A Shield Machine Tunnel Excavation Simulation Method Based on ABAQUS

Abstract

The present invention discloses a shield tunneling excavation simulation method based on ABAQUS. By using the birth and death element method of ABAQUS, in the assembly module, the grouting layer, lining and shield body required in the whole construction process are assembled into the simulation model. Then, in the interaction module, by setting Modelchange contacts for the excavated soil, grouting layer, lining and shield body, and removing and activating them in the corresponding analysis steps, the process of shield machine propulsion and support in the actual tunnel construction can be simulated, and the stress condition of the shield body during the construction propulsion process can be accurately obtained. Moreover, compared with simulation methods such as the transient method and the discrete element method, the simulation method proposed by the present invention can efficiently and quickly implement the complete shield construction simulation process, and can import the real geological environment model established based on geological exploration data for coupled simulation, so as to obtain the stress and load conditions of the shield body in the whole geological construction process.

Description

Technical Field

[0001] The present invention relates to the field of shield tunneling simulation, and more particularly to a shield tunneling simulation method based on ABAQUS. Background Art

[0002] In recent years, the infrastructure construction in China has developed rapidly. Projects such as railways, subways, highways, and urban underground utility tunnels are continuously planned, constructed, and under construction. Shield machines, as the most important special machinery for tunnel boring, are widely used, especially in the construction of urban subways and underground utility tunnels. However, the current R & D design methods for shield machines are not yet mature, and there are still many deficiencies in the simulation analysis of shield tunneling.

[0003] In the prior art: 1. In geotechnical engineering, ABAQUS is often used to simulate tunnel excavation. However, this type of simulation focuses on the settlement, pore pressure of the soil, and the stability analysis of tunnel support during the tunnel excavation process. The shield body is mostly simplified into a simple shell, and the stress condition of the shield body during the excavation process cannot be truly obtained; 2. In the field of mechanical engineering, for the simulation analysis of the shield body strength, there are currently two main methods. The first is the finite element method, which conducts constraint and loading analysis on the shield machine under specific working conditions through engineering experience. This method is relatively effective for the simulation analysis of individual components. However, for the overall shield machine, due to the variability and non-uniformity of soil types in the real geological environment, the constraints and loads on the shield body are variable and complex, making it difficult to simulate the real working conditions; The second is the discrete element method, which simultaneously establishes the shield machine and soil models for simulation analysis. The discrete element method focuses on the movement and stress conditions of granular bodies. The shield body is modeled as a rigid body. If the stress condition of the shield body needs to be known, it is necessary to perform coupled simulation with finite element software. This method is time-consuming in calculation, and structures such as segments and grouting layers are not modeled, and the complete shield tunneling process cannot be reproduced.

[0004] In summary, there is an urgent need for a shield tunneling simulation method based on ABAQUS to solve the problems of incomplete modeling of the shield body and inaccurate stress condition in the prior art. Summary of the Invention

[0005] The purpose of the present invention is to provide a shield tunneling simulation method based on ABAQUS to solve the problems of incomplete modeling of the shield body and inaccurate stress condition in the prior art. The specific technical solutions are as follows:

[0006] A shield tunneling simulation method based on ABAQUS includes the following steps:

[0007] Step S1: Create a three-dimensional model of shield tunneling and assemble the three-dimensional model into the simulation model of ABAQUS;

[0008] Step S2: Create analysis steps and contact properties based on the simulation model;

[0009] Step S3: Create loads and boundary conditions;

[0010] Step S4: Calculate and post-process the analysis to obtain the simulation results.

[0011] Preferably, the above technical solution, the step S1 includes:

[0012] Step S1.1: Create model components, including the shield body, soil mass, grouting layer, and lining;

[0013] Step S1.2: Create material properties, and create corresponding material properties for the soil mass, shield body, grouting layer, and lining;

[0014] Step S1.3: Model assembly, assemble the model components into the simulation model.

[0015] Preferably, in the above technical solution, in the step S1.1, the shield body includes a structure body, a cutter head, the soil inside the cutter head, and the soil inside the soil pressure chamber.

