A scour duration prediction method for wind power pile foundation considering space-time effect

Abstract

The present application relates to the offshore wind power engineering field, disclose a kind of considering time-space effect's wind power pile foundation scour duration prediction method, comprising: obtaining target sea area environmental parameter and pile foundation basic parameter, calculate hydrodynamics parameter and limit equilibrium scour depth;According to the law of conservation of sediment volume and space net flux, a time-space evolution model is established;Using historical scour measured data to calibrate the undetermined coefficient in the model;Based on the calibrated model, the characteristic time scale is calculated, and the duration prediction chart of the continuous change of scour depth with time is output;The final scour depth at the end of service is compared with the safety depth threshold determined according to the stress state, and the early warning is output.The present application establishes an evolution model by combining the physical mechanism of sediment and calibrates the parameters using in-situ measured data, which improves the rigor and accuracy of the prediction, and also relates to the actual anti-overturning index of pile foundation, providing quantitative engineering basis for the structural safety evaluation and protection design of offshore wind farm.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power engineering technology, specifically to a method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects. Background Technology

[0002] Offshore wind turbine foundations are susceptible to localized scouring of the seabed under the combined action of waves and currents. Scouring reduces the depth of the foundation penetration, lowers its bearing capacity and overturning stability, and consequently affects the operational safety of the wind turbine. Therefore, accurately predicting the scouring depth around the foundation and its dynamic development over time is an engineering requirement for the structural design and subsequent operation and maintenance of offshore wind farms.

[0003] Existing methods for predicting wind turbine pile scour primarily focus on calculating the ultimate equilibrium scour depth, i.e., estimating the final depth after scour reaches a steady state. These conventional methods often neglect the spatiotemporal evolution of scour depth in practical applications, failing to provide a dynamic accumulation process of continuous change in scour depth over the wind farm's service life. Some research methods involving scour duration largely rely on direct curve fitting of flume test data, failing to deeply integrate physical mechanisms such as sediment mass conservation and net spatial flux to establish a mathematical correlation between temporal and spatial characteristics. This leads to predictive biases in computational models when faced with complex marine hydrodynamic conditions.

[0004] Meanwhile, existing theoretical models typically use predetermined empirical constants for empirical parameters, failing to effectively integrate historical measured scour data from the target sea area for in-situ calibration and parameter correction. This reduces the model's predictive adaptability within specific engineering geological regions. Furthermore, current scour duration predictions largely remain at the level of single-depth numerical calculations, rarely integrating the prediction results with actual overturning safety indicators such as the superstructure loads faced by wind turbine foundations and the mechanical parameters of the surrounding soil. This fragmented approach makes it difficult for prediction models to directly assess exceeding limits, failing to provide quantitative early warning and guidance for the design dimensions of engineering scour protection structures. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for predicting the scour duration of wind turbine pile foundations that considers spatiotemporal effects. This method solves the problems that existing offshore wind turbine pile foundation scour prediction methods cannot combine sediment physical mechanisms with measured data to dynamically predict the evolution of scour depth over time, and are difficult to correlate with the actual stress state of the project for scour prevention and safety early warning.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of the present invention provides a method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects, comprising:

[0007] Obtain environmental parameters of the target sea area and foundation parameters of the target wind turbine pile foundation; Calculate the hydrodynamic parameters of the target sea area based on environmental and basic parameters; Based on hydrodynamic parameters, the ultimate equilibrium scour depth of the target wind turbine pile foundation is calculated. Based on the law of conservation of sediment volume and net spatial flux of sediment in the scour pit area around the target wind turbine foundation, a spatiotemporal evolution model is established to characterize the relationship between the scour time scale and the ultimate equilibrium scour depth. Historical scour measurement data of local wind power pile foundations were obtained, and regression fitting and calibration were performed on the undetermined coefficients in the spatiotemporal evolution model to obtain the calibrated spatiotemporal evolution model. Based on the calibrated spatiotemporal evolution model and the ultimate equilibrium scour depth, the characteristic time scale of the target wind turbine foundation is calculated, and the scour duration prediction result is output based on the characteristic time scale.

[0008] Preferably, the basic parameters include the pile diameter; the environmental parameters include the median particle size of sediment, the density ratio of sediment to water, the characteristic flow velocity of water, the kinematic viscosity coefficient of seawater, and the gravitational acceleration. Calculate the hydrodynamic parameters of the target sea area based on environmental and basic parameters, including: The Froude number, which characterizes the effect of inertial force in water flow, is calculated based on the characteristic flow velocity, gravitational acceleration, and pile diameter. The maximum bed shear stress under wave-current coupling state is calculated based on environmental parameters, and the frictional velocity of the target sea area is obtained by combining seawater density. By combining the converted frictional velocity with the density ratio of sediment to water and the median particle size of sediment, the Shield number, which characterizes the shear driving force of water flow on sediment, is calculated. The dimensionless particle size is calculated based on the median particle size of sediment, the density ratio of sediment to water, gravitational acceleration, and seawater kinematic viscosity coefficient. The critical Shield number, which characterizes the critical resistance to sediment initiation, is then calculated based on the dimensionless particle size. The calculated Froude number, Shield number, and critical Shield number are combined and used as hydrodynamic parameters.

[0009] Preferably, the ultimate equilibrium scour depth of the target wind turbine pile foundation is calculated based on hydrodynamic parameters, including: The Froude number is extracted from the hydrodynamic parameters and substituted into a preset exponential prediction formula with the Froude number as the independent variable to calculate the dimensionless scour depth ratio. The ultimate equilibrium scour depth of the target wind turbine pile foundation is calculated by multiplying the dimensionless scour depth ratio by the pile diameter.

[0010] Preferably, a spatiotemporal evolution model characterizing the relationship between the scour timescale and the ultimate equilibrium scour depth is established based on the law of conservation of sediment volume and the net spatial flux of sediment in the scour pit area surrounding the target wind turbine foundation, including: Define the rate of change of the volume of the scour pit with respect to time, and calculate the net flux of sediment outward from the scour pit area according to the law of conservation of sediment volume. By establishing an equal relationship between the rate of volume change and the net sediment flux, a correlation equation was derived showing that the rate of change of scour depth is proportional to the average sediment dispersion within the scour pit area. An exponential decay model incorporating a characteristic time scale and a limit equilibrium scour depth is introduced. The rate of change equation of the scour depth is obtained by differentiating the exponential decay model with respect to time. Substituting the equation for the rate of change of scour depth obtained by differentiation into the correlation equation, an algebraic expression for the characteristic time scale containing the average sediment divergence at the initial moment is derived. The average sediment dispersion at the initial moment under the flat bed condition is equivalently replaced by the ratio of the initial unit width sediment transport rate to the pile diameter; A bedload kinetics formula containing an empirical index of the sediment transport rate to be calibrated is introduced to represent the initial unit width sediment transport rate. The initial unit width sediment transport rate is then substituted into the characteristic time scale expression for variable substitution. A dimensionless time scale is introduced to standardize the characteristic time scale expression after variable substitution. The proportional constants generated during the conversion process are combined into a comprehensive coefficient to be calibrated. Finally, a spatiotemporal evolution model including a dimensionless time scale, limit equilibrium scour depth, empirical index of sediment transport rate, and comprehensive coefficient is established.

