Method for optimizing cross section of large-diameter offshore wind power hollow interlayer concrete filled steel tube combined single pile foundation

Abstract

The invention provides a cross section optimization method for a large-diameter offshore wind power hollow interlayer steel pipe concrete combined single pile foundation, which comprises the following steps of: digitally coding cross section parameters of the steel-concrete combined single pile foundation, setting an optimization target and a constraint condition, selecting a design variable range and generating an initial population; each individual represents a different section combination scheme; then, the fitness value of each section combination scheme of the steel-concrete combined single pile foundation is calculated, and multi-target Pareto layered screening is adopted for evaluation; finally, carrying out crossover operation on the selected steel-concrete combined single pile foundation section combination scheme to generate a new section combination scheme, and carrying out tiny random variation on section parameters of part of individuals through a set variation probability; and fitness evaluation, crossing and mutation operations are repeated, and through multi-generation evolution, a steel-concrete combined single-pile foundation section combination scheme conforming to the bending resistance and the total quality evaluation index of the inner and outer steel pipes is finally obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of large-diameter offshore wind power monopile foundation structure optimization, and specifically relates to a method for optimizing the cross-section of a large-diameter offshore wind power hollow sandwich steel tube concrete combined monopile foundation. Background Art

[0002] With the growing global demand for clean energy, offshore wind power has gradually become an important development direction in the field of renewable energy. However, the development of offshore wind power resources has gradually become saturated, and the development potential of deep-sea wind power has attracted much attention. However, the deep-sea environment is more complex, which places higher requirements on the performance of wind power foundation structures. Traditional single pile foundations are difficult to adapt to the load requirements in deep-sea environments due to their limited design and bearing capacity. For this reason, a new type of large-diameter offshore wind power hollow sandwich steel tube concrete composite single pile foundation came into being, aiming to improve the stability and durability of the structure and provide a more reliable support form for deep-sea wind power.

[0003] However, how to achieve economy and efficiency while meeting the structural performance has become a key issue in the design of this new type of monopile foundation. By rationally optimizing the cross-sectional dimensions, designers can not only significantly improve the bending resistance and overall stability of the structure, thereby more effectively resisting external forces such as ocean wind loads, but also reduce material usage and construction costs, making the design of hollow sandwich steel tube concrete composite monopile foundation more economical and sustainable. At present, there has been no research on the optimization of the cross-sectional area of ​​large-diameter offshore wind power hollow sandwich steel tube concrete composite monopile foundations, and further exploration and innovation are urgently needed to achieve an efficient and reliable optimization design solution. Summary of the invention

[0004] In view of the problem that traditional single pile foundations in deep water areas have a single structure, insufficient bending resistance and stability, and cannot meet the design and use requirements, the present invention proposes a cross-section optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation, which can effectively control the material consumption while improving the bending resistance and stability of the foundation.

[0005] The method first digitally encodes the cross-sectional parameters of the steel-concrete composite monopile foundation, sets the optimization objectives and constraints, selects the design variable range and generates the initial population to ensure that each individual represents a different cross-sectional combination scheme; then calculates the fitness value of each cross-sectional combination scheme of the steel-concrete composite monopile foundation, and adopts multi-objective Pareto hierarchical screening to evaluate it. At the same time, combined with the adaptive selection mechanism, roulette selection is used to enhance the population diversity within the first 20% generations of the algorithm iteration; when the number of iterations exceeds the set number of generations, it switches to tournament selection to focus on retaining individuals with high fitness and further promote the optimization of the population; finally, the selected cross-sectional combination schemes of the steel-concrete composite monopile foundation are cross-operated to generate new cross-sectional combination schemes, and the cross-sectional parameters of some individuals are slightly randomly mutated by the set mutation probability; repeats the fitness evaluation, adaptive selection, cross-over and mutation operations, and after multiple generations of evolution, finally obtains the cross-sectional combination scheme of the steel-concrete composite monopile foundation with good bending performance and moderate total mass of the inner and outer steel pipes. The present invention combines genetic algorithms to improve the bending resistance and stability of large-diameter offshore wind power hollow sandwich steel tube concrete composite single pile foundations by optimizing cross-sectional dimensions, so that the foundation can effectively control material usage while meeting engineering requirements.

