Accurate calculation method for horizontal bearing capacity of offshore wind power foundation

Abstract

The application belongs to the technical field of foundation horizontal bearing capacity calculation, and specifically discloses a kind of offshore wind power foundation horizontal bearing capacity accurate calculation method, the method comprises: integrating wave spectrum, wind condition, tide and soil parameters to form multidimensional data set;Three-dimensional pile soil model is constructed and wave force and wind load are coupled;Stiffness coefficient is calculated and combined with length-diameter ratio to identify pile type;According to the type of pile, the environmental deviation compensation coefficient is quantified;After calculating the preliminary horizontal bearing capacity, the bearing capacity failure critical state is judged based on real-time displacement monitoring data, if the critical state is reached, the preliminary bearing capacity is modified by linear weighting of displacement deviation compensation coefficient and environmental deviation compensation coefficient.The application dynamically couples time-varying environmental load, simulates the interaction between pile and soil in detail, establishes a stiffness self-adaptive grading mechanism and a double compensation feedback system, significantly improving the accuracy and real-time warning capability of horizontal bearing capacity calculation in complex marine environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of foundation horizontal bearing capacity calculation, and particularly relates to a method for accurately calculating the horizontal bearing capacity of an offshore wind power foundation. BACKGROUND

[0002] As an important field of clean energy development, offshore wind power requires its infrastructure to withstand complex horizontal loads such as waves, wind, ocean currents, and occasional loads such as ship impact for a long time. The horizontal bearing capacity is a core indicator that determines the safety and economy of the foundation structure, and its calculation accuracy is self-evident.

[0003] The prior art, such as the method for calculating the horizontal bearing capacity of a five-jacket foundation for offshore wind power disclosed in Chinese patent application No. 202411294786.2, defines the vertical soil resistance distribution by equating the area of the five-jacket foundation to that of a single-jacket foundation and includes the friction generated by the interaction between the cylinder and the soil. Based on the static equilibrium relationship, the ultimate load is determined, thereby effectively transferring the horizontal load of offshore wind power equipment, improving the overall structural stability, and ensuring safe operation in adverse sea conditions.

[0004] For the above technical solution, it is obvious that the special environment of offshore is not fully considered, and there are still several deficiencies in the following aspects: 1. The time-varying environmental loads such as wave spectrum, wind conditions, and tides and their interactions are ignored, and the dynamic coupling effect of multi-source loads in the real marine environment and its real-time influence on the bearing capacity cannot be reflected.

[0005] 2. The existing technology mainly considers the effect of loads on the overall foundation, lacks detailed simulation of how wave forces and wind loads are specifically transmitted and coupled to the internal structure of the pile body, and does not consider the differentiated response mechanism of horizontal loads for different pile types. This simplification hides the influence of local stress concentration or complex load paths, and also leads to deviations between the calculation results and the actual situation.

[0006] 3. The existing technology determines the bearing capacity based on the limit state static equilibrium, lacks the ability to determine whether it is close to the failure critical state based on real-time displacement monitoring data during operation, and also lacks a feedback mechanism for dynamically correcting the calculation results based on the monitoring displacement deviation and the actual environmental load influence, resulting in the difficulty of achieving the expected accuracy of the calculation results. SUMMARY

[0007] In view of this, in order to solve the above problems, a method for accurately calculating the horizontal bearing capacity of an offshore wind power foundation is proposed.

[0008] The object of the present application can be achieved by the following technical solutions: The present application provides a method for accurately calculating the horizontal bearing capacity of offshore wind power foundation, which comprises the following steps: S1, multi-source environmental data integration: collecting wave spectrum parameters, wind distribution data, tidal parameters and soil layering parameters in the current monitoring period, and integrating them into a multi-dimensional data set.

[0009] S2, multi-scale coupling model construction: a three-dimensional pile-soil model is established, and wave force and wind load are coupled to the pile body.

[0010] S3, dynamic classification of pile body stiffness: the stiffness coefficient is calculated based on the three-dimensional pile-soil model, and the pile body type is identified according to the corresponding relationship between the coefficient and the length-diameter ratio, wherein the pile body type is one of rigid pile, rigid-flexible pile and flexible pile.

[0011] S4, environmental load interference quantification: combining the multi-dimensional data set and the pile body type, the environmental deviation compensation coefficient is quantified.

[0012] S5, bearing capacity calculation and determination: the preliminary horizontal bearing capacity is calculated according to the pile body type, and whether the bearing capacity failure critical state is reached is judged based on the pile body displacement data in the current monitoring period, if the critical state is reached, the displacement deviation compensation coefficient is set, and the preliminary horizontal bearing capacity is modified by the environmental deviation compensation coefficient and the displacement deviation compensation coefficient to output the final horizontal bearing capacity.

[0013] Compared with the prior art, the present application has the following advantages: (1) The present application forms a time-space-parameter multi-dimensional data set by integrating wave spectrum parameters, wind distribution data, tidal parameters and soil layering parameters, which completely captures the time-varying characteristics of waves, wind and tides and their interaction. Further, it provides real environmental input for the three-dimensional pile-soil model, accurately reflects the real-time influence of multi-source load dynamic coupling on pile bearing capacity, and overcomes the deviation caused by simplifying environmental load in the prior art.

[0014] (2) The present application establishes a three-dimensional pile-soil model and couples wave force and wind load, accurately simulates the transmission process of wave force and wind load to the internal structure of the pile body, and reveals the local stress concentration effect and complex load path, avoiding the limitations of the overall simplified model in the prior art.

[0015] (3) The present application realizes the differentiated response characteristics of different stiffness type piles by identifying the pile body type, and significantly improves the accuracy of horizontal load response prediction of various types of piles by matching the exclusive bearing capacity calculation rules.

[0016] (4) The present application compares model response data with field measured data, locates deviation period and associates environmental load characteristics, combines pile type classification to quantize environmental deviation compensation coefficient, and then real-time corrects model and actual environmental load difference, ensures that the calculation result adapts to the dynamic change of complex marine working conditions, and through the double coefficient correction of the environmental deviation compensation coefficient and the displacement deviation compensation coefficient, the accuracy of the calculation result is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] Figure 1 The present application is a whole implementation flowchart.

[0019] Figure 2 The present application is a critical overturning state recognition flowchart.

[0020] Figure 3 The present application is a pile type recognition flowchart.

[0021] Figure 4 The present application is a bearing capacity failure critical state judgment flowchart.

[0022] Figure 5 The present application is a three-dimensional pile soil model structure diagram.

[0023] Figure 6 The present application is a three-dimensional pile soil model different radial size comparison diagram.

[0024] Figure 7 The present application is a three-dimensional pile soil model different axial size comparison diagram.

[0025] Figure 8 The present application is a clay soil time different diameter, different length-diameter ratio corresponding pile body displacement comparison diagram.

