Tension leg-screw pile anchoring system suitable for floating offshore platform

Abstract

The utility model provides a tension leg-screw pile anchoring system suitable for a floating offshore platform. The tension leg-screw pile anchoring system is composed of a floating platform, tension legs and screw piles. Wherein the floating platform comprises a top plate, a supporting column, a transverse floating box and a vertical floating cylinder; each tension leg comprises a connecting key, a tension rib, a connector and a connecting steel cable; the spiral pile comprises a bottomless steel pipe pile and a spiral disc. The floating platform is connected with the floating fan equipment at the upper part through a central column, and is connected with the tension legs at the lower part through connecting keys; the lower portions of the tension legs are connected with the spiral piles through connecting pieces and connecting steel cables. The floating platform provides buoyancy for upper equipment of the top plate, and the supporting columns reduce stress of the platform under the action of sea surface waves through the small waterline area of the supporting columns. The tension leg mooring system is used for limiting the motion response of the floating platform and has large vertical and horizontal rigidity. The screw pile is anchored on the seabed and bears the tension force transmitted from the tension rib. The scheme is suitable for offshore floating structures in sea areas with large water level changes.

Description

Technical Field

[0001] The utility model belongs to the technical field of offshore floating platforms, and particularly relates to a tension leg - screw pile mooring system applicable to floating offshore platforms. Background Art

[0002] For the construction of offshore equipment such as floating photovoltaic and floating ocean ranch, a reasonable selection of the anchoring foundation form can reduce the construction cost. Most of the existing offshore floating body mooring systems adopt pile anchors, plate anchors or suction anchors. The cost, transportation and installation construction difficulty of pile anchors are very high, and they will increase significantly with the increase of water depth. Although the cost of plate anchors is relatively low, their installation requires complex processes such as towing and rotational adjustment, and they have high requirements for construction space and construction conditions. The installation of suction anchors is relatively simple, but judging from the feedback in the oil and gas industry, its later maintenance difficulty and cost are relatively high, and there are also doubts about its durability and reliability. Summary of the Invention

[0003] In order to overcome the above - mentioned disadvantages of the prior art, the purpose of the utility model is to provide a tension leg - screw pile mooring system applicable to floating offshore platforms, which can improve the stability of floating platforms in sea areas with large water level changes and strong wave force effects, optimize the space utilization rate of the mooring system, enhance the bearing capacity of the anchoring system, and reduce the overall cost.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0005] A tension leg - screw pile mooring system applicable to floating offshore platforms, comprising a floating platform, a tension leg and a screw pile;

[0006] The floating platform floats on the sea surface, is used to carry equipment and provide buoyancy for the equipment. Its lower part is connected to the top end of the tension leg, the bottom end of the tension leg is connected to the top end of the screw pile, and the screw pile is anchored to the seabed, with a part of the upper part reserved for connection with the tension leg; the screw pile provides tension for fixing the bottom end of the tension leg, and the tension leg provides tension for restricting the horizontal and vertical movements of the floating platform.

[0007] In one embodiment, the floating platform includes a top plate, four support columns, four vertical floating cylinders and four horizontal floating boxes; the upper surface of the top plate is used to install and carry equipment, and the lower surface is connected to the four support columns. The bottom ends of the four support columns are respectively connected to the centers of the four vertical floating cylinders, and the four vertical floating cylinders are connected into a ring through the four horizontal floating boxes. Preferably, the floating platform can be made of steel structure.

[0008] In one embodiment, the four vertical floating cylinders are located at the four vertices of a square, and the center positions of the vertical floating cylinders are connected to the center positions of the upper support columns.

