A method and system for modeling nonlinear strata springs in tunnels

Abstract

This invention provides a method and system for modeling nonlinear ground springs in tunnels, relating to the field of shield tunnel simulation technology. The method includes: acquiring target node information based on a pre-established shield tunnel model, the target node information including the position and element number information of unit nodes on the shield tunnel surface; calculating the unit area represented by the target node based on the target node information by constraining model displacement and applying pressure to the tunnel surface, obtaining a first dataset, the first dataset including the unit area represented by each target node; establishing a spring model for each target node based on the target node information; and generating nonlinear stiffness data for the normal spring and the first and second tangential springs based on the first dataset and preset ground information, obtaining a spring model with nonlinear stiffness. This invention can quickly and accurately extract the unit area represented by nodes on the shield tunnel surface, customize the nonlinear stiffness of the ground springs, and quickly import them into shield tunnel models in batches.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel simulation technology, and more specifically, to a method and system for modeling nonlinear ground springs in tunnels. Background Technology

[0002] In the three-dimensional refined numerical calculation model of shield tunnel segment structure, there are two main methods for simulating the interaction between the tunnel and the strata: one is to use solid elements to model the surrounding strata. The disadvantage of this method is that it cannot apply explicit earth pressure loads to the segment lining structure, nor can it apply water pressure. Moreover, this method greatly increases the number of calculation elements, thus affecting the calculation efficiency. The other method is to use circumferential strata springs to simulate the interaction between the strata and the segment lining structure. This method can separate the earth pressure loads and water pressure loads and can reduce the number of elements. This method has been widely used in the calculation of the mechanical properties of shield tunnel segment structures.

[0003] While the spring elements provided in ABAQUS can simulate most springs, simulating ground springs presents the following problems: The ground springs required for calculating the mechanical properties of shield tunnel segment structures should have nonlinear properties, meaning they should only be subjected to compression and not tension. However, the springs in ABAQUS are linear, which does not meet this requirement. Furthermore, due to the complexity of the shield tunnel segment lining model, the element mesh areas of the tunnel segment lining vary, and the stiffness of each spring should also be different. Existing methods set the stiffness of each spring to an equal value, which also does not meet the requirements. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for modeling nonlinear geological springs in tunnels, thereby improving the aforementioned problems. To achieve this objective, the technical solution adopted by this invention is as follows:

[0005] Firstly, this application provides a method for modeling nonlinear ground springs in tunnels, including:

[0006] Target node information is obtained based on a pre-established shield tunnel model. The target node information includes the location information and unit number information of the unit nodes on the outer surface of the shield tunnel.

[0007] Based on the target node information, the reaction force of the unit node is obtained by constraining the model displacement and applying unit pressure to the tunnel surface, and the unit area represented by the unit node is calculated to obtain the first dataset, which includes the unit area of ​​the target node.

[0008] Based on the target node information, a spring model is established for each target node. The spring model includes a normal spring, a first tangential spring, and a second tangential spring. The axis of the normal spring is perpendicular to the shield tunnel axis, and the axis of the first tangential spring is parallel to the shield tunnel axis. The axes of the normal spring, the first tangential spring, and the second tangential spring form a left / right-hand coordinate system.

[0009] Based on the first dataset and the preset geological information, nonlinear stiffness data are generated for the normal spring, the first tangential spring and the second tangential spring, respectively, to obtain a spring model with nonlinear stiffness.

[0010] Secondly, this application also provides a tunnel nonlinear stratum spring modeling system, comprising:

[0011] The first acquisition module is used to acquire target node information based on a pre-established shield tunnel model. The target node information includes the position information and unit number information of the unit nodes on the outer surface of the shield tunnel.

[0012] The second acquisition module is used to obtain the unit node reaction force and calculate the unit area represented by the unit node based on the target node information by constraining the model displacement and applying unit pressure to the tunnel surface, thereby obtaining a first dataset, which includes the unit area of ​​the target node.

[0013] The first construction module is used to build a spring model for each target node based on the target node information. The spring model includes a normal spring, a first tangential spring, and a second tangential spring. The axis of the normal spring is perpendicular to the shield tunnel axis, and the axis of the first tangential spring is parallel to the shield tunnel axis. The axes of the normal spring, the first tangential spring, and the second tangential spring form a left / right-hand coordinate system.