[0026] Figure 9 The present application is a sand soil time different diameter, different length-diameter ratio corresponding pile body displacement comparison diagram. DETAILED DESCRIPTION

[0027] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0028] Please refer to Figure 1 As shown in the drawings, the present application provides a method for accurately calculating the horizontal bearing capacity of an offshore wind power foundation, which comprises the following steps: S1, multi-source environmental data integration: collecting wave spectrum parameters, wind distribution data, tidal parameters and soil layering parameters in the current monitoring period, and integrating them into a multi-dimensional data set.

[0029] Specifically, the specific execution process of S1 step is as follows: wave monitoring buoys are arranged in the sea area where the wind power facility is located, and wave spectrum is generated by collecting wave instantaneous amplitude, period and propagation direction through the wave monitoring buoys.

[0030] The instantaneous wind speed and direction at different heights are collected through the meteorological monitoring station, the wind speed profile is generated by hour, and the wind distribution data is obtained by identifying the gust characteristics.

[0031] The tidal level change is recorded through the tidal station or water level sensor, and the tidal parameters are obtained by extracting the ebb and flow time, tidal range and high and low tide time.

[0032] The soil mechanical parameters around the pile are obtained through static sounding or vane shear test, the soil layering boundary and physical properties are determined by combining with the borehole sampling, and the soil layering parameters are obtained.

[0033] The wave spectrum energy peak time, the wind speed profile peak time and the high and low tide time are aligned by time stamp.

[0034] All data are integrated according to the three-dimensional structure of time, space and parameter type to generate the multi-dimensional data set.

[0035] It should be noted that the gust characteristics include but are not limited to the maximum instantaneous wind speed of gust, the duration of gust and the frequency of gust, which can be determined after statistical analysis such as moving average, peak extraction and cycle identification.

[0036] It should be noted that the soil mechanical parameters around the pile include but are not limited to the cone tip resistance, the side wall friction resistance, the friction ratio, the pore water pressure and the undrained shear strength, and the physical properties include but are not limited to the particle composition and the plasticity index.

[0037] S2, multi-scale coupling model construction: a three-dimensional pile-soil model is established, and the wave force and wind load are coupled to the pile body.

[0038] Specifically, the specific implementation process of the S2 step is as follows: S21, a three-dimensional pile-soil model is constructed in the finite element software based on the pile geometric parameters, the soil domain ranges from n times of the pile diameter to m times of the pile length, the bottom and the lateral direction are provided with fixed boundaries, and the top is provided with a free boundary, and n and m are constants. The three-dimensional pile-soil model can specifically refer to the three-dimensional pile-soil model shown in FIG. 1. Figure 5

[0039] Understandably, the geometric parameters include the pile length and the pile diameter, and under the conventional working condition, the value range of n can be set to 5-10, and the value range of m can be set to 2-3, which can effectively avoid the interference of the lateral fixed boundary on the stress distribution of the soil around the pile and ensure that the influence of the bottom fixed boundary on the stress transmission of the pile end can be ignored.

[0040] It should be noted that constructing the three-dimensional pile-soil model also includes dividing the model units according to the soil layering, wherein the pile body is discretized by using three-dimensional solid elements, the soil body is discretized by using continuous medium elements, and the mesh is encrypted in the pile-soil contact interface area.

[0041] The discretization of the three-dimensional solid element is divided according to the geometric size of the pile body, and the element length in the pile length direction is preferably matched with the pile diameter, for example, 0.5-1 times of the pile diameter, and for the variable cross-section pile, the element division needs to be refined at the cross-section change, and the soil body can specifically use a three-dimensional continuous medium solid element, for example, an 8-node hexahedral element C3D8.

[0042] In one specific embodiment, in order to ensure the fine simulation of the axial and radial mechanical behavior of the pile body, the three-dimensional pile-soil model is analyzed by using 10D, 15D, 20D, 25D, 30D and 35D as the radial boundary, wherein D is the base diameter, and the analysis results are as shown in FIG. 2. Figure 6 The axial size of the three-dimensional pile-soil model is set to L+5D, L+10D, L+15D and L+20D for analysis, wherein L is the pile foundation embedded depth, and the specific analysis results are as shown in FIG. 3. Figure 7 Figure 6 According to the comparison results, 20D is finally used as the radial size of the three-dimensional pile-soil model, and the comparison results are as shown in FIG. 4. Figure 7 According to the comparison results, L+5D is finally used as the axial size of the three-dimensional pile-soil model.

[0043] It should be noted that the mesh setting has a great influence on the finite element results, and mesh sensitivity analysis and calculation need to be performed, the axial mesh size of the soil body and the pile should not be greater than 1m, the minimum radial mesh size of the soil body should not be greater than 0.05 times of the outer diameter of the pile; the vertical foundation boundary of the model should not be less than the sum of the pile embedded depth and 5 times of the outer diameter of the pile, and the horizontal boundary of the model should not be less than 20 times of the outer diameter of the pile. The bottom of the model should be provided with three direction constraints, and the surrounding should be provided with normal constraints.

[0044] ​​Further, the encryption range is centered on the pile-soil contact interface, extending to the interior of the pile body and the surrounding soil body by a certain range, usually 1-2 times the pile diameter as the encryption area, covering the stress and strain concentration zone from the surface of the pile body to the interior of the soil body.

[0045] The encryption method is as follows: for the unit of the pile body side surface and the soil body near the pile end, the unit size is reduced to 1 / 3-1 / 2 of the non-encryption area, and it is gradually transitioned outward from the pile body, such as 0.5 times the pile diameter outwardly, the unit size is increased by 20%-30%, for the pile body unit and the soil body unit directly associated with the contact interface, the common node or matching grid division is adopted to ensure the continuous transmission of force and displacement on the contact surface.

[0046] S22, based on the wave spectrum data, the horizontal impact force and vertical buoyancy of the wave on the pile body are calculated by the fluid mechanics equation, and are converted into wave load at different depths of the pile body and loaded into the model in time sequence.

[0047] In the embodiment, the specific calculation process of the fluid mechanics equation is as follows: first, the wavelength and wave number are determined according to the peak period, the double cosine function value corresponding to the wave number is calculated combined with the water depth, and then the horizontal velocity and acceleration of the water quality point at different depths are obtained according to the significant wave height, the circular frequency converted from the peak period and the water depth direction coordinate, which respectively reflect the speed and speed change rate of the water quality point with the wave movement. Subsequently, the calculation method is selected according to the diameter of the pile body, when the diameter of the pile body is less than the preset diameter, the Morison equation is used, the velocity and acceleration of the water quality point are substituted into the equation to calculate the inertia force caused by the acceleration of the water quality point and the drag force caused by the movement friction of the water quality point, and the horizontal impact force is obtained by superposition, and the vertical dynamic buoyancy is calculated combined with the wave dynamic water pressure. When the diameter of the pile body is greater than the preset diameter, the wave diffraction effect is considered to modify the calculation result of the horizontal force by the diffraction coefficient. Among them, the Morison equation and the diffraction coefficient all adopt the existing general equation, which will not be displayed, and the preset diameter can adopt the empirical value of large direct division, such as 6m.

