A method and system for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine under the coupled action of scour and earthquake

Abstract

The application discloses a kind of four-pile jacket offshore wind turbine dynamic response simulation calculation method and system considering scour and earthquake coupling effect, applied to marine engineering and wind power engineering technical field, including: establishing the pile-soil-jacket wind turbine structure coupling finite element model including parameterized local scour pit, and based on the seismic response spectrum value at the natural vibration frequency of model unscoured state and site hydrogeological condition respectively determine control earthquake and a series of analysis working conditions of scour depth increment;Control earthquake is respectively input to the pile-soil-jacket wind turbine structure coupling finite element model under each scour depth analysis working condition, and the nonlinear dynamic time-history analysis under each control earthquake and scour depth combination working condition is carried out;The overall dynamic response of structure under different scour depths and the distribution of internal force and displacement in pile body are compared to carry out coupling effect evaluation.The application realizes accurately and efficiently to measure and calculate four-pile jacket offshore wind turbine dynamic response under the coupling effect of scour and earthquake.

Description

Technical Field

[0001] This invention relates to the fields of marine engineering and wind power engineering technology, and more specifically to a method and system for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic forces. Background Technology

[0002] Offshore wind power is an important direction for the development of clean energy. As development waters move towards deeper waters (20-50 meters), four-pile jacket foundations have become one of the mainstream foundation types due to their excellent overturning stability, high stiffness, and good environmental adaptability. However, in offshore wind farms located in seismically active zones, their foundations face the coupled effects of multiple environmental loads, including wind, waves, currents, and earthquakes. Long-term ocean currents and waves can cause the soil around the piles to be eroded, forming "scour pits," significantly weakening the lateral constraint of the soil on the piles and altering the dynamic characteristics of the structure. Seismic loads can trigger strong inertial forces and dynamic responses in the soil.

[0003] Currently, the design and research of offshore wind turbine foundations have the following limitations: Simplified load consideration: Most studies analyze scour and earthquake as independent factors, neglecting the nonlinear amplification effect that may result from their coupling. The weakening of soil support caused by scour can significantly alter the dynamic characteristics of a structure (such as its natural frequency), thereby affecting its response mode and vibration amplitude under seismic loading. Simple load superposition methods cannot accurately reflect this complex interaction.

[0004] Oversimplification of models: In numerical analysis, pile-soil interaction of the structure is often not considered, or linear elastic and oversimplified soil constitutive models are used, which cannot realistically simulate pile-soil interaction and key nonlinear behavior of soft clay under seismic cyclic loading, resulting in distorted analysis results.

[0005] Insufficient design evidence: Traditional design methods lack a systematic identification of the "most unfavorable load combination." For seismic loads, there is a lack of clear and quantifiable methods for selecting the most dangerous control ground motion for a specific structure from numerous seismic records; for scour, there is a lack of clear and quantifiable methods for quantitatively assessing the amplification of seismic response at different scour depths. This leads to designs that are either overly conservative, increasing costs, or contain safety hazards.

[0006] Therefore, how to provide a method that can accurately simulate the coupling mechanism of earthquake and scour, and based on this, perform systematic and refined dynamic response calculations, so as to provide a scientific and reliable theoretical basis for the seismic and scour-resistant design of jacket foundations for offshore wind turbines, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a method and system for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic forces. The aim is to establish a complete technical process from refined modeling, identification of the most unfavorable load, coupled nonlinear analysis to quantitative effect assessment, in order to accurately reveal the dynamic behavior of the structure under the combined effects of scour and seismic forces, and provide direct and quantitative data support for the optimized design and safety assessment of the structure.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic forces includes: Step 1: Establish a coupled finite element model of the pile-soil-jacket wind turbine structure containing parameterized local scour pits, and determine the control ground motion and a series of analysis conditions with increasing scour depth based on the seismic response spectrum at the natural frequency of the model in the unscoured state and the hydrogeological conditions of the site. Step 2: Input the control ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition, and perform nonlinear dynamic time history analysis under each combination of control ground motion and scour depth. Step 3: Compare the overall dynamic response of the structure and the distribution of internal forces and displacements in the pile body under different scour depths to assess the coupling effect of earthquake and scour.