[0009] In one embodiment, the four vertical buoys communicate with the internal cavities of the four horizontal floating boxes, which are used to store ballast water and have a water outlet and a water inlet. Pumps can be arranged at the water outlet and the water inlet. By adjusting the mass of the ballast water, the tension of the tension legs of the floating platform can be ensured to be within a certain range under different water levels, guaranteeing the safety of the tension legs. At the same time, it is ensured that under different water level conditions, the four support columns are located at the water surface line of the sea level. Since the area of the water plane is only the cross-sectional area of the outer diameter of the support columns, the change in buoyancy caused by the water level change is small, thereby reducing the fluctuation range of the tension of the tension legs and ensuring the safety and stability of the tension leg system.

[0010] In one embodiment, the four tension legs form the mooring part of the system. Each tension leg includes a connection key, a tension tendon, a connector, and a connecting steel cable; the tension tendon is connected to the floating platform through the connection key, specifically, it can be connected to the center of the bottom surface of the upper vertical buoy. The tension tendon is connected to a number of connecting steel cables through the connector, and the connecting steel cable is connected to the screw pile. Specifically, the lower end of the tension tendon is connected to the connector, and the connector is then connected to the top of the lower screw pile through the connecting steel cable. The tension transmitted by the upper tension tendon is evenly distributed on the screw pile through the connector and the connecting steel cable. Preferably, the tension tendon can be a steel cable.

[0011] In one embodiment, the connector is a steel cable anchoring clamp. The tension transmitted by the upper tension tendon is evenly distributed on the screw pile through the connector and the connecting steel cable. The connector is responsible for connecting a number of steel cables, and a steel cable anchor capable of clamping multiple steel cables simultaneously is adopted.

[0012] In one embodiment, the four screw piles form the anchoring part of the system. Each screw pile includes a bottomless steel pipe pile and a number of spiral plates; the spiral plates are made of steel and are welded to the lower part of the bottomless steel pipe pile.

[0013] In one embodiment, the spiral plate adopts a blade-type steel spiral plate, which is spiral-shaped and welded to the lower part of the bottomless steel pipe pile. The anti-pulling capacity can be greatly improved by installing the spiral plate.

[0014] In one embodiment, there are multiple spiral plates on the same bottomless steel pipe pile, and the anti-pulling capacity is improved by installing the spiral plates.

[0015] In one embodiment, the bottomless steel pipe pile and a number of spiral plates are buried in the seabed. The screw pile can be specifically installed on the seabed by a method of simultaneous rotation and pressing. The top of the bottomless steel pipe pile exposes a certain distance from the seabed and is connected to the tension leg, specifically, it is connected to the tension tendon through the connecting steel cable and the connector.

[0016] Compared with the prior art, the beneficial effects of the present utility model are:

[0017] The floating platform design proposed by the present utility model ensures that under different water level conditions, the sea level water line is always located at the position of the support column. Since the area of the water plane is only the cross-sectional area of the outer diameter of the support column, the change in buoyancy caused by the water level change is small, thereby reducing the fluctuation of the tension force on the tension tendon. In addition, the tension force of the tension leg can be further adjusted by adjusting the mass of the ballast water, effectively improving the stability and safety of the floating platform in the sea area with large water level changes and strong wave force influence.

[0018] The present utility model proposes a solution that combines a tension leg mooring system with a screw pile anchoring system. The design of the screw plate greatly improves the uplift bearing capacity of the screw pile, thereby ensuring that sufficient anchoring force can be provided when a large tension appears. At the same time, compared with ordinary steel pipe piles, the main pile diameter of the screw pile is greatly reduced, reducing the material cost. In addition, the installation method combining rotation and pressing makes the whole installation process more convenient and efficient, achieving cost reduction and efficiency improvement of the anchoring foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments in accordance with the present utility model, and are used together with the specification to explain the principles of the present utility model, and do not constitute an improper limitation of the present utility model.

[0020] Figure 1 It is an overall schematic diagram of a tension leg - screw pile mooring system for a floating offshore platform of the present utility model.

[0021] Figure 2 It is a detailed structure diagram of the floating platform of the present utility model.

[0022] Figure 3 It is a detailed structure diagram of the tension leg and screw pile of the present utility model.

