Offshore wind turbine split type jacket foundation structure and flange and grouting combined connection method

Abstract

The invention discloses an offshore wind turbine split type jacket foundation structure and a flange and grouting combined connection method. The offshore wind turbine split type jacket foundation structure comprises a lower jacket, and steel pipe piles are fixed to the bottom of the lower jacket; a tower drum frame is mounted at the top of the upper jacket, and the upper jacket is mounted at the top of the lower jacket; the inserting tip comprises a connecting steel pipe and a guide device, the connecting steel pipe is integrally located in the lower jacket, a lower flange plate is arranged at the top of the connecting steel pipe, a sealer is arranged at the bottom of the connecting steel pipe, and a grouting cavity is formed between the top of the lower jacket and the sealer; the flange connecting mechanism is arranged at the bottom of the upper jacket and the top of the connecting steel pipe; the grouting cavity is provided with a grouting hole and an overflow hole, and a fixing assembly is installed on the connecting steel pipe. Flange plate-grouting connection has the advantages of being convenient to construct and high in tolerance, and can be conveniently applied to the severe ocean construction environment.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind power engineering, and in particular to a split-type jacket foundation structure for an offshore wind turbine and a flange and grouting combined connection method. Background Art

[0002] As a key pillar of energy transformation, offshore wind power is rapidly expanding into deep-sea areas and continuously advancing the development of larger single-unit capacity. Traditional monolithic jacket structures face significant challenges in the construction of deep-sea wind farms due to their size and weight increasing dramatically with water depth and turbine capacity, exceeding the carrying capacity limits of conventional transport vessels and installation equipment. Dividing the jacket foundation structure into two separate parts, transporting each to the offshore construction site for assembly, effectively circumvents the size and weight limitations of overall transportation and hoisting, and reduces the requirements for shipboard equipment capabilities. However, this technical approach presents a new challenge: how to quickly connect the two parts in the harsh marine construction environment.

[0003] Grouting connections are often used for on-site connections of large steel structures in marine engineering due to their excellent installation tolerance and ease of construction. They connect two steel pipes by filling the cavity between the walls of two circular-section steel pipes of different diameters with high-strength grouting material. Grouting can also be used to connect the upper and lower structures of offshore wind turbine jackets. However, due to the tilt of the jacket's main limbs, the inner steel pipe (also known as the insert) cannot be directly inserted into the outer steel pipe (also known as the sleeve) at the same time. Both the utility model with application number 202321456517.2 and the utility model with application number 202321295737.1 bend the main limbs into a vertical position at the grouting connection to facilitate construction. However, while bending the jacket's main limbs increases manufacturing difficulty, it can also lead to bending and stress concentration in the main limbs of the structure, resulting in a decrease in the overall stiffness and load-bearing capacity of the structure.

[0004] Based on the above technical problems, the present invention provides a split-type jacket foundation structure for an offshore wind turbine and a flange and grouting combined connection method. Summary of the Invention

[0005] The purpose of the present invention is to provide a split-type jacket foundation structure for an offshore wind turbine and a flange and grouting combined connection method to solve the problems existing in the prior art.

[0006] To achieve the above-mentioned object, the present invention provides the following solution: The present invention provides a split-type jacket foundation structure for an offshore wind turbine, comprising:

[0007] A lower jacket frame, wherein a steel pipe pile is fixed at the bottom of the lower jacket frame;

[0008] An upper jacket, a tower frame is installed on the top of the upper jacket, and the upper jacket is installed on the top of the lower jacket;

[0009] The plug tip includes a connecting steel pipe and a guide device. The connecting steel pipe is entirely located inside the lower conductor frame. A lower flange is provided on the top of the connecting steel pipe, and a sealer is provided on the bottom. A grouting cavity is formed between the top of the lower conductor frame and the sealer.

[0010] A flange connection mechanism, the flange connection mechanism being arranged at the bottom of the upper jacket and the top of the connecting steel pipe, and being used to connect the upper jacket and the connecting steel pipe;

[0011] The grouting cavity is provided with a grouting hole and an overflow hole, and a fixing assembly is installed on the connecting steel pipe. According to the present invention, the upper jacket comprises a plurality of first supporting main legs, adjacent first supporting main legs being fixed by first diagonal braces, piles being fixed to the tops of the first supporting main legs, and the tower frame being fixed to the top surfaces of the piles.