[0011] Preferably, historical scour measurement data of local wind turbine pile foundations are obtained, and regression fitting and calibration are performed on the undetermined coefficients in the spatiotemporal evolution model to obtain the calibrated spatiotemporal evolution model, including: Acquire historical scour measured data samples under different water flow conditions, and extract the characteristic time scale measured values, limit equilibrium scour depth measured values, water flow characteristic velocity, sample pile diameter, and sample sediment median particle size corresponding to the historical scour measured data samples. The dimensionless time scale of the corresponding sample is calculated based on the measured values ​​of the sample pile diameter, the median particle size of the sample sediment, and the characteristic time scale. The Shield number of the corresponding sample is calculated in combination with the characteristic flow velocity of the water flow. The dimensionless scour spatial scale of the corresponding sample is calculated based on the measured values ​​of the sample pile diameter and the ultimate equilibrium scour depth. The dimensionless time scale, Shields number, and dimensionless scour spatial scale corresponding to the same data sample are mapped and combined to generate a standard dimensionless data point set for fitting parameters of the spatiotemporal evolution model.

[0012] Preferably, after generating the standard dimensionless data point set for fitting the parameters of the spatiotemporal evolution model, the method further includes: By taking the natural logarithm of both sides of the equation of the spatiotemporal evolution model, a logarithmically transformed spatiotemporal evolution model is obtained. Based on the spatiotemporal evolution model after logarithmic transformation, the dependent and independent variables are defined, and the spatiotemporal evolution model is converted into a standard linear function equation composed of the dependent and independent variables. Substitute the standard dimensionless data point set into the definitional relationship between the dependent and independent variables contained in the standard linear function equation to calculate and generate the corresponding two-dimensional scattered point coordinate set. The least squares method is used to perform linear regression on a two-dimensional scattered coordinate set to obtain the slope and intercept of the optimal regression line; The specific constant values ​​of the undetermined coefficients in the spatiotemporal evolution model are calculated using the slope and intercept, and then the specific constant values ​​are substituted back into the spatiotemporal evolution model to complete the model calibration.

[0013] Preferably, the characteristic timescale of the target wind turbine foundation is calculated based on the calibrated spatiotemporal evolution model and the ultimate equilibrium scour depth, including: By substituting the Shield number and critical Shield number from the hydrodynamic parameters, along with the ultimate equilibrium scour depth, into the calibrated spatiotemporal evolution model, the dimensionless timescale prediction value under the target dynamic conditions is calculated. By constructing a conversion formula for dimensionless time scales, a reverse calculation is performed to restore the dimensionless time scale prediction value to a characteristic time scale with absolute time units.

[0014] Preferably, the output of scour duration prediction results based on characteristic time scales includes: The characteristic time scale and the ultimate equilibrium scour depth are substituted into the exponential decay model as boundary control parameters of time and space to construct a dynamic prediction model of scour history specific to the target wind power pile foundation. Input a preset time series set into the dynamic prediction model of scour history, and calculate the real-time scour depth set corresponding to each time node in the time series set through model decay calculation; Using a preset time series set as the horizontal axis and the corresponding real-time scour depth set as the vertical axis, a historical prediction chart of scour depth changing continuously over time is generated and output.

[0015] Preferably, after generating and outputting a historical prediction chart showing the continuous variation of scour depth over time, the method further includes: Extract the end-of-service time corresponding to the design service life of the wind farm from a preset time series set; The expected final scour depth at the end of service was calculated using a dynamic prediction model of scour duration. Obtain the preset safe burial depth threshold for wind turbine pile foundations. The safe burial depth threshold is pre-calculated and determined based on the upper combined load of the target wind turbine pile foundation, the mechanical parameters of the soil around the pile, and the ultimate overturning stability requirements. The expected final scour depth is compared and verified with the safe burial depth threshold. If it is determined that the expected final scour depth is greater than the safe burial depth threshold, an over-limit warning signal will be generated and the recommended protection dimensions of the scour protection bottom structure will be output. If the expected final scour depth is determined to be less than or equal to the safe burial depth threshold, a safety assessment pass signal is generated, indicating that the current design of the target wind turbine pile foundation meets the scour prevention safety requirements.

[0016] A second aspect of the present invention provides a wind turbine pile foundation scour duration prediction system considering spatiotemporal effects, used to execute a wind turbine pile foundation scour duration prediction method considering spatiotemporal effects as described in the first aspect of the present invention, comprising: The data acquisition module is used to acquire environmental parameters of the target sea area and foundation parameters of the target wind turbine pile foundation. The dynamic calculation module is used to calculate the hydrodynamic parameters of the target sea area based on environmental and basic parameters; The scour depth prediction module is used to calculate the ultimate equilibrium scour depth of the target wind turbine pile foundation based on hydrodynamic parameters. The model building module is used to establish a spatiotemporal evolution model that characterizes the relationship between the time scale of scour and the ultimate equilibrium scour depth, based on the law of conservation of sediment volume and the net spatial flux of sediment in the scour pit area around the target wind turbine foundation. The coefficient calibration module is used to acquire local historical scour measurement data of wind power pile foundations, perform regression fitting and calibration on the undetermined coefficients in the spatiotemporal evolution model, and obtain the calibrated spatiotemporal evolution model. The duration prediction module is used to calculate the characteristic time scale of the target wind turbine pile foundation based on the calibrated spatiotemporal evolution model and the ultimate equilibrium scour depth, and output the scour duration prediction results based on the characteristic time scale.

[0017] This invention provides a method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects. It has the following beneficial effects: 1. This invention establishes a spatiotemporal evolution model characterizing the relationship between the time scale of scour and the ultimate equilibrium scour depth by introducing the law of conservation of sediment volume and the net spatial flux of sediment in the scour pit region. Compared with traditional static prediction methods that rely solely on empirical formulas, this model derives the equation for the rate of change of scour depth by combining the theory of exponential decay, mathematically linking the time effect with the spatial evolution mechanism, effectively improving the physical rigor and computational accuracy of the prediction process for the scour history of wind turbine pile foundations.

[0018] 2. This invention utilizes historical scour measurement data of local wind turbine pile foundations to calibrate the undetermined coefficients in the spatiotemporal evolution model. By extracting measured samples under different operating conditions and uniformly converting them into dimensionless data point sets, and further combining logarithmic transformation and least squares method for linear regression, the model coefficients are solved. This model correction method based on measured data can reduce the calculation bias of purely theoretical models in complex marine environments and improve the adaptability and reliability of the prediction method in specific engineering areas.

