Method for forecasting dynamic response numerical value of flexible pipe body of real-scale floating tunnel under vertical-inclined combined anchor cable mooring, storage medium and equipment

Abstract

The invention discloses a dynamic response numerical prediction method for a flexible pipe body of a real-scale floating tunnel under vertical-inclined combined anchor cable mooring, a storage medium and equipment, and belongs to the technical field of flexible pipe bodies of floating tunnels. The method aims at solving the problems that an existing model based on free two ends of the floating tunnel neglects the remarkable influence of end constraint on tunnel mechanical behaviors in actual engineering, and related research is carried out for a small-scale experiment model. According to the method, firstly, a wave flow coupling excitation numerical environment model is established, grid division is conducted, then a CFD numerical analysis model of the flexible pipe body of the floating tunnel is established, wave force serves as external excitation, displacement changes of the pipe body are triggered by solving an NS equation and calculating wave pressure and shear force distribution of the surface of the pipe body, and then the stretching state of an anchor cable is influenced. Dynamic adjustment of the tension of the anchor cable is triggered; dynamic relation is formed between vibration of the pipe body and tension of the anchor cable, the tension of the anchor cable is updated in real time according to relative displacement and speed change of the pipe body, and response numerical forecasting is completed.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible pipe bodies of floating tunnels, and in particular relates to a numerical prediction method, storage medium and equipment for dynamic response of a flexible pipe body of a floating tunnel. Background Art

[0002] In recent years, with the rapid development of economy and culture, people's demand for cross-sea interconnection has been further enhanced. However, the construction of traditional cross-sea bridges and submarine tunnels requires a lot of manpower, material and financial resources in the face of wide sea surface and deep seabed, and the construction process is extremely challenging. The new mode of transportation, Submerged Floating Tunnel (SFT), can overcome the many troubles encountered by traditional cross-sea transportation buildings in special sea areas. Compared with traditional structures, SFT avoids complex pier construction and large-scale excavation through suspension design, significantly reducing construction costs and construction time. Its superior structural flexibility makes it show obvious technical advantages in certain special sea areas (especially fjord areas).

[0003] Anchor cable suspension tunnel is one of the most promising suspension tunnel forms. Anchor cables connect the suspension tunnel body to the seabed and provide mooring force for the suspension tunnel. In terms of anchor cable mooring constraints, a single vertical anchor cable can provide strong vertical stiffness, but due to the lack of horizontal constraint stiffness, the tunnel body will produce large horizontal movement under the action of waves and currents; although a single inclined anchor cable has a certain horizontal constraint stiffness, the vertical constraint stiffness is insufficient and will introduce torsional stiffness. Based on this, in order to improve the stability of the suspension tunnel body in the vertical, horizontal, and torsional directions, researchers (such as Kanie, 2010; Faggiano et al., 2016) proposed a vertical-inclined combined anchor cable mooring structure. However, there are few studies on the dynamic response and stability characteristics of the suspension tunnel body under the combined anchor cable mooring constraint, and it is necessary to conduct in-depth research on it.

[0004] Due to its large-span flexible structural characteristics, the suspended tunnel body is prone to large vibration responses under environmental loads such as waves and currents, thus threatening the stability and safety of the suspended pipeline body during normal operation. For the suspended tunnel body under the constraints of vertical-inclined combined anchor mooring, accurately predicting its structural dynamic response characteristics under wave and current combined excitation, and carrying out structural optimization design based on the structural vibration response characteristics, thereby improving structural stability and safety, is the key prerequisite for ensuring the normal and safe operation of the suspended tunnel body.

[0005] There are currently three main methods for studying the dynamic response of the flexible pipe body of a suspended tunnel under wave-current combined excitation: theoretical analysis, model experiment, and numerical simulation. Although the theoretical analysis method has a low computational cost, it is difficult to gain an in-depth understanding of the dynamic response mechanism of the flexible pipe body under complex wave-current loads due to the introduction of some empirical formulas and basic assumptions. Although the model experiment can provide intuitive results, it is difficult to fully reveal the complex vibration response characteristics of the real-scale suspended tunnel pipe body due to the scale effect. At the same time, the experimental research cost is high. Compared with theoretical analysis and model experiment methods, the numerical simulation method has unique advantages, especially the CFD numerical method that has developed rapidly in recent years. It can not only efficiently realize fluid-solid coupling and multi-physical field coupling at a low cost, but also accurately analyze the dynamic response characteristics of the three-dimensional flexible pipe body of the suspended tunnel under wave-current excitation. Based on the CFD numerical method, researchers can deeply explore the dynamic behavior characteristics of the suspended tunnel pipe body under different environmental loads, and provide more reliable theoretical support for structural design, optimization and safety assessment. Summary of the invention

[0006] In order to solve the problem that the current model based on the freedom of both ends of the suspended tunnel ignores the significant influence of the end constraints on the mechanical behavior of the tunnel in actual engineering, and the relevant research is carried out on small-scale experimental models, so there is a problem that it cannot be directly extended to the real-scale structural model under real constraint conditions.

[0007] A numerical prediction method for dynamic response of a flexible pipe body of a full-scale floating tunnel under vertical-inclined combined anchor cable mooring, comprising:

[0008] Step 1: Establish a wave-current coupling excitation numerical environment model based on the VOF method and force wave elimination technology;

[0009] Step 2: Mesh the suspended tunnel body and environment, including the following steps:

[0010] Step 201, firstly create various component geometric components, including background watershed components, wave propagation area components, overlapping area components that can cover the motion range of the tube body, suspended tunnel tube body components, internal flow field area components and densification area components;

[0011] Step 202, allocating the background watershed component, the overlapping area component, the suspended tunnel body component, and the internal flow field area component to four different areas;

[0012] Step 203, expand the geometry and operate the nodes; then select the cutting volume mesh for the background flow domain, select the polyhedral mesh for the overlapping area, select the directional mesh for the floating tunnel body, and select the directional mesh for the internal flow field area;

[0013] Step 204, first add a volume control for the background basin. In this process, select Create Volume Control and rename the new node as Wave, then input the wave propagation area component; then add an encrypted area grid, rename it as Encrypted and customize the size;

[0014] Step 205, add volume control for the overlapping area. In this process, select New Volume Control, rename the new node to block, then input the block component, select the Cut Volume Mesher node and customize the size;

[0015] Step 206, generate a directional mesh. In this process, select the directional mesh node, rename the generated node to tube body, and then enter the parts and customize the size;

[0016] The same treatment is performed on the internal flow field area;

[0017] Step 207, define overlapping grids; select the background watershed and the overlapping area at the same time, select Create Interface and then select Overlap Grid;

[0018] Step 208, generating all grids;

[0019] Step 3: Establish the CFD numerical analysis model of the floating tunnel flexible pipe body:

[0020] The forces on the suspended tunnel body during operation include anchor cable tension, self-gravity and fluid force, and the fluid force includes wave force. The self-gravity of the suspended tunnel causes it to act downward, and the upward force generated by the buoyancy of the tunnel, the gravity of the tube body and the buoyancy together constitute the initial mechanical balance of the system. Under static water conditions, the anchor cable generates pre-tension by being tightened.