[0014] The first generation module is used to generate nonlinear stiffness data for the normal spring, the first tangential spring, and the second tangential spring based on the first dataset and preset geological information, so as to obtain a spring model with nonlinear stiffness.

[0015] The beneficial effects of this invention are as follows:

[0016] This invention solves the problem that ABAQUS cannot output the surface area of ​​a unit node by constraining the displacement of the model and applying unit pressure to the tunnel surface, making the output nodal reaction force equal to the area of ​​the unit node. It is simple and practical to operate, and can quickly and accurately extract the area of ​​the unit representing the node through an equivalent method. After constructing the stratum spring, the stiffness of the stratum spring can be customized using the unit area, so that the stratum springs of different units have different nonlinear stiffnesses, which meets the actual requirements.

[0017] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the tunnel nonlinear stratum spring modeling method according to an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the cylindrical coordinate system and the surface reference coordinate system in an embodiment of this application;

[0021] Figure 3 This is a structural diagram of the tunnel nonlinear stratum spring modeling system according to an embodiment of this application.

[0022] Marked in the image:

[0023] 400 - First Acquisition Module; 500 - Second Acquisition Module; 600 - First Construction Module; 610 - First Construction Unit; 620 - Second Construction Unit; 630 - Third Construction Unit; 700 - First Generation Module; 710 - First Calculation Unit; 720 - Second Calculation Unit; 730 - First Generation Unit; 740 - Second Generation Unit; 750 - Third Generation Unit; 760 - First Loading Unit; 770 - Fourth Construction Unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] The lining structure of shield tunnel segments is usually an underground prefabricated structure made of reinforced concrete segments connected by bolts. Its mechanical properties are often studied through theoretical analysis, full-scale tests and numerical simulation. Among them, numerical simulation has become an important means of studying the mechanical properties of shield tunnel segment structures due to its advantages of low cost, strong repeatability and ease of implementation.

[0027] ABAQUS, with its powerful nonlinear analysis capabilities and rich material model library, has become the preferred software for calculating the mechanical properties of shield tunnel segment structures. Therefore, accurately simulating the interaction between the shield tunnel and the ground strata in ABAQUS is crucial to ensuring reliable calculation results. The spring elements provided in ABAQUS can simulate most springs. For example, one node (implicit and not requiring definition) of the ground spring (Spring1) is stationary, while the other node is defined on the node requiring constraint. However, directly using these spring elements in ABAQUS can lead to issues with spring nonlinearity and mismatches between spring stiffness and actual conditions. Specifically, ABAQUS springs cannot simulate the nonlinear changes of ground springs, and it's impossible to set different stiffnesses for springs at different element nodes. Furthermore, for large-scale models, numerous springs need to be created, but the ABAQUS interface can only create springs sequentially, which is extremely time-consuming.

[0028] Therefore, this application uses an external program to perform secondary development on ABAQUS, which can quickly calculate the spring stiffness values ​​of each node in the numerical calculation model and quickly generate keywords to write into ABAQUS to realize the parametric modeling process of nonlinear springs.

[0029] Example 1

[0030] See Figure 1 This application provides a method for modeling nonlinear stratum springs in tunnels, including steps S100, S200, S300 and S400.

[0031] Step S100: Obtain target node information based on the pre-established shield tunnel model. The target node information includes the position information and unit number information of the unit nodes on the outer surface of the shield tunnel.

[0032] Before performing this step, the shield tunnel should be modeled and meshed in ABAQUS based on the various parameter data of the tunnel. After creation, the position information and element number information of the element nodes on the outer surface of the shield tunnel can be obtained.

[0033] Step S200: Based on the target node information, by constraining the model displacement and applying unit pressure to the tunnel surface, the reaction force of its unit node is obtained and the unit area represented by the unit node is calculated to obtain the first dataset, which includes the unit area of ​​the target node.

[0034] In order to export only the reaction force of each target node that is needed in subsequent steps, the exported content needs to be modified in the ABAQUS software:

[0035] First, select the outer surface of the shield tunnel to which the ground spring will be applied, and create a set "Out_Surf" in the "Assembly" level to represent the data of the nodes on the outer surface of the shield tunnel;

[0036] Then, at the "Step" level, adjust "Field output" to output only in the last step "Last increment", and change the output area to output only "Set-Out_Surf". In the "Output Variations" below, only check "RT", that is, set the output data to be the nodal reaction force of the nodes on the outer surface of the shield tunnel.

