Numerical simulation method for immersed tube tunnel joint based on nanofluid damping

Abstract

A numerical simulation method for vibration reduction of immersed tunnel joints based on nanofluids is disclosed, belonging to the field of immersed tunnel vibration reduction technology. The method includes the following steps: determining the connection method of existing joints; establishing a simplified mechanical model of the joint; defining the simulation method of each component in the simplified mechanical model; introducing nanofluid energy-absorbing materials as vibration reduction measures for the joint; arranging the nanofluid vibration reduction measures; defining the input load; and comparing the energy dissipation characteristics of the nodes. This invention proposes a three-dimensional numerical simulation method for joints based on a simplified mechanical model of immersed tunnel joints to realistically reproduce their mechanical response characteristics. Furthermore, by introducing nanofluid energy-absorbing materials at the joint as vibration reduction measures, it overcomes the shortcomings of traditional joint vibration reduction measures, such as large volume, inability to recover after deformation, and low energy absorption density. Evaluation of the improved joint's energy dissipation characteristics shows a significant improvement in its vibration reduction performance.

Description

Technical Field

[0001] This invention belongs to the field of submerged tunnel vibration reduction technology, specifically relating to a numerical simulation method for vibration reduction of submerged tunnel joints based on nanofluids. Background Technology

[0002] Immersed tunnels are an important transportation link connecting coastal urban clusters, with significant social and economic benefits. They also have advantages such as not affecting waterway navigation, improving comfort, increasing concealment, and being unaffected by weather, and have been widely used in recent years.

[0003] Immersed tunnels are constructed by first using prefabricated pipe sections, then floating these sections to a designated location, safely placing them on a pre-prepared foundation, and finally using hydraulic pressure welding technology to weld the sections together. With the assistance of other construction conditions, a connected pipeline is formed, linking the tunnel to other areas such as land, creating a connecting channel that meets the needs of both land and water transportation.

[0004] Due to their importance and the unique nature of being underwater, the damage to immersed tunnels can have catastrophic consequences and is difficult to repair. Therefore, for immersed tunnels, it is essential to employ appropriate vibration reduction and control methods and measures to minimize and avoid earthquake damage, based on a safe and reasonable structural design.

[0005] The joints of immersed tunnel sections are the weakest points in the overall structure and a critical aspect of immersed tunnel structural design. To mitigate damage to these joints during earthquakes and improve their seismic performance, damping measures at the joints have become one of the most important methods. Currently, damping devices at the joints are mainly concentrated inside the sections and are large in size. Existing damping measures use traditional energy-absorbing materials, which have low energy density and cannot recover their deformation after absorbing energy, meaning they cannot be reused. Summary of the Invention

[0006] This invention discloses a numerical simulation method for vibration reduction based on nanofluids in immersed tunnel joints. Based on existing connection methods for immersed tunnel joints, this invention establishes a simplified mechanical model of the joint and proposes a three-dimensional numerical simulation method to realistically reproduce its mechanical response characteristics. Furthermore, nanofluid energy-absorbing materials are introduced at the joint as a vibration reduction measure, overcoming the shortcomings of traditional joint vibration reduction measures such as large volume, inability to recover after deformation, and low energy absorption density. Evaluation of the improved joint's energy dissipation characteristics reveals a significant improvement in its vibration reduction performance.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A numerical simulation method for immersed tunnel segment joints based on nanofluid damping includes the following steps:

[0009] Step 1: Determine the connection method for existing pipe joints;

[0010] Step 2: Establish a simplified mechanical model of the pipe joint;

[0011] Step 3: Define the simulation method for each component in the simplified mechanical model;

[0012] Step 4: Introduce nanofluid energy-absorbing materials as a vibration damping measure for pipe joints;

[0013] Step 5: Arrangement of nanofluid vibration reduction measures;

[0014] Step 6: Enter the definition of the load;

[0015] Step 7: Comparison of node energy consumption characteristics.

[0016] Preferably, step 1 includes: the existing pipe joint connection methods include shear keys, OMEGA waterstops and GINA waterstops, the shear keys include horizontal shear keys and vertical shear keys, and the OMEGA waterstops are ignored in the numerical simulation.