[0021] The vibration response of the suspended tunnel pipe body is determined by the combined effects of fluid force, anchor cable tension, self-gravity and buoyancy. Wave force is used as an external excitation. The NS equation is solved by CFD method to calculate the wave pressure and shear force distribution on the pipe surface. Wave pressure and shear force excite vibration and cause displacement changes. The displacement change of the pipe body affects the tensile state of the anchor cable, which triggers the dynamic adjustment of the anchor cable tension. The change of anchor cable tension is the result of the vibration of the pipe body caused by wave force. At the same time, the anchor cable tension limits the amplitude of the pipe body vibration through the reaction force. Through the anchor cable-pipe coupling vibration equation, a dynamic connection is formed between the pipe body vibration and the anchor cable tension. The anchor cable tension is updated in real time according to the relative displacement and velocity change of the pipe body. The anchor cable tension, self-gravity, buoyancy and wave force maintain the dynamic balance of the suspended tunnel pipe body. In STAR-CCM+, based on the combined anchor cable suspended tunnel model, wave force causes pipe body vibration, and the anchor cable tension feeds back and adjusts the displacement and vibration of the pipe body in real time, while gravity and buoyancy participate in maintaining the mechanical balance of the system. The wave force, anchor cable tension and the displacement of the pipe body interact with each other in continuous iteration and update to form an integrated numerical model of the vibration response of the suspended tunnel.

[0022] Finally, according to the flow field conditions of the wave-current coupling excitation numerical environment model set previously, the entire flow field is initialized, and the appropriate calculation step size is selected according to the calculation requirements to start the numerical simulation.

[0023] Furthermore, in the process of calculating the wave pressure and shear force distribution on the pipe surface, the wave pressure in, is the pressure exerted by the wave at position x and depth z, where x is the horizontal position, z is the coordinate perpendicular to the sea surface, and t is time; ρ is the fluid density, g is the acceleration due to gravity, A is the amplitude of the wave; h is the water depth; k is the wave number, and ω is the angular frequency of the wave.

[0024] Furthermore, the wave number k=2π / λ, wherein λ is the wavelength.

[0025] Furthermore, the anchor cable-tube coupling vibration equation is as follows:

[0026]

[0027] Where ρ is the density of the fluid; C L is the lift coefficient; v is the flow velocity; θ is the inclination angle of the anchor cable; ω v is the vortex discharge frequency; L is the length of the anchor cable; D t is the diameter of the anchor cable; is the sum of the mass of the anchor cable per unit length and the additional water mass; D n Symbols introduced for the convenience of calculation, y is the lateral displacement of the anchor cable, and They represent the lateral velocity and acceleration of the anchor cable respectively; n is the order; c is the viscous damping coefficient of the anchor cable; A1 is the cross-sectional area of ​​the anchor cable; E eq is the equivalent elastic modulus; Z is the vibration displacement of the tube body, and are the vibration velocity and acceleration respectively; ω1 is the natural frequency of the anchor cable; ω2 is the natural frequency of the pipe body; ξ2 is the damping ratio of the pipe body; M is the mass of the suspended tunnel.

[0028] Furthermore, the construction process of the combined anchor cable suspended tunnel model includes:

[0029] (1)Import file:

[0030] Open the STAR CCM+ software and import the mesh file obtained in step 2;

[0031] (2)Selection Physical Model:

[0032] First, create a fluid physical continuum, namely physical continuum 1, and select the following models in order: three-dimensional, implicit unsteady, multiphase, multiphase interaction, fluid volume, turbulence model, SST K-Omega model, gradient, separated flow, multiphase equation of state, and check gravity, VOF wave, and adaptive time step in the optional models, and finally click OK; then create a solid physical continuum, namely physical continuum 2, select three-dimensional, implicit unsteady, solid, solid stress, Rayleigh damping, flexible DFBI motion, and gravity model, and finally click OK;

[0033] (3)Define the flexibleDFBI movement:

[0034] Click Tools > Motion Node, right-click the Motion node, and then select New > DFBI Deformation. A new node named DFBI Deformation is added to the Motion Manager; the “>” indicates the next step.

[0035] (4)Edit 6-DOF volume parameters:

[0036] Select Region > Overlap Region > Physical Value > Motion Assignment node, set the motion to DFBI deformation; then right-click the DFBI > 6-DOF Body node and select New Body > 3D > Continuum; rename the newly created node to Tube; then right-click Tube > Create Body Motion, create a new node named Tube-motion under the Motion node, and create a new solid displacement in the Tube-motion node for backup;

[0037] (5)Model parameter setting:

[0038] Select DFBI>6 DOF Body>Tube Body node with the mouse, add moving parts and suspension tunnel mass under this node; check the motion properties of X-axis movement, Z-axis movement and Y-axis rotation in the Free Motion node; customize the moment of inertia and center of mass of the suspension tunnel in the Initial Value node;

[0039] (6)Define the motion of the SubmergedFloating Tunnel:

[0040] Select the Region > Suspension Tunnel Body > Physical Conditions > Flexible DFBI Motion Options node, and set the Flexible DFBI Motion Options to DFBI-Partially deformable; in the Suspension Tunnel Body > Physical Values ​​> Motion Assignment node, set the motion to Body-motion-Solid Displacement; then in the Suspension Tunnel Solid > Segment node, set the two end faces to Fixed Constraints;

[0041] (7)Define the internal flow field regional motion:

[0042] Select Region > Internal Flow Region > Physical Values ​​> Motion Assignment node and set the motion to DFBI deformation;

[0043] (8)Create interface:

[0044] The surface where the outer wall of the tube body contacts the flow field and the surface where the inner wall of the tube body contacts the air flow field are respectively set as the phase contact interface; the operation method is similar to the method of creating an overlapping grid;

[0045] (9)Add the anchor cable to the body coupling module:

[0046] Right-click DFBI > Body Coupling node and add the required anchor cables, including spring-damper, catenary and other contact forms;

[0047] (10)Solver setup:

[0048] Click Solver > Implicit Unsteady State and set the required time step. Then click the 6 DOF Mesh Deformation node and check Zero Deformation, Recalculate Interfaces, Boundary Layer Deformation, and Keep Temporary Storage to meet the deformation requirements.

[0049] (11)Stop criterion setting:

[0050] Click the Stop Criteria node, uncheck the Displacement Criterion, Force Criterion, Maximum Steps, and Stop File functions, then set the number of iterations in the Maximum Inner Iterations node and the running time in the Maximum Physical Time node;

[0051] (12)Initialize Solution andRun Calculation:

[0052] First click the Initialize Solution button with the mouse, then click the Run button to start the simulation calculation.

[0053] Furthermore, the multiphase in step (2) is a gas-liquid two-phase flow.

[0054] Furthermore, in the step (2), in the process of selecting the fluid volume, wave loads are introduced, and flow is added on this basis to reflect the influence of wave and flow on the vibration of the pipe body;

[0055] The wave loads are as follows:

[0056] Horizontal speed of the wave:

[0057] u(x,t)=Aωcosh(k(z+h))cos(kx-ωt)

[0058] Among them, A is the amplitude of the wave; ω is the angular frequency of the wave; k is the number of waves; h is the water depth; z is the coordinate perpendicular to the sea surface; t is time; x is the horizontal position;

[0059] Surface wave pressure:

[0060]

[0061] in, is the pressure exerted by the wave; g is the acceleration due to gravity; η is the deformation of the wave surface; is the rate of change of water surface over time;

[0062] Wave pressure inside the fluid:

[0063]

[0064] in, is the pressure exerted by the wave at position x and depth z, where x is the horizontal position, z is the coordinate perpendicular to the sea surface, and t is time; ρ is the fluid density, g is the acceleration due to gravity, A is the amplitude of the wave; h is the water depth; k is the wave number, and ω is the angular frequency of the wave.

