Foundation pit supporting structure mechanical behavior analysis method and system based on step-by-step simulation

Abstract

The invention discloses a foundation pit supporting structure mechanical behavior analysis method and system based on step-by-step simulation, and the method comprises the steps: obtaining geometric data and soil parameters through on-site investigation, constructing a geometric model and a contact surface related soil model, setting material parameters, and simulating soil settlement, upheaval, supporting pile displacement and anchor cable stress step by step. And performing data analysis and outputting a result. According to the invention, through on-site three-dimensional scanning and soil mechanical property sampling, the engineering practice is truly reflected in combination with step-by-step simulation, and the analysis precision is improved; meanwhile, an automatic analysis system is provided, efficient simulation and result output are achieved, and a reliable basis is provided for foundation pit supporting design and construction.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, and more specifically, to a method and system for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation. Background Technology

[0002] Currently, in modern construction engineering, the design and construction of deep foundation pit support structures are crucial for ensuring project safety and stability. Especially under complex geological conditions, effectively controlling soil deformation, settlement, and the stability of the support structure during foundation pit excavation has become a pressing technical challenge.

[0003] Meanwhile, the small-clearance support pile-anchor combination structure, as a flexible support method, is widely used in deep foundation pit engineering, providing reaction force through structural deformation to maintain slope stability. However, due to the diversity of soil properties and the complexity of construction conditions, many shortcomings still exist in actual construction.

[0004] For example, traditional research on deep foundation pit support structures generally focuses on simulations of single working conditions or simple models, rarely considering the impact of complex geological conditions and multi-condition construction processes. Furthermore, during modeling, the soil is often assumed to be an ideal Mohr-Coulomb model, neglecting factors such as groundwater seepage, which may lead to discrepancies between simulation results and actual conditions. In addition, there is still room for improvement in anchor cable layout optimization and prestressing methods, especially under the synergistic effect of multiple rows of anchor cables. The uneven stress distribution of the anchor cables and their stress variations under different working conditions place higher demands on the safety of the support system. Summary of the Invention

[0005] Therefore, this invention provides a method and system for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation, in order to solve the technical problem of insufficient analysis of soil deformation and mechanical behavior in the design and construction of foundation pit support structures in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation includes the following steps:

[0008] S1: Sampling and analysis to obtain data parameters; Three-dimensional scanning of the foundation pit support structure and its surrounding environment is performed to obtain geometric data and material properties, forming three-dimensional scanning data of the foundation pit support structure;

[0009] Simultaneously, soil samples were taken and analyzed in the designated area where the foundation pit support structure and the foundation pit were connected to obtain soil distribution, physical properties, and mechanical parameters.

[0010] S2: Establish a simulation model; Based on the obtained three-dimensional scanning data of the foundation pit support structure, construct a geometric model of the foundation pit support structure, the geometric model including the contact surface associated soil model;

[0011] S3: Set model parameters; Define the material property parameters of the support piles, anchor cables and related components in the model, and set the relevant parameters of the contact surface associated with the soil model;

[0012] S4: Step-by-step simulation; Step-by-step simulation is performed using finite element analysis software;

[0013] The step-by-step simulation includes the simulation of soil settlement at the top of the foundation pit, the simulation of soil heave at the bottom of the foundation pit, the simulation of horizontal displacement of the support piles, and the simulation of axial tensile stress of the anchor cable.

[0014] Set up key monitoring points and record the displacement or stress data of the key monitoring points after each simulation;

[0015] S5: Data Analysis; Based on the data from key monitoring points, perform step-by-step simulation analysis, and output the mechanical behavior analysis results of the foundation pit support structure based on the comparison results of the preset thresholds.

[0016] Based on the above technical solution, the present invention is further described as follows:

[0017] As a further aspect of the present invention

[0018] The geometric model in step S2 also includes a support pile model, an anchor cable model, and related component models;

[0019] The contact surface associated soil model is generated by extending the contact surface between the support pile model, anchor cable model and related component models and the soil on the side and bottom of the foundation pit;

[0020] The outer contour dimensions of the contact surface are set to a×b×c, where a is the length of the side, b is the width of the side, and c is the depth. The outer contour of the soil model associated with the contact surface is a cuboid. Based on the outer contour dimensions of the contact surface, the outer contour cuboid dimensions of the soil model associated with the contact surface are calculated to be A×B×C.

