Gravity suction combined type anchoring foundation, installation method and installation evaluation method

Abstract

The invention relates to a gravity and suction combined type anchoring foundation, an installation method and an installation evaluation method.The combined anchoring foundation comprises a gravity anchor assembly and a suction anchor assembly; the gravity anchor assembly is used for being connected with an upper draught fan and providing a stable gravity foundation for the draught fan. The top of the suction anchor assembly is fixed to the bottom of the gravity anchor assembly, and the suction anchor assembly is used for penetrating into a seabed with the target depth. According to the anchoring foundation, the gravity anchor assembly is connected to the suction anchor assembly, and the load bearing capacity of the anchoring foundation in the vertical direction and the horizontal direction is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind power, and in particular to a gravity-suction composite anchoring foundation, an installation method and an installation evaluation method. Background Art

[0002] With the transformation of the global energy structure and the growing demand for clean energy, offshore wind energy, as an important renewable energy source, has received widespread attention for its development and utilization. However, the construction of offshore wind farms faces complex marine environments and engineering and technical challenges, especially the harsh environment of deep sea areas, which poses a severe test to the stability of wind turbine structures. As a key supporting structure, the reliability of the design and construction of the anchor foundation is directly related to the safety and economy of the entire wind farm. Gravity anchors and suction anchors are two commonly used anchor foundation types in the construction of offshore wind farms. Gravity anchors are widely used in geological conditions such as soft soil layers due to their simple structure and excellent pull-out performance, while suction anchors are widely used in sandy and soft clay seabeds due to their convenient construction and strong adaptability.

[0003] Although gravity anchors are applicable to a variety of soil conditions, they show good stability in soft soil layers. However, their pull-out bearing capacity in soft soil is limited, and as the bearing capacity requirements increase, the increase in foundation size and weight will lead to increased construction costs and difficulties. In addition, the scouring effect of gravity anchors in soft soil is more obvious, resulting in an increased risk of overturning, and foundation reinforcement and anti-scouring measures are required to improve their stability. Suction anchors have good horizontal bearing capacity, but their penetration depth and stability in soft soil are somewhat insufficient.

[0004] In the current existing technology, a single anchor foundation type is difficult to meet the requirements for comprehensive performance of the foundation in a complex marine environment. Therefore, it is urgent to develop a new type of composite anchor foundation. Summary of the invention

[0005] In response to the above problems, the first purpose of the present invention is to provide a gravity-suction composite anchoring foundation, which combines the characteristics of gravity anchor and suction anchor, and improves the load-bearing capacity of the anchoring foundation in both vertical and horizontal directions by connecting the gravity anchor assembly to the suction anchor assembly.

[0006] The second object of the present invention is to provide a method for installing a gravity-suction composite anchor foundation.

[0007] The third object of the present invention is to provide an installation evaluation method for a gravity-suction composite anchor foundation.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The gravity-suction composite anchoring foundation described in the present invention comprises a gravity anchor assembly and a suction anchor assembly; the gravity anchor assembly is used to be connected to the upper wind turbine and provide a stable gravity foundation for the wind turbine; the top of the suction anchor assembly is fixed to the bottom of the gravity anchor assembly and is used to penetrate into the seabed at a target depth.

[0010] The gravity-suction composite anchor foundation, preferably, the gravity anchor assembly includes: a steel trough, a reinforcement plate, a guide hole and a hole plate connector; the steel trough is a shell structure with openings at the top and bottom; a plurality of the reinforcement plates are arranged in the steel trough, and the two ends are respectively connected to the inner wall of the steel trough; the top of each reinforcement plate is provided with the guide hole, the guide hole is connected to the reinforcement plate through the hole plate connector, and the guide hole is used to connect to the fan foundation; concrete blocks are cast in the steel trough, and the concrete blocks are used to provide a stable gravity foundation for the fan.

[0011] The gravity-suction composite anchor foundation, preferably, the gravity anchor assembly also includes lifting ears, and the lifting ears are respectively arranged on the outer wall of the steel channel for lifting the composite anchor foundation.

[0012] The gravity-suction composite anchor foundation preferably has two lifting ears, and the lifting ears are at a set distance from the top of the steel trough.

