An opensees-based simulation method for dynamic interaction between shield tunnel and soil

Abstract

The application discloses a shield tunnel-soil dynamic interaction simulation method based on OpenSees, and comprises the following steps: S1, setting boundary conditions, and establishing a tunnel-soil dynamic interaction finite element model; S2, performing gravity analysis on the tunnel-soil dynamic interaction finite element model; S3, performing zero-clearing processing on soil displacement; S4, adding shield tunnel segment, joint bolt and compression-resistant rubber gasket material unit and material information, and setting a contact surface between the tunnel and the soil; S5, binding a nonlinear beam unit based on a fiber section to the segment unit, and simulating nonlinear characteristics of the segment; S6, converting soil properties from linear elasticity to elastoplasticity; and S7, performing incremental dynamic analysis on the model, adopting an initial stress field of the soil as an initial state, and applying seismic excitation to the bottom of the model; and the application predicts and evaluates the anti-seismic capacity of the tunnel through the shield tunnel seismic response refined numerical modeling and calculation method.

Description

Technical Field

[0001] This invention relates to the technical field of tunnel soil safety, and specifically to a method for simulating the dynamic interaction between shield tunnels and soil based on OpenSees. Background Technology

[0002] Existing tunnel-soil interaction models primarily use the finite element method to establish a two-dimensional model under the assumption of plane strain. This often involves using several solid elements to simulate soil layers, beam elements to simulate bending structures such as tunnel segments, and column elements to simulate compression structures such as pile foundations. Alternatively, a three-dimensional model can be established, with the tunnel structure simulated using an elastic model.

[0003] Actual tunnel structures under soil compressive stress are not simple bending members; their nonlinear properties must be considered, along with the interaction between soil pressure and the lining. Most existing models fail to account for the lateral connections between lining segments and the longitudinal connections between segment rings. They treat the stress-strain responses of each soil layer and lining material as varying within an elastic range, and consider the tunnel structure as an equivalent integral ring. The focus is on the overall dynamics and deformation of the tunnel, neglecting the influence of the joint structure, as the most vulnerable part of the tunnel, on the stress distribution. In tunnel-soil interaction models studying liquefiable strata, most models fail to consider the nonlinear properties of the segments and the impact of joint opening on tunnel deformation. Summary of the Invention

[0004] To more accurately assess the dynamic interaction between the tunnel and the soil and predict tunnel deformation under seismic loads, this invention proposes a new refined numerical modeling and calculation method for the seismic response of shield tunnels, which can be used to predict and evaluate the seismic resistance of tunnels.

[0005] This invention provides the following technical solution:

[0006] A method for simulating the dynamic interaction between a tunnel boring machine (TBM) and soil based on OpenSees includes the following steps:

[0007] S1: Set boundary conditions and establish a finite element model of tunnel-soil dynamic interaction;

[0008] S2: Define soil material properties and perform gravity analysis on the finite element model of tunnel-soil dynamic interaction;

[0009] S3: Under the premise that the initial stress state of the soil remains unchanged, the soil displacement is zeroed out;

[0010] S4: Add shield tunnel segments, bolts at joints, and pressure-resistant rubber lining material units and material information, and set the contact surface between the tunnel and the soil;

[0011] S5: Bind fiber-based nonlinear beam elements to the sides of the segment unit to simulate the nonlinear characteristics of the segment;

[0012] S6: Changes the soil properties from linear elastic to elastoplastic;

[0013] S7: Perform incremental dynamic analysis on the model, with seismic excitation applied at the bottom of the model.

[0014] Preferably, in step S1, a dangerous section soil area is selected, and a two-dimensional tunnel-soil dynamic interaction finite element model is established. The two-dimensional tunnel-soil dynamic interaction finite element model is established using the middle 1 / 3 width section of a single-layer lining ring structure, and numerical calculations are performed. The overall longitudinal width of the model is set to 1 / 3 of the lining ring width, where the maximum height h of the numerical model mesh size is... max The selection is determined by the following formula:

[0015]

[0016] Where v s f represents the shear wave velocity of the softest soil layer; max This represents the maximum frequency of the input ground motion.

[0017] Preferably, in step S1, the boundary conditions of the tunnel-soil dynamic interaction finite element model are set as follows:

[0018] (1) On both sides of the model, bind the displacement free ends at the nodes at the same height to ensure that the two opposite vertical sides of the model can move simultaneously under the action of external loads.

