direction, the calculated tangent angle requires multiple verification and analysis. Various calculation methods and tools can be used to ensure the accuracy of the results. The length and curvature of the curved transition segment also need to be considered. For shorter segments or those with less curvature, the bend direction may require more caution.

[0045] Step S1115: Construct a geometric description model of the pile structure morphology based on the length parameters of the straight structure segment, the bending direction of the curved transition segment, and the overall distribution characteristics of the coordinate point sequence. The geometric description model is used to fully characterize the combination of the straight structure segment and the curved transition segment of the micropile.

[0046] After identifying the linear structural segments and curved transition segments and determining the curvature of the curved transition segments, a geometric model describing the pile structure is constructed. This geometric model can fully characterize the combination of the linear structural segments and the curved transition segments of the micropile.

[0047] When constructing a geometric model, you first need to determine the length parameters of straight segments. This can be determined by calculating the distance between adjacent endpoints. When calculating distance, use the coordinate values ​​of the coordinate points to ensure the accuracy of the length parameters.

[0048] For curved transitions, parameters such as curvature and radius need to be determined based on the curvature direction and the distribution characteristics of the coordinate point sequence. A curve fitting algorithm can be used to fit the coordinate points of the curved transition to obtain a mathematical expression for the curve, from which parameters such as curvature and radius can be calculated.

[0049] After determining the characteristic parameters of the straight structural segments and curved transition segments, they are combined according to their actual connection relationship in the pile body. Geometric modeling software such as SolidWorks and ANSYS can be used to splice the straight structural segments and curved transition segments to form a complete pile structure.

[0050] When building the model, pay attention to the connections and transitions between the various structural segments. Ensure smooth transitions between connections, avoiding sharp corners or discontinuities. Also, clearly mark the characteristic parameters of each structural segment in the model, such as the length of straight segments and the bending radius of curved transitions, to facilitate subsequent analysis and processing.

[0051] After constructing the geometric model, it needs to be verified and optimized. This can be done by comparing it with the original design drawings or on-site measurement data to check the model's accuracy and rationality. If any deviations or deficiencies are found in the model, adjustments and optimizations are necessary until it meets the requirements.

[0052] Step S112: extracting the axis direction parameters of the straight-line structural segment and the curvature variation characteristics of the curved transition segment in the pile structure.

[0053] After identifying the micropile structure, the axial direction parameters of the straight structural segment and the curvature variation characteristics of the curved transition segment are further extracted to more accurately describe the geometric characteristics of the pile.

[0054] The axial direction parameters of the straight structural section reflect the direction of the pile body in space, while the curvature change characteristics of the curved transition section reflect the bending degree and change of the pile body.

[0055] For a linear segment, the axis direction vector is calculated by determining its starting and ending coordinates. This axis direction vector accurately represents the direction of the linear segment and can be used for subsequent connection and combination analysis with other segments.

[0056] For curved transitions, we first analyze the distribution of coordinate points to determine the general shape and variation of the curve. Then, using curve fitting methods, we construct a mathematical expression for the curve based on the coordinate points. By taking the derivative of this expression, we obtain the first and second derivatives of the curve, and thus calculate the curvature of the curve at each point. Curvature variation characteristics, including the maximum, minimum, and average values, as well as the variation trend of the curvature over the curve length, can comprehensively describe the geometric characteristics of the curved transition.

[0057] Step S113: determining the overall geometric outline boundary of the micropile based on the axis direction parameters and the curvature variation characteristics, wherein the overall geometric outline boundary is formed by connecting continuous line segments and arcs end to end.

[0058] After obtaining the axial direction parameters of the straight structural segments and the curvature variation characteristics of the curved transition segments, these parameters can be used to determine the overall geometric outline of the micropile. This overall geometric outline, consisting of continuous line segments and arcs connected end to end, accurately describes the external shape of the micropile.

[0059] First, determine the position and direction of the linear segment based on its axis direction parameters. The position of the segment is determined by the coordinates of its start and end points, while its direction is determined by the axis direction vector. During this determination process, ensure the segment's accuracy and consistency with the actual structure.

[0060] For curved transition segments, the shape and position of the arc are determined based on the curvature characteristics. Curve fitting yields a mathematical expression for the curve, along with calculated parameters such as curvature, allowing for precise arc drawing. The arc's position should smoothly connect with adjacent straight segments to ensure continuity of the overall geometric outline.

[0061] Connect the determined line segments and arcs end to end according to their actual connection relationship in the pile body. During the connection process, pay special attention to the treatment of the connection points to ensure smooth connections and avoid sharp corners or discontinuities. You can adjust the coordinates of the connection points and the parameters of the curve to make the connection transition smoother.

[0062] After the connection is complete, the overall geometric outline boundary needs to be checked. Check whether it is closed, that is, whether the starting point and end point coincide. Also check whether it is continuous and whether there are any breakpoints or discontinuities. If any problems are found, make timely adjustments and corrections.

[0063] Finally, to make the overall geometric outline more realistic and improve its accuracy and reliability, it may be necessary to optimize and adjust it. Based on actual needs, the shape and size of the geometric outline can be fine-tuned to better suit engineering requirements.

[0064] Step S114: analyzing the cross-sectional features corresponding to the overall geometric contour boundary, wherein the cross-sectional features include a cross-sectional shape type and a cross-sectional size distribution rule, wherein the cross-sectional shape type is circular or polygonal, and the cross-sectional size distribution rule is a uniform distribution or a gradual distribution along the length direction of the pile body.

[0065] After determining the overall geometric outline of a micropile, analyzing its corresponding cross-sectional characteristics is crucial for gaining a deeper understanding of the pile's mechanical properties. Cross-sectional characteristics, including the cross-sectional shape and size distribution, have a direct impact on the pile's compressive and flexural properties.

[0066] First, the location and orientation of the cross-section must be determined. The cross-section can be located along the length of the pile as needed. Typically, multiple representative locations are selected for analysis to comprehensively understand the cross-sectional characteristics of different parts of the pile. The cross-section orientation is generally perpendicular to the pile axis, but in some special cases, this can be adjusted to meet specific requirements.

[0067] After determining the location and orientation of the section, the coordinates of the intersection of the section and the overall geometric boundary are extracted. These intersection coordinates are key to determining the shape and size of the section. Geometric calculation methods can be used to accurately calculate the intersection coordinates by combining the mathematical expression of the overall geometric boundary with the equation of the section.

[0068] The cross-sectional shape type is determined based on the extracted intersection coordinates. Common cross-sectional shape types include circles and polygons. If the intersection coordinates form a shape close to a circle, the cross-sectional shape type is determined to be circular; if the intersection coordinates form a shape that resembles a polygon, the cross-sectional shape type is determined to be polygonal. During the determination process, parameters such as the figure's perimeter, area, and side length can be calculated and compared with the characteristics of circles and polygons to improve the accuracy of the determination.

[0069] Analyze how the cross-sectional dimensions change along the length of the pile to determine the cross-sectional dimension distribution pattern. Cross-sectional dimensions can be expressed using parameters such as diameter and side length. Calculate the cross-sectional dimensions at different cross-sectional locations and record them. Analysis of this data can determine whether the cross-sectional dimension distribution pattern is uniform or gradually varying along the length of the pile. If the cross-sectional dimensions remain constant at different cross-sectional locations, the cross-sectional dimension distribution pattern is uniform; if the cross-sectional dimensions gradually change along the length of the pile, the cross-sectional dimension distribution pattern is gradually varying.

