Suction group anchor and gravity combined foundation and construction method thereof

Abstract

This invention discloses a combined suction anchor and gravity foundation and its construction method, belonging to the field of marine engineering technology. It solves the problem of difficult anchoring of gravity foundations in deep-water, high-load, and complex hard-layered soil environments. The foundation includes a gravity cap structure, a suction anchor system, and a rigid load-transfer layer. The suction anchor system is fixed to the underwater foundation, and the top of the suction anchor system is supported by the rigid load-transfer layer. The top of the rigid load-transfer layer is mechanically connected to the gravity cap structure. The gravity cap structure is internally divided into a core load-bearing zone and an edge adjustment zone, both filled with ballast material. In this invention, precise guidance and initial locking are achieved through the interlocking of male and female shear key arrays on the rigid load-transfer layer and the mechanical connection of the edge anchors. Subsequently, a grouting process is used to fill the gaps in the mechanical processing, achieving dual protection through mechanical means and grouting, significantly improving connection stiffness and overall reliability.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, and in particular to a combined suction anchor and gravity foundation and its construction method. Background Technology

[0002] As offshore wind power and other marine engineering projects continue to expand into deeper waters, the marine hydrological and seabed geological conditions faced by the foundation structures are becoming increasingly complex. Offshore wind power foundation structures are mainly divided into two categories based on water depth, geological conditions, and environmental factors: fixed foundations and floating foundations. Fixed foundations mainly include monopile foundations, jacket foundations, gravity foundations, and suction bucket foundations. Among these, monopile foundations are simple in structure and convenient to construct, making them the most widely used foundation type. Jacket foundations have high rigidity and stability, capable of resisting large horizontal forces and bending moments. Gravity foundations rely on their own weight to resist the overturning moment generated by the wind turbine; during construction, a gravity structure is formed by pouring concrete or installing prefabricated components to ensure the stability of the foundation. Suction bucket foundations utilize the principle of suction to press a cylindrical structure into the seabed, suitable for medium water depths and soft soil foundations. Floating foundations are suitable for deep water areas, using mooring systems to fix the wind turbine in a designated location. Floating foundations include various types such as semi-submersible, tension leg, and monopile foundations, capable of adapting to the complex environmental conditions of deep water areas.

[0003] In fixed foundations, traditional single gravity foundations require an extremely large volume and weight in deep water areas, resulting in high manufacturing costs and extremely high requirements for ship-mounted lifting capabilities. Meanwhile, single suction bucket foundations, when encountering hard seabed soil layers (such as dense sand), are prone to "soil plug" heave and failure due to relying solely on internal negative pressure, leading to penetration difficulties or even failure. To solve the anchoring challenges of deep-water, high-load, and complex hard-layer foundations, there is an urgent need to develop a new composite foundation structure and construction technology that can comprehensively utilize the advantages of gravity's compressive strength and suction's pull-out strength, adapt to different levels of lifting ship-mounted capabilities, and flexibly adjust the penetration strategy when encountering hard soil layers. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a combined suction anchor and gravity foundation and its construction method, which solves the problem of difficulty in anchoring gravity foundations in deep water with large loads and complex hard interlayer foundation environments.

[0005] Firstly, in order to achieve the above objectives, the technical solution adopted by the present invention is as follows: A combined suction anchor and gravity foundation includes a gravity pier structure, a suction anchor system, and a rigid load-transfer layer. The suction anchor system is fixed to the underwater foundation, and the top of the suction anchor system is supported by the rigid load-transfer layer. The top of the rigid load-transfer layer is mechanically connected to the gravity pier structure. The rigid load-transfer layer is used to transfer the load of the gravity pier structure to the suction anchor system. The gravity pier structure is internally divided into a core load-bearing zone and an edge adjustment zone. Both the core load-bearing zone and the edge adjustment zone are filled with ballast material through filling ports.

[0006] In this design, a rigid load-bearing layer is positioned between the gravity-supported pier structure and the suction anchor system. As a core mechanical connecting component, it integrates the gravity-supported pier structure and the suction anchor system into a unified whole, enabling load transfer and jointly resisting the loads of the complex marine environment. The core stabilization zone and the edge adjustment zone possess dual functions of overall balance and leveling, achieving attitude leveling by filling with ballast material.

