Method and system for scour protection of offshore wind foundation

Abstract

The present application relates to a kind of offshore wind power foundation scour protection method and system, belong to offshore wind power protection technical field.It includes the following steps: by multibeam bathymetric sonar array and vibration sensor array, real-time acquisition offshore wind power single pile foundation surrounding seabed elevation field and pile vibration response frequency;Based on seabed elevation field, calculate scour depth, scour expansion rate, combined with the change of pile vibration response frequency, obtain the residual bearing capacity of pile foundation by structural dynamic inversion model;Then according to the scour depth and residual bearing capacity, construct double-parameter risk judgment criterion, divide stable state, development state, dangerous state three grades of scour risk level;Then according to the risk level, execute adaptive protection strategy, stable state maintains routine monitoring, development state puts flexible spoiler unit, dangerous state implements targeted grouting;Finally, verify the protection effect, upgrade protection level if invalid, effective then continue to monitor circulation.The present application can improve the accuracy and efficiency of scour protection.

Description

Technical Field

[0001] This invention belongs to the field of offshore wind power protection technology, specifically relating to a method and system for protecting offshore wind power foundations from scour. Background Technology

[0002] Offshore wind turbine foundations operate in a complex marine dynamic environment. Under the combined influence of waves and currents, seabed sediment is easily transported, leading to large localized scour pits around the piles. Existing scour protection technologies suffer from the following drawbacks: "Passive" protection, lacking timeliness: Traditional rockfill protection is typically completed all at once during the initial construction phase of the wind farm, or only after severe scour is discovered. This approach is not only costly but also unable to address new risks arising from subsequent seabed evolution; "One-size-fits-all" operation, lacking specificity: Regardless of the size or depth of the scour pit, traditional methods often employ full-coverage rockfill or soil stabilization. This not only wastes materials in the early stages of scour but can also induce secondary scour by altering the local topography; Lack of closed-loop feedback: After the implementation of existing protection measures, few systems can assess the effectiveness of the protection in real time and automatically adjust the strategy.

[0003] Therefore, there is an urgent need for an adaptive graded protection method that can intelligently select different means such as "turbulence suppression" or "grouting repair" according to different stages of scour development. Summary of the Invention

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] This invention provides a method for protecting offshore wind turbine foundations from scour, comprising the following steps:

[0006] S1. Real-time acquisition of the seabed elevation field and pile vibration response frequency around the offshore wind turbine monopile foundation;

[0007] S2. Calculate the scour depth based on the seabed elevation field. and scour expansion rate By combining the changes in the vibration response frequency of the pile, the remaining bearing capacity is obtained through a structural dynamic inversion model. ;

[0008] S3, based on scouring depth and remaining bearing capacity A two-parameter risk assessment criterion is established to determine the current scour risk level; by incorporating the remaining bearing capacity index into scour protection decisions, the risk of misjudgment caused by relying solely on scour depth assessment can be avoided.

[0009] S4. Execute adaptive protection strategies based on the current scouring risk level;

[0010] S5. After implementing the protection strategy, determine whether the protection is effective; if ineffective, automatically upgrade the flushing level and implement the corresponding level of protection strategy; if effective, perform continuous monitoring.

[0011] Further, S1 specifically includes: deploying a multibeam echo sounder array and a vibration sensor array around the offshore wind turbine monopile foundation; transmitting a fan-shaped sound beam to the seabed using the multibeam echo sounder and receiving the echo signal; calculating the depth value of each measuring point based on the sound wave propagation time to obtain a discrete depth measuring point set; constructing a continuous seabed elevation function from the discrete depth measuring point set through spatial interpolation to obtain the seabed elevation field; the real-time seabed elevation function is denoted as... Compared to traditional single-point sounding, it can achieve full-area, dynamic monitoring of the seabed topography around the pile, and the calculation of scour depth and scour pit range is more accurate;

[0012] By collecting the vibration response frequency of the pile body through vibration sensors, real-time structural dynamic data is provided for the subsequent inversion of the remaining bearing capacity of the pile foundation, realizing dual-dimensional monitoring of seabed topography and pile foundation structure.

[0013] Furthermore, in S2, the scour depth is obtained by calculating the difference between the initial unscourized reference seabed elevation and the currently measured lowest point seabed elevation, as expressed by the following formula:

[0014] ,

[0015] in, Indicates the depth of scouring; This indicates the initial, un-scoured baseline seabed elevation; Indicates the current time The seabed elevation at the lowest point was measured.

