Method for constructing load dynamic response model of pile type fence structure

Abstract

The invention belongs to the field of ocean devices, and provides a pile type fence structure load dynamic response model construction method, which comprises the following steps: obtaining engineering arrangement parameters of a fence structure, constructing a wave flow field near the fence structure based on a potential flow theory, and calculating the speed and acceleration of a water quality point; piles and connecting components are regarded as rigid structures, a rigid body dynamic motion equation is established, a netting system is regarded as a flexible structure, and a dynamic model of the netting system is established through a concentrated mass point method; hydrodynamic loads of the piles, the netting and the connecting components are calculated, and effective tension of the slender rod components is calculated; calculating the horizontal bearing capacity of the pile foundation to simulate pile-soil interaction; and finally, carrying out numerical solution on the kinetic equation by adopting a semi-implicit Euler method to obtain dynamic response results of pile bending moment, netting tension and node displacement. The multi-system coupling dynamic response characteristic of the pile type fence structure under the wave action can be comprehensively reflected, and the method is suitable for safety evaluation and engineering design of the fence structure.

Description

Technical Field

[0001] This invention belongs to the field of marine equipment, and specifically relates to a method for constructing a load dynamic response model for a pile-type fence structure. Background Technology

[0002] With the continuous expansion of nearshore aquaculture, enclosure aquaculture, as an important marine aquaculture method, is widely used in the large-scale farming of fish and other aquatic economic animals. Enclosure aquaculture typically uses engineering facilities such as stakes, netting, ropes, and connecting components to create a relatively enclosed aquaculture body in nearshore waters, thereby achieving effective isolation and management of the farmed organisms. Based on different structural forms, existing enclosure aquaculture facilities can be mainly divided into two categories: floating rope enclosures and stake enclosures.

[0003] Among them, floating rope fences typically employ a structure combining flexible floats and netting. While their deployment is flexible and relatively unrestricted by sea conditions, their overall structural rigidity is low, making them prone to significant deformation or even structural failure under strong winds and waves, thus failing to meet the safety requirements of high-risk sea conditions. In contrast, pile-supported fences, by anchoring piles to the seabed, provide the fence structure with higher overall rigidity and bending resistance, exhibiting significant advantages in resisting ocean dynamics such as waves and currents. Therefore, they are more widely used in aquaculture projects with large-scale investments and high structural safety requirements.

[0004] However, as a relatively new form of marine engineering structure, pile-supported railings still lack systematic and mature technical support in engineering design theory. Existing research largely focuses on the hydrodynamic characteristics of the railing structure or its components under wave and current conditions. For example, it uses the lumped mass method to study the tension distribution and deformation characteristics of the mesh system, or analyzes the influence of wave parameters, mesh size, and the number of pile rows on local forces through numerical simulation and experiments. While these studies reveal the stress characteristics of the railing structure to some extent, they mostly remain at the level of analyzing single structural components or single physical processes, and have not yet formed a complete load-dynamic response model oriented towards engineering design requirements.

[0005] In existing technologies, hydrodynamic analysis of pile-and-column fence structures often employs static or quasi-static methods, or ignores the reaction effect of structural motion on hydrodynamic loads in numerical models. These methods are prone to load estimation errors when facing strongly nonlinear wave conditions or significant structural homing, making it difficult to provide a reliable basis for fence structure safety assessment and optimization. Especially when dealing with different pile arrangements, wave-crossing design schemes, and foundation conditions, existing technologies lack a unified modeling method that comprehensively considers wave-current fields, structural dynamic response, and pile-soil interactions. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a method for constructing a load dynamic response model for a pile-and-column fence structure. The pile-and-column fence structure includes a pile system, a mesh system, and connecting components; the method includes the following steps: Based on the engineering layout of the pile-and-column fence structure, obtain the structural parameters of the pile-and-column system, the wire mesh system, and the upper connecting components. By employing potential flow theory, the fluid near the fence is regarded as an ideal fluid that is irrotational, inviscid, and has velocity potential, and the velocity potential problem in the flow field is simplified to the Laplace equation with fluid boundary conditions. Treating the piles and connecting components as rigid structures, we establish rigid body motion equations using the principles of rigid body kinematics. Treating the mesh as a flexible structure, the loads acting on the elements are equivalently applied to concentrated mass points, and a differential equation of motion about the mass points is established. Calculation of hydrodynamic loads on piles, netting, and connecting components based on the improved Morison equation; The piles, netting, and connecting rods are all considered as linear elements of a hollow tube structure. The effective tension of the linear elements is calculated. The horizontal bearing capacity of the pile foundation is calculated using the Py curve method. The semi-implicit Euler method is used to solve the acceleration, velocity and displacement of the pile and the mesh node at a fixed time step. The position and orientation of the free body and the flexible node are updated by prediction-correction-iteration until the error of two consecutive iterations meets the convergence condition, and the dynamic response results of pile bending moment, mesh tension and node displacement are obtained.