[0007] Furthermore, the core load-bearing area is located in the middle of the box, and the edge adjustment area is distributed around the core load-bearing area; the core load-bearing area is used to provide ballast to maintain the overall balance of the foundation, and the edge adjustment area is used to adjust the attitude of the foundation by filling ballast material with differential filling or water injection.

[0008] In this scheme, the core fixed load area and the edge adjustment area have the dual functions of overall balance and leveling. The core fixed load area, due to its central location and large volume, mainly focuses on providing permanent gravity anti-overturning moment to maintain the overall balance of the foundation. The edge adjustment area, distributed around the perimeter, has a large lever arm advantage and mainly focuses on leveling the foundation by differentially filling ballast material or temporarily injecting and draining water into the compartments in different orientations.

[0009] Furthermore, the gravity-type pier structure is a square box structure, with several anchor rope mooring points and several filling ports on the top surface of the box structure.

[0010] In this design, anchor points are arranged on the top surface of the box structure for connection to the upper floating platform or mooring system. Heavy-duty ballast materials such as mineral sands can be filled into the core fixed-load area and the edge adjustment area through the filling port to achieve attitude leveling.

[0011] Furthermore, the gravity-type foundation structure and the rigid load-bearing layer are mechanically connected by bolts and an array of shear keys.

[0012] Furthermore, the bottom surface of the gravity-type foundation structure is uniformly arranged with several downward-protruding shear key array male heads, and the upper surface of the rigid force transmission layer is provided with shear key array female heads corresponding to the shear key array male heads. The shear key array male heads are embedded in the shear key array female heads to withstand horizontal shear forces. Flange edges are provided around both the gravity-type foundation structure and the rigid force transmission layer, and several bolt holes are provided on the flange edges. The gravity-type foundation structure and the rigid force transmission layer are connected by bolts that pass through the bolt holes. After being connected by anchor bolts, grouting is performed at the connection interface between the gravity-type foundation structure and the rigid force transmission layer to ensure that the shear key array male heads and shear key array female heads are tightly overlapped, and the upper and lower structures are solidified into a whole.

[0013] In this scheme, when the gravity-type pier structure is placed above the rigid force transmission layer, the male shear key array head is fully inserted into the female shear key array head, thereby achieving extremely strong resistance to horizontal shearing. At the same time, since the male shear key array head is designed with a tapered structure, it can also play a guiding and limiting role during docking and installation.

[0014] Furthermore, the rigid force transmission layer is a plate-shaped steel structure component, and each of the four sides of the plate-shaped steel structure component is hinged with an anti-erosion skirt; the anti-erosion skirt is flipped outward and laid flat against the seabed surface.

[0015] In this design, after the foundation is fully inserted into the seabed, the anti-scour skirt is opened using an external device, allowing it to flip outwards and unfold to lie flat against the seabed surface, thus preventing the bottom currents from scouring and eroding the foundation.

[0016] Furthermore, the bottom surface of the rigid force transmission layer is provided with several suction anchor connections; the suction anchor system consists of several suction anchor barrels, and the top cover of each suction anchor barrel is rigidly connected to the corresponding suction anchor connection; the top surface of the suction anchor barrel is provided with radially arranged reinforcing ribs and drainage holes for pumping water.

[0017] Secondly, based on the suction anchor group and gravity combined foundation provided in the first aspect, the present invention provides a construction method for a suction anchor group and gravity combined foundation, which adopts an integral prefabrication and assembly construction method, including the following steps: Step A1: Prefabricate and assemble on land; manufacture gravity-type pier structure, suction anchor system and rigid force transmission layer, and complete the rigid connection of suction anchor system and rigid force transmission layer on land by fitting shear key array and locking bolts. Then, perform grouting on the periphery of the interface to make suction anchor system and rigid force transmission layer form a whole. Step A2: Self-floating transport and coordinated penetration; using the buoyancy of the cavity of the gravity-type foundation structure and the air chamber of the suction anchor barrel to transport the pre-assembled foundation to the machine position; through water injection into the edge adjustment area and negative pressure coordinated penetration of the suction anchor system, and using differential negative pressure for overall leveling; Step A3: Perform overall balancing and attitude leveling; fill the core load area and edge adjustment area with ballast material to complete the fine leveling and final overall balancing of the foundation, and complete the foundation construction.

