CN117702795A - Pile foundation capable of preventing anchor chain from being stretched and seabed groove from being formed and implementation method thereof - Google Patents

Abstract

The invention discloses a pile foundation that prevents anchor chains from stretching and seabed trenches from being formed, and an implementation method thereof. The pile foundation includes a pile body with a steel pipe pile structure, and a telescopic device is provided on the top of the pile body; the telescopic device includes Spring, limit rod, and bottom cover and top cover fixed on the upper end of the inner wall of the pile body; one end of the spring is fixed on the bottom cover, and the limit rod passes downward through the top cover and is fixedly connected to the other end of the spring; the bottom cover and the top cover The height between them is greater than the ultimate working length of the spring; the upper end of the limiting rod has a fixed ring for the anchor chain to pass through. The invention can significantly increase the bearing capacity reserve of the anchoring foundation, effectively slow down or avoid the formation of seabed trenches in front of the anchoring foundation, and greatly increase the service life of the anchoring foundation and the safety of the offshore floating platform to which it is anchored.

Description

A pile foundation to prevent the anchor chain from stretching and the formation of seabed trenches and its implementation method

Technical field

The invention relates to the technical field of marine foundation engineering, and in particular to a pile foundation that prevents anchor chains from stretching and the formation of seabed trenches and an implementation method thereof.

Background technique

Offshore mooring system is a technology that uses multiple mooring foundations and anchor chains to fix floating platforms or ships to the seabed. It can overcome the limitations of water depth and distance from the shore and improve the stability and safety of offshore floating platforms. Therefore, it is widely used in the fields of offshore oil and gas exploration and offshore wind power. However, during the long-term service of the anchorage foundation, the anchor chain will be repeatedly tightened under the load of wind, wave and current in bad weather. On the one hand, the tightened anchor chain will cause the anchorage foundation to bear a larger uplift load and reduce the anchorage foundation. safety; on the other hand, during service, the anchor chain will not only swing up and down, but also sway left and right. As the anchor chain is repeatedly tightened and cut into the seabed, obvious grooves will gradually form on the seabed in front of the foundation. The presence will change the failure mode of the anchorage foundation and greatly reduce the bearing capacity of the anchorage foundation. The existing design specifications do not consider the adverse effects of seabed trenches on the anchorage foundation, making it difficult to ensure the safety of the anchorage foundation in long-term service.

Contents of the invention

Purpose of the invention: The first purpose of the present invention is to provide a pile foundation that prevents the anchor chain on the anchorage foundation from stretching and the formation of seabed trenches; the second purpose of the present invention is to provide an implementation method of the pile foundation.

Technical solution: The pile foundation according to the present invention to prevent the anchor chain from stretching and the formation of seabed trenches includes a pile body, which is a steel pipe pile structure with a telescopic device on the top; the telescopic device includes a spring and a limit rod. And the bottom cover and top cover fixed on the upper end of the inner wall of the pile body; one end of the spring is fixed on the bottom cover, and the limit rod passes downward through the top cover and is fixedly connected to the other end of the spring; the height between the bottom cover and the top cover is greater than the spring The limit working length; the upper end of the limit rod has a fixed ring for the anchor chain to pass through.

In the present invention, the main function of the limiting rod is to transmit the vertical force to the spring on the one hand, and to limit the horizontal shaking of the anchor chain on the other hand. The main function of the top cover is to transmit the force that limits the horizontal shaking of the anchor chain to the pile foundation. The main function of the bottom cover is to transfer the tensile force of the spring to the pile foundation.

Furthermore, the depth of the pile body embedded in the soil is determined according to the load-bearing requirements, in which the vertical load-bearing capacity needs to be greater than the ultimate tensile force of the spring, and the horizontal load-bearing capacity needs to be able to limit the shaking of the anchor chain.

Further, the diameter of the pile body is between 0.5 and 2m.

Furthermore, the length of the limit rod should be such that when the spring reaches its ultimate working length, the height of the fixed ring is slightly greater than when the anchor chain is tightened.

Further, the bottom cover and the top cover are welded and connected to the inner wall of the pile body respectively; the connection between the spring, the bottom cover, and the limit rod is welded or bolted as needed.

Further, when the spring limit tension of a single pile foundation does not meet the bearing capacity requirements, multiple pile foundations are arranged side by side, and the lengths of the limiting rods on the multiple pile foundations are along the distance away from the anchorage foundation. direction increases in sequence.

