Scouring protection structure for offshore wind turbine foundation and optimization method of scouring protection structure

Abstract

The invention relates to the technical field of ocean engineering, and discloses a scour protection structure for an offshore wind turbine foundation and an optimization method of the scour protection structure. The scour protection structure for the offshore wind turbine foundation comprises the pile foundation, the installation sleeve and the artificial fish reef, and the retainer is arranged on the sleeve installed on the pile foundation, so that the fish reef body can be limited to move in the direction away from the pile foundation. Namely, by arranging the stop piece comprising the limiting plate and the stop side plate, the stop side plate extends into the inhabiting cavity of the fish reef body and abuts against the inner wall of the inhabiting cavity, reliable limiting is formed, the degree of freedom of the artificial fish reef relative to the mounting sleeve and the pile foundation in the horizontal direction is directly limited, and failure displacement of the fish reef body relative to the pile foundation is prevented. The scour protection structure provided by the invention forms a reliable technical scheme for fusion development of an offshore wind plant and a marine ranch, and compared with a traditional artificial fish reef, the scour protection structure can avoid the problems of displacement and dislocation under the action of hydrodynamic loads such as long-term waves and ocean currents.

Description

Technical Field

[0001] The present invention relates to the field of marine engineering technology, and in particular to a scour protection structure for an offshore wind turbine foundation and an optimization method thereof. Background Art

[0002] With the growing demand for comprehensive utilization of marine resources, the integrated development model of offshore wind power and marine ranching has become a key direction for the development of the marine economy. This model uses offshore wind farms to power aquaculture facilities and uses artificial reefs to optimize marine habitats, achieving synergistic benefits in energy production, ecological restoration, and fishery enhancement.

[0003] In existing integrated development practices, artificial reefs are often deployed in the waters surrounding wind turbine foundations to create ecological barriers. Traditional artificial reefs often utilize standardized prefabricated structures, such as box-shaped concrete frames or steel cylinders, with hollow interiors for marine life. These structures are secured to the seabed via anchors or counterweights and combined with aquaculture cages and algae cultivation ropes to form aquaculture units.

[0004] However, in actual application, it was found that traditional artificial reefs are prone to structural scouring and instability when encountering complex hydrodynamic environments (including currents, waves and tidal effects) after being deployed. Their insufficient resistance to water flow impact causes the artificial reefs to shift under long-term hydrodynamic loads, eventually leaving the preset installation position, affecting the overall stability of the reef group. Summary of the Invention

[0005] In view of this, the present invention provides a scour protection structure for an offshore wind turbine foundation and an optimization method thereof, so as to solve the problem of displacement of artificial reefs under long-term hydrodynamic loads.

[0006] In a first aspect, the present invention provides a scour protection structure for an offshore wind turbine foundation, comprising a mounting sleeve, an artificial reef, and a stopper. The mounting sleeve is sleeved and mounted on a pile foundation. The artificial reef includes a reef body, the inner wall of which forms a habitat chamber with the seabed. The stopper includes a stopper plate and a stopper side plate. One end of the stopper plate along its length is connected to the outer wall of the mounting sleeve, while the other end of the stopper plate along its length extends through the reef body and into the habitat chamber. The stopper side plate is mounted to the other end of the stopper plate along its length and is configured to abut the inner wall of the reef body.

[0007] Beneficial effect: By setting a stopper, the fish reef body is restricted from moving in the direction away from the pile foundation. Specifically, by setting a stopper comprising a limit plate and a stop side plate, and extending the stop side plate into the habitat chamber of the fish reef body and abutting against its inner wall, a reliable limit is formed, which can directly limit the horizontal freedom of the artificial fish reef relative to the installation sleeve and the pile foundation, and prevent the fish reef body from failing and displacing relative to the pile foundation. The scour protection structure provided by the present invention forms a reliable technical solution for the integrated development of offshore wind farms and marine ranches, and compared with traditional artificial fish reefs, it can avoid the problems of displacement and dislocation under the action of long-term hydrodynamic loads such as waves and currents.

[0008] In an optional embodiment, the fish reef body is provided with multiple rows of centering hole groups, which are spaced apart along the central axis of the annular contact end face, and each row of the centering hole groups is provided with multiple centering holes arranged in a circular array around the central axis of the annular contact end face.