[0048] Exemplarily, the wave load application process is as follows: the pile body is divided into several segments along the depth, the horizontal impact force and vertical buoyancy of each segment are converted into node load according to the average distribution principle of the nodes at both ends, a time sequence covering multiple wave periods is generated, and finally the time sequence load is synchronously loaded to the corresponding node surface of the three-dimensional model of the pile body, and the model application of the wave load is completed.

[0049] S23, based on the wind distribution data, the horizontal thrust and overturning moment at the top of the pile are calculated, and the horizontal thrust is loaded with the geometric center of the pile top as the reference point according to the wind direction and time sequence, and the overturning moment is synchronously applied along the rotation direction.

[0050] In the embodiment, the calculation process of the pile top horizontal thrust and overturning moment is as follows: the reference water level is set as the average sea level, when the real-time water level is higher than the bottom elevation of the pile body, the submerged segment length is calculated, and the effective windward area is obtained by deducting the lateral projection area of the pile body corresponding to the submerged segment according to the length. Then, the wind load is calculated based on the wind condition distribution data, for example, the 10-minute average wind speed is first corrected to the wind speed at each height according to the power law distribution, and the horizontal thrust is calculated by combining the corrected effective windward area and the shape coefficient of the corresponding structure, and the height of the action point of the resultant force is determined by the weighted average of the windward area of each segment, and then the overturning moment is obtained, which is the product of the horizontal thrust and the height of the action point of the resultant force.

[0051] It should be noted that when the water level changes, the correction process of the submerged segment length, the windward area and the height of the action point of the resultant force needs to be repeated in real time, and the values of the horizontal thrust and the overturning moment need to be adjusted synchronously to ensure that the wind load loading matches the dynamic change of the water level in real time.

[0052] It should be noted that the windward area of the submerged segment of the cylindrical pile body is the product of the circumference of the pile body and the length of the submerged segment, and the effective windward area includes the projection area of the pile top segment, the tower, the cabin and the blades, wherein the shape coefficient of the corresponding structure is as follows: the tower is 0.8-1.2, the cabin is 1.3-1.5, and the blade is 1.0-1.2, and the specific value is obtained according to the corresponding structure matching the preset standard.

[0053] The embodiment of the application accurately simulates the transmission process of the wave force and the wind load to the internal structure of the pile body by establishing a three-dimensional pile-soil model and coupling the wave force and the wind load, and reveals the local stress concentration effect and the complex load path, avoiding the limitations of the existing technology of the overall simplified model.

[0054] S3, dynamic grading of pile body stiffness: based on the three-dimensional pile-soil model, the stiffness coefficient is calculated, and the pile body type is identified according to the corresponding relationship between the coefficient and the length-diameter ratio, wherein the pile body type is one of rigid pile, rigid-flexible pile and flexible pile.

[0055] Specifically, the specific calculation process of the stiffness coefficient is as follows: S3-1, the self-weight load is applied to the three-dimensional pile-soil model for static balance calculation until the stress fluctuation of the pile-soil contact interface is less than a preset value, and then the initial stress and displacement field are output.

[0056] It is necessary to supplement that the static force balance calculation adopts the existing calculation algorithm, which will not be shown, and the preset value of the stress fluctuation of the pile-soil contact interface is based on the model accuracy requirement and engineering experience setting. The stress is usually composed of normal stress and tangential stress. Exemplarily, for soft soil, the normal stress fluctuation preset value is usually in the range of less than or equal to 5 kPa, and for hard soil, the normal stress fluctuation preset value is usually in the range of less than or equal to 10 kPa. Exemplarily, for clay, the tangential stress fluctuation preset value is usually in the range of less than or equal to 2 kPa, and for sand, the tangential stress fluctuation preset value is usually in the range of less than or equal to 5 kPa. And a relative threshold value can also be used, such as the fluctuation preset value can be less than or equal to 1% of the previous step stress value, to avoid the failure of the absolute threshold value in the low stress area.

[0057] S3-2, based on the horizontal thrust and overturning moment loaded on the pile top reference point in time sequence, the wind load time history acting on the pile top reference point is generated, and based on the wave load loaded at different depths of the pile body in time sequence, the wave load time history of each node of the pile body is generated.

[0058] Understandably, the specific generation of wind load needs to combine statics theory formula when the overturning moment is dominant, and needs to combine direct mapping formula based on load transfer when the horizontal thrust directly reflects the horizontal component of wind load. When not belonging to these two cases, take the weighted average value of the two, and the weight is distributed according to the sensor accuracy, such as the weight is 0.7 when the moment sensor accuracy is higher.

[0059] S3-3, load the wind load time history to the pile top and the wave load time history to the pile body node, real-time monitor the friction force of the pile-soil contact interface, and output the pile top horizontal displacement time history curve.

[0060] S3-4, extract the common time points of the overturning moment time history and the pile top displacement time history, form the displacement-moment data pair and draw the displacement-overturning moment curve.

[0061] S3-5, identify the critical overturning state in the displacement-overturning moment curve, extract the equivalent bending stiffness of the pile body, the comprehensive shear strength parameters of the soil around the pile and the characteristic length in this state.

[0062] It is necessary to supplement that under the critical overturning state, the deformation of the pile body is concentrated near the rotating hinge, at this time the characteristic length is usually directly related to the geometric size of the pile body, which is commonly the pile diameter and the critical rotating depth.

[0063] Further, please refer to Figure 2 It is shown that the specific identification process of the critical overturning state is as follows: after smoothing the displacement-overturning moment curve, the complete data point set is derived.

[0064] The data point with a slope change amplitude exceeding a preset threshold or a concave-convex transition is marked as a potential inflection point, and the state of the potential inflection point that meets the following conditions is recorded as a critical overturning state: the pile-soil interface friction reaches the maximum shear strength of the soil.

[0065] The finite element strain cloud of the pile body shows plastic strain and the plastic zone of the soil expands from the surface layer around the pile to the depth.

[0066] The ratio of the unit moment increment to the displacement increment first exceeds the threshold value in the initial elastic stage, and the ratio of the displacement value to the overturning moment exceeds the preset threshold value of the initial decrease amplitude and continuously decreases subsequently.