[0070] To more accurately describe the cross-sectional size distribution, a mathematical expression can be determined. If the cross-sectional size distribution is uniform, a constant can be used to represent the cross-sectional size. If the cross-sectional size distribution is gradual, a linear function, a polynomial function, or other mathematical function can be used to represent the relationship between the cross-sectional size and the pile length. When determining the mathematical expression, a data fitting method can be used to fit the cross-sectional size data at different cross-sectional locations to obtain the most appropriate mathematical expression.

[0071] Step S115: determining the distribution of the micropiles according to the cross-sectional features and the overall geometric contour boundary, wherein the distribution includes a single-pile independent distribution form or a multi-pile array distribution form, wherein the center distance between adjacent pile bodies and the pile body diameter maintain a preset proportional relationship.

[0072] After analyzing the cross-sectional characteristics and overall geometric outline of the micropiles, it is necessary to determine the distribution of the micropiles based on this information. The distribution of micropiles has a significant impact on the bearing capacity and stability of the entire foundation.

[0073] First, evaluate the suitability of the single-pile independent distribution method. This method is suitable for situations where the load is relatively small and the interaction between the piles is not critical. In this configuration, each micropile bears the load independently, and the interaction between them is minimal. Factors such as the foundation load, geological conditions, and the bearing capacity of the piles need to be considered. If the foundation load is relatively dispersed and the geological conditions are relatively uniform, the single-pile independent distribution method may be a suitable option.

[0074] If a single, independent pile arrangement doesn't meet project requirements, consider a multi-pile array arrangement. In this arrangement, multiple micropiles are arranged in a predefined pattern. The center-to-center spacing between adjacent piles is proportional to the pile diameter to ensure they work together and share the load.

[0075] When determining the distribution of a multi-pile array, the number, arrangement, and spacing of the piles should be determined based on factors such as the load size and distribution of the foundation, as well as the geological conditions. Arrangements can vary, from rectangular to triangular, and each has varying effects on the interaction between the piles and the overall load-bearing capacity.

[0076] When determining the center-to-center spacing between adjacent piles, consider the interaction between them. If the spacing is too small, the interaction between the piles will increase, potentially reducing the pile's bearing capacity. If the spacing is too large, the foundation's footprint and cost will increase. Therefore, it's necessary to determine the appropriate preset ratio between the spacing and the pile diameter based on actual conditions through calculation and analysis.

[0077] Once the distribution pattern is determined, it needs to be evaluated and verified. Finite element simulation and other methods can be used to analyze the mechanical properties and load-bearing capacity of micropiles under different distribution patterns to verify whether they meet the project requirements. If not, the distribution pattern needs to be adjusted and optimized until satisfactory results are achieved.

[0078] Step S120: establishing a constitutive relationship of the micropile material based on the geometric components of the micropile, wherein the constitutive relationship of the micropile material covers a description of the mechanical properties of the micropile body material and the surrounding medium.

[0079] After determining the geometrical components of a micropile, establishing the micropile material constitutive relationship is a key step in further analyzing its mechanical properties. This material constitutive relationship describes the mechanical behavior of a material under load, including properties in different stages, such as the elastic, plastic, and damage phases. The material constitutive relationship for a micropile encompasses not only the pile material itself but also the mechanical properties of the surrounding medium, as interactions between the pile and the surrounding medium affect the overall mechanical properties of the micropile.

[0080] Step S121: Acquire the pile material type of the micropile, where the pile material type is concrete or steel.

[0081] The main types of micropiles are concrete and steel. Different materials have different mechanical properties and characteristics, so accurately determining the pile material type is the basis for establishing the material constitutive relationship.

[0082] In actual projects, the type of pile material can be determined by consulting design documents, construction records, and other materials. Design documents usually specify the materials used for micropiles, while construction records can provide detailed information on the materials used in actual construction.

[0083] If accurate information cannot be obtained from the data, it can be confirmed through on-site testing. For example, for concrete materials, a rebound hammer can be used to test the strength of the concrete, and the material type can be inferred by analyzing the strength data. For steel, chemical composition analysis and mechanical property testing can be performed to determine its material and performance.

[0084] Step S122: determining a stress-strain relationship model of the material in the elastic stage according to the pile material type, wherein the stress-strain relationship model includes elastic modulus parameters and Poisson's ratio parameters.

[0085] For a given pile material type, it is necessary to determine its stress-strain relationship model in the elastic stage. In the elastic stage, the stress and strain of the material are linearly related, which can be described by the elastic modulus and Poisson's ratio.

[0086] The elastic modulus is the ratio of stress to strain within a material's elastic range, reflecting its ability to resist elastic deformation. Different materials have different elastic moduli. For example, concrete has a relatively low elastic modulus, while steel has a relatively high elastic modulus. The elastic modulus can be determined through mechanical testing of materials. In this test, a certain stress is applied to the material, the corresponding strain is measured, and the elastic modulus is then calculated based on the ratio of stress to strain.

[0087] Poisson's ratio is the ratio of the absolute values ​​of the transverse normal strain to the axial normal strain when a material is subjected to unidirectional tension or compression. It describes the relationship between the transverse and longitudinal deformations of a material under load. Similarly, Poisson's ratio can also be determined through material mechanics testing. During the test, the transverse and longitudinal strains of the material are measured simultaneously, and the Poisson's ratio is then calculated.

[0088] Based on the measured elastic modulus and Poisson's ratio parameters, a stress-strain relationship model for the material's elastic phase is established. This stress-strain relationship model can be expressed as a mathematical formula, where the corresponding strain value can be calculated by inputting the stress value, and vice versa.

[0089] Step S123: Analyze the plastic deformation characteristics of the pile material under load, and establish the yield criterion and hardening law in the plastic stage. The yield criterion is a yield surface equation based on stress space, and the hardening law is an evolution equation describing the development of the yield surface with plastic strain.

[0090] In order to accurately describe the mechanical behavior of pile materials in the plastic stage, it is necessary to analyze their plastic deformation characteristics under load and establish the corresponding yield criterion and hardening law.

[0091] Step S1231: obtaining plastic strain data of the pile material under different stress states through material mechanics tests, wherein the stress states include uniaxial compressive stress state, biaxial compressive stress state and triaxial compressive stress state.

[0092] Carrying out material mechanics tests is the basis for obtaining plastic strain data of pile materials. First, prepare pile material specimens that meet the test requirements. The size and shape of the specimens must be prepared in accordance with the requirements of relevant standards and test equipment. For unidirectional compressive stress state tests, the specimen is placed on a pressure testing machine, and gradually increasing pressure is applied in one direction. At the same time, displacement sensors and other equipment are used to measure the deformation of the specimen and record the plastic strain data under different pressures. In bidirectional compressive stress state tests, special test equipment is required that can simultaneously apply pressure in two mutually perpendicular directions, and measure the plastic strain under different stress combinations by precisely controlling the size and ratio of the pressure. Triaxial compressive stress state tests are more complicated and require the use of a triaxial testing machine to apply different pressures in three directions of the specimen to simulate a stress state closer to the actual project and collect the corresponding plastic strain data.

[0093] Step S1232: Based on the plastic strain data, a set of yield points corresponding to different plastic strain levels is plotted in a stress space, where the stress space is a three-dimensional space with three principal stresses as coordinate axes.

[0094] After obtaining plastic strain data under different stress states, a three-dimensional stress space is constructed with the three principal stresses as coordinate axes. For each plastic strain level, the corresponding principal stress values ​​are determined based on the experimental data and plotted as coordinate points in the stress space. As the plastic strain level increases, a series of coordinate points are obtained, which constitute the set of yield points corresponding to different plastic strain levels.