[0016] Preferably, the above technical solution, the step S2 includes:

[0017] Step S2.1: Create analysis steps. Initially create a GeoStatic analysis step for initial in-situ stress balance of geotechnical engineering. For the subsequent tunneling process, use the distance of one lining as one tunneling step to conduct shield tunneling simulation, and each tunneling step is realized by two simulation analysis steps step;

[0018] Step S2.2: Create a connector, use the connector to simulate the shield tunneling cylinder, and use the flexible coupling in ABAQUS to couple the action area of the shield tunneling cylinder to the control point;

[0019] Step S2.3: Based on ABAQUS, perform birth-death element settings for the shield body, excavated soil mass, grouting layer, and lining;

[0020] Step S2.4: Create contact relationships for each component of the simulation model.

[0021] Preferably, in the above technical solution, in the step S2.2, the type of the connector is set to Translate translational pair.

[0022] Preferably, the above technical solution, the step S2.3 includes:

[0023] Step S2.31: Under the initial GeoStatic analysis step, create Model change contact properties for all linings, grouting layers, shields, and connectors, and select Deactivated in this step to remove all components except the soil mass.

[0024] Step S2.32: After the shield excavation and before the shield completely enters the soil mass, in the first analysis step of each excavation step, remove the excavated soil with a lining length in front of the shield and the shield activated in the previous excavation step, and then activate the shield of this excavation step. In the second analysis step, continue the settings of the first analysis step, and cycle through K1 excavation steps in this way until the shield completely enters the soil mass.

[0025] Step S2.33: After the shield completely enters the soil mass, in the first analysis step of each excavation step, remove the excavated soil in front of the shield, the shield and the connector activated in the previous excavation step, then activate the shield, lining, and connector of this excavation step, and generate a grouting layer between the lining activated in the previous excavation step and the soil mass. In the second analysis step, continue this setting, and cycle through K2 excavation steps in this way.

[0026] Preferably, the above technical solution, the step S3 includes:

[0027] Step S3.1: Create boundary conditions:

[0028] 1), Do not constrain the upper boundary of the soil mass, and restrict the normal displacement of the other 5 faces.

[0029] 2), For the lining and grouting layer, restrict the normal displacement of the end face closest to the soil mass boundary on the outermost side.

[0030] 3), For the shield, there are two cases:

[0031] Before starting tunneling and before the shield completely enters the soil mass, create a fixed constraint for the shield in the first analysis step of each excavation step to enable the shield to contact the rock and soil smoothly, and set Deactivated in the first analysis step of the next excavation step to release the constraint of the shield.

[0032] After the shield completely enters the soil mass, set a fixed constraint for the shield in the first analysis step of each excavation step, set Deactivated to release the constraint in the second analysis step, and create a displacement in the tunneling direction of the shield for the connector in this analysis step to achieve the tunneling propulsion effect on the shield.

[0033] Step S3.2: Create loads:

[0034] 1), Set the gravity action on the entire simulation model.

[0035] 2) Starting from the activation of each grouting layer, a predefined field of materials with different elastic moduli is set for the grouting layer for K3 tunneling steps to simulate the solidification and hardening process of the grouting layer;

[0036] 3) For the inner surface of the excavated soil body, a grouting pressure of M atmospheres is set according to the construction parameters and maintained until the next tunneling step when Deactivated is set to remove the grouting pressure.

[0037] Preferably, in the above technical solution, in step S4, the simulation results include the stress condition of the shield body and the propelling force of the shield body.

[0038] Applying the technical solution of the present invention has the following beneficial effects:

[0039] (1) The shield tunneling excavation simulation method based on ABAQUS of the present invention uses the birth and death element method of ABAQUS. In the assembly module, the grouting layer, lining, and shield body required in the entire construction process are assembled into the simulation model, and then in the interaction module, Model change contacts are set for the excavated soil body, grouting layer, lining, and shield body, and removed and activated in the corresponding analysis steps, which can simulate the shield propulsion and support processes in the real tunnel construction process, accurately obtain the stress conditions during the shield construction propulsion process, and compared with transient methods and discrete element simulation methods, etc., the simulation method proposed by the present invention can efficiently and quickly realize the complete shield construction simulation process, and can import the real geological environment model established based on geological exploration data for coupled simulation, so as to obtain the stress and load conditions of the shield body in the whole geological construction process.

[0040] (2) In the method of the present invention, a complete model of the shield body is established, and the stress conditions during the shield construction propulsion process can be obtained preferably.

[0041] (3) The method of the present invention uses a connector to simulate the cylinder propulsion, which greatly simplifies the simulation model and improves the simulation efficiency on the premise of ensuring the calculation accuracy.