[0019] (2) At the bottom of the model, fix the vertical degrees of freedom of all nodes. Since the nodes at the same height on both sides of the model have been tied, the nodes on both sides of the bottom of the model are completely fixed. Apart from these two points, the horizontal direction at the bottom is not restricted. Use this direction to input the seismic excitation.

[0020] (3) Set impermeable boundaries at the bottom and sides of the model, set the initial pore pressure of all nodes of the soil at the ground surface and above the groundwater level to 0, and fix all pore pressure degrees of freedom.

[0021] (4) At the free field boundary of the model, a thicker free field soil column is set on each side of the model to simulate the free field boundary, with the thickness set to 700 to 800 times the thickness of the original model.

[0022] (5) Regarding the treatment of the free field soil column boundary at both ends of the model, the same as the treatment of the soil boundary of the original model is used. The displacement free ends of the nodes at the same height on both sides of the soil column (left and right) are bound to ensure that the nodes on both sides of the soil column can move together in the horizontal and vertical directions. The vertical degree of freedom of all nodes at the bottom of the soil column and the horizontal degree of freedom of the two outermost nodes at the bottom are fixed. Regarding the pore pressure treatment, the pore pressure degree of freedom of all soil nodes at the ground surface and above the groundwater level of the soil column is fixed, and the initial pore pressure is set to 0. Finally, the soil columns on both sides are connected to the original model, and the displacement free ends of the corresponding side nodes of the free field soil column at the same height and the soil of the original model are bound together so that they can move together.

[0023] Preferably, in step S2, for liquefiable saturated soil, the water-soil coupling element, namely the FourNodeQuadUP element, in OpenSees is used to simulate the saturated sand in this numerical model; for non-liquefiable soil types, the multi-yield surface plastic constitutive relation is used for simulation.

[0024] Preferably, in step S2, during the application of gravity load, the soil material behavior is linear elastic, and in the subsequent rapid dynamic loading phase, the soil stress-strain response is transformed into elastoplastic behavior through material renewal treatment.

[0025] Preferably, in step S4, the tunnel-soil contact surface is set as a thin-layer interface unit with a unit thickness of 0.1m, and the unit is located between the outer perimeter of the tunnel lining and the adjacent soil.

[0026] Preferably, in step S4, zero-length units are used to simulate the bolts and rubber pressure-resistant pads in the joint structure. The zero-length units that simulate the connection between the bolts and rubber pressure-resistant pads are to bind corresponding nodes that share the same coordinate position on the contact surfaces of two adjacent pipe segments, and the arrangement direction of the units is perpendicular to the contact surfaces of the pipe segments.

[0027] More preferably, the rubber compression liner and connecting bolts are simulated in the direction of the segment contact surface; the rubber compression liner uses a uniaxial elastic material, which can approximately simulate the friction and contact pressure between adjacent segments; the required parameter of the uniaxial elastic material, the tangent modulus E, is calculated by the following formula:

[0028]

[0029] Among them, E c The segment's elastic modulus is represented by I; the segment's moment of inertia is represented by L; the segment's ring width is represented by n; and the number of bolts is represented by G. b S represents the bolt shear modulus; bThe value represents the cross-sectional area of ​​the bolt; m represents the rectangular section modulus; l represents the length of the connecting bolt; the connecting bolt uses a uniaxial Giuffre-Menegotto-Pinto steel reinforcement model material with isotropic strain hardening, and the material type is Steel02 in OpenSees.

[0030] Compared with the prior art, the present invention has at least the following advantages:

[0031] 1. This invention uses the dynamic time-domain finite element method, which can conveniently simulate various complex geological conditions and structural forms; taking into account the soil liquefaction effect, it uses the same mesh element and different constitutive types to simulate liquefiable and non-liquefiable soil, which can reflect the real deformation between the soil and the tunnel, and greatly improves the applicability of this invention to various tunnel projects.

[0032] 2. This invention uses linear elastic soil material during gravity loading of the finite element model, and then updates it to elastoplastic soil material during the seismic dynamic loading stage, accurately simulating the stress-strain response of the tunnel structure under seismic action; and uses a composite element of nonlinear beam elements based on fiber cross-section and quadrilateral solid elements to simulate the nonlinear material properties and geometric characteristics of the tunnel segments.