Through the multiple pile foundations installed under the anchor chain in the anchorage section, on the one hand, the anchor chain is restricted from shaking left and right, effectively reducing the width of the seabed trench; on the other hand, when the trench expands to a certain extent, the first pile close to the anchorage foundation The foundation will bear the downward cutting force of the anchor chain and prevent further expansion of the trench.

Further, the length of each limiting rod is determined based on the angle formed by the anchor chain and the seabed when the anchor chain is tightened and the spacing between the limiting rods.

Further, the ultimate pulling force of the spring is determined according to the actual situation, and it needs to satisfy that the sum of the ultimate pulling forces of the springs of multiple pile foundations is greater than the upward component force when the anchor chain is tightened.

The implementation method of the pile foundation according to the present invention to prevent the anchor chain from stretching and the formation of seabed trenches includes: after the installation of the anchor foundation is completed, laying the pile foundation under the anchor chain until the depth of the pile foundation into the soil reaches After designing the requirements, insert the anchor chain of the implantation section into the fixed ring.

Further, when there are multiple pile foundations, the designed spacing is set below the anchor chain and the length of the limiting rod on each pile foundation gradually increases in the direction away from the anchoring foundation. A number of the pile foundations; when the depth of the plurality of pile foundations reaches the design requirements, the anchor chains of the anchoring sections are inserted into each fixed ring in turn.

Beneficial effects: Compared with the existing technology, the present invention has the following significant advantages:

The invention utilizes a spring combined with a limiting rod. Under the action of the spring, the limiting rod can automatically retract after being pulled up. At the same time, the limiting rod is not allowed to be completely pulled up, and has a high pull-out resistance and bearing capacity. The invention uses the pile foundation under the anchor chain in the anchorage section to limit the left and right shaking of the anchor chain and effectively reduce the width of the seabed trench. On the other hand, when the trench expands to a certain extent, the pile foundation close to the anchoring foundation will bear the burden. The downward cutting force of the anchor chain prevents further expansion of the trench. Therefore, the present invention can significantly increase the bearing capacity reserve of the anchoring foundation, effectively slow down or avoid the formation of seabed trenches in front of the anchoring foundation, and greatly increase the service life of the anchoring foundation and the safety of the offshore floating platform to which it is anchored.

Description of the drawings

Figure 1 is a schematic structural diagram of a pile foundation provided by an embodiment of the present application to prevent the anchor chain from stretching and the formation of seabed trenches;

Figure 2 is a schematic diagram of the ultimate working state of multiple pile foundations in the embodiment of the present application.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

The reference numbers in Figures 1 to 2 are as follows:

1. Pile body; 2. Telescopic device; 20. Bottom cover; 21. Spring; 22. Limiting rod; 23. Top cover: 24. Fixing ring; 25. Anchor chain; 26. Angle.

As shown in Figure 1, the embodiment of the present application provides a pile foundation that prevents the anchor chain from stretching and the formation of seabed trenches. The pile foundation includes a pile body 1. The pile body 1 is a steel pipe pile structure with a telescopic device on the top. 2. The diameter of the pile body 1 is between 0.5 and 2m, which is selected according to the difficulty of construction. The depth of the pile body 1 embedded in the soil is determined according to the load-bearing requirements. The vertical load-bearing capacity needs to be greater than the ultimate tensile force of the spring 21, and the horizontal load-bearing capacity needs to be able to limit the shaking of the anchor chain 25.

The telescopic device 2 includes a spring 21, a limiting rod 22, and a bottom cover 20 and a top cover 23 that are welded and fixed to the upper end of the inner wall of the pile body 1. One end of the spring 21 is welded and fixed on the bottom cover 20, the limiting rod 22 passes downward through the top cover 23, and the lower end is welded and connected to the other end of the spring 21. The height between the bottom cover 20 and the top cover 23 is greater than the ultimate working length of the spring 21 . The upper end of the limiting rod 22 has a fixed ring 24 of a steel circular ring structure for the anchor chain 25 to pass through. The length of the limit rod 22 should be such that when the spring 21 reaches its ultimate working length, the height of the fixed ring 24 is slightly greater than the height of the anchor chain 25 when it is tightened.