[0009] Optionally, in step 1, the coupled finite element model of the pile-soil-jacket wind turbine structure includes the superstructure of the offshore wind turbine, the jacket support structure, the pile foundation, the surrounding soil domain, and the local scour pit; wherein, the superstructure of the offshore wind turbine includes: the wind turbine tower, the nacelle, and the rotor. The wind turbine tower and jacket support structure are simulated using spatial beam elements; The total mass of the nacelle and rotor is simplified and simulated using the lumped mass method. The pile foundation and surrounding soil domain are simulated using solid elements; The surrounding soil domain was simulated using an elastoplastic constitutive model, and the soil parameters were determined based on the variation of the undrained shear strength of the soil with depth. The geometry of the local scour pit is an inverted cone shape with a preset slope, and the scour depth is a variable parameter.

[0010] Optionally, the wind turbine tower constructed using spatial beam elements can be segmented, with each segment assigned different cross-sectional properties.

[0011] Optionally, the total mass of the nacelle and rotor is simplified using the lumped mass method, specifically: The total mass of the rotor-nacelle assembly is concentrated at the top of the tower. The horizontal offset distance of the rotor's center of mass relative to the nacelle's center of mass is set. The moment of inertia of the rotor about the three coordinate axes is calculated according to the following formula, and the moment of inertia is set at the concentrated mass point of the rotor-nacelle assembly.

[0012] in, , , These are the moments of inertia along the three coordinate axes, respectively. , These refer to the mass and length of the wind turbine blades, respectively. This is the horizontal offset distance of the rotor's center of mass relative to the nacelle's center of mass.

[0013] Optionally, in step 1, the process of establishing the coupled finite element model of the pile-soil-jacket wind turbine structure, which includes parameterized local scour pits, also includes: performing wind turbine frequency tuning design, specifically: By adjusting the cross-sectional stiffness properties of the jacket and pile body, the basic natural frequency of the structure under controlled scour conditions is kept far away from the operating frequency range of the rotor rotation frequency and blade passage frequency during wind turbine operation.

[0014] Optionally, in step 1, based on the seismic response spectrum at the natural frequency of the model in its unscourized state and the hydrogeological conditions of the site, the controlling ground motion and a series of analysis conditions with increasing scour depth are determined, specifically: The model calculates the fundamental natural frequency under scour-free conditions and selects multiple seismic ground motion records with significant seismic response spectrum values ​​at the fundamental natural frequency from the seismic ground motion database as control ground motions. Among them, the seismic records are acceleration time history data of different seismic events. Based on the acceleration time history data, the acceleration seismic response spectrum value at the fundamental natural frequency can be calculated. The control ground motion is determined by auxiliary analysis based on the acceleration seismic response spectrum value, combined with Fourier time history data and earthquake duration. Based on the hydrogeological conditions of the site, the maximum potential equilibrium scour depth is predicted, and a series of analytical conditions with increasing scour depth are set with the maximum equilibrium scour depth as the upper limit.

[0015] Optionally, in step 2, before inputting the control ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure for each scour depth analysis condition, and performing nonlinear dynamic time history analysis for each combination of control ground motion and scour depth, the following is also included: For each scour depth analysis case, a static general analysis is performed on the coupled finite element model of the pile-soil-jacket wind turbine structure. An iterative calculation method is used, and the result database file output after the previous geostress analysis step is imported into the predefined field of the subsequent static general analysis step. The displacement field and reaction force of the model after equilibrium are checked to see if they are close to zero. The stable initial state is imported as the initial state for nonlinear dynamic time history analysis.

[0016] Optionally, in step 2, the nonlinear dynamic time history includes: displacement time history, acceleration time history, pile bending moment, shear force, axial force distribution time history, and stress time history of key nodes of the jacket structure.

[0017] Optionally, in step 3, the overall dynamic response includes: the fundamental frequency change of the structure, the peak displacement and acceleration at the top of the tower, and the overall tilt angle; the distribution of internal forces and displacements in the pile body includes: the peak bending moment and location distributed along the pile body, the peak lateral displacement and location, and the distribution of pile body rotation angle; the assessment of the coupling effect of earthquake and scour includes: identifying the response parameters most sensitive to scour depth and determining the pile depth region where the scour amplification effect is most significant.

