CN108677995B - Offshore wind turbine single pile foundation with suction caisson and tensioning mooring system - Google Patents

Abstract

The invention discloses an offshore wind turbine single pile foundation with a suction caisson and a tensioned mooring system, which includes a single pile foundation. The single pile foundation is provided with a suction caisson and a tensioned mooring system; the suction The main body of the caisson is an annular structure, with an axial penetrating shaft hole in the middle of the annular structure. The suction caisson is sleeved on the single pile foundation through the shaft hole, and the inner wall of the shaft hole is connected to the single pile through a grouting connection section. The outer surface of the pile foundation is connected, and a number of reinforced ribs are provided between the inner wall and the outer wall of the suction caisson; the tensioned mooring system includes a mooring point located on the single pile foundation, and a mooring point located on the single pile foundation. There are at least two anchor foundations on the surrounding seabed, which are connected to mooring points through anchor lines. The invention increases the stiffness of the single pile foundation at the seabed by arranging an annular suction caisson foundation at the connection point between the single pile foundation and the seabed, and controls the horizontal displacement and dynamic response of the single pile foundation through a tensioning mooring system.

Description

An offshore wind turbine monopile foundation with suction caissons and tensioned mooring systems

Technical field

The present invention relates to the field of offshore wind turbine foundation systems, and specifically to an offshore wind turbine monopile foundation with a suction caisson and a tensioned mooring system.

Background technique

With the rapid development of the global wind power industry and the maturity of onshore wind power development technology, accelerating the development of offshore wind power is the main development trend of the current wind power market. Compared with land wind energy, ocean wind energy has the advantages of high quality, stability and low interference. However, due to the particularity of the marine environment, there is still a certain gap in the development speed and scale of offshore wind power compared with onshore wind power. Mainly because the equipment required for offshore wind power development is more complex than onshore wind power, and offshore installation costs are higher. Developing and improving offshore wind power related equipment, reducing costs and improving construction techniques are of great significance to the development of offshore wind power.

As the main development equipment for offshore wind power, one of the major investments in offshore wind turbines is its foundation, accounting for about 1/5 of the total cost. The choice of wind turbine foundation directly determines the stability and economy of the offshore wind turbine. Depending on the working water depth of offshore wind turbines, the selection of wind turbine foundations is different. From shallow water to deep water, the foundations that can be used are gravity foundation (<20m), single pile foundation (20m-40m), tripod foundation (30m-50m), jacket foundation (30m-50m), suction cylinder foundation and Mooring foundation (>50m), etc. About 75% of the world's offshore wind turbines currently use monopile foundations. The single pile foundation is generally a large diameter steel pipe pile with a diameter of 4-6m, and the burial depth is generally 20-40m depending on the geological conditions and water depth. Compared with other wind turbine foundation forms, the single-pile foundation structure is simple and easy to install, has a simple process and is economical, so it has been widely used.

However, because it mainly bears the horizontal load of wind and waves and has low bending stiffness, the single pile foundation still has weaknesses such as excessive upper displacement and large dynamic response. Especially in the special case where the soil on the upper part of the seabed is insufficient in strength and the silt layer is thick, there may be problems such as overturning caused by insufficient stability and instability caused by large displacement of the pile body.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the existing technology and provide an offshore wind turbine monopile foundation that uses an annular suction caisson and a tensioned mooring system as auxiliary. By combining the currently more mature offshore tensioned mooring system, Marine anchor foundations and suction caisson foundations combine the advantages of various marine foundations to solve the current problems of insufficient horizontal bearing capacity, large horizontal displacement, poor bending resistance and large dynamic response of single pile foundations. This combination foundation form is simple and economical to construct, and expands the applicable water depth range of the single pile foundation. It is especially suitable for offshore wind turbines under special soil conditions where the upper part of the seabed has insufficient soil strength and a thick silt layer.

The technical problems solved by the present invention can be achieved by adopting the following technical solutions:

An offshore wind turbine monopile foundation with a suction caisson and a tensioned mooring system, including a monopile foundation, on which a suction caisson and a tensioned mooring system are provided;

The main body of the suction caisson is an annular structure, and an axial hole is provided in the middle of the annular structure. The suction caisson is sleeved on the single pile foundation through the axis hole, and the inner walls of the axis hole are connected by grouting. The section is connected to the outer surface of the single pile foundation, and a number of reinforcing ribs are provided between the inner wall and the outer wall of the suction caisson;

The tensioned mooring system includes a mooring point located on a monopile foundation and at least two anchoring foundations set on the seabed around the monopile foundation. The anchoring foundation is connected to the mooring cables on the monopile foundation through anchor lines. Points are connected and tensioned.

The distance between the inner wall of the shaft hole and the outer surface of the single pile foundation is 1.5 times the wall thickness of the single pile foundation.