[0021] As a further aspect of the present invention

[0022] The method for calculating the dimensions of the cuboid outer contour of the soil model associated with the contact surface is as follows:

[0023] A=a·α; B=b·α; C=c·β;

[0024] In the formula, α is the horizontal expansion coefficient, which ranges from 2 to 3;

[0025] β is the longitudinal expansion coefficient, which ranges from 1.5 to 2.

[0026] As a further aspect of the present invention

[0027] In step S1, the soil region corresponding to the cuboid region of the outer contour of the soil model associated with the contact surface is used for sampling and analysis.

[0028] The sampling analysis is based on the soil at multiple sampling points in the soil region corresponding to the outer contour cuboid region of the contact surface associated soil model, to obtain basic physical properties, mechanical properties, soil distribution and bearing capacity parameters.

[0029] As a further aspect of the present invention

[0030] In step S3, the parameters of the soil model associated with the contact surface are set based on the soil physical properties, mechanical properties, soil distribution and bearing capacity parameters obtained from the sampling analysis in step S1.

[0031] As a further aspect of the present invention

[0032] In step S4, the specific method for simulating the settlement of the soil at the top of the foundation pit is as follows: a settlement monitoring area is set at the top of the foundation pit, the area is divided into grids, the center point of each grid is a settlement monitoring point, the settlement monitoring points are numbered sequentially, and the settlement value after each simulation is recorded.

[0033] The specific method for simulating soil heave at the bottom of the foundation pit is as follows: a heave monitoring area is set at the bottom of the foundation pit, the area is divided into grids, the center point of each grid is the heave monitoring point, the heave monitoring points are numbered sequentially, and the heave value after each simulation is recorded.

[0034] The specific method for simulating the horizontal displacement of the support pile is as follows: set horizontal displacement monitoring points at different heights of the support pile and record the horizontal displacement value after each simulation.

[0035] The specific method for simulating the axial tensile stress of anchor cables is as follows: set axial tensile stress monitoring points at different locations on the anchor cable and record the axial tensile stress value after each simulation.

[0036] As a further aspect of the present invention

[0037] The settlement values ​​for the simulated soil settlement at the top of the foundation pit are randomly generated between 1 mm and 20 mm; the heave values ​​for the simulated soil heave at the bottom of the foundation pit are randomly generated between 5 mm and 30 mm; the horizontal displacement values ​​for the simulated horizontal displacement of the support piles are randomly generated between 2 mm and 20 mm; and the axial tensile stress values ​​for the simulated axial tensile stress of the anchor cables are randomly generated between 100 kPa and 3000 kPa.

[0038] As a further aspect of the present invention

[0039] In step S5, the maximum allowable values ​​for settlement, heave, horizontal displacement, and axial tensile stress are set. The settlement, heave, horizontal displacement, and axial tensile stress values ​​of each key monitoring point are compared with the corresponding allowable values. If the values ​​exceed the corresponding allowable values, the non-compliance analysis results are output, and simulation parameters are added to the non-compliance analysis results.

[0040] A system for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation, characterized in that,

[0041] The system includes a memory and a computer. The memory stores the analysis program designed using the step-by-step simulation-based mechanical behavior analysis method for foundation pit support structures. The computer is pre-installed with computer-aided design software and finite element analysis software. The computer is communicatively connected to the memory to run the analysis program and, in conjunction with the computer-aided design software and finite element analysis software, automatically analyzes the foundation pit support structure and outputs the step-by-step simulation analysis results, which are then stored in the memory.

[0042] As a further aspect of the present invention, it also includes:

[0043] The display is communicatively connected to a computer, and the computer controls the display to show the step-by-step simulation process and the step-by-step simulation results.