[0012] According to the offshore wind turbine split jacket foundation structure provided by the present invention, the lower jacket includes a plurality of second support main legs, the first support main legs and the second support main legs are arranged in a one-to-one correspondence, the top end of the connecting steel pipe is inserted into the bottom end of the first support main leg, and the bottom end of the connecting steel pipe is inserted into the top end of the second support main leg. Adjacent second support main legs are fixed by second diagonal braces and horizontal braces, and the bottom end of the second support main leg is fixed to the steel pipe pile;

[0013] According to the offshore wind turbine split jacket foundation structure provided by the present invention, the flange connection mechanism includes an upper flange and a lower flange, the upper flange is fixed to the bottom of the first supporting main leg, and the lower flange is fixed to the top of the connecting steel pipe, the upper flange is provided with a plurality of first bolt holes at equal intervals in the circumferential direction, and the lower flange is provided with a plurality of second bolt holes at equal intervals in the circumferential direction, the first bolt holes and the second bolt holes are arranged in a one-to-one correspondence, a positioning bolt is inserted between the first bolt hole and the second bolt hole, and one end of the positioning bolt is fixed by a nut.

[0014] According to the offshore wind turbine split-type jacket foundation structure provided by the present invention, two groups of fixing components are provided, both of which are arranged on the connecting steel pipe and located in the grouting cavity, and the fixing components include guide limit blocks, and several groups of guide limit blocks are fixed on the outer wall of the connecting steel pipe at equal intervals in the circumferential direction.

[0015] According to the offshore wind turbine split-type jacket foundation structure provided by the present invention, the sealer includes a sealing ring, and the sealing ring is fixed to the outer wall of the bottom end of the connecting steel pipe.

[0016] According to the offshore wind turbine split jacket foundation structure provided by the present invention, several groups of circumferential shear keys are fixed to the outer wall of the connecting steel pipe and the inner wall of the lower jacket, and the circumferential shear keys are staggered and arranged at equal intervals along the axis of the connecting steel pipe.

[0017] According to the offshore wind turbine split jacket foundation structure provided by the present invention, a guide device is fixed to the bottom end of the connecting steel pipe, and the guide device is inserted into the second supporting main leg.

[0018] A flange and grouting combined connection method for a split-type jacket foundation structure of an offshore wind turbine comprises the following steps:

[0019] Step 1: Prefabrication of components in factory

[0020] During the factory fabrication phase, the connecting steel pipe is placed within the lower jacket using a guide device and initially secured to the lower jacket via a lower flange. Temporary supports or spot welding can be used to secure the relative position of the two. Once secured, the upper flange at the bottom of the upper jacket and the lower flange at the top of the lower jacket are pre-assembled in the factory, ensuring that the angles and positions meet design requirements. Finally, the sections are transported to the offshore construction platform.

[0021] Step 2: Install and secure the lower jacket and the plug tip. Secure the lower jacket and its internal connecting steel pipes to the seabed through steel pipe piles at their bottom. Use piling equipment to drive the steel pipe piles into the seabed to a specified depth, ensuring that the lower jacket is securely installed and positioned accurately, and that its top is level as designed.

[0022] Step 3: hoisting the upper jacket and preliminary connection of flanges;

[0023] Use large-scale lifting equipment to slowly lift the upper jacket to the top of the lower jacket. Keep the upper jacket stable during the lifting process, so that the bottom surface of the upper flange is aligned with the top surface of the lower flange. Clean the debris and stains on the flange surface to ensure that the flange surface is flat and fits well. Adjust the angle to pass the positioning bolts through the bolt holes, and preliminarily tighten the bolts to achieve the initial connection and fixation of the upper and lower jackets.

[0024] Step 4: Grouting:

[0025] Check whether the grouting holes and overflow holes of the grouting cavity are unobstructed and ensure that there is no blockage. According to the seawater environment and load-bearing requirements, select a slurry with good fluidity, seawater erosion resistance and high strength, and mix it according to the specified ratio. Slowly pour the slurry into the grouting cavity through the grouting holes, controlling the pouring speed to avoid slurry segregation or bubble generation due to excessive pouring speed. Until the slurry overflows evenly from the overflow hole, indicating that the grouting cavity is full, close the grouting holes and overflow hole, and cure the slurry in the grouting cavity according to the slurry curing requirements.