[0007] Furthermore, the structural parameters include: The diameter of the pile, the length of the pile, the density of the pile material, and the elastic modulus of the pile material; The wire diameter, mesh size, density of the mesh material, and modulus of elasticity of the mesh; The spacing between adjacent piles, the hanging height of the mesh on the piles, and the arrangement of connecting components.

[0008] Furthermore, the Laplace equation with fluid boundary conditions is: , In the formula, , , , Let represent the first-order velocity potential, the first-order incident potential, the first-order radiation potential, and the first-order diffraction potential, respectively. , , These are spatial coordinates.

[0009] Furthermore, the equation of motion for the rigid body is: , In the formula, It is the inertial load of the system unit. It is the damping force of the system. It is the system stiffness load. t is the external load of the element, p, v and a are the element position, velocity and acceleration vectors respectively, and t is the simulation time.

[0010] Furthermore, the differential equation of motion for the mass point is: , In the formula, For the quality of concentrated quality points, Its acceleration, It is drag force. It is inertial force. It's the tension of the network cable. and These represent the buoyancy and gravity acting on the mass point, respectively.

[0011] Furthermore, the improved Morison equation is as follows: , in: Indicates fluid load; Indicates the drag coefficient; Indicates fluid density; Represents the projected area of ​​the structure along the flow velocity direction; Indicates the velocity of the structural unit; Indicates the acceleration of the structural unit; Indicates the velocity of water particles; Indicates the acceleration of water particles; Indicates the volume of water discharged; This represents the additional quality coefficient.

[0012] Furthermore, the drag coefficient is set to 1.4.

[0013] Furthermore, the additional quality coefficient is set to 2.0.

[0014] Furthermore, the effective tension of the line element is calculated as follows: , In the formula, It is the effective tension of the line unit. It is the tension of the outer wall of the pipeline. It's internal pressure. It is external pressure. It is the inner cross-sectional area of ​​the pipeline. It is the external cross-sectional area.

[0015] Furthermore, the outer wall tension The calculation formula is as follows: , In the formula, It is the elastic modulus of a linear element. It is the effective cross-sectional area. Let be the axial strain of the element. It is Poisson's ratio. , These are the inner and outer cross-sectional areas of the pipeline unit, respectively. It is the damping coefficient. It is the initial length of the line unit. This is the current length of the line unit. It is the iteration time.

[0016] The method for constructing a load-dynamic response model for pile-and-column fence structures provided by this invention enables comprehensive modeling and coupled analysis of the wave flow field, hydrodynamic load, structural dynamic response, and pile-soil interaction involved in the fence structure under wave action within a unified computational framework. This method obtains water particle velocity and acceleration information through potential flow theory and incorporates the influence of structural motion on hydrodynamic loads into the calculation process using an improved Morison equation. This avoids the problem in existing technologies where hydrodynamics is simplified to be determined solely by the external wave field while ignoring structural motion feedback. The resulting load calculations are more physically reasonable and can more realistically reflect the actual stress state of the pile-and-column fence structure in a wave environment. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 It is a physical diagram of the model test setup; Figure 2 This is a schematic diagram of the model test setup; Figure 3This is a comparison diagram between the measured wave force and the calculated wave force acting on the pile-net structure; Figure 4 This is a comparison between the test results and numerical results of piles under wave action. Detailed Implementation

[0019] To make the technical solution of the present invention clearer and more complete, the method for constructing the load dynamic response model of the pile-column fence structure of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0020] This embodiment takes the pile-post fence structure as the research object. The pile-post fence structure is a fixed enclosure structure set in near-shore waters. It is composed of a pile system, a netting system and connecting components.

[0021] The pile system includes several vertically set piles anchored in the seabed. As the main load-bearing component of the fence structure, the pile system is used to withstand the hydrodynamic loads transmitted by waves, currents and netting, and to provide the fence structure with horizontal and vertical bearing capacity and bending stiffness to ensure the overall stability of the fence structure under the design wave conditions.

[0022] The netting system is installed along the direction of the pile arrangement and connected to the pile system through connecting components. It is used to enclose and form an aquaculture water area. The netting system undergoes dynamic deformation under the action of waves and water flow, and bears the drag force and inertial force generated by the fluid. Its stress state directly affects the safety of the fence structure and the effective enclosure effect of the aquaculture water body.