[0065] Furthermore, in the step (9), in the process of adding the required anchor cables, an anchor cable-tube coupling effect is introduced; the anchor cable-tube coupling effect is realized by an anchor cable-tube coupling vibration equation;

[0066] The anchor cable-tube coupling vibration equation is as follows:

[0067]

[0068] Where ρ is the density of the fluid; C L is the lift coefficient; v is the flow velocity; θ is the inclination angle of the anchor cable; ω v is the vortex discharge frequency; L is the length of the anchor cable; D t is the diameter of the anchor cable; is the sum of the mass of the anchor cable per unit length and the additional water mass; D n Symbols introduced to facilitate calculations: CD =0.7 is the drag coefficient, z is the integral variable; y is the lateral displacement of the anchor cable, and They represent the lateral velocity and acceleration of the anchor cable respectively; n is the order; c is the viscous damping coefficient of the anchor cable; A1 is the cross-sectional area of ​​the anchor cable; E eq is the equivalent elastic modulus; Z is the vibration displacement of the tube body, and are the vibration velocity and acceleration respectively; ω1 is the natural frequency of the anchor cable; ω2 is the natural frequency of the pipe body; ξ2 is the damping ratio of the pipe body; M is the mass of the suspended tunnel.

[0069] A computer storage medium stores a computer program, which is loaded and executed by a processor to provide a numerical prediction method for dynamic response of a flexible pipe body of a real-scale floating tunnel under a vertical-inclined combined anchor cable mooring.

[0070] A device for numerically predicting the dynamic response of a flexible pipe body of a real-scale floating tunnel under vertical-inclined combined anchor cable mooring. The device comprises a processor and a memory. A computer program is stored in the memory. The computer program is loaded and executed by the processor to implement a method for numerically predicting the dynamic response of a flexible pipe body of a real-scale floating tunnel under vertical-inclined combined anchor cable mooring.

[0071] Beneficial effects:

[0072] The present invention designs a new method for numerical prediction of dynamic response of a flexible pipe body of a large-span suspended tunnel under wave-current combined excitation under a vertical-inclined combined anchor cable mooring. This method can more reliably simulate the complex vibration response characteristics of a flexible pipe body of a full-scale suspended tunnel under wave-current combined excitation. Compared with the prior art, the technical solution of the present invention has the following advantages:

[0073] 1. In order to simplify the analysis, traditional studies often assume that both ends of the suspended tunnel are free. Although this reduces the complexity of the model, it ignores the significant impact of the end constraints on the mechanical behavior of the tunnel in actual engineering. And most of the relevant research is carried out on small-scale experimental models. The simplification of boundary constraints and the reduction of scale models result in the conclusions obtained based on traditional research being unable to be directly extended to real-scale structural models under real constraints. To this end, the present invention provides a new research perspective and research framework for the study of the dynamic response characteristics of the flexible pipe body of a real-scale suspended tunnel under complex environmental loads by introducing real end constraints and a real-scale flexible pipe body of a suspended tunnel.

[0074] 2. Most of the current studies simplify the mooring constraints of the suspended tunnel into a single vertical or inclined mooring anchor model. Although this improves the calculation efficiency, it cannot reflect the complex mooring constraints. The hybrid anchor layout combines the structural characteristics of vertical and inclined anchors, resulting in better stability characteristics both vertically and horizontally compared to the single mooring anchor constraint. However, there are few studies on the hybrid anchor layout, especially the dynamic response mechanism of this layout structure under the combined excitation of waves and currents is still unclear. To this end, the present invention innovatively proposes a numerical prediction method, which can reliably analyze the dynamic response characteristics of the flexible pipe body of the suspended tunnel under the vertical-inclined combined anchor mooring constraint. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 This is the flow chart of numerical simulation of wave-current joint excitation;

[0076] Figure 2 Schematic diagram of the grid of each component;

[0077] Figure 3 Schematic diagram of the numerical model of the suspended tunnel under wave-current combined excitation (front view);

[0078] Figure 4 Schematic diagram of the numerical model of the suspended tunnel under wave-current combined excitation (side view);

[0079] Figure 5 It is the time history curve of the wave surface at 0m;

[0080] Figure 6 It is the time history curve of the wave surface at -100m;

[0081] Figure 7 It is the time history curve of the wave surface at 100m;

[0082] Figure 8 It is a wave-current coupled numerical environmental model;

[0083] Fig. 9 It is the sway time history curve at y = 1 / 4L;

[0084] Fig.10 It is the heave time history curve at y = 1 / 4L;

[0085] Fig.11 It is the sway time history curve at y = 1 / 2L;

[0086] Fig.12 It is the heave time history curve at y = 1 / 2L;

[0087] Fig.13 It is the sway time history curve at y=3 / 4L;

[0088] Fig.14It is the heave time history curve at y=3 / 4L;

[0089] Fig.15 The anchor chain force curve is tilted to the back sea;

[0090] Fig.16 The anchor chain force curve is tilted towards the sea;

[0091] Fig.17 is the vertical anchor chain force curve in the back sea;

[0092] Fig.18 This is the vertical anchor chain force curve facing the sea. DETAILED DESCRIPTION

[0093] In view of the problems existing in the background technology, the present invention innovatively proposes a numerical prediction method for the dynamic response of the flexible pipe body of a large-span suspended tunnel under the constraints of a vertical-inclined combined anchor mooring under the combined excitation of waves and currents. This numerical method can more accurately simulate the dynamic behavior characteristics of the flexible pipe body of the suspended tunnel under loads in a complex environment, providing a reliable theoretical basis and technical support for the design and optimization of the suspended tunnel. Specific implementation method one:

[0095] This embodiment is a method for numerically predicting the dynamic response of a flexible pipe body of a full-scale floating tunnel under vertical-inclined combined anchor cable mooring, comprising the following steps:

[0096] Step 1: Establish a numerical environment model for wave-current coupling excitation:

[0097] When conducting numerical research on the dynamic response of a suspended tunnel under wave-current combined excitation, it is key to establish an accurate numerical environment model of wave-current coupled excitation. The present invention constructs a wave-current coupled excitation numerical environment model combining the VOF method and force wave elimination technology, which can accurately simulate the interaction between waves and fluids and their impact on suspended tunnels.

[0098] The VOF method is used to simulate the change of the two-phase flow surface to realize wave simulation, and then a numerical water pool is constructed; in the process of simulating the change of the two-phase flow surface by the VOF method to realize wave simulation, based on the viscous flow theory, the velocity field, pressure field and other flow characteristics of the wave and fluid are obtained by solving the NS equation, and then the vibration response characteristics of the suspended tunnel are obtained. This process can be carried out using the existing technology, and the present invention will not be described in detail.