[0017] Preferably, step 2 includes: in the simplified mechanical model of the pipe joint, the axial deformation of the pipe joint is damped by the compression of the GINA waterstop, the axial compression response of the GINA waterstop is simulated by a variable stiffness spring element in the x-axis direction, and its axial stiffness is determined by K... x Definition: The tangential deformation of the pipe joint is achieved through shear keys in the y-axis and z-axis directions. The response of the shear keys is simulated by variable stiffness spring elements in the y-axis and z-axis directions, respectively. Their stiffness in the y-axis and z-axis directions is determined by K... y and K z The torsional deformation of the pipe joint is defined by the torsion of the GINA waterstop. The torsional response of the GINA waterstop is simulated by a constant stiffness torsion spring element. Considering that when torsion occurs, half of the GINA waterstop is under compression and half is under tension, the constant stiffness of the torsion along the y-axis and z-axis needs to be considered separately. Therefore, the constant stiffness torsion spring element includes a horizontal torsion spring and a vertical torsion spring. The torsional stiffness of the horizontal torsion spring and the vertical torsion spring are respectively defined by K. t1 and K t2 definition.

[0018] Preferably, in step 3, the axial response of the GINA waterstop is defined using a nonlinear elastic uniaxial material in the OpenSees program to achieve stiffness changes under different axial forces; the shear response of the shear key is defined using an ideal elastic-plastic uniaxial material with gaps and an ideal elastic-plastic uniaxial material in the OpenSees program, and the parallel connection is achieved using the parallel uniaxial material function in OpenSees; the torsional response of the GINA waterstop around the transverse and vertical directions is defined using an elastic uniaxial material in the OpenSees program.

[0019] Preferably, step 4 includes: fitting the stress-strain relationship of the nanofluid energy-absorbing material with a high-damping rubber uniaxial material in the OpenSees program, introducing the nanofluid energy-absorbing material as a vibration damping measure for the pipe joint, wherein the nanofluid energy-absorbing material constitutes the damping fluid in the nanofluid damper.

[0020] Preferably, in step 5, considering that the immersed tunnel is in direct contact with soil and water in actual engineering, the installation and subsequent replacement of energy-consuming devices are difficult. Therefore, the nanofluid damper is installed inside the immersed tunnel. The nanofluid damper includes an x-axis nanofluid damper, a y-axis nanofluid damper and a z-axis nanofluid damper connecting the tunnel sections. The y-axis nanofluid damper and the z-axis nanofluid damper are respectively arranged in the two deformation directions of the shear key.

[0021] Preferably, step 6 includes: in order to examine the energy dissipation characteristics of the immersed tunnel joint after adding the nanofluid damper, applying a cyclic displacement load to the established simplified mechanical model of the joint.

[0022] Preferably, step 7 includes: obtaining the load-displacement curves of the pipe joint node in different directions under cyclic displacement load, and examining the change in the energy dissipation characteristics of the pipe joint node after setting the nanofluid damper.

[0023] Preferably, step 3 includes the following specific contents:

[0024] (1) When the compression deformation of GINA waterstop is simulated using a nonlinear elastic uniaxial material, the specific definition is as follows:

[0025] uniaxialMaterial ElasticMultiLinear$GINA_x_Tag-strain$strainPoints-stress$stressPoints;

[0026] (2) The shear response of the shear key is simulated using an ideal elastoplastic uniaxial material with a gap, an ideal elastoplastic uniaxial material, and a parallel uniaxial material, as specifically defined below:

[0027] uniaxialMaterial ElasticPPGap$Tag1$E1$Fy1$gap1;

[0028] uniaxialMaterial ElasticPPGap$Tag2$E2$Fy2$gap2;

[0029] uniaxialMaterial ElasticPP$Tag3$E3$epsyP;

[0030] uniaxialMaterial Parallel$Tag4$Tag1$Tag2;

[0031] uniaxialMaterial Parallel$Tag5$Tag3$Tag4;

[0032] (3) The torsional response of GINA waterstop in the transverse and vertical directions is simulated using an elastic uniaxial material, as specifically defined below:

[0033] uniaxialMaterial Elastic$Tag$E.

