A pile-tube composite truss offshore wind turbine foundation and its construction technology

Abstract

The present invention discloses a pile-barrel composite truss offshore wind turbine foundation, which includes a truss structure, a suction cylinder and a pile foundation. The suction cylinder is connected to the bottom of the truss structure, and an embedded sleeve for installing the pile foundation is provided on the suction cylinder. The embedded sleeve is located inside the cylinder, on the edge of the cylinder or outside the cylinder of the suction cylinder. The pile-barrel composite truss offshore wind turbine foundation provided by the present invention can ensure that the structure of the offshore wind turbine foundation has higher stability and bearing capacity, can better withstand extreme loads such as typhoons, and has strong adaptability to the seabed; the present invention also provides a construction process for a pile-barrel composite truss offshore wind turbine foundation, which can more effectively ensure that the suction cylinder sinks to the seabed according to the designed depth.

Description

Technical Field

[0001] The present invention relates to the field of offshore wind power engineering, and in particular to a pile-tube composite truss type offshore wind turbine foundation and a construction process thereof. Background Art

[0002] As a renewable energy source, offshore wind power has been vigorously researched and promoted by countries around the world in recent years. The negative pressure cylinder (suction cylinder) is a large-diameter cylindrical thin-walled structure. As a form of anchoring and foundation, the negative pressure cylinder has been widely used in marine structure mooring systems, marine foundation platforms and marine wind turbine foundations. It has the advantages of simple assembly, high construction efficiency and low cost.

[0003] For example, a Chinese patent document with publication number CN109914460A discloses a new type of suction cylinder type combined structure wind power foundation suitable for shallow sea, which relates to the field of wind power generation technology. The system includes a central pile, a suction cylinder, a cylinder wall, a top cover, a compartment plate, steel stiffening ribs, a tower connection section and bolts. The suction cylinder is enclosed by a cylinder wall and a top cover, and three compartment plates are arranged in the cylinder to form a suction cylinder cavity. The cylinder wall, the top cover and the compartment plate are all made of double-layer steel plate concrete, and bolts are welded on the side where the steel plate contacts the concrete to strengthen the connection. The central pile adopts solid steel tube concrete or empty steel tube, and the pile top and pile side are firmly connected to the top cover and the compartment plate respectively. A tower connection section is arranged on the upper part of the top cover, and steel stiffening ribs are arranged along the circumferential direction, and the steel stiffening ribs are tightly connected to the top cover and the tower connection section. For example, a Chinese patent document with publication number CN109853609A discloses an offshore wind power combined foundation. The offshore wind power combined foundation includes a conductor frame, steel pipe piles, a suction cylinder and a steel cable. The offshore wind power combined foundation of the present invention is composed of a conductor frame, steel pipe piles, a suction cylinder and a steel cable. The conductor frame and the suction cylinder are connected by a steel cable. The steel cable can exert its high tensile strength to increase the lateral stiffness of the combined foundation. The conductor frame bears the vertical load. The horizontal load of the wind turbine and the wave flow force borne by the conductor frame are transmitted to the suction cylinder through the steel cable to be shared. Since the suction cylinder is dispersedly embedded in the surface soil and has a large contact area with the surface soil foundation, the horizontal force of the surface soil can be fully exerted, the horizontal bearing performance of the foundation piles is improved, the foundation anti-overturning ability is improved, and the pulling force borne by the main legs of the conductor frame is reduced, so that the distance between the main legs of the conductor frame and the cross-section of the rods can be reduced, and the foundation cost and construction difficulty can be reduced. The suction cylinder can be sunk by negative pressure, and the construction difficulty is small.

[0004] In the offshore wind power field, three or more suction cylinders are generally connected to a truss steel frame to form a suction cylinder truss wind turbine foundation. This foundation is limited by the seabed geological conditions of the installation area and is suitable for installation in areas with relatively stable geological structures. The installation process must ensure that multiple cylinders sink at the same time, and the suction cylinder foundation needs to control the suction cylinder to sink to the designed depth during the sinking process. During the sinking process, the verticality of the structure and the horizontality of the overall superstructure need to be accurately controlled. And as the water depth increases, soil plugs are likely to form in the cylinder, bulges, or even buckling, resulting in the suction cylinder not being able to sink completely to the designed depth at the same time, and it is difficult to ensure the horizontality of the structure. This is also the difficulty of the current suction cylinder truss foundation during use. Summary of the invention

[0005] The purpose of the present invention is to provide a pile-tube composite truss offshore wind turbine foundation, which can ensure that the structure of the offshore wind turbine foundation has higher stability and bearing capacity, is more resistant to extreme loads such as typhoons, and has strong adaptability to the seabed; the present invention also provides a construction process for a pile-tube composite truss offshore wind turbine foundation, which can more effectively ensure that the suction cylinder sinks to the seabed according to the designed depth.

