A bottom-protecting artificial fish reef for offshore wind farms

Abstract

The present invention discloses a bottom-protecting artificial fish reef for offshore wind farms, which belongs to the field of new energy and agricultural innovation integration technology. It includes multiple reef bodies, each of which is composed of an annular horizontal plate, a conical side plate, a cylindrical side plate, a cross-section support plate and a cubic foot. It is easy to deploy, has good anti-slip and anti-overturning properties, and the overall plate structure is made of basalt composite bars and reinforced concrete, which greatly improves the service life of the reef body and the area of ​​biological attachment. The special conical side plate plays a role in protecting the seabed from scouring. Its streamlined structure allows a smooth transition of the water depth between the seabed and the wind turbine foundation, effectively protecting the high flow velocity area caused by the wind turbine foundation from the scouring area of ​​the bottom. After the seabed is easily scoured, the scouring of sediment is close to the natural sea area, which can effectively reduce the scouring around the foundation. The circular hole inside the reef body can increase the turbulence intensity inside the reef body, which is suitable for swimming animals to hide and live.

Description

Technical Field

[0001] The present invention relates to the field of new energy and agricultural innovation integration technology, and in particular to an artificial fish reef used to integrate offshore wind farms with marine ranches to achieve wind power pile foundation anti-scour and biological conservation and proliferation benefits. Background Art

[0002] The integration of marine ranching and offshore wind power is still in its infancy in China, and relevant research is still underway. Due to the relative lack of traditional energy sources in Europe, offshore wind power development has been relatively early. Research literature has found that fish such as cod and mackerel gather under the foundations of some French wind turbines. Offshore wind turbine foundations themselves serve as a good biomass, and after the wind farm is operational, they actually function, to a certain extent, as artificial reefs for fish proliferation and aggregation. The foundations of offshore wind farms redistribute the flow patterns of the surrounding seawater, creating upwelling zones and slower-flowing back eddies. This enhances vertical mixing of the water, particularly by promoting the transport of high-nutrient-rich deep water to the surface, significantly increasing the concentrations of nutrients such as nitrates and phosphates in the euphotic zone. This promotes the growth of various phytoplankton and zooplankton, boosting primary and secondary productivity in the ocean. Furthermore, the biofilm attached to the turbine foundations attracts fish and other swimming organisms to feed and inhabit, forming a highly complex food chain.

[0003] However, offshore wind farm foundations in high sea conditions, while supporting power generation, are often accompanied by scouring around the turbine foundations. In severe cases, this can compromise the foundation's stability and safety. Under the combined effects of wind, waves, and currents, the surrounding seafloor sediments undergo erosion, hollowing, and liquefaction. This reduces the turbine foundation's burial depth, the pile insertion depth, and the bearing capacity of the wind turbine foundation. This increases the pile's cantilever length and reduces the pile's natural frequency, ultimately compromising the turbine's safety. Traditional bottom protection methods involve riprap, but this lacks integrity and is ineffective. Therefore, in the context of integrating new energy and agriculture, the call for comprehensive and rational use of the sea is being made. Selecting organisms suitable for the natural conditions of the sea and designing components that integrate offshore wind farms with marine ranches are key points and challenges in current research on "integrated wind and ranching" in the ocean. Designing artificial reefs that effectively reduce the scouring depth of wind turbine foundations, are stable, economical, durable, and suitable for the habitat and growth of target species, is a core component of this research. By focusing on the concept of integration, we can achieve the economic benefits of increasing species (fish, shellfish, etc.), and realize the dynamic complementarity between energy and fisheries on the basis of maintaining wind turbine foundations and protecting biological resources. Summary of the Invention

[0004] The present invention aims to solve the technical problems mentioned in the above background technology by adopting the following technical solutions:

