Offshore wind turbine single pile foundation porous sinkable truncated cone scour protection device and protection effect prediction method
Patent Information
- Application Number
- CN202610103650.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-26
- Publication Date
- 2026-06-19
Smart Images
Figure CN122236155A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of local scour suppression technology for offshore wind turbine foundations, specifically to a scour protection device for multi-hole settleable frustum foundations of offshore wind turbines and a method for predicting the protection effect. Background Technology
[0002] Currently, the foundation types for offshore wind turbines are becoming increasingly diversified, mainly including monopile foundations, gravity foundations, multipile foundations, jacket foundations, and floating foundations. Among these, monopile foundations, due to their significant advantages such as simple structure, convenient installation, and low splicing difficulty, have become the preferred foundation type for constructing large near-shore wind turbines worldwide and are widely used in global offshore wind power projects. However, with the large-scale advancement and long-term service of coastal wind power projects, the inherent technical challenges of monopile foundations are gradually becoming apparent. During the service life of a monopile offshore wind turbine, the presence of the monopile foundation significantly disrupts the surrounding local flow field, leading to substantial bed shear stress caused by water flow and eddies around the foundation, which in turn triggers continuous scouring of the seabed soil around the monopile foundation. This scouring phenomenon continuously reduces the foundation depth, impairs the cooperative working performance between the foundation and the soil, and in severe cases, may lead to major safety accidents such as turbine collapse and exposure of submarine cables, posing a serious threat to the long-term stable operation of wind power equipment. According to Whitehouse (2011), the maximum scour depth around a large-diameter monopile foundation can reach 1.38 times the diameter of the monopile. This data fully reveals the fatal impact of scour on the safe operation of wind turbines.
[0003] To mitigate the potential risks posed by localized scour, various conventional protective measures have been developed in the engineering field, such as riprap, sand blankets, sandbags, and interlocking concrete embankments. While these measures offer flexibility in material availability, they generally suffer from low construction precision, inconsistent scour-prevention effects, and the protective materials are easily washed away by water flow. This not only fails to provide long-term protection but may also trigger secondary scour, requiring significant manpower and resources for regular maintenance, leading to high project maintenance costs. Furthermore, soil stabilization, as a targeted measure, aims to prevent scour by modifying the properties of silt. However, this technology suffers from drawbacks such as large-scale filling and high engineering costs, and its long-term durability has not been fully verified in engineering practice, severely limiting its application. More critically, the design of existing protective measures largely relies on engineering experience for selection, lacking a design tool that quantitatively correlates protective structural parameters, on-site hydraulic conditions, and the final protective effect. This results in either overly conservative designs, wasting engineering resources and reducing economic efficiency, or improperly matched protective parameters that fail to achieve the expected protective effect, making it difficult to meet the dual safety and economic requirements of offshore wind power projects.
[0004] Meanwhile, many early-built offshore wind turbine monopile foundations lacked effective scour protection devices due to technical limitations or design oversights during construction. Over time, the scour of seawater has created large scour pits around these foundations, significantly reducing the foundation depth and exposing submarine cables. This not only severely weakens the structural stability of the foundations but also significantly shortens the lifespan of the turbines, posing a significant threat to the safe operation of offshore wind power projects. Summary of the Invention
[0005] The purpose of this invention is to provide a multi-hole, settleable truncated cone scour protection device for offshore wind turbine monopile foundations and a method for predicting the protection effect, thereby solving the problems of poor effectiveness, insufficient economy, and lack of quantitative basis in the design of existing protection measures.
[0006] To achieve the above objectives, the technical solution of this application is: a multi-hole, settleable frustum scour protection device for offshore wind turbine monopile foundations, comprising: The frustum-shaped protective component is fitted onto the outside of the monopile foundation. Its top inner diameter is matched with the outer diameter of the monopile foundation. When the lower end is suspended due to scouring, it falls back onto the sand surface by its own weight, forming a self-adjusting settlement state that continuously covers the protected area. Multiple support rods are provided and evenly distributed. They are fixed to the top of the inner side of the frustum-shaped protective component. Their length is less than the height of the frustum-shaped protective component. They play a supporting and limiting role during the settlement of the protective component and prevent the frustum-shaped protective component from tilting or shifting. The energy dissipation sand inlet holes are multiple and evenly distributed on the surface of the frustum-shaped protective component. They can reduce the energy of the incoming flow, change the flow velocity, promote the deposition of sediment in the ocean current, and allow the sediment to enter the interior of the protective component to replenish the sand, thereby enhancing the stability of the monopile foundation.
