A Method for Mechanical Property Analysis of Reinforced Concrete Segments in Shield Tunnels

Abstract

This invention provides a method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels, comprising the following steps: Step 1, constructing a three-dimensional aggregate model database; Step 2, constructing a first aggregate packing model based on the three-dimensional aggregate model; Step 3, establishing three-dimensional models of each component constituting the concrete segment; Step 4, constructing a three-dimensional model of a heterogeneous reinforced concrete segment; Step 5, constructing a three-dimensional model of the strata and a three-dimensional model of the grouting layer; Step 6, constructing a three-dimensional model of a heterogeneous reinforced concrete segment in a shield tunnel; Step 7, performing stress analysis on the three-dimensional model of the heterogeneous reinforced concrete segment in a shield tunnel. This invention can more realistically reflect the random distribution characteristics of aggregates inside concrete, as well as the interaction relationships between aggregates and concrete, reinforcing steel and concrete, and the grouting layer. It can more accurately capture the non-uniformity and complexity of the concrete microstructure, thereby more comprehensively revealing the micromechanical properties of the segment during the stress process.

Description

Technical Field

[0001] This invention relates to a method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels, belonging to the field of shield tunnel segment construction technology. Background Technology

[0002] With the acceleration of urbanization, the development and utilization of underground space has become an important part of modern urban construction. Shield tunneling, as a highly efficient and environmentally friendly tunnel construction method, is widely used in urban subways, underground utility tunnels, and other projects. However, under complex geological conditions, the segment structure of shield tunnels often faces multiple challenges such as seepage, water pressure, and uneven geological formations, leading to problems such as cracking, misalignment, leakage, and even localized collapse. Therefore, the safety and stability control of segment structures, especially the assurance of mechanical properties and durability under complex geological conditions, has always been a research hotspot in academia and engineering.

[0003] Currently, most mechanical performance analyses of tunnel shield segments are based on homogeneous concrete materials, neglecting the heterogeneous characteristics of aggregates and voids within the concrete. This neglects the influence of aggregate geometry on segment stress, leading to significant discrepancies between the numerical simulation results and actual stress conditions. Consequently, these models fail to accurately reflect stress distribution, crack propagation, and damage evolution under complex geological conditions. Furthermore, the prevalence of two-dimensional planar or cross-sectional models for tunnel shield segments, when used for mechanical performance analysis, is insufficient in terms of spatial distribution characteristics, three-dimensional interactions between aggregates, and overall structural integrity. Two-dimensional models cannot fully capture the multi-scale spatial heterogeneity within concrete, limiting their application in microscopic damage evolution and fracture mechanism research. Therefore, overcoming the limitations of two-dimensional modeling and establishing a modeling method that realistically represents the spatial distribution of aggregates within concrete and the multi-interface interactions between aggregates, reinforcing steel, grouting layers, and the geological strata has become a key technical challenge for improving the accuracy and applicability of mechanical performance analysis for tunnel shield segments. Summary of the Invention

[0004] This invention provides a method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels, which can more accurately capture the non-uniformity and complexity of the concrete microstructure, thereby more comprehensively revealing the micromechanical properties of the segments during the stress process.