[0018] This invention also provides a simulation system for the dynamic response of a four-pile jacket offshore wind turbine under the coupled effects of scour and seismic forces, utilizing a method for simulating the dynamic response of the turbine under the coupled effects of scour and seismic forces. The system includes: Model building and control load condition determination module: used to establish a coupled finite element model of the pile-soil-jacket wind turbine structure containing parameterized local scour pits, and determine the control ground motion and a series of analysis conditions with increasing scour depth based on the seismic response spectrum value at the natural frequency of the model in the unscour state and the hydrogeological conditions of the site. Nonlinear dynamic time history analysis module: This module is used to input the control ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition, and to perform nonlinear dynamic time history analysis under each combination of control ground motion and scour depth. The earthquake and scour coupling effect assessment module is used to compare the overall dynamic response of the structure and the distribution of internal forces and displacements in the pile body under different scour depths in order to assess the coupling effect of earthquake and scour.

[0019] As can be seen from the above technical solution, compared with the prior art, this invention discloses a method and system for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupling effects of scour and seismic forces. This invention establishes a three-dimensional finite element model of the pile-soil-jacket wind turbine structure with parameterized local scour pits and conducts frequency tuning design. It scientifically selects control ground motion and sets the working condition of increasing scour depth. After iterative calculation to achieve stress balance in the model, it uses ABAQUS to conduct nonlinear dynamic time-history analysis of scour-seismic coupling, systematically extracts indicators, quantitatively evaluates the coupling effect, and constructs an integrated simulation and calculation system. This effectively solves the problems of oversimplification and singular load consideration in traditional research models, accurately captures the nonlinear amplification effect of the coupling, reveals the structural dynamic response law under coupling, and achieves accurate and efficient calculation of the dynamic response of a four-pile jacket offshore wind turbine under coupling. This provides quantitative scientific data and standardized technical solutions for the seismic and scour-resistant optimization design and safety assessment of this type of wind turbine foundation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the method flow provided by the present invention.

[0022] Figure 2 This is a schematic diagram of a coupled finite element model of a pile-soil-jacket wind turbine structure containing parameterized local scour pits, provided by the present invention.

[0023] Figure 3 This is a schematic diagram of the parameterized local scour pit provided by the present invention.

[0024] Figure 4 This is a schematic diagram of the seismic wave response spectrum provided by the present invention.

[0025] Figure 5 This is a schematic diagram of the geostress balance results provided by the present invention.

[0026] Figure 6 This is a schematic diagram of the lateral displacement cloud in the four-pile jacket foundation provided by the present invention.

[0027] Figure 7 A schematic diagram of vertical displacement cloud in a four-pile jacket foundation provided by the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: Embodiment 1 of this invention discloses a method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic forces, such as... Figure 1 As shown, it includes: Step 1: Establish a coupled finite element model of the pile-soil-jacket wind turbine structure, including parameterized local scour pits, such as... Figure 2 As shown, based on the seismic response spectrum at the natural frequency of the unscoured state of the model and the hydrogeological conditions of the site, the control ground motion and a series of analysis conditions with increasing scour depth were determined respectively.

[0030] The coupled finite element model of the pile-soil-jacket wind turbine structure includes the superstructure of the offshore wind turbine, the jacket support structure, the pile foundation, the surrounding soil domain, and local scour pits; among which, the superstructure of the offshore wind turbine includes: the wind turbine tower, the nacelle, and the rotor. The wind turbine tower and jacket support structure are simulated using spatial beam elements; The total mass of the nacelle and rotor is simplified and simulated using the lumped mass method. The pile foundation and surrounding soil domain are simulated using solid elements; The surrounding soil domain was simulated using an elastoplastic constitutive model (simplified single-boundary model), and based on the undrained shear strength of the soil ( The variation of soil parameters with depth determines the soil mass parameters; Based on engineering practice and hydraulic model tests, the geometry of local scour pits is simplified to an inverted conical geometry surrounding each pile, with a pre-set slope (in this embodiment of the invention, it is set as follows). ), and scouring depth ( ) is a variable parameter (0 to multiple times the pile diameter (e.g.) , (for pile diameter), such as Figure 3 As shown.

