Offshore wind power foundation scouring protection method and system

Abstract

The invention relates to an offshore wind power foundation scouring protection method and system, and belongs to the technical field of offshore wind power protection. The method comprises the following steps: through a multi-beam depth sounding sonar array and a vibration sensor array, obtaining a seabed elevation field and a pile body vibration response frequency around the offshore wind power single pile foundation in real time; the scouring depth and the scouring expansion rate are calculated based on a seabed elevation field, and the pile foundation residual bearing capacity is obtained through a structural dynamic inversion model in combination with pile body vibration response frequency changes; then, a two-parameter risk judgment criterion is constructed according to the scouring depth and the residual bearing capacity, and three-level scouring risk levels of a stable state, a development state and a dangerous state are divided; then, an adaptive protection strategy is executed according to the risk level, conventional monitoring is maintained in a stable state, a flexible turbulent flow unit is put in a development state, and targeted grouting is implemented in a dangerous state; and finally verifying the protection effect, upgrading the protection level if the protection effect is invalid, and continuously and circularly monitoring if the protection effect is valid. The precision and efficiency of scouring protection can be improved.

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: This invention provides a method for protecting offshore wind turbine foundations from scour, comprising 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. ; 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. 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.

[0005] 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; 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.

[0006] 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: , 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.

[0007] 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: , 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.

[0008] 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: , 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.

[0009] Furthermore, the two-parameter risk assessment criterion described in S3 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; 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. .

[0010] Furthermore, 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 depth of scouring; This indicates the seabed elevation at the moment of restoration determination.

[0011] 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.

[0012] 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: 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.

[0013] The advantages of this invention are: 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

[0014] 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.

[0015] Figure 1 This is a flowchart of the steps of the method of the present invention. Detailed Implementation

[0016] 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.

[0017] Example 1 In this embodiment, as Figure 1As shown, this invention provides a method for protecting offshore wind turbine foundations from scour, the specific steps of which include: S1. Real-time acquisition of the seabed elevation field and pile vibration response frequency around the offshore wind turbine monopile foundation; 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.

[0018] 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. ; 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. 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: , 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.

[0019] The scour propagation rate is determined based on the rate of change of scour volume over time, expressed by the following formula: , 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.

[0020] 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: , 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.

[0021] 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. Specifically, 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; 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. .

[0022] S4. Execute adaptive protection strategies based on the current scouring risk level; This invention classifies risks into stable, suppressed, and remedial states, matching different levels with differentiated protective measures, abandoning the traditional one-size-fits-all approach of "full coverage rock dumping / solidification": in the stable state, only routine monitoring is maintained to avoid ineffective operations; in the suppressed state, flexible turbulence units are deployed for source suppression; and in the remedial state, targeted grouting is used for precise repair, which reduces material waste and can address the problems at different stages of scour.

[0023] Specifically, the adaptive protection strategy is as follows: Steady state: Maintain regular monitoring frequency, collect data, and determine the risk level of erosion. Inhibited state: Deploy flexible spoiler units; the deployment position coordinates of the flexible spoiler units are determined by a downstream flow field optimization algorithm; In one embodiment, the bottom velocity vector field is extracted at a height of 0.1D near the bottom layer, the position of the horseshoe vortex core area caused by the current scouring pit is calculated based on the bottom velocity vector field, the deployment position is set at 1.5D upstream of the horseshoe vortex core area, and the deployment arrangement shape is in a "pin" shape distribution to maximize the disruption of the bottom boundary layer flow field; In one embodiment, the flexible spoiler unit is a hydrodynamic spoiler 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 anchoring block is arranged at the bottom, so that it can generate periodic swinging under the action of ocean currents, thereby destroying the horseshoe vortex structure in front of the pile and reducing the near-bottom flow velocity. Its material is a TPU elastomer or a rubber composite fabric.

[0024] Repair state: Perform targeted grouting; the calculation formula for the grouting volume is: , where, represents the grouting volume; represents the filling coefficient; represents the planar projection area of the scouring pit; represents the allowable scouring limit depth, which is the critical value of foundation stability, and usually takes 0.5D for a single pile foundation; represents the seabed elevation at the moment of repair state determination.

[0025] In one embodiment, the targeted grouting uses a quick-setting high molecular polymer grouting material. <000018​​​​​​​​​​​​​​​​​​​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: 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.

[0029] 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 of scour protection for an offshore wind power foundation, c h a r a c t e r i s e d 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 from the seabed elevation field and the rate of scour propagation , combined with the change of pile vibration response frequency, to obtain the residual bearing capacity through the structural dynamic inversion model ; S3, based on scouring depth and remaining bearing capacity Establish a two-parameter risk assessment criterion to determine the current scour risk level; 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. The method for protecting offshore wind turbine foundations from scour according to claim 1, characterized in that, The inversion calculation of the remaining bearing capacity described in S2 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 represents the nonlinear index of pile-soil interaction; The soil weakening coefficient is expressed by the formula: , where k represents the soil disturbance sensitivity coefficient.

6. The method for protecting offshore wind turbine foundations from scour according to claim 1, characterized in that, The two-parameter risk assessment criterion described in S3 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. .

7. A method for protecting offshore wind turbine foundations from scour according to claim 6, 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.

8. 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.

9. A scour protection system for offshore wind turbine foundations, comprising 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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