[0033] 3. The present invention sets a thin-layer contact surface unit between the contact surface of the tunnel and the soil, which effectively simulates the interaction between the structure and the soil and greatly improves the accuracy of the model;

[0034] 4. This invention uses zero-length units to simulate the rubber pressure-resistant gaskets and bolts between pipe segments, thereby accurately simulating the rapid changes in contact stress and bolt connection force between adjacent pipe segments caused by the opening and misalignment of the joint structure. Attached Figure Description

[0035] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0036] Figure 1 This is a flowchart illustrating the shield tunnel-soil dynamic interaction simulation method based on OpenSees according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the numerical model of the dynamic interaction between the shield tunnel and the soil according to an embodiment of the present invention;

[0038] Figure 3 These are simplified cross-sectional views of the tunnel and schematic diagrams of the contact surface unit thickness in embodiments of the present invention;

[0039] Figure 4 This is a schematic diagram illustrating the use of zero-length units to simulate rubber gaskets and connecting bolts between tunnel segments in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram showing the position and binding method of the nonlinear beam element and the quadrilateral solid element in an embodiment of the present invention. Detailed Implementation

[0041] The following detailed description of a shield tunnel-soil dynamic interaction simulation method based on OpenSees, with reference to specific embodiments, is provided. These embodiments are for comparison and explanation purposes only, and the present invention is not limited to these embodiments.

[0042] Example 1

[0043] See Figure 1 The shield tunnel-soil dynamic interaction simulation method based on OpenSees provided in this embodiment predicts and evaluates the seismic resistance of the tunnel through refined numerical modeling and calculation of the tunnel's seismic response, including the following steps:

[0044] S1: Set boundary conditions and establish a finite element model of tunnel-soil dynamic interaction;

[0045] S2: Define soil material properties and perform gravity analysis on the finite element model of tunnel-soil dynamic interaction;

[0046] S3: Under the premise that the initial stress state of the soil remains unchanged, the soil displacement is zeroed out;

[0047] S4: Add shield tunnel segments, bolts at joints, and pressure-resistant rubber lining material units and material information, and set the contact surface between the tunnel and the soil;

[0048] S5: Bind fiber-based nonlinear beam elements to the sides of the segment unit to simulate the nonlinear characteristics of the segment;

[0049] S6: Changes the soil properties from linear elastic to elastoplastic;

[0050] S7: Perform incremental dynamic analysis on the model, with seismic excitation applied at the bottom of the model.

[0051] Preferably, in step S1, a dangerous section soil area is selected, and a two-dimensional tunnel-soil dynamic interaction finite element model is established. The two-dimensional tunnel-soil dynamic interaction finite element model is established using the middle 1 / 3 width section of a single-layer lining ring structure, and numerical calculations are performed. The overall longitudinal width of the model is set to 1 / 3 of the lining ring width, where the maximum height h of the numerical model mesh size is... max The selection is determined by the following formula:

[0052]

[0053] Where v s f represents the shear wave velocity of the softest soil layer; max This represents the maximum frequency of the input ground motion.

[0054] Preferably, in step S1, the boundary condition setting steps for the tunnel-soil dynamic interaction finite element model are as follows:

[0055] (1) On both sides of the model, bind the displacement free ends at the nodes at the same height to ensure that the two opposite vertical sides of the model can move simultaneously under the action of external loads.

[0056] (2) At the bottom of the model, fix the vertical degrees of freedom of all nodes. Since the nodes at the same height on both sides of the model have been tied, the nodes on both sides of the bottom of the model are completely fixed. Apart from these two points, the horizontal direction at the bottom is not restricted. Use this direction to input the seismic excitation.

[0057] (3) Set impermeable boundaries at the bottom and sides of the model, set the initial pore pressure of all nodes of the soil at the ground surface and above the groundwater level to 0, and fix all pore pressure degrees of freedom.

[0058] (4) At the free field boundary of the model, a thicker free field soil column is set on each side of the model to simulate the free field boundary, with the thickness set to 700 to 800 times the thickness of the original model.