[0005] A bottom-protecting and proliferation-type artificial fish reef for offshore wind farms comprises a plurality of reef bodies, each of the reef bodies being composed of an annular horizontal plate, a conical side plate, a cylindrical side plate, a cross-sectional support plate and a cubic foot seat. The number of the annular horizontal plates is two, which are divided into a top plate and a bottom plate. One side of the top plate is connected to the top of the cylindrical side plate, and the other side is connected to the top of the conical side plate. One side of the bottom plate is connected to the bottom of the cylindrical side plate, and the other side is connected to the bottom of the conical side plate. The angle between the cylindrical side plate and the horizontal plane is a right angle, and the angle between the conical side plate and the horizontal plane is an acute angle. The top plate, bottom plate, conical side plate and cylindrical side plate are commonly connected to a cross-sectional support plate; and a cubic foot seat is respectively installed at the four corners of the bottom of each of the bottom plates.

[0006] As a preferred example, the number of the conical side panels is one, the number of the cylindrical side panels is one, the number of the cubic foot seats is four, and the number of the cross-sectional support plates is exactly one.

[0007] As a preferred example, the curvature of each of the annular horizontal plates is π / 4, the conical side plates are composed of one eighth of a conical surface, and the curvature of the cylindrical side plates is π / 4.

[0008] As a preferred example, each of the bottom plate and cross-section support plate is provided with a plurality of circular holes of the same size and shape. The cross-section support plate is located on the axis of symmetry of the main body, dividing the interior of the reef into two chambers of equal size.

[0009] As a preferred example, the shape of each reef body is truncated cone.

[0010] As a preferred example, each of the reef bodies is cast by basalt composite bars and reinforced concrete, and the reef bodies are combined in pairs to form a ring, surrounding the wind turbine foundation.

[0011] It should be noted that the number of the wind turbine foundations is N×M, where N represents the number of rows and N≥2, and M represents the number of columns and M≥2. The wind turbine foundations in each column are electrically connected via cables (M=N or M≠N).

[0012] The beneficial effects of the present invention are as follows: the present invention provides a reef body composed of an annular horizontal plate, a conical side plate, a cylindrical side plate, a cross-section support plate and a cubic foot seat, which is easy to deploy and has good anti-slip and anti-overturning properties. The overall plate structure is made of basalt composite reinforcement and reinforced concrete, which greatly improves the service life of the reef body and also increases the surface area of ​​the reef body, which is conducive to the attachment of organisms such as shellfish. The special conical side plate plays a protective role in preventing scouring of the seabed substrate. Its streamlined structure allows a smooth transition of the water depth between the seabed and the wind turbine foundation, so that the high flow velocity area caused by the wind turbine foundation obstruction can be effectively protected from the scouring area of ​​the substrate. After the scouring position of the seabed is expanded outward, the kinetic energy of the fluid is close to that of the natural sea area, and the scouring of sediment is also close to that of the natural sea area.

[0013] The upwelling generated in front of the reef accelerates the vertical mixing of the water body, bringing most of the nutrients in the bottom layer of the front of the reef to the surface of the water body, increasing the primary and secondary productivity of marine plankton, benthic organisms, etc., thereby increasing the output of economic organisms such as marine swimming animals. The circular holes opened inside increase the permeability and turbulence intensity inside the reef body, which is conducive to the hiding of organisms. The top plate blocks part of the downwelling, destroying the formation of the "horseshoe vortex", reducing the turbulent kinetic energy of the disturbed water body, and narrowing the range of sediment being swept up, thereby reducing local scouring of the wind turbine foundation. The back vortex at the rear creates an environment suitable for swimming animals to spawn and reproduce, and increase the number of target species of fish and shellfish in the project area.

[0014] The present invention greatly increases the water permeability and air permeability of the reef body by providing multiple circular holes in the bottom plate and the cross-section support plate. On the one hand, it reduces the material cost while ensuring the overall rigidity and strength. On the other hand, it can provide a living environment for different organisms to live and avoid enemies.