[0099] At the boundary of the numerical water pool, in order to reduce the influence of boundary reflection waves, the present invention introduces a wave-breaking zone. Taking into account the accuracy and computational efficiency of wave numerical simulation, we chose the force wave-breaking method. This method can effectively reduce the calculation domain while eliminating reflection waves by setting boundary resistance, thereby reducing the demand for computing resources. Compared with traditional damping wave breaking, force wave breaking has a stronger wave elimination ability and can maintain a relatively stable calculation effect during wave propagation. The calculation domain size and mesh division of the wave-flow numerical environment are crucial to the accuracy of the simulation results. According to the theoretical predictions of different wave surface lift heights, the present invention adjusts the size of the calculation domain and performs preliminary mesh division on the numerical water pool to ensure the accuracy of the wave simulation. On this basis, by comparing the simulated wave surface with the theoretical wave surface, the mesh division scheme is optimized to ensure that the propagation characteristics and structural responses of the waves during the simulation process are accurately reflected, providing an effective numerical tool for the dynamic response analysis of the suspended tunnel under wave and flow excitation. The detailed research plan is as follows. Figure 1 shown.

[0100] Step 2: Overlapping grid, directional grid and other component grid divisions:

[0101] First, a series of parameters are determined, including the style and size of the suspended tunnel body, the elastic modulus E of the anchor cable, and the c , Anchor cable length L c , Submergence depth H s , flow velocity U, water depth H w , wave height H and wave period T, etc., and then grid division is carried out.

[0102] The meshing process is as follows:

[0103] In the present invention, for the dynamic response of a large-span suspended tunnel under the combined excitation of waves and currents, multiple grid types such as cut-body grids, polyhedron grids and directional grids are used for grid division. In order to accurately simulate and capture the movement and deformation of the suspended tunnel, the overlapping grid method is selected for subsequent simulation. Among them, the cut-body grid is used in the wave-current action area to accurately capture the propagation of waves and the changes of the free surface. For the dynamic area of ​​the suspended tunnel, that is, the moving part of the tube body under the action of waves and currents, the overlapping grid technology is used, and the overlapping grid adopts the polyhedron grid type. This technology can effectively capture the movement and deformation of the tunnel, especially when dealing with the interaction between the tunnel surface and the fluid, it ensures higher calculation accuracy. The solid part of the tunnel and the internal air flow field use directional grids to ensure the accurate simulation of the structural details, and through the uniformity of the directional grid, the grid consistency of each section is guaranteed, thereby improving the calculation efficiency and accuracy of the grid. Through the optimized combination of this grid technology, it is possible to more effectively deal with the complex flow and structural dynamic response under the combined excitation of waves and currents.

[0104] Taking the classic circular cross-section suspension tunnel body as an example, the grid division method of each component to be used in the present invention is as follows: Figure 2 shown.

[0105] Using the powerful meshing function of STAR CCM+ software, the meshing steps of each component are as follows:

[0106] 1. First, create the geometric components of each component, including the background basin component, the wave propagation area component, the overlapping area component that can cover the movement range of the pipe body, the suspended tunnel body component, the internal flow field area component and the encrypted area component to ensure that the model meets the analysis requirements.

[0107] It should be noted that: in order to be closer to the actual use environment of the suspended tunnel, the present invention performs numerical prediction of the dynamic response of the flexible pipe body. In this case, the overlapping area is the part where the motion range of the suspended tunnel pipe body overlaps with the background area. This area can be larger or smaller, but at least it must be able to cover the motion range of the pipe body. It should also be noted that, precisely because the present invention is for the numerical prediction of the dynamic response of the flexible pipe body of the suspended tunnel, although CFD software / toolkit is used, the CFD-based modeling and fluid dynamics calculations need to be performed according to actual fluid dynamics factors. Therefore, how to model, how to set up, and how to perform numerical analysis will seriously affect the effect of the fluid dynamics calculation, thereby seriously affecting the numerical prediction results of the dynamic response of the pipe body.

[0108] 2. Allocate the background watershed components, overlapping area components, suspended tunnel body components, and internal flow field area components to four different areas.

[0109] 3. Expand the Geometry > Operations node. The “>” indicates the next operation. Then do the following: select the cut volume mesh for the background flow domain; select the polyhedral mesh for the overlap region; select the directional mesh for the floating tunnel body; select the directional mesh for the internal flow field region.

[0110] 4. Add volume control for the background flow domain. Right-click Geometry > Operations > Background Flow Domain > Custom Control, then select New > Volume Control, rename the new node to Wave, then enter the wave propagation area component, select Wave > Control > Cut Volume Mesher Node > Custom Anisotropic Size. Then customize the relative size (X), relative size (Y), and relative size (Z). The relative size (X) and relative size (Y) are generally set to 1 / 80-1 / 100 of the wavelength, and the relative size (Z) is generally set to 1 / 10-1 / 20 of the wave height. Then add a mesh for the encryption area, rename it to Encryption, select Encryption > Control > Cut Volume Mesher Node > Custom Isotropic Size, and then customize the size. If there are multiple encryption areas, repeat this step.

[0111] 5. Add volume control for the overlap region. Right-click Geometry > Operation > Overlap Region > Custom Control, then select New > Volume Control, rename the new node to block, then import the block component, select block > Control > Cut Volume Mesher Node > Custom Isotropic Size, then customize the size. If you want to refine the surface mesh, just select the surface control, and the other steps are the same as the above volume control.

[0112] 6. Generate a directional mesh. Right-click > Mesh > Directed Mesh Node, rename the generated node to Tube Body, then enter the component, customize the size, and then select Tube Body > Mesh Distribution > Layers Node to define the required number of mesh layers for the tube body. The directional mesh required for the internal flow field area is the same as above.

[0113] 7. Define the overlapping grid. Select the background watershed and the overlapping area at the same time, right-click, and select Create Interface > Overlap Grid.

[0114] 8. Generate all meshes. Right-click the operation node and select Execute All Operations.

[0115] Step 3: Establish the CFD numerical analysis model of the floating tunnel flexible pipe body:

[0116] The suspended tunnel body is subject to a variety of forces during operation, mainly including anchor tension, self-gravity and fluid force. First, the self-gravity of the suspended tunnel causes it to act downward, while the upward force generated by the buoyancy of the tunnel counteracts its gravity. Under static water conditions, the tunnel is fixed to the bottom of the water by anchor cables, which generate pre-tension by tightening. The magnitude of this pre-tension is equal to the difference between the buoyancy and gravity of the tunnel section, and it is an important factor in ensuring the stability of the tunnel. In addition, fluid forces (including waves, ocean currents, etc.) exert dynamic forces on the tunnel. Especially under the excitation of waves and water currents, the tunnel will experience different vibration responses. These dynamic forces may affect the stability and operational safety of the tunnel. Therefore, the design and analysis of the suspended tunnel must take into account the combined effects of the above-mentioned forces, especially the tension of the anchor cables must always be maintained to ensure that the tunnel does not float up or become unstable.

[0117] 1. Navier-Stokes (NS) equations:

[0118] Mass conservation equation: (continuity equation)

[0119] ▽·u=0(for incompressible fluid) (1) Momentum conservation equation:

[0120]

[0121] Among them, u is the fluid velocity; p is the pressure; ρ is the fluid density; μ is the fluid viscosity coefficient; f is the external force (such as gravity).

[0122] 2. Wave load:

[0123] According to linear wave theory, wave loads are expressed by wave amplitude, wavelength, period and other parameters. If a sinusoidal wave is considered, the horizontal velocity and pressure of the wave can be expressed as:

[0124] Horizontal speed of the wave:

[0125] u(x,t)=Aωcosh(k(z+h))cos(kx-ωt) (3)

[0126] Among them, A is the amplitude of the wave; ω is the angular frequency of the wave; k is the wave number, k = 2π / λ (where λ is the wavelength); h is the water depth; z is the coordinate perpendicular to the sea surface (the positive direction points upward); t is the time; and x is the horizontal position.