[0006] The technical solution specifically adopted by the present invention to solve the technical problem is:

[0007] A cross-sectional optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete composite monopile foundation is proposed. First, the cross-sectional parameters of the steel-concrete composite monopile foundation are digitally encoded, the optimization objectives and constraints are set, the design variable range is selected and the initial population is generated to ensure that each individual represents a different cross-sectional combination scheme. Then, the fitness value of each cross-sectional combination scheme of the steel-concrete composite monopile foundation is calculated, and multi-objective Pareto hierarchical screening is used for evaluation. Finally, a cross-sectional combination scheme is performed on the selected steel-concrete composite monopile foundation cross-sectional combination scheme to generate a new cross-sectional combination scheme, and the cross-sectional parameters of some individuals are slightly randomly mutated by the set mutation probability. The fitness evaluation, cross-sectional and mutation operations are repeated, and after multiple generations of evolution, a cross-sectional combination scheme of the steel-concrete composite monopile foundation that meets the bending performance and the evaluation index of the total quality of the inner and outer steel pipes is finally obtained.

[0008] Furthermore, in the process of evaluation using multi-objective Pareto stratified screening, combined with the adaptive selection mechanism, roulette wheel selection is used to enhance population diversity within the first 20% generations of the algorithm iteration; when the number of iterations exceeds the set generation, it switches to tournament selection to focus on retaining high fitness individuals and further promote the optimization of the population; fitness evaluation, adaptive selection, crossover and mutation operations are repeated for iteration.

[0009] Furthermore, the cross-sectional parameters of the steel-concrete composite single pile foundation are digitally encoded, the optimization objectives and constraints are set, and the design variable range is selected, specifically including:

[0010] The outer diameter of the steel pipe D 外 、Inner diameter of steel pipe D 内 , outer tube wall thickness t 外 , inner tube wall thickness t 内 as design variables;

[0011] The objective function of the steel-concrete composite single pile foundation is set to minimize the total mass of the inner and outer steel pipes and maximize the bending stiffness. The constraints are the basic diameter-to-thickness ratio, slenderness ratio, hollow ratio, axial compressive stable bearing capacity and bending bearing capacity:

[0012] Total mass of inner and outer steel pipes:

[0013]

[0014] L is the length of the steel pipe; ρs is the density of the steel pipe;

[0015] Bending stiffness:

[0016]

[0017] In the formula, E S is the elastic modulus of the steel pipe, E C is the elastic modulus of concrete;

[0018] Diameter-to-thickness ratio:

[0019]

[0020]

[0021] In the formula, f y is the yield strength of steel;

[0022] Slenderness ratio:

[0023]

[0024] Hollow rate:

[0025] 0.25≤η≤0.75 (7)

[0026]

[0027] In the formula, A k is the area of ​​the hollow part, A sc is the total area of ​​the inner steel pipe and concrete;

[0028] Axial compression stability bearing capacity constraints:

[0029]

[0030] Where: N is the design value of the axial pressure, N u is the design value of the axial compressive bearing capacity of the steel tube concrete member, N0 is the design value of the axial compressive strength bearing capacity of the hollow steel tube concrete short column, is the stability factor of the axially compressed member, λ sc is the slenderness ratio of the component, λ sc is the regular slenderness ratio of the component;

[0031] Constrained by bending capacity:

[0032] M≤M u (13)

[0033] M u =γ m W sc f sc (14)

[0034]

[0035] Where: M is the design value of bending moment, M u is the design value of axial bending bearing capacity of concrete-filled steel tube members, f sc is the design value of compressive strength of hollow steel tube concrete, γ m is the plastic development coefficient, r0 is the equivalent circle radius, r ci is the hollow radius, W sc is the section modulus of the flexural member, and θ is the hoop coefficient.

[0036] Furthermore, the generating of the initial population specifically includes: initializing genetic algorithm parameters, including population size, maximum evolutionary generations, crossover probability and mutation probability, so as to ensure the diversity and global search capability of the optimization process.

[0037] Furthermore, in the process of calculating the fitness value of each cross-section combination scheme of the steel-concrete composite single pile foundation and evaluating it by multi-objective Pareto hierarchical screening:

[0038] For each cross-section combination individual, the total mass and bending stiffness of the inner and outer steel pipes are calculated respectively, and the total mass and bending stiffness of the inner and outer steel pipes of all individuals are standardized respectively; the non-dominated sorting method is used to stratify the individuals according to the comprehensive performance of the total mass and bending stiffness of the inner and outer steel pipes, and the individuals that cannot meet the requirements of the total mass and bending stiffness of the inner and outer steel pipes at the same time are removed from each layer;

[0039] For each layer of individuals, a weighted combined fitness value is calculated based on the normalized values ​​of the total mass and bending stiffness of the inner and outer steel pipes:

[0040] f(ω)=ω1·f1+ω2·(-f2) (17)

[0041] In the formula, ω1 and ω2 are weights, ω1+ω2=1; f1 and f2 are the total mass and bending stiffness of the inner and outer steel pipes, respectively. The negative sign of f2 is added to transform both objective functions into minimization problems to facilitate the solution of the model.