[0026] Step 5: Final tightening of the flange connection mechanism;

[0027] After grouting is completed, the bolts of the flange connection mechanism are finally tightened; according to the specified tightening sequence and torque requirements, all bolts are tightened step by step and evenly to ensure that the flange connection is tight and the force is evenly distributed, so that the upper and lower jackets are firmly connected through the flange connection mechanism;

[0028] Step 6: Quality inspection and acceptance;

[0029] Conduct a comprehensive quality inspection on the entire flange and grouting combined connection structure, including the tightness of the flange connection, whether the bolt torque meets the requirements, the slurry fullness and strength of the grouting cavity meet the standards, and whether the fixed components are firmly installed; if any problems are found, make timely corrections until all inspection items meet the design and specification requirements.

[0030] The present invention discloses the following technical effects:

[0031] 1) The present invention adopts a split design, and the lower and upper jackets can be prefabricated, transported and installed separately, which reduces the weight and size of a single hoisting operation. It is suitable for small and medium-sized hoisting equipment, reduces dependence on large-scale offshore construction equipment, and improves construction flexibility and convenience. It is particularly suitable for complex marine environments.

[0032] 2) The present invention adopts flange grouting combination connection, and the flange connection provides initial reliable positioning and mechanical fastening. The double grouting cavity forms an integral force-bearing structure after the high-strength slurry is cured, which greatly improves the connection stiffness and bearing capacity of the upper and lower conductor frames, and can effectively resist the vertical load, horizontal wind and wave load and torque during the operation of the offshore wind turbine.

[0033] 3) The sealer at the bottom of the plug tip of the present invention, combined with the sealing effect of the grouting cavity slurry after solidification, can effectively prevent impurities such as seawater and mud from invading the connection part, avoiding damage to the internal structure due to corrosion or wear. At the same time, the double grouting cavity design further enhances the sealing redundancy and improves the anti-seepage performance of the structure.

[0034] 4) The grouting material is a special slurry that is resistant to seawater erosion. Combined with the metal structure protection of the flange connection, it can adapt to the harsh environment of high humidity and high salt fog at sea, reduce structural degradation during long-term use, and extend the service life of the equipment.

[0035] 5) During the construction process, the horizontality and coaxiality can be adjusted by pre-tightening the flange bolts. The step-by-step positioning and tightening process before grouting can accurately control the connection accuracy, ensure the coaxiality and verticality of the upper and lower jackets and plug tips, and lay a stable foundation for the subsequent tower frame installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only 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.

[0037] Figure 1 This is an overall schematic diagram of the split-type jacket support structure;

[0038] Figure 2 This is a schematic diagram of the upper jacket and wind turbine tower frame;

[0039] Figure 3 This is a schematic diagram of the lower jacket and steel pipe piles;

[0040] Figure 4 This is a schematic diagram of the flange-grouting combined connection section of the present invention;

[0041] Figure 5 It is a schematic diagram of the upper flange of the present invention;

[0042] Figure 6 It is a schematic diagram of the lower flange of the present invention.

[0043] Among them, 1. Tower frame; 2. Upper conductor frame; 201. First supporting main leg; 202. First diagonal brace; 3. Lower conductor frame; 301. Second supporting main leg; 302. Second diagonal brace; 303. Horizontal brace; 304. Overflow hole; 305. Guide limit block; 306. Circumferential shear key; 307. Grouting hole; 308. Sealing ring; 309. Grouting cavity; 310. Guide device; 311. Bolt; 4. Steel pipe pile; 5. Upper flange; 501. First bolt hole; 6. Lower flange; 601. Second bolt hole; 7. Connecting steel pipe. DETAILED DESCRIPTION

[0044] 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.