[0095] Step S1233: mathematically modeling the yield point set using a surface fitting method to generate a yield surface equation based on stress space, wherein the yield surface equation is a functional relationship expression with respect to the principal stress components.

[0096] To describe the yield boundary represented by the yield point set using a mathematical model, a surface fitting method is employed. First, an appropriate surface fitting function is selected, such as a polynomial function or power function. Then, using a fitting algorithm such as the least squares method, the yield point set plotted in stress space is matched to the selected fitting function. By continuously adjusting the parameters of the fitting function, the error between the fitting function and the yield point set is minimized. The resulting fitting function is the yield surface equation based on stress space, which is a functional relationship between the principal stress components.

[0097] Step S1234: Analyze the parameter variation pattern of the yield surface equation under different plastic strain levels to determine the expansion direction and expansion rate of the yield surface. The expansion direction is the movement trend of the yield surface in the stress space, and the expansion rate is the growth rate of the yield surface size with plastic strain.

[0098] After obtaining the yield surface equation, the parameter variation pattern of the equation at different plastic strain levels is analyzed. As the plastic strain increases, the parameters in the yield surface equation will change accordingly. By comparing the parameter values ​​of the yield surface equation at different plastic strain levels and observing the parameter variation trend, the expansion direction of the yield surface can be determined. The expansion direction of the yield surface indicates the movement trend of the yield surface in stress space, which reflects the direction of change of the yield boundary of the material during plastic deformation. At the same time, the expansion rate of the yield surface is determined by calculating the dimensional change of the yield surface at different plastic strain levels. The expansion rate of the yield surface indicates the growth rate of the yield surface size with plastic strain, which reflects the degree of expansion of the yield boundary of the material during plastic deformation.

[0099] Step S1235: Establish a hardening law based on the expansion direction and expansion rate of the yield surface. The hardening law is an evolution equation with the cumulative plastic strain as the independent variable and the yield surface equation parameters as the dependent variable. The cumulative plastic strain is a combined function of plastic strain components under different stress states.

[0100] Based on the determined expansion direction and expansion rate of the yield surface, a hardening law is established. The cumulative plastic strain is a combined function of the plastic strain components under different stress states, which comprehensively reflects the degree of deformation of the material during the entire plastic deformation process. With the cumulative plastic strain as the independent variable and the yield surface equation parameters as the dependent variable, an evolution equation is established by analyzing the relationship between the two. This evolution equation describes the change law of the yield surface with the development of cumulative plastic strain, that is, the hardening law. In the process of establishing the hardening law, the influence of different stress states on the cumulative plastic strain must be considered to ensure that the hardening law can accurately reflect the plastic deformation behavior of the material in actual engineering.

[0101] Step S124: Identify the surrounding medium type of the micropile, which is soil medium or rock medium.

[0102] The surrounding media types of micropiles are mainly soil and rock. Different surrounding media have different mechanical properties and characteristics, so accurately identifying the surrounding medium type is crucial for establishing the material constitutive relationship.

[0103] The type of surrounding medium can be identified using a geological survey report. This report details the geology of the project site, including the distribution and properties of soil and rock layers. Based on this description, the type of medium surrounding the micropiles can be determined.

[0104] If the geological survey report is not detailed or accurate, further confirmation can be obtained through on-site drilling and testing. Drilling is carried out on-site to obtain rock cores or soil samples. The physical and mechanical properties of the rock cores and soil samples are then tested to analyze their properties and types.

[0105] Step S125: Establish a constitutive model of the medium for the surrounding medium type. The constitutive model of the medium includes elastic parameters, plastic parameters, and damage parameters. The elastic parameters have the same dimension as the elastic modulus parameters of the pile material. The plastic parameters are used to describe the deformation characteristics of the medium after yielding. The damage parameters are used to characterize the degree of internal structural degradation of the medium under load.

[0106] Based on the identified surrounding medium type, a constitutive model of the medium is established. This constitutive model needs to consider the mechanical properties of the medium in the elastic stage, plastic stage, and damage stage.

[0107] During the elastic phase, determine the elastic parameters of the medium. These parameters, which have the same dimension as the elastic modulus of the pile material, reflect the medium's ability to resist deformation within its elastic range. They can be determined through field or laboratory testing. Field testing can employ methods such as static cone penetration and dynamic cone penetration. Laboratory testing involves compression testing of soil or rock samples to measure the stress-strain relationship and calculate the elastic parameters.

[0108] Plastic parameters describe the deformation characteristics of a medium after yielding. When the stress on a medium exceeds its yield strength, it enters the plastic deformation stage. By testing the medium under different stress states, measuring its plastic strain, and analyzing the patterns of plastic deformation, plastic parameters can be determined. Plastic parameters can include yield strength, plastic modulus, and more.

[0109] Damage parameters characterize the degree of internal structural degradation of a medium under load. Under long-term load, the internal structure of a medium gradually becomes damaged, leading to a decrease in mechanical properties. Cyclic loading or fatigue testing can be performed on the medium to observe the progression of damage and measure damage-related parameters such as the damage initiation threshold and damage growth rate.

[0110] Based on the determined elastic parameters, plastic parameters, and damage parameters, a constitutive model of the medium is established. This constitutive model of the medium can be expressed using a mathematical formula. By inputting parameters such as stress and strain, the mechanical response of the medium at different stages can be calculated.

[0111] Step S130: setting interaction parameters between the pile body and the surrounding medium according to the constitutive relationship of the micropile material, wherein the interaction parameters between the pile body and the surrounding medium include contact behavior and interface characteristics.

[0112] After establishing the constitutive relationship for the micropile material, it is necessary to set the interaction parameters between the pile and the surrounding medium based on this relationship. Complex interactions exist between the pile and the surrounding medium, and these interactions affect the mechanical properties and bearing capacity of the micropile. The interaction parameters primarily include contact behavior and interface characteristics. The following details the steps for setting these parameters.

[0113] Step S131: Based on the elastic modulus parameters of the pile material and the elastic parameters of the surrounding medium in the constitutive relationship of the micropile material, determining the contact behavior type between the pile body and the surrounding medium, wherein the contact behavior type is a hard contact type or a flexible contact type.

[0114] The constitutive relationship of micropile materials includes the elastic modulus parameters of the pile material and the elastic parameters of the surrounding medium. These two parameters are important bases for determining the type of contact behavior between the pile and the surrounding medium.

[0115] When the elastic modulus of the pile material is much greater than that of the surrounding medium, the pile deforms relatively little when subjected to force, while the surrounding medium deforms significantly. In this case, the contact between the pile and the surrounding medium typically exhibits a hard contact type. Hard contact means that the contact between the pile and the surrounding medium is relatively rigid, and the pile exerts a strong constraint on the surrounding medium.

[0116] Conversely, when the elastic modulus of the pile material is close to that of the surrounding medium, both the pile and the surrounding medium will deform to a certain extent when subjected to force. In this case, the contact between the pile and the surrounding medium exhibits a flexible contact type. Flexible contact means that the contact between the pile and the surrounding medium has a certain degree of elasticity, and the interaction between the two is relatively gentle.

[0117] By comparing the magnitude relationship between the elastic modulus parameters of the pile material and the elastic parameters of the surrounding medium, the contact behavior type between the pile and the surrounding medium is determined.

[0118] Step S132: according to the contact behavior type, normal contact parameters are set. The normal contact parameters include a normal stiffness coefficient and a normal contact tolerance. The normal stiffness coefficient is determined according to the ratio of the elastic modulus parameters of the pile material and the surrounding medium. The normal contact tolerance is the maximum allowable penetration distance.