[0042] (4) The method of the present invention uses the birth and death element method of ABAQUS, and by removing and activating the grouting layer, lining, and shield body, the shield propulsion and support in the real tunnel construction process can be simulated.

[0043] In addition to the purposes, features, and advantages described above, the present invention has other purposes, features, and advantages. The present invention will be further described in detail below with reference to the drawings. Description of the Drawings

[0044] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0045] In the accompanying drawings:

[0046] Figure 1 are the components of the simulation model in this embodiment, (a) schematically shows the shield body, (b) schematically shows the soil body, (c) schematically shows the grouting layer, and (d) schematically shows the lining;

[0047] Figure 2 is the overall assembly drawing of the simulation model in this embodiment;

[0048] Figure 3 is Figure 2 the enlarged view of A in;

[0049] Figure 4 is the flow chart of the simulation analysis steps in this embodiment (schematically showing before the shield body enters the soil body and after it completely enters the soil body);

[0050] Figure 5 is the schematic diagram of the contact relationship attributes in this embodiment;

[0051] Figure 6 is the schematic diagram of the simulated oil cylinder of the connector between the lining and the shield body in this embodiment;

[0052] Figure 7 is the schematic diagram of the model boundary conditions and loads in this embodiment;

[0053] Figure 8 is the post-processing nephogram in this embodiment, (a) schematically shows the displacement nephogram of the model, (b) is the stress nephogram of the model, and (c) schematically shows the contact stress nephogram of the cutter head;

[0054] Wherein, 1. Shield body; 1.1. Structural body; 1.2. Cutter head; 2. Soil body (rock and soil); 2.1. Excavated soil body; 2.2. Surrounding soil body; 3. Grouting layer; 4. Lining; 5. Connector. Specific embodiments

[0055] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention can be implemented in many different ways defined and covered by the claims.

[0056] Embodiment:

[0057] In this embodiment, a shield tunneling excavation simulation method based on ABAQUS is disclosed. The general idea of this simulation method is as follows, as Figures 1 to 8 shown:

[0058] 1. For the simulation model, four components are created, namely the geotechnical body (i.e., soil body 2), the shield body 1, the grouting layer 3, and the lining 4, as Figure 1 shown. Among them, the shield body models the structure body, the cutter head, the soil in the soil pressure chamber, and the soil in the cutter head. Since the lining is not the focus of the simulation, in order to simplify the model, instead of modeling it in a segmented manner as in reality, a complete propulsion ring is established.

[0059] 2. The oil cylinder propulsion is simulated using a connector. Set the type of the connector as a Translate translational pair, and add the displacement in the shield propulsion direction to the connector in the load setting module, then the oil cylinder propulsion process can be simulated.

[0060] 3. In the contact module, create Model change contact properties for the lining, the grouting layer, the shield body, the connector, and the excavated soil body (i.e., the soil body that needs to be excavated) respectively, so that they are removed and activated in the corresponding analysis step, thereby simulating and reproducing the complete shield tunneling process.

[0061] Specifically, the simulation method in this embodiment includes steps S1 to S4, which are as follows:

[0062] Step S1: Create a three-dimensional model of shield excavation and assemble the three-dimensional model into the simulation model of ABAQUS. Step S1 specifically includes steps S1.1 to S1.3, as follows:

[0063] Step S1.1: Create model components, including the shield body 1, the soil body 2, the grouting layer 3, and the lining 4, that is, based on ABAQUS, create four components of the soil body, the shield body, the grouting layer, and the lining in the part (Chinese annotation: component) module;

[0064] The soil body 2 consists of the surrounding soil body 2.2 and the excavated soil body 2.1. In order to avoid the influence of boundary effects and at the same time simulate the buried depth condition of the actual shield excavation construction, the modeling size of the soil body is 240 * 150 * 80 m;

[0065] The shield body models the structure body, the cutter head, the soil in the soil pressure chamber, and the soil in the cutter head, that is, the shield body 1 includes the structure body 1.1, the cutter head 1.2, the soil in the cutter head (not labeled), and the soil in the soil pressure chamber (not labeled). The soil in the cutter head is arranged in the cutter head, and the soil in the soil pressure chamber is arranged in the soil pressure chamber (i.e., the structure body). Here, the connection relationship of each component of the shield body is common knowledge in the art, and this embodiment will not elaborate too much; the outer diameter of the shield body end is 6.66 m, the outer diameter of the tail end is 6.5 m, and the length is 9 m;

[0066] The lining is not the focus of the simulation, and the model is simplified. The actual segmented assembled lining is built into a complete lining ring, with an outer diameter of 6.4 m, a thickness of 0.35 m, and a width of 1.5 m;

[0067] The modeling dimensions of the grouting layer are an outer diameter of 6.66 m, a thickness of 0.13 m, and a width of 1.5 m;

[0068] It should be noted that for the shield propulsion cylinders, the connector is used in this simulation model for simulation (the connector is created in the subsequent interaction module).