[0044] The present invention has the following beneficial effects:

[0045] This method and system can establish a more accurate profile deformation model of the construction process of small-clearance support structures, and combine it with finite element numerical simulation technology to deeply analyze the settlement and heave patterns of the soil, the horizontal displacement changes of the support piles, and the stress characteristics of the anchor cables during the excavation of the foundation pit. This allows for the proposal of a design scheme that can effectively control the deformation of the foundation pit and improve the safety of the support structure. This research not only helps to improve the theory of deep foundation pit support but also provides important technical guidance for practical engineering, demonstrating significant engineering application value. Attached Figure Description

[0046] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The structures, proportions, sizes, etc., drawn in this specification are only used to complement the content disclosed in the specification, so that those skilled in the art can understand and read them. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0047] Figure 1This is a flowchart illustrating the mechanical behavior analysis method for foundation pit support structures based on step-by-step simulation in an embodiment of the present invention, showing the overall steps from field investigation to data analysis.

[0048] Figure 2 A schematic diagram of the path for obtaining geometric data of the foundation pit support structure and its surrounding environment using 3D scanning;

[0049] Figure 3 A schematic diagram generated for expanding the outer contour dimensions of the soil model associated with the contact surface;

[0050] Figure 4 This is a schematic diagram illustrating the layout of key monitoring points and data recording during the step-by-step simulation process;

[0051] Figure 5 This is a block diagram of the mechanical behavior analysis system for foundation pit support structures based on step-by-step simulation.

[0052] The attached diagram lists the components represented by each number as follows:

[0053] 1. Foundation pit support structure; 2. Support piles; 3. Anchor cables; 4. Contact surface associated soil model; 5. Settlement monitoring points; 6. Heave monitoring points; 7. Horizontal displacement monitoring points; 8. Axial tensile stress monitoring points; 9. Memory; 10. Computer; 11. Monitor. Detailed Implementation

[0054] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] The terms "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Any changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0056] like Figures 1 to 5 As shown, this invention provides a method and system for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation. The specific implementation method is combined with... Figures 1 to 5 The operating principle, operation process, and monitoring and path relationships between various data are explained in detail below.

[0057] In the specific implementation process, such as Figure 2As shown, step S1 obtains the geometric data and material properties of the foundation pit support structure 1 and its surrounding environment; specifically, the foundation pit support structure 1 is scanned in three dimensions using a drone to obtain the geometric shape and spatial distribution of the support piles 2, anchor cables 3 and related components, forming three-dimensional scanning data of the foundation pit support structure 1; at the same time, soil sampling analysis is performed in the set area of ​​the connection between the foundation pit support structure 1 and the foundation pit, and the selected sampling area covers at least the contact surface between the support piles 2 and the soil and the contact surface between the anchor cables 3 and the soil.

[0058] The sampling and analysis process involves multiple sampling points within the corresponding soil region of the cuboid region on the outer contour of the contact surface-associated soil model 4. The number and distribution of sampling points are determined based on the soil homogeneity. After sampling, the soil samples are tested for basic physical properties, mechanical properties, soil distribution, and bearing capacity parameters. These parameters include, but are not limited to, density ρ, internal friction angle φ, cohesion c, compression modulus Es, shear strength, soil layer thickness, soil layer sequence, standard penetration test (SPT) N value, and static cone penetration test (CPT) results. These test results will serve as the foundational data for the subsequent construction of the contact surface-associated soil model 4.

[0059] Next, we proceed to step S2: the simulation model establishment stage. Based on the 3D scanning data of the foundation pit support structure 1 obtained from the on-site survey, a geometric model of the foundation pit support structure 1 is constructed using computer-aided design software. The geometric model includes the support pile model, anchor cable model, and related component models, and simultaneously constructs the contact surface associated soil model 4. The contact surface associated soil model 4 is a cuboid model generated by expanding the contact surfaces between the support piles 2, anchor cables 3, and related components and the soil on the side and bottom of the foundation pit. The calculation method for its outer dimensions is as follows: Figure 3 As shown. Assuming the outer contour dimensions of the contact surface are a×b×c, where a is the length of the side, b is the width, and c is the depth, the outer contour dimensions of the soil model 4 associated with the contact surface are A×B×C. The calculation formulas are A=a·α, B=b·α, C=c·β, where the lateral expansion coefficient α ranges from 2 to 3, and the longitudinal expansion coefficient β ranges from 1.5 to 2. After determining the outer contour dimensions of the soil model 4 associated with the contact surface using the above method, it is imported into the finite element analysis software along with the support pile model, anchor cable model, and related component models to form a complete simulation model.

