CN108454799B - A kind of offshore wind farm buoyant foundation transportation by driving construction method - Google Patents

Abstract

The invention belongs to the technical field of offshore wind power foundations, and discloses a floating construction method for offshore wind power floating foundations. First, a floating platform and a mooring system are prefabricated on land and temporarily fixed by inclined mooring lines and straight mooring lines; The system-floating platform-tower-wind turbine is floated and towed as a whole; ballast is applied to sink the anchor foundation and embedded in the seabed for fixation; the floating platform installed with the upper wind turbine tower is sunk to the design draft position, and the anchor Mooring line and straight mooring line; discharge the water body in some cabins in the buoyancy tank; finally adjust the center of gravity position of the offshore wind power floating foundation. The invention can provide sufficient buoyancy stability during towing, and is less affected by wave loads in the in-position state; it realizes the layered tension system on the water, and reduces the difficulty of installing mooring lines underwater; Pull-out resistance, and penetrate into the seabed through surcharge and internal and external pressure difference, easy construction.

Description

A floating construction method for offshore wind power floating foundation

technical field

The invention belongs to the technical field of offshore wind power foundations, and in particular relates to a floating construction method for offshore wind power floating foundations, which has good stability, convenient construction and installation, and low engineering and installation costs.

Background technique

The concept of floating foundation comes from the deep-sea oil and gas development platform, which means that the foundation is not in direct contact with the seabed, but is connected to the seabed through anchor cables or cables, so that the wind turbine can move freely in a relatively fixed area. The foundation is currently mainly in the research and development and demonstration stage, but it has strong adaptability to the marine environment. Compared with the implanted foundation, the construction is less difficult and the operation and maintenance costs are lower. Therefore, it has a good application prospect in the development of deep-sea wind power.

Compared with offshore waters, the deep sea environment is harsher, and there are various hydrological phenomena such as ocean currents, waves, tides, and internal waves, as well as long-term physical and chemical effects such as corrosion, erosion, and emptying. More stringent requirements were put forward. Considering the factors of technical difficulty and construction cost, fixed foundations are no longer applicable, and deep-sea wind farms mainly use floating foundations.

The main types of existing offshore wind power floating foundations are: Spar type, TLP type and semi-submersible type foundation. The Spar type foundation has a small water surface and is less affected by wave loads. It is suitable for deep sea areas and is inconvenient to install and move; the TLP type foundation has better motion performance, and the mooring uses tension tendons, which are expensive and limited by water depth; The semi-submersible foundation can be floated and towed, but its large water plane makes it greatly affected by wave loads and has poor stability. The above foundation forms have their own disadvantages in terms of stability and economy, and the mooring lines of the three foundation types all need to be installed underwater, making construction difficult.

Contents of the invention

The present invention aims to solve the technical problem of complex and high cost in the underwater construction process, and provides a floating construction method for offshore wind power floating foundations, which is convenient for construction and low in installation cost, and can enable better application of offshore wind power floating foundations in actual engineering.

In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

A floating construction method for an offshore wind power floating foundation is carried out according to the following steps:

(1) Land prefabricated floating platform and mooring system;

The floating platform includes a column, a pontoon, and an inclined strut that are all hollow structures. The upper end of the column is connected to the fan tower through a flange, and the lower end of the column is connected to the pontoon. The column and the pontoon A plurality of oblique struts uniformly distributed in the circumferential direction are connected between them; the center of the buoyancy tank is provided with a first reserved channel communicating with the column, and a ring-toward inner plate is arranged inside the first reserved channel, and the ring The inner plate is fixedly connected with the bottom plate of the pontoon; the inside of the pontoon is provided with a radial dividing plate and a circumferential dividing plate, and the radial dividing plate and the circumferential dividing plate separate the The interior of the buoyancy tank is divided into multiple sub-chambers, and each sub-chamber is equipped with a valve system that can replace water and air; each radial sub-chamber is provided with a second reserved hole, and the number of the second reserved hole is It is the same as the inclined strut and is connected and communicated with the lower end of the inclined strut one by one, and the upper end of the inclined strut is communicated with the column;

The mooring system includes an anchor foundation, an inclined mooring line and a straight mooring line. The anchor foundation includes an anchor plate body, the upper edge of the anchor plate body is provided with a tube wall, and the lower edge is provided with a tube skirt; the number of the straight mooring lines The number of the second reserved channel and the inclined brace is the same, and the lower end of the straight mooring line corresponding to the position of the second reserved channel is anchored to the anchor plate of the anchor foundation; the inclined mooring The number of lines is twice that of the straight mooring line, and the lower end of the inclined mooring line is anchored to the anchor plate of the anchor foundation at a position corresponding to the outer periphery of the first reserved tunnel;