[0015] This invention aims to design a large-area anti-settling structure at the bottom while strictly controlling the overall weight of the reef, ensuring that it does not sink or sag, thereby preventing siltation at the bottom of the wind turbine foundation. Four cubic footings at the bottom protect against strong currents in the project area, thereby ensuring the reef's resistance to overturning, sliding, and flipping, and enhancing its stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0017] Figure 2 It is the front view of the present invention;

[0018] Figure 3 It is a left side view of the present invention;

[0019] Figure 4 It is a right side view of the present invention;

[0020] Figure 5Schematic diagram of the cross-section support plate structure of the present invention

[0021] Figure 6 Schematic diagram of the bottom plate structure of the present invention;

[0022] Figure 7 This is a schematic diagram of the single pile placement of the present invention;

[0023] Figure 8 A schematic diagram of terrain changes in the numerical simulation of sediment erosion and deposition according to the present invention;

[0024] Figure 9 Curve of the impact depth variation over time for the numerical simulation of the fan foundation;

[0025] Figure 10 This is the curve of the change of the impact depth of the numerical simulation section of the present invention and the fan foundation over time;

[0026] Figure 11 This is a comparison curve of the change of sediment volume over time with and without reefs.

[0027] In the figure, 1. annular horizontal plate, 11. top plate, 12. bottom plate, 2. conical side plate, 3. cylindrical side plate, 4. section support plate, 5. cube foot, 6. circular hole, 7. fan foundation, 8. cable. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific illustrations and embodiments.

[0029] like Figure 1-11 As shown, an artificial fish reef of the bottom protection and proliferation type for offshore wind farms includes multiple reef bodies, each reef body consists of an annular horizontal plate 1, a conical side plate 2, a cylindrical side plate 3, a cross-sectional support plate 4 and a cubic foot 5. There are two annular horizontal plates 1, which are divided into a top plate 11 and a bottom plate 12. One side of the top plate 11 is connected to the top of the cylindrical side plate 3, and the other side is connected to the top of the conical side plate 2. One side of the bottom plate 12 is connected to the bottom of the cylindrical side plate 3, and the other side is connected to the bottom of the conical side plate 2. The angle between the cylindrical side plate 3 and the horizontal plane is a right angle, and the angle between the conical side plate 2 and the horizontal plane is an acute angle. The top plate 11, the bottom plate 12, the conical side plate 2 and the cylindrical side plate 3 are commonly connected to the cross-sectional support plate 4; and the four corners of the bottom of each bottom plate 12 are respectively installed with a cubic foot 5.

[0030] There is one conical side panel 2 , one cylindrical side panel 3 , four cubic foot plates 5 , and only one cross-sectional support plate 4 .

[0031] The radian of each annular horizontal plate 1 is π / 4, the conical side plate 2 is composed of one eighth of a conical surface, and the radian of the cylindrical side plate 3 is π / 4.

[0032] The width of each base plate is preferably 2 / 3 of the width between the fan foundations. Each base plate 12 and cross-section support plate 4 is provided with a plurality of circular holes 6 of the same size and shape.

[0033] The shape of each reef is truncated cone.

[0034] Each reef body is made of basalt composite reinforcement and reinforced concrete, and the reef bodies are combined into a ring shape in pairs, surrounding the wind turbine foundation 7.

[0035] The number of wind turbine foundations 7 is N×M, where N represents the number of rows and N≥2, and M represents the number of columns and M≥2. The wind turbine foundations 7 in each column are connected by a cable 8 (M=N or M≠N).

[0036] like Figure 1 As shown, the shape of each reef is a truncated cone with a height of 1 / 3 of the bottom plate width. The conical side plate 2 arranged on the upstream side relieves the strong flow velocity around the fan foundation 7, weakens the streamline compression zone of the side wall of the fan foundation 7, and disperses the corresponding area with high flow velocity. As a result, the low-pressure area around the fan foundation 7 increases in scope and decreases in intensity, the pressure difference around the fan foundation 7 decreases, and the sand-carrying capacity of the water flow decreases; on the other hand, the area for biological attachment is increased, and the primary productivity and secondary productivity are improved; the water flow on the downstream side of the fan foundation 7 tends to be flat under the obstruction of the reef body, and the low-velocity bottom water cannot reach the critical flow velocity for sediment initiation, and the scouring intensity and range around the fan foundation 7 are weakened.