[0060] Step S3 involves setting model parameters. At this stage, the material property parameters of the support piles 2, anchor cables 3, and related components need to be defined in the finite element analysis software, and the relevant parameters of the contact surface associated soil model 4 need to be set. The material property parameters of the support piles 2 and anchor cables 3 include elastic modulus, Poisson's ratio, yield strength, etc., which are obtained through laboratory testing or by consulting relevant standards.

[0061] The parameters of the contact surface-associated soil model 4 are set based on the soil foundation physical properties, mechanical properties, soil distribution, and bearing capacity parameters obtained from the sampling analysis in S1. For example, density ρ is used to define the mass distribution of the soil, internal friction angle φ and cohesion c are used to describe the shear strength characteristics of the soil, compression modulus Es is used to reflect the soil's ability to resist compressive deformation, and shear strength is input through data obtained from direct shear tests or triaxial shear tests. In addition, soil layer thickness and soil layer sequence information also need to be accurately reflected in the model to ensure that the simulation results can truly reflect the mechanical behavior of different soil layers.

[0062] Then proceed to step S4: the step-by-step simulation stage.

[0063] The step-by-step simulation includes simulation of soil settlement at the top of the foundation pit, simulation of soil heave at the bottom of the foundation pit, simulation of horizontal displacement of the support piles 2, and simulation of axial tensile stress of the anchor cables 3. For example... Figure 4 As shown, a settlement monitoring area was set at the top of the foundation pit. This area was divided into grids, with the center point of each grid designated as settlement monitoring point 5. Settlement monitoring points 5 were numbered sequentially, and the settlement value was recorded after each simulation. The settlement values ​​for the soil settlement simulation at the top of the foundation pit were randomly generated between 1 mm and 20 mm. The random number generation algorithm ensured that the simulation values ​​could accurately reflect the complex working conditions of the engineering area.

[0064] Similarly, a heave monitoring area was set at the bottom of the foundation pit, and this area was divided into grids. The center point of each grid was designated as heave monitoring point 6. Heave monitoring point 6 was numbered sequentially, and the heave value after each simulation was recorded. The heave value range for the simulated soil heave at the bottom of the foundation pit was randomly generated between 5 mm and 30 mm.

[0065] For the horizontal displacement simulation of the support pile 2, horizontal displacement monitoring points 7 are set at different height positions of the support pile 2, and the horizontal displacement value is recorded after each simulation. The horizontal displacement value is randomly generated between 2 mm and 20 mm.

[0066] The simulation of axial tensile stress in anchor cable 3 involves setting axial tensile stress monitoring points 8 at different locations on anchor cable 3 and recording the axial tensile stress value after each simulation. The range of axial tensile stress values ​​is randomly generated between 100 kPa and 3000 kPa.

[0067] The mechanical behavior of the foundation pit support structure 1 under different working conditions can be comprehensively evaluated through the above step-by-step simulation.

[0068] Finally, we proceed to step S5: the data analysis stage. During data analysis, it is necessary to set the maximum allowable values ​​for settlement, heave, horizontal displacement, and axial tensile stress. These allowable values ​​are determined according to engineering specifications or design requirements. The settlement, heave, horizontal displacement, and axial tensile stress values ​​for each key monitoring point are compared with their corresponding allowable values. Values ​​exceeding the allowable values ​​are output as unqualified analysis results, and simulation parameters are appended to these results. For example, if the settlement value at monitoring point 5 exceeds the maximum allowable settlement value, this monitoring point is marked as unqualified, and its specific settlement value and corresponding simulation parameters are recorded. In this way, potential weak points in the foundation pit support structure 1 can be quickly located, providing a basis for subsequent optimization design.