(2) Extend the upper end of the inclined mooring line into the first reserved channel inside the buoyancy tank and temporarily fix it on the ring inner plate; pass the upper end of the straight mooring line through the buoy The second reserved channel inside the box is passed through the inclined strut to the inside of the column and temporarily fixed to the column;

(3) Towing and transporting the temporarily fixed mooring system, the floating platform, and the wind turbine tower installed on the floating platform to the operating sea area;

(4) apply ballast to sink the anchor foundation, and embed the anchor foundation in the seabed for fixing by surcharge and internal and external pressure difference;

(5) Inject water into part of the cabins in the buoyancy tank through the valve system of water-air replacement, so that the floating platform with the upper fan tower will lose part of its buoyancy and sink. When sinking to the design draft position, follow the The preset lengths of the slanted mooring line and the straight mooring line, the upper end of the slanting mooring line is anchored to the ring inner plate, and the upper end of the straight mooring line is anchored to the column; at this time, the The oblique mooring line is arranged obliquely from the outside to the center from bottom to top between the anchor foundation and the buoyancy tank, and the straight mooring line is vertically arranged between the anchor foundation and the buoyancy tank;

(6) the water body in the partial cabin in the described buoyancy tank is discharged through the valve system of water vapor replacement;

(7) Discharge the water body in the first reserved channel, the second reserved channel and the inclined strut through high-pressure pumping, and seal the bottom of the buoyancy tank;

(8) Adjust the position of the center of gravity of the offshore wind power floating foundation through some cabins in the buoyancy tank.

Preferably, the second reserved hole is smoothly connected with the inclined strut in an arc.

Preferably, the angle between the inclined mooring line and the vertical direction is 3°-60°.

Preferably, each anchor point of the inclined mooring line and the straight mooring line is provided with a maintenance device.

Preferably, the exposed parts of the inclined mooring line and the straight mooring line are wrapped with rubber sleeves.

The beneficial effects of the present invention are:

(1) The offshore wind power floating foundation floating construction method of the present invention, its floating platform combines the design of the column on the small waterline surface and the buoyancy box on the large waterline surface to ensure that the foundation is floated by the large waterline surface when towed. The tank provides sufficient buoyancy. At the same time, the buoyant tank is submerged underwater when the fan is in place. The columns on the small water surface are less affected by wave loads, ensuring the stability of the foundation after construction.

(2) The floating construction method of the offshore wind power floating foundation of the present invention, the mooring system is designed by combining the straight mooring line and the inclined mooring line, and the straight mooring line provides better heave and rotation performance, and the inclined mooring line The mooring line provides a large horizontal restraint force, so that the movement response of the foundation in all directions is small and the stability is good; the upper end of the straight mooring line is anchored to the column, and the upper end of the inclined mooring line is fixed on the inner plate of the pontoon to realize layered tension on the water The system reduces the difficulty of installing mooring lines underwater and is convenient for construction; straight mooring lines and inclined mooring lines are made of steel strands, which is economical.

(3) In the offshore wind power floating foundation floating construction method of the present invention, the anchor foundation of the mooring system utilizes the frictional resistance provided by the ballast weight and the tube skirt to provide pullout resistance, and is used for the positioning of the straight mooring line and the inclined mooring line, and the anchor foundation The upper part can be filled with sand and ballasted, and the lower part has a tube skirt. The large water plane allows it to be towed to the operating waters, and can penetrate into the seabed through surcharge and internal and external pressure differences, which is convenient for construction.

Description of drawings

Fig. 1 is the schematic diagram of the three-dimensional structure of the offshore wind power floating foundation involved in the method of the present invention;

Fig. 2 is a schematic diagram of mooring line distribution of offshore wind power floating foundation involved in the method of the present invention;

Fig. 3 is the front view of offshore wind power floating foundation involved in the method of the present invention;

Fig. 4 is a top view of the offshore wind power floating foundation involved in the method of the present invention.

In the figure: 1. Column, 2. Inclined strut, 3. Floating tank, 4. Straight mooring line, 5. Inclined mooring line, 6. Anchorage foundation, 7. Second reserved channel, 8. First reserved Channel, 9, radial subdivision plate, 10, circumferential subdivision plate, 11, circumferential inner plate.