The ultimate pulling force of the spring 21 is determined according to the actual situation. It needs to satisfy that the sum of the ultimate pulling forces of the springs 21 of multiple pile foundations is greater than the upward component force when the anchor chain 25 is tightened. 2 , in this embodiment, three pile foundations are provided below the anchor chain 25 of the anchor foundation, and the lengths of the limiting rods 22 on the three pile foundations increase sequentially in the direction away from the anchor foundation. Specifically, the length of each limiting rod 22 is determined based on the angle 26 formed between the anchor chain 25 and the seabed when the anchor chain 25 is tightened, and the distance between the limiting rods 22. The point of connection to the floating platform and the depth from sea level to seabed are roughly determined by inverse trigonometric functions.

The embodiments of the present application also provide the implementation method of the pile foundation to prevent the anchor chain from stretching and the formation of seabed trenches, including:

With reference to Figure 2, after the installation of the anchor foundation is completed, 3 anchors are laid in sequence according to the set spacing below the anchor chain 25, and in a manner that the length of the limit rod 22 on each pile foundation gradually increases in the direction away from the anchor foundation. A pile foundation. When the soil penetration depth of the three pile foundations reaches the design requirements, the anchor chains 25 of the anchorage sections are inserted into each fixed ring 24 in sequence, and the installation is completed.

Claims (10)

1. The pile foundation for preventing the anchor chain from being stretched and the seabed groove from being formed comprises a pile body (1), and is characterized in that the pile body (1) is of a steel pipe pile structure, and a telescopic device (2) is arranged at the top of the pile body; the telescopic device (2) comprises a spring (21), a limiting rod (22), and a bottom cover (20) and a top cover (23) which are fixed at the upper end of the inner wall of the pile body (1); one end of the spring (21) is fixed on the bottom cover (20), and the limiting rod (22) downwards penetrates through the top cover (23) and is fixedly connected with the other end of the spring (21); the height between the bottom cover (20) and the top cover (23) is greater than the limit working length of the spring (21); the upper end of the limiting rod (22) is provided with a fixed ring (24) for the anchor chain (25) to pass through.

2. Pile foundation according to claim 1, characterized in that the depth of penetration of the pile body (1) is determined according to the bearing requirements, wherein the vertical bearing capacity is required to be greater than the limit tension of the springs (21), and the horizontal bearing capacity is required to be able to limit the shaking of the anchor chain (25).

3. Pile foundation according to claim 1, characterised in that the pile shaft (1) has a diameter of between 0.5 and 2 m.

4. Pile foundation according to claim 1, characterized in that the length of the stop lever (22) is such that, in the extreme working length of the spring (21), the height of the securing ring (24) is slightly greater than the height of the anchor chain (25) when tightened.

5. Pile foundation according to claim 1, characterized in that the bottom cover (20) and the top cover (23) are welded to the inner wall of the pile body (1), respectively; the spring (21) is connected with the bottom cover (20) and the limiting rod (22) by welding or bolts according to the requirements.

6. Pile foundation according to any one of claims 1-5, characterised in that when the spring limit tension of a single pile foundation does not meet the load-bearing capacity requirement, a plurality of pile foundations are arranged side by side, the length of the stop bars (22) on the pile foundations increasing in sequence in a direction away from the anchor foundation.

7. Pile foundation according to claim 6, characterized in that the length of each stop lever (22) is determined on the basis of the angle (26) formed with the seabed when the anchor chain (25) is tensioned and the spacing between the stop levers (22).

8. Pile foundation according to claim 6, characterized in that the limit tension of the springs (21) is determined according to the actual situation, the sum of the limit tensions of the springs (21) of a number of said pile foundations being to be met being greater than the upward force component of the tightening of the anchor chain (25).

9. A method of implementing a pile foundation for preventing anchor chain pull-up and seabed trench formation, comprising: pile foundation according to any one of claims 1 to 8 is laid under its anchor chain (25) after the installation of the anchoring foundation is completed, until the depth of penetration of the pile foundation into the soil has reached the design requirements, and the anchor chain (25) of the implantation section is threaded into the securing ring (24).

10. A method according to claim 9, wherein, when there are a plurality of pile foundations, a designed number of pile foundations are sequentially laid under the anchor chain (25) at a set interval in such a manner that the length of the limit lever (22) on each pile foundation gradually increases in a direction away from the anchor foundation; and after the depth of the pile foundations in soil reaches the design requirement, sequentially penetrating the anchor chains (25) of the implantation sections into each fixing ring (24).