[0007] In another implementation of the present invention, the inner diameter of the top surface of the frustum-shaped protective member is 5-15 cm larger than the outer diameter of the single pile foundation.
[0008] In another embodiment of the present invention, the angle between the generatrix of the frustum of the protective member and the vertical axis is 30°-60°.
[0009] In another implementation of the present invention, the height of the frustum-shaped protective member is 1-2 times the diameter of the single pile foundation.
[0010] In another implementation of the present invention, the diameter of the energy dissipation sand inlet hole is 5-20 cm.
[0011] In another implementation of the present invention, the opening ratio of the energy dissipation sand inlet hole is 0 to 30%, and the opening ratio is the ratio of the permeable area of the hole to the surface area of the frustum.
[0012] The present invention also provides the application of the above-mentioned porous settling frustum scour protection device for offshore wind turbine monopile foundations in the repair and protection of offshore monopile wind turbine foundations that have been partially scoured.
[0013] This invention also provides a method for predicting the protective effect of the above-mentioned porous settleable truncated cone scour protection device for a single pile foundation of an offshore wind turbine. The method uses a scour depth prediction approach to obtain the maximum scour depth around the pile. The scour depth prediction approach is as follows: in, S This represents the maximum scour depth around the pile. D The diameter of a single pile; H The height of the frustum-shaped protective component; α The angle between the generatrix of the frustum and the vertical axis; P Open area ratio; α 0 represents the tilt angle; A , B , C , K This is an empirical coefficient.
[0014] In another implementation of the present invention, the self-settlement stability of the protective device is verified based on the soil mechanics foundation ultimate bearing capacity theory. The most unfavorable working condition is the formation of the maximum unsupported width on the flow-facing side of the bottom surface under the action of unilateral water flow. B s The weight of the device G From the remaining effective base area A eff Bearing, when average contact pressure p = G / A eff Reaching the ultimate bearing capacity of seabed soil q u At that time, the device began to sink.
[0015] In another implementation of the present invention, the critical condition for self-settlement is: in, G For the weight of the protective device, , ρ m The material density of the frustum-shaped protective component; g It is the acceleration due to gravity; V shell The effective volume of the frustum-shaped protective housing; V struts This refers to the total volume of the internal support rods; A eff This refers to the effective supporting bottom area after scouring and suspension. γ′ represents the effective unit weight of seabed soil; B eff This is the equivalent width of the remaining annular support surface. B eff =( D o - D i ) / 2, D o and D i These refer to the outer diameter and inner diameter of the bottom surface of the frustum-shaped protective component, respectively. N γ It is a dimensionless bearing capacity coefficient of the foundation, which is only related to the internal friction angle of the soil.
[0016] By adopting the above technical solution, the present invention can achieve the following technical effects: 1. The frustum-shaped protective component of the present invention directly covers the key area around the pile, which can effectively block the direct scouring of the soil around the pile by the ocean current, reducing scouring and erosion from the source; at the same time, the energy dissipation and sand inlet holes evenly distributed on the surface of the protective component can efficiently reduce the scouring energy of the water flow, reduce the sand carrying capacity of the ocean current, promote the deposition of sediment in the area around the pile, realize active sand replenishment, increase the foundation burial depth, and systematically improve the stability and bearing capacity of the wind turbine foundation.
[0017] 2. The inner diameter of the top surface of the frustum-shaped protective component is adapted to the outer diameter of the monopile foundation. When the seabed level drops and the lower end of the protective component is suspended, it can fall back onto the sand surface by its own weight, forming a self-adjusting state of settlement. This ensures that the protected area is always in contact with the seabed, avoiding the problem of traditional protective measures failing due to scouring and suspension. Combined with the self-settling stability verification method based on the ultimate bearing capacity theory of the foundation, it provides rigorous theoretical support and design guarantee for the adaptive settlement of the protective device, ensuring the structural reliability during long-term service.
[0018] 3. This invention establishes a quantitative prediction model between scour depth and the core structural parameters of the protective device. It can predict the protective effect and optimize the structural parameters based on specific hydrological and sediment conditions, overcoming the drawbacks of traditional protective measures that rely on experience for selection, are conservative in design, or fail to meet the required standards. The device has both anti-scour and siltation functions, and is not only suitable for scour prevention of newly built offshore wind turbine foundations, but also for repairing and reinforcing existing foundations with scour pits through sand replenishment deposition. It solves the technical problems of poor adaptability and unclear effects of traditional protective measures in repair projects.