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Reference Figures 1-6 The present invention provides a split-type jacket foundation structure for an offshore wind turbine, comprising:

[0047] A lower jacket frame 3, with steel pipe piles 4 fixed at the bottom of the lower jacket frame 3;

[0048] An upper jacket frame 2, on the top of which a tower frame 1 is installed, and the upper jacket frame 2 is installed on the top of a lower jacket frame 3;

[0049] The plug tip includes a connecting steel pipe 7 and a guide device 310. The connecting steel pipe is entirely located inside the lower jacket 3. A lower flange 6 is provided on the top of the connecting steel pipe 7, and a sealer is provided on the bottom. A grouting cavity 309 is formed between the top of the lower jacket 3 and the sealer.

[0050] A flange connection mechanism is provided at the bottom of the upper jacket frame 2 and the top of the connecting steel pipe 7, and is used to connect the upper jacket frame 2 and the connecting steel pipe 7;

[0051] The grouting cavity 309 is provided with a grouting hole 307 and an overflow hole 304 , and a fixing component is installed on the connecting steel pipe 7 .

[0052] To further optimize the solution, the upper jacket 2 includes several first supporting main legs 201, adjacent first supporting main legs 201 are fixed by first diagonal braces 202, pile platforms are fixed on the top ends of the first supporting main legs 201, and the tower frame 1 is fixed on the top surface of the pile platforms.

[0053] In the upper jacket 2, several first support legs 201 serve as the primary load-bearing components, carrying the vertical loads and horizontal wind and wave loads transmitted from the tower frame 1 via the pile base. The first diagonal braces 202 between adjacent first support legs 201 utilize the principle of triangular stabilization to distribute the load borne by a single first support leg 201 to adjacent legs, forming an integrated load-bearing system and reducing bending deformation of the legs. The pile base is fixed to the top of the first support leg 201. By expanding the load-bearing area, it evenly transfers the concentrated load of the tower frame 1 to each first support leg 201, avoiding excessive local stress. It also provides a stable installation foundation for the tower frame 1, ensuring its verticality and stability.

[0054] Further optimized, the lower jacket 3 includes a plurality of second supporting main legs 301, the first supporting main legs 201 and the second supporting main legs 301 are arranged in a one-to-one correspondence, the connecting steel pipe 7 is inserted into the second supporting main legs 301 through the guide device 310, and the adjacent second supporting main legs 301 are fixed by the second diagonal braces 302 and the horizontal braces 303, and the bottom of the second supporting main legs 301 is fixed on the steel pipe pile 4;

[0055] The second support legs 301 of the lower jacket 3 correspond one-to-one with the first support legs 201 of the upper jacket 2. Connecting steel pipes 7 ensure precise load transfer, transmitting the load from the upper jacket 2 via the second support legs 301 to the steel pipe piles 4 at the bottom, which then distribute it to the seabed foundation. Secondary diagonal braces 302 and horizontal braces 303 between adjacent secondary support legs 301 form a spatial grid structure. The secondary diagonal braces 302 primarily resist horizontal wind and wave loads and the structure's own lateral forces, while the horizontal braces 303 enhance the structure's horizontal rigidity, preventing lateral deflection or twisting of the secondary support legs 301. Together, these structures enhance the overall stability and deformation resistance of the lower jacket 3.

[0056] A further optimized solution is provided, in which the flange connection mechanism includes an upper flange 5 and a lower flange 6. The upper flange 5 is fixed to the bottom of the first supporting main leg 201, and the lower flange 6 is fixed to the top of the connecting steel pipe 7. A plurality of first bolt holes 501 are opened at equal intervals in the circumferential direction on the upper flange, and a plurality of second bolt holes 601 are opened at equal intervals in the circumferential direction on the lower flange 6. The first bolt holes 501 and the second bolt holes 601 are arranged in one-to-one correspondence, and a positioning bolt 311 is inserted between the first bolt hole 501 and the second bolt hole 601, and one end of the positioning bolt 311 is fixed by a nut.

[0057] The upper flange 5 and the lower flange 6 are respectively fixed to the bottom of the first supporting main leg 301 and the top of the connecting steel pipe 7, and are mechanically connected by means of positioning bolts 311 passing through the corresponding first and second bolt holes 601. The positioning bolts 311 generate axial force during the pre-tightening process, so that the upper and lower flanges fit tightly together, forming a rigid connection node that can withstand vertical pressure and tension, as well as transmit horizontal shear force and torque. The bolt 311 holes and positioning bolts 311 arranged at equal intervals around the circumference ensure uniform force, avoiding overload and fracture of local bolts 311. At the same time, they provide temporary fixation and precise positioning for the upper and lower conductor frames 3 before grouting, ensuring the coaxiality of the connecting steel pipe 7 and the supporting main leg, laying the foundation for subsequent grouting construction.