[0037] After the modification is completed, constrain all displacements of the shield tunnel model, that is, keep all nodes stationary and apply a pressure of unit "1" to the outer surface of the tunnel, submit the calculation to complete, and obtain the nodal reaction forces;

[0038] Use the "Report Field Output" function to export the first dataset "RT_Magnitude" representing the nodal reactions of the outer surface as a .csv file. It should be noted that this export is of nodal reactions, but since the applied load is 1, the nodal reaction is the area of ​​the element represented by the node. The exported .csv file contains the reaction forces of all element nodes in the output set "Report Field Output", that is, the element area of ​​the element node. The exported file also contains element number information and node name, and each node name corresponds to a reaction force data.

[0039] Step S300: Based on the target node information, establish a spring model for each target node. The spring model includes a normal spring, a first tangential spring, and a second tangential spring. The axis of the normal spring is perpendicular to the shield tunnel axis, and the axis of the first tangential spring is parallel to the shield tunnel axis. The axes of the normal spring, the first tangential spring, and the second tangential spring form a left / right-hand coordinate system.

[0040] Specifically, this step requires secondary development of ABAQUS, that is, writing MATLAB code based on the ABAQUS help documentation to generate the corresponding "Spr ng1" nonlinear spring element and linear spring keyword, and setting the spring as follows:

[0041] Step S310: Based on the shield tunnel model, generate a cylindrical coordinate system "CSYS-Spring" whose Z-axis coincides with the shield tunnel axis. The radial distance, azimuth, and height of the cylindrical coordinate system are labeled as ρ, θ, and z, respectively; the Z-axis is the height direction, see [link to documentation]. Figure 2 And obtain the node coordinates of each target node in the cylindrical coordinate system, specifically:

[0042] Based on the shield tunnel model, the axial direction data of the shield tunnel and the three-axis direction data of the basic coordinate system are obtained; the basic coordinate system is the coordinate system automatically preset in ABAQUS. The shield tunnel model is constructed under this coordinate system, and the axial direction of the shield tunnel can be obtained.

[0043] The reference coordinate axis is obtained by comparing the axial direction data with the three-axis direction data of the basic coordinate system. The reference coordinate axis is the coordinate axis in the three axes of the basic coordinate system that coincides with the axial direction of the shield tunnel.

[0044] Based on the direction vector of the reference coordinate axis, generate the Z-direction vector of the cylindrical coordinate system.

[0045] For example, in a shield tunnel model, the tunnel axis is along the Y direction of the basic coordinate system. When constructing the cylindrical coordinate system "CSYS-Spring", its Z-direction positioning code is set to "0.,0.,0.,0.,1.,0.;", which is a vector from "0,0,0" to "0,1,0". The origin of the cylindrical coordinate system can be set at the center of the tunnel.

[0046] Each target node has corresponding coordinates in the cylindrical coordinate system, namely node coordinates, and all node coordinates have the same ρ value.

[0047] Step S320: Construct a surface reference coordinate system (u, v, w) with the node coordinates as the origin. The coordinate axes of the surface reference coordinate system are in a preset positional relationship with the shield tunnel axis, that is, the u axis is perpendicular to the z axis and faces away from the center of the tunnel, the w axis is parallel to the z axis and the two are in the same direction, and the v axis is tangent to the tunnel surface.

[0048] Step S330: Establish a normal spring, a first tangential spring, and a second tangential spring using the three coordinate axes of the surface reference coordinate system as spring axes respectively; that is, construct a normal spring using the u-axis as the spring axis, construct a first tangential spring using the w-axis as the spring axis, and construct a second tangential spring using the v-axis as the spring axis.

[0049] Step S400: Based on the first dataset and preset geological information, nonlinear stiffness data are generated for the normal spring, the first tangential spring, and the second tangential spring to obtain a spring model with nonlinear stiffness. This specifically includes the following steps:

[0050] Step S410: Based on the preset stratum information and spring type, obtain the preset relationship between spring displacement and stratum resistance, and calculate the stratum resistance according to the spring displacement and the relationship.

[0051] The stratigraphic information includes stratigraphic categories. Different stratigraphic types are tested in advance using indoor or field tests. By applying different amounts of deformation, the corresponding stratigraphic resistance is obtained. The amount of deformation represents the spring displacement. A relationship between spring displacement and stratigraphic resistance is constructed for each stratigraphic type and stored for easy retrieval later.