[0059] (5) Regarding the treatment of the free field soil column boundary at both ends of the model, the same as the treatment of the soil boundary of the original model is used. The displacement free ends of the nodes at the same height on both sides of the soil column (left and right) are bound to ensure that the nodes on both sides of the soil column can move together in the horizontal and vertical directions. The vertical degree of freedom of all nodes at the bottom of the soil column and the horizontal degree of freedom of the two outermost nodes at the bottom are fixed. Regarding the pore pressure treatment, the pore pressure degree of freedom of all soil nodes at the ground surface and above the groundwater level of the soil column is fixed, and the initial pore pressure is set to 0. Finally, the soil columns on both sides are connected to the original model, and the displacement free ends of the corresponding side nodes of the free field soil column at the same height and the soil of the original model are bound together so that they can move together.

[0060] Preferably, in step S2, for liquefiable saturated soil, the water-soil coupling element, namely the FourNodeQuadUP element, in OpenSees is used to simulate the saturated sand in this numerical model; for non-liquefiable soil types, the multi-yield surface plastic constitutive relation is used for simulation.

[0061] Preferably, in step S2, during the application of gravity load, the soil material behavior is linear elastic, and in the subsequent rapid dynamic loading phase, the soil stress-strain response is transformed into elastoplastic behavior through material renewal treatment.

[0062] Preferably, in step S4, the tunnel-soil contact surface is set as a thin-layer interface unit with a unit thickness of 0.1m, and the unit is located between the outer perimeter of the tunnel lining and the adjacent soil.

[0063] Preferably, in step S4, zero-length units are used to simulate the bolts and rubber pressure-resistant pads in the joint structure. The zero-length units that simulate the connection between the bolts and rubber pressure-resistant pads are to bind corresponding nodes that share the same coordinate position on the contact surfaces of two adjacent pipe segments, and the arrangement direction of the units is perpendicular to the contact surfaces of the pipe segments.

[0064] In this embodiment, the connecting bolts are simulated using a uniaxial Giuffre-Menegotto-Pinto steel reinforcement model with isotropic strain hardening. The material type can be directly used from the Steel02 material in OpenSees.

[0065] More preferably, a uniaxial elastic material is provided in the direction of the contact surface of the tube segment to approximately simulate the frictional force between the two; the tangent modulus E required for the uniaxial elastic material model is calculated by the following formula:

[0066]

[0067] Among them, E c The segment's elastic modulus is represented by I; the segment's moment of inertia is represented by L; the segment's ring width is represented by n; and the number of bolts is represented by G. b S represents the bolt shear modulus; b represents the cross-sectional area of ​​the bolt; m represents the rectangular section modulus; l represents the length of the connecting bolt.

[0068] The material model used for the rubber compression liner and the method for calculating its tangential modulus are described. The material model takes into account the properties of the pipe segments and bolts, and simulates the frictional force in the direction of the pipe segment contact surface.

[0069] Example 2

[0070] The shield tunnel-soil dynamic interaction simulation method based on OpenSees provided in this embodiment includes the following steps:

[0071] S1: Set boundary conditions and establish a finite element model of tunnel-soil dynamic interaction;

[0072] A two-dimensional finite element model was established for the critical section soil area. Instead of using a full-width model of each tunnel lining ring, a finite element model was created for the middle 1 / 3 width of the single-layer lining ring structure, significantly improving computational efficiency. The overall model's longitudinal width was set to 1 / 3 of the lining ring width.

[0073] The selection of the numerical model mesh size is determined by the maximum height hmax of the model mesh, using the following formula:

[0074]

[0075] Where v s f represents the shear wave velocity of the softest soil layer; max This represents the maximum frequency of the input ground motion.

[0076] The specific steps for setting boundary conditions are as follows:

[0077] (1) On both sides of the model, the displacement free ends at the same height node are bound to ensure that the two opposite vertical sides of the model can move simultaneously under the action of external load. This is to effectively reflect the boundary effect of the layered shear deformation soil box and simulate the shear motion of the soil under the action of seismic load.

[0078] (2) At the bottom of the model, fix the vertical degrees of freedom of all nodes. Since the nodes at the same height on both sides of the model have been tied, the nodes on both sides of the bottom of the model are completely fixed. Apart from these two points, the horizontal direction at the bottom is not restricted. Use this direction to input the seismic excitation.