[0019] 4. The protective device consists only of a frustum-shaped protective component, an internal support rod, and an energy-dissipating sand inlet hole. Its structure is simple and the manufacturing process is easy. Offshore installation does not require complex equipment or complicated procedures, making construction convenient and efficient. This significantly reduces the cost and difficulty of project implementation, while also reducing the frequency and cost of subsequent maintenance. It combines advanced technology with good economic efficiency and is suitable for large-scale promotion and application. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0021] Figure 1 Structural diagram of a perforated, settleable frustum-shaped scour protection device for a monopile foundation of an offshore wind turbine. Figure 2 A front view of a perforated, settleable frustum-shaped scour protection device for a monopile foundation of an offshore wind turbine. Figure 3 Top view of the scour protection device for a multi-hole, settleable frustum-shaped monopile foundation of an offshore wind turbine. Figure 4 A bottom view of the scour protection device for a multi-hole, settleable frustum-shaped monopile foundation of an offshore wind turbine. Figure 5 Diagram showing the setup for a physical experiment on localized scour of a monopile wind turbine foundation; Figure 6 Topographic map showing localized scour of a monopile wind turbine foundation; Figure 7 Figure showing the results of a physical experiment on the erosion protection of a small-sized frustum-shaped protective component. Figure 8 Figure showing the results of a physical experiment on the erosion protection of a large-sized frustum-shaped protective component. The numbers in the diagram are explained as follows: 1. Frustum-shaped protective component; 2. Support rod; 3. Energy dissipation sand inlet hole; 4. Monopile foundation; 5. Test section sand bed; 6. Gentle slope; 7. ADV current meter; 8. Laser topographic scanner. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.
[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0024] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.
[0025] Example 1 This embodiment provides a multi-hole, settleable truncated cone scour protection device for a single pile foundation of an offshore wind turbine, which includes a truncated cone-shaped protective component 1, a support rod 2, and an energy-dissipating sand inlet hole; The frustum-shaped protective component 1 is integrally machined into a frustum shape. Based on the outer diameter of the monopile foundation 4 to be protected, its top inner diameter is set to be 5-15 cm larger than the outer diameter of the monopile foundation 4, preferably 10 cm, to ensure the protective component can be smoothly installed and to allow for settlement adjustment gaps. In this embodiment, the diameter of the monopile foundation 4 is set to D=5m, and the height of the frustum-shaped protective component 1 is determined to be 1-2 times the diameter of the monopile foundation, preferably 1.2D=6m. The angle between the generatrix of the frustum and the vertical axis is set to 30°-60°, preferably 50° in this embodiment.
[0026] The support rod 2 is made of steel and is evenly distributed around the top of the inner side of the frustum-shaped protective component 1. It can be fixed to the inner wall of the protective component by welding. In this embodiment, the length of the support rod 2 is set to 5m, which is less than the height of the frustum-shaped protective component 1 (6m), so as to achieve the function of supporting and preventing tilting during settlement.
[0027] The energy-dissipating sand inlet holes 3 are evenly distributed on the side of the frustum-shaped protective component 1, with a diameter of 5-20 cm. In this embodiment, the diameter is preferably 15 cm, taking into account the ocean current conditions of the target sea area. The opening ratio is designed to be 0-30%, and in this embodiment, it is preferably 18%. The opening ratio is calculated as the ratio of the water-permeable area of the hole to the surface area of the frustum side.
[0028] The assembly method of the above device is as follows: the prepared support rod 2 is fixed to the top of the inner side of the frustum-shaped protective component 1 to ensure a firm connection and form a complete protective device body; the protective device is hoisted to the target monopile foundation 4 using offshore crane equipment, and slowly lowered so that the frustum-shaped protective component 1 is fitted onto the outside of the monopile foundation 4 until the bottom of the protective component is in contact with the seabed surface, thus completing the installation.
[0029] Settlement-type self-adjustment: When the seabed around the monopile foundation 4 is eroded, causing the lower end of the frustum-shaped protective component 1 to be suspended, the protective device relies on its own weight to slowly fall back to the sand surface along the outside of the monopile foundation 4, forming a settlement-type self-adjustment state, always maintaining the coverage and protection of the soil around the pile, and avoiding failure due to the bottom being suspended.