[0009] In an optional embodiment, the centering holes in two adjacent rows of the centering hole groups are arranged in a circumferentially staggered manner.

[0010] In an optional embodiment, the fish reef body is a hemispherical shell, the annular contact end surface of the hemispherical shell is in contact with the seabed surface, and the arc-shaped wall of the hemispherical shell is in contact with the seawater; the artificial fish reef also includes a bottom plate, which is installed on the annular contact end surface.

[0011] In an optional embodiment, a plurality of the artificial fish reefs are provided, and the plurality of artificial fish reefs are arranged in a circular array around the central axis of the installation sleeve.

[0012] In an optional embodiment, a drain hole is provided on the top of the fish reef body.

[0013] In a second aspect, the present invention further provides a method for optimizing a scour protection structure for an offshore wind turbine foundation, which is used to optimize the scour protection structure for an offshore wind turbine foundation of the first aspect. The optimization method includes optimizing the number and position of openings on the surface of an artificial reef. The steps of optimizing the number and position of openings on the surface of an artificial reef include:

[0014] A three-dimensional numerical flume model containing an artificial reef (2), a pile foundation (a), and a flow field in an ocean wave and current environment is constructed using numerical simulation methods.

[0015] Generate target waves at the inlet boundary of the numerical flume model and complete wave elimination at the outlet boundary of the numerical flume model;

[0016] Solve the NS equations and sediment transport model to obtain the bed shear stress and shear stress gradient around the pile foundation (a);

[0017] Comparison of the effects of different numbers of openings and different opening positions on the shear stress of the seabed around the pile foundation (a);

[0018] Select the optimal number of holes and the best hole layout position when the bed shear stress extreme value is small and evenly distributed.

[0019] In an optional embodiment, the optimization method further includes calculating the bottom plate width b and thickness t2, including the steps of:

[0020] Make the anti-slip coefficient S1 of the artificial reef greater than 1.3 and the anti-overturning coefficient S2 greater than 1.3;

[0021] Among them, the calculation formula of the anti-slip coefficient S1 is:

[0022]

[0023] The calculation formula for the anti-overturning coefficient S2 is:

[0024]

[0025] Where: W is the weight of the artificial reef, which is the sum of the weight of the main body of the reef W1 and the weight of the bottom plate W2, μ is the maximum static friction coefficient between the artificial reef and the bed surface, ρ is the density of seawater, ρ r is the density of the main material of the reef, F is the maximum force of the water flow, l w is the horizontal distance from the center of rotation of the overturned object to the center of gravity, and l w =Rz s tanθ, h0 is the height of the fluid force F, z s is the height of the center of gravity of the artificial reef, θ is the seabed slope angle;

[0026] Where W1=8ρ r gt1(2πR 2 -2nπr 2 ); W2=4ρ r gbt2R;

[0027] Where: b is the width of a single bottom plate, t1 is the thickness of the fish reef body, t2 is the thickness of the bottom plate, R is the radius of the fish reef body, g is the acceleration of gravity, n is the number of openings in the fish reef body, and r is the opening radius.

[0028] In an optional embodiment, before optimizing the number and position of holes on the surface of the artificial reef, the size of the holes needs to be determined.

[0029] The radius r of the opening of the main body of the reef should meet the following requirements: min <r<r max ;

[0030] Where r minThe lower limit of the hole radius is determined by the length of the main economic fish in the sea area where artificial reefs are deployed, and is 0.8 to 1.5L. f , L f is the body length of economic fish; r max The upper limit of the opening radius is determined by the body length of the predator and is 0.3 to 0.5L. p , L p The length of the predator.