[0018] Furthermore, during the penetration process in step A2, a resistance-matching dynamic penetration technique is adopted. The specific construction steps include: Step A201: Lower the pre-assembled foundation to the seabed, open the pumping holes of the suction anchor system to initiate normal negative pressure penetration mode, and simultaneously monitor the penetration resistance R in real time using the equipped pressure and displacement sensors. i ; Step A202: Determine whether the resistance gradient exceeds the set threshold, i.e., determine whether a hard layer has been encountered, causing penetration resistance R. i If the increase is sudden but does not exceed the set threshold, the normal negative pressure penetration mode will continue; if it exceeds the threshold, proceed to step A203. Step A203: Trigger the resistance matching program, pause the suction pump, and lock the negative pressure inside the suction anchor barrel; Step A204: Open the filling port of the edge adjustment zone of the gravity-type foundation structure and inject water into the edge adjustment zone; Step A205: Utilize the increased weight from water injection to generate additional downward pressure, perform gravity-assisted soil breaking, and force the suction anchor to cut into the hard layer; Step A206: Determine in real time whether the hard soil layer has been penetrated. If not, continue with the gravity-assisted soil breaking in step A205. If the hard soil layer has been penetrated, return to step A201 and restore the normal negative pressure settlement mode until the foundation settles to the design elevation.

[0019] Thirdly, based on the suction anchor group and gravity combined foundation provided in the first aspect, this invention provides a construction method for a suction anchor group and gravity combined foundation, employing a split installation method, including the following steps: Step B1: Prefabrication and transportation of separate components; manufacture the suction anchor system, gravity pier structure and rigid load-bearing layer separately, and transport them to the construction sea area; Step B2: Group anchor positioning and individual sinking; using the seabed positioning frame, sink each suction anchor barrel to the design depth in sequence according to the set array coordinates, and level the top surface of each anchor barrel. Step B3: Foundation alignment and lowering; hoist and lower the superstructure so that the male shear key array at the bottom of the gravity foundation structure is aligned and engaged with the female shear key array on the rigid load transfer layer. Step B4: Mechanical locking, interface grouting and ballast conversion; After underwater alignment and locking are completed, the anchor bolts at the edges are tightened by underwater operation, and then the outer interface grouting is carried out between the gravity pier structure and the rigid force transmission layer to make the gap of the shear key array completely dense, and the suction anchor system and the rigid force transmission layer are consolidated into a whole. Step B5: Perform overall balancing and attitude leveling; fill the core load area and edge adjustment area with ballast material to complete the fine leveling and final overall balancing of the foundation, and complete the foundation construction.

[0020] The beneficial effects of this invention are: The present invention achieves precise guidance and initial locking through the interlocking of male and female shear key arrays on the rigid force transmission layer and the mechanical connection of edge anchors. Subsequently, in conjunction with the grouting process of the outer interface, the gaps in the mechanical processing are perfectly filled, so that the shear keys are densely overlapped. This provides dual protection through mechanical and grouting, ensuring that the upper and lower structures of the gravity support and suction anchor group are completely integrated into an absolutely rigid whole, which greatly improves the connection stiffness and overall reliability.

[0021] This invention features a core load-bearing zone and an edge adjustment zone, both of which can be filled with heavy-duty materials such as minerals. The edge zone utilizes its large span lever arm for high-precision attitude leveling, while the core zone provides a high-weight foundation to maintain overall balance. The functions of the two zones are mutually integrated and complementary, achieving optimal control of the center of gravity.

[0022] This invention designs a dual-mode installation process that supports both overall self-floating installation and modular assembly. Combined with the unique mechanical guidance docking function of the structure, it achieves flexible adaptation to different levels of ship machinery and equipment and different sea state windows.

[0023] This invention employs a "resistance matching" construction method, cleverly utilizing the edge adjustment zone around the foundation. When encountering hard soil layers, water injection to increase weight replaces simple negative pressure suction, effectively preventing damage to the soil plug inside the suction barrel and greatly improving the penetration success rate in complex strata.

[0024] This invention features a rigid force transmission layer with hinged anti-scour skirts around its perimeter. These skirts remain closed during the penetration process, preventing water resistance interference and component damage during lowering. After the foundation is in place, the skirts are precisely opened using external devices (such as ROVs or release cables) to conform to the seabed topography. This reduces the weakening of the foundation's bearing capacity caused by seawater scouring and lowers subsequent maintenance costs. Attached Figure Description

[0025] Figure 1 This is a schematic cross-sectional view of the overall structure of the combined suction anchor and gravity foundation of the present invention.