Detailed ways

In order to further understand the invention content, characteristics and effects of the present invention, the following examples are given, and detailed descriptions are as follows in conjunction with the accompanying drawings:

This embodiment discloses a floating construction method for offshore wind power floating foundations, which is carried out according to the following steps:

(1) As shown in Figures 1 to 4, the offshore wind power floating foundation is composed of a floating platform and a mooring system, and the floating platform and the mooring system are prefabricated on land first.

The floating platform includes a column 1, an inclined strut 2, and a pontoon 3. The upper end of the column 1 is connected to the fan tower through a flange, and the lower end of the column 1 is fixedly connected to the pontoon 3. A plurality of inclined struts 2. Considering that the cabin and blades of offshore wind turbines are heavy and are 80-100m above the water surface, in order for the wind turbines to generate electricity normally, it is necessary to ensure the stability of the foundation under the combined action of wind and waves and the ability to resist wind and wave loads. The column 1 and the buoyancy tank 3 are made of steel structure, concrete structure or other light materials, which can carry a large wind load. The combination design of small waterline surface column 1 and large waterline surface pontoon 3 provides sufficient buoyancy stability by large waterline surface pontoon 3 to realize the floating and towing of the floating platform-tower-wind turbine as a whole, which is convenient for installation and transportation ; And when in position state, the buoyancy tank 3 dives below the water surface, and the column 1 of the small water plane is positioned on the water surface, so as to reduce the influence of the wave load. The inclined struts 2 are obliquely connected between the column 1 and the floating tank 3, so as to strengthen the connection structure between the column 1 and the floating tank 3, and provide horizontal and vertical bearing capacity for the upper wind power structure.

The column 1 is a cylindrical structure with a cavity, its diameter is 8m, its height is 20m, and its wall thickness is 50mm.

The floating tank 3 is a flat cylindrical structure with a cavity, its diameter is 33m, its height is 10m, and its wall thickness is 15mm. The center of the buoyancy tank 3 is provided with a first reserved channel 8 with a diameter of 8 m. The first reserved channel 8 communicates with the column 1 and its diameter is the same as that of the column 1 . Inside the first reserved channel 8, there is a ring inner plate 11 with a diameter of 6m and a wall thickness of 30mm. The inner plate 11 is fixedly connected with the bottom plate of the buoyancy tank 3 for fixing the inclined mooring line 5. The interior of the buoyancy tank 3 is provided with four radially evenly distributed radial division panels 9 and one circumferential division panel 10, the radial division panel 9 and the circumferential division panel 10 divide the interior of the buoyancy tank 3 into inner, There are four sub-chambers in each of the outer two circles, and each sub-chamber is equipped with a valve system that can replace water and air. The buoyancy tank 3 can adjust the position of the center of gravity by adding water ballast to each sub-chamber to ensure the stability of the basic tow. A second reserved hole 7 is provided at the same position on each radial subdivision plate 9 , and the four second reserved holes 7 communicate with the four inclined struts 2 respectively. The second reserved channel 7 is smoothly connected with the inclined strut 2 in a certain arc, so as to avoid the damage of the mooring line caused by stress concentration when the mooring line is stretched and stressed, and affects the normal operation of the system. The second reserved channel 7 and the first reserved channel 8 can prevent the mooring line from contacting with water, and ensure that the mooring anchor point is not damaged.

The inclined strut 2 is a hollow long columnar structure with a diameter of 2m. Four inclined struts 2 are evenly distributed in the circumferential direction around the column 1, the upper end of each inclined strut 2 is fixedly connected to the upper end of the side wall of the column 1 and communicates with the column 1, and the lower end is fixedly connected to the outer surface of the upper surface of the buoyancy tank 3 position and communicate with the second reserved channel 7.

The mooring system includes straight mooring lines 4 , inclined mooring lines 5 and anchoring foundations 6 , and the lower ends of the four straight mooring lines 4 and eight inclined mooring lines 5 are all anchored to the anchoring foundation 6 . The number of straight mooring lines 4 is the same as the number of the second reserved tunnel 7 and the number of inclined struts 2, generally 3-8. The lower end of the straight mooring line 4 is anchored to the anchor foundation 6 directly below the second reserved tunnel 7, so that the upper ends of the four straight mooring lines 4 are anchored and vertically arranged between the buoy 3 and the anchor foundation 6. The number of oblique mooring lines 5 is twice that of the straight mooring lines 4, generally 6-16. The lower end of the inclined mooring line 5 is anchored to the anchor foundation 6 at the position corresponding to the outer periphery of the first reserved tunnel 7, so that the eight inclined mooring lines 5 are from top to bottom from the center to the outside between the buoy box 3 and the anchor foundation 6. The same angle is radially inclined, and the angle between the inclined mooring line 5 and the vertical direction is within the range of 3° to 60°. The diameters of the straight mooring line 4 and the inclined mooring line 5 are both 167 mm, and steel strands, polyester fiber lines, etc. can be used; buoy balls are arranged on the upper ends before anchoring, so that they can pass through the second reserved tunnel 7 and the second One reserved channel 8 .