[0119] For the determined contact behavior type, normal contact parameters need to be set. Normal contact parameters mainly include normal stiffness coefficient and normal contact tolerance.

[0120] The normal stiffness coefficient reflects the ability of the pile and the surrounding medium to resist deformation in the normal direction. It is closely related to the elastic modulus of the pile material and the surrounding medium. Generally speaking, the normal stiffness coefficient can be determined based on the ratio of the elastic modulus parameters of the pile material and the surrounding medium. When the ratio is large, the normal stiffness coefficient is relatively large, indicating a relatively rigid contact; when the ratio is small, the normal stiffness coefficient is relatively small, indicating a relatively flexible contact.

[0121] The normal contact tolerance is the maximum permissible penetration distance. During actual contact, due to factors such as material deformation and measurement errors, some penetration may occur between the pile and the surrounding medium. The normal contact tolerance setting should take into account the actual project requirements and accuracy. Setting the tolerance too small may lead to unstable calculation results; setting it too large may affect the accuracy of the results.

[0122] Based on the contact behavior type and related elastic modulus parameters, the normal stiffness coefficient and normal contact tolerance should be appropriately set. During the setting process, relevant engineering experience and specifications can be consulted, and adjustments can be made based on numerical simulation and test results.

[0123] Step S133: Analyze the relative sliding trend between the pile body and the surrounding medium, and set tangential contact parameters. The tangential contact parameters include a friction coefficient and a tangential stiffness coefficient. The friction coefficient is determined according to the surface roughness of the pile body and the particle characteristics of the surrounding medium. The tangential stiffness coefficient and the normal stiffness coefficient maintain a preset proportional relationship.

[0124] There is not only normal contact between the pile and the surrounding medium, but also relative sliding. Therefore, it is necessary to analyze the relative sliding trend between the pile and the surrounding medium and set the tangential contact parameters.

[0125] The coefficient of friction describes the friction between a pile and its surrounding medium. It is closely related to the pile surface roughness and the particle characteristics of the surrounding medium. The rougher the pile surface and the coarser the particles in the surrounding medium, the greater the coefficient of friction. The coefficient of friction can be determined through field or laboratory tests. In these tests, a specific tangential force is applied to the pile and the surrounding medium, and the friction force during relative sliding is measured. The coefficient of friction is then calculated.

[0126] The tangential stiffness coefficient describes the mechanical properties of the pile and the surrounding medium in the tangential direction. It maintains a preset proportional relationship with the normal stiffness coefficient. This preset proportional relationship can be determined based on actual engineering experience and numerical simulation results. Generally speaking, the tangential stiffness coefficient is smaller than the normal stiffness coefficient.

[0127] Tangential contact parameters are set based on the relative sliding trend obtained from the analysis and the determined friction coefficient and the proportional relationship between the tangential stiffness coefficient and the normal stiffness coefficient. During the setting process, the actual contact conditions and mechanical properties between the pile and the surrounding medium must be considered to ensure the rationality and accuracy of the parameters.

[0128] Step S134: determining the interface transition region between the pile body and the surrounding medium. The interface transition region is a thin layer region between the pile body surface and the surrounding medium, and its thickness is determined according to the construction process parameters.

[0129] There is an interfacial transition zone between the pile and the surrounding medium. This interfacial transition zone is a thin layer between the pile surface and the surrounding medium. The existence of the interfacial transition zone has a significant impact on the interaction between the pile and the surrounding medium.

[0130] The thickness of the interface transition zone is determined by construction process parameters. Different construction processes can result in different thicknesses in the interface transition zone. For example, during pile construction, if a slurry wall method is used, the slurry will form a layer of mud on the pile surface. The thickness of this mud layer will affect the thickness of the interface transition zone.

[0131] Construction process parameters also include the pile formation method and the contact method between the pile and the surrounding medium. By analyzing these construction process parameters, the approximate thickness of the interface transition zone can be determined. In actual projects, the thickness of the interface transition zone can also be measured through on-site testing methods such as microscopic observation and ultrasonic testing.

[0132] Step S135: Based on the thickness of the interface transition region, interface characteristic parameters are set. The interface characteristic parameters include interface bonding strength and interface damage evolution parameters. The interface bonding strength is used to describe the ability of the interface to resist separation, and the interface damage evolution parameters are used to characterize the degradation law of the bonding performance of the interface during relative deformation.

[0133] Interface characteristic parameters are crucial for accurately modeling the interaction between the pile and the surrounding medium. Based on the thickness of the interface transition zone, a series of experimental and analytical methods are used to set the interface bond strength and interface damage evolution parameters.

[0134] Step S1351: obtaining the ultimate bonding force data corresponding to different interface transition region thicknesses through an interface shear test, wherein the ultimate bonding force data is the maximum shear force value when separation and failure of the interface occur.

[0135] Conducting an interface shear test is a key step in obtaining ultimate adhesion data. Prepare specimens with different thicknesses of the interface transition region. The preparation of the specimens must strictly control the thickness of the interface transition region to ensure that it meets the test requirements. Install the specimen on the interface shear test device, apply gradually increasing shear forces to the pile body and the surrounding medium, and use a force sensor to measure the magnitude of the shear force and a displacement sensor to measure the relative displacement. When the interface separates and breaks, record the maximum shear force value at this time, which is the ultimate adhesion data. In order to improve the accuracy of the data, it is necessary to repeat the test multiple times and perform statistical analysis on the test results.

[0136] Step S1352: Divide the ultimate bonding force data by the interface contact area to calculate the interface bonding strength, where the interface contact area is the product of the pile body perimeter and the thickness of the interface transition region.

[0137] After obtaining the ultimate bond strength data corresponding to different interface transition zone thicknesses, the interface contact area is calculated. The interface contact area is the product of the pile perimeter and the interface transition zone thickness. The interface contact area is calculated by accurately measuring the pile perimeter and the interface transition zone thickness. The ultimate bond strength data is divided by the interface contact area to obtain the interface bond strength.

[0138] Step S1353: Analyze the relationship curve between the thickness of the interface transition region and the interface bonding strength, and determine the linear fitting parameters of the relationship curve. The linear fitting parameters include the slope and the intercept, which are used to characterize the variation trend of the interface bonding strength with the thickness of the interface transition region.

[0139] The interface bonding strength data corresponding to different interface transition zone thicknesses are plotted in a coordinate system to obtain a relationship curve between the interface transition zone thickness and the interface bonding strength. Observe the shape of the relationship curve to determine whether it has linear characteristics. If the relationship curve is approximately a straight line, a linear fitting method is used to determine its linear fitting parameters. The linear fitting parameters include the slope and intercept. The slope represents the rate of change of the interface bonding strength with the interface transition zone thickness, and the intercept represents the estimated value of the interface bonding strength when the interface transition zone thickness is zero. The linear fitting parameters can be used to effectively characterize the changing trend of the interface bonding strength with the interface transition zone thickness.

[0140] Step S1354: Based on the linear fitting parameters of the relationship curve, an initial value of the interface bonding strength is set. The initial value is the interface bonding strength value corresponding to when the thickness of the interface transition region is equal to the design thickness.

[0141] The initial value of the interfacial bond strength is set based on the linear fit parameters of the relationship curve. The design thickness is the thickness of the interface transition zone determined based on actual project requirements. Substituting the design thickness into the linear fit equation, the corresponding interfacial bond strength value is calculated, which is the initial value of the interfacial bond strength.