[0019] 3. This invention can calculate the real-time scour depth based on the input time series set and compare and verify the expected final scour depth at the end of the wind farm's service life with a specific safe burial depth threshold. Since this threshold comprehensively considers the superstructure load of the target wind turbine foundation, the mechanical parameters of the surrounding soil, and the ultimate overturning stability requirements, the system can determine whether the limit is exceeded based on the actual stress state and output targeted over-limit warnings and suggested dimensions for the bottom protection structure. This provides quantitative engineering basis for structural safety assessment and protection design throughout the entire life cycle of offshore wind farms. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for predicting the scour duration of wind power pile foundations considering spatiotemporal effects according to an embodiment of the present invention; Figure 2 This is a structural block diagram of a wind power pile foundation scour duration prediction system considering spatiotemporal effects according to an embodiment of the present invention; Figure 3 This is a linear calibration fitting diagram of the spatiotemporal evolution model according to an embodiment of the present invention; Figure 4 This is a comparison chart of the scour duration prediction curves according to an embodiment of the present invention; Figure 5 This is a distribution diagram of the model prediction error in an embodiment of the present invention. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] See attached document Figure 1 This invention provides a method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects, comprising the following steps: S10, Obtain environmental parameters of the target sea area and foundation parameters of the target wind turbine pile foundation; S20, calculate the hydrodynamic parameters of the target sea area based on environmental and basic parameters; S30, calculate the ultimate equilibrium scour depth of the target wind turbine pile foundation based on hydrodynamic parameters; S40. Based on the law of conservation of sediment volume and net spatial flux of sediment in the scour pit area, a spatiotemporal evolution model of time scale and ultimate equilibrium scour depth is established. S50: Obtain historical scour measurement data to perform regression fitting and calibration of the undetermined coefficients in the spatiotemporal evolution model; S60 calculates the characteristic time scale based on the calibrated spatiotemporal evolution model and the limit equilibrium scour depth, and outputs the scour duration prediction results.

[0023] The overall workflow of this prediction method takes the basic physical quantities of wind turbine pile foundations and the sea area where they are located as inputs.

[0024] The critical depth boundary under existing water flow conditions is solved by processing S10 to S30.

[0025] In S40, this scheme mathematically correlates the spatial geometry of the scour pit with the time history of sediment transport.

[0026] A time-scale equation that takes into account both spatial scale and hydrodynamic drive is established by calculating the quantitative relationship between the rate of change of scour pit volume and the net sediment flux in the region.

[0027] After establishing the physical equations, proceed to S50.

[0028] By using measured scour data sequences, multivariate nonlinear fitting was performed to determine the sediment transport rate-related indices and dimensional consistency parameters in the spatiotemporal evolution model.

[0029] Finally, the various hydrological data were substituted into the calibrated spatiotemporal evolution model in S60.

[0030] The dimensionless timescale parameters under the target environment are obtained by solving the problem and then converted into actual characteristic time to output the time prediction data corresponding to the specified scour depth.

[0031] See attached document Figure 2 The present invention also provides a wind turbine pile foundation scour duration prediction system considering spatiotemporal effects, comprising: The data acquisition module is used to acquire environmental parameters of the target sea area and foundation parameters of the target wind turbine pile foundation.

[0032] The dynamic calculation module is used to calculate the hydrodynamic parameters of the target sea area based on environmental and basic parameters.

[0033] The scour depth prediction module is used to calculate the ultimate equilibrium scour depth of the target wind turbine foundation based on hydrodynamic parameters.

[0034] The model building module is used to establish a spatiotemporal evolution model of the time scale and the ultimate equilibrium scour depth based on the law of conservation of sediment volume and the net spatial flux of sediment in the scour pit area.

[0035] The coefficient calibration module is used to obtain historical scour measurement data to perform regression fitting and calibration of the undetermined coefficients in the spatiotemporal evolution model.

[0036] The duration prediction module is used to calculate the characteristic time scale based on the calibrated spatiotemporal evolution model and the limit equilibrium scour depth, and output the scour duration prediction results.

[0037] When the system is working, the data acquisition module transmits the collected physical data unidirectionally to the power calculation module.

[0038] The dynamic calculation module calculates dimensionless hydrological characteristic values ​​based on the physical model and transmits these characteristic values ​​to the depth prediction module and the duration prediction module, respectively.

[0039] The ultimate equilibrium scour depth output by the scour depth prediction module is fed back to the time-based prediction module as the core boundary condition.

[0040] The mathematical logic framework provided by the model building module is combined with the fitting coefficients output by the coefficient calibration module to generate specific prediction equations within the time-based prediction module.

[0041] The time-based prediction module receives the parameter variables passed from each module, performs exponential decay model calculations, and outputs a numerical sequence of scour depth that changes over time.

[0042] See attached document Figure 1 In this embodiment, the specific process of obtaining environmental parameters of the target sea area and foundation parameters of the target wind turbine pile foundation in step S10 can be decomposed into multiple data acquisition sub-steps. After the wind turbine pile foundation is installed on the seabed, it alters the local seawater flow field, causing an increase in local flow velocity and generating downward eddies. This, in turn, generates bed shear stress at the bottom, carrying away sediment and forming scour pits. To accurately predict the above-mentioned scour process, it is necessary to extract basic physical quantities involving structural features, bed soil properties, and flow field characteristics as the data basis for subsequent calculations.

[0043] S101, Obtain the structural characteristic parameters of the target wind turbine pile foundation. Specifically, this step mainly extracts the outer diameter of the water-retaining section of the target wind turbine pile foundation, and defines the above outer diameter as the pile foundation diameter. In this embodiment, the target wind turbine foundation is typically a large-diameter steel pipe monopile foundation used to support offshore wind turbine generators. The method for obtaining the structural characteristic parameters of the foundation is as follows.

[0044] S102, Obtain the basic parameters of the seabed sediment and the water physical parameters of the target sea area. In this embodiment, the basic parameters of the sediment in the environmental parameters mainly include the median particle size of the sediment. and the density ratio of silt to water The specific relationship between the density ratio of sediment and water is as follows: In the formula This represents the absolute density of the sediment particles on the seabed. This refers to the seawater density of the target sea area. The water physical parameters in the environmental parameters include the local seawater kinematic viscosity coefficient. and gravitational acceleration To obtain the median particle size and density of sediment, those skilled in the art can perform undisturbed physical sampling of surface sediments from the target seabed and conduct indoor geotechnical sieving and specific gravity tests. The median particle size of the sediment... The sieve curve of a seabed surface sample typically represents the particle size value corresponding to a cumulative weight percentage of 50%.