[0013] The gravity-suction composite anchoring foundation, preferably, the suction anchor assembly comprises: a cylinder cover and a cylinder skirt; the cylinder cover is arranged at the bottom of the steel trough; the cylinder skirt is a cylindrical structure, the upper end of which is connected to the cylinder cover, and the lower end penetrates into the seabed at the target depth.

[0014] The gravity-suction composite anchor foundation is preferably provided with drainage holes on the top of the tube skirt.

[0015] The gravity-suction composite anchor foundation is preferably such that the outer diameter of the cross section of the tube skirt is D, and the outer diameter of the cross section of the steel trough is 1.5D-2D.

[0016] The present invention also provides a method for installing a gravity-suction composite anchor foundation, comprising the following steps:

[0017] On the shore, concrete slurry is injected into the steel groove of the medium gravity anchor assembly equipped with the reinforcement plate and the guide hole, and the guide hole is exposed, and the suction anchor assembly is connected with the gravity anchor assembly. After the gravity-suction composite anchor foundation is prefabricated as a whole, it is suspended to the transport ship by a steel cable;

[0018] The gravity-suction composite anchor foundation is transported to the designated location by a transport ship, and is slowly suspended to the top of the installation location by the crane of the installation ship. During the lowering process, seawater is allowed to be discharged through the drainage holes of the suction anchor assembly.

[0019] The gravity-suction composite anchor foundation is placed on the seabed, and combined with its own weight, the suction anchor assembly is penetrated into the seabed at a set penetration speed;

[0020] When the penetration is completed, the sling is separated from the foundation by an underwater robot, and a suction pump is used to pump water out through the drainage hole. A pressure difference is generated inside and outside the suction anchor assembly. Under the action of the pressure difference, the gravity-suction composite anchor foundation continues to penetrate into the seabed at the set penetration speed until the penetration is completed. The installation of the gravity-suction composite anchor foundation is completed.

[0021] The present invention also provides an installation evaluation method for a gravity-suction composite anchor foundation, comprising:

[0022] Installation requires overcoming the penetration resistance of the seabed to the cylinder wall structure of the suction anchor assembly;

[0023] The penetration resistance expression of the gravity suction composite anchor foundation during the penetration process is:

[0024] R=R inside +R outside +R tip

[0025] Where R is the total penetration resistance, R inside is the inner friction of the skirt, R outside is the outer friction of the skirt, R tip is the end resistance of the tube skirt;

[0026] R inside =απd1hs u

[0027] Where a is the friction coefficient between the suction anchor assembly and the soil, d1 is the inner diameter of the suction anchor assembly, h is the penetration depth of the bottom end of the suction anchor assembly, and s is u is the undrained shear strength;

[0028] R outside =απd2hs u

[0029] Where d2 is the outer diameter of the suction anchor assembly;

[0030] R tip =(γ′h+N c s u )(πdt)

[0031] Where γ' is the effective weight of the soil, Nc is the bearing capacity coefficient, d is (d1+d2) / 2, and t is the thickness of the tube skirt.

[0032] The present invention adopts the above technical solution, which has the following advantages:

[0033] (1) The composite anchor foundation of the present invention significantly improves the pull-out bearing capacity by combining the advantages of gravity anchors and suction anchors, while enhancing the stability of the structure, effectively solving the problems of insufficient bearing capacity and overturning risk of a single anchor foundation;

[0034] (2) The composite anchor foundation design of the present invention optimizes the structural layout, reduces the foundation size and weight that must be increased due to the increase in bearing capacity, thereby reducing construction costs and difficulty and improving construction efficiency;

[0035] (3) The composite anchor foundation design of the present invention improves the penetration depth and stability of the suction anchor in soft soil, so that the composite anchor foundation can better adapt to different seabed conditions and meet the engineering requirements of complex marine environments;

[0036] (4) The composite anchor foundation of the present invention adopts prefabricated molding and modular installation methods, which simplifies the installation process and performs automated installation through underwater robots, reducing manual underwater operations and improving construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Throughout the accompanying drawings, the same reference numerals are used to represent the same components. In the accompanying drawings:

[0038] Figure 1 It is a schematic diagram of the three-dimensional structure of the gravity anchor of the present invention;

[0039] Figure 2 yes Figure 1 Schematic diagram of the main structure;