[0006] The present invention provides the following technical solutions:

[0007] The pile-tube composite truss offshore wind turbine foundation comprises a truss structure, a suction tube and a pile foundation. The suction tube is connected to the bottom of the truss structure, and an embedded sleeve for installing the pile foundation is provided on the suction tube.

[0008] The embedded sleeve is located inside, on the edge of or outside the suction cylinder. Both ends of the embedded sleeve are open, and the position, length and diameter of the embedded sleeve are determined according to actual conditions. The embedded position of the sleeve should take into account the overall strength of the structure and facilitate the installation of the suction cylinder, etc. Generally, it should be as far away from the position of the pile leg as possible. The downward extension length of the sleeve is considered from the perspective of ensuring the sealing of the suction cylinder, and the lower end is usually higher than the lower end of the suction cylinder. The length of the upper end of the sleeve should be convenient for the pile hammer to perform piling construction.

[0009] A solidified grouting layer is provided between the embedded sleeve and the pile foundation. The pile foundation may be a steel pile or a pile foundation of other suitable materials and types. The connection and fixation between the embedded sleeve and the pile foundation may be strengthened by the grouting layer.

[0010] When the embedded sleeve is located in the tube and at the tube edge of the suction tube, a reinforcing member for supporting the suction tube and connecting the suction tube and the embedded sleeve is provided in the suction tube. The reinforcing member is usually made of reinforcing ribs made of steel plates, H-shaped steels, or T-shaped steels.

[0011] The top of the suction cylinder is provided with a pump interface for connecting a suction pump or a suction pipeline. The design of the pump interface can refer to the design of the general suction cylinder structure, and the interface position can be determined from the perspectives of ensuring the overall strength of the cylinder body and facilitating the suction cylinder pumping operation.

[0012] The truss structure includes a pipe frame structure for carrying a wind turbine and a tower, and the pipe frame includes a plurality of pipe frame legs. The plurality of pipe frame legs refer to the bottom connection form of the pipe frame structure being three legs, four legs, or multiple legs. The pipe frame legs correspond one to one with the suction cylinders.

[0013] The conductor frame leg is connected to the top of the suction tube through a reinforcing member. The reinforcing member is usually made of a steel plate, H-shaped steel, or T-shaped steel.

[0014] The number of the conductor frame legs is at least three.

[0015] The present invention also provides a construction process for a pile-tube composite truss offshore wind turbine foundation, the construction process comprising the following steps:

[0016] (1) The truss structure and the suction cylinder connected to the bottom of the truss structure are hoisted to the seabed, and after contacting the seabed, the suction cylinder penetrates into the seabed until the bottom of the embedded sleeve is immersed in the soil, thereby forming a closed space in the suction cylinder;

[0017] (2) Pumping the suction cylinder through a suction pump or suction pipeline to make the suction cylinder sink to the specified elevation. After reaching the specified elevation, shut down the suction pump and seal the pump interface through a cover plate or grouting measures to complete the installation of the suction cylinder;

[0018] (3) After the suction cylinder is installed, the pile foundation is inserted into the embedded sleeve. After the pile is sunk, grouting is poured into the gap between the pile foundation and the embedded sleeve.

[0019] In step (2), an underwater suction pump can be used to carry out pumping operations after being connected to a pump interface. According to actual conditions, one or more suction pumps can be placed at the top of each suction cylinder, and a centralized control system can be used to control the pressure of the suction pump to ensure that the cylinders of multiple suction cylinders sink evenly. An above-water suction system can also be used to connect the suction pipeline to the pump interface 6 at the top of each suction cylinder to operate the cylinder to sink to a specified elevation.

[0020] In step (2), when the suction cylinder does not sink to the specified elevation or does not meet the structural level requirement after the suction pump is pumped by the suction pump or the suction pipeline, a pile hammer is used to knock the embedded sleeve to complete the sinking and leveling operation.