[0045] S103, Obtain the hydrodynamic foundation parameters of the target sea area. These parameters record the external water flow conditions that cause sediment initiation and loss at the bottom of the pile foundation, primarily including the local water depth of the target sea area. Characteristic flow velocity of water flow And wave elements. As an optional implementation, the characteristic flow velocity of the water flow. The wave parameters are calculated using the vertical average flow velocity in areas unaffected by wind turbine foundations or the bottom current velocity at a specific water depth. The main wave element includes the significant wave height. With the corresponding wave period This is used for subsequent calculations of bed shear stress under wave-flow coupling conditions. Effective wave height. With wave period Statistical characteristic values ​​or measured average values ​​within the return period of the target sea area are typically used. For obtaining water depth, current characteristic velocity, and wave elements, those skilled in the art can deploy acoustic Doppler current profilers in the target sea area to continuously observe water depth and current velocity profile data, and use wave measurement buoys to obtain wave element characteristic values.

[0046] In this embodiment, the environmental parameters and basic parameters obtained in step S10 provide fundamental data for hydrodynamic calculations. Specifically, the process of calculating the hydrodynamic parameters of the target sea area based on the environmental parameters and basic parameters in step S20 can be decomposed into multiple parameter conversion sub-steps. In this embodiment, hydrodynamic parameters are dimensionless physical quantities that reflect the flow field characteristics of the target sea area. The formation of local scour is essentially due to the shear force exerted by the water flow on the seabed sediment exceeding the sediment's own resistance to initiation; therefore, it is necessary to quantify the aforementioned dynamic input conditions.

[0047] S201, Calculate the Froude number of the target sea area based on the characteristic flow velocity, gravitational acceleration, and pile diameter. In this embodiment, the Froude number characterizes the ratio effect of the inertial force of the water flow to gravity. It should be noted that the Froude number of traditional open channel flow usually uses the local water depth as the characteristic length, while this invention addresses the local scour problem of wind turbine pile foundations. The intensity of the downward flow and horseshoe vortex in front of the pile is mainly affected by the width of the water-blocking structure; therefore, the pile diameter is used as the characteristic length. In this embodiment, the Froude number for wind turbine pile foundations... The specific calculation formula is as follows: ; In the formula, The characteristic velocity of water flow, It is the acceleration due to gravity. The diameter of the pile foundation is given.

[0048] S202, Calculate the frictional velocity of the target sea area by combining the maximum bed shear stress under wave-current coupling. In this embodiment, since the actual marine engineering environment is usually in a complex flow field where waves and currents interact, the actual drag force on the bed sediment is greater than that of pure water flow alone. Therefore, it is necessary to use the maximum bed shear stress under wave-current coupling to estimate the frictional velocity. In this embodiment, the frictional velocity... The calculation formula is: ; In the formula, This represents the maximum bed shear stress in the target sea area under wave-current coupling conditions. The density is seawater. Specifically, for the maximum bed shear stress... The derivation and calculation can be performed by those skilled in the art using wave elements and water flow characteristic velocities obtained from observations, through a nonlinear vector superposition physical model of water flow shear stress and wave shear stress.

[0049] S203, Calculate the Shields number of the target sea area based on the frictional velocity, the density ratio of sediment to water, and the median sediment particle size. In this embodiment, the Shields number, also known as the dimensionless bed shear stress, is used to characterize the relative ratio of the shear driving force of the fluid on the bed sediment particles to the effective gravity of the sediment particles, and is a conventional dimensionless parameter in sediment dynamics. In this embodiment, the Shields number... The calculation formula is as follows: ; In the formula, For frictional flow velocity, It is the acceleration due to gravity. The density ratio of sediment to water. The median particle size of the sediment.

[0050] S204, A dimensionless particle size parameter is introduced to calculate the critical Shields number for the target sea area. In this embodiment, sediment initiation is a prerequisite for scour, and the critical Shields number characterizes the critical stress state when sediment particles begin to undergo displacement. Specifically, the dimensionless particle size is calculated based on the median sediment particle size, the density ratio of sediment to water, gravitational acceleration, and the kinematic viscosity of seawater. : ; In the formula, The median particle size of the sediment is... The density ratio of sediment to water. It is the acceleration due to gravity. is the kinematic viscosity coefficient of seawater.

[0051] In this embodiment, based on dimensionless particle size Calculate the critical Shield number Critical Shields number The specific calculation formula is as follows: ; In the formula, , , as well as All of these are empirical constants derived from classical sediment motion statistics.

[0052] Shields number is calculated and the critical Shields number Then, a physical threshold comparison is performed between the two. When the condition is met... When this occurs, it indicates that the actual driving force of the water flow is greater than the resistance of the sediment, causing the sediment on the bed surface to be activated and eroded. The aforementioned formula provides a specific mathematical expression for the sediment activation criterion, using the calculated Froude number. , Shields number and the critical Shields number As an intermediate variable in the calculation, it is passed to subsequent operation steps to further quantify the limit equilibrium scour depth and predict the scour duration.

[0053] In this embodiment, the hydrodynamic parameters calculated in step S20 provide the dynamic input conditions for calculating the final shape of the scour pit. Step S30, which calculates the ultimate equilibrium scour depth of the target wind turbine foundation based on the hydrodynamic parameters, can be further divided into several sub-steps. In this embodiment, the ultimate equilibrium scour depth refers to the maximum depth reached when the seabed scour depth no longer increases with time under the action of constant water flow over a long period, representing the final spatial physical boundary of sediment loss.

[0054] S301, Establish a formula for predicting the ultimate equilibrium scour depth with the Froude number as the independent variable. In this embodiment, the local scour depth of the wind turbine pile foundation is correlated with the Froude number of the water flow. From a physical mechanism perspective, the water flow's submergence and the entrainment capacity of eddies increase with the increase of the Froude number, leading to a deeper final scour pit. To accurately predict the scour limit state of the target wind turbine pile foundation, a dimensionless exponential prediction formula is introduced for calculation. The specific calculation formula is as follows: ; In the formula, To achieve the ultimate equilibrium scour depth, The diameter of the pile foundation. The Froude number for the target sea area calculated in step S20, This is a base-10 logarithmic function. For the natural constant Exponential functions with base 0. , as well as All of these are empirical constants derived from statistical fitting of a large number of physical model experiments and field observation data.

[0055] Furthermore, the application conditions of the above formula limit the Froude number. The value of is between 0.1 and 1.1, and the Köringen-Carpenter number is also relevant. The value ranges from 0.4 to 26. In this embodiment, The number is a dimensionless parameter characterizing the wave motion. The specific calculation logic is to obtain it by multiplying the maximum horizontal track velocity of the wave bottom by the wave period and dividing by the pile diameter.

[0056] S302, Verify the physical boundary rationality of the limit equilibrium scour depth prediction formula. In this embodiment, combining the mathematical properties of the above prediction formula, when the Froude number... When the value is large, the exponential term on the right side of the formula approaches a constant, and the scouring depth will gradually approach a fixed value. The aforementioned asymptotic trend aligns with the limit equilibrium scour ratio range under the sole action of water flow given in existing studies. The results are largely consistent, proving the accuracy of the empirical formula in quantifying the final scour pattern.