[0042] Furthermore, in each generation of updates, individuals with high fitness in the top 20% of the Pareto hierarchy are prioritized to ensure the stability of the optimization direction. At the same time, to avoid premature convergence, individuals with medium and low fitness in the last 80% of the hierarchy are allowed to enter the next generation population with a certain probability, thereby maintaining population diversity. The fitness value of each individual will be returned to the population, allowing it to perform adaptive selection based on the fitness value in subsequent selections.

[0043] A large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation section optimization system, comprising:

[0044] Digital coding module, used to digitally code the cross-sectional parameters of the steel-concrete composite monopile foundation, set the optimization objectives and constraints, and select the range of design variables;

[0045] The iterative evolution module is used to generate the initial population to ensure that each individual represents a different cross-section combination scheme; the fitness value of each cross-section combination scheme of the steel-concrete composite monopile foundation is calculated, and multi-objective Pareto hierarchical screening is used for evaluation; finally, a crossover operation is performed on the selected cross-section combination schemes of the steel-concrete composite monopile foundation to generate a new cross-section combination scheme, and the cross-section parameters of some individuals are slightly randomly mutated through the set mutation probability; the fitness evaluation, crossover and mutation operations are repeated, and after multiple generations of evolution, a steel-concrete composite monopile foundation cross-section combination scheme that meets the bending performance and the total quality evaluation indicators of the internal and external steel pipes is finally obtained.

[0046] Furthermore, the iterative evolution module, in the process of evaluating by multi-objective Pareto hierarchical screening, combines an adaptive selection mechanism and uses roulette wheel selection to enhance population diversity within the first 20% generations of algorithm iterations; when the number of iterations exceeds the set number of generations, switches to tournament selection to focus on retaining individuals with high fitness, further promoting population optimization; and repeats fitness evaluation, adaptive selection, crossover and mutation operations for iteration.

[0047] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the above-mentioned method for optimizing the cross-section of a large-diameter offshore wind power hollow sandwich steel tube concrete composite single pile foundation are implemented.

[0048] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for optimizing the cross-section of a large-diameter offshore wind power hollow sandwich steel tube concrete composite single pile foundation.

[0049] Compared with the prior art, the present invention and its preferred solution adopt the dual-objective optimization form of the total mass of the inner and outer steel pipes and the bending stiffness, which can ensure that the foundation structure can meet the bending performance while minimizing the use of materials, thereby improving the economy and sustainability of the overall project. In a further preferred solution, an adaptive selection mechanism is adopted, so that the selection strategy can be flexibly adjusted according to the state of the population during the optimization process, maintaining the diversity of the population at different stages and preventing premature convergence. Ensure that the algorithm always maintains efficient search capabilities at different stages of progress, thereby greatly improving the efficiency of the optimization process and the accuracy of the results. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0051] Figure 1 This is a flow chart for optimizing the cross section of a hollow sandwich steel tube concrete combined single pile foundation according to an embodiment of the present invention;

[0052] Figure 2 It is a schematic diagram of cross-section optimization parameters of a hollow sandwich steel tube concrete combined single pile foundation according to an embodiment of the present invention;

[0053] Figure 3 This is a relationship diagram between the bending stiffness and the total mass of the inner and outer steel pipes during the cross-section optimization process of the hollow sandwich steel tube concrete combined single pile foundation in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows:

[0055] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0056] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0057] like Figure 1 As shown, the present invention provides a method for optimizing the cross-section of a large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation, and its basic implementation process may include the following four steps:

[0058] Step S1: digitally encode the cross-sectional parameters of the steel-concrete composite monopile foundation, initialize the optimization algorithm parameters, select the design variable range and set the optimization target and constraints, generate the initial population, and ensure that each individual represents a different cross-sectional combination scheme;