[0040] Figure 3 yes Figure 1 A schematic diagram of a top view structure;

[0041] Figure 4 It is a three-dimensional structural schematic diagram of the gravity anchor after prefabrication of the present invention;

[0042] Figure 5 yes Figure 4 Schematic diagram of the main structure;

[0043] Figure 6 yes Figure 4 A schematic diagram of a top view structure;

[0044] Figure 7 It is a partially enlarged three-dimensional structural schematic diagram of the gravity anchor of the present invention;

[0045] Figure 8 yes Figure 7 Side view of

[0046] Fig. 9 It is a schematic diagram of the overall structure of the present invention;

[0047] Fig.10 It is a three-dimensional structural schematic diagram of the overall structure of the present invention;

[0048] Fig.11 The schematic diagram of the overall structure of the present invention after prefabrication;

[0049] Fig.12 This is a schematic diagram of the grouting prefabrication stage of the installation step 1 of the present invention;

[0050] Fig.13 This is a schematic diagram of the hoisting and sinking stage of the second installation step of the present invention;

[0051] Fig.14 This is a schematic diagram of the self-weight penetration stage of the third installation step of the present invention;

[0052] Fig.15 This is a schematic diagram of the suction penetration stage of the fourth installation step of the present invention;

[0053] Fig.16 This is a schematic diagram of the installation completion of the present invention;

[0054] Fig.17 It is a schematic diagram of the present invention in service.

[0055] The reference numerals in the figures are as follows:

[0056] 1- gravity anchor assembly; 1-1- steel channel; 1-2- lifting ear; 1-3- reinforcing plate; 1-4- cable guide hole; 1-5- hole plate connector; 1-6- concrete block; 2- suction anchor assembly; 2-1- cylinder cover; 2-2- cylinder skirt, 2-3- drainage hole. DETAILED DESCRIPTION

[0057] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0058] The present invention provides a gravity-suction composite anchor foundation, which combines the characteristics of a gravity anchor and a suction anchor, and improves the load bearing capacity of the anchor foundation in both vertical and horizontal directions by connecting a gravity anchor to the suction anchor.

[0059] like Fig. 9 , Fig.10 and Fig.11 As shown, the gravity-suction composite anchoring foundation provided by the present invention includes a gravity anchor assembly 1 and a suction anchor assembly 2; the gravity anchor assembly 1 is used to be connected to the upper wind turbine and provide a stable gravity foundation for the wind turbine; the top of the suction anchor assembly 2 is fixed to the bottom of the gravity anchor assembly 1 and is used to penetrate into the seabed at a target depth.

[0060] In the above embodiment, preferably, Figures 1 to 6 As shown, the gravity anchor assembly 1 includes: a steel channel 1-1, a reinforcing plate 1-3 (see Figure 8 ), navigation holes 1-4 and hole plate connectors 1-5 (see Figure 7 ); the steel trough 1-1 is a shell structure with openings at the top and bottom; a number of reinforcing plates 1-3 are arranged in the steel trough 1-1, and the two ends are respectively connected to the inner wall of the steel trough 1-1; a guide hole 1-4 is arranged on the top of each reinforcing plate 1-3, and the guide hole 1-4 is connected to the reinforcing plate 1-3 through a hole plate connector 1-5, and the guide hole 1-4 is used to connect to the fan foundation; concrete blocks 1-6 are cast in the steel trough 1-1, and the concrete blocks 1-6 are used to provide a stable gravity foundation for the fan.

[0061] In the above embodiment, preferably, the gravity anchor assembly 1 further includes lifting ears 1-2, which are respectively arranged on the outer wall of the steel channel 1-1 for lifting the composite anchor foundation.

[0062] In the above embodiment, preferably, there are two lifting ears 1-2, and the lifting ears are 0.1m away from the top of the steel trough.

[0063] In the above embodiment, preferably, Fig. 9 As shown, the suction anchor assembly 2 includes: a cylinder cover 2-1 and a cylinder skirt 2-2; the cylinder cover 2-1 is arranged at the bottom of the steel trough 1-1; the cylinder skirt 2-2 is a cylindrical structure, the upper end of which is connected to the cylinder cover 2-1, and the lower end is penetrated into the seabed at the target depth.