The reinforcing ribs are distributed from the top of the suction caisson to the bottom of the suction caisson. The distribution density of the reinforcing ribs in the top 1/3 of the suction caisson is greater than the distribution density of the reinforcing ribs in the bottom 2/3 of the suction caisson.

The suction caisson has a negative pressure installation component, which includes a negative pressure device and a water pumping hole arranged on the top. After the negative pressure installation of the suction caisson is completed, 1/3 of the top of the suction caisson is higher than the seabed.

One end of the anchor line is connected to the mooring point on the single pile foundation, and the other end of the anchor line is connected to the anchor foundation in the seabed. The anchor line is in a tensioned state, and the angle between the anchor line and the horizontal plane is between 30°-60°. ; The number of anchor lines is an even number and is symmetrically and evenly arranged around the single pile foundation.

The anchoring foundation includes suction anchors, suction penetration plate anchors, normal load-bearing anchors and dynamic penetration anchors.

The construction steps of the offshore wind turbine single pile foundation are as follows:

1) Place the suction caisson on the seabed, and then pass the main body of the single pile foundation through the shaft hole of the suction caisson;

2) Install the single pile foundation to the specified depth, and complete the connection between the shaft hole of the suction caisson and the outer surface of the single pile foundation through the grouting process;

3) Install the suction caisson to the design height through the negative pressure assembly of the suction caisson;

4) Arrange anchor foundations on the seabed around the monopile foundation, and connect and tighten the anchor foundations through anchor lines and mooring points on the monopile foundation.

Compared with the prior art, the beneficial effects of the present invention are:

1. This invention combines the advantages of suction caisson foundation, deep water anchoring system, ocean anchor foundation and single pile foundation to form a new type of foundation; through the auxiliary installation of suction caisson foundation, the anti-overturning ability of single pile foundation at the seabed is increased. ;Use the tensioned mooring system as an auxiliary to increase the usable water depth of the single pile foundation; at the same time, solve the cost increase problem caused by the increase in the wall thickness and diameter of the single pile foundation due to the use of large-capacity offshore wind turbines;

2. Through the assistance of the tensioned anchoring system, the present invention transfers the load received on the single pile foundation to the anchor foundation, improves the stability of the single pile foundation, increases the bending resistance and load-bearing capacity of the single pile foundation, and reduces The horizontal displacement and dynamic response of the single pile foundation are reduced.

3. The present invention enables single pile foundations to be used for offshore wind turbines in waters with water depths exceeding 40 meters, providing a more economical and effective choice for the foundation form of offshore wind turbines in waters of 40 meters to 60 meters; it is especially suitable for areas with insufficient soil strength on the upper part of the seabed. Offshore wind turbines under special soil conditions with thick silt layer.

4. The tensioned mooring system and annular suction caisson used in the present invention have simple construction technology, convenient offshore installation, and are economical and reliable.

Description of drawings

Figure 1 is a side view of the offshore wind turbine monopile foundation according to the present invention.

Figure 2 is a top view of the offshore wind turbine monopile foundation according to the present invention.

Figure 3 is a schematic diagram of the seabed position installation of the offshore wind turbine monopile foundation according to the present invention.

Detailed ways

In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention will be further elaborated below in conjunction with specific implementation modes.

Referring to Figures 1, 2 and 3, an offshore wind turbine monopile foundation with a suction caisson and a tensioned mooring system according to the present invention includes a monopile foundation 1 on which a Suction caisson 2 and tensioned mooring system;

The main body of the suction caisson 2 is an annular structure, and an axial penetrating shaft hole is opened in the middle of the annular structure. The suction caisson 2 is sleeved on the single pile foundation 1 through the shaft hole, and the inner wall of the shaft hole The grouting connection section 3 is connected to the outer surface of the single pile foundation 1, and a number of reinforcing ribs 6 are provided between the inner and outer walls of the suction caisson 2;

The tensioned mooring system includes mooring points located on the monopile foundation 1 and at least two anchor foundations 5 arranged on the seabed around the monopile foundation 1. The anchor foundation 5 is connected to the monopile through the anchor line 4. The mooring points on foundation 1 are connected and tensioned.

The distance between the inner wall of the shaft hole and the outer surface of the single pile foundation 1 is 1.5 times the wall thickness of the single pile foundation 1 .

The reinforcing ribs 6 are distributed from the top of the suction caisson 2 to the bottom of the suction caisson 2. The distribution density of the reinforcing ribs 6 in the top 1/3 of the suction caisson 2 is greater than that of the reinforcing ribs in the bottom 2/3 of the suction caisson 2. 6 distribution density.

The suction caisson 2 has a negative pressure press-fitting assembly, which includes a negative pressure device and a water pumping hole arranged on the top. After the suction caisson 2 is loaded with negative pressure, 1/3 of the top of the suction caisson 2 is higher than the seabed.