[0127] Wave pressure is the pressure caused by the surface undulation of water waves. Surface wave pressure is estimated using the linear theory of waves:

[0128]

[0129] in, is the pressure exerted by the wave; g is the acceleration due to gravity; η is the wave surface deformation (i.e. the height of the water surface); is the rate of change of water surface with time.

[0130] Pressure exerted by waves considering water depth (deep water area):

[0131]

[0132] in, is the pressure exerted by the wave at position x and depth z, and its variation is related to the water depth and the propagation of the wave.

[0133] 3. Anchor cable-pipe coupling:

[0134] The coupled vibration equation of anchor cable and pipe body can be expressed as follows:

[0135]

[0136] Where, ρ = 1028 kg / m 3 ; C L is the lift coefficient, take C L =0.6; v is the flow velocity; θ is the inclination angle of the anchor cable; ω v is the vortex discharge frequency; L is the length of the anchor cable; D t is the diameter of the anchor cable; is the sum of the mass of the anchor cable per unit length and the additional water mass; D n Symbols introduced to facilitate calculations: C D =0.7 is the drag coefficient, z is the integral variable; y is the lateral displacement of the anchor cable, and They represent the lateral velocity and acceleration of the anchor cable respectively; n is the order; c is the viscous damping coefficient of the anchor cable; A1 is the cross-sectional area of ​​the anchor cable; E eq is the equivalent elastic modulus; Z is the vibration displacement of the tube body, and are the vibration velocity and acceleration respectively; ω1 is the natural frequency of the anchor cable; ω2 is the natural frequency of the pipe body; ξ2 is the damping ratio of the pipe body; M is the mass of the suspended tunnel.

[0137] In equations (6) and (7), the vibration of the suspended tunnel causes periodic changes in the tension of the anchor cable, which in turn affects the anchor cable stiffness and the coefficient of the first-order term y in the vibration equation, causing the vibration of the anchor cable to be parametrically excited. When the natural frequency of the anchor cable is close to half of the tunnel vibration frequency, parametric resonance will occur, causing the anchor cable to vibrate laterally with large amplitude. At this time, the system exhibits nonlinear coupled vibration, which contains linear and nonlinear terms, reflecting the complex relationship between the tunnel vibration and the dynamic coupling of the anchor cable. Figure 3-Figure 4 Schematic diagram of the numerical model of the suspended tunnel under wave-current combined excitation.

[0138] The vibration response of the suspended tunnel pipe is determined by the combined effects of fluid force (wave force), anchor cable tension, self-gravity and buoyancy. These forces form the system's equilibrium mechanism through complex dynamic interactions. Wave force is used as an external excitation. The Navier-Stokes (NS) equation is solved by the CFD method to calculate the wave pressure (Formula (5)) and shear force distribution on the pipe surface. These wave loads act directly on the pipe, exciting vibration and causing displacement changes. The displacement change of the pipe further affects the tensile state of the anchor cable, thereby triggering the dynamic adjustment of the anchor cable tension. The change in anchor cable tension is not only the result of the vibration of the pipe caused by wave force, but also limits the amplitude of the pipe vibration through the reaction force and maintains the dynamic balance of the system. Through this anchor cable-pipe coupling (Formula (6)-(7)) feedback mechanism, a close dynamic connection is formed between the pipe vibration and the anchor cable tension, in which the anchor cable tension is updated in real time according to the relative displacement and velocity change of the pipe, providing the necessary constraints and stability for the system.

[0139] In addition, the gravity and buoyancy of the pipe body together constitute the initial mechanical balance of the system. Gravity causes the pipe body to sink, and buoyancy provides part of the upward moment. The state of balance between the two provides basic support for the dynamic action of anchor cable tension and wave force. The combined action of gravity, buoyancy, anchor cable tension and wave force determines the overall vibration characteristics of the system under the combined excitation of waves and currents.

[0140] In STAR-CCM+, this process is achieved through continuous dynamic interaction. Wave force causes the pipe to vibrate, and the anchor tension provides feedback and adjusts the displacement and vibration of the pipe in real time, while gravity and buoyancy participate in maintaining the mechanical balance of the system. The wave force, anchor tension, and pipe displacement interact with each other in continuous iteration and update, ultimately forming an integrated numerical model of the vibration response of the suspended tunnel. This model not only accurately simulates the dynamic characteristics of the pipe under the combined excitation of waves and currents, but also provides a scientific basis for the optimal design and operational stability of the suspended tunnel.

[0141] Construction of combined anchor cable suspended tunnel model:

[0142] First, import the preset grid file into the STAR CCM+ software and create a physical model of the fluid. In the model settings, select options such as three-dimensional, multiphase, implicit unsteady state, and adaptive time step. The turbulence model uses the separated flow and SST (Menter) K-Omega model. The multiphase model of the fluid uses the VOF (Volume of Fluid) method, and the gravity acceleration is set to -9.81m / s 2 In the VOF wave node, a fifth-order wave is defined as a wave excitation source. The multiphase model of the fluid in the present invention is a gas-liquid two-phase flow.

[0143] Next, create a physical model of the suspended tunnel body, use an isotropic linear elastic body model, and check the settings of 3D, solid, solid stress, Rayleigh damping, flexible DFBI motion, gravity, and implicit unsteady state. Then, create a DFBI deformation model through the "Motion" node in the toolbar, and configure the relevant parameters in the newly generated DFBI node.

[0144] It should be noted that in the dynamic analysis of the flexible pipe body of the suspended tunnel, solid stress, Rayleigh damping and flexible DFBI motion are key modules. The combination of the three can truly simulate the dynamic behavior of the pipe body in a complex environment. Solid stress is used to describe the stress distribution and deformation characteristics inside the pipe body. Rayleigh damping effectively suppresses high-frequency vibrations by simulating material energy dissipation. Flexible DFBI motion gives the pipe body the ability to deform freely, realizing the dynamic coupling of fluid force and pipe body vibration, thereby fully reflecting the complex dynamic response of the pipe body under wave and flow excitation.

[0145] Compared with the rigid pipe body assumption in traditional research, the present invention highlights the flexible characteristics of the pipe body. Existing studies usually use rigid DFBI modules, which are difficult to accurately reflect the deformation and actual dynamic response of the pipe body. By combining the flexible DFBI motion, solid stress and Rayleigh damping models, the present invention can not only simulate the vibration and deformation of the pipe body under wave and flow excitation, but also capture the influence of flexible characteristics on vibration and energy dissipation, providing a more realistic and comprehensive analysis method for the dynamic study of the flexible pipe body of the suspended tunnel in a complex environment.

[0146] Finally, according to the flow field conditions of the numerical environment model with wave-current coupling excitation set previously, the entire flow field is initialized, and the appropriate calculation step size is selected according to the calculation requirements to start the numerical simulation.

[0147] The specific steps for constructing the combined anchor cable suspended tunnel model are as follows:

[0148] (1)Import file

[0149] Open the STAR CCM+ software, select the appropriate number of working cores, and import the preset grid file.