The anchoring foundation 6 includes a circular anchoring plate with a diameter of 40 m. The upper edge of the anchoring plate is provided with an annular tube wall with a height of 2 m, and the lower edge is provided with an annular tube skirt with a height of 5 m. The anchor plate is used to provide anchor points at the lower ends of the straight mooring line 4 and the inclined mooring line 5. The superstructure formed by the anchor plate and the tube wall can be filled with sand and ballasted, and the tube skirt penetrates into the seabed through the ballast load and the pressure difference between the inside and outside. The anchor foundation 6 can penetrate into the seabed through the heap load and the internal and external pressure difference, and the anchor foundation 6 utilizes the friction resistance provided by the ballast weight and the tube skirt to provide pullout force for the positioning of the straight mooring line 4 and the inclined mooring line 5 .

(2) Pass the upper ends of the four straight mooring lines 4 through the four second reserved channels 7 inside the buoyancy tank 3, and pass through the four inclined struts 2 to the inside of the column 1, and finally temporarily fix them on the side wall of the column 1 The inner surface. The upper ends of eight oblique mooring lines 5 extend into the inside of the first reserved tunnel 8 and are temporarily fixed on the ring inner plate 11 .

(3) After the upper wind turbine tower, floating platform and mooring system are all installed, the temporarily fixed mooring system, floating platform, and wind tower installed on the floating platform will be towed and transported to the operating sea area ; Utilize the buoyancy tank 3 and the anchor foundation 6 on the large water plane to provide buoyancy stability to realize the overall floating and towing of the mooring system-floating platform-tower-wind turbine;

(4) After the floating platform installed with the upper wind turbine tower and the mooring system are towed and transported to the operation sea area, ballast is applied to sink the anchor foundation 6 in the mooring system, and the anchor foundation 6 in the mooring system will sink through the heap load and the internal and external pressure difference. The foundation 6 is embedded in the seabed and fixed;

(5) Water is injected into the inner compartment of the buoyancy tank 3 through the valve system of water-air replacement, so that the floating platform installed with the upper fan tower loses part of its buoyancy and sinks, and the outer compartment of the buoyancy tank 3 is subdivided during the sinking process The indoor air provides a certain buoyancy to the foundation to ensure the stability of the floating foundation of offshore wind power; The upper end of the inclined mooring line 5 is anchored on the ring inner plate 11, and the upper end of the straight mooring line 4 is anchored on the inner surface of the side wall of the column 1. After anchoring, each anchor point is provided with a maintenance device. At this time, the oblique mooring line 5 is arranged obliquely from the outside to the center from bottom to top between the anchor foundation 6 and the buoyancy tank 3, and the angle between the oblique mooring line 5 and the vertical direction is within the range of 3° to 60°; The straight mooring line 4 is vertically arranged between the anchor foundation 6 and the buoyancy tank 3 . Thus, the straight mooring line 4 and the inclined mooring line 5 form a layered tension system above water, which reduces the difficulty of installing the mooring line underwater. The straight mooring line 4 provides good heave and rotation performance, and the oblique mooring line 5 provides greater horizontal restraint, and the radially inclined design reduces seabed area occupied and collision with seabed structures. Both the straight mooring line 4 and the inclined mooring line 5 are wrapped with rubber sleeves to avoid corrosion and damage in seawater.

(6) The water body in the sub-chamber of the inner ring of the buoyancy tank 3 is discharged through the valve system of water vapor replacement, so as to ensure the floating foundation of the offshore wind power has certain buoyancy stability;

(7) Bring the straight mooring line 4 into the second reserved channel 7 and the water body of the inclined strut 2, and the water body brought into the first reserved channel 8 by the inclined mooring line 5 is discharged through high-pressure pumping to seal the bottom of the buoyancy tank 3 , to ensure that the second reserved channel 7, the first reserved channel 8 and the inclined strut 2 are in a dry state;

(8) After being in place, the position of the center of gravity of the offshore wind power floating foundation is adjusted by injecting water into the outer ring sub-chambers of the buoyancy tank 3 to ensure safe and stable operation of the offshore wind power floating foundation.