[0034] Preferably, step 4 includes the following:

[0035] The energy dissipation of nanofluid materials is simulated using a high-damping uniaxial rubber material. The specific definition of the simulated nanofluid material is as follows:

[0036] uniaxialMaterial KikuchiAikenHDR$Tag$tp$ar$hr.

[0037] An application of a numerical simulation method based on nanofluid damping for immersed tunnel joints is presented. This method is applied to the damping of immersed tunnel joints by installing nanofluid dampers along the x-axis, y-axis, and z-axis between the pipe wall mating ends of adjacent joints to improve the seismic resistance of the joints.

[0038] The beneficial effects of the numerical simulation method for immersed tunnel joint based on nanofluid vibration reduction of the present invention are as follows:

[0039] This invention establishes a simplified mechanical model of the immersed tunnel segment joint based on existing connection methods, and proposes a three-dimensional numerical simulation method for the joint to realistically reproduce its mechanical response characteristics. Furthermore, a nanofluid energy-absorbing material is introduced at the joint as a vibration damping measure, overcoming the shortcomings of traditional joint vibration damping measures such as large volume, inability to recover after deformation, and low energy absorption density. Evaluation of the improved joint's energy dissipation characteristics reveals a significant improvement in its vibration damping performance.

[0040] Instruction manual illustrations

[0041] To more clearly express and illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0042] Figure 1 The existing flexible joint structure of immersed tunnel segments (the figure shows a partial structure at the joint of two segments).

[0043] Figure 2 , three Simplified mechanical model of vascular joint.

[0044] Figure 3 Simulation method of shear key.

[0045] Figure 4 Arrangement of the x-axis damping device (nanofluid damper).

[0046] Figure 5 Arrangement of the vibration damping device (nanofluid damper) in the z-axis direction.

[0047] Figure 6 Displacement loading mode.

[0048] Figure 7 Relationship between shear force and displacement of concrete shear key in the y-axis direction (left: no damping device installed; right: damping device installed).

[0049] Figure 8 Relationship between shear force and displacement of steel shear key in the z-axis direction (left: no damping device; right: with damping device).

[0050] Figure 9 Cross-sectional view of GINA waterstop (unit: mm).

[0051] Figure 10 Force-displacement curves of GINA waterstop.

[0052] Figure 11 The force-displacement relationship in the x-direction after setting up the damping device (nanofluid damper).

[0053] 1. Cross-section of the outer wall of the first tunnel section; 2. Cross-section of the outer wall of the second tunnel section; 3. GINA waterstop; 4. Steel end shell; 5. OMEGA waterstop; 6. Steel shear key; 7. Variable stiffness spring element in the y-axis direction; 8. Variable stiffness spring element in the z-axis direction; 9. Immersed tunnel section one (schematic); 10. Immersed tunnel section two (schematic); 11. Vertical torsion spring; 12. Horizontal torsion spring; 13. Variable stiffness spring element in the x-axis direction; 14. Nanofluid damper in the x-axis direction; 15. Nanofluid damper in the z-axis direction. Detailed Implementation

[0054] The following description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0055] Example 1

[0056] A numerical simulation method for immersed tunnel segment joints based on nanofluid damping includes the following steps:

[0057] Step 1: Determine the connection method for existing pipe joints;

[0058] Step 2: Establish a simplified mechanical model of the pipe joint;

[0059] Step 3: Define the simulation method for each component in the simplified mechanical model;

[0060] Step 4: Introduce nanofluid energy-absorbing materials as a vibration damping measure for pipe joints;

[0061] Step 5: Arrangement of nanofluid vibration reduction measures;

[0062] Step 6: Enter the definition of the load;

[0063] Step 7: Comparison of node energy consumption characteristics.

[0064] Example 2

[0065] Based on Example 1, this example discloses:

[0066] Step 1 includes: existing pipe joint connection methods, such as... Figure 1 As shown, it includes shear keys (including steel shear keys and concrete shear keys), OMEGA waterstops, and GINA waterstops. OMEGA waterstops, as a second layer of waterproofing, are slightly less effective than GINA waterstops. Therefore, this invention only considers GINA waterstops and does not consider OMEGA waterstops, nor in numerical simulations.