[0016] Furthermore, the scouring expansion rate mentioned in S2 is determined based on the rate of change of scouring volume over time, as expressed by the following formula:

[0017] ,

[0018] in, Indicates the scouring and spreading rate; Indicates the area of ​​the scour pit; Represents the seabed elevation field; This represents a small area element.

[0019] Furthermore, the inversion calculation of residual bearing capacity described in S2 introduces a soil weakening coefficient, which correlates the scour propagation rate with soil strength deterioration. This better reflects the actual engineering characteristics of soil-pile interaction in offshore wind power foundations, making the inversion results of residual bearing capacity more accurate. The formula is expressed as follows:

[0020] ,

[0021] in, Indicates the design load-bearing capacity; Indicates the depth of the pile foundation into the soil; This indicates the nonlinearity of pile-soil interaction; The soil weakening coefficient is expressed by the formula: , where k represents the soil disturbance sensitivity coefficient.

[0022] Furthermore, the two-parameter risk assessment criterion described in S3 is as follows:

[0023] Level 1: and It is a stable state;

[0024] Level 2: or , is the suppressed state;

[0025] Level 3: or It is in a repaired state;

[0026] Among them, Level 3 is the highest risk level, and Level 1 is the lowest risk level; Indicates the safety threshold. D is the pile diameter; Indicates the warning threshold. .

[0027] Furthermore, S4's adaptive protection strategy is as follows:

[0028] Steady state: Maintain regular monitoring frequency, collect data, and determine the risk level of erosion.

[0029] Suppression state: Deploy flexible flow disturbance units; the deployment coordinates of the flexible flow disturbance units are determined by the lower flow field optimization algorithm;

[0030] Repair state: Targeted grouting is performed; the formula for calculating the grouting volume is:

[0031] ,

[0032] in, Indicates the grouting volume; Indicates the fill factor; This represents the projected area of ​​the scour pit. Indicates the maximum permissible scouring depth; This indicates the seabed elevation at the moment of restoration determination.

[0033] Furthermore, the conditions for determining the effectiveness of protection in S5 are as follows: ,in, This represents the threshold for the scour stability criterion, which is the upper limit of the allowable rate of change of scour depth.

[0034] This invention also provides an offshore wind turbine foundation scour protection system, which implements the above-described offshore wind turbine foundation scour protection method, including:

[0035] Data acquisition module: used to acquire the seabed elevation field and pile vibration response frequency around the offshore wind turbine monopile foundation in real time;

[0036] Calculation module: used to calculate the scour depth and scour propagation rate based on the seabed elevation field, and obtain the remaining bearing capacity through the structural dynamic inversion model by combining the changes in the vibration response frequency of the pile.

[0037] Risk level assessment module: used to formulate a two-parameter risk assessment criterion based on scour depth and remaining bearing capacity, and determine the current scour risk level;

[0038] Adaptive protection module: Used to execute adaptive protection strategies based on the current scour risk level;

[0039] Protection judgment module: used to determine whether the protection is effective; if ineffective, it automatically upgrades the flushing level and executes the corresponding level of protection strategy; if effective, it performs continuous monitoring.

[0040] The advantages of this invention are:

[0041] This invention employs an integrated deployment of a multibeam echo sounder array and a vibration sensor array to achieve real-time, dynamic, dual-dimensional monitoring of the seabed elevation field and pile vibration response frequency across the entire domain. This allows for more accurate calculations of scour depth and scour pit extent, and provides reliable real-time structural dynamic data for the inversion of the pile foundation's residual bearing capacity. By introducing a soil weakening coefficient related to the scour propagation rate into the residual bearing capacity inversion calculation, and combining it with the nonlinear index of pile-soil interaction, the invention comprehensively considers the influence of multiple factors on the pile foundation's bearing capacity, making the residual bearing capacity inversion results more consistent with the actual engineering characteristics of pile-soil interaction in offshore wind power foundations and the actual working conditions under marine dynamic environments. By constructing a quantitative risk assessment criterion based on two parameters—scour depth and remaining bearing capacity—and incorporating the remaining bearing capacity index into scour protection decisions, precise scour risk level classification can be achieved. An innovative, differentiated, adaptive, and graded protection strategy is employed, matching stable, suppressed, and repair states. This approach abandons the traditional "full coverage" one-size-fits-all approach. In the stable state, only routine monitoring is maintained to avoid ineffective operations. In the suppressed state, flexible flow-disrupting units are deployed at precisely calculated locations to suppress scour development at its source. In the repair state, targeted grouting is implemented through formula-quantified calculation of grouting volume to achieve precise repair of scour pits. This approach reduces material waste, avoids the risk of secondary scour, and enhances the targeted nature of protection. Attached Figure Description