[0079] (3) Impermeable boundaries are set at the bottom and sides of the model, the initial pore pressure of all nodes of the soil at the ground surface and above the groundwater level is set to 0, and all pore pressure degrees of freedom are fixed to meet the actual engineering soil liquefaction conditions used in this model.

[0080] (4) At the free field boundary of the model, a thicker free field soil column is set on each side of the model to simulate the free field boundary based on the original model. The thickness is set to 700 to 800 times the thickness of the original model. In the method of this embodiment, the thickness is 500m and the width is set to 1m.

[0081] (5) Regarding the boundary treatment of the free-field soil columns at both ends of the model, the treatment is the same as that of the original model's soil boundary. The displacement free ends of the nodes at the same height on both sides of the soil columns (left and right) are bound to ensure that the nodes on both sides of the soil column can move together in both horizontal and vertical directions. The vertical degree of freedom of all nodes at the bottom of the soil column and the horizontal degree of freedom of the two outermost nodes at the bottom are fixed. Regarding pore pressure treatment, the pore pressure degree of freedom of all soil nodes at the ground surface and above the groundwater level of the soil column is fixed, and the initial pore pressure is set to 0. Finally, the soil columns on both sides are connected to the original model, such as... Figure 2As shown, the displacement free ends of the corresponding side nodes of the free field soil column and the original model soil at the same height are bound together (equalDOF) so that they move together.

[0082] S2: Define soil material properties and perform gravity analysis on the finite element model of tunnel-soil dynamic interaction;

[0083] For the liquefiable saturated soil in the model, the water-soil coupled element in OpenSees, specifically the FourNodeQuadUP element, is used to simulate the saturated sand in this numerical model. Each node of this element has three degrees of freedom: DOF1 and DOF2, which describe the displacement of the solid in the x and y directions, and DOF3, which describes the fluid pressure, i.e., the pore pressure. The PressureDependMultiYield material is applied to the aforementioned FourNodeQuadUP element, a solid-fluid fully coupled element with very low permeability, to simulate the seismic response of the soil under completely undrained conditions in this tunnel-soil dynamic interaction finite element model.

[0084] For the non-liquefiable soil type in the model, a multi-yield-surface plastic constitutive relation is used for simulation, with the yield surface type being Von Mises multi-yield surfaces, to reflect the elasto-plastic properties of the soil under shear hysteresis and the permanent deformation of the soil. This constitutive model uses the PressureIndependMultiYield material type and is applied to the FourNodeQuadUP element.

[0085] During the application of gravity loads, the soil material behaves linearly elastically. In the subsequent rapid dynamic loading phase, the soil stress-strain response is transformed into elastoplastic behavior through material renewal treatment.

[0086] S3: Under the premise that the initial stress state of the soil remains unchanged, the soil displacement is zeroed out;

[0087] S4: Add shield tunnel segments, bolts at joints, and pressure-resistant rubber lining material units and material information, and set the contact surface between the tunnel and the soil;

[0088] In the above embodiments of the present invention, a two-dimensional finite element model is established using a composite element of nonlinear beam elements based on fiber cross-sections and quadrilateral solid elements. The former is used to represent material properties and reflect the characteristics of reinforced concrete cross-sections, while the latter is used to reflect the geometry of the structure and provide a volumetric representation of the structure.

[0089] In the nonlinear beam element based on fiber cross section used in this invention, the Giuffre-Menegotto-Pinto model is used to simulate the tunnel segment reinforcement, and the material type used is Steel02 material in OpenSees.

[0090] This invention uses a uniaxial concrete material with tensile strength and linear tensile softening to simulate the core concrete and concrete cover of tunnel segments, namely the Concrete02 material in OpenSees.

[0091] In the quadrilateral solid element of this invention, the elastic-fully plastic Drucker-Prager model is used to simulate the lining concrete. The stiffness in the composite element is mainly provided by the fiber-based nonlinear beam element; therefore, the stiffness of the quadrilateral solid element is weakened. The stiffness of the fiber-based nonlinear beam element is set to be the same as that of the elastic cantilever beam, and the modulus of the quadrilateral element is set to 0.0001 times the actual modulus of the elastic cantilever beam.