[0031] In an optional embodiment, the optimization method further includes: optimizing the layout of the fish reef group through a water tank test, and the steps of optimizing the layout of the fish reef group through the water tank test include:

[0032] Install pile foundation forms in the flume;

[0033] Take out several artificial reef models and arrange them in an array outside the pile foundation model;

[0034] The distance between each artificial reef and the pile foundation was gradually increased, and scour tests were carried out to obtain the relationship between the distance and the scour depth around the pile foundation model, and to determine the layout spacing when the scour depth is minimum. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the specific embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A top view of a scour protection structure for an offshore wind turbine foundation installed at a pile foundation according to an embodiment of the present invention;

[0037] Figure 2 A three-dimensional view of the stopper, sleeve, and pile foundation after installation in an embodiment of the present invention;

[0038] Figure 3 is a three-dimensional view of an artificial reef according to an embodiment of the present invention;

[0039] Figure 4 1. A top view of the main body of an artificial reef in an embodiment of the present invention;

[0040] Figure 5 This is a front view of the artificial reef during hoisting in an embodiment of the present invention;

[0041] Figure 6 Schematic diagram showing the effect of the cross-sectional area on the anti-slip and anti-overturning capabilities of an artificial reef when a bottom plate is added in an embodiment of the present invention;

[0042] Figure 7 A schematic flow chart of the steps for optimizing the number and location of openings on the surface of artificial reefs in a method for optimizing a scour protection structure for an offshore wind turbine foundation provided by an embodiment of the present invention;

[0043] Figure 8 A schematic flow chart of the steps for optimizing the layout of fish reefs through a water tank test in a method for optimizing a scour protection structure for an offshore wind turbine foundation provided in an embodiment of the present invention.

[0044] Description of reference numerals:

[0045] 1. Install the sleeve;

[0046] 2. Artificial reef; 21. Reef body; 211. Centering hole; 212. Drain hole; 213. Lifting hole; 214. Limiting groove; 22. Bottom plate;

[0047] 3. Stopper; 31. Limiting plate; 32. Stop side plate;

[0048] 4. Hook;

[0049] 5. Submarine pipelines;

[0050] a. Pile foundation;

[0051] H. The distance between the outer wall of the installation sleeve and the outer wall of the fish reef body;

[0052] K. Incoming flow direction. DETAILED DESCRIPTION

[0053] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0054] In the description of this application, it should be understood that the terms "center", "up", "down", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0055] In the description of the present application, unless otherwise specified, “plurality” means two or more.

[0056] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0057] The following combination Figures 1 to 8 , describing embodiments of the present invention.

[0058] According to an embodiment of the present invention, on the one hand, the present invention provides a scour protection structure for an offshore wind turbine foundation, comprising a pile foundation a, and an installation sleeve 1 and an artificial reef 2 installed on the pile foundation a.

[0059] like Figure 1 As shown, the scour protection structure for an offshore wind turbine foundation further includes a stopper 3 .

[0060] Among them, Figures 1 to 6 As shown, the mounting sleeve 1 is sleeved and installed on the pile foundation a, the artificial fish reef 2 includes a fish reef body 21, and the inner wall of the fish reef body 21 is enclosed with the seabed surface to form a habitat chamber; the stop member 3 includes a limit plate 31 and a stop side plate 32, one end of the limit plate 31 along its length direction is connected to the outer wall of the mounting sleeve 1, and the other end of the limit plate 31 along its length direction passes through the fish reef body 21 and extends into the habitat chamber, the stop side plate 32 is installed at the other end of the limit plate 31 along its length direction, and the stop side plate 32 is used to abut the inner wall of the fish reef body 21.

[0061] In this manner, the stopper 3 is provided to limit the movement of the reef body 21 in the direction away from the pile foundation a.

[0062] Specifically, by setting a stopper 3 including a limit plate 31 and a stop side plate 32, and extending the stop side plate 32 into the habitat chamber of the fish reef body 21 and abutting against its inner wall, a reliable limit is formed, which can directly limit the horizontal freedom of the artificial fish reef 2 relative to the installation sleeve 1 and the pile foundation a, and prevent the fish reef body 21 from failing and displacing relative to the pile foundation a.

[0063] The scour protection structure provided by the present invention can form a reliable technical solution for the integrated development of offshore wind farms and marine ranches. Compared with traditional artificial reefs 2, it can avoid displacement and dislocation problems under the action of long-term hydrodynamic loads such as waves and currents, and prevent the loss of artificial reefs 2.

[0064] At the same time, it can fix the artificial reef 2 and ensure that the artificial reef 2 is always located at the designed position, so that its flow disturbance and energy dissipation functions can be stably exerted, and the high-speed water flow around the wind turbine pile foundation can be more effectively weakened, reducing or even preventing the occurrence of local scouring of the seabed, and providing more reliable scouring protection for the wind turbine foundation.