[0064] In the above embodiment, preferably, a drainage hole 2-3 is also provided on the top of the tube skirt 2-2. Thus, seawater can be discharged during the self-weight penetration of the foundation, and during the negative pressure penetration, water can be pumped in the tube by connecting to a negative pressure pump to cause a pressure difference between the inside and outside of the tube, so that the composite foundation can be further penetrated to the designed depth; after the negative pressure pumping is completed, underwater grouting can be carried out through the drainage hole to fill the gap between the tube cover and the seabed, so as to give full play to the bearing capacity of the foundation.

[0065] It should be noted that the diameter of the tube cover is generally 6-8 meters, and the thickness is generally 0.5 meters; the height of the tube skirt is generally not more than 10 meters when used in sandy seabeds, and generally not more than 20 meters when used in clay seabeds. The tube wall thickness of the tube skirt is generally 0.3-0.5 meters; the drainage hole is located at the top of the tube skirt and has a diameter of 0.2 meters.

[0066] In the above embodiment, preferably, the outer diameter of the cross section of the tube skirt 2-2 is D, and the outer diameter of the cross section of the steel groove 1-1 is 1.5D-2D.

[0067] like Figures 12 to 15 As shown, the present invention also provides a method for installing a gravity suction composite anchor foundation, comprising the following steps:

[0068] Step 1: On the shore, concrete slurry is injected into the steel groove of the medium gravity anchor assembly equipped with the reinforcement plate and the guide hole, and the guide hole is exposed, and the suction anchor assembly is connected with the gravity anchor assembly. After the gravity-suction composite anchor foundation is prefabricated as a whole, it is suspended to the transport ship by a steel cable;

[0069] Step 2: The gravity-suction composite anchoring foundation is transported to the designated location by a transport ship, and is slowly suspended to the top of the installation location by the crane of the installation ship. During the lowering process, seawater is allowed to be discharged through the drainage holes of the suction anchor assembly;

[0070] Step 3: Place the gravity-suction composite anchor foundation on the seabed, and use its own weight to make the suction anchor assembly penetrate into the seabed at the set penetration speed. The penetration speed should be controlled by the steel cable at this stage, and the penetration speed is generally 3m / min. A larger penetration speed will cause the foundation to cause local scouring of the sandy seabed, forming local gullies at the bottom of the foundation, and reducing the effective penetration depth of the foundation, affecting the in-situ bearing capacity of the foundation. A larger penetration speed will cause the foundation to cause greater disturbance to the surface soil of the clay seabed, affecting the bearing capacity of the foundation.

[0071] Step 4: After the penetration is completed, the sling is separated from the foundation by an underwater robot, and a suction pump is used to pump water out through the drainage hole. A pressure difference is generated inside and outside the suction anchor assembly. Under the action of the pressure difference, the gravity suction composite anchor foundation continues to penetrate into the seabed at the set penetration speed until the penetration is completed. The installation of the gravity suction composite anchor foundation is completed. Fig.16 This is a schematic diagram of the installation completion of the present invention. Fig.17 It is a schematic diagram of the present invention in service.

[0072] The present invention also provides an installation evaluation method for a gravity-suction composite anchor foundation, comprising:

[0073] Installation requires overcoming the penetration resistance of the seabed to the cylinder wall structure of the suction anchor assembly;

[0074] The penetration resistance expression of the gravity suction composite anchor foundation during the penetration process is:

[0075] R=R inside +R outside +R tip

[0076] Where R is the total penetration resistance, R inside is the inner friction of the skirt, R outside is the outer friction of the skirt, R tip is the end resistance of the tube skirt;

[0077] R inside =απd1hs u

[0078] Where a is the friction coefficient between the suction anchor assembly and the soil, d1 is the inner diameter of the suction anchor assembly, h is the penetration depth of the bottom end of the suction anchor assembly, and s is u is the undrained shear strength;

[0079] R outside =απd2hs u

[0080] Where d2 is the outer diameter of the suction anchor assembly;

[0081] R tip =(γ′h+N c s u )(πdt)

[0082] Where γ' is the effective weight of the soil, Nc is the bearing capacity coefficient, d is (d1+d2) / 2, and t is the thickness of the tube skirt.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gravity suction composite anchor foundation, characterized in that: It includes a gravity anchor assembly and a suction anchor assembly; The gravity anchor assembly is used to be connected to the upper wind turbine and provide a stable gravity foundation for the wind turbine; the top of the suction anchor assembly is fixed to the bottom of the gravity anchor assembly and is used to penetrate into the seabed at a target depth.