[0030] Energy dissipation and sand replenishment: When the ocean current flows through the protective device, the energy dissipation sand inlet 3 reduces the energy of the water flow, changes the flow velocity, and reduces the sand carrying capacity of the ocean current, causing floating mud and sand particles in the ocean current to be deposited around the pile; on the other hand, the mud and sand enter the interior of the frustum-shaped protective component 1 through the energy dissipation sand inlet 3 to be deposited, thereby achieving the sand replenishment function, increasing the burial depth of the single pile foundation 4, and enhancing the stability of the wind turbine foundation.
[0031] Anti-tilt support: When the frustum-shaped protective component 1 settles, the support rod 2 fits against the outer side of the single pile foundation 4, which plays a supporting and limiting role, preventing the protective component from tilting and ensuring the overall stability of the structure.
[0032] Example 2 This embodiment applies the porous, settleable frustum-shaped scour protection device for offshore wind turbine monopile foundations described in Embodiment 1 to the repair and protection of offshore monopile wind turbine foundations that have already experienced localized scour. The specific implementation is as follows: A monopile foundation 4 in the target offshore wind farm has been in service for many years without initial scour protection. Scour pits of a certain size have formed around the pile, resulting in a significant reduction in the burial depth of the monopile foundation 4 and exposed and suspended wind turbine cables, which seriously affects the safety and service life of the wind turbine. It is necessary to repair and protect it using the device of this invention.
[0033] Based on the actual diameter of the monopile foundation 4, the inner diameter of the top surface of the frustum-shaped protective component 1 is adjusted to be 8 cm larger than the outer diameter of the monopile foundation 4. Considering the scale of the scour pit and the ocean current conditions, the height of the frustum-shaped protective component 1 is set to 1.5 times the diameter of the monopile foundation, the angle between the generatrix of the frustum and the vertical axis is 45°, the diameter of the energy dissipation sand inlet hole 3 is 12 cm, the opening rate is 20%, and four support rods 2 are set, with a length less than the height of the frustum.
[0034] The adapted protective device is hoisted onto the target monopile foundation 4 using offshore crane equipment, and then slowly lowered so that the frustum-shaped protective component 1 is fitted onto the outside of the monopile foundation 4, with its bottom resting on the sand bed surface at the edge of the scour pit, thus completing the installation.
[0035] After installation, when the ocean current flows through the frustum-shaped protective component 1, the evenly distributed energy-dissipating sand inlet holes 3 change the incoming flow velocity, reducing the current's ability to carry sediment, causing the sediment carried by the current to deposit in the scour pit. Simultaneously, sediment continuously enters the protective component through the energy-dissipating sand inlet holes 3, accumulating in the scour pit area around the monopile foundation 4, gradually filling the original scour pit and achieving the sand replenishment function. As sediment continues to deposit, the burial depth of the monopile foundation 4 gradually increases, the original scour pit is continuously repaired, and finally a stable sand bed protective layer is formed, enhancing the stability of the wind turbine foundation and solving the problem of exposed cables.
[0036] Example 3 This embodiment predicts the protective effect of the protective device based on the quantitative prediction model established by the present invention. Specifically, the maximum scour depth around the pile is obtained by predicting the scour depth, and the formula is as follows: in, S This represents the maximum scour depth around the pile. D The diameter of a single pile; H The height of the frustum-shaped protective component; α The angle between the generatrix of the frustum and the vertical axis; P The open area ratio (%) is the proportion of the area of the energy dissipation sand inlet hole to the surface area of the frustum. α 0 = 30° (reference tilt angle); A , B , C , K These are empirical coefficients, determined based on experimental fitting, and based on the experimental data of this invention. A = 2.056, B = -0.386, C = -0.0233, K = -3.18.
[0037] The specific prediction steps include: Step 1: Collect basic parameters, including the diameter D of the single pile foundation 4, the height H of the frustum-shaped protective component 1, and the angle between the generatrix of the frustum and the vertical axis. α The opening rate P of the energy dissipation sand inlet hole 3 was determined, and the hydraulic conditions of the target sea area were also clarified. θ / θ cr value).
[0038] Step 2: Verify the model's applicability and confirm that the structural parameters satisfy 0.67 ≤ H / D ≤2.0, 30°≤ α ≤60°, 0≤ p ≤25%, hydraulic conditions met θ / θ cr≤3.2; For higher flow velocities or more complex flow, the applicable range needs to be expanded by adjusting the coefficient.
[0039] Step 3: Parameter substitution calculation. Substitute the collected parameters into the above formula to obtain the maximum scour depth S around the pile, which is the predicted value of the protective effect of the protective device.