[0005] To address the aforementioned technical problems, this invention provides a method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels, comprising the following steps: Step 1: Constructing a three-dimensional aggregate model database: Acquiring two-dimensional images of multiple aggregate samples, and converting each aggregate sample's two-dimensional image into a three-dimensional aggregate model using voxelization, and saving it to the three-dimensional aggregate model database to construct the three-dimensional aggregate model database; Step 2: Constructing a first aggregate packing model based on the three-dimensional aggregate model, wherein the first aggregate packing model contains aggregates with multi-gradation and irregular shapes; Step 3: Determining the dimensions of the concrete segments according to the engineering area design drawings, and accordingly establishing three-dimensional models of each component constituting the concrete segments; the components of the concrete segments include four standard blocks, two connecting blocks, and a wedge-shaped component. The capping block; four standard blocks are set between two connecting blocks, and the capping block is set between the two connecting blocks. The various components of the concrete segment are connected by bolts; Step 4: Construct a heterogeneous reinforced concrete segment 3D model based on the first aggregate accumulation model and the 3D model of each component of the concrete segment; Step 5: Construct a 3D model of the stratum and a 3D model of the grouting layer based on the heterogeneous reinforced concrete segment 3D model; Step 6: Construct a heterogeneous shield tunnel reinforced concrete segment 3D model: combine the heterogeneous reinforced concrete segment 3D model, the stratum 3D model, and the grouting layer 3D model to generate a heterogeneous shield tunnel reinforced concrete segment 3D model based on the stratum structure method; Step 7: Perform stress analysis on the heterogeneous shield tunnel reinforced concrete segment 3D model.

[0006] In one specific implementation, step 2 specifically comprises: Step 2.1, setting the aggregate generation domain in the discrete element method (PFC) software according to the concrete segment dimensions; Step 2.2, setting the porosity and aggregate gradation radius range, and generating circular aggregates with different gradations within the generation domain using a particle generation algorithm to generate a circular aggregate model; Step 2.3, replacing any circular aggregate in the circular aggregate model with a randomly selected three-dimensional aggregate model from the aggregate three-dimensional model database, until all circular aggregates in the circular aggregate model are replaced with three-dimensional aggregate models to generate an initial aggregate packing model, wherein the principle of equal volume replacement is used to ensure that the volume of the replaced aggregate three-dimensional model is the same as the volume of the corresponding circular aggregate; Step 2.4, converting the initial aggregate packing model into a file format compatible with the finite element numerical analysis software ABAQUS using MATLAB to generate the first aggregate packing model.

[0007] In one specific implementation, in step 2.3, the three-dimensional model of the aggregate is placed at the position of the corresponding circular aggregate based on random angles and random displacements.

[0008] In one specific implementation, step 3 specifically involves: constructing a three-dimensional model of each component constituting the concrete segment in the finite element numerical analysis software ABAQUS, based on the dimensions of the concrete segment.

[0009] In one specific implementation, step 4 specifically comprises: Step 4.1, cutting the first aggregate stacking model to obtain seven second aggregate stacking models, each with the same shape as the four standard blocks, two connecting blocks, and one capping block of the concrete segment; Step 4.2, importing the seven second aggregate stacking models into the finite element numerical analysis software ABAQUS, and merging each second aggregate stacking model with the corresponding component of the concrete segment through Boolean operations to generate the corresponding component of the concrete segment containing the second aggregate stacking model; Step 4.3, splicing the components of the concrete segment containing the second aggregate stacking model to form a heterogeneous three-dimensional model of the concrete segment; Step 4.4, adding bolts and reinforcing bars to the heterogeneous three-dimensional model of the concrete segment to construct a heterogeneous reinforced concrete segment three-dimensional model.

[0010] In one specific implementation, step 7 specifically includes the following steps: Step 7.1, assigning material data to the engineering area of ​​the heterogeneous shield tunnel reinforced concrete segment 3D model, and setting the interaction and contact relationships between aggregate and concrete, steel reinforcement and concrete, heterogeneous reinforced concrete segment and grouting layer, and grouting layer and stratum; Step 7.2, meshing the heterogeneous shield tunnel reinforced concrete segment 3D model; Step 7.3, assigning boundary conditions and loads to the engineering area of ​​the heterogeneous shield tunnel reinforced concrete segment 3D model; Step 7.4, performing mechanical property analysis on the heterogeneous shield tunnel reinforced concrete segment 3D model using a static general analysis step.