One end of the anchor line 4 is connected to the mooring point on the single pile foundation 1, and the other end of the anchor line 4 is connected to the anchor foundation 5 in the seabed. The anchor line 4 is in a tensioned state, and the angle between the anchor line 4 and the horizontal plane is 30°. °-60°; the number of anchor lines 2 is an even number and is symmetrically and evenly arranged around the single pile foundation 1.

The anchoring foundation 5 includes suction anchors, suction penetration plate anchors, normal load-bearing anchors and dynamic penetration anchors.

The construction steps of the offshore wind turbine single pile foundation are as follows:

1) Place the suction caisson 2 on the seabed, and then pass the main body of the single pile foundation 1 through the shaft hole of the suction caisson 2;

2) Install the single pile foundation 1 to the specified depth, and complete the connection between the shaft hole of the suction caisson 2 and the outer surface of the single pile foundation 1 through the grouting process;

3) Install the suction caisson 2 to the design height through the negative pressure assembly of the suction caisson 2;

4) Arrange the anchor foundation 4 on the seabed around the monopile foundation 1, and connect and tighten the anchor foundation 5 with the mooring points on the monopile foundation 1 through the anchor lines 4.

This invention solves the problem of offshore problems by setting up an annular suction caisson foundation at the connection point between the single pile foundation and the seabed to increase the stiffness of the single pile foundation at the seabed, and controlling the horizontal displacement and dynamic response of the single pile foundation through the tensioning mooring system. The problem of insufficient bending resistance and horizontal bearing capacity of the wind turbine single pile foundation increases the stability of the single pile foundation and is suitable for seabed conditions where the soil strength of the shallow seabed is small or the silt layer is thick.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have other aspects. Various changes and modifications are possible, which fall within the scope of the claimed invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims (4)

1. An offshore wind turbine single pile foundation with a suction caisson and a tensioning mooring system, which comprises a single pile foundation (1), and is characterized in that the single pile foundation (1) is provided with the suction caisson (2) and the tensioning mooring system;

the main body of the suction caisson (2) is of an annular structure, an axial penetrating shaft hole is formed in the middle of the annular structure, the suction caisson (2) is sleeved on the single pile foundation (1) through the shaft hole, the inner wall of the shaft hole is connected with the outer surface of the single pile foundation (1) through a grouting connecting section (3), and a plurality of reinforcing rib plates (6) are arranged between the inner wall and the outer wall of the suction caisson (2);

the tensioning mooring system comprises a mooring line point positioned on the single pile foundation (1) and at least two anchoring foundations (5) arranged on the seabed around the single pile foundation (1), wherein the anchoring foundations (5) are connected with the mooring line point on the single pile foundation (1) through anchor lines (4) and tensioned;

one end of the anchor line (4) is connected with a mooring point on the single pile foundation (1), the other end of the anchor line (4) is connected with an anchor foundation (5) in the seabed, the anchor line (4) is in a tensioning state, and the angle between the anchor line (4) and the horizontal plane is 30-60 degrees; the number of anchor lines (2) is even and symmetrically and uniformly arranged around the single pile foundation (1);

the anchoring foundation (5) comprises a suction anchor, a suction penetration plate anchor, a normal bearing anchor and a power penetration anchor;

the reinforced rib plates (6) are distributed from the top of the suction caisson (2) to the bottom of the suction caisson (2), and the distribution density of the reinforced rib plates (6) at the 1/3 part of the top of the suction caisson (2) is larger than that of the reinforced rib plates (6) at the 2/3 part of the bottom of the suction caisson (2).

2. Offshore wind turbine mono-pile foundation with suction caisson and tensioning mooring system according to claim 1, characterized in that the inner wall of the shaft hole is 1.5 times the wall thickness of the mono-pile foundation (1) from the outer surface of the mono-pile foundation (1).

3. Offshore wind turbine mono-pile foundation with suction caisson and tensioning mooring system according to claim 1, characterized in that the suction caisson (2) has a negative pressure assembly comprising a negative pressure device and a water suction hole arranged at the top, and that after the suction caisson (2) has been negative pressure assembled 1/3 of the top of the suction caisson (2) is above the seabed.

4. An offshore wind turbine mono-pile foundation with suction caisson and tension mooring system according to any one of claims 1-3, characterized in that the construction steps of the offshore wind turbine mono-pile foundation are as follows:

1) Placing the suction caisson (2) on a seabed, and then enabling the main body of the single pile foundation (1) to penetrate through the shaft hole of the suction caisson (2);

2) Installing the single pile foundation (1) to a designated depth, and connecting the shaft hole of the suction caisson (2) with the outer surface of the single pile foundation (1) through a grouting process;

3) Installing the suction caisson (2) to the designed height through a negative pressure press-fitting assembly of the suction caisson (2);

4) An anchoring foundation (4) is arranged on the seabed around the single pile foundation (1), and the anchoring foundation (5) is connected and tensioned with a mooring line point on the single pile foundation (1) through an anchor line (4).