Local thickening device and method for offshore three-pile foundation under action of reciprocating flow

Abstract

The invention discloses a local thickening device and method for an offshore three-pile foundation under the action of reciprocating flow. The local thickening device comprises a reinforcing frame and three thickening sleeves, wherein the three thickening sleeves are arranged on the outer sides of three pile foundations of the three-pile foundation in a sleeving mode correspondingly; the sealing assemblies are arranged at the two ends of the thickened sleeve to form sealed spaces; the fixing plate is arranged at the bottom end of the thickened sleeve and used for fixing the lower end of the thickened sleeve to the seabed. The flow guide cover is rotatably arranged on the outer side of the thickened sleeve in a sleeving manner; and a plurality of flow guide fins and an air guide mechanism. Vibration energy is absorbed through the annular gap filled with the flexible material between the thickened sleeve and the pile foundation, seabed scouring is restrained, and the foundation adaptability is improved; fixed fins and adjustable fins at the bottom of a flow guide cover automatically respond under the action of reciprocating flow, and the adjustable fins adaptively deflect to enable an air curtain nozzle to be perpendicular to the water flow direction all the time, so that a pile periphery vortex structure is efficiently damaged, and the scouring depth is remarkably reduced; the fixing plate integrates anchoring and counterweight functions and is combined with the flow guide cover to position the strong shear flow layer, so that precise vortex suppression and anti-overturning reinforcement are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind power substructures, in particular to a three-pile foundation, and more particularly to a device and method for locally thickening an offshore three-pile foundation under the action of a reciprocating flow. Background Art

[0002] Reciprocating current refers to a tidal current in which the rising and falling tides, caused by the influence of topography, are in opposite or nearly opposite directions. In the field of marine science and technology, it is considered a cyclical flow in which the tidal ellipse degenerates into a straight line.

[0003] Offshore wind power, as a clean, environmentally friendly, and renewable energy source, has seen significant growth in recent years. With the continuous advancement of wind power technology and the expansion of offshore wind farms into the deep sea, the construction of numerous offshore wind turbine piles has led to increasing attention for localized scour around the wind turbine pile foundations caused by wind, current, and wave loads. Scour occurs when the cylindrical structure alters the flow of water, forming a horseshoe-shaped vortex around the piles. This vortex pulls soil upward, causing soil loss around the piles and ultimately forming scour pits. Scour pits can severely impact the bearing capacity of the pile foundation and the vibration frequency of the wind turbine, resulting in significant losses.

[0004] Therefore, it is necessary to provide a device and method for locally thickening an offshore three-pile foundation under the action of reciprocating flow to solve the above technical problems. Summary of the Invention

[0005] The present invention overcomes the deficiencies of the prior art and provides a device and method for locally thickening an offshore three-pile foundation under the action of a reciprocating flow.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a device for locally thickening an offshore three-pile foundation under the action of reciprocating flow, which is used as an auxiliary for the three-pile foundation of an offshore wind turbine, comprising:

[0007] a reinforcement frame for connecting and supporting the three pile foundations;

[0008] Three thickened sleeves are respectively sleeved on the outside of the three pile foundations of the three pile foundations; wherein the inner diameter of the thickened sleeve is larger than the outer diameter of the corresponding pile foundation, so that an annular gap is formed between the thickened sleeve and the pile foundation;

[0009] Sealing components, provided at both ends of the thickened sleeve, for sealing both ends of the annular gap to form a sealed space;

[0010] a fixing plate, provided at the bottom end of the thickened sleeve, for fixing the lower end of the thickened sleeve to the seabed;

[0011] a connecting rod connecting the sealing assembly and the reinforcement frame;

[0012] A deflector cover is rotatably mounted on the outside of the thickened sleeve and close to the top of the thickened sleeve;

[0013] A plurality of guide fins are distributed in a circular array at the bottom of the guide cover;

[0014] and an air guide mechanism for generating an air bubble barrier perpendicular to the water flow direction.

[0015] In a preferred embodiment of the present invention, the air guide mechanism includes:

[0016] An air guide groove is provided on the circumferential wall of the air guide cover;

[0017] a plurality of nozzles evenly distributed on the outer peripheral wall of the air guide cover, wherein the inner ends of the nozzles are connected to the air guide grooves and the outer ends are provided with nozzles; and

[0018] External air supply equipment, used for injecting compressed air into the air guide groove through a pipeline;

[0019] In which, at least part of the guide fins are configured to adaptively adjust their flow angle according to the direction of water impact; and the nozzle angles of the multiple nozzles are synchronously adjusted as the flow angle of the adjustable guide fins changes, so that the nozzles are always facing a direction perpendicular to the direction of water impact.