[0065] In addition, ensure that the artificial reef 2 is arranged in the designated sea area in a long-term and stable manner, providing a stable and reliable shelter, breeding and feeding place for marine organisms such as fish and shellfish, and improving the effectiveness and sustainability of marine ranch ecological restoration and fishery enhancement.

[0066] It can be explained that, if Figure 3 and Figure 5 As shown, the fish reef body 21 is provided with a limiting groove 214 . When installed, the limiting groove 214 is buckled to the limiting plate 31 .

[0067] Furthermore, the number of the limiting grooves 214 is consistent with the number of the limiting plates 31 .

[0068] It can be explained that the installation sleeve 1 is made of concrete and steel bars during production and is placed on the seabed surface by hoisting.

[0069] Furthermore, the length of the limiting plate 31 is equal to the sum of the distance between the outer wall of the fish reef body 21 and the outer wall of the installation sleeve 1 plus the thickness of the fish reef body 21 .

[0070] In one embodiment, Figures 3 to 5 As shown, the fish reef body 21 is further provided with a centering hole 211 for adjusting the center of gravity of the fish reef body 21 and providing a passage for fish.

[0071] It can be explained that there are multiple centering holes 211 .

[0072] Preferably, if Figures 3 to 5 As shown, there are multiple rows of centering hole groups, which are spaced apart along the central axis of the annular contact end face. Each row of centering hole groups is provided with multiple centering holes 211 arranged in a circular array around the central axis of the annular contact end face.

[0073] In this way, by arranging multiple rows of centering holes 211 at intervals along the central axis of the annular contact end face, the center of gravity of the fish reef body 21 can be flexibly adjusted toward the center of the structure. By arranging the multiple centering holes 211 in each row of centering hole groups in a circular array around the central axis of the annular contact end face, local mass concentration can be eliminated, ensuring that the center of gravity of the fish reef body 21 is always on the central axis during the lifting process, avoiding tilting, flipping, etc. during lifting.

[0074] Further, if Figures 3 to 5 As shown, the centering holes 211 of two adjacent rows of centering hole groups are staggered in the circumferential direction.

[0075] With such a setting, by staggering the centering holes 211 of two adjacent rows of centering hole groups by a certain angle in the circumferential direction, the lateral shear resistance can be improved, and the occurrence of local uneven force and structural instability when the traditional centering hole group installation alignment method is avoided (that is, the centers of the corresponding two centering holes 211 in two adjacent rows of centering hole groups are on the same busbar).

[0076] It should be noted that the centering hole 211 close to the drain hole 212 in the height direction can also be used as a hoisting hole 213 during installation and disassembly.

[0077] Furthermore, lifting ropes are installed at at least two centering holes 211 used as lifting holes 213, and the lifting ropes are tied and fixed. During lifting, the lifting ropes are hooked using the hook 4.

[0078] Among them, the lifting hole 213 is chamfered.

[0079] In one embodiment, Figure 1 、 Figures 3 to 5 As shown, the fish reef body 21 is a hemispherical shell, the annular contact end surface of the hemispherical shell is in contact with the seabed surface, and the arc-shaped wall of the hemispherical shell is in contact with the seawater; the artificial fish reef 2 also includes a bottom plate 22, which is installed on the annular contact end surface.

[0080] It can be explained that the fish reef body 21 and the bottom plate 22 are made by integral casting.

[0081] Further, if Figure 3 As shown, there are two bottom plates 22 arranged in a cross shape to adjust the height of the center of gravity of the structure.

[0082] In this way, by adding the bottom plate 22 and the installation sleeve 1, the anti-slip, anti-overturning and anti-sinking capabilities of the artificial reef 2 can be improved, providing long-term scour protection for the artificial reef 2 itself.

[0083] It can be explained that there are multiple artificial reefs 2.

[0084] Furthermore, there is no specific limitation on the arrangement of the plurality of artificial reefs 2 .

[0085] As one of the implementation methods, Figure 1 As shown, a plurality of artificial reefs 2 are arranged in a circular array around the central axis of the installation sleeve 1 .