[0067] Example 3

[0068] Based on Example 2, this example discloses:

[0069] Step 2 includes: establishing, for example, for pipe joints... Figure 2 The simplified mechanical model of the three-dimensional pipe joint shown is as follows: In the simplified mechanical model of the pipe joint, the axial deformation of the pipe joint is damped by the compression of the GINA waterstop. The axial compression response of the GINA waterstop is simulated by the variable stiffness spring element 13 in the x-axis direction, and its axial stiffness is determined by K. x Definition: The tangential deformation of the pipe joint is achieved through shear keys in the y-axis and z-axis directions. The response of the shear keys is simulated by variable stiffness spring elements 7 in the y-axis direction and 8 in the z-axis direction. Their stiffness in the y-axis and z-axis directions is respectively determined by K. y and K z The torsional deformation of the pipe joint is defined by the torsion of the GINA waterstop. The torsional response of the GINA waterstop is simulated by a constant stiffness torsion spring element, which includes a horizontal torsion spring 12 and a vertical torsion spring 11. The torsional stiffness of the horizontal torsion spring 12 and the vertical torsion spring 11 are respectively defined by K. t1 and K t2 Definition: Considering that when torsion occurs, half of the GINA waterstop is under compression and half is under tension, the torsional constant stiffness along the y-axis and z-axis needs to be considered separately. Therefore, a horizontal torsion spring 12 and a vertical torsion spring 11 are used to simulate torsion around the transverse and vertical axes, respectively.

[0070] In step 3, the axial response of the GINA waterstop is defined using a nonlinear elastic uniaxial material in the OpenSees program to achieve stiffness changes under different axial forces; the shear response of the shear key is defined using an ideal elastic-plastic uniaxial material with gaps and an ideal elastic-plastic uniaxial material in the OpenSees program, while utilizing the parallel connection function of parallel uniaxial materials in OpenSees to achieve... Figure 3 The connection method is shown; the torsional response of the GINA waterstop around the transverse and vertical axes is defined by the elastic uniaxial material in the OpenSees program.

[0071] Example 4

[0072] Based on Example 3, this example discloses:

[0073] Step 4 includes: fitting the stress-strain relationship of the nanofluid energy-absorbing material with a high-damping rubber uniaxial material in the OpenSees program, introducing the nanofluid energy-absorbing material as a vibration reduction measure for the pipe joint, wherein the nanofluid energy-absorbing material constitutes the damping fluid in the nanofluid damper.

[0074] Example 5

[0075] Based on Example 4, this example discloses:

[0076] In step 5, considering that the immersed tunnel is in direct contact with soil and water in actual engineering, the installation and subsequent replacement of energy-consuming devices are quite difficult. Therefore, nanofluid dampers are installed inside the immersed tunnel. These nanofluid dampers include an x-axis nanofluid damper 14, a y-axis nanofluid damper, and a z-axis nanofluid damper 15 connecting the tunnel sections. Figure 4 and 5 As shown, the nanofluid damper 15 along the y-axis and the nanofluid damper 15 along the z-axis are respectively arranged in the two deformation directions of the shear key.

[0077] Example 6

[0078] Based on Example 5, this example discloses:

[0079] Step 6 includes: In order to examine the energy dissipation characteristics of the immersed tunnel joint after adding a nanofluid damper, a cyclic displacement load is applied to the established simplified mechanical model of the joint.

[0080] Step 7 includes: obtaining the load-displacement curves of the pipe joint node in different directions under cyclic displacement load, and examining the change in the energy dissipation characteristics of the pipe joint node after setting the nanofluid damper.

[0081] Example 7

[0082] Based on Example 6, this example discloses:

[0083] Step 3 includes the following specific contents:

[0084] (1) When the compression deformation of GINA waterstop is simulated using a nonlinear elastic uniaxial material, the specific definition is as follows:

[0085] uniaxialMaterial ElasticMultiLinear$GINA_x_Tag-strain$strainPoints-stress$stressPoints;

[0086] The nonlinear stress-strain relationship of a nonlinear elastic uniaxial material is given by a series of straight lines defined by multiple points. The stress-strain relationship is nonlinear and elastic. This indicates that the uniaxial material follows the same curve during loading and unloading, without energy dissipation. The number of strain values ​​given is the same as the number of stress values.