[0020] In a preferred embodiment of the present invention, the sealing assembly includes:

[0021] A sealing ring is placed between the end of the thickened sleeve and the surface of the pile foundation;

[0022] A clamp is arranged on the outside of the thickened sleeve and presses the sealing ring to fix the sealing ring on the surface of the pile foundation.

[0023] In a preferred embodiment of the present invention, the annular space is filled with a filling material.

[0024] In a preferred embodiment of the present invention, the reinforcement frame includes:

[0025] The supporting part is used to connect with the lower end of the tower of the offshore wind turbine;

[0026] A plurality of fixing parts are arranged on the lower side of the supporting part;

[0027] Wherein, both ends of the connecting rod are respectively connected to the clamp and the fixing part.

[0028] In a preferred embodiment of the present invention, the axial length of the air guide cover is at least one third of the axial length of the thickened sleeve.

[0029] In a preferred embodiment of the present invention, the plurality of guide fins include:

[0030] The first flow guide fin is a semi-elliptical sheet structure fixedly arranged, and a large surface thereof is perpendicular to the axis of the flow guide cover;

[0031] The second flow guide fin is a flat plate structure rotatably arranged;

[0032] The first flow guide fin and the second flow guide fin are alternately and spacedly arranged along a circumference.

[0033] In a preferred embodiment of the present application, a plurality of the nozzles are uniformly arranged above the second flow guide fins, and the same number of nozzles correspond to each of the second flow guide fins.

[0034] In a preferred embodiment of the present application, the method further comprises:

[0035] The movable disc is arranged at a connecting end of the second flow guide fin and the flow guide cover;

[0036] The movable groove is arranged in the wall of the flow guide cover;

[0037] The transmission rod is arranged in the movable groove, and a lower end thereof is rotatably connected to a surface of the movable disc;

[0038] The nozzle is rotatably connected to the wall of the flow guide cover, and a side surface of the transmission rod is rotatably connected to an outer surface of each of the plurality of nozzles to form a linkage mechanism, so that an injection angle of an outer end of the nozzle relative to the axis of the flow guide cover is adjustable between 90° and 135°.

[0039] A method for locally thickening a three-pile foundation on the sea under reciprocating flow action, comprising the following steps:

[0040] S1, fixing a reinforcing frame to the seabed and connecting a wind turbine tower, installing thickening sleeves on the outer sides of the three pile foundations to form a sealed space, pouring filling materials, and anchoring the bottom end of the thickening sleeves to the seabed through a fixing plate;

[0041] S2, when the water flow impacts the flow guide fins, the second flow guide fin self-adaptively adjusts the flow-impingement angle according to the flow direction, so that the large surface of the fin is parallel to the water flow, and the first flow guide fin is driven to rotate the flow guide cover around the thickening sleeve by the tangential force;

[0042] S3, adjusting the injection angle of the nozzle to be perpendicular to the water flow direction through the linkage mechanism, starting the external air supply equipment to transport compressed air to the air guide groove, and forming a bubble barrier perpendicular to the water flow through the nozzle to destroy the vortex structure around the pile and suppress the seabed scouring.

[0043] In a preferred embodiment of the present application, the structure of S1 specifically comprises the following steps:

[0044] S11. According to the measured data, a thickened sleeve is installed at a designated position outside the pile foundation to form an annular gap;

[0045] S12. Install a sealing ring at the bottom of the sleeve, pour the filling material, install the top sealing ring and tighten the seal with a clamp;

[0046] S13. Drill holes at designated locations on the seabed, install pile foundations, and then anchor the bottom end of the thickened sleeve to the seabed via a fixing plate.

[0047] S14. Fix the supporting part of the reinforcement frame to the bottom of the wind turbine tower, connect the tower to the pile foundation using multiple beams, and then connect the clamp to the fixing part of the reinforcement frame using a connecting rod.

[0048] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0049] (1) The present invention provides a device for locally thickening an offshore three-pile foundation under the action of reciprocating flow. The device absorbs vibration energy by filling the annular gap between the thickened sleeve and the pile foundation with flexible material, thereby suppressing seabed scouring and improving foundation adaptability. The fixed fins and adjustable fins at the bottom of the guide cover respond autonomously under the action of reciprocating flow. The adaptive deflection of the adjustable fins keeps the air curtain nozzle perpendicular to the direction of the water flow, effectively destroying the vortex structure around the pile and significantly reducing the scouring depth. The fixed plate integrates the functions of anchoring and counterweight, and is combined with the guide cover to locate the strong shear flow layer, thereby achieving precise vortex suppression and anti-overturning reinforcement. The device forms a "buffer-diversion-vortex suppression" closed loop, solving the safety problem of the traditional three-pile foundation under the action of reciprocating flow, which forms horseshoe-shaped vortices around the piles and eventually forms scouring pits.