[0142] Step S1355: obtaining attenuation data of interface bonding strength with relative deformation through an interface cyclic loading test, wherein the relative deformation is a relative displacement value between the pile body and the surrounding medium.

[0143] Conducting an interface cyclic loading test is an important means to obtain data on the attenuation of interface bonding strength with relative deformation. The specimen is installed on the interface cyclic loading test device, and cyclic shear force is applied to the pile body and the surrounding medium, while the relative displacement and interface bonding strength are measured. As the number of cyclic loading increases and the relative deformation increases, the interface bonding strength will gradually decay. The interface bonding strength data under different relative deformations are recorded to obtain the attenuation data of the interface bonding strength with relative deformation. During the test, the frequency, amplitude and number of cycles of loading must be controlled to ensure that the test results can accurately reflect the changing pattern of the interface bonding performance.

[0144] Step S1356: Use an exponential function to fit the attenuation data to generate interface damage evolution parameters, which include a damage initiation threshold, a damage development rate, and a residual strength coefficient. The damage initiation threshold is the relative deformation when the interface bonding strength begins to decay, the damage development rate is the rate of change during the bonding strength decay process, and the residual strength coefficient is the ratio of the bonding strength after the damage stabilizes to the initial bonding strength.

[0145] The acquired attenuation data of interface bonding strength with relative deformation are fitted. The exponential function is selected as the fitting function because the exponential function can better describe the attenuation process of interface bonding strength. The fitting algorithm is used to match the attenuation data with the exponential function, and the parameters of the exponential function are adjusted to minimize the error between the fitting function and the attenuation data. The interface damage evolution parameters are determined by fitting the exponential function. The damage initiation threshold is the relative deformation when the interface bonding strength begins to decay, which indicates the critical condition for damage to begin to appear on the interface. The damage development rate is the rate of change during the bonding strength decay process, which reflects the development speed of interface damage. The residual strength coefficient is the ratio of the bonding strength after damage stabilization to the initial bonding strength, which indicates the remaining bonding capacity of the interface after damage stabilization.

[0146] Step S140: simulating the compressive loading process of the micropile under the axial load by combining the interaction parameters between the pile body and the surrounding medium, and generating a load application sequence.

[0147] After setting the interaction parameters between the pile and the surrounding medium, it is necessary to combine these parameters to simulate the compressive loading process of the micropile under axial load and generate a load application sequence.

[0148] Step S141: determining the loading point of the micropile, where the loading point is the geometric center of the micropile top.

[0149] The loading point of a micropile is typically the geometric center of the pile top. In practical engineering, the load is generally transferred to the pile body through the pile top. Setting the loading point at the geometric center of the pile top can evenly distribute the load on the pile body and avoid localized stress concentration.

[0150] To determine the loading point, the geometric center of the micropile top must be accurately located based on the micropile's geometry and dimensions. This can be done by measuring dimensions such as the pile top diameter or side length, and then calculating the coordinates of the geometric center. In finite element modeling, the exact coordinates of the loading point are entered into the model to ensure that the load is correctly applied to the pile.

[0151] Step S142: Based on the loading action point, a load application mode is set, where the load application mode is a graded incremental loading mode or a continuous monotonic loading mode.

[0152] Based on the determined loading point, set the load application method. Common load application methods include graded incremental loading and continuous monotonic loading.

[0153] The graded incremental loading method divides the total load into several smaller increments, which are applied to the pile at set intervals. This loading method more accurately simulates the gradual increase in load experienced in actual projects, facilitating observation of the pile's mechanical response and deformation at different loading stages. When setting up the graded incremental loading method, you need to determine the number of loading steps, the size of each increment, and the loading interval.

[0154] Continuous monotonic loading involves applying a load to the pile continuously at a constant rate. This method is suitable for situations where rapid results are required and simplifies the calculation process. When setting up continuous monotonic loading, you must specify the loading rate parameter.

[0155] According to the actual project requirements and analysis purposes, select the appropriate load application method and set the corresponding parameters.

[0156] Step S143: determining an initial load value and a load increment step size for the load application method, wherein the initial load value is a zero load state, and the load increment step size is determined according to an expected maximum load value and a preset number of loading steps.

[0157] According to the selected load application method, determine the initial load value and load increment step. The initial load value is usually the zero load state, that is, the pile is not subjected to load at the beginning of loading.

[0158] The load increment step size is determined by the expected maximum load and the preset number of loading steps. The expected maximum load is the maximum load the pile can withstand, estimated based on factors such as engineering design requirements and geological conditions. The preset number of loading steps is the number of loading cycles determined based on factors such as analysis accuracy requirements and computing resources. The load increment step size is calculated by dividing the expected maximum load by the preset number of loading steps.

[0159] When determining the load increment step size, the mechanical properties and deformation characteristics of the pile must be considered. If the load increment step size is too large, the calculation results may be inaccurate and the mechanical response of the pile during loading may not be accurately captured. If the load increment step size is too small, the calculation time and computing resources will be increased.

[0160] Step S144: combining the normal contact parameter and the tangential contact parameter in the interaction parameters between the pile body and the surrounding medium, defining the coupling relationship between the loading point and the pile top in the finite element model to ensure that the load is evenly transferred to the pile body.

[0161] In the finite element model, the normal and tangential contact parameters, which are part of the interaction parameters between the pile and the surrounding medium, are combined to define the coupling relationship between the loading point and the pile top. This coupling relationship ensures that the load is evenly transferred to the pile, avoiding load concentration or uneven load transfer.

[0162] When defining coupling relationships, it's important to consider the impact of normal and tangential contact parameters on load transfer. Normal contact parameters determine the contact stiffness and tolerance between the pile and the surrounding medium in the normal direction, while tangential contact parameters affect the friction and stiffness between the pile and the surrounding medium in the tangential direction. By properly configuring coupling relationships, loads can be transferred to the pile as intended.

[0163] Finite element software can be used to define coupling relationships using related functions. For example, by setting node constraints, contact pairs, or coupling elements, the loading point can be connected to the nodes at the top of the pile to ensure that they work together and achieve uniform load transfer.

[0164] Step S145: According to the load application method, initial load value and load increment step, a loading simulation operation is performed in the finite element analysis software, the load value and loading time information corresponding to each load increment step are recorded, and a load application sequence including the corresponding relationship between the load value and the loading time is generated.

[0165] Perform loading simulation operations in the finite element analysis software, accurately record the relevant information of each load increment, and generate the load application sequence.

[0166] For example, step S1451: creating a load application module in the finite element analysis software, and setting the loading action point as the action position of the load application module.

[0167] Open the finite element analysis software and create a load application module. This module simulates the load application process. Set the previously determined loading point (the geometric center of the micropile top) as the load application module's action point. Ensure the loading point coordinates are accurate so that the load can be accurately applied to the pile.

[0168] Step S1452: Input the load application mode into the load application module. If it is a graded incremental loading mode, set the number of graded loading times and the incremental ratio of each loading. If it is a continuous monotonic loading mode, set the loading rate parameters.

[0169] Enter the load application method in the Load Application module. If you select the step-by-step loading method, you need to set the number of step-by-step loading steps and the incremental ratio for each step. The number of step-by-step loading steps is determined by the preset number of loading steps, and the incremental ratio for each step is calculated based on the load increment step size and the expected maximum load value. If you select the continuous monotonic loading method, you need to set the loading rate parameter. The loading rate parameter indicates the rate at which the load increases over time and directly affects the simulation effect of the loading process.

[0170] Step S1453: inputting the initial load value into the initial condition setting item of the load application module to ensure that the loading simulation is executed starting from the initial load value.