[0037] like Figure 2-5 As shown, the cross-section is hollow, and a cross-section support plate 4 is installed in the middle. The cross-section support plate is provided with circular holes 6 of the same size and shape, with a hole diameter of 0.2m-0.4m. On the one hand, the hollow space of the reef body is increased, which plays a role in dredging and diverting, and is conducive to the movement and hiding of swimming animals. On the other hand, the dead weight of the reef body is reduced, the anti-burial and anti-subsidence capabilities are improved, and the strength, stability and service life of the reef body are also improved.

[0038] Figure 6 The bottom plate 12 of the reef body is provided with circular holes 6 of the same size and shape, with a hole diameter of 0.2m-0.4m. The design of the opening is conducive to increasing the air permeability and water permeability of the reef body, reducing the deadweight of the reef body and the risk of burial.

[0039] like Figure 7This is one of the layout schemes of the present invention. The specific layout scheme can be determined by the sea conditions of the engineering sea area. The wind turbine foundation 7 in the sea area roughly conforms to the characteristics of cylindrical flow. According to the position of the cable 8 of the pile, strong tidal currents and other characteristics, the high flow velocity area on both sides of the main exhaust bottom wind turbine foundation 7 can be used to expand the scouring range and reduce the scouring intensity. On the premise of ensuring the safety of the cable 8 routing, the advantages of anti-scouring and solid foundation are achieved; based on the safety of the submarine routing, 2-3 reefs can be placed on both sides of the rising and falling tides, that is, 4-6 reef units for each single pile.

[0040] In order to further ensure the stability of the invention in engineering sea areas, a numerical experiment on silt scouring and deposition of a typical wind turbine foundation is designed. The specific experimental steps are as follows:

[0041] Using FLOW-3D software, the outer diameter of the pile foundation is 10m, the water depth is 20m, the given incoming flow velocity is 1.1m / s, the turbulence model is selected as large eddy simulation, the sand particle size is 0.11mm, the Manning roughness of the wind turbine foundation 7 and the artificial fish reef is 0.0007m, the critical Shields number is calculated to be 0.0721, the thickness of the sand bed is 10m, the wind turbine foundation 7 and the artificial fish reef are placed in the center of the sand bed, and in order to make the upstream incoming flow and downstream wake fully developed and the water flow smooth, a 10m long fixed bed transition zone is set in the upstream and downstream riverbeds respectively, as shown in the figure. Figure 8 As shown in the figure, at t=30min, due to the compression of streamlines on both sides of the wind turbine foundation 7, there is a high shear force area, so the scouring is most intense, with a maximum scouring depth of 2.4m, and siltation on the upstream and downstream sides; the overall performance is that the siltation intensity is greater than the scouring intensity; after the reef is added, the scouring area expands significantly, the scouring range becomes larger, but the scouring intensity around the wind turbine foundation 7 decreases, the maximum scouring area occurs on the upstream side of the foundation, siltation occurs on the upstream side of the foundation, and the siltation range is significantly increased.

[0042] like Figure 9 It can be seen that in the initial stage, which occurs approximately within the first 15 minutes, scour develops rapidly and the scour depth increases rapidly, reaching 1 / 2-2 / 3 of the final scour depth. During this stage, the size and number of vortices around the wind turbine foundation are small, but the scouring capacity is the strongest. As the scour pit deepens, the water flow velocity at its bottom decreases, and the scouring capacity weakens.

[0043] Then it enters the second stage, the development stage, during which the depth of the scour pit continues to increase, but the rate of increase (Δh / Δt) slows down. The scour process shows a trend close to stability, and the influence of the vertical vortex above the scour pit gradually weakens.

[0044] In the final stage, the scour depth no longer changes significantly over time. A state of equilibrium is reached, with the scour depth asymptotically approaching its maximum value. In this stage, scour is primarily caused by pulsating flow and develops very slowly. The shape of the scour pit remains largely unchanged, and scour gradually stabilizes. At this point, the overall scour topography remains unchanged, and local scour equilibrium is eventually reached.

