Dried piles and methods for constructing driven piles

Abstract

To propose a driving pile that can be adjusted within the range of crane capacity by utilizing the buoyancy of a pile and that can reduce the labor and cost of construction, and a construction method for this driving pile.SOLUTION: A driving pile 2 to be driven into bottom of the water comprises a pile body 3 consisting of a hollow cylinder, a bag body 4 disposed inside the pile body 3, a fall-off prevention lid 5 provided on top of the pile body 3, an air supply pipe 6 connected to top of the bag body 4, and an exhaust pipe 7 connected to the top of the bag body 4. The bag body 4 expands due to gas pressed in through the air supply pipe 6, and contracts towards the fall-off prevention lid 5 side by exhausting gas from the exhaust pipe 7.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a driven pile for underwater construction and a method for constructing the driven pile.

Background Art

[0002] As a foundation for an offshore wind power facility, there is a monopile foundation that supports a wind turbine tower by a single pile provided underwater. In the monopile foundation, a driven pile provided by driving a ready-made pile underwater or an embedded pile in which a ready-made pile is embedded in an excavation hole formed underwater is used. As a method for constructing a ready-made pile, there is a case where a ready-made pile is suspended using a crane of a crane ship, the ready-made pile is set on a pile gripper provided on the crane ship, and construction is performed while controlling pile inclination and the like by the pile gripper. In such a method for constructing a ready-made pile, it is necessary to use a crane ship having sufficient lifting capacity for the ready-made pile. On the other hand, as the specifications of the wind turbine increase, the weight of the ready-made pile used for the monopile foundation also increases, and there is a possibility that a crane ship capable of lifting the ready-made pile cannot be secured. In addition, transportation of the heavier pile is also troublesome. Therefore, there is a case where a construction method is adopted in which a ready-made pile is towed while floating on water and erected at a predetermined position to reduce the burden required for transporting and erecting the pile. For example, the construction method described in Patent Document 1 is to transport a steel pipe pile by floating it on water with both ends of the steel pipe pile sealed by air bags. In the construction method of Patent Document 1, after towing the steel pipe pile to a predetermined position, while suspending both ends of the steel pipe pile with a wire or the like, the air in the air bag is deaerated to allow water to enter the inside of the steel pipe pile, and the steel pipe pile that has lost buoyancy is sunk while being erected. In the construction method of Patent Document 1, since the pile is erected by a crane in a state where the buoyancy of the pile is lost, the burden on the crane is large. In addition, since a plurality of cranes are used to support both ends of the pile respectively, there are concerns about complication of the work and increase in cost.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Patent Application Publication No. 50-156187 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention aims to propose a driven pile and a method for constructing such a driven pile that can be adjusted within the range of crane capacity by utilizing the buoyancy of the pile, and that reduces the labor and cost of construction. [Means for solving the problem]

[0005] The driving pile of the present invention, which solves the aforementioned problems, comprises a pile body made of a hollow cylindrical body, a bag body disposed inside the pile body, and the upper part of the pile body. only A lid is provided to prevent the bag from coming off, and the top of the bag body via the on / off valve A connected air supply pipe and the upper part of the bag via pressure regulating valve It is equipped with a connected exhaust pipe. The bag expands due to the gas injected through the air supply pipe and contracts toward the retaining lid side when the gas is released through the exhaust pipe. The construction method for driving a pile into the seabed comprises a pile transport step of towing the pile to a predetermined position while it is floating on the water, an erection step of raising the pile in the water by lifting the upper end of the pile, and a driving step of driving the pile into the seabed. In the pile transport step, gas is injected into the bag through the air supply pipe to inflate the bag inside the pile body, and in the erection step, the gas inside the bag is exhausted through the exhaust pipe, and water is drawn into the inside of the pile body from the lower end of the pile body. According to this method of constructing driven piles, when water is introduced into the interior from the lower end of the pile body during the erection of the driven pile, the bag body contracts toward the retaining lid side, reducing the buoyancy acting on the lower end of the driven pile. As a result, the lower end of the driven pile sinks into the water and the driven pile tilts. Therefore, the driven pile becomes easier to erect and the load on the crane can be minimized. Furthermore, when erecting the driven pile, only the upper end of the driven pile needs to be supported, making it possible to construct the pile with a single crane, thus reducing the labor and cost of construction.