[0059] Initialize the genetic algorithm parameters, including population size, maximum evolutionary generations, crossover probability, and mutation probability, to ensure the diversity and global search capability of the optimization process; Figure 2 As shown, select the outer diameter D of the steel pipe 外 、Inner diameter of steel pipe D 内 , outer tube wall thickness t 外 , inner tube wall thickness t 内 As design variables and select the variation range:

[0060] 7m≤D 外 ≤12 m (1)

[0061] 7m≤D 内 ≤12m (2)

[0062] 0.01m≤t 外 ≤0.15m (3)

[0063] 0.01m≤t 内 ≤0.15m (4)

[0064] The objective function of the steel-concrete composite single pile foundation is determined to minimize the total mass of the inner and outer steel pipes and maximize the bending stiffness. The constraints are the diameter-to-thickness ratio, slenderness ratio, hollow ratio, axial compressive stable bearing capacity and bending bearing capacity of the foundation:

[0065] ①Total mass of inner and outer steel pipes:

[0066]

[0067] ② Bending stiffness:

[0068]

[0069] In the formula, E S is the elastic modulus of the steel pipe, E C is the elastic modulus of concrete;

[0070] The constraints that meet the structural requirements include the diameter-to-thickness ratio, slenderness ratio, and hollowness ratio of the foundation;

[0071] ①Diameter-to-thickness ratio:

[0072]

[0073] In the formula, f y is the yield strength of steel;

[0074] ② Slenderness ratio:

[0075]

[0076] ③ Hollowness rate:

[0077] 0.25≤η≤0.75 (11)

[0078]

[0079] In the formula, A k is the area of ​​the hollow part, A sc is the total area of ​​inner steel pipe and concrete

[0080] The constraints that meet the strength requirements include the axial compressive stability bearing capacity and bending bearing capacity of the foundation;

[0081] ①Axial compression stability bearing capacity constraint:

[0082]

[0083]

[0084] Where: N is the design value of the axial pressure, N u is the design value of the axial compressive bearing capacity of the steel tube concrete member, N0 is the design value of the axial compressive strength bearing capacity of the hollow steel tube concrete short column, is the stability factor of the axially compressed member, λ sc is the slenderness ratio of the component, λ sc is the normal slenderness ratio of the component.

[0085] ②Constrained by bending capacity:

[0086] M≤M u (17)

[0087] M u =γ m W sc f sc (18)

[0088]

[0089] Where: M is the design value of bending moment, M u is the design value of axial bending bearing capacity of concrete-filled steel tube members, f sc is the design value of compressive strength of hollow steel tube concrete, γ mis the plastic development coefficient, r0 is the equivalent circle radius, r ci is the hollow radius, W sc is the section modulus of the flexural member, and θ is the hoop coefficient.

[0090] Step S2: Calculate the fitness value of each cross-section combination scheme of the steel-concrete composite single pile foundation, and use multi-objective Pareto hierarchical screening to evaluate it. At the same time, combine the adaptive selection mechanism, and use roulette selection to enhance population diversity within the first 20% of the algorithm iterations; when the number of iterations exceeds the set number of generations, switch to tournament selection to focus on retaining individuals with high fitness and further promote the optimization of the population;

[0091] For each cross-section combination individual, the total mass and bending stiffness of the inner and outer steel pipes are calculated respectively, and the total mass and bending stiffness of the inner and outer steel pipes of all individuals are standardized respectively. The non-dominated sorting method is used to stratify the individuals according to the comprehensive performance of the total mass and bending stiffness of the inner and outer steel pipes, and the individuals that cannot meet the requirements of the total mass and bending stiffness of the inner and outer steel pipes at the same time are removed from each layer;

[0092] For each layer of individuals, a weighted combined fitness value is calculated based on the normalized values ​​of the total mass and bending stiffness of the inner and outer steel pipes:

[0093] f(ω)=ω1·f1+ω2·(-f2) (21)

[0094] In the formula, ω1 and ω2 are weights, ω1+ω2=1; f1 and f2 are the total mass and bending stiffness of the inner and outer steel pipes, respectively. The negative sign of f2 is added to transform both objective functions into minimization problems to facilitate the solution of the model.

[0095] In each generation of updates, high fitness individuals in the top 20% of the Pareto hierarchy are prioritized to ensure the stability of the optimization direction. At the same time, to avoid premature convergence, medium and low fitness individuals in the last 80% of the hierarchy are allowed to enter the next generation population with a certain probability, thereby maintaining population diversity. The fitness value of each individual will be returned to the population, so that it can be adaptively selected based on the fitness value in subsequent selections. The fitness value of each individual is returned to the population, so that it can be adaptively selected based on the fitness value in subsequent selections.