[0050] (2) The present invention presets an annular gap between the thickened sleeve and the pile foundation, and after filling it with flexible material, uses a sealing assembly consisting of a sealing ring and a clamp to seal both ends. At the same time, the reinforcement frame is rigidly connected to the clamp through a connecting rod to provide support for the tower outside the pile foundation. After this annular gap is filled with flexible material, a "flexible cushion layer" is formed, which can effectively absorb the vibration energy of the pile foundation under the action of wind, waves and currents. Its direct effect is to suppress the transmission of vibration energy to the seabed, avoiding the softening and accelerated erosion of the sediment layer caused by vibration. Compared with the technical solution of rigid contact between the traditional casing and the pile foundation, the present invention effectively solves the risk of stress concentration and weld cracking caused by rigid connection under complex wave loads. The adaptability of the pile foundation under complex hydrological conditions is significantly improved. The flexible materials such as the filled sand bag have the dual functions of counterweight and buffer, which synergistically extend the overall service life of the three-pile foundation.

[0051] (3)The application sets a circumferential array of fixed first guide fins and adjustable second guide fins at the bottom of the fairing, and uses a movable disc and a transmission rod to link the rotation of the second guide fins with the angle adjustment of the nozzle, so that the second guide fins can be deflected according to the direction of the water flow, the angle of the nozzle can be accurately calibrated, and the bubble barrier released by the nozzle can always impact the main flow direction vertically. The direct effect is to efficiently destroy the core structure of the horseshoe vortex around the pile, and significantly suppress the entrainment of the water flow to the seabed sediment. Compared with the passive protection devices such as grating and ballast block in the prior art, which cannot adapt to the change of the reciprocating flow direction and cause the fluctuation or even failure of the vortex suppression effect, the application can ensure that the coverage range of the air curtain accurately matches the vortex generation area, and significantly reduces the scour depth.

[0052] (4)The application designs a fixed plate and a fairing, the fixed plate is arranged at the bottom end of the thickened sleeve, and the fixed plate integrates a reinforcing rib and a counterweight area to realize the double protection of mechanical anchoring and counterweight anti-overturning; the axial length of the fairing is not less than one third of the length of the thickened sleeve, and the fairing is positioned close to the strong shear flow layer under the sea surface, and the bidirectional nozzle arranged at the top of the fairing can cover the key vortex suppression area of 0-3D (D is the pile diameter) around the pile foundation. The design directly enhances the anchoring stability of the thickened sleeve, and ensures that the air curtain can accurately act on the high-speed water flow and the vortex flow high-incidence area.

[0053] (5)The nozzle of the application is hinged with the fairing wall through trunnions, and the transmission rod transmits the deflection angle of the second guide fin to the nozzle according to a specific proportion, so that the jet angle of the outer end of the nozzle can be continuously adjusted within the range of 90° to 135°. The mechanism ensures that the jet direction of the nozzle can follow the flow direction change sensed by the second guide fin, and keeps vertical to the water flow impact direction in real time, maximizing the cutting efficiency of the bubble barrier to the vortex around the pile. Compared with the prior art scheme which relies on underwater sensors and electric actuators to adjust the angle of the nozzle, the pure mechanical linkage structure adopted by the application has no electronic components, has high environmental adaptability and reliability, and realizes maintenance-free operation in the whole life cycle. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, a brief introduction will be given below to the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings;

[0055] Figure 1 is a schematic diagram of the offshore three-pile foundation local thickening device of the preferred embodiment of the present application;

[0056] Figure 2 is a perspective view of the offshore three-pile foundation local thickening device of the preferred embodiment of the present application;

[0057] Figure 3 is a three-dimensional diagram of a thickened sleeve according to a preferred embodiment of the present invention;

[0058] Figure 4 is a cross-sectional view of a thickened sleeve according to a preferred embodiment of the present invention;

[0059] Figure 5 This is a three-dimensional structural diagram of a transmission rod according to a preferred embodiment of the present invention;

[0060] Figure 6 This is a flow chart of a method for locally thickening an offshore three-pile foundation according to a preferred embodiment of the present invention;

[0061] Figure 7 It is a flow chart of the structural installation method of the preferred embodiment of the present invention.