[0069] The components of the foundation pit support structure mechanical behavior analysis system based on step-by-step simulation are as follows: Figure 5 As shown, the system includes a memory 9, a computer 10, and a display 11. The memory 9 stores the analysis program designed using a step-by-step simulation-based mechanical behavior analysis method for foundation pit support structures. The computer 10 is pre-installed with computer-aided design software and finite element analysis software. The computer 10 communicates with the memory 9, runs the analysis program, and automatically analyzes the foundation pit support structure 1 using the computer-aided design software and finite element analysis software, outputting the step-by-step simulation analysis results and storing them in the memory 9. The display 11 communicates with the computer 10, and the computer 10 controls the display 11 to show the step-by-step simulation process and results. Through this system, the step-by-step simulation analysis of the foundation pit support structure 1 can be automated, and the step-by-step simulation results can be automatically output, displaying relevant data and analysis results.

[0070] In the above embodiments, the components of the foundation pit support structure 1 work collaboratively through precise spatial relationships and mechanical parameter settings. The support piles 2 and anchor cables 3, as load-bearing components, form a stable mechanical system with the surrounding soil through the contact surface-connected soil model 4. The method of expanding the outer contour dimensions of the contact surface-connected soil model 4 ensures that the model can fully reflect the range of the connected soil, thus more closely reflecting the actual engineering situation in the step-by-step simulation. The arrangement of key monitoring points and the data recording method ensure that the simulation results have high accuracy and reliability, providing a scientific basis for the design and construction of the foundation pit support structure 1.

[0071] To enable those skilled in the art to fully understand and implement this invention, the following supplementary explanation of the implementation principle of the method and system for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation, combined with a specific application scenario.

[0072] In step S1, the on-site investigation phase first involves using a drone to perform a three-dimensional scan of the foundation pit support structure 1 and its surrounding environment. For example... Figure 2 As shown, the UAV performs a high-precision scan of the foundation pit support structure 1 along a preset flight path, acquiring spatial distribution and geometric data of the support piles 2, anchor cables 3, and related components. Simultaneously, multiple sampling points are conducted within designated areas on the contact surfaces of the support piles 2 and the soil, as well as the contact surfaces of the anchor cables 3 and the soil. The selection of sampling areas is determined based on actual engineering requirements, typically covering all soil depths involved. Taking a specific project as an example, 3 to 5 sampling points are set per square meter, with the sampling depth evenly distributed from the ground surface to 3 meters below the bottom of the foundation pit. After sampling, basic physical property tests are performed on the soil samples, including the determination of parameters such as density ρ, internal friction angle φ, and cohesion c. These test results will serve as the foundation data for subsequently constructing the contact surface-related soil model 4.

[0073] The process then proceeds to step S2: establishing the simulation model. Based on the 3D scanning data obtained in S1, a geometric model of the foundation pit support structure 1 is constructed using computer-aided design software. For example... Figure 3 As shown, the formulas for calculating the outer contour dimensions of the contact surface associated soil model 4 are A = a·α, B = b·α, and C = c·β, where the lateral expansion coefficient α ranges from 2 to 3, and the longitudinal expansion coefficient β ranges from 1.5 to 2. Taking a real-world engineering project as an example, assuming the outer contour dimensions of the contact surface are a = 10 meters, b = 8 meters, and c = 6 meters, the outer contour dimensions of the contact surface associated soil model 4 can be calculated as A = 20 meters, B = 16 meters, and C = 9 meters. The contact surface associated soil model 4 generated by the above method can fully reflect the extent of the associated soil, thus more closely reflecting the actual engineering situation in the step-by-step simulation.

[0074] In step S3, the process of setting model parameters is further refined. The material property parameters of the support piles 2 and anchor cables 3 are obtained through laboratory tests, such as elastic modulus E = 210 GPa, Poisson's ratio ν = 0.3, and yield strength σy = 350 MPa. The parameters of the contact surface associated soil model 4 are set based on the data obtained from the sampling analysis in S1. For example, density ρ = 1800 kg / m³. 3 The internal friction angle φ = 30° and cohesion c = 20 kPa are used to define the mass distribution of the soil. The shear strength characteristics of the soil are described by φ = 30° and cohesion c = 20 kPa. The compression modulus Es = 15 MPa is used to reflect the soil's ability to resist compressive deformation. Furthermore, the soil layer thickness and sequence information must be accurately represented in the model to ensure that the simulation results truly reflect the mechanical behavior of different soil layers.