[0026] Figure 2This is a three-dimensional schematic diagram of the overall structure of a combined suction anchor and gravity foundation according to the present invention.

[0027] Figure 3 This is a schematic cross-sectional view of the gravity-type foundation structure in this invention.

[0028] Figure 4 This is a three-dimensional schematic diagram of the gravity-type foundation structure in this invention.

[0029] Figure 5 This is a plan view of the gravity-type foundation structure in this invention.

[0030] Figure 6 This is a three-dimensional schematic diagram of the rigid force transmission layer in this invention.

[0031] Figure 7 This is a cross-sectional schematic diagram of the rigid force transmission layer in this invention.

[0032] Figure 8 This is a top view of the bottom surface of the rigid force transmission layer in this invention.

[0033] Figure 9 This is a three-dimensional schematic diagram of the suction group anchor in this invention.

[0034] Figure label: 1. Gravity-type foundation structure; 11. Core fixed load area; 12. Edge adjustment area; 13. Anchor rope mooring point; 14. Filling port; 2. Suction anchor system; 21. Reinforcing rib beam; 22. Pumping hole; 3. Rigid force transmission layer; 31. Shear key array; 311. Male shear key array head; 312. Female shear key array head; 32. Bolt hole; 33. Suction anchor connection; 4. Anti-erosion skirt; Detailed Implementation The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Specific embodiments of the present invention are described below to facilitate understanding by those skilled in the art. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0035] Example 1 like Figures 1-2 As shown, this embodiment provides a combined suction anchor and gravity foundation, which solves the problem of difficult anchoring of gravity foundations in deep water with large loads and complex hard interlayer foundation environments; specifically, it includes: 1. Gravity-type foundation structure; 2. Suction anchor system; 3. Rigid force transmission layer; 4. Anti-erosion skirt; Among them, the suction anchor system 2 is fixed on the underwater foundation. The top of the suction anchor system 2 is supported by a rigid force transmission layer 3. The top of the rigid force transmission layer 3 is connected to the gravity support structure 1 through a mechanical structure. The rigid force transmission layer 3 serves as the core mechanical connection component that connects the upper and lower parts. It is used to transfer the load of the gravity support structure 1 to the suction anchor system 2, so as to jointly resist the load of the complex marine environment.

[0036] like Figures 3-5 As shown, the gravity-type foundation structure 1 is internally divided into a core ballast zone 11 and an edge adjustment zone 12. Both the core ballast zone 11 and the edge adjustment zone 12 are filled with heavy-duty ballast materials such as mineral sand through filling ports 14. The core ballast zone 11 is located in the middle of the box, and the edge adjustment zone 12 is distributed around the core ballast zone 11. The core ballast zone 11 is used to provide ballast to maintain the overall balance of the foundation, while the edge adjustment zone 12 is used to perform attitude leveling of the foundation by differentially filling ballast materials or injecting water. The core ballast zone 11 and the edge adjustment zone 12 have the dual functions of overall balance and leveling. The core ballast zone 11, due to its central location and large volume, mainly focuses on providing permanent gravity anti-overturning moment to maintain the overall balance of the foundation. The edge adjustment zone 12, distributed around the perimeter, has a large lever arm advantage and mainly focuses on performing attitude leveling of the foundation by differentially filling ballast materials in compartments in different orientations or temporarily injecting and draining water.

[0037] The gravity-type support structure 1 is a square box structure. The top surface of the box structure is provided with several anchor rope mooring points 13 and several filling ports 14. The anchor rope mooring points 13 are used to connect with the upper floating platform or mooring system; the filling ports 14 can be used to fill the core fixed load area 11 and the edge adjustment area 12 with heavy-duty ballast materials such as mineral sand to achieve the effect of attitude leveling.

[0038] The gravity-type foundation structure 1 and the rigid force transmission layer 3 are mechanically connected by bolts and shear key array 31.