[0171] Enter the initial load value into the Initial Conditions section of the Load Application module. This value is typically zero load, ensuring that the loading simulation begins with the initial load value. When entering the initial load value, pay attention to the accuracy of the value and the consistency of the units to avoid inaccurate simulation results due to input errors.

[0172] Step S1454: According to the load increment step, a solution time step is set in the load application module, and the solution time step is kept in correspondence with the load increment step to ensure that each load increment step corresponds to an independent solution time step.

[0173] The solution time step is set in the load application module based on the load increment step size. The solution time step corresponds to the load increment step size, ensuring that each load increment step corresponds to a separate solution time step. Properly setting the solution time step size is crucial for ensuring the accuracy and stability of simulation results. If the solution time step size is too large, it may cause errors in the simulation results; if the solution time step size is too small, it will increase the computation time and resource consumption.

[0174] Step S1455: Start the solver of the finite element analysis software, perform the loading simulation operation, and extract the current load value and the corresponding loading time information from the solution result file after each solution time step.

[0175] Start the finite element analysis software's solver and begin the loading simulation. After each time step, the software generates a result file. Extract the current load value and the corresponding loading time information from the result file. The current load value indicates the load magnitude applied at that time step, and the loading time information indicates the time at which the load was applied.

[0176] Step S1456: Arrange the extracted load values ​​and loading time information in chronological order to generate a load application sequence in which the load values ​​correspond to the loading times. The load application sequence is stored in the form of a file, where the first column of the file records the loading time information and the second column records the corresponding load values.

[0177] Arrange the extracted load values ​​and loading time information in chronological order to generate a load application sequence with a one-to-one correspondence between load values ​​and loading times. Store this sequence in a file with the loading time information in the first column and the corresponding load values ​​in the second column. When storing this file, choose an appropriate file format, such as text or CSV, to facilitate subsequent data analysis and processing. Also, ensure that the file is properly stored to prevent data loss or corruption.

[0178] Step S150: analyzing the compressive response characteristics of the micropile based on the load application sequence to obtain compressive performance characterization results.

[0179] After generating the load application sequence, the compressive response characteristics of the micropile need to be analyzed based on this sequence to obtain the compressive performance characterization results. The compressive response characteristics of the micropile include the deformation of the pile body, stress distribution, and bearing capacity.

[0180] Step S151: extracting micropile deformation data corresponding to each load value in the load application sequence, wherein the pile deformation data includes pile top settlement and pile body lateral displacement.

[0181] The micropile deformation data corresponding to each load value is extracted from the load application sequence. The pile deformation data mainly includes the pile top settlement and the pile body lateral displacement.

[0182] Pile top settlement refers to the vertical displacement of the pile top relative to its initial position under axial load. It reflects the vertical compression deformation of the pile. The result output function of finite element analysis software can be used to extract the pile top settlement data corresponding to each load increment.

[0183] The lateral displacement of a pile refers to its horizontal displacement, reflecting its deformation under lateral forces. In finite element analysis, monitoring points can be set up at different locations along the pile body, and the lateral displacement at each point under different loads can be recorded. This allows the distribution of the lateral displacement along the length of the pile to be determined.

[0184] Step S152: Analyze the variation trend of the pile top settlement with the load value to generate a load-settlement curve, wherein the abscissa of the load-settlement curve is the load value and the ordinate is the pile top settlement.

[0185] The load-settlement curve is generated by analyzing the variation of pile top settlement with load value. The load-settlement curve is an important tool for studying the compressive performance of micropiles, as it intuitively reflects the settlement of the pile under different loads.

[0186] With the load value as the horizontal coordinate and the pile top settlement as the vertical coordinate, the pile top settlement data corresponding to each load value are plotted in the coordinate system, and then these data points are connected with a smooth curve to obtain the load-settlement curve.

[0187] By observing the load-settlement curve, we can understand the deformation characteristics of the pile. In the initial stage of the curve, the pile top settlement changes linearly with increasing load, indicating that the pile is in the elastic deformation stage. As the load further increases, the slope of the load-settlement curve gradually increases, and the growth rate of the pile top settlement accelerates, indicating that the pile has begun to enter the plastic deformation stage. When the load reaches the set value, the load-settlement curve may show a clear turning point, at which point the pile may fail.

[0188] Step S153: Based on the load-settlement curve, determine the linear stage characteristic points and nonlinear stage characteristic points of the curve, wherein the linear stage characteristic points are the starting points and the ending points of the linear change of the load-settlement relationship, and the nonlinear stage characteristic points are the critical points where the load-settlement relationship deviates from the linear change.

[0189] Based on the generated load-settlement curve, determine the characteristic points of the linear and nonlinear phases of the load-settlement curve. The characteristic points of the linear phase are the starting and ending points of the linear change in the load-settlement relationship. During the linear phase of the curve, the deformation of the pile is primarily elastic, and the stress-strain relationship is linear. By observing the load-settlement curve, find the point where the linear change begins as the starting point of the linear phase, and the point where the linear change ends as the ending point of the linear phase.

[0190] The characteristic point of the nonlinear phase is the critical point where the load-settlement relationship deviates from linearity. When the load exceeds this critical point, the pile enters the nonlinear deformation phase, where the stress-strain relationship no longer follows a linear relationship. The characteristic point of the nonlinear phase can be determined by calculating the slope change rate of the curve and finding the point where the slope change rate increases significantly.

[0191] After determining these characteristic points, the mechanical properties and deformation characteristics of the pile at different stages can be further analyzed. The slope of the linear stage reflects the elastic stiffness of the pile, while the deformation in the nonlinear stage is related to the plastic deformation and failure mechanism of the pile.

[0192] Step S154: extracting the distribution data of the lateral displacement of the pile body along the length direction of the pile body, and generating a lateral displacement distribution curve, wherein the abscissa of the lateral displacement distribution curve is the pile body depth coordinate, and the ordinate is the lateral displacement.

[0193] The distribution data of the pile's lateral displacement along its length is extracted to generate a lateral displacement distribution curve, which can intuitively display the lateral deformation of the pile at different depths.

[0194] In the finite element analysis, monitoring points were set up at different locations along the pile body, and the lateral displacement at each monitoring point was recorded under different loads. These monitoring points were plotted in a coordinate system with their depth coordinates as the abscissa and the corresponding lateral displacement as the ordinate. These data points were then connected with a smooth curve to produce a lateral displacement distribution curve.

[0195] By analyzing the lateral displacement distribution curve, the lateral deformation pattern of the pile can be determined. The shape and slope of the curve reflect the degree and trend of lateral deformation at different locations on the pile. For example, if the curve has a steeper slope near the pile top, this indicates significant lateral deformation at the top. A peak in the middle of the pile may indicate stress concentration or a weak spot in the middle.

[0196] Step S155: Combine the linear stage characteristic points, nonlinear stage characteristic points and lateral displacement distribution curve of the load-settlement curve to generate a compressive performance characterization result including an ultimate load value, a pile deformation mode and a failure characteristic. The ultimate load value is the maximum load value corresponding to the nonlinear stage characteristic point in the load-settlement curve. The pile deformation mode is determined according to the morphological characteristics of the lateral displacement distribution curve. The failure characteristic is determined according to the development state of the plastic parameters and damage parameters in the constitutive relationship of the pile material.

[0197] Combining the characteristic points of the linear and nonlinear phases of the load-settlement curves with the lateral displacement distribution curves, a compressive performance characterization result is generated. This compressive performance characterization result contains important information such as the ultimate load value, pile deformation mode, and failure characteristics.