[0067] Understandably, the slope change amplitude refers to the change amplitude of the slope of the line connecting the data point and the previous data point relative to the slope of the line connecting the previous adjacent data points. The preset threshold value of the slope change amplitude needs to be calibrated in combination with the type of pile body, engineering specifications and historical data. For example, for rigid piles, the slope change sensitivity threshold value is usually set to 20%-30% to avoid misjudgment of local disturbance of the soil, because the soil constraint dominates the stress. For flexible piles, the threshold value is slightly lower at 15%-25% to capture the yield signal of the pile body material earlier, and the slope change range of the known critical inflection point in similar projects can also be referred to for specific numerical determination.

[0068] Understandably, the unit moment increment refers to the change amount of the moment on the pile body at adjacent monitoring times, and the displacement increment refers to the change amount of the displacement of the pile body at adjacent monitoring times. The initial elastic stage threshold value is set based on the displacement acceleration effect principle of the pile-soil system instability. In the elastic stage, the displacement increment is approximately linearly proportional to the moment increment. When the system approaches the overturning critical point, the displacement increment caused by the same moment increment will be significantly amplified due to the expansion of the soil plastic zone and the formation of the pile body plastic hinge. The threshold value is calibrated through typical working condition finite element parameterized analysis.

[0069] Illustratively, the pile foundation model in clay, sand and silt is subjected to an increasing wind wave load, and the displacement growth rate is statistically found to increase by a multiple of 2.5-4 times when the ratio of the unit moment increment to the displacement increment first reaches 2.5-4 times the ratio in the elastic stage, and 90% of the working conditions fall into this interval. Therefore, the preset threshold value can be set to 3 times as an engineering experience value balancing safety and sensitivity.

[0070] Understandably, the preset threshold value of the decrease amplitude is set according to the stiffness degradation mechanism of the pile-soil system, and the ratio of the displacement value to the overturning moment at the effective inflection point is defined as the secant stiffness. The threshold value can be verified by indoor model test and field monitoring data.

[0071] For example, comparing the static load test data of offshore wind turbine pile foundations, when the secant stiffness decreases by 40% to 60% from the initial value, the irreversible displacement rate of the pile top exceeds 70%, and the penetration depth of the soil plastic zone reaches more than 5 times the pile diameter, which indicates the ultimate bearing capacity state. Therefore, a preset threshold of 50% can be set for the decrease.

[0072] S3-6. Based on soil layer parameters, match soil layer type, call the stiffness coefficient calculation algorithm of the corresponding soil layer type in the calculation database, and then combine the equivalent bending stiffness, comprehensive shear strength parameters and characteristic length to output the dimensionless stiffness coefficient.

[0073] Specifically, soil types can include soft clay, hard clay, dense sand, and loose sand. Soil type matching requires combining physical properties and mechanical parameters with reference to geotechnical engineering investigation specifications and empirical thresholds, forming a multi-indicator collaborative judgment system for matching.

[0074] The computational database can be based on theoretical derivation, empirical formulas, or a large number of numerical analyses to calibrate and match stiffness coefficient calculation algorithms for different soil types, and then organize and summarize them. For example, the API p-y curve correction algorithm is used for clay, and the Reese-Briaud model is used for sand. Then, the equivalent bending stiffness of the pile, the comprehensive shear strength parameters of the soil, and the characteristic length are imported to output the dimensionless stiffness coefficient.

[0075] Specifically, the specific identification process for the pile type is as follows: if the stiffness coefficient is greater than or equal to a preset first stiffness coefficient threshold and the length-to-diameter ratio is less than or equal to a preset first length-to-diameter ratio threshold, the pile type is marked as a rigid pile.

[0076] If the stiffness coefficient is less than the preset second stiffness coefficient threshold and the length-to-diameter ratio is greater than the second length-to-diameter ratio threshold, the pile type is marked as a flexible pile.

[0077] If the stiffness coefficient is greater than or equal to the preset second stiffness coefficient threshold and less than the first stiffness coefficient threshold, and the length-to-diameter ratio is greater than the preset first length-to-diameter ratio threshold and less than or equal to the second length-to-diameter ratio threshold, then the pile type is marked as a rigid-flexible pile.

[0078] It should be added that the specific identification process for the pile type is as follows: Figure 3 As shown, Figure 3 In the equation, K corresponds to the stiffness coefficient, L / D corresponds to the length-to-diameter ratio, K1 and K2 correspond to the preset first stiffness coefficient threshold and the preset second stiffness coefficient threshold, respectively, and H1 and H2 correspond to the preset first length-to-diameter ratio threshold and the preset second length-to-diameter ratio threshold, respectively.

[0079] The above thresholds can be calibrated based on typical engineering experience and numerical simulation. Recommended threshold values ​​are: K1 = 2.0, K2 = 0.5, H1 = 8, and H2 = 25. These values ​​are derived from statistical analysis of static load test data for pile foundations in clay and sand. For example, the upper limit of the 95% confidence interval for the boundary between rigid piles and rigid-flexible piles corresponds to K1 = 2.0. These values ​​have been verified through parametric simulations using the finite element model in diameters of 2-8 meters and aspect ratios of 3-40, ensuring the consistency between the pile classification results and subsequent... Figure 8 , Figure 9 The displacement patterns shown are consistent. For example, piles with a diameter ≥ 6 meters and an aspect ratio ≥ 20 are correctly identified as rigid piles because of their stiffness coefficient K > 2.0. At the same time, the complete behavior of small-diameter piles transitioning from flexible to rigid as the aspect ratio decreases is also covered.

[0080] In one specific embodiment, the different stiffness of the pile is reflected in different length-to-diameter ratios. Taking clay and sand as examples, the pile displacement simulation of horizontal deformation failure is carried out in the finite element model for different diameters, different length-to-diameter ratios, and different clay body parameters. The diameters are set to 2 meters, 4 meters, 6 meters, and 8 meters.

[0081] Clay simulation results are as follows Figure 8 As shown, Figure 8 Figures (a), (b), (c), and (d) show the pile displacement curves for diameters of 2 meters, 4 meters, 6 meters, and 8 meters, respectively. In the figures, y represents the y-axis direction, and z represents the z-axis, i.e., the depth direction.

[0082] according to Figure 8 As shown in Figure (a), when the diameter is 2 meters, the displacement curve is significantly curved when the L / D ratio is large, such as 20, 30, and 40. The upper and middle parts of the pile body are significantly deformed, exhibiting typical characteristics of a flexible pile. Its deformation is mainly dominated by the bending of the pile body. When the L / D ratio decreases, the curvature of the curve decreases, and it gradually shows a trend of overall rotation, indicating that the behavior of the pile begins to transition from flexible to semi-rigid.

[0083] according to Figure 8 As shown in (b), when the diameter is 4 meters, the curve with a larger L / D still exhibits a curved shape, but compared to the pile with D=2m, its degree of curvature is reduced at the same L / D. The curve with a smaller L / D is closer to a straight line, indicating that for a pile with a diameter of 4m, a clear rigid pile rotation characteristic can be exhibited at a smaller L / D.