[0045] like Figure 10-11 As shown in the figure, after the fish reefs were deployed, the scouring in front of the wind turbine foundation gradually stabilized from rapid development, the time to reach scouring equilibrium around the wind turbine foundation was greatly shortened, the scouring depth gradually decreased, the rate of change of the scouring volume with time decreased, and the scouring range did not change significantly; there was obvious scouring at the leading and trailing edges of the reef, which was caused by the downflow generated by the headwind surface and the turbulent area with slower flow behind the fish reef.

[0046] It should be noted that the present invention can be based on a four-reef combination or a six-reef combination. After the piling is completed, the reef can be placed simultaneously. Without hindering the laying of the cable 8, the positioning system can be combined to accurately place the reef body.

[0047] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. Various changes and improvements can be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements are within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An artificial reef with a bottom protection and proliferation type for an offshore wind farm, comprising a plurality of reef bodies, characterized in that: The reef bodies are combined in pairs to form a ring, surrounding the wind turbine foundation (7). Each reef body is composed of a ring-shaped horizontal plate (1), a conical side plate (2), a cylindrical side plate (3), a cross-sectional support plate (4) and a cubic foot seat (5). There are two ring-shaped horizontal plates (1), which are divided into a top plate (11) and a bottom plate (12). One side of the top plate (11) is connected to the top of the cylindrical side plate (3), and the other side is connected to the top of the conical side plate (2). The conical side plate (2) It is composed of one eighth of a conical surface, one side of the bottom plate (12) is connected to the bottom of the cylindrical side plate (3), and the other side is connected to the bottom of the conical side plate (2), and the angle between the cylindrical side plate (3) and the horizontal plane is a right angle, and the angle between the conical side plate (2) and the horizontal plane is an acute angle. The top plate (11), the bottom plate (12), the conical side plate (2) and the cylindrical side plate (3) are connected to a cross-sectional support plate (4); the four corners of the bottom of each bottom plate (12) are respectively installed with a cubic foot (5); Each of the bottom plate (12) and the cross-section support plate (4) is provided with a circular hole (6) of the same size and shape; Among them: the shape of each reef body is a truncated cone with a height of 1 / 3 of the bottom plate width, and the conical side plate (2) set on the front face can relieve the strong flow velocity around the fan base (7), so that the streamline compression area of ​​the side wall of the fan base (7) is weakened, and the corresponding area with high flow velocity is dispersed, thereby increasing the range of the low pressure area around the fan base (7) and reducing the intensity, reducing the pressure difference around the fan base (7), and reducing the sand-carrying capacity of the water flow; on the other hand, the area of ​​biological attachment is increased, and the primary productivity and secondary productivity are improved; the water flow on the back face of the fan base (7) tends to be flat under the obstruction of the reef body, and the low-flow bottom water cannot reach the critical flow velocity for sediment initiation, and the scouring intensity and range around the fan base (7) are weakened.

2. The bottom-protected artificial reef for offshore wind farms according to claim 1, characterized in that: The number of the conical side panels (2) is one, the number of the cylindrical side panels (3) is one, the number of the cubic foot seats (5) is four, and the number of the cross-section support plate (4) is one and only one.

3. The bottom-protected artificial reef for offshore wind farms according to claim 1, characterized in that: The curvature of each of the annular horizontal plates (1) is , the curvature of the cylindrical side plate (3) is .

4. The bottom-protected artificial reef for offshore wind farms according to claim 1, characterized in that: There are multiple circular holes (6), and the cross-section support plate (4) is located on the symmetry axis of the main body, dividing the interior of the reef into two chambers of equal size.

5. The bottom-protected artificial reef for offshore wind farms according to claim 1, characterized in that: The shape of each reef body is truncated cone.

6. The bottom-protected artificial reef for offshore wind farms according to claim 1, characterized in that: Each of the reef bodies is cast by basalt composite bars and reinforced concrete.

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