[0150] (2)Selection Physical Model

[0151] First, create a fluid physics continuum, Continuum>Physics 1, select the following models in order: 3D, Implicit Unsteady, Multiphase, Multiphase Interaction (Automatic selection), Volume of Fluid (VOF), Turbulence Model, SST (Menter) K-Omega Model, Gradient (Automatic selection), Separated Flow (Automatic selection), Multiphase Equation of State (Automatic selection), and check Gravity, VOF Wave, Adaptive Time Step in the optional models, and finally click OK. Then create a solid physics continuum, Continuum>Physics 2, select 3D, Implicit Unsteady, Solid, Solid Stress, Rayleigh Damping, Flexible DFBI Motion, Gravity Model, and finally click OK.

[0152] Note: By using the VOF wave model to simulate the wave propagation process, a basic support is provided for studying the vibration response of the pipe under wave-current combined excitation. In this model, the wave load (formula (3)-(5)) is accurately introduced, and the flow is added on this basis to reflect the influence of wave and current on the vibration of the pipe, laying a key foundation for the subsequent vibration characteristics analysis.

[0153] (3)Define the flexibleDFBI movement

[0154] Click Tools > Motion Node, right-click the Motion node, and select New > DFBI Deformation. A new node named DFBI Deformation is added to the Motion Manager.

[0155] (4)Edit 6-DOF volume parameters

[0156] Select Region > Overlap Region > Physical Value > Motion Assignment node, set the motion to DFBI deformation. Then right-click the DFBI > 6 DOF Body node and select New Body > 3D > Continuum. Rename the newly created node to Tube. Then right-click Tube > Create Body Motion, create a new node named Tube-motion under the Motion node, and create a new solid displacement in the Tube-motion node for future use.

[0157] (5)Model parameter setting

[0158] Select DFBI>6DOF Body>Tube Body node with the mouse, and add the moving parts and suspension tunnel mass under this node. In the Free Motion node, check the motion properties of X-axis movement, Z-axis movement, and Y-axis rotation. In the Initial Value node, customize the moment of inertia and center of mass of the suspension tunnel.

[0159] (6)Define the motion of the SubmergedFloating Tunnel

[0160] Select the Region > Floating Tunnel Body > Physical Conditions > Flexible DFBI Motion Options node, and set the Flexible DFBI Motion Options to DFBI-Partially deformable. In the Floating Tunnel Body > Physical Values ​​> Motion Assignment node, set the motion to Body-motion-Solid Displacement. Then in the Floating Tunnel Solid > Segment node, set the two end faces to Fixed Constraints.

[0161] It should be noted that the present invention adopts a flexible DFBI-partially deformable mode to enable the tube body to achieve local deformation under the combined excitation of waves and currents while maintaining overall stiffness, thereby accurately simulating its dynamic behavior. The "tube body-motion-solid displacement" motion type is creatively set to ensure that the dynamic response conforms to the actual law; at the same time, the fixed constraints at both ends are combined as boundary conditions to truly reproduce the fixed state of the suspended tunnel, providing a reliable basis for simulation close to the actual working conditions.

[0162] Different from the rigid body DFBI translation motion or flexible body deformation motion settings commonly used in existing research, the "tube-motion-solid displacement" motion can not only simulate the overall motion of the tube, but also accurately calculate its local deformation and displacement characteristics. Traditional deformation motion settings are difficult to meet both requirements at the same time, and the present invention effectively makes up for the shortcomings of the existing model through this method, providing a more scientific and comprehensive solution for the real dynamics research of the suspended tunnel tube under wave-current combined excitation.

[0163] (7)Define the internal flow field regional motion

[0164] Select Region > Interior Flow Region > Physics Values ​​> Motion Assignment node and set the motion to DFBI deformation.

[0165] (8)Create interface

[0166] The surface where the outer wall of the tube body contacts the flow domain and the surface where the inner wall of the tube body contacts the air flow field are set as the phase contact interface. The operation method is similar to the method of creating an overlapping grid.

[0167] (9)Add the anchor cable to the body coupling module

[0168] Right-click the DFBI > Body Coupling node and add the required anchor cables, including spring-damper, catenary, and other contact forms.

[0169] Note: Here, we add anchor cables to the model and introduce the anchor cable-tube coupling effect to simulate the restriction and regulation effect of the anchor cables on the movement of the suspended tunnel tube (Formula 6-7), so as to more realistically reflect its dynamic behavior.

[0170] (10)Solver setup

[0171] Click on the Solver > Implicit Unsteady node and set the desired time step. Then click on the 6 DOF Mesh Deformation node and check Zero deformation, Recalculate interfaces, Boundary layer deformation, and Keep temporary storage to meet the deformation requirements.

[0172] (11)Stop criterion setting

[0173] Click the Stop Criteria node and uncheck the Displacement Criterion, Force Criterion, Maximum Steps, and Stop File functions. Then set the number of iterations in the Maximum Inner Iterations node and the running time in the Maximum Physical Time node.

[0174] (12)Initialize Solution andRun Calculation

[0175] First click the Initialize Solution button with the mouse, then click the Run button to start the simulation calculation.

[0176] Example:

[0177] The above process is used for numerical calculation and analysis. So far, no underwater suspended tunnel has been built in the world. The present invention is based on the conceptual model of Qiandao Lake suspended tunnel, and the dimensions corresponding to the construction model are selected for vibration response analysis. The selection of numerical analysis parameters for suspended tunnel is shown in Table 1. The following is a specific implementation path:

[0178] Table 1 Selection of parameters for numerical analysis of suspended tunnel

[0179]

[0180] (1) Construct the corresponding numerical environment model of wave-current coupling excitation:

[0181] Figure 5-Figure 7 By comparing the theoretical and actual values ​​of wave surface lift height at three positions, namely 0m, -100m and 100m, it was found that the waves were very stable, which was in line with expectations, reflecting the reliability of the wave numerical pool.

[0182] (1) Vibration response analysis:

[0183] Referring to the actual suspension tunnel structural parameters in Table 1, a wave-current coupled numerical environmental model with a total length of 300 m, a width of 210 m, and a height of 200 m was established. The selected waves were: wave height of 6 m, period of 8 s, wavelength of 105 m, and flow velocity of 1 m / s. The wave-current coupled vibration response analysis was carried out on a suspension tunnel with a length of 200 m, a diameter of 15 m, and a wall thickness of 1 m. Figure 8 It is a wave-current coupled numerical environment model.

[0184] The numerical simulation results of the dynamic response of the combined anchor cable moored floating tunnel under wave and current combined excitation are as follows: Fig. 9 The lateral sway time history curve of the suspended tunnel body at y = 1 / 4L, Fig.10Heave time history curve at y = 1 / 4L, Fig.11 The horizontal swing time history curve at y = 1 / 2L, Fig.12 From the heave time history curve at y=1 / 2L, it can be seen that the lateral and heave vibration response values ​​are different at different cross-sectional locations, reflecting the flexible characteristics of the pipe body, which is in line with expectations. Fig. 9 The lateral sway time history curve of the suspended tunnel body at y = 1 / 4L and Fig.13 The horizontal swing history curve at y = 3 / 4L, Fig.10 The heave time history curve at y = 1 / 4L and Fig.14 From the heave time history curve at y=3 / 4L, it can be seen that the vibration response at the symmetrical position of the pipe body is symmetrical, which is consistent with the actual situation. Fig.15 Back wave tilt anchor chain force, Fig.16 Anchor chain force tilting against the sea, Fig.17 Vertical anchor chain force due to back wave, Fig.18 From the vertical anchor chain force facing the waves, it can be seen that the combined anchor cable mooring has a good restraining effect on the vibration response of the pipe body, and the vibration response of the pipe body shows a certain regularity over time.