[0006] Furthermore, if the bag folds into an accordion-like shape when contracted, it is possible to prevent the bag from contracting haphazardly, making it easier to attach and detach the bag and to reuse it for other driven piles. Furthermore, if a pair of trunnions are fixed to the upper side of the pile body, it becomes easier to attach wires for transporting and erecting the driven pile, and they also serve as the axis of rotation when erecting the driven pile, allowing the pile to be erected in a balanced manner. Furthermore, if a float for preventing rotation is attached to the side of the pile body during the pile transport process, the rotation of the driven pile (mainly around its central axis) can be suppressed when transporting a driven pile in a lying position, preventing twisting of the towing wire, etc. Furthermore, the system may include a floating storage step for storing the driven piles while they are floating on the water. Storing the driven piles on the water eliminates the need to provide land or separate vessels for storage. It also eliminates the effort required for transporting the piles to and from storage. In this case, if a cover material for preventing the attachment of aquatic organisms is attached to the underwater side of the pile body, the attachment of organisms to the driven piles can be suppressed. [Effects of the Invention]

[0007] According to the present invention, the driven pile and the method for constructing this driven pile make it possible to adjust the pile's height within the crane's capacity by utilizing its buoyancy, and also reduce the labor and cost of construction. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view showing a floating wind power generation facility according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a driven pile. [Figure 3] This flowchart shows the construction method for driven piles. [Figure 4] This is a side view showing the preparation process. [Figure 5] This is a side view showing the floating storage process. [Figure 6] This is a perspective view showing an example of a cover material. [Figure 7] This is a side view showing the pile transfer process. [Figure 8] This diagram shows the erection process, where (a) is a front view showing the situation during erection work, and (b) is a side view after erection. [Figure 9] This is a perspective view showing an example of installing a driven pile into a pile gripper, where (a) is during pile insertion and (b) is after the driven pile has been installed. [Figure 10] This is a cross-sectional view showing the driving process. [Modes for carrying out the invention]

[0009] This embodiment describes the construction of the foundation structure of the floating wind power generation facility 1. Figure 1 shows the floating wind power generation facility 1 of this embodiment. As shown in Figure 1, the floating wind power generation facility 1 of this embodiment consists of a so-called monopile foundation in which the support columns 12 of the wind turbine 11 are supported on pile foundations 13. The foundation structure (pile foundation 13) of the floating wind power generation facility 1 is formed by driving piles (driven piles 2) into the seabed GL (ground G).

[0010] Figure 2 shows the driven pile 2. As shown in Figure 2, the driven pile 2 comprises a pile body 3, a bag body 4, a cover to prevent detachment 5, an air supply pipe 6, and an exhaust pipe 7. The pile body 3 is made of a hollow cylinder (e.g., a steel pipe). A pair of trunnions 31, 31 are fixed to the side surface of the pile body 3. The pair of trunnions 31, 31 are arranged at positions facing each other across the pile body 3 above the center in the height direction. The upper part of the pile body 3 tapers towards the upper end. On the other hand, the other parts of the pile body 3 have the same diameter.

[0011] The bag body 4 is disposed inside the pile body 3. An air supply pipe 6 and an exhaust pipe 7 are connected to the bag body 4. The bag body 4 expands by the gas press-fitted from the air supply pipe 6 and contracts by exhausting from the exhaust pipe 7. The bag body 4 is, for example, a cylindrical member made of a so-called highly airtight sheet of chemical fiber. The outer diameter of the bag body 4 when expanded is not less than the inner diameter of the pile body 3. Also, the bag body 4 is foldable and is folded in a bellows shape when contracted. The upper end of the bag body 4 is in close contact with the anti-drop lid 5. The anti-drop lid 5 is provided at the upper part of the pile body 3. In this embodiment, the anti-drop lid 5 is fixed inside the pile body 3 (such as by attaching a watertight bolt with a water-stopping function). A through hole through which the air supply pipe 6 or the exhaust pipe 7 can be inserted is formed in the anti-drop lid 5.

[0012] The air supply pipe 6 is connected to the upper part of the bag body 4 via an inlet valve 61. The exhaust pipe 7 is connected to the upper part of the bag body 4 via an outlet valve 71. The inlet valve 61 is an on-off valve. The outlet valve 71 of this embodiment uses a so-called relief valve (pressure regulating valve) that opens and exhausts when the pressure (air pressure) inside the bag body 4 exceeds the allowable pressure.

[0013] Hereinafter, the construction method of the driven pile 2 will be described. The procedure of the construction method of the driven pile 2 is shown in FIG. 3. As shown in FIG. 3, the construction method of the driven pile 2 of this embodiment includes a preparation step S1, a water storage step S2, a pile transfer step S3, an erection step S4, and a driving step S5. In preparation step S1, the driven pile 2 is transported to a designated storage location via barges Bs. Figure 4 shows preparation step S1. As shown in Figure 4, the driven pile 2 is unloaded from barges Bs onto the water using a crane ship or the like. At this time, with the exhaust pipe outlet valve 71 shielded, gas is injected into the bag body 4 via the air supply pipe 6 to inflate the bag body 4 inside the pile body 3. Once the bag body 4 is inflated, the inlet valve 61 is shielded to prevent the gas inside the bag body 4 from leaking out.