[0023] The connecting component is installed between the pile system and the netting system to achieve mechanical connection and load transfer between the two. The connecting component can transfer the tensile force generated by the netting system under wave action to the pile system, so that the fence structure forms a unified force system.

[0024] In this embodiment, the pile-type fence structure can adopt a single-row pile arrangement or a double-row pile arrangement according to engineering requirements. Different numbers of pile rows are used to adapt to different sizes of aquaculture water areas and different levels of hydrodynamic environment. The sea area where the fence structure is located has certain water depth, wave conditions, and foundation conditions. The water depth, wave parameters, and foundation soil parameters can be derived from actual engineering survey data or design standard data, and serve as the basic input conditions for subsequent wave and current field construction, structural dynamics modeling, and numerical calculation.

[0025] When implementing the method of the present invention, the fence structure is first parametrically described according to the engineering layout of the pile-column fence structure, and the structural parameters of the pile system, the netting system and the upper connecting components are obtained as the basic input conditions for establishing the load dynamic response model.

[0026] Specifically, the structural parameters include parameter information related to the geometric features, material properties, and spatial arrangement of the pile system, the mesh system, and the connecting components.

[0027] For a pile system, the structural parameters include at least the diameter of the pile, the length of the pile, the density of the pile material, and the elastic modulus of the pile material. The pile diameter and length are used to determine the stress area and bending resistance of the pile under wave action, while the material density and elastic modulus are used to describe the inertial and stiffness characteristics of the pile.

[0028] For a mesh system, the structural parameters include at least the wire diameter, mesh size, density of the mesh material, and elastic modulus. The wire diameter and mesh size are used to characterize the geometric and permeability properties of the mesh, while the material density and elastic modulus are used to describe the dynamic response and deformation properties of the mesh under the action of waves and water flow.

[0029] In addition, parameters related to the overall layout of the fence are also obtained, including the spacing between adjacent posts, the hanging height of the netting on the posts, and the arrangement of connecting components. The post spacing is used to determine the spatial scale and overall stress distribution of the fence structure, the netting hanging height is used to determine the stress range of the netting in the water depth direction, and the arrangement of connecting components is used to determine the force transmission path between the netting system and the post system.

[0030] The aforementioned structural parameters serve as initial input conditions for subsequent wave flow field construction, hydrodynamic load calculation, pile and netting dynamic modeling, and numerical solution processes. They remain consistent throughout the entire load dynamic response calculation process to ensure the stability and consistency of the model calculation results.

[0031] In this embodiment, in order to simulate the fluid motion state around the fence structure under wave action and to provide water particle velocity and acceleration inputs for subsequent hydrodynamic load calculations, the wave flow field near the fence structure is constructed using three-dimensional potential flow theory.

[0032] The construction of the wave flow field is an important foundation for the load dynamic response model of the pile-and-column fence structure. Its role is to obtain the motion information of water particles around the fence structure by describing the propagation, diffraction and fluid response caused by wave propagation and structural motion near the fence structure, thereby providing the necessary flow field parameters for subsequent calculation of the hydrodynamic loads of the piles, netting and connecting components based on the Morison equation.

[0033] In this embodiment, it is assumed that the fluid near the marine structure is an ideal fluid that is irrotational, inviscid, and possesses potential. Therefore, fluid motion can be described by a velocity potential function. Under these assumptions, the velocity potential problem in the flow field can be simplified to the Laplace equation with corresponding fluid boundary conditions: , In the formula, , , , Let represent the first-order velocity potential, the first-order incident potential, the first-order radiation potential, and the first-order diffraction potential, respectively. , , These are spatial coordinates.

[0034] Preferably, the wave theory used in the calculation is based on the fifth-order Stokes wave theory to describe the wave propagation characteristics under regular wave conditions. The fifth-order Stokes wave theory can well reflect the nonlinear characteristics of waves under medium water depth conditions and is suitable for the engineering conditions of the sea area where the pile-and-column fence structure is located.

[0035] Through the above process of constructing the wave flow field, the velocity and acceleration fields of water particles at any location around the fence structure can be obtained, thus providing a basis for the calculation of hydrodynamic loads on subsequent piles, netting and connecting components, as well as the analysis of structural dynamic response.

[0036] In this embodiment, the piles and connecting components are considered as rigid structures, and their dynamic motion equations are established using the principles of rigid body kinematics.