[0084] According to Figure 8 (c) and Figure 8As shown in Figs. (d), for large diameter piles, even when L / D reaches 20 or more, the displacement curves are still relatively straight, and the bending shape is not significant. That is, large diameter piles can exhibit rigid behavior at a smaller L / D value due to their large self-stiffness, and their behavior mode is mainly overall rotation.

[0085] and in combination Figure 8 It can be seen that when L / D is large, such as 20, 30, 40, the displacement curves of all pile diameters exhibit significant bending shape. The displacement is maximum at the top of the pile (z / L=0), and rapidly decays with depth, and approaches zero at a certain depth (z / L is about 0.6-0.8). When L / D is small, such as 3, 7, the displacement curve is very close to a straight line. From the top of the pile to the bottom of the pile, the displacement decreases linearly, and the displacement at the bottom of the pile (z / L=1.0) is not zero or even negative, which is a typical sign of rigid rotation of the pile. When L / D is in the middle range, such as 9, 12, 14, the displacement curve shape is between the above two. There is a significant bending component, and there is also a tendency of overall rotation, which is the transition zone of the behavior mode.

[0086] In summary, under the same clay soil and the same pile diameter, reducing the length-diameter ratio is a direct and decisive factor leading to the transition of the pile from flexible behavior to rigid behavior. At the same time, increasing the pile diameter can significantly improve the bending stiffness of the pile, which makes large diameter piles exhibit rigid pile characteristics at a smaller L / D value.

[0087] The sand simulation results are shown in Figure 9 , wherein Figure 9 Figs. (a), (b), (c) and (d) respectively represent the pile displacement curve diagrams when the diameters are 2 meters, 4 meters, 6 meters and 8 meters.

[0088] According to Figure 9 Fig. (a), when the diameter is 2 meters, when L / D is large, such as 20, 30, 40, the curve is obviously bent, the upper part of the pile body is deformed, and the typical flexible pile characteristics are exhibited. When L / D is small, such as 3, 7, the curve is closer to a straight line, indicating rigid rotation.

[0089] According to Figure 9 Fig. (b), when the diameter is 4 meters, the curve is still bent when L / D is large, but the curve is straight when L / D is small, indicating that larger diameter piles can exhibit rigid behavior at a smaller L / D.

[0090] According to Figure 9 Figs. (c) and Figure 9 Fig. (d), when the diameters are 6 meters and 8 meters, even when L / D reaches 20, the curve is still relatively straight, indicating that large diameter piles are more likely to exhibit rigid characteristics.

[0091] and in combinationFigure 9 It can be observed that when L / D is large, such as 20, 30, and 40, the displacement curves for all pile diameters exhibit a significant bending shape. The displacement is maximum at the pile top and decreases rapidly with increasing depth, approaching zero at a certain depth (z / L approximately 0.6-0.8). When L / D is small, such as 3 and 7, the displacement curves are very close to a straight line. From the pile top to the pile bottom, the displacement decreases linearly. At the pile bottom (z / L=1.0), the displacement is not zero or even negative. When L / D is in the middle range, such as 9, 12, and 14, the displacement curve shape is between the two extremes, exhibiting both a clear bending component and a tendency for overall rotation.

[0092] In summary, under the same sandy soil conditions and pile diameter, reducing the length-to-diameter ratio is the direct and decisive factor that causes the pile to transition from flexible to rigid behavior. Increasing the pile diameter will significantly improve the bending stiffness of the pile, which allows large-diameter piles to exhibit the characteristics of rigid piles earlier at a larger L / D value.

[0093] Based on finite element analysis of pile failure displacements under different pile diameters, length-to-diameter ratios, and soil types, the following conclusion can be drawn: as the length-to-diameter ratio of the pile decreases, steel pipe piles transition from flexible piles to rigid-flexible piles and then to rigid piles. Flexible piles are characterized by bottom embedment and upper deformation, while rigid piles experience rotational failure. Rigid-flexible piles, falling between flexible and rigid piles, exhibit a combination of shallow flexible deformation and deep rigid rotation.

[0094] It should be noted that the above combination Figure 8 and Figure 9 The description of the pile's behavior pattern is an intuitive summary and regular display of the pile's displacement morphology based on finite element simulation results, aiming to facilitate the understanding of the physical phenomena revealed by this invention.

[0095] In practical implementation, the above-mentioned logical rule for determining pile type by jointly using stiffness coefficient and aspect ratio threshold is... Figure 8 and Figure 9 The mathematical generalization and quantitative expression of the experimental laws shown demonstrate that for small-diameter piles such as D=2 meters, their stiffness coefficient is relatively low, and their behavior is mainly controlled by the length-to-diameter ratio. Therefore, they exhibit a clear law that transitions to rigidity as L / D decreases. For large-diameter piles such as D=8 meters, their extremely high stiffness coefficient (K>K1) means that even under typical conditions where L / D≤H1 is not satisfied (e.g., L / D=20), their enormous inherent stiffness dominates their mechanical behavior, transcending the influence of simple geometric dimensions. They are still accurately classified as rigid piles.

[0096] S4. Environmental load disturbance quantification: Combine multidimensional dataset and pile type to quantify the environmental deviation compensation coefficient.

[0097] Specifically, the quantification process of the environmental deviation compensation coefficient is as follows: extract the horizontal displacement at the top of the pile, the maximum stress of the pile body, and the maximum friction force at the pile-soil contact interface, and form a model response dataset.

[0098] The actual monitoring data is acquired synchronously by the monitoring equipment deployed on site, forming an on-site measured response dataset that matches the time series and parameter types of the model response dataset.

[0099] The model and the measured response dataset were compared to identify parameters and time periods where the deviation exceeded the standard.

[0100] The source of the deviation is determined by considering the parameters exceeding the standard, the time period of the deviation, and in combination with wave spectrum parameters, wind distribution data, and tidal parameters.

[0101] Based on the pile type and the source of deviation, a preset associated compensation process is matched, and the final environmental deviation compensation coefficient is output after hierarchical quantification based on the process.

[0102] It should be added that if the horizontal displacement of the pile top exceeds the standard during periods when the wind speed exceeds 1.2 times the design value, and the deviation direction is consistent with the wind direction, the source of the deviation is determined to be wind load dominant. If the stress in the middle and lower part of the pile exceeds the standard during periods when the wave height exceeds 2m, and the fluctuation period matches the wave period, the source of the deviation is determined to be wave load dominant. If the displacement of the underwater section of the pile exceeds the standard during periods of sudden changes in tidal water level, such as changes exceeding 1.5m within 1 hour, and is synchronized with the rise and fall of the water level, the source of the deviation is determined to be tidal dominant.