[0042] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0043] Figure 1 This is a flowchart of the steps of the method of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] In this embodiment, as Figure 1 As shown, this invention provides a method for protecting offshore wind turbine foundations from scour, the specific steps of which include:

[0047] S1. Real-time acquisition of the seabed elevation field and pile vibration response frequency around the offshore wind turbine monopile foundation;

[0048] Specifically, a ring-shaped scanning multibeam echo sounder array and a distributed vibration sensor array for the pile are deployed around the monopile foundation of an offshore wind turbine. The multibeam echo sounder emits a fan-shaped sound beam towards the seabed and receives the echo signal. The depth value of each measuring point is calculated based on the sound wave propagation time, resulting in a discrete set of measuring points. A continuous seabed elevation function is constructed from the discrete depth measuring point set through spatial interpolation, yielding the seabed elevation field. The real-time seabed elevation function is denoted as... The vibration response frequency of the pile is collected by a vibration sensor.

[0049] S2. Calculate the scour depth based on the seabed elevation field. and scour expansion rate By combining the changes in the vibration response frequency of the pile, the remaining bearing capacity is obtained through a structural dynamic inversion model. ;

[0050] This invention, through quantitative calculation of scour depth and propagation rate, can achieve a quantitative description of the scour development state and accurately reflect the development trend of scour.

[0051] Specifically, the scour depth is obtained by calculating the difference between the initial unscourized reference seabed elevation and the currently measured lowest point seabed elevation, as expressed by the following formula:

[0052] ,

[0053] in, Indicates the depth of scouring; This indicates the initial, un-scoured baseline seabed elevation; Indicates the current time The seabed elevation at the lowest point was measured.

[0054] The scour propagation rate is determined based on the rate of change of scour volume over time, expressed by the following formula:

[0055] ,

[0056] in, Indicates the scouring and spreading rate; Indicates the area of ​​the scour pit; Represents the seabed elevation field; This represents a small area element.

[0057] The inversion calculation of residual bearing capacity incorporates a soil weakening coefficient and correlates it with the scour propagation rate. It also combines this with the nonlinear index of pile-soil interaction, comprehensively considering the influence of various factors such as scour depth, scour propagation rate, pile-soil interaction, and soil disturbance on the pile foundation bearing capacity. This makes the calculation of residual bearing capacity more closely reflect actual working conditions in a marine dynamic environment, resulting in more accurate inversion results. The formula is expressed as follows:

[0058] ,

[0059] in, The design bearing capacity refers to the ultimate vertical or horizontal bearing capacity calculated based on the geological survey report and specifications during the design phase of offshore wind power monopile foundations. Its value is derived from the pile foundation design calculation sheet or construction drawing design documents. Indicates the depth of the pile foundation into the soil; The index represents the nonlinearity of pile-soil interaction, and its value is determined according to any of the following methods: 1. obtained by inversion from field static load tests; 2. obtained by fitting from indoor geotechnical tests; 3. selected according to the empirical value recommended by the foundation code. The soil weakening coefficient is expressed by the formula: , where k represents the soil disturbance sensitivity coefficient, which is obtained by in-situ shear test calibration.

[0060] S3, based on scouring depth and remaining bearing capacity A two-parameter risk assessment criterion is established to determine the current scour risk level; by incorporating the remaining bearing capacity index into scour protection decisions, the risk of misjudgment caused by relying solely on scour depth assessment can be avoided.

[0061] Specifically, the two-parameter risk assessment criterion is as follows:

[0062] Level 1: and , in a steady state;

[0063] Level two: or , in an inhibitory state;

[0064] Level three: or , in a repair state;

[0065] Among them, level three is the highest risk level, and level one is the lowest risk level; represents the safety threshold, , where D is the pile diameter; represents the warning threshold, .