[0087] (2) The shear response of the shear key is simulated using an ideal elastoplastic uniaxial material with a gap, an ideal elastoplastic uniaxial material, and a parallel uniaxial material, as specifically defined below:

[0088] uniaxialMaterial ElasticPPGap$Tag1$E1$Fy1$gap1;

[0089] Tag1 is an ideal elastoplastic uniaxial material with a gap. Its initial spacing of strain values ​​(or displacement values) is gap1, its slope is E1, and the stress (or force) when the material reaches the plastic state is Fy1.

[0090] uniaxialMaterial ElasticPPGap$Tag2$E2$Fy2$gap2;

[0091] Tag2 is an ideal elastoplastic uniaxial material with a gap. Its strain (or displacement) values ​​have an initial spacing of gap2, a slope of E2, and a stress (or force) of Fy2 when the material reaches the plastic state.

[0092] uniaxialMaterial ElasticPP$Tag3$E3$epsyP;

[0093] The elastoplastic uniaxial material Tag3 has a slope of E3 and the strain (or deformation) at which the material reaches the plastic state under tension is epsyP.

[0094] uniaxialMaterial Parallel$Tag4$Tag1$Tag2;

[0095] Material Tag1 and material Tag2 are connected in parallel to obtain a new material Tag4.

[0096] uniaxialMaterial Parallel$Tag5$Tag3$Tag4;

[0097] Material Tag3 and material Tag4 are connected in parallel to obtain a new material Tag5.

[0098] (3) The torsional response of GINA waterstop in the transverse and vertical directions is simulated using an elastic uniaxial material, as specifically defined below:

[0099] uniaxialMaterial Elastic$Tag$E.

[0100] The label for elastic uniaxial materials is Tag, with a slope of E.

[0101] Example 8

[0102] Based on Example 7, this example discloses:

[0103] Step 4 includes the following:

[0104] The energy dissipation of nanofluid materials is based on the friction at the solid-liquid interface within the nanopores, a mechanism that cannot yet be simulated mechanistically. Simulation can only be achieved macroscopically from the perspective of energy dissipation by matching the stress-strain relationship of the nanofluid material. Here, a high-damping uniaxial rubber material is used to simulate the nanofluid material, specifically defined as follows:

[0105] uniaxialMaterial KikuchiAikenHDR$Tag$tp$ar$hr.

[0106] The high-damping rubber uniaxial material is designated by Tag, rubber type as tp, rubber area as ar, and rubber height as hr.

[0107] Example 9

[0108] Based on Example 8, this example discloses:

[0109] A numerical simulation method for immersed tunnel segment joints based on nanofluid damping includes the following steps:

[0110] (1) Establish a three-dimensional six-degree-of-freedom two-node model. The two nodes share the same geometric position. One node is fixed with all degrees of freedom. This is achieved using the Fix command in OpenSees.

[0111] (2) The degrees of freedom of the two nodes are connected through the zeroLength element in OpenSees;

[0112] (3) The material definition in the zeroLength element is achieved through the material definition in step 3;

[0113] (4) By applying corresponding displacement loads in the x, y, and z directions (see...) Figure 6 The energy dissipation characteristics of nodes before and after the installation of the nanofluid damping device were evaluated.

[0114] (5) Figure 7 To establish the shear force versus displacement curves of the concrete shear key in the y-direction before and after the installation of the nanofluid damping device, it can be seen that when the maximum displacement applied before and after the installation of the nanofluid damping device (nanofluid damper) is the same, the maximum shear force borne by the joint with the damping device is 8.3 × 10⁻⁶. 5 kN, which is about 3 times higher than that without a damping device. According to the size of the hysteresis loop area of ​​the force-displacement curve of the pipe joint, the energy dissipation area of ​​the joint with a damping device is about 2 times higher than that without a damping device, and the energy dissipation effect is very significant.