[0062] In the figure: 100, tower; 110, pile foundation; 200, reinforcement frame; 210, supporting part; 220, fixing part; 300, thickened sleeve; 310, annular gap; 320, filling material; 400, sealing assembly; 410, sealing ring; 420, clamp; 500, fixing plate; 510, screw; 600, connecting rod; 700, air guide cover; 710, movable disk; 720, transmission rod; 800, guide fin; 810, first guide fin; 820, second guide fin; 900, air guide mechanism; 910, nozzle; 930, nozzle. DETAILED DESCRIPTION

[0063] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0064] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0065] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0066] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0067] The types of offshore wind turbine foundations include gravity, single pile, tripod (multi-pile), jacket, negative pressure barrel, floating, etc. This application specifically refers to a three-pile foundation, that is, a tripod foundation, similar to the tripod foundation commonly used in small oil and gas production platforms. The lightweight and economical tripod steel casing has some steel frames distributed on the pile foundations under the tower, which bear the pressure of the tower on the three pile foundations respectively. Due to soil conditions and freezing load restrictions, small diameter steel piles and tubular steel structures are used, as well as filling or forming connection methods. The tripod enhances the rigidity and strength of the structure, and the central axis of the tripod provides basic support for the wind turbine tower.

[0068] Figure 1A schematic diagram of a local thickening device for a three-pile foundation 110 under reciprocating flow is shown in the embodiment. The three-pile foundation 110 includes three pile foundations 110, which are divided into two sections, the upper section being below the sea level and above the seabed, and the lower section being inserted into the hole drilled in the seabed and fixed to the seabed by pouring mortar, cementing riprap, and other materials. The pile foundations 110 are connected to each other by cross beams and fixedly connected to the lower end of the tower 100 to support the tower 100, and the upper end of the tower 100 extends above the sea level and is installed with a wind turbine generator. In addition, the length and diameter of the pile foundations 110 and the tower 100 are appropriately determined based on the scale of the offshore wind turbine generator to be supported, the installation sea area, the condition of the sediment layer, and the like.

[0069] The application provides a local thickening device for a three-pile foundation 110 under reciprocating flow, which is used for assisting a three-pile foundation 110 for an offshore wind turbine generator, and includes a reinforcing frame 200, a thickening sleeve 300, a sealing assembly 400, a fixing plate 500, a connecting rod 600, a flow guide cover 700, a flow guide fin 800, and a gas guide mechanism 900.

[0070] Figure 3 A perspective view of the thickening sleeve is shown, Figure 4A cross-sectional view of the thickened sleeve is shown. Specifically, the reinforcement frame 200 is used to connect and support the three pile foundations 110; the three thickened sleeves 300 are respectively sleeved on the outer side of the upper section of the pile foundation 110 of the three pile foundations 110, that is, the part above the seabed. The inner diameter of the thickened sleeve 300 is larger than the outer diameter of the corresponding pile foundation 110, so that an annular gap 310 is formed between the thickened sleeve 300 and the pile foundation 110. The difference between the inner diameter of the thickened sleeve 300 and the outer diameter of the pile foundation 110 is not particularly limited, but when the axis of the cylinder coincides with the axis of the pile foundation 110, the distance between the inner wall surface of the thickened sleeve 300 and the outer periphery of the cylinder 110 is preferably 5 cm or more and 30 cm or less, more preferably 8 cm or more and 20 cm or less, and even more preferably 10 cm or more and 15 cm or less. If the distance is less than 5 cm, it is difficult to pass the pile foundation 110 through the hole of the thickened sleeve 300. If the distance exceeds 30 cm, the pile foundation 110 may tilt inside the thickened sleeve 300, and it is difficult to seal the annular gap 310, which poses a great construction risk. In addition, in this local thickening device, when the distance is more than 10 cm, any filling material 320 can be filled in the annular gap 310. The filling material 320 is not particularly limited, but sand bags or sandbags are preferably used. Since sand bags and sandbags have irregular shapes and can be deformed under external forces, they are suitable as filling materials 320 in the annular gap 310. In addition, when the pile foundation 110 sways due to the influence of offshore wind turbine blades, it can absorb the shaking caused by rotation, waves, ocean currents, etc. By preventing and suppressing the vibration of the pile foundation 110, the state of the surrounding sediment layer can be prevented from being softened by the vibration of the pile foundation 110.

[0071] Sealing assemblies 400 are disposed at both ends of the thickened sleeve 300, closing both ends of the annular gap 310 to form a sealed space. The sealing assembly 400 comprises a sealing ring 410 and a clamp 420. The material of the sealing ring 410 is not particularly limited; any flexible material suitable for underwater environments is sufficient, preferably a flexible rubber material. The sealing ring 410 is positioned between the end of the thickened sleeve 300 and the surface of the pile foundation 110, forming a flexible connection between the thickened sleeve 300 and the pile foundation 110 and absorbing vibrations from the pile foundation 110. The clamp 420 is disposed outside the thickened sleeve 300 and compresses the sealing ring 410, securing it to the surface of the pile foundation 110. When the pile foundation 110 inevitably tilts slightly due to wind and wave impact, the annular gap 310 can temporarily accommodate the deviation of the pile foundation 110, preventing direct, rigid collision between the thickened sleeve 300 and the pile foundation 110. At this time, the thickened sleeve 300 acts as a "reaction wall" to provide reverse support force, and the air layer in the annular gap 310 plays the role of a buffer transition zone, delaying the transmission of the tilt to the sediment layer.