[0103] It is important to note that specific values ​​such as wind speed exceeding the design value by 1.2 times, wave height exceeding 2m, and tidal hourly variation exceeding 1.5m are derived from the correlation calibration between engineering design parameters and environmental load characteristics. Specifically, the 1.2 times wind speed threshold corresponds to the gust load effect amplification factor in the specifications and is matched with the upper limit of short-term fluctuations in design wind speed. The 2m wave height is obtained by referring to the port engineering load specifications for the sea area where the project is located. The 1.5m tidal variation is taken as 1.2 times the historical maximum hourly variation from the tidal table at the project location, ensuring coverage of extreme water level fluctuations. All values ​​have been verified through back-calculation using similar engineering deviation cases.

[0104] Understandably, if the pile type is a rigid pile and the source of deviation is wave load, the wave force coefficient graded adjustment process is activated; if the pile type is a flexible pile and the source of deviation is wind load, the wind load shape coefficient correction process is activated; if the pile type is a rigid-flexible pile and the source of deviation includes tides, the tidal level and moment point of application linkage compensation process is activated.

[0105] Further, the deviation degree is classified into levels for the selected compensation process. For example, slight deviation is 15%-25%, moderate deviation is 25%-40%, and severe deviation is greater than 40%. According to the adjustment rules corresponding to each level in the preset process, for example, the coefficient is fine-tuned by 5%-10% for slight deviation, 10%-20% for moderate deviation, and 20%-30% for severe deviation, combined with the sensitive characteristics of the pile type to the load, for example, the adjustment range of the wave load coefficient of the rigid pile is higher than that of the wind load, to determine the specific compensation coefficient value, and the quantized environmental deviation compensation coefficient is stored in association with the pile type, the deviation source, and the deviation level, forming an environmental deviation compensation coefficient table containing applicable scene description.

[0106] For example, the wind load deviation can be classified into low, medium, and high compensation levels according to the wind speed interval, such as less than or equal to 10 m / s, 10-25 m / s, and greater than 25 m / s.

[0107] S5, bearing capacity calculation and determination: calculate the preliminary horizontal bearing capacity according to the pile type, judge whether the bearing capacity failure critical state is reached based on the pile displacement data in the current monitoring period, if the critical state is reached, set the displacement deviation compensation coefficient, and output the final horizontal bearing capacity by modifying the preliminary horizontal bearing capacity with the environmental deviation compensation coefficient and the displacement deviation compensation coefficient.

[0108] Specifically, the specific calculation process of the preliminary horizontal bearing capacity is as follows: according to the pile type, extract the required parameters for the main force from the three-dimensional pile-soil model, and match the horizontal bearing capacity calculation rules corresponding to the pile state type.

[0109] Calculate the preliminary horizontal bearing capacity according to the matched calculation rules based on the parameters, and iteratively calculate the preliminary horizontal bearing capacity until the difference between the preliminary horizontal bearing capacity and the model displacement-load curve inflection point value exceeds the engineering allowable threshold.

[0110] Understandably, for the rigid pile, the required parameters for the main force are the maximum resistance distribution of the soil around the pile, the maximum shear capacity of the pile-soil contact interface, and the load value when the horizontal displacement at the top of the pile reaches the specification limit, and the soil constraint dominant calculation rule is matched.

[0111] For example, according to the maximum resistance distribution of the soil around the pile, the total force of the passive earth pressure in front of the pile is calculated, such as the total resistance within 3 times the pile diameter range below the ground surface, and the lateral constraint bearing capacity provided by the soil is obtained by multiplying the ratio of the pile length to the pile diameter, and it is verified whether the maximum shear capacity of the pile-soil contact interface is greater than or equal to 1.2 times the lateral constraint bearing capacity. If it is satisfied, the minimum value of the load value when the horizontal displacement at the top of the pile reaches the specification limit and the lateral constraint bearing capacity of the soil is taken as the preliminary horizontal bearing capacity of the rigid pile.

[0112] Understandably, the parameters required for the dominant stress of the rigid-flexible pile are the maximum reaction force of the soil around the pile, the ultimate stress of the pile material, the displacement limit load, and the maximum shear capacity of the contact interface, and the matching synergistic stress calculation rules.

[0113] Illustratively, the pile's own bending resistance is calculated according to the ultimate stress of the pile material combined with the cross-sectional size of the pile body, the lateral restraint capacity of the soil and the pile's own bending resistance are summed by weighting to obtain the synergistic capacity, and it is verified whether the shear capacity of the contact interface is greater than or equal to 1.1 times the synergistic capacity. If the smaller value of the synergistic capacity and the displacement limit load is taken as the preliminary horizontal bearing capacity of the rigid-flexible pile.

[0114] Understandably, the parameters required for the dominant stress of the flexible pile are the ultimate stress of the pile material, the displacement limit load, and the maximum reaction force of the soil around the pile, and the matching calculation rules of the pile strength.

[0115] Illustratively, the horizontal thrust corresponding to the maximum bending moment of the pile body is calculated according to the ultimate stress of the pile material, i.e. the bending resistance of the pile body, and it is verified whether the maximum reaction force of the soil around the pile is greater than or equal to 0.3 times the horizontal thrust. If the smaller value of the bending resistance of the pile body and the displacement limit load is taken as the preliminary horizontal bearing capacity of the flexible pile.

[0116] In one specific embodiment, the values of the above-mentioned values are determined comprehensively based on theoretical basis, industry standards and engineering experience, etc. For example, 3 times the pile diameter is derived from the significant stress influence range of the soil around the pile in soil mechanics, which is usually 3-5 times the pile diameter. The shear capacity verification coefficients of 1.2 times and 1.1 times are based on the structural safety reserve. The experience verification coefficient of 0.3 times is for the flexible pile when the soil constraint is weak. The specification limit of the displacement limit load refers to the horizontal displacement control standard in the Pile Foundation Technical Specification. The engineering allowable threshold is determined by combining the calculation accuracy requirement and the statistical deviation of similar engineering measurements.

[0117] Further, the iterative calculation process includes: comparing the preliminary bearing capacity with the inflection point value of the model displacement-load curve, and if the difference exceeds the preset engineering allowable threshold, outputting the preliminary bearing capacity.

[0118] Otherwise, based on the type of the pile body, the correction index is matched and the preliminary horizontal bearing capacity is calculated based on the corrected index according to the calculation rules, and the comparison and correction calculation are repeated until the difference exceeds the preset engineering allowable threshold, and the final preliminary horizontal bearing capacity is output.

[0119] Exemplarily, the rigidity pile correction index is the passive earth pressure coefficient of the soil around the pile. The rigidity-flexibility pile correction index is the weighted coefficient of the lateral constraint bearing capacity of the soil and the bending resistance bearing capacity of the pile body, such as adjusting the soil constraint proportion from 0.4 to 0.5, with 0.5 as the upper limit. The flexibility pile correction index is the maximum reduction coefficient of the reaction force of the soil around the pile, such as adjusting from 0.3 to 0.32.