[0057] S303, the absolute value of the ultimate equilibrium scour depth of the target wind turbine pile foundation is extracted through algebraic operations. In this embodiment, after obtaining the logarithmic result of the dimensionless scour depth ratio, the actual physical scale value is obtained by inverse calculation using exponential methods, combined with the already acquired pile foundation diameter. The specific conversion formula is as follows: ; In the formula, To obtain the ultimate equilibrium scour depth, the unit is the same as the input pile diameter. The units are kept consistent. In this embodiment, the calculated ultimate equilibrium scour depth is... This will be used as the spatial asymptotic boundary condition for constructing the time evolution equation and passed to the next computational step.

[0058] In this embodiment, based on the aforementioned steps to obtain the ultimate equilibrium scour depth, step S40 establishes a spatiotemporal evolution model of the time scale and the ultimate equilibrium scour depth according to the law of conservation of sediment volume and the net spatial flux of sediment in the scour pit area. In this embodiment, the spatiotemporal evolution model provides a theoretical basis for predicting the dynamic development process of scour depth, and the specific calculation process includes the following sub-steps.

[0059] S401, Establish the correlation equation between the net sediment flux and the volume change rate of the scour pit. In this embodiment, it is assumed that the development process of the scour pit around the wind turbine foundation follows the law of morphological similarity, that is, the overall geometric outline of the scour pit maintains a fixed proportion as it expands downward. Specifically, a standard scour pit radius is defined. Surface area of ​​scour pit Based on this, the volume of the scour pit was determined. By performing the area integral calculation, we can obtain: ; In the formula, For scouring depth, For scouring the pit area, , and All are shape coefficients characterizing the geometric features of the scour pit. In this embodiment, from a physical process analysis, the reason why the scour pit continuously deepens is essentially because the bottom water flow carries away the sediment in the area. Regarding the aforementioned scour pit volume... Regarding time Taking the derivative, the rate of change of sediment volume in the scour pit can be expressed as: ; At the same time, according to the law of conservation of sediment volume, the net flux of sediment outward from the scour pit area... The specific expression is: ; In the formula, This represents the sediment transport rate vector per unit width. For the boundary normal vector, For sediment transport rate The divergence is used to characterize the rate of sediment loss per unit area of ​​seabed. Based on the physical relationship that the rate of volume change equals the net sediment flux (i.e.,...),... The derivation yields: ; In the formula, This represents the average sediment dispersion within the scour pit area. In this embodiment, due to the area... and By absorbing and simplifying the constant terms on both sides of the equation, we can deduce that the rate of change of scour depth and sediment dispersion are numerically proportional and equivalent. This equivalent relationship can be expressed as: ; S402, Derivation of the characteristic time scale using an exponential decay model of scour depth. In this embodiment, an exponential decay model is introduced to describe the development law of scour depth over time: ; Real-time scouring depth This refers to the scouring duration experienced by the wind turbine foundation in the target sea area. For the natural constant An exponential function with base 0. For the aforementioned scour duration curve formula with respect to any time... Differentiate to obtain the equation for the rate of change of scour depth: ; Substituting the above derivative result into the correlation equation obtained in step S401, we can equivalently transform it to obtain: ; In this embodiment, at the very beginning of the scouring process, no pits or depressions form on the seabed surface to obstruct the flow, resulting in a more concentrated water flow and the scouring rate reaching its maximum in the initial stage. At any given time... When the exponent term equals 1, the characteristic time scale is obtained. The specific expression: ; S403, introduce the bedload transport rate under flat-bed conditions for dynamic replacement. In this embodiment, at any time... At that time, the seabed was in a flat state, and the initial sediment spread at the aforementioned moment was directly proportional to the ratio of the initial sediment transport rate per unit width to the pile diameter: ; In the formula, The diameter of the pile foundation. Let be the sediment transport rate under flat bed conditions. The sediment transport rate under flat bed conditions is expressed using a bed transport kinetics formula: ; In the formula, For Shields number, The critical Shields number, For the empirical index of sediment transport rate to be calibrated, The density ratio of sediment to water. It is the acceleration due to gravity. The median particle size of the sediment is given. It should be noted that, considering the strong subsurface currents and horseshoe-shaped vortices generated by the water obstruction of the wind turbine pile foundation, which have a strong entrainment effect on the bottom sediment, the starting resistance of the surface sediment to displacement is weakened. Therefore, the following method is adopted. This is used to replace the conventional critical start threshold in order to more accurately quantify the power drive.

[0060] S404, Construct a dimensionless timescale theoretical model incorporating spatial scale and dynamic driving forces. In this embodiment, the initial sediment divergence ratio obtained in step S403 and the sediment transport rate formula are substituted into the characteristic timescale obtained in step S402. From the equation, we can obtain: ; To standardize the characteristic time scale, a dimensionless time scale calculation formula is introduced. , which is a dimensionless time scale.

[0061] ; By combining the various proportional coefficients from the aforementioned derivation process, a theoretical model for the time-scale development of scour is established: ; In the formula, For a dimensionless time scale, This is a comprehensive coefficient. In this embodiment, the comprehensive coefficient... The shape factor introduced in the aforementioned derivation steps was incorporated. , , All constant proportional terms generated during the area and divergence conversion process are set as a unified parameter to be calibrated. The aforementioned theoretical model uses a dimensionless timescale. Spatial scale characteristics and power drive items A connection was established, the aforementioned coefficients and These parameters are passed on as undetermined constants to subsequent model parameter calibration steps.

[0062] In this embodiment, after constructing the spatiotemporal evolution model framework that includes spatial scale and dynamic driving force, step S50 acquires historical scour measurement data to perform regression fitting and calibration on the undetermined coefficients in the spatiotemporal evolution model. In this embodiment, the undetermined coefficients in the theoretical model comprehensively include complex physical processes such as sediment transport laws and the evolution of scour pit geometry, and cannot be directly derived accurately through pure theoretical derivation. Therefore, statistical calibration is required through physical experiments or field observation data to ensure the accuracy of the model's calculated output. The aforementioned calibration process specifically includes the following sub-steps.

[0063] S501, acquire historical measured data of local scour of wind turbine pile foundations. In this embodiment, historical scour data samples under different hydrodynamic and geological conditions are collected as the data basis for regression fitting. The aforementioned historical measured data samples include measured values ​​of characteristic time scales, measured values ​​of limit equilibrium scour depths, characteristic flow velocities, pile diameters, and median sediment particle sizes under the corresponding operating conditions. For the extraction of measured values ​​of characteristic time scales, those skilled in the art can collect long-sequence historical scour depth observation sequences and use a standard exponential decay model for inverse fitting. The relevant characteristic time scale extraction and processing is a well-known technique in the field and will not be described in detail here.

[0064] S502, Calculate the dimensionless intermediate parameters corresponding to the theoretical model based on historical measured data. In this embodiment, each collected historical measured data sample is substituted into the calculation formula of the previous step. Specifically, the dimensionless time scale of the corresponding sample is calculated by combining the measured values ​​of pile diameter, median sediment particle size, and characteristic time scale; the Shields number of the corresponding sample is calculated by combining the characteristic flow velocity of the water flow; and the dimensionless scour spatial scale of the corresponding sample is calculated by combining the measured values ​​of pile diameter and ultimate equilibrium scour depth. Through the above calculations, a standard dimensionless data point set for parameter fitting is extracted.