[0072] The fixing plate 500, located at the bottom end of the thickened sleeve 300, is used to secure the lower end of the thickened sleeve 300 to the seabed. The fixing plate 500 is a disc-shaped structure with several mounting holes on its surface. Alloy screws 510 are used to anchor the thickened sleeve 300 to the seabed. Furthermore, a plurality of reinforcing ribs are provided on the upper surface of the fixing plate 500 to enhance the connection strength between the fixing plate 500 and the thickened sleeve 300. Furthermore, the upper surface of the fixing plate 500 is provided with one or more areas (not shown) for accommodating heavy objects. Heavy objects, including stones, gravel, metal, concrete blocks, etc., can be piled in these areas to increase the stability of the thickened sleeve 300.

[0073] Figure 2 A three-dimensional diagram of the local thickening device for an offshore three-pile foundation is shown. The reinforcement frame 200 comprises a supporting portion 210 and multiple fixing portions 220. The supporting portion 210 is used to connect to the lower end of the offshore wind turbine tower 100. Multiple fixing portions 220 are located on the underside of the supporting portion 210. The connecting rod 600 connects the clamp 420 and the fixing portion 220 at each end. It should be noted that the supporting portion 210 is a regular triangular steel plate platform with a central flange interface that bolts to the bottom flange of the tower 100. The non-connected area is curved downward to prevent the accumulation of mud and sand on the surface of the supporting portion 210. Three main beams extend from the edge of the supporting portion 210. Each main beam end is welded to the crossbeam of the three-pile foundation 110. The fixing portions 220 are provided on the surface of the main beams, which also serve as flange interfaces. The connecting rod 600 is fixedly connected to the clamp 420 via the flange connection. The reinforcement frame 200 evenly transfers the load of the tower 100 to the three pile foundations 110 to avoid local stress concentration, and provides a second support for the tower 100 in addition to the pile foundations 110, so that the tower 100 has higher stability.

[0074] In this embodiment, the air deflector 700 is rotatably mounted on the outside of the thickened sleeve 300, and the air deflector 700 is close to the top of the thickened sleeve 300; it should be noted that the air deflector 700 can be rotated by a ceramic bearing mounted on the outside of the thickened sleeve 300, or a circular track can be set on the surface of the thickened sleeve 300, and multiple rollers / balls are set on the upper end of the air deflector 700, and the rotation of the air deflector 700 is achieved by the movable characteristics of the rollers / balls in the circular track. The axial length of the fairing 700 is at least one-third of the axial length of the thickened sleeve 300. The fairing 700 is close to the top of the thickened sleeve 300, that is, away from the seabed sediment disturbance zone, reducing the risk of the transmission mechanism being blocked by silt, and the ocean reciprocating flow forms the strongest shear flow layer 1-3 meters below the water surface. The closer to the seabed, the smoother the water flow. The fairing 700 is in the top area of ​​the thickened sleeve 300, and is close to the strong shear flow layer, which can directly intercept high-speed water flow and maximize the destructive effect of the air curtain on the vortex core area.

[0075] In this embodiment, a plurality of guide fins 800 are welded in a circular array on the bottom of the guide cover 700. The number of guide fins 800 is at least 8. The guide fins 800 drive the guide cover 700 to rotate around the thickened sleeve 300 by bearing the impact of the water flow.

[0076] In this embodiment, the air guide mechanism 900 includes: an air guide groove, multiple nozzles 910, and an external air supply device; wherein the air guide groove is provided on the circumferential wall of the deflector 700; multiple nozzles 910 are evenly distributed on the outer peripheral wall of the deflector 700; the inner ends of the nozzles 910 are connected to the air guide groove via flexible air pipes, and the outer ends are provided with conical diffusion nozzles 930. The nozzles 930 are divided into two parts, one vertically upward and the other vertically downward when the nozzles 910 are horizontal; the external air supply device is used to inject compressed air into the air guide groove through a pipeline; wherein the model of the external air supply device is not particularly limited, for example, an air compressor is installed on the tower 100 and powered by a wind turbine. The arrangement of the air guide mechanism 900 in the local thickening device forms an air curtain layer by injecting compressed air into the air guide groove through the bidirectional conical diffusion nozzles 930 at the ends of the nozzles 910. When the air compressor on tower 100 supplies an air pressure of 0.8-1.2 MPa, the 0.5-2 mm microbubbles released from nozzle 930 form a turbulent gas-liquid two-phase flow barrier. This bubble curtain disrupts the water boundary layer through a turbulent kinetic energy dissipation mechanism dominated by Reynolds stress, shifting the separation point around pile foundation 110 backward. Under the action of bidirectional nozzle 930, the upward-spraying bubble cluster suppresses the reverse vortex near the water surface, while the downward-spraying bubble cluster penetrates to a 3D area (D is the diameter of the pile foundation) above the seabed, weakening the horseshoe vortex's entrainment of the sediment layer.