[0069] Step S1.2: Create material properties, and create corresponding material properties for the soil body, shield body, grouting layer, and lining as follows:

[0070] Search for data to create corresponding material properties for the shield body, grouting layer, lining, and geotechnical soil (i.e., soil body). The cross-sectional properties are all set to solid homogeneous. Among them, for the soil constitutive model, the most commonly used Coulomb-Mohr model in engineering is selected. For the construction section to which the simulation model corresponds, the geotechnical type is a single argillaceous siltstone layer, and the geotechnical parameters are set according to geotechnical tests.

[0071] Step S1.3: Model assembly, assemble the model components into the simulation model as follows:

[0072] The ABAQUS element birth and death method is used in the simulation model. All components required for the simulation need to be assembled into the simulation model in advance. Among them, as Figure 2 and Figure 3 shown, the simulation takes one tunneling ring as one propulsion step, and for each propulsion step, the corresponding shield body, lining, and grouting layer need to be assembled.

[0073] Step S2: Create analysis steps and contact properties based on the simulation model. Step S2 includes steps S2.1 to S2.4, as Figure 4 and Figure 6 shown, as follows:

[0074] Step S2.1: Create analysis steps. Initially, create a geostress analysis step to balance the initial geostress of the geotechnical soil. For the subsequent tunneling process, the shield propulsion simulation is carried out with the distance of one lining as one tunneling step. Each tunneling step is realized by two simulation analysis steps step. Specifically:

[0075] The shield tunneling simulation proposed by the simulation method of this embodiment includes three processes: the initial state, before the shield body enters the soil mass, and after the shield body enters the soil mass. Initially, a GeoStatic (Chinese annotation: in-situ stress) analysis step is set, large geometric deformation is turned off, the increment step is set to an automatic increment step, and other parameters are kept at their default settings. The in-situ stress balance of the soil mass is carried out so that in the initial state of the soil mass, the stress is the true stress distribution under the action of gravity, and the maximum displacement is close to 0. After carrying out the in-situ stress balance of the soil mass, in the subsequent shield tunneling process, the shield is advanced for simulation with a distance of 1.5 m of one lining ring as one tunneling step, and each tunneling step is realized by two simulation analysis steps step.

[0076] Since the shield tunneling process in this method is quasi-static, the analysis step of the tunneling process adopts a static general analysis step, large geometric deformation is turned off, the initial increment step is changed to 0.5, and other parameters are kept at their default settings. In the simulation method of this embodiment, the shield body has tunneled 100 tunneling steps, so 200 static general simulation analysis steps step need to be created.

[0077] Step S2.2, as Figure 6 shown, create a connector, use the connector to simulate the shield propulsion cylinder, and couple the action area of the shield propulsion cylinder to the control point by using the flexible coupling in ABAQUS as follows:

[0078] There are 24 shield propulsion cylinders distributed circumferentially in the actual shield model. The cylinder barrels are fixed on the shield body, and the tail ends of the piston rods are pressed against the latest ring of lining to realize the propulsion of the shield machine. To simplify the simulation model, the simulation method of this embodiment uses a connector to simulate the shield propulsion cylinder. In engineering practice, the shield machine usually divides the circumferentially distributed cylinders into 4 area groups for easy control. To simplify the number of cylinders, the end face of the lining opposite to the shield body and the cylinder action area on the shield body are divided into 4 blocks according to the cylinder zoning. Reference points are created at the centers of each area as the coupling control points, and the corresponding cylinder action areas are coupled to the control points. A connector for simulating the cylinder is created between the coupling control points corresponding to the lining and the shield body. The action of the cylinder on the shield body is horizontal propulsion, so the type of the connector is set as a Translate translational pair.