[0037] In pile-and-column fence structures, the piles and connecting components are typically made of high-rigidity materials such as steel. Their structural dimensions are relatively large, and under design wave conditions, their elastic deformation is negligible compared to the overall displacement and rotational deformation. Treating the piles and connecting components as rigid bodies simplifies the dynamic modeling process while maintaining computational accuracy, thereby improving the overall model's computational efficiency and stability.

[0038] Under the above assumptions, the motion of the piles and connecting components can be described using the principles of rigid body kinematics. By establishing the corresponding dynamic equations, their displacement, velocity, and acceleration responses under external loads can be characterized.

[0039] The kinematic equations of a rigid body are as follows: , In the formula, It is the inertial load of the system unit. It is the damping force of the system. It is the system stiffness load. t is the external load of the element, p, v and a are the element position, velocity and acceleration vectors respectively, and t is the simulation time.

[0040] The dynamic equations of motion are used to reflect the overall motion characteristics of the piles and connecting components during wave action, rather than the minute deformations of local components.

[0041] In this embodiment, the external loads acting on the piles and connecting members mainly include hydrodynamic loads generated by waves and water flow, as well as tensile forces generated by the mesh system under wave action and transmitted to the pile system through the connecting members. By incorporating the above-mentioned external loads into the rigid body dynamics equations, the mechanical coupling between the pile system, connecting members, and mesh system can be achieved, thereby accurately describing the overall dynamic response behavior of the fence structure in a wave environment.

[0042] By employing a rigid body dynamics model to model the piles and connecting components, it can be integrated with the flexible dynamics model of the mesh system in subsequent numerical solutions, enabling a unified analysis of the overall dynamic response of the pile-and-column fence structure under wave action.

[0043] In this embodiment, the mesh system is regarded as a flexible structure, and its dynamic model is established using the lumped mass point method.

[0044] Netting is typically made of flexible materials with relatively small geometric dimensions, resulting in significant dynamic deformation and tension changes under the influence of waves and water flow. Treating netting as a rigid structure would fail to adequately reflect its deformation characteristics under wave action and its impact on the overall stress state of the fence. Therefore, a flexible dynamic model is needed to describe the netting system.

[0045] In this embodiment, the lumped mass point method is used to discretize the mesh system. Specifically, the mesh is discretized along its geometry into several linear elements, with the mass of each linear element concentrated at corresponding mass point positions. Adjacent mass points are connected by massless springs to simulate the axial tensile characteristics of the mesh wires. Through this discretization method, the dynamic behavior of the continuous flexible structure can be transformed into a dynamic problem of a set of mass points without significantly increasing computational complexity, resulting in the following differential equations of motion for the mass points: , In the formula, For the quality of concentrated quality points, Its acceleration, It is drag force. It is inertial force. It's the tension of the network cable. and These represent the buoyancy and gravity acting on the mass point, respectively.

[0046] During wave action, the netting element is subjected to the combined effects of hydrodynamic loads, gravity, buoyancy, and tension from adjacent elements. The hydrodynamic loads acting on each element are equivalently distributed and applied to the corresponding mass points, thereby establishing the differential equation of motion for each mass point to describe its motion response under wave action.

[0047] The differential equation of motion for the mass point is used to characterize the changes in displacement, velocity, and acceleration of the mass point under the action of external forces. The external force term includes the hydrodynamic load calculated by the subsequently improved Morison equation and the tension generated by adjacent line elements. By numerically solving the above differential equation of motion, the tension distribution and deformation state at various locations of the mesh can be obtained.

[0048] By employing the lumped mass point method to model the mesh system, the dynamic tension changes and deformation characteristics of the mesh under wave action can be effectively described. Furthermore, the mechanical coupling between the mesh system and the rigid body dynamics model of the piles and connecting components can be achieved, thus reflecting the overall dynamic response behavior of the pile-and-column fence structure within a unified computational framework.

[0049] In this embodiment, for the components in the piles, netting, and connecting members that satisfy the slender rod assumption, under the condition that the diameter of the fence structure is relatively small relative to the wavelength, the fluid force is decomposed into two parts: drag and inertia, to obtain the instantaneous hydrodynamic load acting on the structural unit. This load is then input as an external force into the rigid body dynamics model of the piles and the concentrated mass point dynamics model of the netting, thereby achieving the coupling of wave flow field and structural dynamic response calculation. The improved Morison equation is used in the calculation process.

[0050] For typical slender cylinders or rods, when the member is fixed or its own motion is neglected (i.e., the member's velocity and acceleration are negligible), the Morison equation is usually written as a superposition of drag and inertia terms: , The first term in the addition is the drag force term, which describes the drag effect caused by viscous drag and vortex shedding; the second term in the addition is the inertial force term, which describes the effect of unsteady fluid acceleration on the component (including the additional mass effect), and its core input is the acceleration of water particles. However, the aforementioned original form implicitly assumes that the motion of the component relative to the water body has little impact, or can be approximated as the component being stationary. For the netting and connecting components in this embodiment, especially when there is significant follow-up displacement and acceleration under wave action, directly adopting this original form will lead to an estimation error in the hydrodynamic load.