[0077] Among them, at least part of the guide fins 800 are configured to adaptively adjust their incident angle according to the direction of water flow impact. Specifically: the multiple guide fins 800 include: a first guide fin 810 and a second guide fin 820; the first guide fin 810 is a fixed semi-elliptical sheet structure, whose large surface is perpendicular to the axis of the guide cover 700, to meet the impact of underwater water flow, and drive the guide cover 700 to rotate around the thickened sleeve 300; and the second guide fin 820 is a rotatable flat plate structure. When the underwater water flow impacts the second guide fin 820, it is subjected to a tangential force, causing the second guide fin 820 to adaptively adjust its incident angle according to the flow direction, so that the large surface of the fin is parallel to the water flow, and the first guide fin 810 and the second guide fin 800 are distributed alternately along the circumference.

[0078] Furthermore, the angles of the nozzles 930 of the multiple nozzles 910 are adjusted synchronously with the angle of flow of the adjustable guide fins 800, ensuring that the nozzles 930 are always oriented perpendicular to the direction of water flow. The multiple nozzles 910 are evenly distributed in the area directly above the second guide fins 800, with the same number of nozzles 910 corresponding to each second guide fin 800. Figure 5 A three-dimensional structural diagram of the transmission rod is shown. The local thickening device also includes: a movable disk 710, a movable groove and a transmission rod 720; the movable disk 710 is arranged on the surface of the connecting axis between the second guide fin 800 and the guide cover 700, and rotates as the second guide fin 800 rotates; the movable groove is opened on the wall of the guide cover 700, and the transmission rod 720 moves in the movable groove, and its lower end is rotatably connected to the surface of the movable disk 710. Among them, the nozzle 910 is rotatably connected to the wall of the guide cover 700 through an ear shaft; the side of the transmission rod 720 is rotatably connected to the outer surface of multiple nozzles 910, forming a linkage mechanism; so that the injection angle of the outer end of the nozzle 910 relative to the axis of the guide cover 700 is adjustable between 90° and 135°. It should be noted that the connection position between the transmission rod 720 and the movable disk 710 is set according to the size of the nozzle 910 and the size of the movable disk 710, so that the connection point rotates half a circle with the movable disk 710, from the highest point to the lowest point, driving the nozzle 910 to adjust the angle by a maximum of 45° to adapt to the oblique water flow impact that may be generated under the action of reciprocating flow and the influence of the three pile foundations 110, so that the nozzle 930 is always facing in a direction perpendicular to the direction of water flow impact, and after being ejected from the nozzle 930, a bubble barrier perpendicular to the main water flow is formed, thereby maximizing the vortex destruction effect of the bubble barrier.

[0079] It is worth noting that a bearing is provided on the surface of the connecting shaft of the second guide fin 800 , the outer ring of the bearing is fixedly connected to the guide cover 700 , and the movable disk 710 is free to rotate in the movable groove.

[0080] The present invention sets a circumferential array of fixed first guide fins 810 and adjustable second guide fins 800 at the bottom of the deflector 700, and uses a movable disk 710 and a transmission rod 720 to link the rotation of the second guide fins 800 with the angle adjustment of the nozzle 910. This allows the second guide fins 800 to adaptively deflect according to the direction of the water flow, accurately calibrates the injection angle of the nozzle 910 to 0°-45°, and ensures that the bubble barrier released by the nozzle 930 always impacts the mainstream direction vertically. Its direct effect is to efficiently destroy the core structure of the horseshoe vortex around the pile and significantly inhibit the suction effect of the water flow on the seabed sediments. Compared with the shortcomings of passive protective devices such as grids and ballast blocks in the existing technology that cannot adapt to changes in the direction of the reciprocating flow, resulting in fluctuations in the vortex suppression effect or even failure, the present invention can ensure that the air curtain coverage area accurately matches the vortex generation area, significantly reducing the scouring depth.