[0040] To verify the effectiveness of the device and prediction method of this invention, physical experiments were conducted in the O-Tube experimental device of the State Key Laboratory of Coastal and Offshore Engineering at Dalian University of Technology, as follows: The O-Tube experimental tank is 30m long and 1.5m wide, with the experimental section located in the middle of the tank, totaling 10m in length. In the core experimental section, the sand bed 5 is 0.6m high and 6m long, and is covered with washed quartz sand; upstream and downstream of the core experimental section, 0.2m thick and 2.0m long layers of sediment are laid to ensure sufficient sediment replenishment in the direction of the incoming flow; a 1:15 gentle slope 6 is set at both ends of the experimental section to ensure a smooth transition of the incoming flow to the core experimental section.
[0041] The single pile foundation 4 is made of a smooth organic glass tube with a diameter of D=0.15m. A frustum-shaped protective component 1 is fitted on the outside of the single pile foundation 4. The water depth is set to 0.9m.
[0042] The experimental coordinate system is defined as follows: the horizontal direction is the y-axis, the initial water flow direction is the positive y-axis direction, the water depth direction is the z-axis, the zero point is located on the initial sand bed plane, and the direction from the bottom of the water to the water surface is the positive z-axis direction.
[0043] Testing equipment: The ADV flow velocity outside the boundary layer is measured in real time using an ADV flow meter 7, and the laser topographic scanner 8 is used to measure the scour depth and scour extension range around the monopile foundation 4 in real time.
[0044] The experiment adopted the similarity criterion of water flow intensity. Based on the on-site hydrological conditions, the average flow velocity of the cross section was calculated to be 0.55 m / s, and the period was 2 hours. Under this flow velocity, the shear stress on the sand bed in the experimental section was about 3.15 times the critical starting shear stress, and the scour type was moving bed scour.
[0045] Three sets of experiments were conducted: no protection, protection with small-sized frustum protective devices, and protection with large-sized frustum protective devices. The scouring effect was compared and analyzed.
[0046] Unprotected group: by Figure 6 It can be seen that the scour pit formed around the single pile foundation 4 has a depth of nearly twice the diameter, which has a significant negative impact on the bearing capacity of the pile foundation and the surrounding cables.
[0047] Small-sized protective component group: A frustum-shaped protective component 1 with a frustum inclination angle (angle between the generatrix and the vertical axis) of 30°, a frustum height of 0.67D, and an opening ratio of 10% was used. Experimental results are as follows: Figure 7The data shows that the maximum scour depth around the pile has decreased by 36.7%, and the edge of the scour pit is no longer steep, which has achieved a certain protective effect.
[0048] Large-size protective component group: A frustum-shaped protective component 1 with a frustum inclination angle of 60°, a frustum height of 1D, and an opening ratio of 20% was used. The experimental results are as follows. Figure 8 The data shows that there is almost no scouring around the pile, and significant sand accumulation on the rear side forms a stable protective layer, with excellent sand replenishment and protection effects.
[0049] Input design conditions: Single pile foundation diameter D = 5.0 m; Hydrological conditions: Design flow velocity U = 1.0 m / s, water depth h = 15 m; Seabed sediment is medium to fine sand, median particle size d50 = 0.3 mm, internal friction angle ϕ = 32°, effective unit weight γ` = 9.0 kN / m³ 3 The protection target is the maximum scour depth S around the pile. target ≤0.4×1.8D=3.6m.
[0050] Parameter optimization: The key parameters were determined by iterative calculation using the scour depth prediction formula: frustum height H / D = 1.2, frustum inclination angle. α =50°, opening ratio P=18%, substituting into the formula, the predicted scour depth S≈3.3m. S ≤ S target Meets the protection objectives.
[0051] Self-settlement stability verification: The protective device is determined to be a reinforced concrete structure (wall thickness 0.25m). The self-settlement threshold condition p≥qu is verified. The result meets the requirements, indicating that the device can reliably sink under its own weight when suspended by scour, thus achieving self-adaptive adjustment.
[0052] Design output: The final parameters of the protective device are determined as follows: height of the truncated cone H / D=1.2, inclination angle of the truncated cone α=50°, opening ratio P=18%, and wall thickness 0.25m. After application, the maximum scour depth around the pile can be suppressed to about 3.35m, and it has self-settling stability.
[0053] The above experiments and engineering examples clearly verify the protective and repair effects of the device of the present invention, the accuracy of the prediction method, and the scientific nature of the design process. It can be applied to engineering practice and has important reference significance and engineering value for the scour protection of offshore monopile wind turbine foundations and the treatment of existing scour pits.