[0051] However, in the fence structure of this embodiment, the netting is a flexible structure, which has significant follow-up velocity and acceleration under the action of waves. Although the piles and connecting components are modeled as rigid bodies, they also have overall motion (displacement, velocity, acceleration) in the dynamic response calculation.

[0052] If the original Morison equation with the components stationary is still used, the drag term is determined only by the velocity of the water particles and the inertial term is determined only by the acceleration of the water particles, which cannot reflect the influence of structural motion on relative flow velocity and relative acceleration.

[0053] Therefore, in order to enable the hydrodynamic load to reflect the relative motion between the water body and the component, and to include the additional mass reaction force caused by the component's own acceleration in the inertial term, an improved form is required.

[0054] The improved Morison equation expression in this embodiment is as follows: , in: This indicates fluid load (hydrodynamic load acting on a structural unit). This represents the drag coefficient (preferably 1.4). Indicates fluid density; Represents the projected area of ​​the structure along the flow velocity direction; Indicates the velocity of the structural unit; Indicates the acceleration of the structural unit; Indicates the velocity of water particles; Indicates the acceleration of water particles; Indicates the volume of water discharged; This represents the additional quality coefficient (preferably, a value of 2.0). The core principle of the improvement lies in: The drag term is changed from the velocity of water particles to relative velocity, that is, using... Alternative This allows the drag force to change with the structure's kinetic velocity, reflecting the dependence of viscous drag on relative flow velocity.

[0055] The inertial term retains the water particle acceleration driving term while introducing a structural acceleration correction term, in which... This indicates the inertial effect of fluid acceleration on a component (including the added mass effect). It is used to characterize the additional mass reaction force correction caused by the component's own acceleration, so that the inertial term can still maintain physical consistency when the component moves.

[0056] The above improvements enable the hydrodynamic load to be determined not only by the external wave flow field, but also to change in real time with the dynamic response of the components, thus making it applicable to the coupled dynamic calculation of fence structures.

[0057] After adopting the improved Morison equation, the corresponding instantaneous hydrodynamic load can be calculated at each time step for each pile element, wire mesh element, and connecting member element. .

[0058] The hydrodynamic load was then input as an external force term: The rigid body motion equations of the pile and connecting components are used to solve for the bending moment of the pile and the overall motion response. The differential equations of motion of the concentrated mass point of the mesh are used to solve for the displacement of the mesh nodes and the tension distribution of the mesh.

[0059] The improved Morison equation can reflect the feedback relationship between structural motion and hydrodynamic loads in the dynamic response solution process, avoiding the simplification of hydrodynamics to static loads driven only by external wave fields. For flexible components with significant follow-up motion, such as netting, it can more reasonably characterize the transient force and tension changes under wave action. It ensures that the obtained dynamic response results, such as pile bending moment, netting tension, and nodal displacement, are consistent with the physical process considering the influence of structural motion, thereby improving the applicability of the model and the consistency of calculation.

[0060] In this embodiment, the piles, netting, and thin rods in the connecting components are uniformly regarded as linear units of the hollow tube structure, and their stress state is described based on this.

[0061] The piles, wire mesh, and connecting components all meet the characteristics of slender members in terms of geometry. Their cross-sectional dimensions are relatively small compared to the length of the member, and the stress distribution differences within the cross-section can be ignored. Therefore, their mechanical behavior can be equivalent to the force problem of line elements transmitted along the member's axis. Through the above equivalent treatment, the force analysis process of the member can be significantly simplified while ensuring the accuracy of engineering calculations, and it is convenient to couple them with the lumped mass point model and rigid body dynamics model.

[0062] During wave action, the linear unit not only bears the external wall tension generated by the material's own stretching, but also experiences the combined effects of internal fluid pressure and external water pressure. For a hollow tube-structured linear unit, its axial stress state depends not only on the tensile deformation of the component material, but also on the additional axial force caused by the internal and external pressure difference.

[0063] Specifically, slender members, including piles and wires, are all considered as linear units of a hollow tubular structure, and the effective unit tension is calculated using the following formula: , In the formula, It is the effective tension of the line unit. It is the tension of the outer wall of the pipeline. It's internal pressure. It is external pressure. It is the inner cross-sectional area of ​​the pipeline. It is the external cross-sectional area.