[0075] In step S4, the specific operations of the step-by-step simulation are as follows. For example... Figure 4As shown, a settlement monitoring area is set at the top of the foundation pit, and this area is divided into grids, with the center point of each grid designated as settlement monitoring point 5. Taking a specific project as an example, the settlement monitoring area is divided into 10×10 grids, with each grid having a side length of 1 meter, and a total of 100 settlement monitoring points 5 are set. The settlement values ​​for the simulated soil settlement at the top of the foundation pit are randomly generated between 1 mm and 20 mm. The random number generation algorithm ensures that the simulated values ​​can realistically reflect the complex working conditions of the project area. Similarly, a heave monitoring area is set at the bottom of the foundation pit, with the center point of each grid designated as heave monitoring point 6, and the heave value is recorded after each simulation. For the horizontal displacement simulation of the support piles 2, horizontal displacement monitoring points 7 are set at different heights of the support piles 2, and the horizontal displacement value is recorded after each simulation. For the axial tensile stress simulation of the anchor cables 3, axial tensile stress monitoring points 8 are set at different positions of the anchor cables 3, and the axial tensile stress value is recorded after each simulation. Through the above step-by-step simulation, the mechanical behavior of the foundation pit support structure 1 under different working conditions can be comprehensively evaluated.

[0076] Finally, we proceed to step S5: the data analysis stage. During data analysis, it is necessary to set the maximum allowable values ​​for settlement, heave, horizontal displacement, and axial tensile stress. Taking a specific project as an example, the maximum allowable settlement is 20 mm, the maximum allowable heave is 30 mm, the maximum allowable horizontal displacement is 20 mm, and the maximum allowable axial tensile stress is 3000 kPa. The data for each key monitoring point is compared with its corresponding allowable value. Data exceeding the allowable value is output as a non-compliance analysis result, and simulation parameters are added to the non-compliance analysis result. For example, if the settlement value of monitoring point 5 is 22 mm, then this monitoring point is marked as non-compliance, and its specific settlement value and corresponding simulation parameters are recorded. In this way, potential weak points in the foundation pit support structure 1 can be quickly located, providing a basis for subsequent optimization design.

[0077] The operating principle of the foundation pit support structure mechanical behavior analysis system based on step-by-step simulation is as follows: Figure 5 As shown. The memory 9 stores the analysis program. The computer 10 is pre-installed with computer-aided design software and finite element analysis software. The computer 10 communicates with the memory 9, runs the analysis program, and automatically analyzes the foundation pit support structure 1 in conjunction with the computer-aided design software and finite element analysis software. The display 11 communicates with the computer 10, and the computer 10 controls the display 11 to show the step-by-step simulation process and results. Through this system, the step-by-step simulation analysis of the foundation pit support structure 1 can be automated, and the step-by-step simulation results can be automatically output, displaying relevant data and analysis results.

[0078] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation, characterized in that, Includes the following steps: S1: Sampling and analysis to obtain data parameters; Three-dimensional scanning of the foundation pit support structure and its surrounding environment is performed to obtain geometric data and material properties, forming three-dimensional scanning data of the foundation pit support structure; Simultaneously, soil samples were taken and analyzed in the designated area where the foundation pit support structure and the foundation pit were connected to obtain soil distribution, physical properties, and mechanical parameters. S2: Establish a simulation model; Based on the obtained three-dimensional scanning data of the foundation pit support structure, construct a geometric model of the foundation pit support structure, the geometric model including the contact surface associated soil model; S3: Set model parameters; Define the material property parameters of the support piles, anchor cables and related components in the model, and set the relevant parameters of the contact surface associated with the soil model; S4: Step-by-step simulation; Step-by-step simulation is performed using finite element analysis software; The step-by-step simulation includes the simulation of soil settlement at the top of the foundation pit, the simulation of soil heave at the bottom of the foundation pit, the simulation of horizontal displacement of the support piles, and the simulation of axial tensile stress of the anchor cable. Set up key monitoring points and record the displacement or stress data of the key monitoring points after each simulation; S5: Data Analysis; Based on the data from key monitoring points, perform step-by-step simulation analysis, and output the mechanical behavior analysis results of the foundation pit support structure based on the comparison results of the preset thresholds.