[0081] It is worth noting that the bubble barrier released by nozzle 930 always impacts the mainstream direction perpendicularly, ensuring that the bubble barrier accurately cuts into the core area of ​​the horseshoe vortex around the pile, maximizing the turbulent energy dissipation effect - the vertical impact can strongly disrupt the water flow structure, causing the boundary layer separation point to shift backward, directly destroying the vortex's suction effect on seabed sediments, thereby significantly suppressing the scouring depth. If the bubble barrier fails to be perpendicular to the mainstream, the bubble group will deviate from the high vortex intensity area, and the vortex suppression effect will be greatly weakened: when the reciprocating flow changes direction, the inclined bubble curtain only covers the local flow field, unable to penetrate the vortex generation area, and it is difficult to interfere with the strong shear flow layer, causing the scouring pit around the pile to continue to deepen.

[0082] Figure 6 The present embodiment shows a method for locally thickening three pile foundations 110 at sea under the action of a reciprocating flow. The method for locally thickening three pile foundations 110 comprises the following steps:

[0083] Step S1: Fix the reinforcement frame 200 to the seabed and connect it to the wind turbine tower 100. After installing the thickened sleeve 300 outside the three pile foundations 110 to form a sealed space, pour the filling material 320 and anchor the bottom end of the thickened sleeve 300 to the seabed through the fixing plate 500.

[0084] Step S2: When the water flow hits the guide fin 800, the rotatable second guide fin 800 adaptively adjusts the flow angle according to the flow direction so that the large surface of the fin is parallel to the water flow, and the fixed first guide fin 810 is subjected to the tangential force to drive the deflector 700 to rotate around the thickened sleeve 300.

[0085] Step S3: In step S2, the second guide fin 800 adaptively adjusts the angle of attack based on the flow direction. During this process, the movable disc 710 driven by the rotating shaft of the second guide fin 800 drives the transmission rod 720 to vertically displace, forcing the nozzle 910 to deflect around the center of the trunnion. A linkage mechanism ensures that the axis of the nozzle 930 of the nozzle 910 remains perpendicular to the measured flow direction. An external air supply device delivers compressed air to the air guide slot, and a group of bubbles is ejected through the upper and lower bidirectional nozzles 930 of the nozzle 910. The bubble curtain of the upper nozzle 930 suppresses the adverse pressure gradient vortex in the 0-2D depth range of the water surface. The bubble curtain of the lower nozzle 930 penetrates the 3D region above the seabed to interfere with the formation of horseshoe vortices, synchronously shifting the boundary layer separation point of the pile foundation 110 backward.

[0086] Figure 7 The flow chart of the structure installation method is shown. The structure installation of step S1 specifically includes the following steps:

[0087] Step S11 , based on the measured data of the depth and exposed size of the pile foundation 110 in the seabed, a thickened sleeve 300 is installed from top to bottom at a designated position outside the upper section of the pile foundation 110 to form an annular gap 310 of 5 to 30 cm.

[0088] Step S12: Install the sealing ring 410 at the bottom of the sleeve, pour the filling material 320, install the top sealing ring 410 and press and seal it with the clamp 420.

[0089] Step S13: Drill installation holes for the pile foundation 110 at the pre-explored seabed coordinate points, insert the lower sections of the three pile foundations 110 into the holes, and pour high-strength sulphoaluminate cement mortar or other materials to fix them. After the pile foundation 110 is installed, the bottom end of the thickened sleeve 300 is anchored to the seabed through the fixing plate 500. Optionally, the surface of the fixing plate 500 is loaded with concrete counterweights with a single mass of 1.5 tons to enhance anti-overturning stability.

[0090] Step S14: Fix the supporting portion 210 of the reinforcement frame 200 to the bottom of the wind turbine tower 100 with bolts, connect the tower 100 to the pile foundation 110 with multiple beams, and then connect the clamp 420 to the fixing portion 220 of the reinforcement frame 200 with a connecting rod 600.

[0091] The above description is based on the ideal embodiment of the present invention. Based on the above description, relevant personnel can make various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the content of the specification and must be determined according to the scope of the claims.

Claims

1. A device for locally thickening an offshore three-pile foundation under the action of reciprocating flow, which is used as an auxiliary for the three-pile foundation of an offshore wind turbine, characterized in that: include: a reinforcement frame for connecting and supporting the three pile foundations; Three thickened sleeves are respectively sleeved on the outside of the three pile foundations of the three pile foundations; wherein the inner diameter of the thickened sleeve is larger than the outer diameter of the corresponding pile foundation, so that an annular gap is formed between the thickened sleeve and the pile foundation; Sealing components, provided at both ends of the thickened sleeve, for sealing both ends of the annular gap to form a sealed space; a fixing plate, provided at the bottom end of the thickened sleeve, for fixing the lower end of the thickened sleeve to the seabed; a connecting rod connecting the sealing assembly and the reinforcement frame; A deflector cover is rotatably mounted on the outside of the thickened sleeve and close to the top of the thickened sleeve; A plurality of guide fins are distributed in a circular array at the bottom of the guide cover; and an air guide mechanism for generating an air bubble barrier perpendicular to the water flow direction.