[0058] A further optimized solution is provided with two groups of fixing components, both of which are arranged on the connecting steel pipe 7 and located in the grouting cavity 309. The fixing components include guide limit blocks 305, and several groups of guide limit blocks 305 are fixed on the outer wall of the connecting steel pipe at equal intervals in the circumferential direction.

[0059] In the grouting cavity of the fixed assembly, the guide limit blocks 305 fixed at equal intervals along the outer wall of the connecting steel pipe 7 play a guiding role during the installation phase, ensuring that the connecting steel pipe 7 is accurately inserted into the second supporting main leg 301 to avoid excessive deviation;

[0060] According to a further optimized solution, the sealer includes a sealing ring 308 , which is fixed on the outer wall of the bottom end of the connecting steel pipe 7 .

[0061] After the connecting steel pipe 7 is inserted into the second support leg 301, the sealing ring 308 on the outer wall of the bottom end of the connecting steel pipe 7 tightly fits against the inner wall of the second support leg 301, forming a primary sealing barrier. This prevents leakage of grouting material within the grouting cavity 309 during grouting and curing. It also blocks impurities such as seawater and silt from entering the grouting cavity, thereby preventing the grouting material from curing and affecting the connection strength. The elastic deformation of the sealing ring 308 can accommodate the slight gap between the connecting steel pipe 7 and the support leg, ensuring a reliable seal.

[0062] As a further optimization solution, a plurality of groups of annular shear keys 306 are fixed to the outer wall of the connecting steel pipe 7 and the inner wall 3 of the lower conductor frame. The annular shear keys 306 are staggered and arranged at equal intervals along the axis of the connecting steel pipe.

[0063] To further optimize the solution, a guide device 310 is fixed to the bottom end of the connecting steel pipe 7 , and the guide device 310 is inserted into the second supporting main leg 301 .

[0064] During installation, the guide device 310 at the bottom of the connecting steel pipe 7 precisely guides the connecting steel pipe 7 into the second support leg 301. This tapered or cylindrical guide structure reduces insertion difficulty, ensures the connecting steel pipe 7 is coaxial with the second support leg 301, and reduces bumps and misalignment during installation. The guide device 310 also provides temporary support for the connecting steel pipe 7 during insertion, preventing it from tilting due to its own weight and ensuring positional accuracy during subsequent flange connection and grouting.

[0065] A flange and grouting combined connection method for a split-type jacket foundation structure of an offshore wind turbine comprises the following steps:

[0066] Step 1: Prefabrication of components in factory

[0067] During the factory processing phase, the connecting steel pipe 7 is placed within the lower jacket 3 via a guide device 310 and initially secured to the lower jacket 3 via a lower flange 6. Temporary supports or spot welding can be used to secure the relative position of the two. Once secured, the upper flange 5 at the bottom of the upper jacket 2 and the lower flange 6 at the top of the lower jacket 3 are pre-assembled in the factory, ensuring that the angles and positions meet design requirements. Finally, the sections are transported to the offshore construction platform.

[0068] Step 2: Install and fix the lower pipe frame 3 and the plug tip;

[0069] Fix the lower conductor frame 3 and its internal connecting steel pipe 7 to the seabed through the steel pipe piles 4 at the bottom. Use pile driving equipment to drive the steel pipe piles 4 into the seabed to a specified depth to ensure that the lower conductor frame 3 is firmly installed and accurately positioned, and its top is level as required by the design.