[0052] Obtain the positional relationship information between the spring and the shield tunnel, and classify the spring into normal spring, first tangential spring and second tangential spring based on the positional relationship information;

[0053] Obtain the spring displacement value and determine its sign:

[0054] Since the spring model is constructed based on the coordinate axes of the surface reference coordinate system, the sign of the spring displacement is consistent with the sign of the coordinate axis. That is, it is automatically defined by the system as follows: when the spring moves toward the tunnel axis, the displacement is negative; when the spring moves away from the tunnel axis, the displacement is positive.

[0055] For a normal spring, if the spring displacement value is negative, the value of the ground resistance is set to zero, because a negative spring displacement value represents the separation of the tunnel surface from the ground; if the spring displacement value is positive, the preset relationship between the displacement value and the ground resistance is obtained based on the preset ground information.

[0056] For a tangential spring, the formation resistance corresponding to displacement is never zero. That is, the sign of the displacement value of the tangential spring does not affect its stiffness, so the relationship can be obtained directly.

[0057] Step S420: Read the first dataset "RT_Magnitude", that is, obtain the node area of ​​each node. When the spring deforms (displaces), multiply the corresponding unit area of ​​the spring (calculated from the node reaction force) by the corresponding stratum resistance to obtain the spring reaction force.

[0058] This allows us to obtain the spring reaction force corresponding to each spring displacement value;

[0059] Step S430: Combine the spring displacement and the corresponding spring reaction force to construct the spring stiffness matrix, that is, the spring stiffness is determined by an n x 2 matrix (x... i ,yi The matrix is ​​defined as a matrix composed of x, where x i The reaction force of the spring, y i This represents the spring displacement.

[0060] Since the normal ground spring has the characteristic of being only compressed and not tensile, the spring model constructed in this application has a negative displacement under tension (i.e., the tunnel is separated from the soil), at which time the spring should have no stiffness, making the corresponding ground resistance 0; under compression (i.e., the tunnel is squeezing the soil), the displacement is positive, at which time the spring has stiffness.

[0061] Based on the above embodiments, the method of this application further includes step S500:

[0062] Generate a unique spring name for the spring model based on the name information of the target node, and record the target node element number corresponding to the spring model; that is, read the “Part InstanceName” and “NodeLabel” of each node in the generated .csv file to name the nonlinear formation spring;

[0063] The second dataset is obtained by summarizing the spring models, including spring names and stiffness matrices, and the corresponding target node element numbers.

[0064] Specifically, the second dataset will be output as a .txt file;

[0065] Output the shield tunnel model as an .inp file containing model keywords;

[0066] Locate the line "*End Assembly" in the .inp file, and add "*IncLUDE,In NPUT=(filename).TXT" to the line above it. Note that the .txt file and the .inp file should be in the same working directory. Save the modified .inp file.

[0067] Load the shield tunnel model, and the modified .inp file will automatically import the second dataset during the ABAQUS import process as a model;

[0068] ABAQUS establishes an assembly relationship between the spring model and the shield tunnel model by matching the element number and matching the spring name with the target node name, thus obtaining a shield tunnel model with nonlinear stratum springs.

[0069] The method provided in this application can quickly and in batches construct ground springs for shield tunnel models. Compared with existing modeling methods that require defining ground springs sequentially, this invention can save a lot of modeling time.

[0070] Example 2

[0071] See Figure 3 This application also provides a tunnel nonlinear stratum spring modeling system, comprising:

[0072] The first acquisition module 400 is used to acquire target node information based on a pre-established shield tunnel model. The target node information includes the position information and unit number information of the unit nodes on the outer surface of the shield tunnel.

[0073] The second acquisition module 500 is used to obtain the unit node reaction force and calculate the unit area represented by the unit node based on the target node information by constraining the model displacement and applying unit pressure to the tunnel surface, thereby obtaining a first dataset, the first dataset including the unit area of ​​the target node.

[0074] The first construction module 600 is used to build a spring model for each target node based on the target node information. The spring model includes a normal spring, a first tangential spring, and a second tangential spring. The axis of the normal spring is perpendicular to the shield tunnel axis, and the axis of the first tangential spring is parallel to the shield tunnel axis. The axes of the normal spring, the first tangential spring, and the second tangential spring form a left / right-hand coordinate system.