[0039] like Figure 4 As shown, the bottom surface of the gravity-type foundation structure 1 has a plurality of downwardly protruding shear key array males 311 evenly arranged; as Figure 6 As shown, the upper surface of the rigid force transmission layer 3 is provided with a shear key array female head 312 corresponding to the shear key array male head 311. When the gravity-type support structure 1 is placed above the rigid force transmission layer 3, the shear key array male head 311 is fully inserted into the shear key array female head 312, thereby achieving extremely strong resistance to horizontal shearing. At the same time, since the shear key array male head 311 is designed with a conical structure, it can also play a guiding and limiting role during docking and installation.

[0040] like Figures 6-7As shown, both the gravity-type foundation structure 1 and the rigid force-transfer layer 3 are surrounded by flanges, with several bolt holes 32 on the flanges. The gravity-type foundation structure 1 and the rigid force-transfer layer 3 are connected by bolts passing through the bolt holes 32. After the connection is made by anchor bolts, grouting is performed at the interface between the gravity-type foundation structure 1 and the rigid force-transfer layer 3 to ensure that the male head 311 and the female head 312 of the shear key array are tightly overlapped, and the upper and lower structures are solidified into a whole.

[0041] like Figure 8 As shown, the rigid force transmission layer 3 is a plate-shaped steel structure component, and anti-scour skirts 4 are hinged to the four sides of the plate-shaped steel structure component. After the foundation is inserted into the seabed and positioned, the anti-scour skirts 4 are opened using an external device, so that they are flipped outward and laid flat against the seabed surface to prevent the bottom current from scouring and eroding the bottom of the foundation.

[0042] The bottom surface of the rigid force transmission layer 3 has four suction anchor connection points 33; the suction anchor system 2 consists of four suction anchor barrels arranged in a square; the top cover of each suction anchor barrel is rigidly connected to the corresponding suction anchor connection point 33. Figure 9 As shown, the top surface of the suction anchor barrel is provided with radially arranged reinforcing ribs 21 and a water pumping hole 22 for pumping out water.

[0043] Example 2 This embodiment, based on the suction anchor group and gravity combined foundation provided in Embodiment 1, provides a construction method for the suction anchor group and gravity combined foundation, which adopts an integral prefabrication and assembly construction method, including the following steps: Step A1: Prefabricate and assemble on land; manufacture gravity-type pier structure 1, suction anchor system 2 and rigid force transmission layer 3, and complete the rigid connection of suction anchor system 2 and rigid force transmission layer 3 on land by fitting shear key array 31 and locking bolts. Then, perform grouting on the periphery of the interface to make suction anchor system 2 and rigid force transmission layer 3 form a whole.

[0044] Step A2: Self-floating transport and coordinated penetration; utilizing the buoyancy of the cavity of the gravity-type foundation structure 1 and the air chamber of the suction anchor barrel, the pre-assembled foundation is transported to the machine position; through water injection into the edge adjustment zone 12 and the negative pressure of the suction anchor system 2, coordinated penetration is achieved, and overall leveling is performed using differential negative pressure; specifically including: Step A201: Lower the pre-assembled foundation to the seabed, open the pumping port 22 of the suction anchor system 2 to initiate normal negative pressure penetration mode, and simultaneously monitor the penetration resistance R in real time using the equipped pressure and displacement sensors. i ; Step A202: Determine whether the resistance gradient exceeds the set threshold, i.e., determine whether a hard layer has been encountered, causing penetration resistance R. iIf the increase is sudden but does not exceed the set threshold, the normal negative pressure penetration mode will continue; if it exceeds the threshold, proceed to step A203. Step A203: Trigger the resistance matching program, pause the suction pump, and lock the negative pressure inside the suction anchor barrel; Step A204: Open the filling port 14 of the edge adjustment area 12 of the gravity-type foundation structure 1 and inject water into the edge adjustment area 12; Step A205: Utilize the increased weight from water injection to generate additional downward pressure, perform gravity-assisted soil breaking, and force the suction anchor to cut into the hard layer; Step A206: Determine in real time whether the hard soil layer has been penetrated. If not, continue with the gravity-assisted soil breaking in step A205. If the hard soil layer has been penetrated, return to step A201 and restore the normal negative pressure settlement mode until the foundation settles to the design elevation.

[0045] Step A3: Perform overall balancing and attitude leveling; fill the core fixed load area 11 and the edge adjustment area 12 with high-density solid ballast materials such as heavy-duty mineral sand to complete the fine leveling and final overall balancing of the foundation, and complete the foundation construction.