[0021] In step (3), by grouting the gap between the pile foundation and the embedded sleeve, the connection strength between the pile foundation and the embedded sleeve can be ensured. The setting of the pile foundation can also increase the bearing capacity of the entire offshore wind turbine foundation.

[0022] The pile-tube composite truss offshore wind turbine foundation provided by the present invention mainly utilizes the friction between the outer side of the suction tube, the outer side of the embedded sleeve, the outer side of the steel pile and the soil as well as the pressure difference between the inside and outside of the suction tube to resist the external load borne by the structure during use.

[0023] The present invention provides a truss-type wind turbine foundation of a hybrid type of suction tube and pile foundation, and proposes a method and process for facilitating offshore construction. The offshore wind turbine foundation and construction process provided by the present invention can effectively ensure that the suction tube sinks to the seabed according to the designed depth; once the geology is strong or there is an impermeable layer, resulting in the inability to construct to the designed depth by self-weight and negative pressure, the embedded casing can be used to act on the embedded casing structure through the external force of the construction hammer to construct the overall structure to the designed depth; in order to improve the bearing capacity and long-term stability of the structure, the pile foundation can be inserted inside the embedded casing, and the pile foundation and the embedded casing can be connected by grouting. The pile tube composite truss offshore wind turbine foundation provided by the present invention can ensure that the foundation structure has higher stability and bearing capacity, can better withstand extreme loads such as typhoons, and has the advantages of strong adaptability to the seabed, easy installation, low cost, and reusability, and has broad application prospects.

[0024] Compared with the traditional suction tube foundation and pile foundation structure, the advantages and innovations of the pile tube composite truss foundation are as follows:

[0025] 1) Strong adaptability to the seabed: It can be used for sandy geology, sandy soil, clay multi-layer geology, and can also be used for construction with thick soft soil cover and weak bearing capacity;

[0026] 2) High foundation reliability: It combines the advantages of traditional steel piles and new suction tube foundations to provide sufficient bearing capacity;

[0027] 3) Convenient construction: The truss structure itself stands on the seabed, and no auxiliary platform or auxiliary structure is needed to stabilize the truss foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the structure of a pile-tube composite truss offshore wind turbine foundation provided in Example 1;

[0029] Figure 2 A schematic diagram of the structure of the suction cylinder and pile foundation provided in Example 1;

[0030] Figure 3 A schematic top view of the suction cylinder and pile foundation provided in Example 1;

[0031] Figure 4 A schematic diagram of the structure of a pile-tube composite truss offshore wind turbine foundation provided in Example 2;

[0032] Figure 5A schematic diagram of the structure of the suction cylinder and pile foundation provided in Example 2;

[0033] Figure 6 A schematic top view of the suction cylinder and pile foundation provided in Example 2;

[0034] Figure 7 A schematic diagram of the structure of a pile-tube composite truss offshore wind turbine foundation provided in Example 3;

[0035] Figure 8 A schematic diagram of the structure of the suction cylinder and pile foundation provided in Example 3;

[0036] Fig. 9 This is a top view schematic diagram of the suction cylinder and pile foundation provided in Example 3. DETAILED DESCRIPTION

[0037] To make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0038] Example 1

[0039] The pile tube composite truss type offshore wind power foundation structure provided in this embodiment is as follows Figure 1-3 As shown, it consists of two major parts: an upper truss structure 1 and a lower suction tube and pile foundation combination part.

[0040] The truss structure 1 includes: any pipe frame structure that can be used to carry a wind turbine and a tower, and the bottom connection form of the pipe frame is three pipe frame legs.

[0041] The structure of the combined part of the suction cylinder 3 and the pile foundation 4 includes: a cylindrical thin-walled suction cylinder 2 with an opening at the bottom, and the top of the suction cylinder 2 is connected to the conductor frame leg through a reinforcing member 7. An embedded sleeve 3 for installing the pile foundation 4 is provided in the suction cylinder 2, and the embedded sleeve 3 is connected to the suction cylinder 2 through a reinforcing member 8. The two ends of the embedded sleeve 3 are open, and the position, length and diameter of the embedded sleeve are determined according to actual conditions. A reinforcing member 8 is also provided inside the suction cylinder 2 to ensure the connection between the suction cylinder 2 itself and the suction cylinder 2 and the embedded sleeve 3. The pile foundation 4 can be driven into the seabed through the embedded sleeve 3 to increase the bearing capacity of the foundation structure. The pile foundation 4 is connected to the embedded sleeve 3 through a grouting layer 5. A pump interface 6 is provided at the top of the suction cylinder 3 for connecting an underwater suction pump.