In this way, the mooring system can effectively control the movement of the floating platform in the six degrees of freedom of heave, surge, sway, yaw, roll, and pitch, ensuring that the offshore wind power floating foundation has less movement Response, thus showing good dynamic performance, which greatly reduces the design requirements for wind turbines.

Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative and not restrictive. Those of ordinary skill in the art Under the enlightenment of the present invention, without departing from the purpose of the present invention and the scope of protection of the claims, personnel can also make specific changes in many forms, and these all belong to the protection scope of the present invention.

Claims (5)

1. A floating construction method for offshore wind power floating foundation, characterized in that, it is carried out according to the following steps: (1) Land prefabricated floating platform and mooring system; The floating platform includes a column, a pontoon, and an inclined strut that are all hollow structures. The upper end of the column is connected to the fan tower through a flange, and the lower end of the column is connected to the pontoon. The column and the pontoon A plurality of oblique struts uniformly distributed in the circumferential direction are connected between them; the center of the buoyancy tank is provided with a first reserved channel communicating with the column, and a ring-toward inner plate is arranged inside the first reserved channel, and the ring The inner plate is fixedly connected with the bottom plate of the pontoon; the inside of the pontoon is provided with a radial dividing plate and a circumferential dividing plate, and the radial dividing plate and the circumferential dividing plate separate the The interior of the buoyancy tank is divided into multiple sub-chambers, and each sub-chamber is equipped with a valve system that can replace water and air; each radial sub-chamber is provided with a second reserved hole, and the number of the second reserved hole is It is the same as the inclined strut and is connected and communicated with the lower end of the inclined strut one by one, and the upper end of the inclined strut is communicated with the column; The mooring system includes an anchor foundation, an inclined mooring line and a straight mooring line. The anchor foundation includes an anchor plate body, the upper edge of the anchor plate body is provided with a tube wall, and the lower edge is provided with a tube skirt; the number of the straight mooring lines The number of the second reserved channel and the inclined brace is the same, and the lower end of the straight mooring line corresponding to the position of the second reserved channel is anchored to the anchor plate of the anchor foundation; the inclined mooring The number of lines is twice that of the straight mooring line, and the lower end of the inclined mooring line is anchored to the anchor plate of the anchor foundation at a position corresponding to the outer periphery of the first reserved tunnel; (2) Extend the upper end of the inclined mooring line into the first reserved channel inside the buoyancy tank and temporarily fix it on the ring inner plate; pass the upper end of the straight mooring line through the buoy The second reserved channel inside the box is passed through the inclined strut to the inside of the column and temporarily fixed to the column; (3) Towing and transporting the temporarily fixed mooring system, the floating platform, and the wind turbine tower installed on the floating platform to the operating sea area; (4) apply ballast to sink the anchor foundation, and embed the anchor foundation in the seabed for fixing by surcharge and internal and external pressure difference; (5) Inject water into the sub-chambers inside the buoyancy tank through the valve system of water-air replacement, so that the floating platform equipped with the fan tower loses part of its buoyancy and sinks. When sinking to the design draft position, follow the instructions The preset lengths of the slanted mooring line and the straight mooring line, the upper end of the slanting mooring line is anchored to the ring inner plate, and the upper end of the straight mooring line is anchored to the column; at this time, the The oblique mooring line is arranged obliquely from the outside to the center from bottom to top between the anchor foundation and the buoyancy tank, and the straight mooring line is vertically arranged between the anchor foundation and the buoyancy tank; (6) the water body in the sub-chamber inside the buoyancy tank is discharged through the valve system of water vapor replacement; (7) Discharge the water body in the first reserved channel, the second reserved channel and the inclined strut through high-pressure pumping, and seal the bottom of the buoyancy tank; (8) The center of gravity of the offshore wind power floating foundation is adjusted through the sub-chambers inside the buoyancy tank. 2 . The floating construction method for offshore wind power floating foundations according to claim 1 , wherein the second reserved tunnel and the inclined strut are smoothly connected in an arc. 3 . 3 . The floating construction method for offshore wind power floating foundations according to claim 1 , wherein the angle between the inclined mooring line and the vertical direction is 3° to 60°. 4 . 4. The floating construction method for offshore wind power floating foundations according to claim 1, characterized in that, each anchor point of the inclined mooring line and the straight mooring line is provided with a maintenance device. 5 . The floating construction method for offshore wind power floating foundations according to claim 1 , wherein the exposed parts of the inclined mooring lines and the straight mooring lines are wrapped with rubber sleeves. 5 .