[0115] (6) Figure 8 The shear force versus displacement curves of the steel shear key in the z-direction before and after the installation of the nanofluid damping device were established. It can be seen that when the maximum displacement applied before and after the installation of the nanofluid damping device is the same, the maximum shear force borne by the joint with the damping device is 1.7 × 10⁻⁶. 6 kN, which is about 59.7% higher than that without a damping device. According to the size of the hysteresis loop area of ​​the force-displacement curve of the pipe joint, the energy dissipation area of ​​the joint with a damping device is about 53.8% higher than that without a damping device, and the energy dissipation effect is also quite obvious.

[0116] (7) For typical GINA waterstops (see...) Figure 9 From this, the force-displacement curve of the GINA waterstop can be obtained. Figure 10 It can be seen that, due to the geometric shape of the GINA waterstop, the resistance to deformation is weak when the GINA ribs are initially subjected to force, but gradually increases as the compression deformation of the GINA increases. If the same nanofluid damping device as the horizontal and vertical shear key parts is used, the compressive stiffness of the GINA waterstop is much smaller than that of the nanofluid damping device. Therefore, after installing the nanofluid damping device axially, the axial force is much greater when compressed to the same displacement as without the damping device. Figure 11 As shown, the nodal stiffness of the device with nanofluid damping is significantly improved. Furthermore, since it is assumed that the GINA waterstop cannot dissipate energy, a hysteresis loop can be observed in the force-displacement curve after the addition of the nanofluid damping device, indicating that the energy dissipation performance and load-bearing capacity in the axial direction are significantly improved.

[0117] Example 10

[0118] Based on the above embodiments, this embodiment discloses:

[0119] An application of a numerical simulation method based on nanofluid damping for immersed tunnel joints is presented. This method is applied to the damping of immersed tunnel joints by installing nanofluid dampers along the x-axis, y-axis, and z-axis between the pipe wall mating ends of adjacent joints to improve the seismic resistance of the joints.

Claims

1. A numerical simulation method for immersed tunnel segment joints based on nanofluid vibration reduction, characterized in that, Includes the following steps: Step 1: Determine the connection method for existing pipe joints; Step 2: Establish a simplified mechanical model of the pipe joint; Step 3: Define the simulation method for each component in the simplified mechanical model; Step 4: Introduce nanofluid energy-absorbing materials as a vibration damping measure for pipe joints; Step 5: Arrangement of nanofluid vibration reduction measures; Step 6: Enter the definition of the load; Step 7: Comparison of node energy consumption characteristics; Step 1 includes: the existing pipe joint connection methods include shear keys, OMEGA waterstops and GINA waterstops, the shear keys include horizontal shear keys and vertical shear keys, and OMEGA waterstops are ignored in numerical simulation; Step 2 includes: In the simplified mechanical model of the pipe joint, the axial deformation of the pipe joint is damped by the compression of the GINA waterstop. The axial compression response of the GINA waterstop is simulated by a variable stiffness spring element in the x-axis direction, and its axial stiffness is determined by K. x Definition: The tangential deformation of the pipe joint is achieved through shear keys in the y-axis and z-axis directions. The response of the shear keys is simulated by variable stiffness spring elements in the y-axis and z-axis directions, respectively. Their stiffness in the y-axis and z-axis directions is determined by K... y and K z The torsional deformation of the pipe joint is defined by the torsion of the GINA waterstop. The torsional response of the GINA waterstop is simulated by a constant stiffness torsion spring element. Considering that when torsion occurs, half of the GINA waterstop is under compression and half is under tension, the constant stiffness of the torsion along the y-axis and z-axis needs to be considered separately. Therefore, the constant stiffness torsion spring element includes a horizontal torsion spring and a vertical torsion spring. The torsional stiffness of the horizontal torsion spring and the vertical torsion spring are respectively defined by K. t1 and K t2 definition; In step 3, the axial response of the GINA waterstop is defined using nonlinear elastic uniaxial materials in the OpenSees program to achieve stiffness changes under different axial forces; the shear response of the shear key is defined using ideal elastic-plastic uniaxial materials with gaps and ideal elastic-plastic uniaxial materials in the OpenSees program, and the parallel connection is achieved using the parallel connection function of parallel uniaxial materials in OpenSees; the torsional response of the GINA waterstop around the transverse and vertical directions is defined using elastic uniaxial materials in the OpenSees program. Step 4 includes: fitting the stress-strain relationship of the nanofluid energy-absorbing material with a high-damping rubber uniaxial material in the OpenSees program, introducing the nanofluid energy-absorbing material as a vibration reduction measure for the pipe joint, wherein the nanofluid energy-absorbing material constitutes the damping fluid in the nanofluid damper; In step 5, considering that the immersed tunnel is in direct contact with soil and water in actual engineering, the installation and replacement of energy-consuming devices are difficult. Therefore, the nanofluid damper is installed inside the immersed tunnel. The nanofluid damper includes an x-axis nanofluid damper, a y-axis nanofluid damper and a z-axis nanofluid damper connecting the tunnel sections. The y-axis nanofluid damper and the z-axis nanofluid damper are respectively arranged in the two deformation directions of the shear key. Step 6 includes: In order to examine the energy dissipation characteristics of the immersed tunnel joint after adding the nanofluid damper, a cyclic displacement load is applied to the established simplified mechanical model of the joint. Step 7 includes: obtaining the load-displacement curves of the pipe joint node in different directions under cyclic displacement load, and examining the change in the energy dissipation characteristics of the pipe joint node after setting the nanofluid damper.