[0079] Step S2.3: Based on ABAQUS, perform the birth and death element settings for the components, that is, perform the birth and death element settings for the shield body, the soil to be excavated, the grouting layer, and the lining. Among them, in the interaction (Chinese annotation: contact) module, the Model change attribute can be set for the set, and by selecting Deactivated in this step (Chinese annotation: deactivated in this analysis step) or Reactivated in this step (Chinese annotation: activated in this analysis step), the selected set can be removed or activated in the corresponding analysis step. This is the birth and death element function of ABAQUS. This step S2.3 includes steps S2.31 to S2.33, as Figure 4 shown below:

[0080] Step S2.31: In the initial GeoStatic analysis step, create the Model change contact attribute for all lining rings, grouting layers, shield bodies, and connectors, and select Deactivated in this step to remove all components except the soil.

[0081] After the shield body is excavated, in the first K1 excavation steps, the shield body has not completely entered the soil. Therefore, in the first analysis step of each excavation step, only the excavated soil with a lining length (i.e., 1.5 m) in front of the shield body and the shield body activated in the previous excavation step (if it is the first excavation step, this operation is not required) need to be removed, and then the shield body of this excavation step can be activated. The second analysis step continues the settings of the first analysis step to the next excavation step, and this cycle is repeated for K1 excavation steps until the shield body completely enters the soil. In this step, K1 is equal to 5.

[0082] After the shield body completely enters the soil, in the first analysis step of each excavation step, the excavated soil in front of the shield body and the shield body and connectors activated in the previous excavation step are removed, and then the shield body, lining, and connectors of this excavation step are activated, and a grouting layer is generated between the lining activated in the previous excavation step and the soil. The second analysis step continues the settings to the next excavation step, and this cycle is repeated for K2 excavation steps; in this step, K2 is equal to 95.

[0083] Step S2.4: Create the contact relationships for the components of the simulation model, specifically as follows:

[0084] In the simulation model of this embodiment, there are interaction relationships between the grouting layer and the excavated soil, between the grouting layer and the lining, between the shield and the excavated soil, between the rings of the lining, and between the rings of the grouting layer. Among them, the grouting layer and the lining are mainly used for tunnel support in the model and there is no complex relative movement. Therefore, bonding relationships are set between the grouting layers, between the linings, between the grouting layer and the rock and soil, and between the grouting layer and the lining. The shield is the key component of the simulation, and contact properties are set between its end face and circumferential surface and the rock and soil (as Figure 5 shown, that is, the inner surface of the surrounding soil).

[0085] Step S3, create loads and boundary conditions. Step S3 includes Step S3.1 and Step S3.2, as follows:

[0086] Step S3.1, create boundary conditions, as Figure 7 shown:

[0087] 1), Do not constrain the upper boundary of the soil, and restrict the normal displacement of the other 5 faces;

[0088] 2), For the lining and the grouting layer, restrict the normal displacement of the end face closest to the soil boundary on the outermost side (that is, the end face at the very end away from the cutter head);

[0089] 3), For the shield, there are two cases:

[0090] Before starting tunneling but before the shield completely enters the soil, create a fixed constraint for the shield in the first analysis step of each tunneling step to enable the shield to contact the rock and soil smoothly, and release the constraint of the shield by setting Deactivated (Chinese annotation: invalidated) in the first analysis step of the next tunneling step;

[0091] After the shield completely enters the soil, create a fixed constraint for the shield in the first analysis step of each tunneling step, release the constraint by setting Deactivated in the second analysis step, and create a displacement in the tunneling direction of the shield for the connector in this analysis step to achieve the tunneling propulsion effect on the shield.

[0092] Step S3.2, create loads:

[0093] 1), Set the gravity action for the entire simulation model, and the magnitude of the gravitational acceleration is -9.81 m / s2;

[0094] 2), For each grouting layer starting from activation, set a material predefined field with different elastic moduli for the grouting layer for K3 tunneling steps to simulate the solidification and hardening process of the grouting layer; in this embodiment, K3 is equal to 5;

[0095] 3) Set the grouting pressure of M atmospheres according to the construction parameters on the inner surface of the soil body after excavation, and continue until the next excavation step to set Deactivated to remove the grouting pressure. In this embodiment, M is equal to 3.

[0096] Step S4, perform calculation and post-processing analysis to obtain the simulation results. As Figure 8 shown, the simulation results include the stress condition of the shield body and the propelling force of the shield body, specifically as follows:

[0097] Create a job for the established model and submit it for calculation. After the calculation is completed, the tunneling process of the shield and the stress condition of the shield body at each excavation step can be displayed in the post-processing module; the propelling force of the shield body can be obtained by extracting the nodal force NFORC2 in the tunneling direction on the connector.