2. The method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 1, characterized in that, The geometric model in step S2 also includes a support pile model, an anchor cable model, and related component models; The contact surface associated soil model is generated by extending the contact surface between the support pile model, anchor cable model and related component models and the soil on the side and bottom of the foundation pit; The outer contour dimensions of the contact surface are set to a×b×c, where a is the length of the side, b is the width of the side, and c is the depth. The outer contour of the soil model associated with the contact surface is a cuboid. Based on the outer contour dimensions of the contact surface, the outer contour cuboid dimensions of the soil model associated with the contact surface are calculated to be A×B×C.

3. The method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 2, characterized in that, The method for calculating the dimensions of the cuboid outer contour of the soil model associated with the contact surface is as follows: A=a·α; B=b·α; C=c·β; In the formula, α is the horizontal expansion coefficient, which ranges from 2 to 3; β is the longitudinal expansion coefficient, which ranges from 1.5 to 2.

4. The method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 3, characterized in that, In step S1, the soil region corresponding to the cuboid region of the outer contour of the soil model associated with the contact surface is used for sampling and analysis. The sampling analysis is based on the soil at multiple sampling points in the soil region corresponding to the outer contour cuboid region of the contact surface associated soil model, to obtain basic physical properties, mechanical properties, soil distribution and bearing capacity parameters.

5. The method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 4, characterized in that, In step S3, the parameters of the soil model associated with the contact surface are set based on the soil physical properties, mechanical properties, soil distribution and bearing capacity parameters obtained from the sampling analysis in step S1.

6. The method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 5, characterized in that, In step S4, the specific method for simulating the settlement of the soil at the top of the foundation pit is as follows: a settlement monitoring area is set at the top of the foundation pit, the area is divided into grids, the center point of each grid is a settlement monitoring point, the settlement monitoring points are numbered sequentially, and the settlement value after each simulation is recorded. The specific method for simulating soil heave at the bottom of the foundation pit is as follows: a heave monitoring area is set at the bottom of the foundation pit, the area is divided into grids, the center point of each grid is the heave monitoring point, the heave monitoring points are numbered sequentially, and the heave value after each simulation is recorded. The specific method for simulating the horizontal displacement of the support pile is as follows: set horizontal displacement monitoring points at different heights of the support pile and record the horizontal displacement value after each simulation. The specific method for simulating the axial tensile stress of anchor cables is as follows: set axial tensile stress monitoring points at different locations on the anchor cable and record the axial tensile stress value after each simulation.

7. The method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 6, characterized in that, The settlement values ​​for the simulated soil settlement at the top of the foundation pit are randomly generated between 1 mm and 20 mm; the heave values ​​for the simulated soil heave at the bottom of the foundation pit are randomly generated between 5 mm and 30 mm; the horizontal displacement values ​​for the simulated horizontal displacement of the support piles are randomly generated between 2 mm and 20 mm; and the axial tensile stress values ​​for the simulated axial tensile stress of the anchor cables are randomly generated between 100 kPa and 3000 kPa.

8. The method for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 7, characterized in that, In step S5, the maximum allowable values ​​for settlement, heave, horizontal displacement, and axial tensile stress are set. The settlement, heave, horizontal displacement, and axial tensile stress values ​​of each key monitoring point are compared with the corresponding allowable values. If the values ​​exceed the corresponding allowable values, the non-compliance analysis results are output, and simulation parameters are added to the non-compliance analysis results.

9. A system for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation, characterized in that, The system includes a memory and a computer. The memory stores an analysis program designed using the step-by-step simulation-based mechanical behavior analysis method for foundation pit support structures as described in any one of claims 1 to 8. The computer is pre-installed with computer-aided design software and finite element analysis software. The computer is communicatively connected to the memory and is used to run the analysis program. It also associates the computer-aided design software and finite element analysis software to automatically analyze the foundation pit support structure and outputs the step-by-step simulation analysis results, which are then stored in the memory.

10. The system for analyzing the mechanical behavior of foundation pit support structures based on step-by-step simulation according to claim 9, characterized in that, Also includes: The display is communicatively connected to a computer, and the computer controls the display to show the step-by-step simulation process and the step-by-step simulation results.

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