[0120] Still another specifically, please refer to Figure 4 As shown in the figure, the judging whether the bearing capacity failure critical state is reached includes: pre-processing the current period displacement monitoring data, extracting the real-time displacement value and statistically analyzing the displacement rate, acceleration, fluctuation amplitude and cumulative trend slope to form the current displacement control index set.

[0121] The core displacement control index, auxiliary displacement control index and threshold corresponding to the pile body type are extracted from the pile foundation engineering design table.

[0122] The current core and auxiliary displacement control index corresponding to the pile body type are matched from the current displacement control index set.

[0123] If the current core displacement control index exceeds the corresponding threshold, the auxiliary displacement control index is compared with the corresponding threshold.

[0124] If there are multiple auxiliary displacement control indexes exceeding the limit, it is judged that the failure critical state is reached, otherwise it is judged that it is not reached.

[0125] It needs to be supplemented that the pre-processing includes but is not limited to sliding filtering to remove abnormal values, and the displacement rate is the ratio of the displacement change amount in the current period to the period length, the displacement acceleration can be obtained by statistically analyzing the ratio of the rate difference value of the continuous two periods to the period length, the displacement fluctuation amplitude in the period is the difference between the maximum displacement and the minimum displacement in the current period, and the cumulative displacement trend slope can be obtained by linear fitting the displacement data of the current period and the previous several periods, such as 3 periods, wherein the positive slope is continuous growth and the negative slope is convergence.

[0126] It also needs to be supplemented that the pile foundation engineering design table is obtained based on the pile foundation type, stress characteristics, displacement control standard and the like.

[0127] Exemplarily, the core displacement control index of the rigidity pile is the real-time displacement value and the cumulative trend slope, the auxiliary index is the displacement rate and the fluctuation amplitude, the core displacement control index of the rigidity-flexibility pile is the real-time displacement value and the displacement rate, the auxiliary index is the acceleration and the cumulative trend slope, and the core displacement control index of the flexibility pile is the displacement rate and the acceleration, and the auxiliary index is the real-time displacement value and the fluctuation amplitude.

[0128] Further, the specific setting process of the displacement deviation compensation coefficient is as follows: record the categories and exceeding degrees of all core indexes and auxiliary indexes exceeding the threshold value to form an over-limit index list.

[0129] The over-limit index list is matched with the preset displacement deviation compensation coefficient associated over-limit index list, and the matched displacement deviation compensation coefficient is output.

[0130] It should be noted that the preset displacement deviation compensation coefficient associated over-limit index list can be based on historical engineering data statistics, environmental load and deviation correlation analysis and specification threshold calibration. Specifically, a large number of model responses and field measured data of the same type of engineering are collected to extract historical over-limit indexes, such as pile top displacement exceeding 10mm, pile body stress exceeding 20% design value, and corresponding deviation sources. The historical data are classified and counted according to the over-limit index type, deviation source and compensation coefficient effect, and the correlation such as pile top horizontal displacement over-limit and wind load dominant corresponding compensation coefficient 0.8, pile body stress over-limit and tide dominant corresponding compensation coefficient 0.9 is determined. Combined with the displacement deviation limit value caused by wave load in the allowable range of deviation under the action of environmental load in the specification, the preset correlation list covering various over-limit indexes and deviation sources is finally formed.

[0131] Further, the above correction method is to calculate the environmental deviation compensation coefficient and the linear weighted sum of the environmental deviation compensation coefficient to obtain a comprehensive correction coefficient. The sum of the comprehensive correction coefficient and 1 is multiplied by the preliminary horizontal bearing capacity to obtain the modified final horizontal bearing capacity. If the modified horizontal bearing capacity is closer to the field measured value or the model verification value, the modified horizontal bearing capacity is output, and the collaborative compensation of the environment and the displacement deviation is realized.

[0132] Understandably, the weight setting is based on the sensitivity of the pile type to the two types of deviation, for example, the rigid pile is more affected by the environmental load, the environmental deviation compensation coefficient weight is 0.6, and the displacement deviation compensation coefficient weight is 0.4. The flexible pile is more significantly affected by the displacement related deviation, the environmental deviation compensation coefficient weight is 0.4, and the displacement deviation compensation coefficient weight is 0.6. The rigid and flexible pile adopts balanced weight of 0.5, balancing the comprehensive influence of the two types of deviation.

[0133] The embodiment of the present application compares the model response data with the field measured data, locates the deviation period and associates the environmental load characteristics, quantifies the environmental deviation compensation coefficient according to the pile type classification, and then real-time corrects the difference between the model and the actual environmental load, so as to ensure that the calculation result adapts to the dynamic changes of complex marine working conditions. At the same time, through the double coefficient correction of the environmental deviation compensation coefficient and the displacement deviation compensation coefficient, the accuracy of the calculation result is ensured.

[0134] The above merely illustrates and describes the concept of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or adopt similar ways to replace, as long as the modifications or supplements do not deviate from the concept of the present application or exceed the defined scope of the present application, and should belong to the protection scope of the present application.

Claims

1. A method for accurately calculating the horizontal bearing capacity of offshore wind turbine foundations, characterized in that, The method includes: S1. Multi-source environmental data integration: Collect wave spectrum parameters, wind distribution data, tidal parameters and soil stratification parameters within the current monitoring period and integrate them into a multidimensional dataset; S2. Multi-scale coupling model construction: Establish a three-dimensional pile-soil model and couple wave force and wind load to the pile body; S3. Dynamic classification of pile stiffness: The stiffness coefficient is calculated based on the three-dimensional pile-soil model, and the pile type is identified according to the correspondence between the coefficient and the length-to-diameter ratio. The pile type is one of rigid pile, rigid-flexible pile and flexible pile. S4. Environmental Load Disturbance Quantification: Combining multidimensional datasets and pile type, the environmental deviation compensation coefficient is quantified. The specific quantification process is as follows: Extract the horizontal displacement at the pile top, the maximum stress in the pile body, and the maximum frictional force at the pile-soil interface, and combine them to form a model response dataset. The actual monitoring data is acquired synchronously by the monitoring equipment deployed on site, forming an on-site measured response dataset that matches the time series and parameter types of the model response dataset. Compare the model and the measured response dataset to identify parameters and time periods where the deviation exceeds the standard. The source of deviation is determined based on the parameters exceeding the standard, the time period of deviation, and in combination with wave spectrum parameters, wind distribution data, and tidal parameters. Based on the pile type and the source of deviation, a preset associated compensation process is matched, and the final environmental deviation compensation coefficient is output after hierarchical quantification based on the process. S5. Bearing capacity calculation and determination: Calculate the preliminary horizontal bearing capacity according to the pile type, determine whether the bearing capacity failure critical state has been reached based on the pile displacement data of the current monitoring period, if the critical state has been reached, set the displacement deviation compensation coefficient, and output the final horizontal bearing capacity after correcting the preliminary horizontal bearing capacity through the environmental deviation compensation coefficient and the displacement deviation compensation coefficient. The specific calculation process for the preliminary horizontal bearing capacity is as follows: Based on the pile type, extract the parameters required for the main force from the three-dimensional pile-soil model, and at the same time match the horizontal bearing capacity calculation rules corresponding to the pile state type. Based on the parameters, the preliminary horizontal bearing capacity is calculated according to the matching calculation rules. The preliminary horizontal bearing capacity is iteratively calculated until the difference between it and the inflection point value of the model displacement-load curve exceeds the engineering allowable threshold. The specific process for setting the displacement deviation compensation coefficient is as follows: Record the categories and degrees of exceedance of all core and auxiliary indicators that exceed the threshold, and compile a list of indicators exceeding the limit; The list of out-of-limit indicators is matched and compared with the preset displacement deviation compensation coefficients, and then the matched displacement deviation compensation coefficients are output.