2. The gravity suction composite anchor foundation according to claim 1, characterized in that: The gravity anchor assembly includes: a steel channel, a reinforcing plate, a guide hole piece and a hole plate connecting piece; The steel trough is a shell structure with openings at the top and bottom; A plurality of reinforcing plates are arranged in the steel channel, and both ends are connected to the inner wall of the steel channel respectively; The top of each reinforcement plate is provided with the guide hole, the guide hole is connected to the reinforcement plate through a hole plate connector, and the guide hole is used to connect to the fan foundation; Concrete blocks are poured in the steel trough, and the concrete blocks are used to provide a stable gravity foundation for the fan.

3. The gravity suction composite anchor foundation according to claim 2 is characterized in that: The gravity anchor assembly also includes lifting ears, which are respectively arranged on the outer wall of the steel channel and are used for lifting the composite anchor foundation.

4. The gravity suction composite anchor foundation according to claim 3, characterized in that: There are two lifting ears, and a distance between the lifting ears and the top of the steel trough is set.

5. The gravity suction composite anchor foundation according to claim 2, characterized in that: The suction anchor assembly comprises: a cylinder cover and a cylinder skirt; The cylinder cover is arranged at the bottom of the steel trough; The tube skirt is a cylindrical structure, the upper end of which is connected to the tube cover, and the lower end penetrates into the seabed at the target depth.

6. The gravity suction composite anchor foundation according to claim 5, characterized in that: The top of the tube skirt is also provided with a drainage hole.

7. The gravity suction composite anchor foundation according to claim 6, characterized in that: The outer diameter of the cross section of the tube skirt is D, and the outer diameter of the cross section of the steel channel is 1.5D-2D.

8. An installation method of the gravity suction composite anchor foundation according to any one of claims 2 to 7, characterized in that: The steps include: On the shore, concrete slurry is injected into the steel groove of the medium gravity anchor assembly equipped with the reinforcement plate and the guide hole, and the guide hole is exposed, and the suction anchor assembly is connected with the gravity anchor assembly. After the gravity-suction composite anchor foundation is prefabricated as a whole, it is suspended to the transport ship by a steel cable; The gravity-suction composite anchor foundation is transported to the designated location by a transport ship, and is slowly suspended to the top of the installation location by the crane of the installation ship. During the lowering process, seawater is allowed to be discharged through the drainage holes of the suction anchor assembly. The gravity-suction composite anchor foundation is placed on the seabed, and combined with its own weight, the suction anchor assembly is penetrated into the seabed at a set penetration speed; When the penetration is completed, the sling is separated from the foundation by an underwater robot, and a suction pump is used to pump water out through the drainage hole. A pressure difference is generated inside and outside the suction anchor assembly. Under the action of the pressure difference, the gravity-suction composite anchor foundation continues to penetrate into the seabed at the set penetration speed until the penetration is completed. The installation of the gravity-suction composite anchor foundation is completed.

9. An installation evaluation method based on the gravity suction composite anchor foundation installation method according to claim 8, characterized in that: include: Installation requires overcoming the penetration resistance of the seabed to the cylinder wall structure of the suction anchor assembly; The penetration resistance expression of the gravity suction composite anchor foundation during the penetration process is: R=R inside +R outside +R tip Where R is the total penetration resistance, R inside is the inner friction of the skirt, R outside is the outer friction of the skirt, R tip is the end resistance of the tube skirt; R inside =απd1hs u Where a is the friction coefficient between the suction anchor assembly and the soil, d1 is the inner diameter of the suction anchor assembly, h is the penetration depth of the bottom end of the suction anchor assembly, and s is u is the undrained shear strength; R outside =απd2hs u Where d2 is the outer diameter of the suction anchor assembly; R tip =(γ′h+N c s u (pdt) Where γ' is the effective weight of the soil, Nc is the bearing capacity coefficient, d is (d1+d2) / 2, and t is the thickness of the tube skirt.

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