[0065] S503, Logarithmic linearization transformation is performed on the spatiotemporal evolution model framework. In this embodiment, the previously derived spatiotemporal evolution model is in power function form, and direct nonlinear fitting can easily produce large calculation errors. To improve the stability of parameter calibration, a logarithmic transformation is performed on both sides of the model equation to achieve linearization. For the theoretical model... Taking the natural logarithm of both sides of the equation, we can derive: ; In the formula, The function is the natural logarithm operation. For a dimensionless time scale, To achieve the ultimate equilibrium scour depth, The diameter of the pile foundation. For Shields number, The critical Shields number, The empirical index for sediment transport rate to be calibrated. The comprehensive coefficients are to be calibrated. In this embodiment, the dependent variable is defined to construct the standard linear regression equation. and independent variable : ; ; By substituting variables, the original theoretical model is transformed into a standard linear function equation: ; S504, the least squares method is used to perform regression fitting on the linearized equation, and the constant values ​​of the undetermined coefficients are extracted. In this embodiment, all the obtained dimensionless data points are substituted into the dependent variable. With independent variable The calculation formula yields a series of two-dimensional scattered point coordinates. A linear regression is then performed on these coordinates using the least squares method to calculate the optimal line equation that minimizes the sum of squared residuals from all data points to the regression line. The slope of the optimal line equation is then extracted. With intercept Solve for the undetermined coefficients in the original model based on mathematical correspondences: ; ; In the formula, This is an empirical index for sediment transport rate. This is a comprehensive coefficient. For the natural constant The exponential function with base 0. In this embodiment, the calculated constant value will be... and Substituting back into the original theoretical model framework, the parameters of the spatiotemporal evolution model were calibrated. The calibrated spatiotemporal evolution model established a clear mathematical relationship between the time scale and the dynamic conditions, and passed this relationship to the scour duration prediction step.

[0066] In this embodiment, after the parameters of the spatiotemporal evolution model are calibrated in the aforementioned steps, step S60 calculates the characteristic time scale based on the calibrated spatiotemporal evolution model and the limit equilibrium scour depth, and outputs the scour duration prediction result. In this embodiment, the aforementioned steps obtain the basic parameters required for prediction, providing direct data support for the scour protection design of offshore wind turbine foundations. The specific calculation and output process includes the following sub-steps.

[0067] S601, Based on the hydrodynamic parameters and ultimate equilibrium scour depth of the target sea area, calculate the dimensionless time scale of the target wind turbine foundation. In this embodiment, the Shield number and critical Shield number of the target sea area obtained in step S20, and the ultimate equilibrium scour depth obtained in step S30, are substituted into the spatiotemporal evolution model calibrated in step S50. The specific calculation formula is as follows: ; In the formula, For the dimensionless timescale obtained from the prediction, The ultimate equilibrium scour depth of the target wind turbine foundation. The diameter of the pile foundation. The Shields number for the target sea area. The critical Shields number, To calibrate the obtained empirical index of sediment transport rate, The comprehensive coefficients are obtained for calibration. In this embodiment, the time scale values ​​under specific dynamic conditions are calculated using the aforementioned formula. S602, the dimensionless time scale is restored to its original dimension to extract characteristic time scales with real physical meaning. In this embodiment, the dimensionless time scale is an intermediate parameter constructed to facilitate model building and parameter fitting. For actual engineering prediction, it is necessary to restore the dimensionless time scale to an absolute value in time units. The relationship of the dimensionless time scale constructed in the previous step is used for reverse calculation: ; In the formula, The timescale reflects real physical characteristics, and the units are consistent with conventional time units. The dimensionless timescale obtained from the aforementioned steps, The diameter of the pile foundation. The density ratio of sediment to water. It is the acceleration due to gravity. The median grain size of sediment in the target sea area. In this embodiment, the characteristic time scale is... Physically, it represents the time elapsed until the scour depth reaches approximately 63.2% of the ultimate equilibrium scour depth, reflecting the rate of scour pit development. From an engineering protection principle perspective, understanding the development process of scour pits over time helps assess the structural safety status of wind turbine foundations at different service stages, avoiding overly conservative or insufficient scour protection designs.

[0068] S603, Construct a dynamic prediction model for the scour history of the target wind turbine foundation. In this embodiment, after obtaining the characteristic time scale and the ultimate equilibrium scour depth, the calculated parameters are substituted into the exponential decay model in step S402 to calculate the scour history at any given time. Real-time scouring depth .

[0069] S604, Based on the dynamic prediction model of scour duration, the system outputs the prediction results and applies them to engineering evaluation. In this embodiment, a preset time series set is input, and the corresponding real-time scour depth set is calculated using the aforementioned duration prediction model. The aforementioned time series set is used as the horizontal axis, and the corresponding real-time scour depth set is used as the vertical axis to generate a duration prediction chart of scour depth changing over time. Engineering designers can extract the end-of-service time corresponding to the design service life of the wind farm from the aforementioned preset time series set, and calculate the corresponding expected final scour depth using the dynamic prediction model of scour duration. Subsequently, a preset safe burial depth threshold for wind turbine pile foundations is obtained. The aforementioned safe burial depth threshold is pre-calculated and determined based on the upper combined load of the target wind turbine pile foundation, the mechanical parameters of the soil around the pile, and the ultimate overturning stability requirements. The expected final scour depth is compared and verified with the safe burial depth threshold. If it is determined that the expected final scour depth is greater than the safe burial depth threshold, the system generates an over-limit warning signal and outputs the suggested protection dimensions of the anti-scour bottom protection structure, providing a direct basis for guiding the design of the dimensions and thickness of anti-scour protection measures such as riprap and sandbags in engineering. If the system determines that the expected final scour depth is less than or equal to the safe burial depth threshold, it will generate a safety assessment pass signal, indicating that the current design of the target wind turbine foundation meets the scour prevention safety requirements.

[0070] Specific application examples: To further illustrate the scientific validity and effectiveness of the wind turbine pile foundation scour duration prediction method considering spatiotemporal effects of the present invention, the following detailed calculation process and verification results of the present invention are presented in conjunction with a specific case study of a nearshore wind farm monopile foundation project.

[0071] Basic Data Acquisition: In this embodiment, a large-diameter monopile foundation of a near-shore wind farm is selected as the target wind turbine foundation. The following foundation parameters were obtained through on-site survey: Pile foundation outer diameter: .

[0072] Environmental and sediment parameters: median sediment particle size (i.e., 0.0003m), the density ratio of sediment to water Gravitational acceleration Seawater kinematic viscosity coefficient .

[0073] Hydrodynamic parameters: characteristic current velocity in the target sea area Frictional velocity calculated by wave-current coupling .