[0023] In the figure:

[0024] 1. Floating platform; 2. Tension leg; 3. Screw pile; 101. Top plate; 102. Support column; 103. Vertical floating cylinder; 104. Horizontal floating box; 201. Connecting key; 202. Tension tendon; 203. Connector; 204. Connecting steel cable; 301. Steel pipe pile without bottom; 302. Screw plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following further describes in detail the specific embodiments of the present utility model with reference to the drawings. These embodiments are only used to illustrate the present utility model and are not intended to limit the present utility model.

[0026] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model 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 construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0027] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The present invention relates to a catenary leg - screw pile mooring system for a floating offshore platform suitable for sea areas with large water level variations and large wave forces on the platform, which can economically, reasonably and effectively solve the problems described in the background art.

[0029] Embodiment 1

[0030] See Figures 1-3 , this embodiment provides a catenary leg - screw pile mooring system applicable to a floating offshore wind turbine. The system mainly consists of a floating platform 1, catenary legs 2, screw piles 3, and upper floating wind turbine equipment. Specifically, the floating platform 1 floats on the sea surface, and its upper part is connected to the wind turbine tower through a flange welded on the top plate, thereby carrying the floating wind turbine equipment and providing buoyancy for it. The bottom of the floating platform 1 is connected to the top end of the catenary leg 2 through a connection key 201. The bottom end of the catenary leg 2 is connected to the top end of the screw pile 3 through a connector 203 and a connecting steel cable 204. A screw pile 3 is anchored to the seabed directly below each connection key 201, and a certain length is left at the top of the screw pile 3 for connecting the catenary leg 2.

[0031] The screw pile 3 is a new type of pile foundation, which has the advantages of simple construction, environmental friendliness, short construction period, high bearing capacity, and easy recovery. In this embodiment, the screw pile 3 is used as the anchoring foundation for the floating photovoltaic, which can greatly reduce the manufacturing and offshore construction costs on the premise of ensuring structural safety, and achieve cost reduction and efficiency improvement in the offshore photovoltaic industry.

[0032] Specifically, the screw pile 3 of the present utility model comprises a bottomless steel pipe pile 301 and a plurality of screw plates 302; the screw plates 302 are made of steel, are spiral in shape, and are welded to the lower part of the bottomless steel pipe pile 301. In this embodiment, there are 2 screw plates 302 on the same bottomless steel pipe pile 301.

[0033] In the tension leg-screw pile mooring system of the floating offshore wind turbine of this embodiment, the buoyancy provided by the floating platform 1 is mainly used to bear the self-weight of the floating platform 1 and the load of the wind turbine equipment, and the remaining buoyancy is mainly to provide a tension force for the tension leg 2, so that it has greater horizontal and vertical stiffness to limit the motion response of the platform. The tension leg 2 provides a pulling force to limit the horizontal and vertical movements of the floating platform 1, and the screw pile 3 provides an anchoring pulling force for the tension leg 2 to ensure the stability of the tension leg 2 itself. Due to the existence of the anchor plate 302, the vertical uplift bearing capacity that the screw pile can provide is greatly increased. Therefore, the tension leg-screw pile mooring system effectively controls the motion response of the platform, and on the premise of ensuring the stability and safety of the platform, reduces the construction and installation costs of the platform.

[0034] See Figure 2 , in this example, the floating platform 1 comprises a top plate 101, four support columns 102, four vertical floating cylinders 103 and four horizontal floating boxes 104; a flange is installed on the upper part of the top plate 101 to be connected with the floating wind turbine, and the lower surface is connected with the four support columns 102. The bottoms of the four support columns 102 are respectively connected with the centers of the four vertical floating cylinders 103. The four vertical floating cylinders 103 are connected to each other through the four horizontal floating boxes 104 to form a closed loop. Preferably, the four vertical floating cylinders 103 are located at the four vertices of a square, and the center positions of the vertical floating cylinders 103 are connected with the center positions of the upper support columns 102. The internal cavities between the four vertical floating cylinders 103 and the four horizontal floating boxes 104 are communicated to store ballast water, and have a water outlet and a water inlet, and the quality of the ballast water can be adjusted through a ballast water pump to ensure that the tension force of the tension leg 2 of the floating platform 1 is within a certain range under different water levels, thereby improving the safety and stability of the platform.