[0092] This invention incorporates thin-layer interface units at the junction of the tunnel structure and the soil to account for stiffness variations within the structure-soil unit. Given the significant stiffness difference between the reinforced concrete tunnel lining segments and the adjacent soil, a thin-layer interface unit with a thickness of 0.1 m is used at the tunnel lining perimeter between the tunnel and the adjacent soil. A schematic diagram of this thin-layer interface unit is shown below. Figure 3 As shown:

[0093] This invention considers the stiffness difference between the structure and the soil, and applies shear parameter weakening to the thin-layer interface elements between the two. Given that the shield tunnel is distributed across different soil layers, segmented thin-layer interface elements with weakened shear parameters are used to simulate the tunnel-soil contact surface. A shear parameter weakening coefficient of 0.7 is used.

[0094] This invention uses zero-length elements to simulate the bolts and rubber compression pads in the joint structure. A schematic diagram of the joint structure is shown below. Figure 4 As shown.

[0095] The zero-length element of this invention has a unit length of zero and can bind two nodes located at the same position. The zero-length element simulating the connection bolt and the rubber compression liner binds corresponding nodes on the contact surfaces of two adjacent pipe segments that share the same coordinate position, and the element arrangement direction is perpendicular to the pipe segment contact surface. The material of the connection bolt is simulated using a uniaxial Giuffre-Menegotto-Pinto steel reinforcement model with isotropic strain hardening, specifically Steel02 material from OpenSees. The material of the rubber compression liner is simulated using a uniaxial elastic compressive and tensile material.

[0096] To fully simulate the seismic response of a joint structure under seismic loads, this invention considers the friction between the bolts and the tunnel segment contact surfaces. A uniaxial elastic material is placed along the contact surface direction to approximate the frictional force between them. The tangent modulus E required for this uniaxial elastic material model can be calculated as follows:

[0097]

[0098] Among them, E c The segment's elastic modulus is represented by I; the segment's moment of inertia is represented by L; the segment's ring width is represented by n; and the number of bolts is represented by G. b S represents the bolt shear modulus; b represents the cross-sectional area of ​​the bolt; m represents the rectangular section modulus; l represents the length of the connecting bolt.

[0099] S5: As Figure 5 As shown, nonlinear beam elements based on fiber sections are bound to the sides of the segment unit to simulate the nonlinear characteristics of the segment.

[0100] S6: Changes the soil properties from linear elastic to elastoplastic;

[0101] S7: Perform incremental dynamic analysis on the model. The initial state uses the above-mentioned initial stress field of the soil, and the seismic excitation is applied to the bottom of the model.

[0102] Through the above steps, this invention can establish a refined numerical modeling and calculation method for the seismic response of shield tunnels. In the future, this method can be used to perform vulnerability analysis of target tunnels, draw tunnel loss probability curves and functional recovery probability curves, predict the seismic resistance of tunnels, and become the basis for building a framework for assessing the seismic toughness of tunnels.

[0103] The method provided in the above embodiments of the present invention focuses on replacing the full-width model of each ring of tunnel lining with a single-layer lining replacement structure model of the middle 1 / 3 width for calculation, which greatly improves the calculation efficiency. Taking into account the soil liquefaction effect, the nonlinear characteristics of the tunnel segments and the joint structure at the connection of adjacent tunnel segments, it can accurately simulate the liquefaction characteristics of saturated sand under seismic loads, the nonlinear characteristics of steel bars and concrete in the tunnel segments, and the deformation and misalignment of the tunnel segment joints.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An OpenSees-based simulation method of shield tunnel-soil dynamic interaction, characterized in that, The method comprises the following steps: S1: setting boundary conditions, and establishing a tunnel-soil dynamic interaction finite element model; S2: defining soil material properties, and performing gravity analysis on the tunnel-soil dynamic interaction finite element model; S3: clearing the displacement of the soil under the premise that the initial stress state of the soil remains unchanged; S4: adding shield tunnel segments, bolt and compression rubber gasket material units and material information at the joint, and setting a contact surface between the tunnel and the soil; S5: binding a nonlinear beam element based on a fiber section on the side of the segment element to simulate the nonlinear characteristics of the segment; S6: converting the soil properties from linear elasticity to elastoplasticity; S7: performing incremental dynamic analysis on the model, and applying the initial state of the soil initial stress field and the seismic excitation at the bottom of the model. In the step S1, the dangerous section of soil is selected, a two-dimensional tunnel-soil dynamic interaction finite element model is established, a two-dimensional tunnel-soil dynamic interaction finite element model is established by using a single-layer lining ring structure of the middle 1 / 3 width section and numerical calculation is carried out, the longitudinal width of the overall model is set to 1 / 3 of the width of the lining ring, wherein the maximum height h of the numerical model grid size is 1 / 3 of the height of the lining ring max is determined by selecting the following formula: where v s represents the shear wave velocity of the softest soil layer; f max represents the maximum frequency in the input ground motion.