2. The device for locally thickening three-pile foundation at sea under the action of reciprocating flow according to claim 1, characterized in that: The air guide mechanism comprises: An air guide groove is provided on the circumferential wall of the air guide cover; a plurality of nozzles evenly distributed on the outer peripheral wall of the air guide cover, wherein the inner ends of the nozzles are connected to the air guide grooves and the outer ends are provided with nozzles; and External air supply equipment, used for injecting compressed air into the air guide groove through a pipeline; In which, at least part of the guide fins are configured to adaptively adjust their flow angle according to the direction of water impact; and the nozzle angles of the multiple nozzles are synchronously adjusted as the flow angle of the adjustable guide fins changes, so that the nozzles are always facing a direction perpendicular to the direction of water impact.

3. The device for locally thickening three-pile foundation at sea under the action of reciprocating flow according to claim 1, characterized in that: The sealing assembly comprises: A sealing ring is placed between the end of the thickened sleeve and the surface of the pile foundation; A clamp is arranged on the outside of the thickened sleeve and presses the sealing ring to fix the sealing ring on the surface of the pile foundation.

4. The device for locally thickening three-pile foundation at sea under the action of reciprocating flow according to claim 3, characterized in that: The reinforcement frame comprises: The supporting part is used to connect with the lower end of the tower of the offshore wind turbine; A plurality of fixing parts are arranged on the lower side of the supporting part; Wherein, both ends of the connecting rod are respectively connected to the clamp and the fixing part.

5. The device for locally thickening three-pile foundation at sea under the action of reciprocating flow according to claim 1, characterized in that: The axial length of the air guide cover is at least one third of the axial length of the thickened sleeve.

6. The device for locally thickening three-pile foundation at sea under the action of reciprocating flow according to claim 1, characterized in that: The plurality of guide fins include: The first guide fin is a fixed semi-elliptical sheet structure, with its large surface perpendicular to the axis of the guide cover; The second guide fin is a rotatable flat plate structure; The first guide fins and the second guide fins are distributed alternately along the circumference.

7. The device for locally thickening three-pile foundation at sea under the action of reciprocating flow according to claim 2, characterized in that: The plurality of nozzles are evenly distributed in the area directly above the second guide fins, and the same number of nozzles are correspondingly located above each of the second guide fins.

8. The device for locally thickening three-pile foundation at sea under the action of reciprocating flow according to claim 2, characterized in that: Also includes: a movable plate, provided at the connection end between the second guide fin and the guide cover; A movable groove is provided on the wall of the air guide cover; a transmission rod, disposed in the movable groove, with its lower end rotatably connected to the surface of the movable disk; The nozzle is rotatably connected to the wall of the shroud; the side surfaces of the transmission rod are rotatably connected to the outer surfaces of multiple nozzles, forming a linkage mechanism, so that the injection angle of the outer end of the nozzle relative to the axis of the shroud can be adjusted between 90° and 135°.

9. A method for locally thickening a three-pile foundation at sea under the action of a reciprocating flow, based on a device for locally thickening a three-pile foundation at sea under the action of a reciprocating flow according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Fix the reinforcement frame to the seabed and connect it to the wind turbine tower. Install a thickened sleeve outside the three pile foundations to form a sealed space. Pour the filling material and anchor the bottom of the thickened sleeve to the seabed using a fixing plate. S2. When the water flow hits the guide fin, the second guide fin adaptively adjusts the angle of attack according to the flow direction, so that the large surface of the fin is parallel to the water flow. The first guide fin is subjected to the tangential force, which drives the guide cover to rotate around the thickened sleeve. S3. Adjust the nozzle spray angle to be perpendicular to the water flow direction through the linkage mechanism, start the external air supply equipment to deliver compressed air to the air guide groove, and form a bubble barrier perpendicular to the water flow through the nozzle to destroy the vortex structure around the pile and suppress seabed scouring.

10. The method for local thickening of an offshore three-pile foundation under the action of reciprocating flow according to claim 9, characterized in that: The structural installation of S1 specifically includes the following steps: S11. According to the measured data, a thickened sleeve is installed at a designated position outside the pile foundation to form an annular gap; S12. Install a sealing ring at the bottom of the sleeve, pour the filling material, install the top sealing ring and tighten the seal with a clamp; S13. Drill holes at designated locations on the seabed, install pile foundations, and then anchor the bottom end of the thickened sleeve to the seabed via a fixing plate. S14. Fix the supporting part of the reinforcement frame to the bottom of the wind turbine tower, connect the tower to the pile foundation using multiple beams, and then connect the clamp to the fixing part of the reinforcement frame using a connecting rod.

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