2. The numerical simulation method for immersed tunnel joint based on nanofluid vibration reduction as described in claim 1, characterized in that, Step 3 includes the following specific contents: (1) When the compression deformation of GINA waterstop is simulated using a nonlinear elastic uniaxial material, the specific definition is as follows: uniaxialMaterial ElasticMultiLinear $GINA_x_Tag -strain $strainPoints -stress $stressPoints; (2) The shear response of the shear key is simulated using an ideal elastoplastic uniaxial material with a gap, an ideal elastoplastic uniaxial material, and a parallel uniaxial material, as specifically defined below: uniaxialMaterial ElasticPPGap $Tag1 $E1 $Fy1 $gap1; Tag1 is an ideal elastoplastic uniaxial material with a gap. Its initial spacing between strain or displacement values ​​is gap1, its slope is E1, and the stress or force when the material reaches the plastic state is Fy1. uniaxialMaterial ElasticPPGap $Tag2 $E2 $Fy2 $gap2; Tag2 is an ideal elastoplastic uniaxial material with a gap. Its initial spacing between strain or displacement values ​​is gap2, its slope is E2, and the stress or force when the material reaches the plastic state is Fy2. uniaxialMaterial ElasticPP $Tag3 $E3 $epsyP; For an elastic-plastic uniaxial material Tag3, the strain or deformation of the material when it reaches the plastic state under tension is epsyP, with a slope of E3. uniaxialMaterial Parallel $Tag4 $Tag1 $Tag2; Material Tag1 and material Tag2 are combined in parallel to obtain a new material Tag4; uniaxialMaterial Parallel $Tag5 $Tag3 $Tag4; Material Tag3 and material Tag4 are combined in parallel to obtain a new material Tag5; (3) The torsional response of GINA waterstop in the transverse and vertical directions is simulated using an elastic uniaxial material, and the specific definitions are as follows: uniaxialMaterial Elastic $Tag $E; The label for elastic uniaxial materials is Tag, with a slope of E.

3. The numerical simulation method for immersed tunnel segment joints based on nanofluid vibration reduction as described in claim 2, characterized in that step 4 includes the following: The energy dissipation of nanofluid materials is approximated by a high-damping uniaxial rubber material, as defined below: uniaxialMaterial KikuchiAikenHDR $Tag $tp $ar $hr; The high-damping rubber uniaxial material is designated by Tag, rubber type as tp, rubber area as ar, and rubber height as hr.

4. The application of the numerical simulation method for immersed tunnel joint based on nanofluid vibration reduction as described in claim 3, characterized in that: This method is applied to vibration reduction of pipe joints in immersed tunnels. By installing nanofluid dampers along the x-axis, y-axis, and z-axis between the pipe wall mating ends of adjacent pipe joints, the seismic resistance of the pipe joints can be improved.

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