[0070] Step 3: hoisting the upper jacket 2 and preliminarily connecting the flanges;

[0071] Use large-scale lifting equipment to slowly lift the upper jacket 2 to the top of the lower jacket 3. During the lifting process, keep the upper jacket 2 stable, so that the bottom surface of the upper flange 5 and the top surface of the lower flange 6 are against each other, clean the debris and stains on the flange surface, ensure that the flange surface is flat and fits, and adjust the angle to pass the positioning bolt 311 through the bolt hole, and preliminarily tighten the bolt to achieve the initial connection and fixation of the upper and lower jackets 3;

[0072] Step 4: Grouting:

[0073] Check whether the grouting holes 307 and overflow holes 304 of the grouting cavity 309 are unobstructed and ensure that there is no blockage. According to the seawater environment and load-bearing requirements, select a slurry with good fluidity, seawater erosion resistance and high strength, and mix it according to the specified ratio. Slowly pour the slurry into the grouting cavity 309 through the grouting holes 307, controlling the pouring speed to avoid slurry segregation or bubble generation due to excessive speed, until the slurry evenly overflows from the overflow hole 304, indicating that the grouting cavity 309 is full. Close the grouting holes 307 and overflow hole 304, and cure the slurry in the grouting cavity 309 according to the slurry curing requirements.

[0074] Step 5: Final tightening of the flange connection mechanism;

[0075] After the grouting is completed, the bolts 311 of the flange connection mechanism are finally tightened; according to the prescribed tightening sequence and torque requirements, all bolts are tightened step by step and evenly to ensure that the flange connection is tight and the force is evenly distributed, so that the upper and lower jackets 3 are firmly connected through the flange connection mechanism;

[0076] Step 6: Quality inspection and acceptance;

[0077] Conduct a comprehensive quality inspection on the entire flange and grouting combined connection structure, including the tightness of the flange connection, whether the 311 torque of the bolt meets the requirements, the slurry fullness and strength of the grouting cavity meet the standards, and whether the fixed components are firmly installed; if any problems are found, make timely corrections until all inspection items meet the design and specification requirements.

[0078] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, 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 a limitation on the present invention.

[0079] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A split-type jacket foundation structure for an offshore wind turbine, characterized in that: include: A lower conductor frame (3), wherein a steel pipe pile (4) is fixed at the bottom of the lower conductor frame (3); An upper jacket (2), a tower frame (1) is installed on the top of the upper jacket (2), and the upper jacket (2) is installed on the top of the lower jacket (3); The plug tip comprises a connecting steel pipe (7) and a guide device (310), the connecting steel pipe (7) is entirely located inside the lower conductor frame (3), a lower flange (6) is provided on the top of the connecting steel pipe (7), and a sealer is provided on the bottom, and a grouting cavity (309) is formed between the top of the lower conductor frame (3) and the sealer; A flange connection mechanism, the flange connection mechanism being arranged at the bottom of the upper jacket (2) and the top of the connecting steel pipe (7), and being used to connect the upper jacket (2) and the connecting steel pipe (7); The grouting cavity (309) is provided with a grouting hole (307) and an overflow hole (304), and a fixing assembly is installed on the connecting steel pipe (7).

2. The offshore wind turbine split jacket foundation structure according to claim 1, characterized in that: The upper jacket (2) comprises a plurality of first supporting main legs (201), adjacent first supporting main legs (201) are fixed via first diagonal braces (202), a pile base is fixed at the top end of each first supporting main leg (201), and the tower frame (1) is fixed on the top surface of the pile base.

3. The offshore wind turbine split jacket foundation structure according to claim 2, characterized in that: The lower conductor frame (3) includes a plurality of second supporting main legs (301), wherein the first supporting main legs (201) and the second supporting main legs (301) are arranged in a one-to-one correspondence, and the connecting steel pipe 7 is inserted into the second supporting main legs through a guide device 310, and adjacent second supporting main legs (301) are fixed by second diagonal braces (302) and horizontal braces (303), and the bottom of the second supporting main legs (301) is fixed on the steel pipe pile (4).

4. The offshore wind turbine split jacket foundation structure according to claim 3, characterized in that: The flange connection mechanism includes an upper flange (5) and a lower flange (6), wherein the upper flange (5) is fixed to the bottom of the first supporting main leg (201), and the lower flange (6) is fixed to the top of the connecting steel pipe (7). A plurality of first bolt holes (501) are provided at equal intervals in the circumferential direction on the upper flange (5), and a plurality of second bolt holes (601) are provided at equal intervals in the circumferential direction on the lower flange (6). The first bolt holes (501) and the second bolt holes (601) are arranged in a one-to-one correspondence, and a positioning bolt (311) is inserted between the first bolt hole (501) and the second bolt hole (601), and one end of the positioning bolt (311) is fixed by a nut.