[0064] outer wall tension The calculation formula is as follows: , In the formula, It is the elastic modulus of a linear element. It is the effective cross-sectional area. Let be the axial strain of the element. It is Poisson's ratio. , These are the inner and outer cross-sectional areas of the pipeline unit, respectively. It is the damping coefficient. It is the initial length of the line unit. This is the current length of the line unit. It is the iteration time.

[0065] In this embodiment, by comprehensively considering the relationship between the outer wall tension of the wire element and the internal and external pressures, the concept of effective tension is introduced to characterize the actual stress state of the wire element under wave action. The effective tension is used to uniformly reflect the combined influence of material tensile and compressive effects on the axial force of the wire element, thereby avoiding deviations caused by describing the component's stress solely with material tensile force.

[0066] By calculating the effective tension of the wire element, the tension variation law of the wire mesh under wave action can be accurately described. This effective tension can be introduced as an internal force term into the dynamic model of the concentrated mass point of the wire mesh and the dynamic analysis of the pile and connecting components, thereby realizing the unified calculation of hydrodynamic load, structural motion response and component internal force.

[0067] The above-mentioned effective tension calculation method based on hollow pipeline units enables piles, netting, and connecting components to have a consistent stress description under the same modeling framework, which is beneficial to improving the physical consistency and computational stability of the overall load dynamic response model.

[0068] In this embodiment, in order to reasonably reflect the interaction characteristics between the pile-column type fence structure and the foundation under the action of waves, the p-y curve method is used to calculate the horizontal bearing capacity of the pile foundation, and the pile foundation reaction force obtained therefrom is introduced into the pile-column dynamic model.

[0069] In the pile-column type fence structure, the lower part of the pile column is usually embedded in the seabed soil. Under the combined action of waves and netting tension, the pile column will produce horizontal displacement and rotational response, and the response will cause the soil on the side of the pile to generate a reverse acting force on the pile column. If the constraint effect of the foundation on the pile column is ignored in the dynamic response model, the displacement, bending moment and stress state of the pile column will be significantly amplified, and the stress behavior of the fence structure under actual engineering conditions cannot be truly reflected. Therefore, it is necessary to introduce pile-soil interaction into the dynamic model to improve the physical rationality of the model.

[0070] In this embodiment, the p-y curve method is used to describe the pile-soil interaction. The p-y curve method characterizes the lateral reaction force characteristics of the soil on the pile column at different displacement levels by establishing a non-linear relationship curve between the soil resistance p per unit length on the side of the pile and the displacement y on the side of the pile. This method can reflect the whole process of the soil developing from the elastic stage to the ultimate bearing state according to the physical and mechanical parameters of the foundation soil, and is applicable to the horizontal force analysis of the pile foundation under the action of waves.

[0071] Preferably, the p-y curve under the condition of soft clay in the "Code for Design of Pile Foundations in Water Transportation Engineering" 2022 is adopted, and the curve can be determined according to the following formula: When Y / Y50 < 8: , , When Y / Y50 ≥ 8: , In the formula, Y is the lateral horizontal deformation of the pile at a depth of Z below the mud surface, Y 50 is the lateral horizontal deformation of the pile corresponding to half of the ultimate horizontal soil resistance of the soil around the pile, ρ' is the correlation coefficient (preferably, take 2.5), ε 50 is the strain value at half of the maximum principal stress in the triaxial test, and d is the pile diameter. P is the standard value of the horizontal soil resistance per unit area acting on the pile at a depth of Z below the mud surface, and Pu is the standard value of the ultimate horizontal soil resistance per unit area on the side of the pile at a depth of Z below the mud surface, which is calculated according to the following formula.

[0072] When Z < Zr: , When Z ≥ Zr: , , In the formula, Cu is the standard value of the undrained shear strength of the undisturbed clay, γ is the unit weight of the soil, the ξ coefficient generally takes 0.25 - 0.50, and Zr is the depth of the turning point of the ultimate horizontal soil resistance.

[0073] In the specific calculation process, based on the type of foundation soil and its physical and mechanical parameters, a corresponding Py curve is constructed, and the soil resistance along the pile depth is calculated. By solving for the lateral displacement of the pile at each depth, the corresponding soil reaction force can be obtained, and this reaction force is applied as a distributed constraint force to the pile dynamic model.

[0074] By employing the above-described processing method, the combined effects of wave loads, mesh tension, and soil reaction can be simultaneously considered during the pile dynamics analysis, thereby achieving dynamic simulation of the interaction between the pile and the foundation. This method enables the displacement response and bending moment distribution of the pile to reflect the influence of foundation constraints on the overall dynamic behavior of the structure, which is beneficial for improving the engineering applicability and computational reliability of the load dynamic response model for pile-type fence structures.