[0066] S4. According to the current scouring risk level, execute the adaptive protection strategy;

[0067] The present invention divides risks into a steady state, an inhibitory state, and a repair state, and different levels are matched with different protection measures, abandoning the traditional one-size-fits-all mode of "full-coverage stone throwing / curing soil": in the steady state, only maintain routine monitoring to avoid ineffective operations; in the inhibitory state, adopt, adopt the placement of flexible flow disturbance units for source inhibition; in the repair state, adopt targeted grouting for precise repair, which not only reduces material waste but also can specifically solve problems in different scouring stages.

[0068] Specifically, the adaptive protection strategy is as follows:

[0069] Steady state: Maintain the routine monitoring frequency, conduct data collection and scouring risk level determination;

[0070] Inhibitory state: Conduct the placement of flexible flow disturbance units; the placement position coordinates of the flexible flow disturbance units are determined by the downstream flow field optimization algorithm;

[0071] In one embodiment, the bottom velocity vector field is extracted at a height of 0.1D from the near-bottom layer, the position of the horseshoe vortex core area caused by the current scouring pit is calculated according to the bottom velocity vector field, the placement position is set 1.5D upstream of the horseshoe vortex core area, and the placement arrangement shape is in a "pin" shape distribution to maximize the dispersion of the bottom boundary layer flow field;

[0072] In one embodiment, the flexible flow disturbance unit is a hydrodynamic flow disturbance component made of a high molecular elastic base material, and its structural form is a strip-shaped or fin-shaped flexible body, with a length of 0.5D–1.2D, and a self-weight anchor block is arranged at the bottom, so that it can swing periodically under the action of the ocean current, thereby destroying the horseshoe vortex structure in front of the pile and reducing the near-bottom flow velocity. Its material is TPU elastomer or rubber composite fabric.

[0073] Repair state: Conduct targeted grouting; the calculation formula for the grouting volume is:

[0074] ,

[0075] in, Indicates the grouting volume; Indicates the fill factor; This represents the projected area of ​​the scour pit. This represents the allowable scour limit depth, which is the critical value for foundation stability. For single pile foundations, it is usually taken as 0.5D. This indicates the seabed elevation at the moment of restoration determination.

[0076] In one embodiment, the targeted grouting uses a fast-setting polymer grouting material.

[0077] S5. After implementing the protection strategy, determine whether the protection is effective. If it is ineffective, automatically upgrade the flushing level and implement the corresponding level of protection strategy. If it is effective, execute S1-S3 for continuous monitoring.

[0078] This invention evaluates the actual effectiveness of protective measures in real time. If the protection is ineffective, it automatically upgrades the scour level and executes a higher-level protection strategy. This solves the problem of no feedback and no adjustment after the implementation of traditional protective measures, and ensures that the protection strategy always adapts to the dynamic development process of scour.

[0079] Specifically, the conditions for determining the effectiveness of protection are: ,in, This represents the threshold for the scour stability criterion, which is the upper limit of the allowable rate of change of scour depth, and its value ranges from 0.001D / h to 0.01D / h. To flush out the stability criterion threshold, this embodiment takes... .

[0080] Example 2

[0081] This embodiment provides an offshore wind turbine foundation scour protection system, which implements the offshore wind turbine foundation scour protection method described in Embodiment 1, including:

[0082] Data acquisition module: used to acquire the seabed elevation field and pile vibration response frequency around the offshore wind turbine monopile foundation in real time;

[0083] Calculation module: used to calculate the scour depth and scour propagation rate based on the seabed elevation field, and obtain the remaining bearing capacity through the structural dynamic inversion model by combining the changes in the vibration response frequency of the pile.

[0084] Risk level assessment module: used to formulate a two-parameter risk assessment criterion based on scour depth and remaining bearing capacity, and determine the current scour risk level;

[0085] Adaptive protection module: Used to execute adaptive protection strategies based on the current scour risk level;

[0086] Protection judgment module: used to determine whether the protection is effective; if ineffective, it automatically upgrades the flushing level and executes the corresponding level of protection strategy; if effective, it performs continuous monitoring.