[0086] Such an arrangement will form a diversion structure on the artificial reef 2 on the upstream side, diverting the water flowing into the gaps between the reef bodies, reducing the water flow velocity, and thus reducing the impact of the water flow on the seabed around the pile foundation a.

[0087] Of course, in other optional embodiments, several artificial fish reef 2 models are arranged in a square to form a fish reef group.

[0088] In this way, by aligning one of the edges of the square layout formed by the fish reef group perpendicular to the direction of water flow, the artificial fish reef 2 around the pile foundation a can consume the energy of the incoming flow by forming turbulence, effectively reducing the flow field intensity around the pile foundation a, thereby weakening the scouring effect.

[0089] Among them, when arranging the artificial reefs 2, arranging more artificial reefs 2 in the streamline direction (parallel to the incoming flow direction K) can further reduce the scouring effect on the area around the pile foundation a.

[0090] In addition, a turbulent environment can be formed around the pile foundation a, and under the guidance of the outer wall of the fish reef body 21, nutrients are guided to the surrounding of the pile foundation a, providing conditions for fish to gather and multiply.

[0091] That is, the artificial reef 2 is in contact with the outer wall of the pile foundation a. Under this arrangement, the maximum scour depth is reduced by 53%.

[0092] With such arrangement, several artificial reefs 2 can work together.

[0093] In one embodiment, Figure 3 and Figure 4 As shown, a drain hole 212 is provided on the top of the fish reef body 21 .

[0094] In this configuration, by providing an exhaust hole 212 at the top of the fish reef body 21, the gas inside the fish reef body 21 is easily discharged, thereby avoiding residual air cavity after the fish reef body 21 is installed.

[0095] It can be explained that in order to improve the ecological environment of the artificial reef 2 , bionic grass is laid above the bottom plate 22 .

[0096] Such an arrangement is beneficial to the attachment of organisms and sedimentation inside the fish reef body 21.

[0097] like Figure 1 As shown, during installation, several artificial reefs 2 are hoisted outside the pile foundation a by a hoisting vessel, and installation space is reserved for the submarine pipeline 5.

[0098] The artificial reef 2 manufactured using the above-mentioned optimization method for the scour protection structure of the offshore wind turbine foundation has a relatively simple manufacturing process and installation process, which is conducive to reducing costs.

[0099] In a second aspect, the present invention further provides a method for optimizing a scour protection structure for an offshore wind turbine foundation, which is used to optimize the scour protection structure for an offshore wind turbine foundation of the first aspect.

[0100] like Figure 7As shown, the optimization method includes optimizing the number and position of the holes on the surface of the artificial reef 2. The steps of optimizing the number and position of the holes on the surface of the artificial reef 2 include:

[0101] A three-dimensional numerical flume model containing artificial reef 2, pile foundation a and flow field in an ocean wave and current environment was constructed using numerical simulation methods.

[0102] Generate target waves at the inlet boundary of the numerical flume model and complete wave elimination at the outlet boundary of the numerical flume model;

[0103] The NS equations and sediment transport model are solved to obtain the bed shear stress and shear stress gradient around pile foundation a.

[0104] Compare the effects of different opening numbers and opening positions on the shear stress of the seabed around pile foundation a;

[0105] Select the optimal number of holes and the best hole layout position when the extreme (minimum) shear stress of the bed surface is small and evenly distributed.

[0106] With this setting, by optimizing the number and location of openings on the surface of the artificial reef 2, the stress points of water flow and load are reasonably distributed. Based on the results of numerical simulation, the optimal number of openings and the best hole layout are selected to effectively disperse the impact of waves and currents on the structure, and guide the water flow to pass through or bypass the reef structure more smoothly, thereby reducing the overturning moment.

[0107] At the same time, by adopting numerical simulation methods, the optimization process is no longer an empirical trial and error, but can accurately quantify the impact of different opening schemes (different numbers, different positions) on key stability indicators (seabed shear stress, flow field distribution, and scour morphology), and efficiently identify the optimal opening configuration, which can reduce test costs and shorten the test cycle.