[0011] In one specific implementation, step 7.4 specifically includes: creating a static general analysis step for the three-dimensional model of the heterogeneous shield tunnel reinforced concrete segment in the finite element numerical analysis software ABAQUS, setting the time increment and maximum increment step number, enabling nonlinear geometric effects, specifying the output frequency, outputting mechanical data in the defined field, defining historical output variables, and recording the displacement, reaction force, and contact force time history of the nodes at the top, bottom, and side abutments of the heterogeneous shield tunnel reinforced concrete segment; and analyzing the overall horizontal displacement, vertical settlement, and convergence deformation of the heterogeneous shield tunnel reinforced concrete segment through the visualization module of the finite element numerical analysis software ABAQUS.

[0012] In one specific implementation, in step 1, two-dimensional images of multiple aggregate samples are acquired using the AIMS2 aggregate image analysis system.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0014] 1. This invention acquires two-dimensional images of real aggregates to generate a three-dimensional aggregate model. Based on the three-dimensional aggregate model, a first aggregate packing model containing multi-graded and irregularly shaped aggregates is generated. Based on the first aggregate packing model, a heterogeneous reinforced concrete segment is generated, and then a three-dimensional model of the heterogeneous shield tunnel reinforced concrete segment is constructed and subjected to stress analysis. The three-dimensional model of the heterogeneous shield tunnel reinforced concrete segment can accurately simulate the aggregate distribution characteristics of the segment containing aggregates of different particle sizes, different gradations, and different porosities, as well as the interaction relationships between aggregates, concrete, reinforcing steel, grouting layer, and strata. In the mechanical performance analysis process, it can more accurately capture the non-uniformity and complexity of the concrete microstructure, thereby more comprehensively revealing the micromechanical properties of the segment during the stress process.

[0015] 2. This invention constructs a first aggregate packing model containing multi-grade aggregates with irregular shapes using discrete element method software, which can significantly improve modeling efficiency and make it easier and more flexible to adjust model parameters. Attached Figure Description

[0016] Figure 1 A flowchart illustrating the mechanical property analysis method for reinforced concrete segments in shield tunnels provided in this embodiment of the invention.

[0017] Figure 2 A schematic diagram of the first aggregate stacking model provided for an embodiment of the invention.

[0018] Figure 3 A side view of a three-dimensional model of a heterogeneous reinforced concrete segment provided in an embodiment of the present invention.

[0019] Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0020] Figure 5 A schematic diagram of a three-dimensional model of a non-homogeneous shield tunnel reinforced concrete segment provided in an embodiment of the present invention.

[0021] Legend: 1. Three-dimensional model of heterogeneous reinforced concrete segment; 2. Three-dimensional model of grouting layer; 3. Three-dimensional model of stratum; 4. Three-dimensional model of aggregate. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0023] refer to Figure 1A method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels includes the following steps: Step 1: Constructing a three-dimensional aggregate model database: Collect two-dimensional images of multiple aggregate samples, and convert the two-dimensional images of each aggregate sample into a three-dimensional aggregate model using a voxelization method, and save it to the three-dimensional aggregate model database to construct the three-dimensional aggregate model database.

[0024] Specifically, in step 1, two-dimensional images of multiple aggregate samples are acquired using the AIMS2 aggregate image analysis system.

[0025] For each aggregate 2D image, denoising, binarization segmentation, interlayer registration, and aggregate contour extraction are performed. The layers are stacked vertically according to the interlayer spacing to generate the corresponding 3D voxel matrix. Interpolation filling and surface smoothing optimization are performed on the 3D voxel matrix to generate the corresponding aggregate 3D model.

[0026] Step 2: Construct a first aggregate packing model based on the three-dimensional aggregate model. The first aggregate packing model contains aggregates with multiple gradations and irregular shapes.

[0027] In this embodiment, based on the design drawings of the engineering area, the specific dimensions of the concrete segment are determined as follows: outer diameter of 8.8m, inner diameter of 8m, and height of 1.8m.

[0028] Preferably, step 2 specifically comprises:

[0029] Step 2.1: Based on the design drawings of the engineering area, determine the size of the concrete segments in the engineering area. In the discrete element software PFC, set the aggregate generation domain according to the size of the concrete segments. The generation domain is a cuboid region with a length of 8.8m, a width of 8.8m, and a height of 1.8m.