2. The method for accurately calculating the horizontal bearing capacity of offshore wind power foundations as described in claim 1, characterized in that: The specific execution process of step S1 is as follows: Wave monitoring buoys are deployed in the sea area where wind power facilities are located. The instantaneous amplitude, period and propagation direction of waves are collected by the wave monitoring buoys to generate wave spectra. Instantaneous wind speed and direction at different altitudes are collected by meteorological monitoring stations, wind speed profiles are generated hourly, and gust characteristics are identified to obtain wind condition distribution data. Tidal parameters are obtained by recording tidal changes through tide gauge stations or water level sensors, extracting the time of rising and falling tides, tidal range, and the times of high and low tides. The mechanical parameters of the soil around the pile are obtained by static cone penetration or vane shear test, and the soil stratification parameters are obtained by combining borehole sampling to determine the soil stratification boundaries and physical properties. Align the peak times of wave spectrum energy, wind speed profile, and high and low tide levels with timestamps. All data are integrated into a three-dimensional structure based on time, space, and parameter type to generate the multidimensional dataset.

3. The method for accurately calculating the horizontal bearing capacity of offshore wind power foundations as described in claim 1, characterized in that: The specific execution process of step S2 is as follows: A three-dimensional pile-soil model is constructed in finite element software based on the pile's geometric parameters. Based on wave spectrum data, the horizontal impact force and vertical buoyancy of waves on the pile are calculated using fluid dynamics equations, and then converted into wave loads at different depths of the pile and loaded into the model in a time series. The horizontal thrust and overturning moment at the pile top are calculated based on wind distribution data. The horizontal thrust is applied according to the wind direction and time sequence with the geometric center of the pile top as the reference point, and the overturning moment is applied synchronously along the rotation direction.

4. The method for accurately calculating the horizontal bearing capacity of offshore wind turbine foundations as described in claim 3, characterized in that: The specific calculation process for the stiffness coefficient is as follows: Apply self-weight load to the three-dimensional pile-soil model to perform static equilibrium calculations until the stress fluctuation at the pile-soil interface is less than the preset value, and then output the initial stress and displacement field. The wind load time history acting on the pile top reference point is generated based on the horizontal thrust and overturning moment loaded at the pile top reference point according to the time series. At the same time, the wave load time history of each node of the pile body is generated based on the wave load at different depths of the pile body loaded according to the time series. The wind load time history is applied to the pile top and the wave load time history is applied to the pile body nodes. The friction force at the pile-soil contact interface is monitored in real time, and the time history curve of the horizontal displacement at the pile top is output. Extract the common time points of the overturning moment time history and the pile top displacement time history to form a displacement-moment data pair and plot the displacement-overturning moment curve; Identify the critical overturning state in the displacement-overturning moment curve, and extract the equivalent bending stiffness of the pile, the comprehensive shear strength parameters of the soil around the pile, and the characteristic length under this state. Based on soil layer parameters matching soil layer type, the algorithm for calculating the stiffness coefficient of the corresponding soil layer type in the calculation database is called, and then combined with the equivalent bending stiffness, comprehensive shear strength parameters and characteristic length to output the dimensionless stiffness coefficient.

5. The method for accurately calculating the horizontal bearing capacity of offshore wind turbine foundations as described in claim 4, characterized in that: The specific identification process for the critical overturning state is as follows: After smoothing the displacement-overturning moment curve, the complete data point set is exported. Data points whose slope changes exceed a preset threshold or whose convexity changes are identified as potential inflection points. Potential inflection points that simultaneously meet the following conditions are designated as critical overturning states: The frictional force at the pile-soil contact surface reaches the maximum shear strength of the soil. The finite element strain cloud map of the pile shows plastic strain and that the plastic zone of the soil extends from the surface around the pile to the depth. The ratio of unit torque increment to displacement increment exceeds the initial elastic stage threshold for the first time, and the ratio of displacement value to overturning moment decreases by more than the preset threshold and continues to decrease thereafter.

6. The method for accurately calculating the horizontal bearing capacity of offshore wind power foundations as described in claim 1, characterized in that: The specific identification process for the pile type is as follows: If the stiffness coefficient is greater than or equal to the preset first stiffness coefficient threshold and the length-to-diameter ratio is less than or equal to the preset first length-to-diameter ratio threshold, the pile type is marked as a rigid pile. If the stiffness coefficient is less than the preset second stiffness coefficient threshold and the length-to-diameter ratio is greater than the second length-to-diameter ratio threshold, the pile type is marked as a flexible pile. If the stiffness coefficient is greater than or equal to the preset second stiffness coefficient threshold and less than the first stiffness coefficient threshold, and the length-to-diameter ratio is greater than the preset first length-to-diameter ratio threshold and less than or equal to the second length-to-diameter ratio threshold, then the pile type is marked as a rigid-flexible pile.

7. The method for accurately calculating the horizontal bearing capacity of offshore wind power foundations as described in claim 1, characterized in that: The determination of whether the critical state of bearing capacity failure has been reached includes: Preprocess the current period displacement monitoring data, extract real-time displacement values, and statistically analyze displacement rate, acceleration, fluctuation amplitude, and cumulative trend slope to form the current displacement control index set; Extract the core displacement control indicators, auxiliary displacement control indicators, and thresholds corresponding to the pile type from the pile foundation engineering design table; Match the current core and auxiliary displacement control indicators corresponding to the pile type from the current displacement control indicator set; If the current core displacement control index exceeds the corresponding threshold, compare each auxiliary displacement control index with the corresponding threshold. If multiple auxiliary displacement control indicators exceed the limits, it is determined that the critical failure state has been reached; otherwise, it is determined that it has not been reached.

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