[0108] In addition, by constructing a complete model including artificial reef 2, pile foundation a and flow field, the coupling effect of waves and water flow in the actual marine environment can be simulated. By generating waves that meet the characteristics of the target sea area (such as wave height and period) at the inlet boundary, the simulated environment is ensured to be close to the real scene. Then, wave elimination is completed at the outflow boundary to reduce the interference of wave reflection on the results. The measured shear stress distribution of the seabed around pile foundation a can truly reflect the sediment transport direction and erosion rate, providing data support for the subsequent optimization of the number and location of openings.

[0109] Among them, the details of fluid movement, such as velocity field, pressure field and sediment flux, should be considered during the modeling process.

[0110] In one embodiment, the optimization method further includes calculating the width b and thickness t2 of the bottom plate 22, including the steps of:

[0111] Make the anti-slip coefficient S1 of the artificial reef 2 greater than 1.3 and the anti-overturning coefficient S2 greater than 1.3;

[0112] Among them, the calculation formula of the anti-slip coefficient S1 is:

[0113]

[0114] The calculation formula for the anti-overturning coefficient S2 is:

[0115]

[0116] Where: W is the weight of the artificial reef 2, which is the sum of the weight of the reef body 21 W1 and the weight of the bottom plate 22 W2, μ is the maximum static friction coefficient between the artificial reef 2 and the bed surface, ρ is the density of seawater, ρr is the material density of the reef body 21, F is the maximum force of the water flow, l w is the horizontal distance from the center of rotation of the overturned object to the center of gravity, and l w =Rz s tanθ, h0 is the height of the fluid force F, z s is the height of the center of gravity of artificial reef 2, θ is the seabed slope angle;

[0117] Where W1=8ρ r gt1(2πR 2 -2nπr 2 ); W2=4ρ r gbt2R;

[0118] Where: b is the width of a single bottom plate 22, t1 is the thickness of the fish reef body 21, t2 is the thickness of the bottom plate 22, R is the radius of the fish reef body 21, g is the acceleration of gravity, n is the number of openings in the fish reef body 21, and r is the opening radius.

[0119] With this setting, by using mathematical formulas to quantitatively evaluate the structural stability, it is clearly required that the anti-slip coefficient and anti-overturning coefficient meet the requirements, ensuring that the design meets the safety threshold, and the anti-slip and anti-overturning capabilities can be scientifically verified.

[0120] At the same time, the width b and thickness t2 of the bottom plate 22 are associated with the geometric parameters of the artificial reef 2 (such as the radius R and the number of openings n) to achieve parameter coordination. That is, the optimal width and thickness of the bottom plate 22 that can ensure safety and avoid waste are accurately calculated, thereby improving the economy of the overall structure.

[0121] It can be explained that the base plate 22 can be made of reinforced concrete.

[0122] Of course, in other optional implementations, the bottom plate 22 may also be made of other high-density materials, such as steel, to serve as an auxiliary counterweight.

[0123] It can be explained that when calculating the width b and thickness t2, the radius 3m, thickness 0.1m, and density 2300kg / m 3 The artificial reef 2 is applied to the scour protection of the single pile foundation a, and the specific wave and current conditions are simulated to complete the calculation. The results show that the addition of the bottom plate 22 can effectively enhance the anti-slip stability and anti-overturning stability of the artificial reef 2, and based on Figure 4 When the design requirements of S1>1.3 and S2>1.3 are met, the minimum cross-sectional area of ​​the bottom plate 22 is 0.13m 2 .

[0124] In one embodiment, before optimizing the number and positions of the holes on the surface of the artificial reef 2 , the size of the holes needs to be determined.

[0125] Specifically, the opening radius r of the reef body 21 should satisfy: min <r<r max ;

[0126] Where r min The lower limit of the opening radius is determined by the body length of the main economic fish in the sea area where artificial reef 2 is deployed, and is 0.8~1.5L f , L f is the body length of economic fish; r max The upper limit of the opening radius is determined by the body length of the predator and is 0.3 to 0.5L. p , L p The length of the predator.

[0127] This setting, by quantifying the body length relationship between economic fish and predators, adjusts the aperture range so that the aperture can meet the feeding and reproduction needs of economic fish, and can also reduce the interference of predators, build a safety barrier, and prevent predators from entering the reef.

[0128] At the same time, it can also provide a base for shellfish and algae to attach to.