[0075] The first generation module 700 is used to generate nonlinear stiffness data for the normal spring, the first tangential spring, and the second tangential spring based on the first dataset and preset stratum information, so as to obtain a spring model with nonlinear stiffness.

[0076] As an optional implementation, the first construction module 600 includes:

[0077] The first building unit 610 is used to generate a cylindrical coordinate system with the Z-axis coinciding with the shield tunnel axis based on the shield tunnel model, and to obtain the node coordinates of each target node in the cylindrical coordinate system.

[0078] The second construction unit 620 is used to construct a surface reference coordinate system with the node coordinates as the origin, and the coordinate axes of the surface reference coordinate system are in a preset positional relationship with the shield tunnel axis.

[0079] The third building unit 630 is used to establish a normal spring, a first tangential spring, and a second tangential spring, respectively, with the three coordinate axes of the surface reference coordinate system as spring axes.

[0080] As an optional implementation, the first generation module 700 includes:

[0081] The first calculation unit 710 is used to obtain the relationship between spring displacement and formation resistance based on preset formation information, and to calculate the formation resistance based on the spring displacement and the relationship.

[0082] The second calculation unit 720 is used to multiply the unit area in the first dataset by the formation resistance to obtain the spring reaction force;

[0083] The first generation unit 730 is used to combine the spring displacement and the corresponding spring reaction force to construct the spring stiffness matrix.

[0084] As an optional implementation, the target node information further includes name information, and the first generation module 700 further includes:

[0085] The second generation unit 740 is used to generate a unique corresponding spring name for the spring model based on the name information of the target node, and record the target node unit number corresponding to the spring model.

[0086] The third generation unit 750 is used to summarize the spring model, including the spring name and stiffness matrix, and the corresponding target node unit number to obtain the second dataset;

[0087] The first loading unit 760 is used to load the shield tunnel model and import it into the second dataset;

[0088] The fourth building unit 770 is used to establish an assembly relationship between the spring model and the shield tunnel model by matching the unit number and matching the spring name with the target node name, thereby obtaining a shield tunnel model with nonlinear stratum springs.

[0089] Based on the method of Embodiment 1, this embodiment also provides a computer program product, including a computer program that, when executed by a processor, implements the method shown in steps S100 to S400 above.

[0090] Based on the method of Embodiment 1, this embodiment also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method shown in steps S100 to S400 above.

[0091] Based on this understanding, the technical solution of this application can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (such as CD-ROM, USB flash drive, mobile hard drive, etc.) and includes several instructions to cause a computer device (such as personal computer, server, or network device, etc.) to execute the methods of various implementation scenarios of this application.

[0092] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0093] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for modeling nonlinear ground springs in tunnels, characterized in that, include: Target node information is obtained based on a pre-established shield tunnel model. The target node information includes the location information and unit number information of the unit nodes on the outer surface of the shield tunnel. Based on the target node information, the reaction force of the unit node is obtained by constraining the model displacement and applying unit pressure to the tunnel surface, and the unit area represented by the unit node is calculated to obtain the first dataset, which includes the unit area of ​​the target node. Based on the shield tunnel model, a cylindrical coordinate system with the Z-axis coinciding with the shield tunnel axis is generated, and the node coordinates of each target node in the cylindrical coordinate system are obtained. A surface reference coordinate system is constructed with the node coordinates as the origin, and the coordinate axes of the surface reference coordinate system are in a preset positional relationship with the shield tunnel axis; A normal spring, a first tangential spring, and a second tangential spring are established with the three coordinate axes of the surface reference coordinate system as spring axes, respectively; the axis of the normal spring is perpendicular to the shield tunnel axis, and the axis of the first tangential spring is parallel to the shield tunnel axis. The axes of the normal spring, the first tangential spring, and the second tangential spring form a left / right-hand coordinate system. Based on the preset stratum information and spring type, the preset relationship between spring displacement and stratum resistance is obtained, and the stratum resistance is calculated based on the spring displacement and the relationship. The spring reaction force is obtained by multiplying the cell area in the first dataset by the formation resistance. By combining the spring displacement and the corresponding spring reaction force, the stiffness matrix of the spring is constructed, resulting in a spring model with nonlinear stiffness.