[0030] Step 2.2 Set the porosity and aggregate gradation radius range, and generate circular aggregates with different gradations within the generation domain using a particle generation algorithm to generate a circular aggregate model.

[0031] Specifically, referring to the "Concrete Quality Control Standard" and practical construction experience, and considering the calculation requirements of the discrete element three-dimensional microstructure model, the minimum particle size of the circular aggregate in the circular aggregate model is set to 0.02m, and the maximum particle size is set to 0.15m. The circular aggregate is divided into three particle size gradations. The particle size d of the circular aggregate in the first particle size gradation ranges from 0.02m to 0.04m; the particle size d of the circular aggregate in the second particle size gradation ranges from 0.04m to 0.08m; and the particle size d of the circular aggregate in the third particle size gradation ranges from 0.08m to 0.15m. The mass of the circular aggregate accounts for 10% of the concrete mass. The first particle size gradation accounts for 26.71% of all circular aggregate, the second particle size gradation accounts for 36.61%, and the third particle size gradation accounts for 36.68%. The required particle size of the circular aggregate in each particle size gradation should meet the following requirements:

[0032]

[0033] d x P(d) represents the particle size to be determined. x ) is a known particle size d x The passing rate of circular aggregate with a known particle size distribution; d1 is the smaller endpoint value of the known particle size distribution, d2 is the larger endpoint value of the known particle size distribution, P(d1) is the passing rate of circular aggregate with a particle size of d1, and P(d2) is the passing rate of circular aggregate with a particle size of d2.

[0034] Step 2.3: Replace any circular aggregate in the circular aggregate model with a 3D aggregate model randomly selected from the aggregate 3D model database, until all circular aggregates in the circular aggregate model are replaced with 3D aggregate models to generate the initial aggregate packing model. The principle of equal volume replacement is used to ensure that the volume of the replaced aggregate 3D model is the same as the volume of the corresponding circular aggregate.

[0035] Preferably, in step 2.3, the three-dimensional model of the aggregate is placed at the position of the corresponding circular aggregate based on random angle and random displacement, so that the three-dimensional model of the aggregate is distributed more naturally in the generation domain.

[0036] Step 2.4: Convert the initial aggregate packing model into a file format compatible with the finite element numerical analysis software ABAQUS using MATLAB to generate the first aggregate packing model. (See [link to relevant documentation]). Figure 2 .

[0037] The initial aggregate packing model generated in the discrete element method software is in STL format. MATLAB is used to convert the initial aggregate packing model file format to IGES to facilitate import into the finite element numerical analysis software ABAQUS.

[0038] Step 3: Based on the engineering area design drawings, determine the dimensions of the concrete pipe segments and establish a three-dimensional model of each component constituting the concrete pipe segments. The components of the concrete pipe segments include four standard blocks, two connecting blocks, and a wedge-shaped capping block. The four standard blocks are placed between the two connecting blocks, and the capping block is placed between the two connecting blocks. The components of the concrete pipe segments are connected by bolts. The wedge-shaped capping block is used, and its spatial fit with the connecting blocks on both sides achieves the geometric closure and structural stability of the concrete pipe segments.

[0039] Specifically, step 3 involves constructing a three-dimensional model of each component constituting the concrete segment in the finite element numerical analysis software ABAQUS, based on the dimensions of the concrete segments in the engineering area.

[0040] Step 4: Based on the first aggregate packing model and the 3D model of each component of the concrete segment, construct a non-homogeneous reinforced concrete segment 3D model. (Refer to...) Figure 3 and Figure 4 .

[0041] Specifically, step 4 is as follows: Step 4.1: Cut the first aggregate stacking model to obtain seven second aggregate stacking models that are respectively identical in shape to the four standard blocks, two connecting blocks and one capping block of the concrete pipe segment.