[0087] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for protecting offshore wind turbine foundations from scour, characterized in that, Includes the following steps: S1. Real-time acquisition of the seabed elevation field and pile vibration response frequency around the offshore wind turbine monopile foundation; S2. Calculate the scour depth based on the seabed elevation field. and scour expansion rate By combining the changes in the vibration response frequency of the pile, the remaining bearing capacity is obtained through a structural dynamic inversion model. The inversion calculation of the remaining bearing capacity introduces a soil weakening coefficient, which is expressed by the following formula: ， in, Indicates the design load-bearing capacity; Indicates the depth of the pile foundation into the soil; This indicates the nonlinearity of pile-soil interaction; The soil weakening coefficient is expressed by the formula: Where k represents the soil disturbance sensitivity coefficient; S3, based on scouring depth and remaining bearing capacity A two-parameter risk assessment criterion is established to determine the current scour risk level; the two-parameter risk assessment criterion is as follows: Level 1: and It is a stable state; Level 2: or , is the suppressed state; Level 3: or It is in a repaired state; in, Indicates the safety threshold. D is the pile diameter; Indicates the warning threshold. ; S4. Execute adaptive protection strategies based on the current scouring risk level; S5. After implementing the protection strategy, determine whether the protection is effective; if ineffective, automatically upgrade the flushing level and implement the corresponding level of protection strategy; if effective, perform continuous monitoring.

2. The method for protecting offshore wind turbine foundations from scour according to claim 1, characterized in that, S1 specifically includes: A multibeam echo sounder array and a vibration sensor array are deployed around the monopile foundation of an offshore wind turbine. The multibeam echo sounder emits a fan-shaped sound beam towards the seabed and receives the echo signal. The depth value of each measuring point is calculated based on the sound wave propagation time, resulting in a discrete depth measuring point set. A continuous seabed elevation function is constructed from the discrete depth measuring point set through spatial interpolation, yielding the seabed elevation field. The real-time seabed elevation function is denoted as […]. The vibration response frequency of the pile is collected by a vibration sensor.

3. The method for protecting offshore wind turbine foundations from scour according to claim 1, characterized in that, In S2, the scour depth is obtained by calculating the difference between the initial unscourized reference seabed elevation and the currently measured lowest point seabed elevation. The formula is as follows: ， in, Indicates the depth of scouring; This indicates the initial, un-scoured baseline seabed elevation; Indicates the current time The seabed elevation at the lowest point was measured.

4. The method for protecting offshore wind turbine foundations from scour according to claim 1, characterized in that, The scouring expansion rate mentioned in S2 is determined based on the rate of change of scouring volume with time, and the formula is expressed as follows: ， in, Indicates the scouring and spreading rate; Indicates the area of ​​the scour pit; Represents the seabed elevation field; This represents a small area element.

5. A method for protecting offshore wind turbine foundations from scour according to claim 4, characterized in that, S4's adaptive protection strategy is as follows: Steady state: Maintain regular monitoring frequency, collect data, and determine the risk level of erosion. Suppression state: Deploy flexible flow disturbance units; the deployment coordinates of the flexible flow disturbance units are determined by the lower flow field optimization algorithm; Repair state: Targeted grouting is performed; the formula for calculating the grouting volume is: ， in, Indicates the grouting volume; Indicates the fill factor; This represents the projected area of ​​the scour pit. Indicates the maximum permissible scouring depth; This indicates the seabed elevation at the moment of restoration determination.

6. The method for protecting offshore wind turbine foundations from scour according to claim 1, characterized in that, The conditions for determining the effectiveness of protection in S5 are: ,in, This represents the threshold for the scour stability criterion.

7. A scour protection system for offshore wind turbine foundations, implementing the scour protection method for offshore wind turbine foundations as described in claim 1, characterized in that, include: Data acquisition module: used to acquire the seabed elevation field and pile vibration response frequency around the offshore wind turbine monopile foundation in real time; Calculation module: used to calculate the scour depth and scour propagation rate based on the seabed elevation field, and obtain the remaining bearing capacity through the structural dynamic inversion model by combining the changes in the vibration response frequency of the pile. Risk level assessment module: used to formulate a two-parameter risk assessment criterion based on scour depth and remaining bearing capacity, and determine the current scour risk level; Adaptive protection module: Used to execute adaptive protection strategies based on the current scour risk level; Protection judgment module: used to determine whether the protection is effective; if ineffective, it automatically upgrades the flushing level and executes the corresponding level of protection strategy; if effective, it performs continuous monitoring.

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