[0129] Among them, it was found in actual application that the water flow weakening effect was better when the opening radius of the artificial reef 2 was 0.1 times the diameter of the artificial reef 2 and the number of openings was 5. At this time, the maximum shear stress and shear stress gradient of the bed surface around pile foundation a decreased by 30% and 54% respectively compared with the condition without artificial reef 2.

[0130] It can be explained that the OPENFOAM open source program was used to build a three-dimensional numerical flume model including artificial reef 2, pile foundation a and flow field by taking advantage of its flexibility and good solving ability.

[0131] It can be explained that the OlaFlow solver is used to generate waves.

[0132] Specifically, based on the VOF method, waves and water currents are generated in combination with push plate wave generation or velocity inlet wave generation technology.

[0133] Among them, push-plate wave generation is to generate complex waves by pushing the fluid through a moving boundary (such as a virtual push-plate).

[0134] Velocity inlet wave generation is to directly apply a velocity field to drive the fluid to generate regular waves, such as Stokes waves.

[0135] Furthermore, when generating waves, parameters such as wave height, wavelength, and period are input to ensure that the generated waves meet the requirements of physical experiments or actual engineering projects.

[0136] It can be explained that the active wave absorption method is used to eliminate waves and avoid wave reflection at the boundary, thereby avoiding the reflected wave from affecting the simulation results and causing flow field distortion when it propagates in the opposite direction and superimposes on the incident wave.

[0137] This setting can more efficiently eliminate secondary reflections, shorten the water tank length, and reduce computing costs.

[0138] In one embodiment, Figure 8 As shown, the optimization method further includes: optimizing the layout of the fish reef group through a water tank test. The steps of optimizing the layout of the fish reef group through the water tank test include:

[0139] Install pile foundation a model in the water tank;

[0140] Take out several artificial reef 2 models and arrange them in an array outside the pile foundation a model;

[0141] The distance between each artificial reef 2 and the pile foundation a was gradually increased, and scour tests were carried out to obtain the relationship between the distance and the scour depth around the pile foundation a model, and to determine the layout spacing when the scour depth was minimum.

[0142] In this setting, by installing the pile foundation a model in the water tank and taking out several fish reef 2 models to array outside the pile foundation a model, by adjusting the spacing and recording the scour depth around the pile foundation a under different spacing conditions, a relationship curve between spacing and scour depth is established to screen out the optimal layout.

[0143] It can be explained that the spacing determined by the definition experiment is the optimal spacing H.

[0144] Preferably, the optimal spacing H of the artificial reefs 2 around the pile foundation a is 0 times the pile diameter, at which point the maximum scouring depth is reduced by 53%.

[0145] Among them, when H is 0.5 times the pile diameter, the maximum scour depth under this arrangement decreases by 25%.

[0146] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A scour protection structure for an offshore wind turbine foundation, characterized in that: include: An installation sleeve (1) is sleeved and installed on the pile foundation (a); An artificial fish reef (2) comprises a fish reef body (21), wherein the inner wall of the fish reef body (21) and the seabed are combined to form a habitat chamber; The stopper (3) comprises a limit plate (31) and a stop side plate (32), wherein one end of the limit plate (31) along its length direction is connected to the outer wall of the mounting sleeve (1), and the other end of the limit plate (31) along its length direction passes through the fish reef body (21) and extends into the habitat chamber, and the stop side plate (32) is mounted on the other end of the limit plate (31) along its length direction, and the stop side plate (32) is used to abut against the inner wall of the fish reef body (21).

2. The scour protection structure for offshore wind turbine foundation according to claim 1, characterized in that: The fish reef body (21) is provided with multiple rows of centering hole groups, which are arranged at intervals along the central axis direction of the annular contact end face, and each row of the centering hole groups is provided with multiple centering holes (211) arranged in a circumferential array around the central axis of the annular contact end face.

3. The scour protection structure for offshore wind turbine foundation according to claim 2, characterized in that: The centering holes (211) of two adjacent rows of the centering hole groups are arranged in a circumferentially staggered manner.