[0098] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A shield tunneling excavation simulation method based on ABAQUS, characterized in that, It includes the following steps: Step S1: Create a 3D model of shield tunneling and assemble the 3D model into the simulation model of ABAQUS; Step S2: Create analysis steps and contact properties based on the simulation model; Step S3: Create loads and boundary conditions; Step S4: Calculate and post-process the analysis to obtain the simulation results; The said Step S1 includes: Step S1.1: Create model components, including the shield body (1), soil mass (2), grouting layer (3), and lining (4); Step S1.2: Create material properties and create corresponding material properties for the soil mass, shield body, grouting layer, and lining; Step S1.3: Model assembly, assemble the model components into the simulation model; The said Step S2 includes: Step S2.1: Create analysis steps. Initially, create a geostatic stress analysis step to perform initial geostatic stress balance on the rock and soil. For the subsequent tunneling process, use the distance of one lining as one tunneling step to conduct shield tunneling simulation, and each tunneling step is implemented by two simulation analysis steps (step); Step S2.2: Create a connector (5), use the connector to simulate the shield propulsion cylinder, and apply the flexible coupling in ABAQUS to couple the action area of the shield propulsion cylinder to the control point; Step S2.3: Based on ABAQUS, perform birth and death element settings for the shield body, excavated soil mass, grouting layer, and lining; Step S2.4: Create contact relationships for each component of the simulation model; The said Step S2.3 includes: Step S2.31: Under the initial GeoStatic analysis step, create Model change contact properties for all linings, grouting layers, shield bodies, and connectors, and select Deactivated in this step to remove all components except the soil mass; Step S2.32: After the shield body is excavated and before it fully enters the soil mass, in the first analysis step of each excavation step, the excavated soil with a lining length in front of the shield body and the shield body activated in the previous excavation step are removed, and then the shield body of this excavation step is activated. The settings of the first analysis step are continued in the second analysis step, and so on excavation steps until the shield body fully enters the soil mass; Step S2.33: After the shield body completely enters the soil mass, in the first analysis step of each excavation step, the excavated soil in front of the shield body and the shield body and connectors activated in the previous excavation step are removed, then the shield body, lining and connectors of the current excavation step are activated, and a grouting layer is generated between the lining activated in the previous excavation step and the soil mass. The settings of the first analysis step of this step are continued in the second analysis step, and so on in a cycle. excavation steps.

2. The shield tunneling excavation simulation method based on ABAQUS according to claim 1, characterized in that In the said Step S1.1, the shield body (1) includes a structural body (1.1), a cutter head (1.2), the soil inside the cutter head, and the soil inside the soil pressure chamber.

3. The shield tunneling excavation simulation method based on ABAQUS according to claim 1, characterized in that In the said Step S2.2, the type of the connector is set to Translate translational pair.

4. The shield tunneling excavation simulation method based on ABAQUS according to claim 1, characterized in that The said Step S3 includes: Step S3.1: Create boundary conditions: 1) Do not constrain the upper boundary of the soil mass, and restrict the normal displacements of the other five faces; 2) For the lining and grouting layer, restrict the normal displacement of the end face closest to the soil mass boundary on the outermost side; 3) For the shield body, there are two cases: Before starting tunneling and before the shield body completely enters the soil mass, create a fixed constraint for the shield body in the first analysis step of each tunneling step to enable the shield body to contact the rock and soil smoothly, and set Deactivated in the first analysis step of the next tunneling step to release the constraint of the shield body; After the shield body completely enters the soil mass, create a fixed constraint for the shield body in the first analysis step of each tunneling step, set Deactivated to release the constraint in the second analysis step, and create a displacement in the tunneling direction of the shield body for the connector in this analysis step to realize the tunneling propulsion effect on the shield body; Step S3.2: Create loads: 1) Set the gravity action on the entire simulation model; 2), starting from activation for each grouting layer, continuously set predefined fields of materials with different elastic moduli for the grouting layer for tunneling steps to simulate the solidification and hardening process of the grouting layer; 3), for the inner surface of the soil after excavation, set the grouting pressure of atmospheric pressure and continue until the next excavation step to set Deactivated to remove the grouting pressure.

5. The shield tunneling excavation simulation method based on ABAQUS according to claim 1, wherein In the said Step S4, the simulation results include the force condition of the shield body and the propulsion force of the shield body.

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