JP2023139586A - Reinforcement structure and reinforcement method for cylindrical body for underwater installation - Google Patents

Abstract

To provide a reinforcement structure of underwater installation cylindrical body capable of being easily constructed and suitably reinforcing a cylindrical body such as a steel pipe pile for supporting mono-pile foundations, piers, and the like, and a reinforcement method.SOLUTION: A reinforcement structure of an underwater installation cylindrical body 3 includes a reinforcement cylindrical body 7 that is placed outside the underwater installation cylindrical body 3. The reinforcement cylindrical body 7 includes: an inner tube 8 placed along the outer periphery of the underwater installation cylindrical body 3; an outer tube 9 placed outside the inner tube; and an upper lid 11 that closes the upper surface of a compartment 10 formed between the inner tube 8 and the outer tube 9. The reinforcement cylindrical body 7 is designed to penetrate underwater ground 1 by depressurizing the compartment 11.SELECTED DRAWING: Figure 2

Description

The present invention relates to a reinforcement structure and method for reinforcing a cylindrical body for underwater installation, which reinforces a cylindrical body used for the foundation of an offshore wind power generation facility, a support pile of a pile support structure, or the like.

BACKGROUND OF THE INVENTION As a ground-mounted offshore wind power generation system, one in which wind turbine equipment and the like are supported on a monopile foundation made of a cylindrical body penetrated into the underwater ground is known. Furthermore, in pile support structures such as piers, structures in which a superstructure is supported by a substructure foundation made of a cylindrical body (steel pipe pile) penetrated into the underwater ground are known.

The method of installing this type of cylindrical body involves transporting the cylindrical body, such as a monopile, manufactured in a factory or production yard on land to a base port, and then transporting it to a base port on an elevating work vessel (hereinafter referred to as a SEP vessel). ) is used to load the cylindrical body onto a SEP ship, and the SEP ship transports the cylindrical body by sea to the installation sea area and then installs it (for example, see Patent Document 1).

Specifically, after transporting the cylindrical body by sea to the installation area using a SEP ship, the legs of the SEP ship are lowered to the bottom of the installation area, and the SEP ship supported by the legs is raised above the water. to keep the SEP ship in a stable state against waves, etc.

Next, using the SEP ship's crane, the cylindrical body such as a monopile loaded on the SEP ship is hoisted up and erected, and in this state, it is lowered to the underwater ground and allowed to land on the bottom.

Then, the head of the cylindrical body that has landed on the bottom of the water is driven in with a hammer or the like, and the cylindrical body is installed by penetrating the bottom of the water.

On the other hand, a suction type foundation is also known as an underwater foundation structure for a structure such as a fixed-type offshore wind power generation facility (for example, see Patent Document 2).

This suction type foundation is equipped with a top plate connected to the superstructure and a skirt part extending downward from the periphery of the top plate. By discharging the water in the closed skirt section through the drain pipe, a suction load acts together with the weight of the entire structure, causing the skirt section to penetrate into the submerged ground.

JP2014-227966A JP2020-023838A

However, in the cylindrical body that constitutes the monopile foundation that supports the wind turbine of the conventional offshore wind power generation equipment as described above, and the cylindrical body that supports the superstructure (hereinafter referred to as the cylindrical body for underwater installation), the lower part is at the bottom of the water. It penetrates and is supported by the ground, and is subject to large bending moments and shearing forces in the event of an earthquake, so to ensure safety, a cylindrical structure for installation on the bottom of the water is prepared in advance to withstand the bending moments and shearing forces. It is necessary to increase the outer diameter and wall thickness of the body.

In addition, in recent years, as wind turbines and other wind power generators and underwater and floating structures such as piers have become larger and their installation locations have become deeper, the cylindrical bodies and superstructures that make up the monopile foundations that support wind turbines have become smaller. The supporting cylindrical body has also become heavier and longer.

Therefore, when constructing a cylindrical body for installation on the bottom, which has a large diameter and a large weight, using conventional technology alone, the crane of the procured SEP ship lacked the lifting capacity, and it was difficult to load the cylindrical body onto the ship's hull. It may be difficult to erect the cylindrical body.

In that case, it is necessary to separately arrange a large hoist ship with a crane that has a higher lifting capacity than the SEP ship's crane, which increases the cost, makes it complicated to adjust the work process, and makes the work more extensive. There were other problems.

Furthermore, in recent years, standards for earthquake resistance and the like have tended to become stricter, and there is also the problem that there is no established method for reinforcing existing cylindrical bodies for underwater installation if they do not meet these standards.