[0075] In this embodiment, since the dynamic response process of the pile-column fence structure under wave action involves the coupling of multiple factors such as wave flow field, hydrodynamic load, structural motion and pile-soil interaction, the corresponding dynamic control equation is a set of nonlinear differential equations that vary with time, and it is difficult to obtain analytical solutions. Therefore, numerical methods are used to solve the dynamic equations.

[0076] Specifically, in this embodiment, a semi-implicit Euler method is used to calculate the dynamic equations of the pile and mesh node by step-by-step integration under a fixed time step. The semi-implicit Euler method can ensure numerical stability while maintaining computational efficiency during the calculation process, and is suitable for dynamic response problems involving the coupling of rigid and flexible bodies.

[0077] In the specific calculation process, firstly, based on the state variables of the previous time step, the displacement, velocity, and other state variables of the pile and the mesh node are predicted in the current time step. Then, based on the prediction results, the hydrodynamic load, the effective tension of the line element, and the pile foundation reaction are recalculated, and the updated external forces are substituted into the dynamic equation to correct the motion state of the pile and the mesh node. Through repeated iterations of the above prediction and correction process, the position, velocity, and direction of the free body and the flexible node are gradually updated.

[0078] Within each time step, the difference between two consecutive iterations is compared. When the difference is less than a preset convergence threshold, the numerical solution for the current time step is considered to have converged, and the calculation proceeds to the next time step. This method ensures good stability and consistency in the numerical solution process under nonlinear loads and structural follower conditions.

[0079] In the specific calculation process, based on the numerical calculation program executed by the computer, the displacement, velocity and other state variables of the pile and the mesh node are first predicted according to the state variables stored in the previous time step within the current time step. Subsequently, the computer recalculates the hydrodynamic load, effective tension of the line element and pile foundation reaction force based on the predicted state variables, and substitutes the updated external forces into the dynamic equation to correct the motion state of the pile and the mesh node. Through repeated iterative calculations in the computer during the above prediction and correction process, the position, velocity and direction of the free body and the flexible node are gradually updated.

[0080] Within each time step, the computer compares the difference between two consecutive iterations. When the difference is less than a preset convergence threshold, it determines that the numerical solution in the current time step has reached convergence and automatically proceeds to the next time step. This computer-implemented numerical solution method ensures good stability and consistency throughout the entire numerical solution process under nonlinear loads and structural follower conditions, thereby obtaining reliable dynamic response calculation results.

[0081] Through the numerical solution process of the semi-implicit Euler method described above, the displacement, velocity, and acceleration time history data of the piles under wave action can be obtained, and the bending moment distribution of the piles along the burial depth direction can be further calculated. Simultaneously, the displacement changes of the mesh nodes and the tension distribution of the line elements can also be obtained. These calculation results are used to characterize the overall load dynamic response characteristics of the pile-type fence structure under wave action and serve as the basis for subsequent structural safety analysis and engineering design evaluation.

[0082] Model validation was performed using physical experimental data from a pile-and-column fence. This experiment was conducted in a wave flume at the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The flume was 69m long, 2.0m wide, and had an effective water depth of 1.8m. The still water depth used in the experiment was 0.55m. To study the characteristics of wave action on the fence structure, a physical model was reconstructed at a 1:20 gravity similarity scale at a distance of 28m from the wave generator. Figure 1 The model piles are made of Q235 steel, 0.875m high and 0.025m in diameter. A force sensor is installed at the top of the central pile to collect the wave force acting on the pile network system. The sensor has a range of 10N and an accuracy of 0.005N. Detailed test setup is as follows: Figure 2 As shown. The netting material used in the experiment was polyethylene. The model was made of the same material as the prototype netting by using the gravity similarity criterion of variable-scale netting to ensure that the water flow resistance experienced by the model netting was consistent with that of the prototype netting.

[0083] To compare with the experimental results, the structural conditions in the numerical simulation were completely consistent with those in the experiment. Simultaneously, experimental results under two sets of characteristic wave conditions were selected for verification (one set of conventional wave conditions and one set of large wave conditions). Detailed model parameters are listed in Table 1 below. Figure 3 The comparison between the experimental results and numerical calculation results of the intermediate piles shows that the numerical model can accurately calculate and reconstruct the load change process of the fence piles under the action of wave cycles.