[0185] Researchers can use the above method to carry out large-scale numerical simulations by precisely adjusting the key structural parameters of the suspended tunnel, such as the submergence depth, the angle of the inclined anchor cables, etc., and considering variable environmental loads such as waves and currents. Through in-depth analysis of the simulation data, the dynamic response characteristics of the long-span suspended tunnel under the combined action of waves and currents under complex constraints can be revealed. This study uses a more detailed wave-current joint excitation simulation, which can more realistically reflect the vibration and deformation behavior of the flexible tunnel structure in the actual environment. The research results provide important theoretical basis and technical support for the design, construction, operation management and safety monitoring of long-span suspended tunnels in complex marine environments, which helps to optimize the structural configuration of the tunnel and improve its anti-disturbance ability, ensuring the long-term safety and stability of the tunnel. Specific implementation method 2:

[0187] This embodiment is a computer storage medium, in which a computer program is stored. The computer program is loaded and executed by a processor to implement the numerical prediction method for the dynamic response of a flexible pipe body of a real-scale floating tunnel under a vertical-inclined combined anchor mooring.

[0188] It should be understood that the storage medium described in this embodiment includes but is not limited to magnetic storage media and optical storage media; the magnetic storage media includes but is not limited to RAM, ROM, and other storage media such as hard disks and USB flash drives. Specific implementation method three:

[0190] This embodiment is a numerical prediction device for the dynamic response of a flexible pipe body of a real-scale floating tunnel under a vertical-inclined combined anchor cable mooring. The device includes a processor and a memory. A computer program is stored in the memory. The computer program is loaded and executed by the processor to implement a numerical prediction method for the dynamic response of a flexible pipe body of a real-scale floating tunnel under a vertical-inclined combined anchor cable mooring.

[0191] It should be understood that the device described in this embodiment includes but is not limited to a device including a processor and a memory, and may also include other devices corresponding to units or modules with information collection, information interaction, and control functions, for example, the device may also include a signal collection device, etc. The device includes but is not limited to a PC, a workstation, a mobile device, etc.

[0192] The present invention may also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A numerical prediction method for dynamic response of flexible pipe body of full-scale floating tunnel under vertical-inclined combined anchor cable mooring, characterized in that: include: Step 1: Establish a wave-current coupling excitation numerical environment model based on the VOF method and force wave elimination technology; Step 2: Mesh the suspended tunnel body and environment, including the following steps: Step 201, firstly create various component geometric components, including background watershed components, wave propagation area components, overlapping area components that can cover the motion range of the tube body, suspended tunnel tube body components, internal flow field area components and densification area components; Step 202, allocating the background watershed component, the overlapping area component, the suspended tunnel body component, and the internal flow field area component to four different areas; Step 203, expand the geometry and operate the nodes; then select the cutting volume mesh for the background flow domain, select the polyhedral mesh for the overlapping area, select the directional mesh for the floating tunnel body, and select the directional mesh for the internal flow field area; Step 204, first add a volume control for the background basin. In this process, select Create Volume Control and rename the new node as Wave, then input the wave propagation area component; then add an encrypted area grid, rename it as Encrypted and customize the size; Step 205, add volume control for the overlapping area. In this process, select New Volume Control, rename the new node to block, then input the block component, select the Cut Volume Mesher node and customize the size; Step 206, generate a directional mesh. In this process, select the directional mesh node, rename the generated node to tube body, and then enter the parts and customize the size; The same treatment is performed on the internal flow field area; Step 207, define overlapping grids; select the background watershed and the overlapping area at the same time, select Create Interface and then select Overlap Grid; Step 208, generating all grids; Step 3: Establish the CFD numerical analysis model of the floating tunnel flexible pipe body: The forces on the suspended tunnel body during operation include anchor cable tension, self-gravity and fluid force, and the fluid force includes wave force. The self-gravity of the suspended tunnel causes it to act downward, and the upward force generated by the buoyancy of the tunnel, the gravity of the tube body and the buoyancy together constitute the initial mechanical balance of the system. Under static water conditions, the anchor cable generates pre-tension by being tightened. The vibration response of the suspended tunnel pipe body is determined by the combined effects of fluid force, anchor cable tension, self-gravity and buoyancy. Wave force is used as an external excitation. The NS equation is solved by CFD method to calculate the wave pressure and shear force distribution on the pipe surface. Wave pressure and shear force excite vibration and cause displacement changes. The displacement change of the pipe body affects the tensile state of the anchor cable, which triggers the dynamic adjustment of the anchor cable tension. The change of anchor cable tension is the result of the vibration of the pipe body caused by wave force. At the same time, the anchor cable tension limits the amplitude of the pipe body vibration through the reaction force. Through the anchor cable-pipe coupling vibration equation, a dynamic connection is formed between the pipe body vibration and the anchor cable tension. The anchor cable tension is updated in real time according to the relative displacement and velocity change of the pipe body. The anchor cable tension, self-gravity, buoyancy and wave force maintain the dynamic balance of the suspended tunnel pipe body. In STAR-CCM+, based on the combined anchor cable suspended tunnel model, wave force causes pipe body vibration, and the anchor cable tension feeds back and adjusts the displacement and vibration of the pipe body in real time, while gravity and buoyancy participate in maintaining the mechanical balance of the system. The wave force, anchor cable tension and the displacement of the pipe body interact with each other in continuous iteration and update to form an integrated numerical model of the vibration response of the suspended tunnel. Finally, according to the flow field conditions of the wave-current coupling excitation numerical environment model set previously, the entire flow field is initialized, and the appropriate calculation step size is selected according to the calculation requirements to start the numerical simulation.

2. According to claim 1, a method for numerical prediction of dynamic response of a flexible pipe body of a full-scale floating tunnel under vertical-inclined combined anchor cable mooring, characterized in that: In the process of calculating the wave pressure and shear force distribution on the pipe surface, the wave pressure in, is the pressure exerted by the wave at position x and depth z, where x is the horizontal position, z is the coordinate perpendicular to the sea surface, and t is time; ρ is the fluid density, g is the acceleration due to gravity, A is the amplitude of the wave; h is the water depth; k is the wave number, and ω is the angular frequency of the wave.

3. The method for numerical prediction of dynamic response of flexible pipe body of full-scale floating tunnel under vertical-inclined combined anchor cable mooring according to claim 2 is characterized in that: The wave number k=2π / λ, where λ is the wavelength.

4. The method for numerical prediction of dynamic response of flexible pipe body of full-scale floating tunnel under vertical-inclined combined anchor cable mooring according to claim 1 is characterized in that: The anchor cable-tube coupling vibration equation is as follows: Where ρ is the density of the fluid; C L is the lift coefficient; v is the flow velocity; θ is the inclination angle of the anchor cable; ω v is the vortex discharge frequency; L is the length of the anchor cable; D t is the diameter of the anchor cable; is the sum of the mass of the anchor cable per unit length and the additional water mass; D n Symbols introduced for the convenience of calculation, y is the lateral displacement of the anchor cable, and They represent the lateral velocity and acceleration of the anchor cable respectively; n is the order; c is the viscous damping coefficient of the anchor cable; A1 is the cross-sectional area of ​​the anchor cable; E eq is the equivalent elastic modulus; Z is the vibration displacement of the tube body, and are the vibration velocity and acceleration respectively; ω1 is the natural frequency of the anchor cable; ω2 is the natural frequency of the pipe body; ξ2 is the damping ratio of the pipe body; M is the mass of the suspended tunnel.