[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A multi-hole, settleable frustum scour protection device for offshore wind turbine monopile foundations, characterized in that, include: The frustum-shaped protective component (1) is fitted on the outside of the single pile foundation (4). Its top inner diameter is matched with the outer diameter of the single pile foundation (4). When the lower end is suspended due to scouring, it falls back to the sand surface by its own weight, forming a settlement self-adjustment state, and continuously covers the protected area. Support rods (2) are provided in multiple evenly distributed positions and are fixed to the top of the inner side of the frustum-shaped protective component (1). Their length is less than the height of the frustum-shaped protective component (1). They play a supporting and limiting role during the settlement of the protective component and prevent the frustum-shaped protective component (1) from tilting or shifting. The energy dissipation sand inlet holes (3) are provided in multiple and evenly distributed on the surface of the frustum-shaped protective component (1). They can reduce the energy of the incoming flow, change the flow velocity of the water, promote the deposition of sediment in the ocean current, and allow the sediment to enter the interior of the protective component to replenish the sand, thereby enhancing the stability of the single pile foundation (4).
2. The scour protection device for a multi-hole, settleable frustum-shaped foundation of an offshore wind turbine according to claim 1, characterized in that, The inner diameter of the top surface of the frustum-shaped protective component (1) is 5-15 cm larger than the outer diameter of the single pile foundation.
3. The scour protection device for a multi-hole, settleable frustum foundation of an offshore wind turbine according to claim 1, characterized in that, The angle between the generatrix of the frustum-shaped protective component (1) and the vertical axis is 30°-60°.
4. The scour protection device for a multi-hole, settleable frustum foundation of an offshore wind turbine according to claim 1, characterized in that, The height of the frustum-shaped protective component (1) is 1-2 times the diameter of the single pile foundation (4).
5. The scour protection device for a multi-hole, settleable frustum-shaped foundation of an offshore wind turbine according to claim 1, characterized in that, The diameter of the energy dissipation sand inlet (3) is 5-20 cm.
6. The scour protection device for a multi-hole, settleable frustum foundation of an offshore wind turbine according to claim 1, characterized in that, The opening rate of the energy dissipation sand inlet hole (3) is 0 to 30%, and the opening rate is the ratio of the permeable area of the hole to the side surface area of the frustum.
7. The application of the porous, settleable truncated cone scour protection device for offshore wind turbine monopile foundations as described in any one of claims 1-6 in the repair and protection of offshore monopile wind turbine foundations that have experienced localized scour.
8. A method for predicting the protective effect of the porous, settleable frustum-shaped scour protection device for a monopile foundation of an offshore wind turbine as described in any one of claims 1-6, characterized in that, The maximum scour depth around the pile is obtained using a scour depth prediction method, which is as follows: in, S This represents the maximum scour depth around the pile. D The diameter of a single pile; H The height of the frustum-shaped protective component; α The angle between the generatrix of the frustum and the vertical axis; P Open area ratio; α 0 represents the tilt angle; A , B , C , K This is an empirical coefficient.
9. The method for predicting the protective effect of the porous, settleable truncated cone scour protection device for offshore wind turbine monopile foundations according to claim 8, characterized in that, The self-settlement stability of the protective device is verified based on the ultimate bearing capacity theory of soil mechanics foundation. The most unfavorable working condition is the formation of the maximum unsupported width on the flow-facing side of the bottom surface under the action of unilateral water flow. B s The weight of the device G From the remaining effective base area A eff Bearing, when average contact pressure p = G / A eff Reaching the ultimate bearing capacity of seabed soil q u At that time, the device began to sink.
10. The method for predicting the protective effect of the porous, settleable truncated cone scour protection device for offshore wind turbine monopile foundations according to claim 9, characterized in that, The critical condition for self-settlement is: in, G For the weight of the protective device, , ρ m The material density of the frustum-shaped protective component; g It is the acceleration due to gravity; V shell The effective volume of the frustum-shaped protective housing; V struts This refers to the total volume of the internal support rods; A eff This refers to the effective supporting bottom area after scouring and suspension. γ ′ represents the effective unit weight of seabed soil; B eff This is the equivalent width of the remaining annular support surface. B eff =( D o - D i ) / 2, D o and D i These refer to the outer diameter and inner diameter of the bottom surface of the frustum-shaped protective component, respectively. N γ It is a dimensionless bearing capacity coefficient of the foundation, which is only related to the internal friction angle of the soil.