[0042] Step 4.2: Import the seven second aggregate packing models into the finite element numerical analysis software ABAQUS. Use Boolean operations to merge each second aggregate packing model with the corresponding concrete segment component to generate the corresponding concrete segment component containing the second aggregate packing model, thus realizing the random distribution of aggregate in each component of the concrete segment.

[0043] Step 4.3: Assemble the concrete segment components containing the second aggregate stacking model to form a heterogeneous three-dimensional model of the concrete segment.

[0044] Step 4.4: Add bolts and reinforcing bars to the heterogeneous concrete segment 3D model to construct a heterogeneous reinforced concrete segment 3D model. The aggregate in the reinforced concrete segment 3D model is randomly distributed.

[0045] Create a 3D line body with a radius of 1m as a bolt. Set two bolts at the connection of adjacent reinforced concrete segments. The bolts are located at the third point of the cross section of the non-homogeneous reinforced concrete segment.

[0046] Create a 3D line body with a radius of 4.1m as a reinforcing bar. The reinforcing bar can be imported into the appropriate position of the heterogeneous concrete segment using the rotate and translate commands.

[0047] Step 5: Construct a three-dimensional model of the formation and a three-dimensional model of the grouting layer based on the three-dimensional model of the heterogeneous concrete segment.

[0048] Create a 3D extruded solid in the shape of a cylinder with a diameter of 9m. Then, cut off a portion of the cylinder with a diameter of 8.8m at its center to construct a 3D model of a grouting layer with a thickness of 0.2m.

[0049] Create a 3D extruded solid in the shape of a cuboid, with a length of 12m, a width of 12m, and a height of 1.8m. Then, cut off a cylinder with a diameter of 9m at its center to construct a 3D model of the geological formation.

[0050] Step 6: Construct a 3D model of the reinforced concrete segment of the shield tunnel: Combine the 3D model of the heterogeneous reinforced concrete segment, the 3D model of the strata, and the 3D model of the grouting layer to generate a 3D model of the heterogeneous reinforced concrete segment of the shield tunnel based on the strata structure method. (See [reference]) Figure 5 .

[0051] Step 7: Perform stress analysis on the three-dimensional model of the non-homogeneous shield tunnel reinforced concrete segment.

[0052] Specifically, step 5 includes the following steps: Step 5.1: Assign material data to the engineering area of ​​the three-dimensional model of the non-homogeneous shield tunnel reinforced concrete segment, and set the interaction and contact relationships between aggregate and concrete, steel bars and concrete, non-homogeneous reinforced concrete segment and grouting layer, and grouting layer and stratum.

[0053] Aggregates are defined as high-stiffness elastic bodies, reinforcing bars are modeled using an elastoplastic model, heterogeneous reinforced concrete segments are modeled using a concrete damage plasticity model, grouting layers are considered for elastoplastic properties, and soil-water coupling behavior is considered for the soil strata. By defining "surface-to-surface contact" and "embedded region" constraints, the mechanical transmission and interaction between aggregates and concrete, reinforcing bars and concrete, heterogeneous reinforced concrete segments and grouting layers, and grouting layers and soil strata are simulated.

[0054] Step 5.2: Mesh the 3D model of the non-homogeneous shield tunnel reinforced concrete segment.

[0055] Global seeds are set for heterogeneous reinforced concrete segments, aggregates, bolts, reinforcing bars, grouting layers, and ground layers. The global seed size for heterogeneous reinforced concrete segments, aggregates, bolts, and reinforcing bars is smaller than the global seed size for grouting layers and ground layers.

[0056] The interface between aggregate and concrete is locally refined, and the irregular surface geometry is simplified by virtual topology.

[0057] Non-homogeneous reinforced concrete segments and aggregates were analyzed using C3D10M tetrahedral elements, while the grouting layer and soil strata were analyzed using C3D8R hexahedral elements. Reinforcing steel was analyzed using either T3D2 truss elements or C3D8R solid elements, depending on the model type. Soil-water coupling analysis of the soil strata was performed using C3D8P pore pressure elements. After mesh generation, the element aspect ratio and twist were checked, and the alignment of contact surface nodes was ensured.