5. A method for numerically predicting dynamic response of a flexible pipe body of a full-scale floating tunnel under vertical-inclined combined anchor mooring according to any one of claims 1 to 4, characterized in that: The construction process of the combined anchor cable suspended tunnel model includes: (1)Import file: Open the STAR CCM+ software and import the mesh file obtained in step 2; (2)Selection Physical Model: First, create a fluid physical continuum, namely physical continuum 1, and select the following models in order: three-dimensional, implicit unsteady, multiphase, multiphase interaction, fluid volume, turbulence model, SST K-Omega model, gradient, separated flow, multiphase equation of state, and check gravity, VOF wave, and adaptive time step in the optional models, and finally click OK; then create a solid physical continuum, namely physical continuum 2, select three-dimensional, implicit unsteady, solid, solid stress, Rayleigh damping, flexible DFBI motion, and gravity model, and finally click OK; (3)Define the flexibleDFBI movement: Click Tools > Motion Node, right-click the Motion Node, and then select New > DFBI Deformation. A new node named DFBI Deformation is added to the Motion Manager; ">" indicates the next step; (4)Edit 6-DOF volume parameters: Select Region > Overlap Region > Physical Value > Motion Assignment node, set the motion to DFBI deformation; then right-click the DFBI > 6-DOF Body node and select New Body > 3D > Continuum; rename the newly created node to Tube; then right-click Tube > Create Body Motion, create a new node named Tube-motion under the Motion node, and create a new solid displacement in the Tube-motion node for backup; (5)Model parameter setting: Select DFBI>6 DOF Body>Tube Body node with the mouse, add moving parts and suspension tunnel mass under this node; check the motion properties of X-axis movement, Z-axis movement and Y-axis rotation in the Free Motion node; customize the moment of inertia and center of mass of the suspension tunnel in the Initial Value node; (6)Define the motion of the SubmergedFloating Tunnel: Select the Region > Suspension Tunnel Body > Physical Conditions > Flexible DFBI Motion Options node, and set the Flexible DFBI Motion Options to DFBI-Partially deformable; in the Suspension Tunnel Body > Physical Values ​​> Motion Assignment node, set the motion to Body-motion-Solid Displacement; then in the Suspension Tunnel Solid > Segment node, set the two end faces to Fixed Constraints; (7)Define the internal flow field regional motion: Select Region > Internal Flow Region > Physical Values ​​> Motion Assignment node and set the motion to DFBI deformation; (8)Create interface: The surface where the outer wall of the tube body contacts the flow field and the surface where the inner wall of the tube body contacts the air flow field are respectively set as the phase contact interface; the operation method is similar to the method of creating an overlapping grid; (9)Add the anchor cable to the body coupling module: Right-click DFBI > Body Coupling node and add the required anchor cables, including spring-damper, catenary and other contact forms; (10)Solver setup: Click Solver > Implicit Unsteady State and set the required time step. Then click the 6 DOF Mesh Deformation node and check Zero Deformation, Recalculate Interfaces, Boundary Layer Deformation, and Keep Temporary Storage to meet the deformation requirements. (11)Stop criterion setting: Click the Stop Criteria node, uncheck the Displacement Criterion, Force Criterion, Maximum Steps, and Stop File functions, then set the number of iterations in the Maximum Inner Iterations node and the running time in the Maximum Physical Time node; (12)Initialize Solution andRun Calculation: First click the Initialize Solution button with the mouse, then click the Run button to start the simulation calculation.

6. The method for numerical prediction of dynamic response of flexible pipe body of full-scale floating tunnel under vertical-inclined combined anchor cable mooring according to claim 5 is characterized in that: The multiphase in step (2) is a gas-liquid two-phase flow.

7. The method for numerical prediction of dynamic response of flexible pipe body of full-scale floating tunnel under vertical-inclined combined anchor cable mooring according to claim 5 is characterized in that: In the step (2), in the process of selecting the fluid volume, wave loads are introduced, and flow is added on this basis to reflect the influence of wave and flow on the vibration of the pipe body; The wave loads are as follows: Horizontal speed of the wave: u(x,t)=Aωcosh(k(z+h))cos(kx-ωt) Among them, A is the amplitude of the wave; ω is the angular frequency of the wave; k is the number of waves; h is the water depth; z is the coordinate perpendicular to the sea surface; t is time; x is the horizontal position; Surface wave pressure: in, is the pressure exerted by the wave; g is the acceleration due to gravity; η is the deformation of the wave surface; is the rate of change of water surface over time; Wave pressure inside the fluid: in, is the pressure exerted by the wave at position x and depth z, where x is the horizontal position, z is the coordinate perpendicular to the sea surface, and t is time; ρ is the fluid density, g is the acceleration due to gravity, A is the amplitude of the wave; h is the water depth; k is the wave number, and ω is the angular frequency of the wave.

8. The method for numerical prediction of dynamic response of flexible pipe body of full-scale floating tunnel under vertical-inclined combined anchor cable mooring according to claim 5 is characterized in that: In the step (9), during the process of adding the required anchor cables, an anchor cable-tube coupling effect is introduced; the anchor cable-tube coupling effect is realized by an anchor cable-tube coupling vibration equation; The anchor cable-tube coupling vibration equation is as follows: Where ρ is the density of the fluid; C L is the lift coefficient; v is the flow velocity; θ is the inclination angle of the anchor cable; ω v is the vortex discharge frequency; L is the length of the anchor cable; D t is the diameter of the anchor cable; is the sum of the mass of the anchor cable per unit length and the additional water mass; D n Symbols introduced to facilitate calculations: C D =0.7 is the drag coefficient, z is the integral variable; y is the lateral displacement of the anchor cable, and They represent the lateral velocity and acceleration of the anchor cable respectively; n is the order; c is the viscous damping coefficient of the anchor cable; A1 is the cross-sectional area of ​​the anchor cable; E eq is the equivalent elastic modulus; Z is the vibration displacement of the tube body, and are the vibration velocity and acceleration respectively; ω1 is the natural frequency of the anchor cable; ω2 is the natural frequency of the pipe body; ξ2 is the damping ratio of the pipe body; M is the mass of the suspended tunnel.

9. A computer storage medium, wherein a computer program is stored in the storage medium, characterized in that: The computer program is loaded and executed by the processor to implement the numerical prediction method for dynamic response of a flexible pipe body of a real-scale floating tunnel under vertical-inclined combined anchor mooring as described in any one of claims 1 to 8.

10. A numerical prediction device for dynamic response of a flexible pipe body of a full-scale floating tunnel under vertical-inclined combined anchor cable mooring, the device comprising a processor and a memory, characterized in that: The memory stores a computer program, which is loaded and executed by the processor to implement the numerical prediction method for dynamic response of a flexible pipe body of a real-scale floating tunnel under vertical-inclined combined anchor mooring as described in any one of claims 1 to 8.

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