2. The method for modeling tunnel nonlinear strata springs according to claim 1, characterized in that, The target node information also includes name information, and the method further includes: Generate a unique spring name for the spring model based on the name information of the target node, and record the target node element number corresponding to the spring model; The second dataset is obtained by summarizing the spring models, including spring names and stiffness matrices, and the corresponding target node element numbers. Load the shield tunnel model and import it into the second dataset; By matching the unit number and matching the spring name with the target node name, the spring model and the shield tunnel model are assembled to obtain a shield tunnel model with nonlinear stratum springs.

3. The method for modeling tunnel nonlinear strata springs according to claim 1, characterized in that, Based on preset formation information and spring type, obtain the preset relationship between spring displacement and formation resistance, including: Obtain the positional relationship information between the spring and the shield tunnel, and classify the spring into normal spring, first tangential spring and second tangential spring based on the positional relationship information; Obtain the spring displacement and determine the sign of the spring displacement value: For a normal spring, if the spring displacement value is negative, the formation resistance value is set to zero; if the spring displacement value is positive, the preset relationship between the displacement value and the formation resistance is obtained based on the preset formation information.

4. The method for modeling tunnel nonlinear strata springs according to claim 1, characterized in that, The shield tunnel model includes basic coordinate axes; The generation of a cylindrical coordinate system based on the shield tunnel model, with the Z-axis coinciding with the shield tunnel axis, includes: Based on the shield tunnel model, obtain the axial direction data of the shield tunnel and the three-axis direction data of the basic coordinate system; The reference coordinate axis is obtained by comparing the axial direction data with the three-axis direction data of the basic coordinate system. The reference coordinate axis is the coordinate axis in the three axes of the basic coordinate system that coincides with the axial direction of the shield tunnel. Based on the direction vector of the reference coordinate axis, generate the Z-direction vector of the cylindrical coordinate system.

5. A tunnel nonlinear stratum spring modeling system, characterized in that, include: The first acquisition module is used to acquire target node information based on a pre-established shield tunnel model. The target node information includes the position information and unit number information of the unit nodes on the outer surface of the shield tunnel. The second acquisition module is used to obtain the unit node reaction force and calculate the unit area represented by the unit node based on the target node information by constraining the model displacement and applying unit pressure to the tunnel surface, thereby obtaining a first dataset, which includes the unit area of ​​the target node. The first construction module is used to build a spring model for each target node based on the target node information. The spring model includes a normal spring, a first tangential spring, and a second tangential spring. The axis of the normal spring is perpendicular to the shield tunnel axis, and the axis of the first tangential spring is parallel to the shield tunnel axis. The axes of the normal spring, the first tangential spring, and the second tangential spring form a left / right-hand coordinate system. The first building module includes: The first building unit is used to generate a cylindrical coordinate system with the Z-axis coinciding with the shield tunnel axis based on the shield tunnel model, and to obtain the node coordinates of each target node in the cylindrical coordinate system. The second construction unit is used to construct a surface reference coordinate system with the node coordinates as the origin, and the coordinate axes of the surface reference coordinate system are in a preset positional relationship with the shield tunnel axis. The third construction unit is used to establish a normal spring, a first tangential spring, and a second tangential spring, respectively, with the three coordinate axes of the surface reference coordinate system as spring axes; The first generation module is used to generate nonlinear stiffness data for the normal spring, the first tangential spring and the second tangential spring based on the first dataset and the preset stratum information, so as to obtain a spring model with nonlinear stiffness. The first generation module includes: The first calculation unit is used to obtain the relationship between spring displacement and formation resistance based on preset formation information, and to calculate the formation resistance based on the spring displacement and the relationship. The second calculation unit is used to multiply the unit area in the first dataset by the formation resistance to obtain the spring reaction force; The first generating unit is used to combine the spring displacement and the corresponding spring reaction force to construct the spring stiffness matrix.

6. The tunnel nonlinear stratum spring modeling system according to claim 5, characterized in that, The target node information also includes name information, and the first generation module further includes: The second generation unit is used to generate a unique corresponding spring name for the spring model based on the name information of the target node, and record the target node unit number corresponding to the spring model. The third generation unit is used to summarize the spring model, including the spring name and stiffness matrix, and the corresponding target node element number to obtain the second dataset; The first loading unit is used to load the shield tunnel model and import it into the second dataset; The fourth building unit is used to establish an assembly relationship between the spring model and the shield tunnel model by matching the unit number and matching the spring name with the target node name, so as to obtain a shield tunnel model with nonlinear stratum spring.

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