[0198] The ultimate load value is the maximum load value corresponding to the characteristic point in the nonlinear phase of the load-settlement curve. It represents the maximum load a micropile can withstand and is an important indicator for evaluating the compressive performance of micropiles. By identifying the characteristic point in the nonlinear phase and finding the corresponding load value, the ultimate load value is obtained.

[0199] The pile deformation mode is determined based on the morphological characteristics of the lateral displacement distribution curve. The shape and slope of the lateral displacement distribution curve reflect the degree and trend of lateral deformation at different locations on the pile. Based on the curve's morphological characteristics, it can be determined whether the pile is experiencing overall tilt, localized bending, or some other deformation mode.

[0200] Failure characteristics are determined based on the development of the plastic and damage parameters within the pile material's constitutive relationship. During finite element analysis, the changes in the pile material's plastic strain and damage parameters are recorded. When the plastic strain and damage parameters reach a set threshold, the pile material begins to fail. By analyzing the development of these parameters, the characteristics of the pile failure, such as the location and form of failure, can be determined.

[0201] The ultimate load, pile deformation pattern, and failure characteristics are compiled into compressive performance characterization results. For example, the ultimate load can be used to determine whether the micropile's bearing capacity meets engineering requirements. The pile deformation pattern and failure characteristics can be used to optimize the micropile's design and construction plan, improving its compressive performance and safety.

[0202] Figure 2 A schematic diagram illustrating exemplary hardware and software components of a finite element modeling and analysis system 100 for micropile compression resistance, provided in some embodiments of the present application, that can implement the concepts of the present application. For example, a processor 120 can be used in the finite element modeling and analysis system 100 for micropile compression resistance and perform the functions described in the present application.

[0203] The finite element modeling and analysis system 100 for micropile compression resistance can be a general-purpose server or a special-purpose server, both of which can be used to implement the finite element modeling and analysis method for micropile compression resistance of the present application. Although only one server is shown in this application, for convenience, the functions described in this application can be implemented in a distributed manner on multiple similar platforms to balance the processing load.

[0204] For example, the finite element modeling analysis system 100 for micro pile anti-compression can include a network port 110 connected to a network, one or more processors 120 for executing program instructions, a communication bus 130, and different forms of storage media 140, such as a disk, ROM, or RAM, or any combination thereof. Exemplarily, the finite element modeling analysis system 100 for micro pile anti-compression can also include program instructions stored in ROM, RAM, or other types of non-transitory storage media, or any combination thereof. The method of the present application can be implemented according to these program instructions. The finite element modeling analysis system 100 for micro pile anti-compression also includes an input / output (I / O) interface 150 between the computer and other input / output devices.

[0205] For ease of explanation, only one processor is described in the finite element modeling and analysis system 100 for micro pile compression. However, it should be noted that the finite element modeling and analysis system 100 for micro pile compression in the present application can also include multiple processors, so the steps performed by one processor described in the present application can also be performed jointly or individually by multiple processors. For example, if the processor of the finite element modeling and analysis system 100 for micro pile compression executes step A and step B, it should be understood that step A and step B can also be performed jointly by two different processors or individually in one processor. For example, the first processor executes step A, the second processor executes step B, or the first processor and the second processor execute steps A and B together.

[0206] In addition, an embodiment of the present invention further provides a readable storage medium having computer executable instructions preset therein. When a processor executes the computer executable instructions, the above finite element modeling and analysis method for the compressive resistance of micropiles is implemented.

[0207] It should be noted that in order to simplify the description of the present invention and thus help understand one or more embodiments of the invention, in the foregoing description of the embodiments of the present invention, multiple features are sometimes combined into one embodiment, figure or description thereof.

Claims

1. A finite element modeling and analysis method for micropile compression resistance, characterized in that: The method comprises: Determining geometric elements of the micropile, wherein the geometric elements of the micropile include the pile structure, cross-sectional characteristics, and distribution of the micropile; Establishing a constitutive relationship of micropile materials based on the geometric components of the micropile, wherein the constitutive relationship of the micropile materials covers a description of the mechanical properties of the micropile body material and the surrounding medium; Setting interaction parameters between the pile body and the surrounding medium according to the constitutive relationship of the micropile material, wherein the interaction parameters between the pile body and the surrounding medium include contact behavior and interface characteristics; Simulating the compressive loading process of the micropile under axial load by combining the interaction parameters between the pile body and the surrounding medium to generate a load application sequence; Analyzing the compressive response characteristics of the micropile based on the load application sequence to obtain compressive performance characterization results; The method of establishing a micropile material constitutive relationship based on the micropile geometric components includes: Acquire a pile material type of the micropile, where the pile material type is concrete or steel; Determining a stress-strain relationship model of the material in the elastic stage according to the pile material type, wherein the stress-strain relationship model includes an elastic modulus parameter and a Poisson's ratio parameter; Analyze the plastic deformation characteristics of the pile material under load, and establish a yield criterion and hardening law in the plastic stage, wherein the yield criterion is a yield surface equation based on stress space, and the hardening law is an evolution equation describing the development of the yield surface with plastic strain; Identifying the type of surrounding medium of the micropile, wherein the surrounding medium type is soil medium or rock medium; A constitutive model of the medium is established for the surrounding medium type. The constitutive model of the medium includes elastic parameters, plastic parameters and damage parameters. The elastic parameters have the same dimension as the elastic modulus parameters of the pile material. The plastic parameters are used to describe the deformation characteristics of the medium after yielding. The damage parameters are used to characterize the degree of internal structural degradation of the medium under load.

2. The finite element modeling analysis method for micropile compression according to claim 1, characterized in that: Determining the geometric elements of the micropile includes: Identifying a pile structure of the micropile, wherein the pile structure comprises a combination of a straight-line structure segment and a curved transition segment; Extracting the axis direction parameters of the straight-line structural segment and the curvature variation characteristics of the curved transition segment in the pile structure; Determining the overall geometric outline boundary of the micropile based on the axis direction parameter and the curvature change characteristic, wherein the overall geometric outline boundary is formed by connecting continuous line segments and arcs end to end; Analyzing cross-sectional features corresponding to the overall geometric contour boundary, the cross-sectional features include a cross-sectional shape type and a cross-sectional size distribution pattern, the cross-sectional shape type being circular or polygonal, and the cross-sectional size distribution pattern being a uniform distribution or a gradual distribution along the length direction of the pile body; The distribution mode of the micropiles is determined based on the cross-sectional features and the overall geometric contour boundary. The distribution mode includes a single pile independent distribution mode or a multi-pile array distribution mode. In the multi-pile array distribution mode, the center distance between adjacent pile bodies maintains a preset proportional relationship with the pile body diameter.

3. The finite element modeling analysis method for micropile compression according to claim 2, characterized in that: The identification of the micropile structure comprises: Collecting design drawing data of the micropile, wherein the design drawing data includes two-dimensional or three-dimensional coordinate information of the pile axis; Extracting a coordinate point sequence of the pile body axis from the design drawing data, wherein the coordinate point sequence is composed of coordinate points evenly distributed along the length direction of the pile body; Calculating the slope of a line connecting adjacent coordinate points in the coordinate point sequence, and dividing the line into a straight-line structure segment and a curved transition segment according to a change in the line slope, wherein the straight-line structure segment is a set of continuous coordinate points whose line slope remains constant, and the curved transition segment is a set of continuous coordinate points whose line slope changes; For the curved transition section, calculating the tangent angle of the line connecting adjacent coordinate points, and determining the bending direction of the curved transition section based on the rate of change of the tangent angle, wherein the bending direction is clockwise or counterclockwise; According to the length parameters of the straight structural segments, the bending directions of the curved transition segments, and the overall distribution characteristics of the coordinate point sequence, a geometric description model of the pile structure morphology is constructed. The geometric description model is used to fully characterize the combination of the straight structural segments and the curved transition segments of the micropile.