[0096] Step S3: performing a cross operation on the selected steel-concrete composite single pile foundation section combination schemes to generate a new section combination scheme, and performing a slight random mutation on the section parameters of some individuals through a set mutation probability;

[0097] Step S4: Repeat step S2 and step S3. After multiple generations of evolution, a steel-concrete composite single pile foundation section combination scheme with good bending resistance and moderate total mass of inner and outer steel pipes is finally obtained.

[0098] like Figure 3 As shown in the figure, it is the Pareto frontier obtained through iterative evolution, which reflects the optimal compromise between the total mass of the inner and outer steel pipes and the bending stiffness. The horizontal axis represents the total amount of steel used in the design, and the vertical axis represents the bending stiffness. The negative value is used to unify it with the optimization target of the amount of steel used as a minimization problem. Each point in the figure represents a Pareto optimal solution, at which the optimal balance is achieved between the total mass of the inner and outer steel pipes and the bending stiffness, and one goal cannot be further improved without compromising the other. Through this process, the optimal choice of different cross-sectional combinations is obtained, and with reference to the single pile foundation before optimization, the cross-sectional dimensions of the hollow sandwich steel tube concrete composite single pile foundation are finally obtained as shown in Table 1.

[0099] After optimization by the present invention, the total mass of the inner and outer steel pipes of the hollow sandwich steel tube concrete combined single pile foundation remains basically unchanged, and the bending resistance of the structure is significantly improved.

[0100] Table 1 Optimized cross-sectional dimensions

[0101]

[0102] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0103] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0104] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0105] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0106] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0107] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

[0108] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation section optimization methods under the inspiration of this patent. All equal changes and modifications made according to the scope of the patent application of this invention should be covered by this patent.

Claims

1. A cross-section optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation, characterized by: Firstly, the cross-sectional parameters of the steel-concrete composite monopile foundation are digitally encoded, the optimization objectives and constraints are set, the range of design variables is selected and the initial population is generated to ensure that each individual represents a different cross-sectional combination scheme; then the fitness value of each cross-sectional combination scheme of the steel-concrete composite monopile foundation is calculated, and multi-objective Pareto hierarchical screening is used for evaluation; finally, a cross-sectional combination scheme of the selected steel-concrete composite monopile foundation is cross-operated to generate a new cross-sectional combination scheme, and the cross-sectional parameters of some individuals are slightly randomly mutated through the set mutation probability; the fitness evaluation, cross-over and mutation operations are repeated, and after multiple generations of evolution, a cross-sectional combination scheme of the steel-concrete composite monopile foundation that meets the bending performance and the evaluation indicators of the total quality of the inner and outer steel pipes is finally obtained.

2. The cross-section optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation according to claim 1 is characterized by: In the process of evaluation using multi-objective Pareto hierarchical screening, combined with the adaptive selection mechanism, roulette wheel selection is used to enhance population diversity within the first 20% generations of the algorithm iteration; when the number of iterations exceeds the set number of generations, it switches to tournament selection to focus on retaining high fitness individuals and further promote population optimization; fitness evaluation, adaptive selection, crossover and mutation operations are repeated for iteration.

3. The cross-section optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation according to claim 1 is characterized by: The cross-sectional parameters of the steel-concrete composite single pile foundation are digitally encoded, the optimization objectives and constraints are set, and the design variable range is selected, which specifically includes: The outer diameter of the steel pipe D 外 、Inner diameter of steel pipe D 内 , outer tube wall thickness t 外 , inner tube wall thickness t 内 as design variables; The objective function of the steel-concrete composite single pile foundation is set to minimize the total mass of the inner and outer steel pipes and maximize the bending stiffness. The constraints are the basic diameter-to-thickness ratio, slenderness ratio, hollow ratio, axial compressive stable bearing capacity and bending bearing capacity: Total mass of inner and outer steel pipes: L is the length of the steel pipe; ρ s is the density of the steel pipe; Bending stiffness: In the formula, E S is the elastic modulus of the steel pipe, E C is the elastic modulus of concrete; Diameter-to-thickness ratio: In the formula, f y is the yield strength of steel; Slenderness ratio: Hollow rate: 0.25≤η≤0.75 (7) In the formula, A k is the area of ​​the hollow part, A sc is the total area of ​​the inner steel pipe and concrete; Axial compression stability bearing capacity constraints: Where: N is the design value of the axial pressure, N u is the design value of the axial compressive bearing capacity of the steel tube concrete member, N0 is the design value of the axial compressive strength bearing capacity of the hollow steel tube concrete short column, is the stability factor of the axially compressed member, λ sc is the component slenderness ratio, is the regular slenderness ratio of the component; Constrained by bending capacity: M≤M u (13) M u =γ m W sc f sc (14) Where: M is the design value of bending moment, M u is the design value of axial bending bearing capacity of concrete-filled steel tube members, f sc is the design value of compressive strength of hollow steel tube concrete, γ m is the plastic development coefficient, r0 is the equivalent circle radius, r ci is the hollow radius, W sc is the section modulus of the flexural member, and θ is the hoop coefficient.