[0031] The pile-soil interface is defined as frictional contact, the displacement at the bottom of the soil domain is constrained, and kinematic coupling constraints are applied to the lateral boundaries to simulate a semi-infinite foundation.

[0032] The wind turbine tower constructed using spatial beam elements is segmented, with each segment assigned different cross-sectional properties.

[0033] The total mass of the nacelle and rotor is simplified and simulated using the lumped mass method, specifically as follows: The total mass of the rotor-nacelle assembly is concentrated at the top of the tower. The horizontal offset distance of the rotor's center of mass relative to the nacelle's center of mass is set. The moment of inertia of the rotor about the three coordinate axes is calculated according to the following formula, and the moment of inertia is set at the concentrated mass point of the rotor-nacelle assembly.

[0034] in, , , These are the moments of inertia along the three coordinate axes, respectively. , These refer to the mass and length of the wind turbine blades, respectively. This is the horizontal offset distance of the rotor's center of mass relative to the nacelle's center of mass.

[0035] The process of establishing a coupled finite element model of the pile-soil-jacket wind turbine structure, including parameterized local scour pits, also includes: performing wind turbine frequency tuning design to consider dynamic stability, specifically: By adjusting the cross-sectional stiffness properties of the jacket and pile body, the basic natural frequency of the structure under controlled scour conditions is kept far away from the operating frequency range of the rotor rotation frequency (1P) and blade passing frequency (3P) of the wind turbine, laying a stable foundation for subsequent analysis.

[0036] The following steps are used to identify and define the most representative combination of hazard loads for analysis: Based on the seismic response spectrum at the natural frequency of the unscourized state of the model and the hydrogeological conditions of the site, the controlling ground motion and a series of analysis conditions with increasing scour depth were determined, specifically: The fundamental natural frequency of the model under scour-free conditions was calculated, and multiple seismic ground motion records with significant seismic response spectrum values ​​at the fundamental natural frequency were selected from the seismic ground motion database as control ground motions. These seismic records consisted of acceleration time history data from different seismic events, with a time step of 0.02 s to extract time history point data. The peak ground acceleration of all records was then uniformly modulated to 0.3g. Based on the acceleration time history data, the seismic response spectrum value at the fundamental natural frequency was calculated. The control ground motion was determined based on the acceleration seismic response spectrum, combined with Fourier time history data and earthquake duration for auxiliary analysis. Figure 4 As shown; Based on the hydrogeological conditions of the site, the maximum potential equilibrium scour depth is predicted, and a series of analytical conditions with increasing scour depths are set up with the maximum equilibrium scour depth as the upper limit (e.g.: (This is to systematically study the impact of scouring development.)

[0037] Step 2: Input the control ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition, and perform nonlinear dynamic time history analysis under each combination of control ground motion and scour depth.

[0038] Before performing dynamic analysis, it is necessary to eliminate the initial displacement and unbalanced forces generated by the model under its own weight to obtain a stable and realistic initial stress field. Therefore, before inputting the control ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition and performing nonlinear dynamic time history analysis under each combination of control ground motion and scour depth, the following steps are also included: For each scour depth analysis condition, a static general analysis was performed on the coupled finite element model of the pile-soil-jacket wind turbine structure. An iterative calculation method was used, importing the database file output from the previous geostress analysis step into the predefined field of the subsequent static general analysis step to ensure the accuracy of the starting point for the dynamic response. Figure 5 As shown. The displacement field and reaction force of the model after equilibrium are checked to ensure they are close to zero. The stable initial state is then imported as the initial state for the nonlinear dynamic time history analysis to ensure a stable initial state is obtained.

[0039] Nonlinear dynamic time histories include: displacement time histories, acceleration time histories, pile bending moments, shear forces, axial force distribution time histories, and stress time histories of key nodes in the jacket structure.

[0040] This step uses ABAQUS finite element analysis software, selecting the dynamic implicit analysis step for calculation. The total step size is set to 30s, the initial analysis step size is 0.001s, and the maximum incremental step size is 0.1s. In the field output module, the result output frequency for this dynamic implicit analysis step is set to once every 0.02s. The software calculates and records the various dynamic response parameters of the entire structure in the time domain.