[0046] Example 3 This embodiment, based on the suction anchor group and gravity combined foundation provided in Embodiment 1, provides a construction method for the suction anchor group and gravity combined foundation, which adopts a split installation construction method and includes the following steps: Step B1: Prefabrication and transportation of separate components; manufacture the suction anchor system 2, gravity pier structure 1 and rigid force transmission layer 3 separately, and transport them to the construction sea area; Step B2: Group anchor positioning and individual sinking; using the seabed positioning frame, sink each suction anchor barrel to the design depth in sequence according to the set array coordinates, and level the top surface of each anchor barrel. Step B3: Foundation alignment and lowering; hoist and lower the superstructure so that the male shear key array 311 at the bottom of the gravity foundation structure 1 is aligned and engaged with the female shear key array 312 on the rigid force transmission layer 3. Step B4: Mechanical locking, interface grouting and ballast conversion; After underwater alignment and locking are completed, the anchor bolts at the edge are tightened by underwater operation, and then the outer interface grouting is carried out between the gravity-type pier structure 1 and the rigid force transmission layer 3 to make the gap of the shear key array 31 completely dense, and the suction group anchor system 2 and the rigid force transmission layer 3 are consolidated into a whole. Step B5: Perform overall balancing and attitude leveling; fill the core fixed load area 11 and the edge adjustment area 12 with high-density solid ballast materials such as heavy-duty mineral sand to complete the fine leveling and final overall balancing of the foundation, and complete the foundation construction.

[0047] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention and should be understood as not limiting the scope of protection of the invention to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed herein without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the invention.

Claims

1. A combined suction anchor and gravity foundation, characterized in that: It includes a gravity-type pier structure (1), a suction anchor system (2), and a rigid force transmission layer (3); the suction anchor system (2) is fixed on the underwater foundation, and the top of the suction anchor system (2) is supported by the rigid force transmission layer (3), and the top of the rigid force transmission layer (3) is connected to the gravity-type pier structure (1) through a mechanical structure; the rigid force transmission layer (3) is used to transfer the load of the gravity-type pier structure (1) to the suction anchor system (2); the gravity-type pier structure (1) is divided into a core fixed load area (11) and an edge adjustment area (12); both the core fixed load area (11) and the edge adjustment area (12) are filled with ballast material through filling ports (14).

2. The combined suction anchor and gravity foundation according to claim 1, characterized in that: The core load-bearing area (11) is located in the middle of the box body, and the edge adjustment area (12) is distributed around the core load-bearing area (11); wherein, the core load-bearing area (11) is used to provide ballast to maintain the overall balance of the foundation, and the edge adjustment area (12) is used to adjust the posture of the foundation by differentially filling ballast material or injecting water.

3. The combined suction anchor and gravity foundation according to claim 2, characterized in that: The gravity-type support structure (1) is a square box structure, and the top surface of the box structure is provided with several anchor rope mooring points (13) and several filling ports (14).

4. The combined suction anchor and gravity foundation according to claim 1, characterized in that: The gravity-type pier structure (1) and the rigid force transmission layer (3) are mechanically connected by bolts and shear key array (31).

5. The combined suction anchor and gravity foundation according to claim 4, characterized in that: The bottom surface of the gravity-type pier structure (1) is uniformly arranged with several downwardly protruding shear key array male heads (311). The upper surface of the rigid force transmission layer (3) is provided with shear key array female heads (312) corresponding to the shear key array male heads (311). The shear key array male heads (311) are embedded in the shear key array female heads (312) to withstand horizontal shear forces. Flange edges are provided around the gravity-type pier structure (1) and the rigid force transmission layer (3). Several bolt holes (32) are provided on the flange edges. The gravity-type pier structure (1) and the rigid force transmission layer (3) are connected by bolts that pass through the bolt holes. After being connected by anchor bolts, grouting is performed at the connection interface between the gravity-type pier structure (1) and the rigid force transmission layer (3) so that the shear key array male heads (311) and the shear key array female heads (312) are tightly overlapped, and the upper and lower structures are solidified into a whole.

6. The combined suction anchor and gravity foundation according to claim 1, characterized in that: The rigid force transmission layer (3) is a plate-shaped steel structure component, and the four sides of the plate-shaped steel structure component are all hinged with anti-erosion skirts (4); the anti-erosion skirts (4) are flipped outward and laid flat on the seabed surface.