[0014] The floating storage process S2 is the process of storing the driven piles 2 while floating on the water. Figure 5 shows the floating storage process S2. The driven piles 2, which have been unloaded onto the water, are moored while floating on the water, as shown in Figure 5. At this time, the driven piles 2 are moored using multiple mooring lines (wires, ropes, etc.) R, one end of which is fixed to the seabed. In this embodiment, one end of the mooring line R is fixed to the seabed via a sinker block SB provided on the seabed. A light buoy LB is attached to the sinker block SB. Furthermore, a buoy BU is attached to the mooring line R to prevent the mooring line R from sinking. Furthermore, a cover material 21 to prevent the attachment of aquatic organisms is attached in advance to the side of the driven pile 2 that will be submerged in water. Figure 6 shows the cover material 21. As shown in Figure 6, the cover material 21 consists of a plate material with a circular arc cross-section (half-cylindrical shape). The radius of the arc of the cover material 21 is the same as the outer diameter of the pile body 3, and it will fit snugly when attached to the side of the pile body 3. The method of fixing the cover material 21 is not limited; for example, it can be glued.

[0015] In pile transfer process S3, the driven pile 2 is towed from the storage location to the construction site while floating on the water. At this time, the expansion of the bag body 4 is maintained. Figure 7 shows pile transfer process S3. The driven pile 2 is towed to the construction site with a wire W extending from the towing vessel Bt attached to a pair of trunnions 31, 31. At this time, multiple anti-rotation floats 32, 32, ... are attached to the side of the pile body 3 to suppress the rotation of the driven pile 2 during towing (mainly rotation around the central axis) and prevent twisting of the towing wire W. Multiple anti-rotation floats 32, 32, ... are connected to the pile body 3 by ropes and are provided continuously along the side of the pile body 3. The anti-rotation float 33 is fixed to the pile body 3 via a metal band or magnet. A saddle pipe is installed between the tugboat Bt and the wire W to prevent the wire W from twisting.

[0016] In the erection process S4, the driven pile 2 is erected underwater. Figure 8 shows the erection process S4. The driven pile 2 is erected by lifting the wire W (upper side of the pile body 3) attached to a pair of trunnions 31, 31, as shown in Figure 8(a). In addition, in the erection process S4, some of the gas inside the bag body 4 is exhausted through the exhaust pipe 7. This allows water to be drawn into the pile body 3 from the lower end, and the bag body 4 shrinks towards the upper part of the pile body 3 (the side with the anti-loosening cover 5) due to the water pressure. As a result, the lower side of the pile body 3 becomes heavier than the upper side due to the reduced buoyancy, causing the pile body 3 to tilt, which makes it easier to erect the pile body 3. The amount of exhaust from the bag body 4 (the amount of water flowing into the pile body 3) is adjusted by the outlet valve 71. The erected driven pile 2 is set in the pile gripper PG of the crane ship Bc, as shown in Figure 8(b). Figure 9 shows the pile gripper PG. The pile gripper PG in this embodiment is openable and closable. Therefore, as shown in Figure 9(a), the erected driven pile 2 is inserted into the pile gripper PG by moving it horizontally, and as shown in Figure 9(b), the pile gripper PG is closed, allowing the driven pile 2 to be set in the pile gripper PG without having to lift it higher than the pile gripper PG.

[0017] In the driving process S5, the driving pile 2 is driven into the seabed GL. Figure 10 shows the driving process. With the lower end of the driving pile 2 resting (contacting) the seabed GL, the gas inside the bag 4 is exhausted through the exhaust pipe 7, and as shown in Figure 10, the lower end of the pile body 3 is inserted into the ground G (surface layer) by the weight of the driving pile 2. After that, if necessary, the driving pile 2 is driven in until the lower end reaches a predetermined depth by applying vertical vibration or impact or rotating it around the pile axis. Once the driving of the driving pile 2 is complete, the anti-loosening cover 5 and the bag 4 are removed from the upper end of the pile body 3.

[0018] According to the driving pile 2 and the method for constructing the driving pile 2 of this embodiment, by injecting gas into the bag 4 inside the driving pile 2, the apparent weight of the driving pile 2 can be reduced. Therefore, even if the weight of the driving pile 2 exceeds the lifting capacity of the crane, it is possible to erect it using buoyancy. Furthermore, when the driven pile 2 is erected, water flows into the interior from the lower end, causing the bag body 4 to contract toward the anti-slip lid 5. This reduces the buoyancy acting on the lower end of the driven pile 2, causing the lower end of the driven pile 2 to sink into the water and tilt. As a result, the driven pile 2 becomes easier to erect and can be adjusted within the crane's capacity. Furthermore, in the erection process S4, by adjusting the exhaust volume from the bag body 4 to control the apparent weight of the driven pile 2, it is possible to maintain balance when erecting the driven pile 2, thus allowing adjustment within the crane's capacity.