4. The scour protection structure for an offshore wind turbine foundation according to any one of claims 1 to 3, characterized in that: The fish reef body (21) is in the form of a hemispherical shell, the annular contact end surface of the hemispherical shell contacts the seabed surface, and the arc-shaped wall of the hemispherical shell contacts the seawater; The artificial fish reef (2) further comprises a bottom plate (22), and the bottom plate (22) is mounted on the annular contact end surface.

5. The scour protection structure for an offshore wind turbine foundation according to any one of claims 1 to 3, characterized in that: A plurality of the artificial fish reefs (2) are provided, and the plurality of the artificial fish reefs (2) are arranged in a circular array around the central axis of the installation sleeve (1).

6. The scour protection structure for an offshore wind turbine foundation according to any one of claims 1 to 3, characterized in that: The top of the fish reef body (21) is provided with an emptying hole (212).

7. A method for optimizing a scour protection structure for an offshore wind turbine foundation, for optimizing the scour protection structure for an offshore wind turbine foundation according to any one of claims 1 to 6, characterized in that: The optimization method includes optimizing the number and position of openings on the surface of the artificial reef (2). The steps of optimizing the number and position of openings on the surface of the artificial reef (2) include: A three-dimensional numerical flume model containing an artificial reef (2), a pile foundation (a), and a flow field in an ocean wave and current environment is constructed using numerical simulation methods. Generate target waves at the inlet boundary of the numerical flume model and complete wave elimination at the outlet boundary of the numerical flume model; Solve the NS equations and sediment transport model to obtain the bed shear stress and shear stress gradient around the pile foundation (a); Comparison of the effects of different numbers of openings and different opening positions on the shear stress of the seabed around the pile foundation (a); Select the optimal number of holes and the best hole layout position when the bed shear stress extreme value is small and evenly distributed.

8. The optimization method for the scour protection structure of an offshore wind turbine foundation according to claim 7, characterized in that: The optimization method further comprises calculating the width b and thickness t2 of the bottom plate (22), comprising the steps of: Make the anti-slip coefficient S1 of the artificial reef (2) greater than 1.3 and the anti-overturning coefficient S2 greater than 1.3; Among them, the calculation formula of the anti-slip coefficient S1 is: The calculation formula for the anti-overturning coefficient S2 is: Where: W is the weight of the artificial reef (2), which is the sum of the weight of the reef body (21) W1 and the weight of the bottom plate (22) W2, μ is the maximum static friction coefficient between the artificial reef (2) and the bed surface, ρ is the density of seawater, ρ r is the material density of the main body of the reef (21), F is the maximum force of the water flow, l w is the horizontal distance from the center of rotation of the overturned object to the center of gravity, and l w =Rz s tanθ, h0 is the height of the fluid force F, z s is the height of the center of gravity of the artificial reef (2), θ is the seabed slope angle; Where W1=8ρ r gt1(2πR 2 -2nπr 2 ); W2=4ρ r gbt2R; Where: b is the width of a single bottom plate (22), t1 is the thickness of the fish reef body (21), t2 is the thickness of the bottom plate (22), R is the radius of the fish reef body (21), g is the acceleration of gravity, n is the number of openings in the fish reef body (21), and r is the opening radius.

9. The optimization method for the scour protection structure of an offshore wind turbine foundation according to claim 8, characterized in that: Before optimizing the number and location of holes on the surface of the artificial reef (2), the size of the holes must be determined. The opening radius r of the fish reef body (21) should satisfy: min <r<r max ; Where r min The lower limit of the opening radius is determined by the length of the main economic fish in the sea area where the artificial reef (2) is placed, and is 0.8~1.5L f , L f is the body length of economic fish; r max The upper limit of the opening radius is determined by the body length of the predator and is 0.3 to 0.5L. p , L p The length of the predator.

10. The method for optimizing a scour protection structure for an offshore wind turbine foundation according to any one of claims 7 to 9, characterized in that: The optimization method also includes: optimizing the layout of fish reefs through tank testing. The steps of optimizing the layout of fish reefs through tank testing include: Installation of pile foundation in water tank (a) Model; Take out several artificial reef (2) models and arrange them in an array outside the pile foundation (a) model; The distance between each artificial reef (2) and the pile foundation (a) is gradually increased, and scour tests are carried out to obtain the relationship between the distance and the scour depth around the pile foundation (a) model, and to determine the layout distance when the scour depth is the smallest.

Images