[0042] Example 2

[0043] As provided in Example 1, the pile-tube composite truss offshore wind power foundation and Figure 4-6 , the difference is that an embedded sleeve 3 is provided at the edge of the suction cylinder 2. The cylinder edge refers to the tangency between the suction cylinder 2 and the embedded sleeve 3.

[0044] Example 3

[0045] As provided in Example 1, the pile-tube composite truss offshore wind power foundation and Figure 7-9 The difference is that an embedded sleeve 3 is provided outside the suction cylinder 2, and a reinforcing member connected to the embedded sleeve 3 is not required inside the suction cylinder 2.

[0046] The construction process of the pile-tube composite truss offshore wind turbine foundation provided in Examples 1-3 includes the following steps:

[0047] (1) The truss structure and the suction cylinder connected to the bottom of the truss structure are hoisted to the seabed, and after contacting the seabed, the suction cylinder penetrates into the seabed until the bottom of the embedded sleeve is immersed in the soil, thereby forming a closed space in the suction cylinder;

[0048] (2) Pumping the suction cylinder with an underwater suction pump to make the suction cylinder sink to a specified elevation. After reaching the specified elevation, shut down the suction pump and seal the pump interface with a cover plate or grouting measures to complete the installation of the suction cylinder. When the suction cylinder does not sink to the specified elevation or does not meet the structural level requirements after the suction cylinder is pumped with an underwater suction pump, use a pile hammer to knock the embedded sleeve to complete the sinking and leveling operation;

[0049] (3) After the suction cylinder is installed, the pile foundation is inserted into the embedded sleeve. After the pile is sunk, grouting is poured into the gap between the pile foundation and the embedded sleeve.

[0050] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction process for a pile-tube composite truss offshore wind turbine foundation, characterized in that: The pile-tube composite truss offshore wind turbine foundation comprises a truss structure, a suction tube and a pile foundation, wherein the suction tube is connected to the bottom of the truss structure, and an embedded sleeve for installing the pile foundation is provided on the suction tube; The embedded sleeve is located inside the suction cylinder, on the edge of the cylinder or outside the cylinder; When the embedded sleeve is located at the edge of the suction cylinder, a reinforcing member for supporting the suction cylinder and connecting the suction cylinder with the embedded sleeve is provided inside the suction cylinder; when the embedded sleeve is located outside the suction cylinder, the suction cylinder does not need to be provided with a reinforcing member connected with the embedded sleeve; The truss structure includes a pipe frame structure for carrying a wind turbine and a tower, and the pipe frame includes a plurality of pipe frame legs; the number of the pipe frame legs is at least three; The construction process of the pile-tube composite truss offshore wind turbine foundation comprises the following steps: (1) The truss structure and the suction cylinder connected to the bottom of the truss structure are hoisted to the seabed, and after contacting the seabed, they penetrate into the seabed until the bottom of the embedded sleeve is submerged in the soil, forming a closed space in the suction cylinder; (2) Pump water from the suction cylinder through a suction pump or suction pipeline to make the suction cylinder sink to the specified elevation. After reaching the specified elevation, shut down the suction pump and seal the pump interface through a cover plate or grouting measures to complete the installation of the suction cylinder; (3) After the suction cylinder is installed, the pile foundation is inserted into the embedded sleeve. After the pile is sunk, grouting is performed in the gap between the pile foundation and the embedded sleeve. In step (2), when the suction cylinder fails to sink to the specified elevation or does not meet the structural level requirement after the suction cylinder is pumped out by a suction pump or a suction pipeline, a pile hammer is used to hit the embedded sleeve to complete the sinking and leveling operation.

2. The construction process of the pile-tube composite truss offshore wind turbine foundation according to claim 1 is characterized in that: A cured grouting layer is provided between the embedding sleeve and the pile foundation.

3. The construction process of the pile-tube composite truss offshore wind turbine foundation according to claim 1 is characterized in that: A pump interface is provided at the top of the suction cylinder for connecting a suction pump or a suction pipeline.

4. The construction process of the pile-tube composite truss offshore wind turbine foundation according to claim 1 is characterized in that: The catheter frame leg is connected to the top end of the suction cylinder through a reinforcement member.

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