2. The OpenSees-based shield tunnel-soil dynamic interaction simulation method according to claim 1, wherein, In the step S1, the boundary condition setting of the tunnel-soil dynamic interaction finite element model comprises the following steps: (1) on both sides of the model, the displacement free ends of the nodes at the same height are bound to ensure that the two vertical sides on both sides of the model can move simultaneously under the action of external load; (2) at the bottom of the model, the vertical degrees of freedom of all nodes are fixed, since the nodes at the same height on both sides of the model have been bound, the nodes on both sides of the bottom of the model are completely fixed, except for the two points, the bottom is not restricted in the horizontal direction, and the seismic excitation is input in the direction; (3) the impermeable boundary is set at the bottom and side of the model, the initial pore pressure of all nodes of the soil above the water level is 0, and all pore pressure degrees of freedom are fixed; (4) at the free field boundary of the model, a thicker free field soil column is arranged on both sides of the original model to simulate the free field boundary, and the thickness is 700-800 times the thickness of the original model; (5) in terms of the boundary treatment of the soil column at both ends of the model, the displacement free ends of the nodes at the same height on both sides of the soil column are bound to ensure that the nodes on both sides of the soil column can move in the horizontal and vertical directions, and the vertical degrees of freedom of all nodes at the bottom of the soil column and the horizontal degrees of freedom of the outermost two nodes at the bottom are fixed; in terms of the pore pressure treatment, the pore pressure degrees of freedom of all soil nodes above the water level at the ground surface of the soil column are fixed, and the initial pore pressure is 0; finally, the soil columns on both sides are connected with the original model, the displacement free ends of the corresponding side nodes of the free field soil column and the soil body of the original model at the same height are bound to move together. 3.The OpenSees-based shield tunnel-soil dynamic interaction simulation method according to claim 1, wherein, In the step S2, for the liquefiable saturated soil, the water-soil coupling element FourNodeQuadUP element in OpenSees is used to simulate the saturated sand in the numerical model; for the non-liquefiable soil type, a multi-yield surface plastic constitutive relation is used for simulation.

4. The OpenSees-based shield tunnel-soil dynamic interaction simulation method of claim 1, wherein, In the step S2, during the application of the gravity load, the soil material behaves in a linear elastic manner, and in the subsequent rapid dynamic loading stage, the stress-strain response of the soil is converted to elastoplasticity through material updating.

5. The OpenSees-based shield tunnel-soil dynamic interaction simulation method of claim 1, wherein, In the step S4, the tunnel-soil contact surface is set as a thin layer interface element, the element thickness is set as 0.1 m, and the element position is between the tunnel lining periphery and the adjacent soil.

6. The OpenSees-based shield tunnel-soil dynamic interaction simulation method of claim 1, wherein, In the step S4, the bolt and the rubber compression gasket in the joint structure are simulated by using zero-length elements, the zero-length elements for simulating the bolt and the rubber compression gasket are two adjacent pipe contact surfaces which share the same coordinate position and are bound together, and the element arrangement direction is perpendicular to the pipe contact surface.

7. The OpenSees-based shield tunnel-soil dynamic interaction simulation method of claim 6, wherein, The rubber compression gasket and the connecting bolt are simulated in the direction of the pipe contact surface; the rubber compression gasket uses a uniaxial elastic material which can approximately simulate the friction and contact pressure between adjacent pipes; the tangent modulus E required by the uniaxial elastic material model is calculated by the following formula: where E c represents the segment elastic modulus; I represents the segment cross-sectional moment of inertia; L represents the segment ring width; n represents the number of bolts; G b represents the bolt shear modulus; S b represents the bolt cross-sectional area; m represents the rectangular cross-sectional coefficient; and l represents the connecting bolt length. The connecting bolt uses a uniaxial Giuffre-Menegotto-Pinto steel reinforcement model material with isotropic strain hardening, and the material type is Steel02 in OpenSees.

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