[0035] In this embodiment, the floating platform 1 has the following characteristics: Different from the traditional tension leg platform, the floating platform of the present utility model is designed to ensure that the sea level water line is always located at the position of the support column 102 under different water level conditions. Since the water plane area is only the cross-sectional area of the outer diameter of the support column 102, the change in buoyancy caused by the water level change is small, so the tension fluctuation range of the tension leg is small. This design enhances the safety of the tension leg, while reducing the wave force on the platform, significantly improving the stability of the platform, and reducing the motion response of the platform. After the platform stability is enhanced, the wind power generation efficiency is also improved. At the same time, the influence of the water level change on the buoyancy is effectively controlled, so that the tension change range of the tension leg 2 is further reduced. In addition, by adjusting the mass of the ballast water in the platform, the tension of the tension leg 2 can be flexibly adjusted, thereby further improving the safety and stability of the platform and reducing the construction cost of the platform.

[0036] See Figures 2-3 , the tension leg 2 includes a connection key 201, a tension tendon 202, a connector 203 and a connection cable 204. The tension tendon 202 is connected to the upper vertical floating barrel 103 through the connection key 201, and is connected to the lower screw pile 3 through the connector 203 and a plurality of connection cables 204. The design of the connector 203 and the connection cable 204 can evenly transmit the tension force transmitted by the tension tendon 202 to the top of the bottom screw pile 3, so that the resultant force of the tension force received by the screw pile 3 acts on its axis, thereby improving the bearing capacity provided by the screw pile 3. When the platform is working, the tension tendon 202 always remains in a tensioned state and bears a certain tension force to control the motion response of the floating platform 1.

[0037] Preferably, the tension tendon 202 is made of a cable, which is lighter in weight and lower in cost compared with the traditional steel pipe type tension tendon.

[0038] Preferably, see Figure 3 , the screw pile 3 is composed of a bottomless steel pipe pile 301 and two screw plates 302. The screw plates 302 are welded to the middle and bottom of the bottomless steel pipe pile 301. When the screw pile 3 bears the tension force transmitted by the tension tendon 202, in addition to the friction between the bottomless steel pipe pile 301 and the soil, the biting effect between the screw plates 302 and the soil further expands the bearing range of the pile, significantly increasing the uplift bearing capacity of the screw pile 3, especially suitable for bearing the vertical uplift force generated by the tension leg floating platform. This design can reduce the size of the main pile and the material cost on the premise of ensuring the anchoring force required by the platform.

[0039] The installation of the screw pile 3 is carried out by combining rotation and pressing. During the installation process, by applying a downward pressure and torque simultaneously to the top of the screw pile 4, the stable installation of the pile body can be achieved. Compared with the driving installation method of traditional steel pipe piles, this method has the advantages of less noise and vibration, can significantly improve the installation speed, and reduce the interference to the surrounding environment. In addition, this efficient installation method also effectively reduces the anchoring cost of the floating platform, further enhancing the overall economy.

[0040] Embodiment 2:

[0041] This embodiment provides a tension leg-screw pile mooring system applicable to floating offshore photovoltaic power generation. The main difference from Embodiment 1 lies in the different equipment above the top plate 101. Based on the upper top plate, an upper deck with a larger installation area and a greater height from the sea level is installed, and photovoltaic panels are installed on the upper deck. The rest of the structure is the same as that in Embodiment 1.