4. The finite element modeling analysis method for micropile compression resistance according to claim 1, characterized in that: The analysis of the plastic deformation characteristics of the pile material under load and the establishment of the yield criterion and hardening law in the plastic stage include: Obtaining plastic strain data of the pile material under different stress states through material mechanics tests, wherein the stress states include uniaxial compressive stress state, biaxial compressive stress state, and triaxial compressive stress state; Based on the plastic strain data, plotting a set of yield points corresponding to different plastic strain levels in a stress space, wherein the stress space is a three-dimensional space with three principal stresses as coordinate axes; A surface fitting method is used to mathematically model the yield point set to generate a yield surface equation based on stress space, wherein the yield surface equation is a functional relationship between the principal stress components; Analyze the parameter variation of the yield surface equation under different plastic strain levels to determine the expansion direction and expansion rate of the yield surface. The expansion direction is the movement trend of the yield surface in stress space, and the expansion rate is the growth rate of the yield surface size with plastic strain. According to the expansion direction and expansion rate of the yield surface, a hardening law is established. The hardening law is an evolution equation with cumulative plastic strain as the independent variable and yield surface equation parameters as the dependent variable. The cumulative plastic strain is a combined function of plastic strain components under different stress states.

5. The finite element modeling analysis method for micropile compression resistance according to claim 1, characterized in that: The interaction parameters between the pile body and the surrounding medium are set according to the constitutive relationship of the micropile material, including: Determining a contact behavior type between the pile body and the surrounding medium based on an elastic modulus parameter of the pile body material and an elastic parameter of the surrounding medium in the constitutive relationship of the micropile material, wherein the contact behavior type is a hard contact type or a flexible contact type; According to the contact behavior type, normal contact parameters are set. The normal contact parameters include a normal stiffness coefficient and a normal contact tolerance. The normal stiffness coefficient is determined according to the ratio of the elastic modulus parameters of the pile material and the surrounding medium. The normal contact tolerance is the maximum allowable penetration distance. Analyze the relative sliding trend between the pile and the surrounding medium, and set tangential contact parameters. The tangential contact parameters include a friction coefficient and a tangential stiffness coefficient. The friction coefficient is determined based on the surface roughness of the pile and the particle characteristics of the surrounding medium. The tangential stiffness coefficient maintains a preset proportional relationship with the normal stiffness coefficient. Determine the interface transition region between the pile body and the surrounding medium, wherein the interface transition region is a thin layer region between the pile body surface and the surrounding medium, and the thickness of the interface transition region is determined according to the construction process parameters; Based on the thickness of the interface transition zone, interface characteristic parameters are set. The interface characteristic parameters include interface bonding strength and interface damage evolution parameters. The interface bonding strength is used to describe the ability of the interface to resist separation, and the interface damage evolution parameters are used to characterize the degradation law of the bonding performance of the interface during relative deformation.

6. The finite element modeling and analysis method for micropile compression resistance according to claim 5, characterized in that: The setting of interface characteristic parameters based on the thickness of the interface transition region includes: The interface shear test is used to obtain the ultimate bonding strength data corresponding to different interface transition region thicknesses, wherein the ultimate bonding strength data is the maximum shear force value when the interface separates and fails; The interface bond strength is calculated by dividing the ultimate bond strength data by the interface contact area, where the interface contact area is the product of the pile body perimeter and the thickness of the interface transition region; Analyze the relationship curve between the thickness of the interface transition region and the interface bonding strength, and determine the linear fitting parameters of the relationship curve, wherein the linear fitting parameters include a slope and an intercept, which are used to characterize the variation trend of the interface bonding strength with the thickness of the interface transition region; Based on the linear fitting parameters of the relationship curve, an initial value of the interface bonding strength is set, wherein the initial value is a value of the interface bonding strength corresponding to when the thickness of the interface transition region is equal to the designed thickness; Obtaining attenuation data of interface bond strength as a function of relative deformation through an interface cyclic loading test, wherein the relative deformation is the relative displacement value between the pile body and the surrounding medium; An exponential function is used to fit the attenuation data to generate interface damage evolution parameters, which include a damage initiation threshold, a damage development rate, and a residual strength coefficient. The damage initiation threshold is the relative deformation when the interface bonding strength begins to decay. The damage development rate is the rate of change during the bonding strength decay process. The residual strength coefficient is the ratio of the bonding strength after damage stabilization to the initial bonding strength.

7. The finite element modeling and analysis method for micropile compression resistance according to claim 1, characterized in that: The method combines the interaction parameters between the pile body and the surrounding medium to simulate the compressive loading process of the micropile under the axial load and generate a load application sequence, including: Determine the loading point of the micropile, where the loading point is the geometric center of the micropile top; Based on the loading action point, a load application mode is set, wherein the load application mode is a graded incremental loading mode or a continuous monotonic loading mode; Determine an initial load value and a load increment step size for the load application method, wherein the initial load value is a zero load state, and the load increment step size is determined according to an expected maximum load value and a preset number of loading steps; In combination with the normal contact parameter and the tangential contact parameter of the interaction parameters between the pile and the surrounding medium, a coupling relationship between the loading point and the pile top is defined in the finite element model to ensure that the load is evenly transferred to the pile; According to the load application method, initial load value and load increment step, a loading simulation operation is performed in the finite element analysis software, the load value and loading time information corresponding to each load increment step are recorded, and a load application sequence containing the corresponding relationship between load value and loading time is generated.

8. The finite element modeling and analysis method for micropile compression resistance according to claim 1, characterized in that: The compressive response characteristics of the micropile are analyzed based on the load application sequence to obtain compressive performance characterization results, including: Extracting micropile deformation data corresponding to each load value in the load application sequence, wherein the pile deformation data includes pile top settlement and pile body lateral displacement; Analyze the variation trend of the pile top settlement with the load value to generate a load-settlement curve, wherein the abscissa of the load-settlement curve is the load value and the ordinate is the pile top settlement; Based on the load-settlement curve, determining the linear stage characteristic points and nonlinear stage characteristic points of the curve, wherein the linear stage characteristic points are the starting points and ending points where the load-settlement relationship changes linearly, and the nonlinear stage characteristic points are the critical points where the load-settlement relationship deviates from the linear change; Extracting distribution data of the lateral displacement of the pile body along the length direction of the pile body to generate a lateral displacement distribution curve, wherein the abscissa of the lateral displacement distribution curve is the pile body depth coordinate and the ordinate is the lateral displacement; Combined with the linear stage characteristic points, nonlinear stage characteristic points and lateral displacement distribution curve of the load-settlement curve, a compressive performance characterization result including the ultimate load value, pile deformation mode and failure characteristics is generated. The ultimate load value is the maximum load value corresponding to the nonlinear stage characteristic point in the load-settlement curve, the pile deformation mode is determined according to the morphological characteristics of the lateral displacement distribution curve, and the failure characteristics are determined according to the development state of the plastic parameters and damage parameters in the constitutive relationship of the pile material.

9. A finite element modeling and analysis system for micro pile compression resistance, characterized in that: The invention comprises a processor and a memory, wherein the memory is connected to the processor, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to implement the finite element modeling and analysis method for the compressive resistance of micropiles as described in any one of claims 1 to 8.

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