On the other hand, with conventional suction type foundations, in order to ensure safety as a foundation, it is necessary to penetrate to a deep depth to resist bending moments and shear forces. There was a risk that construction would be difficult due to such factors.

In view of these conventional problems, the present invention aims to suitably reinforce cylindrical bodies such as steel pipe piles that support monopile foundations, piers, etc., and to provide reinforcement for cylindrical bodies for underwater installation that can be easily constructed. This was done for the purpose of providing a structure and reinforcement method.

A feature of the invention as set forth in claim 1 for solving the above-mentioned conventional problems is a reinforcing structure for a cylindrical body for underwater installation, which is erected on the underwater ground while penetrating into the underwater ground. The reinforcing cylindrical body is provided with a reinforcing cylindrical body disposed outside the cylindrical body for underwater bottom installation, and the reinforcing cylindrical body includes an inner pipe disposed along the outer periphery of the cylindrical body for underwater bottom installation; an outer tube disposed outside the inner tube; and an upper lid that closes an upper surface of a compartment formed between the inner tube and the outer tube; The reason is that it is designed to penetrate into the ground.

A feature of the invention according to claim 2 is that, in addition to the structure of claim 1, the reinforcing cylindrical body includes a plurality of reinforcing ribs connecting the inner tube and the outer tube at intervals in the circumferential direction. The reason is that it is equipped with the following.

A feature of the invention according to claim 3 is that, in addition to the configuration of claim 2, the reinforcing rib is formed in a plate shape that separates the compartment in the circumferential direction, and has an insertion hole penetrating in the thickness direction. It is in the fact that

The feature of the invention according to claim 4 is that, in addition to the configuration according to any one of claims 1 to 3, the reinforcing cylindrical body has a rigidity change suppressing member at the upper part that has lower bending rigidity than the reinforcing cylindrical body. The reason lies in the fact that it is equipped with parts.

A feature of the invention according to claim 5 is that, in addition to the structure according to any one of claims 1 to 4, the reinforcing cylindrical body is constituted by a plurality of divided cylindrical bodies divided in a longitudinal section. be.

A feature of the invention described in claim 6 is that, in addition to the configuration of any one of claims 1 to 5, the reinforcing cylindrical body is provided with a drain pipe that penetrates the upper lid and communicates with the compartment. It is in the fact that

A feature of the invention according to claim 7 is that, in addition to the configuration according to any one of claims 1 to 6, a filler is filled in a gap between the inner pipe and the outer circumferential surface of the cylindrical body for installation on the bottom of the water. There is a particular thing.

The feature of the invention according to claim 8 is a method for reinforcing a cylindrical body for underwater bottom installation, which is erected on the underwater bottom ground in a state of penetrating the underwater bottom ground, the outer periphery of the cylindrical body for underwater bottom installation being an inner tube disposed along the inner tube, an outer tube disposed outside the inner tube, and an upper lid closing an upper surface of a compartment formed between the inner tube and the outer tube. Using a reinforcing cylindrical body of The purpose of the present invention is to penetrate the reinforcing cylindrical body into the underwater ground.

In addition to the structure of claim 8, a feature of the invention according to claim 9 is that the reinforcing cylindrical body is divided into a plurality of divided cylindrical bodies divided in longitudinal section, and each divided cylindrical body is separated from the underwater ground. At the top, the parts are joined along the outer peripheral surface of the cylindrical body for installation on the bottom of the water.

The feature of the invention according to claim 10 is that, in addition to the configuration of claim 8 or 9, after the reinforcing cylindrical body penetrates into the underwater ground, the inner pipe and the underwater bottom installation cylindrical body are connected to each other. The purpose is to remove the earth and sand between them to form a gap, and then fill the gap with a filler.

The feature of the invention according to claim 11 is that, in addition to the configuration according to any one of claims 8 to 10, the shear force and bending moment acting on the cylindrical body for installation on the underwater bottom are analyzed and obtained for each depth. The purpose is to set the penetration length of the reinforcing cylindrical body based on the analysis results.

The feature of the invention according to claim 12 is that, in addition to the structure according to any one of claims 8 to 11, before the reinforcing cylindrical body penetrates into the underwater ground, the upper outer periphery of the reinforcing cylindrical body is The purpose is to attach scour prevention members to the area.

The reinforcing structure for the cylindrical body for installation on the water bottom according to the present invention has the structure of claim 1, so that even under conditions where the bending moment and shear force acting during an earthquake become large, the cylindrical body for installation on the water bottom can be reinforced. Safety can be ensured without increasing the diameter or wall thickness.