[0019] Furthermore, since a pair of trunnions 31, 31 are fixed to the upper side of the pile body 3, it is easy to attach wires used for transporting and erecting the driven pile 3. Also, since it serves as the axis of rotation when erecting the driven pile 2, the driven pile 2 can be erected in a balanced manner. Furthermore, since the driven pile 2 can float on water due to its buoyancy, it can be towed to a predetermined location while floating on the water, and its position can be adjusted within the crane's capacity. This, in turn, reduces the load on the towing vessel. Moreover, once moved to the predetermined location, no transshipment work is required. In addition, there is no limit to the number of piles that can be stored. Furthermore, since the piles can be transported one at a time, there is no need to load them onto a crane ship for transport. Therefore, there is no need to move the crane ship, which is the work vessel, for the purpose of transporting the piles, making it possible to shorten the construction period (construction cycle). Furthermore, since the driven piles 2 are stored floating on the water, there is no need to secure storage barges or land, which reduces costs. Because a cover material to prevent aquatic organisms from attaching is attached to the underwater side of the pile body 3, it is possible to suppress the attachment of organisms to the driven piles 2. Furthermore, in the pile transport process, by attaching anti-rotation floats 32 to the sides of the pile body 3, the rotation of the driven pile 2 (mainly around its central axis) is suppressed when transporting the driven pile 2 in a lying position, preventing twisting of the towing wire, etc. Furthermore, since the bag body 4 folds into an accordion shape when contracted, it is possible to prevent the bag body 4 from contracting in an uncontrolled manner. Because the accordion-shaped folded bag body 4 can be easily attached to and detached from the pile body 3, it can be easily reused for other driven piles.

[0020] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention. In the above embodiment, the case in which the driven pile 2 is used as the pile foundation 13 of the floating wind power generation facility 1 was described, but the structure supported by the driven pile 2 is not limited. Furthermore, the shape of the pile body 3 is not limited. Also, the upper end of the pile body 3 does not necessarily need to be reduced in diameter. Furthermore, although the embodiment described the case in which valves are provided in the air supply pipe 6 and the exhaust pipe 7, check valves or occluding caps may be provided in place of valves in the air supply pipe 6 and the exhaust pipe 7. Furthermore, although the above embodiment described a case in which a relief valve is installed in the exhaust pipe 7, the type of valve installed in the exhaust pipe 7 is not limited. [Explanation of Symbols]

[0021] 1. Floating wind power generation facility 2 Drive pile 21 Cover material 3. Main pile 31 Trunnions 4 Bag body 5. Anti-slip lid 6. Air tube 61 Inlet valve 7 Exhaust pipe 71 Outlet valve G Ground GL underwater H drilled hole

Claims

1. These are piles driven into the seabed. The pile body consists of a hollow cylindrical body, A bag-shaped body is disposed inside the pile body, A cover to prevent the pile from coming loose is provided only at the top of the pile body, An air supply pipe connected to the upper part of the bag body via an on / off valve, The bag body is equipped with an exhaust pipe connected to the upper part via a pressure regulating valve, A driving pile characterized in that the bag expands due to gas injected through the air supply pipe and contracts toward the anti-loosening lid side when the gas is exhausted through the exhaust pipe.

2. The driving pile according to claim 1, characterized in that the bag body folds into an accordion shape when contracted.

3. The driven pile according to claim 1, characterized in that a pair of trunnions are fixed to the upper side surface of the pile body.

4. A method for constructing driven piles, wherein the driven piles are driven into the seabed, The aforementioned driven pile comprises a pile body made of a hollow cylindrical body, a bag body disposed inside the pile body, a cover to prevent detachment provided at the top of the pile body, an air supply pipe connected to the top of the bag body, and an exhaust pipe connected to the top of the bag body. The bag expands due to the gas injected through the air supply pipe and contracts toward the anti-slip lid side when the gas is released through the exhaust pipe. A pile transport process in which the aforementioned driven pile is towed to a predetermined position while floating on the water, The erection process involves lifting the upper end of the driven pile to erect it underwater, The system includes a driving step of driving the aforementioned piles into the seabed, In the pile transfer process, gas is injected into the bag through the air supply pipe to expand the bag inside the pile body. A method for constructing driven piles, characterized in that, in the erection process, the gas inside the bag is exhausted through the exhaust pipe, and water is drawn into the pile body from the lower end of the pile body.

5. The method for constructing a driven pile according to claim 4, characterized in that, in the pile transport step, a float for preventing rotation is attached to the side surface of the pile body.

6. The method for constructing a driven pile according to claim 4, further comprising a water storage step of storing the driven pile while floating on the water.

7. The method for constructing a driven pile according to claim 6, characterized in that, in the above-water storage step, a cover material for preventing the attachment of aquatic organisms is attached to the underwater side surface of the pile body.

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