[0041] Step 3: Compare the overall dynamic response of the structure and the distribution of internal forces and displacements in the pile body under different scour depths to assess the coupling effect of earthquake and scour.

[0042] Overall dynamic response, including: fundamental frequency variation of the structure, peak displacement and acceleration at the top of the tower, and overall tilt angle; internal force and displacement distribution of the pile, including: peak bending moment and location along the pile, peak lateral displacement and location, and pile rotation angle distribution; assessment of the coupling effect of earthquake and scour, including: identifying the response parameters most sensitive to scour depth and determining the pile depth region where the scour amplification effect is most significant.

[0043] Finally, a comprehensive dynamic response analysis report is generated, which clearly identifies the structural weaknesses and key response values ​​under the most unfavorable coupling conditions.

[0044] The lateral displacement cloud diagram and the vertical displacement cloud diagram of the four-pile jacket foundation are shown below. Figure 6 , Figure 7 As shown, it is easy to see that the jacket foundation has a large bending stiffness and the foundation displacement changes little under the influence of seismic loads and scour pits, demonstrating good anti-overturning ability.

[0045] Example 2: Embodiment 2 of the present invention discloses a simulation and calculation system for the dynamic response of a four-pile jacket offshore wind turbine under the coupled effects of scour and seismic forces, comprising: Model building and control load condition determination module: used to establish a coupled finite element model of the pile-soil-jacket wind turbine structure containing parameterized local scour pits, and to determine the control ground motion and a series of analysis conditions with increasing scour depth based on the seismic response spectrum value at the natural frequency of the model in the unscour state and the hydrogeological conditions of the site.

[0046] Nonlinear dynamic time history analysis module: This module is used to input the control ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition, and to perform nonlinear dynamic time history analysis under each combination of control ground motion and scour depth.

[0047] The earthquake and scour coupling effect assessment module is used to compare the overall dynamic response of the structure and the distribution of internal forces and displacements in the pile body under different scour depths in order to assess the coupling effect of earthquake and scour.

[0048] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0049] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic forces, characterized in that, include: Step 1: Establish a coupled finite element model of the pile-soil-jacket wind turbine structure containing parameterized local scour pits, and determine the control ground motion and a series of analysis conditions with increasing scour depth based on the seismic response spectrum at the natural frequency of the model in the unscoured state and the hydrogeological conditions of the site. Step 2: Input the controlled ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition, and perform nonlinear dynamic time history analysis under each combination of controlled ground motion and scour depth. Step 3: Compare the overall dynamic response of the structure and the distribution of internal forces and displacements in the pile body under different scour depths to assess the coupling effect of earthquake and scour.

2. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 1, is characterized in that... In step 1, the coupled finite element model of the pile-soil-jacket wind turbine structure includes the superstructure of the offshore wind turbine, the jacket support structure, the pile foundation, the surrounding soil domain, and the local scour pit; wherein, the superstructure of the offshore wind turbine includes: the wind turbine tower, the nacelle, and the rotor. The wind turbine tower and jacket support structure are simulated using spatial beam elements. The total mass of the nacelle and rotor is simplified and simulated using the lumped mass method. The pile foundation and surrounding soil domain are simulated using solid elements. The surrounding soil domain was simulated using an elastoplastic constitutive model, and the soil parameters were determined based on the variation of the undrained shear strength of the soil with depth. The geometry of the local scour pit is an inverted cone shape with a preset slope, and the scour depth is a variable parameter.

3. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 2, is characterized in that... The wind turbine tower constructed using the spatial beam unit is segmented, with each segment assigned different cross-sectional properties.

4. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 2, is characterized in that... The total mass of the nacelle and rotor is simplified and simulated using the lumped mass method, specifically: The total mass of the rotor-nacelle assembly is concentrated at the top of the tower. The horizontal offset distance of the rotor's center of mass relative to the nacelle's center of mass is set. The moment of inertia of the rotor about the three coordinate axes is calculated according to the following formula, and the moment of inertia is set at the concentrated mass point of the rotor-nacelle assembly. in, , , These are the moments of inertia along the three coordinate axes, respectively. , These refer to the mass and length of the wind turbine blades, respectively. This is the horizontal offset distance of the rotor's center of mass relative to the nacelle's center of mass.

5. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 1, is characterized in that... Step 1, in the process of establishing the coupled finite element model of the pile-soil-jacket wind turbine structure including parameterized local scour pits, also includes: performing wind turbine frequency tuning design, specifically: By adjusting the cross-sectional stiffness properties of the jacket and pile body, the basic natural frequency of the structure under the controlled scouring condition is always kept away from the operating frequency range of the rotor rotation frequency and blade passage frequency during wind turbine operation.

6. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 1, is characterized in that... In step 1, based on the seismic response spectrum at the natural frequency of the model in its unscoured state and the hydrogeological conditions of the site, the controlling ground motion and a series of analytical conditions with increasing scour depth are determined, specifically: The calculation model uses the fundamental natural frequency of the model under scour-free conditions, and selects multiple seismic ground motion records from the seismic ground motion database that have significant seismic response spectrum values ​​at the fundamental natural frequency as control ground motions. These seismic records are acceleration time history data of different seismic events. Based on the acceleration time history data, the acceleration seismic response spectrum value at the fundamental natural frequency can be calculated. The control ground motion is determined based on the acceleration seismic response spectrum value, combined with Fourier time history data and earthquake duration, through auxiliary analysis. Based on the hydrogeological conditions of the site, the maximum potential equilibrium scour depth is predicted, and a series of analytical conditions with increasing scour depths are set with the maximum equilibrium scour depth as the upper limit.

7. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 1, is characterized in that... In step 2, before inputting the controlled ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition, and performing nonlinear dynamic time history analysis under each combination of controlled ground motion and scour depth, the following steps are also included: For each scour depth analysis condition, a static general analysis is performed on the coupled finite element model of the pile-soil-jacket wind turbine structure. An iterative calculation method is used, and the result database file output after the previous geostress analysis step is imported into the predefined field of the subsequent static general analysis step. The displacement field and reaction force of the model after equilibrium are checked to see if they are close to zero. The stable initial state is imported as the initial state of the nonlinear dynamic time history analysis.

8. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 1, is characterized in that... In step 2, the nonlinear dynamic time history includes: displacement time history, acceleration time history, pile bending moment, shear force, axial force distribution time history, and stress time history of key nodes of the jacket structure.

9. The method for simulating and calculating the dynamic response of a four-pile jacket offshore wind turbine considering the coupled effects of scour and seismic action, as described in claim 1, is characterized in that... In step 3, the overall dynamic response includes: the fundamental frequency change of the structure, the peak displacement and acceleration at the top of the tower, and the overall tilt angle; the distribution of internal forces and displacements in the pile body includes: the peak bending moment and location distributed along the pile body, the peak lateral displacement and location, and the distribution of pile body rotation angle; the evaluation of the coupling effect of earthquake and scour includes: identifying the response parameters most sensitive to scour depth and determining the pile body depth region where the scour amplification effect is most significant.

10. A system for simulating the dynamic response of a four-pile jacket offshore wind turbine under the coupled effects of scour and seismic forces, utilizing the method for simulating the dynamic response of a four-pile jacket offshore wind turbine under the coupled effects of scour and seismic forces as described in any one of claims 1-9, characterized in that, include: Model building and control load condition determination module: used to establish a coupled finite element model of the pile-soil-jacket wind turbine structure containing parameterized local scour pits, and determine the control ground motion and a series of analysis conditions with increasing scour depth based on the seismic response spectrum value at the natural frequency of the model in the unscour state and the hydrogeological conditions of the site. Nonlinear dynamic time history analysis module: used to input the control ground motion into the coupled finite element model of the pile-soil-jacket wind turbine structure under each scour depth analysis condition, and to perform nonlinear dynamic time history analysis under each combination of control ground motion and scour depth. The earthquake and scour coupling effect assessment module is used to compare the overall dynamic response of the structure and the distribution of internal forces and displacements in the pile body under different scour depths in order to assess the coupling effect of earthquake and scour.

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