Moreover, in the present invention, by providing the configurations of claims 2 and 3, the strength of the reinforcing cylindrical body having a hollow structure can be ensured.

Moreover, in the present invention, by having the structure of claim 4, the bending rigidity caused in the cylindrical body for underwater bottom installation due to the difference in outer diameter or wall thickness between the cylindrical body for underwater bottom and the reinforcing cylindrical body can be reduced. Rapid changes can be suppressed.

In addition, in the present invention, by having the structure of claim 5, the reinforcing cylindrical body can be reliably constructed after the cylindrical body for underwater bottom installation is cast, and the reinforcing cylindrical body can be reliably installed on the existing cylindrical body for underwater bottom installation. It can also be used for reinforcement.

Further, in the present invention, by providing the structure of claim 6, water in the reinforcing cylindrical body can be discharged and negative pressure can be generated.

Moreover, in the present invention, by providing the structure of claim 7, the cylindrical body for installation on the bottom of the water and the cylindrical body for reinforcement can be integrated.

The method for reinforcing a cylindrical body for installation on the underwater bottom according to the present invention is provided with the structure of claim 8, so that even under conditions where the bending moment and shear force acting during an earthquake become large, the cylindrical body for installation on the underwater bottom can be reinforced. Safety can be ensured without increasing the diameter or wall thickness.

Further, in the present invention, by having the structure of claim 9, the reinforcing cylindrical body can be reliably constructed after the cylindrical body for underwater bottom installation is cast, and the reinforcing cylindrical body can be reliably installed on the existing cylindrical body for underwater bottom installation It can also be used for reinforcement.

Further, in the present invention, by having the structure of claim 10, a gap is reliably formed between the cylindrical body for underwater installation and the reinforcing cylindrical body, and by filling the gap with a filler, the underwater installation is carried out. The cylindrical body and the reinforcing cylindrical body can be integrated.

Further, in the present invention, by providing the structure of claim 11, it is possible to reliably reinforce the portions that are largely affected by bending moments and shear forces, and there is no need to make the reinforcing cylindrical body unnecessarily long. .

Moreover, in the present invention, by providing the configuration of claim 12, the work can be performed efficiently without the need for constructing the scour prevention member in a subsequent process.

FIG. 2 is a front view showing an embodiment of a reinforcing structure for a cylindrical body for installation on the bottom of water according to the present invention. (a) is a cross-sectional view taken along the line AA showing the same reinforced portion as above, and (b) is an enlarged vertical cross-sectional view of the same portion. (a) is a front view showing the divided cylindrical body constituting the same reinforcing cylindrical body as above, (b) is the same top view, (c) is the same bottom view, and (d) is the same as in FIG. 3(b). It is a sectional view taken along the line B-B. It is a graph which shows the result of measuring the bending moment and shear force of the structure using the cylindrical body for underwater installation same as the above. (a) is a plan view showing the state of the joining work of the divided cylindrical bodies constituting the reinforcing cylindrical body in the method for reinforcing a cylindrical body for underwater installation according to the present invention, and (b) is a side view of the same. (a) is a plan view showing a state in which the reinforcing cylindrical body is joined to the bottom, and (b) is a partially cutaway sectional view of the same. FIG. 3 is a partially cutaway sectional view showing a state in which drainage has started in the reinforcing cylindrical body same as above. It is a partially broken sectional view showing the state of the penetration work of the reinforcing cylindrical body same as the above. (a) is a sectional view taken along the line AA showing the reinforcing cylindrical body as described above penetrated into the underwater ground, and (b) is a partially broken sectional view of the same. (a) is a sectional view taken along the line AA showing a state in which the reinforcing cylindrical body and the bottom installation cylindrical body are integrated, and (b) is a partially broken sectional view thereof.

Next, embodiments of the reinforcing structure for a cylindrical body for installation on the underwater bottom according to the present invention will be described based on the embodiments shown in FIGS. 1 to 4. In the figure, reference numeral 1 indicates the underwater ground 1, and reference numeral 2 indicates the water surface.

This embodiment will be described using a monopile foundation of an offshore wind power generation facility 4 as an example of the cylindrical body 3 for installation on the bottom of the water.

As shown in FIG. 1, the offshore wind power generation facility 4 includes a cylindrical body 3 for underwater installation (monopile type foundation) that is erected in the underwater ground 1 while penetrating into the underwater ground 1, and a tube for underwater installation. It is equipped with a hollow tower-type tower main body part 5 supported by a shaped body 3, and a wind turbine equipment (nacelle/rotor) 6 supported at the upper end of the tower main body part 5. Together with part 5, it forms a tower shape.