[0084] Table 1 Model Test Parameters

[0085] Figure 4 Comparisons between experimental and numerical results of the peak stress on the intermediate pile under two sets of wave conditions are presented. Here, the dimensionless parameter kR is used to represent the wave period, where k is the wave number and R is the pile radius. The wave number k and the period T satisfy a linear dispersion relation. , F / ρgAR 2 Let F be the dimensionless wave force, A be the wave amplitude, and F be the wave force acting on the structure. It can be seen that, regardless of whether it is a single pile or a pile-net combined load, the numerical calculation results agree well with the experimental values, with a maximum error within 5%. This indicates that the numerical method can effectively calculate the wave force and the lateral tension of the netting on both sides caused by the wave action.

[0086] The prior art mentioned in the foregoing background and specific embodiments sections can be considered as part of this invention and used to understand the meaning of some technical features or parameters.

Claims

1. A method for constructing a load dynamic response model for a pile-column fence structure, characterized in that, The post-type fence structure includes a post system, a wire mesh system, and connecting components; the method includes the following steps: Based on the engineering layout of the pile-and-column fence structure, obtain the structural parameters of the pile-and-column system, the wire mesh system, and the upper connecting components. By employing potential flow theory, the fluid near the fence is regarded as an ideal fluid that is irrotational, inviscid, and has velocity potential, and the velocity potential problem in the flow field is simplified to the Laplace equation with fluid boundary conditions. Treating the piles and connecting components as rigid structures, we establish rigid body motion equations using the principles of rigid body kinematics. Treating the mesh as a flexible structure, the loads acting on the elements are equivalently applied to concentrated mass points, and a differential equation of motion about the mass points is established. Calculation of hydrodynamic loads on piles, netting, and connecting components based on the improved Morison equation; The piles, netting, and connecting rods are all considered as linear elements of a hollow tube structure. The effective tension of the linear elements is calculated. The horizontal bearing capacity of the pile foundation is calculated using the Py curve method. The semi-implicit Euler method is used to solve the acceleration, velocity and displacement of the pile and the mesh node at a fixed time step. The position and orientation of the free body and the flexible node are updated by prediction-correction-iteration until the error of two consecutive iterations meets the convergence condition, and the dynamic response results of pile bending moment, mesh tension and node displacement are obtained.

2. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 1, characterized in that, The structural parameters include: The diameter of the pile, the length of the pile, the density of the pile material, and the elastic modulus of the pile material; The wire diameter, mesh size, density of the mesh material, and modulus of elasticity of the mesh; The spacing between adjacent piles, the hanging height of the mesh on the piles, and the arrangement of connecting components.

3. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 1, characterized in that, The Laplace equation with fluid boundary conditions is: ， In the formula, , , , Let represent the first-order velocity potential, the first-order incident potential, the first-order radiation potential, and the first-order diffraction potential, respectively. , , These are spatial coordinates.

4. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 1, characterized in that, The equation of motion for the rigid body is: ， In the formula, It is the inertial load of the system unit. It is the damping force of the system. It is the system stiffness load. t is the external load of the element, p, v and a are the element position, velocity and acceleration vectors respectively, and t is the simulation time.

5. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 1, characterized in that, The differential equation of motion for the mass point is: ， In the formula, For the quality of concentrated quality points, Its acceleration, It is drag force. It is inertial force. It's the tension of the network cable. and These represent the buoyancy and gravity acting on the mass point, respectively.

6. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 1, characterized in that, The improved Morison equation is as follows: ， in: Indicates fluid load; Indicates the drag coefficient; Indicates fluid density; Represents the projected area of ​​the structure along the flow velocity direction; Indicates the velocity of the structural unit; Indicates the acceleration of the structural unit; Indicates the velocity of water particles; Indicates the acceleration of water particles; Indicates the volume of water discharged; This represents the additional quality coefficient.

7. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 6, characterized in that, The drag coefficient is set to 1.

4.

8. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 6, characterized in that, The additional quality factor is set to 2.

0.

9. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 1, characterized in that, The effective tension of the line element is calculated as follows: ， In the formula, It is the effective tension of the line unit. It is the tension of the outer wall of the pipeline. It's internal pressure. It is external pressure. It is the inner cross-sectional area of ​​the pipeline. It is the external cross-sectional area.

10. The method for constructing a load dynamic response model for a pile-column fence structure according to claim 9, characterized in that, outer wall tension The calculation formula is as follows: ， In the formula, It is the elastic modulus of a linear element. It is the effective cross-sectional area. Let be the axial strain of the element. It is Poisson's ratio. , These are the inner and outer cross-sectional areas of the pipeline unit, respectively. It is the damping coefficient. It is the initial length of the line unit. This is the current length of the line unit. It is the iteration time.

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