5. The offshore wind turbine split jacket foundation structure according to claim 3, characterized in that: The fixing assembly is arranged on the connecting steel pipe (7) and is located in the grouting cavity (309). The fixing assembly includes a guide limit block (305). A plurality of guide limit blocks (305) are fixed at equal intervals on the outer wall of the connecting steel pipe (7).

6. The offshore wind turbine split jacket foundation structure according to claim 1, characterized in that: The sealer comprises a sealing ring (308), and the sealing ring (308) is fixed on the outer wall of the bottom end of the connecting steel pipe (7).

7. The offshore wind turbine split jacket foundation structure according to claim 1, characterized in that: A plurality of groups of annular shear keys (306) are fixed to the outer wall of the connecting steel pipe (7) and the inner wall of the lower conductor frame (3), and the annular shear keys (306) are staggered and arranged at equal intervals along the axis of the connecting steel pipe (7).

8. The offshore wind turbine split jacket foundation structure according to claim 3, characterized in that: The guide device (310) is inserted into the second supporting main leg (301).

9. A flange and grouting combined connection method for an offshore wind turbine split jacket foundation structure, based on the offshore wind turbine split jacket foundation structure according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: Prefabrication of each component in the factory; During the factory processing stage, the connecting steel pipe is placed in the lower jacket through a guide device and initially fixed in the lower jacket via the lower flange. Temporary support or spot welding can be used to fix the relative position of the two. After the fixation is completed, the upper flange at the bottom of the upper jacket and the lower flange at the top of the lower jacket are pre-joined in the factory to ensure that the angle and position meet the design requirements. Finally, the pipe is transported to the offshore construction platform in sections. Step 2: The lower conductor frame (3) and the plug tip are installed and fixed; the lower conductor frame (3) and the connecting steel pipe (7) inside it are fixed on the seabed through the steel pipe pile (4) at the bottom thereof, and the steel pipe pile (4) is driven into the seabed to a specified depth using a pile driving device to ensure that the lower conductor frame (3) is firmly installed and accurately positioned, and the horizontality of its top meets the design requirements; Step 3: hoisting the upper jacket (2) and performing preliminary flange connection; Use large-scale lifting equipment to slowly lift the upper conductor frame (2) to the top of the lower conductor frame (3). During the lifting process, keep the upper conductor frame (2) stable, so that the bottom surface of the upper flange (5) and the top surface of the lower flange (6) are aligned, clean the debris and stains on the flange surface, ensure that the flange surface is flat and fits, and adjust the angle to pass the positioning bolt (311) through the bolt hole, preliminarily tighten the bolt, and achieve the initial connection and fixation of the upper and lower conductor frames (3); Step 4: Grouting: Check whether the grouting hole (307) and the overflow hole (304) of the grouting cavity (309) are unobstructed to ensure that there is no blockage; select a slurry with good fluidity, seawater erosion resistance and high strength according to the seawater environment and load-bearing requirements, and mix it according to the specified ratio; slowly pour the slurry into the first grouting cavity (309) through the grouting hole (307), control the pouring speed to avoid slurry segregation or bubble generation due to excessive speed, until the slurry overflows evenly from the overflow hole (304), indicating that the grouting cavity (309) is filled, close the grouting hole (307) and the overflow hole (304), and maintain the slurry in the first grouting cavity (309) according to the slurry maintenance requirements; Step 5: Final tightening of the flange connection mechanism; After the grouting is completed, the bolts (311) of the flange connection mechanism are finally tightened; all the bolts (311) are tightened step by step and evenly according to the prescribed tightening sequence and torque requirements to ensure that the flange connection is tight and the force is evenly applied, so that the upper and lower jackets (3) are firmly connected through the flange connection mechanism; Step 6: Quality inspection and acceptance; Conduct a comprehensive quality inspection of the entire flange and grouting combined connection structure, including whether the tightness of the flange connection, whether the torque of the bolts (311) meets the requirements, whether the grouting cavity slurry is full and strong enough, and whether the fixing components are firmly installed; If any problems are found, timely rectification shall be carried out until all inspection items meet the design and specification requirements.

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