[0074] Hydrodynamic parameter quantification involves substituting the above parameters into the hydrodynamic calculation module: Froude number calculation .

[0075] Dimensionless particle size calculation: .

[0076] according to Calculate the critical Shield number .

[0077] Actual Shields number of the target sea area .because If the conditions for sediment initiation are met, the system determines that significant scouring will occur.

[0078] Solving the limit equilibrium scour depth using Froude numbers Calculate the ultimate equilibrium scour depth of the target pile foundation : Substitute into the formula The ultimate equilibrium scour depth under the target working condition can be calculated. m.

[0079] The parameter calibration and solution system calls upon historical measured scour data from the surrounding sea area. The dependent variable is extracted by taking the natural logarithm of both sides of the theoretical model equation. and independent variable A two-dimensional scattered set of points.

[0080] From this, the undetermined coefficient, the empirical index of sediment transport rate, can be calculated. Comprehensive coefficient .

[0081] Feature time calculation and early warning assessment: Substitute the target operating condition data into the calibrated model: Calculating dimensionless time scales

[0082] Dimensional reduction to obtain feature time scale: Hours. The system outputs the real-time scour depth analytical equation: .

[0083] Inputting the end date of the wind farm's 25-year service life, the system calculates that the final scour depth is expected to approach 8.25m. At this point, the system extracts the preset safe burial depth threshold for wind turbine pile foundations (set to 10.0m). Since 8.25m ≤ 10.0m, the system generates a safety assessment pass signal, determining that the current structure meets the scour prevention safety requirements.

[0084] Experimental verification and effect comparison: To verify the accuracy of the dynamic prediction model for scour duration constructed in this invention, a long-sequence verification experiment lasting 500 hours was conducted in this embodiment, and the model was compared and evaluated with the traditional empirical prediction model with fixed parameters in the prior art.

[0085] See attached documentFigure 3 This embodiment shows the linear calibration fitting plot of the spatiotemporal evolution model. (See attached image.) Figure 3 Hollow circles represent the scatter points of historical measured data after dimensionless processing, and solid lines represent the optimal regression line extracted using the least squares method. The distribution pattern shows that the scatter points of the measured data converge highly to the straight line. The two sides. The coefficient of determination obtained by the system solution ( The coefficient reached 0.91, proving that the comprehensive coefficient extracted in this invention is accurate. With experience index It can highly reproduce the complex spatiotemporal evolution laws in actual engineering, and the parameter calibration results have high physical reliability.

[0086] See attached document Figure 4 This embodiment shows a comparison of predicted scour duration curves over a period of 500 hours. (Attached) Figure 4 The horizontal axis represents scour time, and the vertical axis represents real-time scour depth. Hollow circles in the figure represent field-measured data, smooth solid lines represent the prediction curves of the model in this invention, and dashed lines represent the prediction curves of traditional empirical models. The comparison reveals that in the initial development stage of scour initiation (0 to 100 hours), the solid line almost perfectly matches the hollow circle, accurately capturing the rapid scour phenomenon caused by strong submerged eddies; while the traditional empirical model represented by the dashed line exhibits significant response lag. In the stage of gradual and near-limit scour (100 to 500 hours), the solid line steadily approaches the limit depth of 8.25m; while the dashed line fails to accurately quantify boundary resistance, ultimately resulting in an overestimation prediction of over 1.2m.

[0087] See attached document Figure 5 This embodiment illustrates the distribution of model prediction errors at different time points. (See attached image.) Figure 5 The absolute residuals between predicted and measured values ​​were statistically analyzed using a double bar chart. In the chart, solid-filled bars represent the absolute error of the model of this invention, while hollow-framed bars with blank interiors represent the absolute error of the traditional empirical model. A direct comparison shows that the height of the solid bars remains relatively low throughout the 500-hour time axis and does not exhibit any divergence or amplification over time, while the error of the hollow bars increases sharply in the later stages of service.

Claims

1. A method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects, characterized in that, Includes the following steps: Obtain environmental parameters of the target sea area and foundation parameters of the target wind turbine pile foundation; Calculate the hydrodynamic parameters of the target sea area based on the environmental parameters and the basic parameters; Based on the hydrodynamic parameters, the ultimate equilibrium scour depth of the target wind turbine pile foundation is calculated; Based on the law of conservation of sediment volume and net spatial flux of sediment in the scour pit area around the target wind turbine pile foundation, a spatiotemporal evolution model is established to characterize the relationship between the scour time scale and the ultimate equilibrium scour depth. Historical scour measurement data of local wind power pile foundation is obtained, and regression fitting and calibration are performed on the undetermined coefficients in the spatiotemporal evolution model to obtain the calibrated spatiotemporal evolution model. Based on the calibrated spatiotemporal evolution model and the ultimate equilibrium scour depth, the characteristic time scale of the target wind turbine pile foundation is calculated, and the scour duration prediction result is output based on the characteristic time scale.

2. The method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 1, characterized in that, The basic parameters include the pile diameter; the environmental parameters include the median particle size of sediment, the density ratio of sediment to water, the characteristic flow velocity of water, the kinematic viscosity coefficient of seawater, and the gravitational acceleration. The step of calculating the hydrodynamic parameters of the target sea area based on the environmental parameters and the basic parameters includes: The Froude number, which characterizes the effect of inertial force of the water flow, is calculated based on the characteristic flow velocity, the gravitational acceleration, and the pile diameter. The maximum bed shear stress under wave-current coupling state is calculated based on the environmental parameters, and the frictional velocity of the target sea area is obtained by combining the seawater density. The calculated frictional velocity is combined with the density ratio of sediment to water and the median particle size of the sediment to calculate the Shield number, which characterizes the shear driving force of the water flow on the sediment. The dimensionless particle size is calculated based on the median particle size of the sediment, the density ratio of the sediment to water, the gravitational acceleration, and the seawater kinematic viscosity coefficient. The critical Shield number, which characterizes the critical resistance to sediment initiation, is then calculated based on the dimensionless particle size. The calculated Froude number, Shields number, and critical Shields number are combined to form the hydrodynamic parameter.

3. The method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 2, characterized in that, The calculation of the ultimate equilibrium scour depth of the target wind turbine pile foundation based on the hydrodynamic parameters includes: Extract the Froude number from the hydrodynamic parameters and establish an exponential prediction formula with the Froude number as the independent variable; Substitute the Froude number into the exponential prediction formula to calculate the dimensionless scour depth ratio. The ultimate equilibrium scour depth of the target wind turbine pile foundation is calculated by multiplying the dimensionless scour depth ratio by the pile diameter.