[0042] In summary, for the tension leg-screw pile mooring and anchoring system of the floating offshore platform provided in this example, the sea level water line is always located at the position of the support column, significantly reducing the waterplane area of the platform. On the one hand, this design reduces the wave force received by the platform, thereby reducing the motion response of the platform and ensuring the stable operation of the upper equipment; on the other hand, since the change in buoyancy caused by the water level change is small, the change range of the tension of the tension leg is also controlled, thus enhancing the safety of the tension leg. At the same time, by adjusting the ballast water quality of the platform, the tension of the tension leg can be further accurately controlled, further improving the overall safety of the platform. In terms of bottom anchoring, the spiral plate biting effect between the screw pile and the soil body is adopted, greatly enhancing its vertical uplift resistance, especially suitable for coping with the vertical uplift force transmitted by the tension leg. This anchoring method not only improves the safety of the platform but also significantly reduces the construction cost of the anchoring foundation, achieving a more economical and efficient solution.

[0043] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and substitutions can be made, and these improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A tension leg-screw pile mooring system suitable for a floating offshore platform, characterized in that: It comprises a floating platform (1), a tension leg (2) and a screw pile (3); The floating platform (1) floats on the sea surface and is used to carry equipment and provide buoyancy for the equipment. Its lower part is connected to the top of the tension leg (2), and the bottom end of the tension leg (2) is connected to the top of the screw pile (3). The screw pile (3) is anchored to the seabed and a part of the upper part is reserved for connection with the tension leg (2). The screw pile (3) provides tension for fixing the bottom end of the tension leg, and the tension leg (2) provides tension for limiting the horizontal and vertical movement of the floating platform (1).

2. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 1, characterized in that: The floating platform (1) comprises a top plate (101), four supporting columns (102), four vertical buoys (103) and four horizontal pontoons (104); the upper surface of the top plate (101) is used to install bearing equipment, and the lower surface is connected to the four supporting columns (102); the bottom ends of the four supporting columns (102) are respectively connected to the centers of the four vertical buoys (103); and the four vertical buoys (103) are connected to form a ring through the four horizontal pontoons (104).

3. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 2, characterized in that: The four vertical pontoons (103) are located at the four vertices of the square, and the center position of the vertical pontoon (103) is connected to the center position of the upper support column (102).

4. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 2, characterized in that: The four vertical buoys (103) are connected to the internal cavities of the four horizontal pontoons (104), are used to store ballast water and have a water outlet and a water inlet. The quality of the ballast water is adjusted to ensure that the tension force of the tension legs (2) of the floating platform (1) is within a certain range at different water levels, and the four support columns (102) are located at the sea level water surface line.

5. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 1, characterized in that: The tension leg (2) comprises a connection key (201), a tension bar (202), a connector (203) and a connecting steel cable (204); the tension bar (202) is connected to the floating platform (1) via the connection key (201), and is connected to a plurality of connecting steel cables (204) via the connector (203); and the connecting steel cables (204) are connected to the screw pile (3).

6. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 5, characterized in that: The connector (203) is a steel cable anchoring clamp.

7. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 1, characterized in that: The screw pile (3) comprises a bottomless steel pipe pile (301) and a plurality of screw discs (302); the screw discs (302) are made of steel and welded to the lower part of the bottomless steel pipe pile (301).

8. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 7, characterized in that: The screw disc (302) is a blade-type steel screw disc, which is spiral-shaped and welded to the lower part of the bottomless steel pipe pile (301).

9. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 7 or 8, characterized in that: There are multiple screw discs (302) on the same bottomless steel pipe pile (301), and the pull-out resistance is improved by adding screw discs (302).

10. The tension leg-screw pile mooring system suitable for a floating offshore platform according to claim 7 or 8, characterized in that: The bottomless steel pipe pile (301) and a plurality of screw discs (302) are buried in the seabed, wherein the top of the bottomless steel pipe pile (301) is exposed from the seabed by a certain distance and is connected to the tension leg (2).

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