[0058] Step 5.3: Assign boundary conditions and loads to the engineering area of ​​the non-homogeneous shield tunnel reinforced concrete segment 3D model.

[0059] Setting boundary conditions specifically includes: fixing the bottom of the stratum to limit displacement and rotation in the X, Y, and Z directions, and constraining the sides of the stratum to limit the displacement of the ends of the heterogeneous reinforced concrete segments.

[0060] In this embodiment, applying the load specifically includes: applying uniform pressure to the outer surface of the heterogeneous reinforced concrete segment, applying uniformly distributed surface force to the top of the stratum, defining an initial stress field on the prestressed steel section, and defining gravity load in the global coordinate system based on the borehole columnar section data of the engineering area.

[0061] Verify the direction, area of ​​action, and values ​​of all boundary conditions and loads to ensure they are consistent with the corresponding information of the engineering area, thereby accurately reproducing the stress state of the segment structure in complex strata.

[0062] Step 5.4: Perform mechanical property analysis on the three-dimensional model of the non-homogeneous shield tunnel reinforced concrete segment using the static general analysis step.

[0063] Specifically, in step 5.4, a static general analysis step is used to analyze the mechanical properties of the three-dimensional model of the heterogeneous shield tunnel reinforced concrete segment. This includes: creating a static general analysis step for the three-dimensional model of the heterogeneous shield tunnel reinforced concrete segment in the finite element numerical analysis software ABAQUS, setting the time increment and maximum increment step number, enabling nonlinear geometric effects, specifying the output frequency, outputting mechanical data in the defined field, defining historical output variables, and recording the displacement, reaction force, and contact force time history of the nodes at the top, bottom, and side abutments of the heterogeneous shield tunnel reinforced concrete segment; and analyzing the overall horizontal displacement, vertical settlement, and convergence deformation of the heterogeneous shield tunnel reinforced concrete segment through the visualization module of the ABAQUS finite element numerical analysis software, thereby evaluating the stress performance of the heterogeneous reinforced concrete segment and the stratum containing the aggregate accumulation model.

[0064] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions and substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels, characterized in that, Includes the following steps: Step 1: Construct a 3D aggregate model database: Collect 2D images of multiple aggregate samples, convert each aggregate sample's 2D image into a 3D aggregate model using voxelization, and save the images to the 3D aggregate model database to construct the 3D aggregate model database. Step 2: Construct a first aggregate packing model based on the three-dimensional aggregate model. The first aggregate packing model contains aggregates with multiple gradations and irregular shapes. Step 3: Based on the engineering area design drawings, determine the dimensions of the concrete pipe segments and establish a three-dimensional model of each component that makes up the concrete pipe segments. The components of the concrete pipe segments include four standard blocks, two connecting blocks, and a wedge-shaped capping block. The four standard blocks are set between the two connecting blocks, and the capping block is set between the two connecting blocks. The components of the concrete pipe segments are connected by bolts. Step 4: Construct a non-homogeneous 3D model of reinforced concrete tunnel segments based on the first aggregate stacking model and the 3D model of each component of the concrete tunnel segment; Step 5: Construct a three-dimensional model of the formation and a three-dimensional model of the grouting layer based on the three-dimensional model of the heterogeneous reinforced concrete segment; Step 6: Construct a heterogeneous 3D model of reinforced concrete tunnel segments: Combine the heterogeneous 3D model of reinforced concrete tunnel segments, the 3D model of the stratum, and the 3D model of the grouting layer to generate a heterogeneous 3D model of reinforced concrete tunnel segments based on the stratum structure method. Step 7: Perform stress analysis on the three-dimensional model of the non-homogeneous shield tunnel reinforced concrete segment.