4. The cross-section optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation according to claim 1 is characterized by: The generating of the initial population specifically includes: initializing the genetic algorithm parameters, including the population size, the maximum number of evolution generations, the crossover probability and the mutation probability, so as to ensure the diversity and global search capability of the optimization process.

5. The cross-section optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation according to claim 1 is characterized by: In the process of calculating the fitness value of each cross-section combination scheme of the steel-concrete composite single pile foundation and evaluating it by multi-objective Pareto hierarchical screening: For each cross-section combination individual, the total mass and bending stiffness of the inner and outer steel pipes are calculated respectively, and the total mass and bending stiffness of the inner and outer steel pipes of all individuals are standardized respectively; the non-dominated sorting method is used to stratify the individuals according to the comprehensive performance of the total mass and bending stiffness of the inner and outer steel pipes, and the individuals that cannot meet the requirements of the total mass and bending stiffness of the inner and outer steel pipes at the same time are removed from each layer; For each layer of individuals, a weighted combined fitness value is calculated based on the normalized values ​​of the total mass and bending stiffness of the inner and outer steel pipes: f(ω)=ω1·f1+ω2·(-f2) (17) In the formula, ω1 and ω2 are weights, ω1+ω2=1; f1 and f2 are the total mass and bending stiffness of the inner and outer steel pipes, respectively. The negative sign of f2 is added to transform both objective functions into minimization problems to facilitate the solution of the model.

6. The cross-section optimization method for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation according to claim 2 is characterized by: In each generation of updates, high fitness individuals in the top 20% of the Pareto hierarchy are retained first to ensure the stability of the optimization direction. To avoid premature convergence, medium and low fitness individuals in the last 80% of the hierarchy are allowed to enter the next generation population with a certain probability, thereby maintaining population diversity. The fitness value of each individual is returned to the population for adaptive selection based on the fitness value in subsequent selections.

7. A large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation cross-section optimization system, characterized in that: include: Digital coding module, used to digitally code the cross-sectional parameters of the steel-concrete composite monopile foundation, set the optimization objectives and constraints, and select the range of design variables; Iterative evolution module, used to generate the initial population to ensure that each individual represents a different cross-sectional combination scheme; The fitness value of each cross-section combination scheme of the steel-concrete composite monopile foundation is calculated, and multi-objective Pareto hierarchical screening is used for evaluation; finally, a cross-section combination scheme of the selected steel-concrete composite monopile foundation is cross-operated to generate a new cross-section combination scheme, and the cross-section parameters of some individuals are slightly randomly mutated through the set mutation probability; the fitness evaluation, cross-over and mutation operations are repeated, and after multiple generations of evolution, the steel-concrete composite monopile foundation cross-section combination scheme that meets the bending performance and the total quality evaluation indicators of the internal and external steel pipes is finally obtained.

8. The cross-section optimization system for large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation according to claim 7 is characterized by: The iterative evolution module uses a multi-objective Pareto hierarchical screening process for evaluation, combined with an adaptive selection mechanism, to use roulette wheel selection to enhance population diversity within the first 20% of the algorithm iterations; when the number of iterations exceeds the set number of generations, it switches to tournament selection to focus on retaining individuals with high fitness and further promote population optimization; and iterates by repeating fitness evaluation, adaptive selection, crossover and mutation operations.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the cross-section optimization method of large-diameter offshore wind power hollow sandwich steel tube concrete combined single pile foundation as described in any one of claims 1-6 are implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for optimizing the cross-section of a large-diameter offshore wind power hollow sandwich steel tube concrete composite single pile foundation as described in any one of claims 1 to 6 are implemented.

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