4. The method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 3, characterized in that, The spatiotemporal evolution model, which characterizes the relationship between the scour timescale and the ultimate equilibrium scour depth, is established based on the law of conservation of sediment volume and the net spatial flux of sediment in the scour pit area surrounding the target wind turbine foundation. This includes: Define the rate of change of the volume of the scour pit with respect to time, and calculate the net flux of sediment outward from the scour pit area according to the law of conservation of sediment volume. By establishing an equal relationship between the volume change rate and the net sediment flux, a correlation equation is derived in which the change rate of scour depth is proportional to the average sediment dispersion within the scour pit area. An exponential decay model incorporating a characteristic time scale and the ultimate equilibrium scour depth is introduced. The derivative of the exponential decay model with respect to time is used to obtain the equation for the rate of change of the scour depth. Substituting the rate of change equation of the scour depth obtained by differentiation into the correlation equation, an algebraic expression for the characteristic time scale containing the average sediment dispersion at the initial moment is derived. The average sediment dispersion at the initial moment under the flat bed condition is equivalently replaced by the ratio of the initial unit width sediment transport rate to the diameter of the pile foundation. A bedload kinetics formula containing an empirical index of the sediment transport rate to be calibrated is introduced to represent the initial unit width sediment transport rate. The initial unit width sediment transport rate is then substituted into the characteristic time scale expression for variable substitution. A dimensionless time scale is introduced to standardize the characteristic time scale expression after variable substitution. The proportional constants generated during the conversion process are combined into a comprehensive coefficient to be calibrated. Finally, a spatiotemporal evolution model is established that includes the dimensionless time scale, the limit equilibrium scour depth, the empirical index of sediment transport rate, and the comprehensive coefficient.

5. The method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 4, characterized in that, The process of acquiring historical scour measurement data of local wind turbine pile foundations, performing regression fitting and calibration on the undetermined coefficients in the spatiotemporal evolution model, and obtaining the calibrated spatiotemporal evolution model includes: Acquire historical scour measurement data samples under different water flow conditions, and extract the characteristic time scale measurement values, limit equilibrium scour depth measurement values, water flow characteristic velocity, sample pile diameter, and sample sediment median particle size corresponding to the historical scour measurement data samples. The dimensionless time scale of the corresponding sample is calculated based on the sample pile diameter, the median particle size of the sample sediment, and the measured value of the characteristic time scale. The Shield number of the corresponding sample is calculated in combination with the characteristic flow velocity of the water flow. The dimensionless scour spatial scale of the corresponding sample is calculated based on the sample pile diameter and the measured value of the ultimate equilibrium scour depth. The dimensionless time scale, the Shields number, and the dimensionless scour spatial scale corresponding to the same data sample are mapped and combined to generate a standard dimensionless data point set for fitting the parameters of the spatiotemporal evolution model.

6. The method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 5, characterized in that, After generating the standard dimensionless data point set for fitting the parameters of the spatiotemporal evolution model, the method further includes: By taking the natural logarithm of both sides of the equation of the spatiotemporal evolution model, a logarithmic transformation is performed to obtain the logarithmically transformed spatiotemporal evolution model. Based on the spatiotemporal evolution model after the logarithmic transformation, the dependent and independent variables are defined, and the spatiotemporal evolution model is converted into a standard linear function equation composed of the dependent and independent variables. Substitute the standard dimensionless data point set into the definitional relationship between the dependent variable and the independent variable contained in the standard linear function equation to calculate and generate the corresponding two-dimensional scattered point coordinate set; The least squares method is used to perform linear regression on the two-dimensional scattered coordinate set to obtain the slope and intercept of the optimal regression line; The specific constant values ​​of the undetermined coefficients in the spatiotemporal evolution model are calculated using the slope and intercept, and then the specific constant values ​​are substituted back into the spatiotemporal evolution model to complete the model calibration.

7. A method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 6, characterized in that, The step of calculating the characteristic time scale of the target wind turbine foundation based on the calibrated spatiotemporal evolution model and the ultimate equilibrium scour depth includes: Substitute the Shields number and the critical Shields number from the hydrodynamic parameters, along with the ultimate equilibrium scour depth, into the calibrated spatiotemporal evolution model to calculate the dimensionless timescale prediction value under the target dynamic conditions. By using the conversion formula of the dimensionless time scale, the predicted value of the dimensionless time scale is restored to a characteristic time scale with an absolute time unit through reverse calculation.

8. The method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 7, characterized in that, The output of the scour duration prediction result based on the characteristic time scale includes: The characteristic time scale and the ultimate equilibrium scour depth are substituted into the exponential decay model as boundary control parameters of time and space to construct a dynamic prediction model of scour history specific to the target wind power pile foundation. A preset time series set is input into the dynamic prediction model of scour duration, and the real-time scour depth set corresponding to each time node in the time series set is calculated through model decay calculation. Using the preset time series set as the horizontal axis and the corresponding real-time scour depth set as the vertical axis, a scour depth prediction chart that continuously changes over time is generated and output as the scour duration prediction result.

9. A method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects according to claim 8, characterized in that, After generating and outputting the historical prediction chart of scour depth changing continuously over time, the method further includes: Extract the end-of-service time corresponding to the design service life of the wind farm from the preset time series set; The predicted final scour depth corresponding to the end of service is calculated using the aforementioned scour duration dynamic prediction model. Obtain a preset safe burial depth threshold for wind turbine pile foundations. The safe burial depth threshold is pre-calculated and determined based on the upper combined load of the target wind turbine pile foundation, the mechanical parameters of the soil around the pile, and the ultimate overturning stability requirements. The predicted final scour depth is compared and verified with the safe burial depth threshold. If it is determined that the expected final scour depth is greater than the safe burial depth threshold, an over-limit warning signal is generated and the recommended protection dimensions of the anti-scour bottom protection structure are output. If the estimated final scour depth is determined to be less than or equal to the safe burial depth threshold, a safety assessment pass signal is generated, indicating that the current design of the target wind turbine foundation meets the scour prevention safety requirements.

10. A wind turbine pile foundation scour duration prediction system considering spatiotemporal effects, characterized in that, A method for predicting the scour duration of wind turbine pile foundations considering spatiotemporal effects as described in any one of claims 1-9, comprising: The data acquisition module is used to acquire environmental parameters of the target sea area and foundation parameters of the target wind turbine pile foundation. A dynamic calculation module is used to calculate the hydrodynamic parameters of the target sea area based on the environmental parameters and the basic parameters; The scour depth prediction module is used to calculate the ultimate equilibrium scour depth of the target wind turbine pile foundation based on the hydrodynamic parameters. The model building module is used to establish a spatiotemporal evolution model that characterizes the relationship between the scour time scale and the ultimate equilibrium scour depth, based on the law of conservation of sediment volume and the net spatial flux of sediment in the scour pit area around the target wind turbine pile foundation. The coefficient calibration module is used to acquire local historical scour measurement data of wind power pile foundation, perform regression fitting and calibration on the undetermined coefficients in the spatiotemporal evolution model, and obtain the calibrated spatiotemporal evolution model. The duration prediction module is used to calculate the characteristic time scale of the target wind turbine pile foundation based on the calibrated spatiotemporal evolution model and the ultimate equilibrium scour depth, and output the scour duration prediction result based on the characteristic time scale.

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