7. The combined suction anchor and gravity foundation according to claim 1, characterized in that: The bottom surface of the rigid force transmission layer (3) is provided with several suction group anchor connection points (33); the suction group anchor system (2) is composed of several suction anchor barrels, and the top cover of each suction anchor barrel is rigidly connected to the corresponding suction group anchor connection point (33); the top surface of the suction anchor barrel is provided with radially arranged reinforcing ribs (21) and a water pumping hole (22) for pumping out water.

8. A construction method for a combined suction anchor and gravity foundation according to any one of claims 1-7, characterized in that, The construction method using integrated prefabrication and assembly includes the following steps: Step A1: Prefabrication and assembly on land; manufacture gravity-type pier structure (1), suction anchor system (2) and rigid force transmission layer (3), and complete the rigid connection of suction anchor system (2) and rigid force transmission layer (3) on land by fitting shear key array (31) and locking bolts. Then, perform grouting on the periphery of the interface to make suction anchor system (2) and rigid force transmission layer (3) form a whole. Step A2: Self-floating transport and coordinated penetration; using the buoyancy of the cavity of the gravity-type foundation structure (1) and the air chamber of the suction anchor barrel to transport the pre-assembled foundation to the machine position; through water injection into the edge adjustment area (12) and the negative pressure of the suction anchor system (2) to coordinate sinking, and using differential negative pressure for overall leveling; Step A3: Perform overall balancing and attitude leveling; fill the core fixed load area (11) and edge adjustment area (12) with ballast material to complete the fine leveling and final overall balancing of the foundation and complete the foundation construction.

9. The construction method of the combined suction anchor and gravity foundation according to claim 8, characterized in that: During the penetration process in step A2, a resistance-matching dynamic penetration technique is adopted. The specific construction steps include: Step A201: Lower the pre-assembled foundation to the seabed and open the pumping holes (22) of the suction anchor system (2) to perform normal negative pressure penetration mode. At the same time, the penetration resistance R is monitored in real time by the equipped pressure sensor and displacement sensor. i ; Step A202: Determine whether the resistance gradient exceeds the set threshold, i.e., determine whether a hard layer has been encountered, causing penetration resistance R. i If the increase is sudden but does not exceed the set threshold, the normal negative pressure penetration mode will continue; if it exceeds the threshold, proceed to step A203. Step A203: Trigger the resistance matching program, pause the suction pump, and lock the negative pressure inside the suction anchor barrel; Step A204: Open the filling port (14) of the edge adjustment area (12) of the gravity-type foundation structure (1) and inject water into the edge adjustment area (12); Step A205: Utilize the increased weight from water injection to generate additional downward pressure, perform gravity-assisted soil breaking, and force the suction anchor to cut into the hard layer; Step A206: Determine in real time whether the hard soil layer has been penetrated. If not, continue with the gravity-assisted soil breaking in step A205. If the hard soil layer has been penetrated, return to step A201 and restore the normal negative pressure settlement mode until the foundation settles to the design elevation.

10. A construction method for a combined suction anchor and gravity foundation according to any one of claims 1-7, characterized in that, The construction method using a split-type installation includes the following steps: Step B1: Prefabrication and transportation of separate components; manufacture the suction anchor system (2), gravity pier structure (1) and rigid load transfer layer (3) separately, and transport them to the construction sea area; Step B2: Group anchor positioning and individual sinking; using the seabed positioning frame, sink each suction anchor barrel to the design depth in sequence according to the set array coordinates, and level the top surface of each anchor barrel. Step B3: Foundation alignment and lowering; hoist the upper structure down so that the male shear key array (311) at the bottom of the gravity foundation structure (1) is aligned and engaged with the female shear key array (312) on the rigid force transmission layer (3); Step B4: Mechanical locking, interface grouting and ballast conversion; After underwater alignment and locking are completed, the anchor bolts on the edge are tightened by underwater operation, and then the outer interface grouting is carried out between the gravity pier structure (1) and the rigid force transmission layer (3) to make the gap of the shear key array completely dense, and the suction group anchor system (2) and the rigid force transmission layer (3) are solidified into a whole; Step B5: Perform overall balancing and attitude leveling; fill the core fixed load area (11) and edge adjustment area (12) with ballast material to complete the fine leveling and final overall balancing of the foundation, and complete the foundation construction.

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