2. The method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels as described in claim 1, characterized in that, Step 2 specifically involves: Step 2.1: Based on the dimensions of the concrete segments, set the aggregate generation domain in the Discrete Element Method (PFC) software; Step 2.2: Set the porosity and aggregate gradation radius range, and generate circular aggregates with different gradations within the generation domain using a particle generation algorithm to generate a circular aggregate model; Step 2.3: Replace any circular aggregate in the circular aggregate model with a three-dimensional aggregate model randomly selected from the aggregate three-dimensional model database, until all circular aggregates in the circular aggregate model are replaced with three-dimensional aggregate models to generate the initial aggregate packing model. The principle of equal volume replacement is used to ensure that the volume of the replaced aggregate three-dimensional model is the same as the volume of the corresponding circular aggregate. Step 2.4: Use MATLAB to convert the initial aggregate packing model into a file format compatible with the finite element numerical analysis software ABAQUS to generate the first aggregate packing model.

3. The method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels as described in claim 2, characterized in that, In step 2.3, the three-dimensional model of the aggregate is placed at the position of the corresponding circular aggregate based on random angles and random displacements.

4. The method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels as described in claim 3, characterized in that, Step 3 specifically involves: constructing a three-dimensional model of each component constituting the concrete segment in the finite element numerical analysis software ABAQUS, based on the dimensions of the concrete segment.

5. The method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels as described in claim 4, characterized in that, Step 4 specifically involves: Step 4.1: Cut the first aggregate stacking model to obtain seven second aggregate stacking models that are identical in shape to the four standard blocks, two connecting blocks and one capping block of the concrete pipe segment. Step 4.2: Import the seven second aggregate packing models into the finite element numerical analysis software ABAQUS, and merge each second aggregate packing model with the corresponding concrete segment component through Boolean operations to generate the corresponding concrete segment component containing the second aggregate packing model. Step 4.3: Assemble the concrete segment components containing the second aggregate stacking model to form a heterogeneous three-dimensional model of the concrete segment; Step 4.4: Add bolts and reinforcing bars to the heterogeneous concrete segment 3D model to construct the heterogeneous reinforced concrete segment 3D model.

6. The method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels as described in claim 5, characterized in that, Step 7 specifically includes the following steps: Step 7.1: Assign material data to the engineering area of ​​the three-dimensional model of the heterogeneous shield tunnel reinforced concrete segment, and set the interaction and contact relationships between aggregate and concrete, steel reinforcement and concrete, heterogeneous reinforced concrete segment and grouting layer, and grouting layer and stratum. Step 7.2: Mesh the 3D model of the non-homogeneous shield tunnel reinforced concrete segment; Step 7.3: Assign boundary conditions and loads to the engineering area of ​​the non-homogeneous shield tunnel reinforced concrete segment 3D model; Step 7.4: Perform mechanical property analysis on the three-dimensional model of the non-homogeneous shield tunnel reinforced concrete segment using the static general analysis step.

7. The method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels as described in claim 6, characterized in that, Step 7.4 specifically includes: in the finite element numerical analysis software ABAQUS, creating a static general analysis step for the three-dimensional model of the heterogeneous shield tunnel reinforced concrete segment, setting the time increment and maximum increment step number, enabling nonlinear geometric effects, specifying the output frequency, outputting mechanical data in the defined field, defining historical output variables, and recording the displacement, reaction force, and contact force time history of the nodes at the top, bottom, and both sides of the heterogeneous shield tunnel reinforced concrete segment; and analyzing the overall horizontal displacement, vertical settlement, and convergence deformation of the heterogeneous shield tunnel reinforced concrete segment through the visualization module of the finite element numerical analysis software ABAQUS.

8. The method for analyzing the mechanical properties of reinforced concrete segments in shield tunnels as described in claim 1, characterized in that, In step 1, two-dimensional images of multiple aggregate samples are acquired using the AIMS2 aggregate image analysis system.

Images