The cylindrical body 3 for installation on the bottom of the water is made of a steel pipe or the like, and is formed into a cylindrical shape with open upper and lower ends. In addition, the aspect of the cylindrical body 3 for underwater bottom installation is not limited to a cylindrical shape, and may be, for example, a rectangular tube shape or the like.

As shown in FIGS. 1 and 2, this cylindrical body 3 for installation on the underwater bottom is struck with its lower side penetrating into the underwater ground 1 to a predetermined depth and its upper side protruding from the underwater ground 1 by a predetermined height. It is set up.

The cylindrical body 3 for installation on the underwater bottom also includes a reinforcing cylindrical body 7 disposed outside the cylindrical body 3 for installation on the underwater bottom, and is reinforced to withstand bending moments and shearing forces generated during earthquakes. ing.

The reinforcing cylindrical body 7 includes an inner tube 8 disposed along the outer periphery of the cylindrical body 3 for installation on the bottom, an outer tube 9 disposed outside the inner tube 8, and an inner tube 8 and an outer tube 9. It is equipped with an upper lid 11 that closes the upper surface of the compartment 10 formed between the compartments 10 and 11, and drains the water in the compartment 10 and reduces the pressure inside the compartment 10, thereby causing water to flow into the water bottom ground 1 due to its own weight and suction load. It is meant to be penetrated.

The length of the reinforcing cylindrical body 7 is determined by analyzing the bending moment and shear force acting on the entire offshore wind power generation equipment 4 or the cylindrical body 3 for installation on the bottom using a structural analysis model, etc., and the analysis results (Fig. 4 Set the penetration length according to the range exceeding the predetermined bending moment and shear force from (see ), and set the penetration length by adding a margin that takes into account the height of the part protruding from the water bottom, etc.

The penetration length of the reinforcing cylindrical body 7 is not limited to the case where it is set based on the analysis results for the target offshore wind power generation equipment, but it is set based on the results of analysis for the target offshore wind power generation equipment, and it is also set for other offshore wind power generation equipment with a similar structural style. It may be set based on the results of past analyzes or the results of measuring the bending moment and shear force acting on the entire offshore wind power generation facility 4 or the cylindrical body 3 for installation on the bottom.

Moreover, this reinforcing cylindrical body 7 is provided with mortar in the gap between the inner surface of the inner tube 8, that is, the surface facing the outer peripheral surface of the cylindrical body 3 for installation on the bottom of the water, and the outer peripheral surface of the cylindrical body 3 for installation on the bottom of the water. It may be filled with a filler 12 such as the like, and integrated with the cylindrical body 3 for installation on the bottom of the water.

This reinforcing cylindrical body 7 is composed of a plurality of divided cylindrical bodies 13, 13 (in this embodiment, a pair) divided in the longitudinal section, and both divided cylindrical bodies 13, 13 are connected to the bottom installation cylindrical body 3. By assembling them from the outside and joining them together, they form a cylindrical shape with a double-pipe structure.

As shown in FIG. 3, each of the divided cylindrical bodies 13, 13 includes an inner tube plate 8a made of a steel plate having a semicircular cross section, and a cross section facing the inner tube plate 8a at a distance from the inner tube plate 8a on the outside in the radial direction. an outer tube plate 9a made of a semicircular steel plate; a fan-shaped upper cover plate 11a that closes the upper surface of the compartment 10 formed between the inner tube plate 8a and the outer tube plate 9a; It includes end plates 14, 14 that close the opening between the circumferential edge of the inner tube plate 8a and the circumferential edge of the outer tube plate 9a, and includes the inner tube plate 8a, the outer tube plate 9a, and the upper cover plate. 11a and both end plates 14, 14, a compartment 10 whose lower surface is open is formed.

By joining these two divided cylindrical bodies 13, 13, the cylindrical inner pipe 8 is formed by the two inner pipe plates 8a, 8a, which are joined to each other, and the cylindrical outer pipe is formed by the two outer pipe plates 9a, 9a. An annular plate-shaped upper lid 11 of the tube 9 is formed by the upper lid plates 11a, 11a.

Each of the divided cylindrical bodies 13, 13 is provided with a plurality of thin plate-shaped reinforcing ribs 15, 15... at intervals in the circumferential direction, and both horizontal edges of the reinforcing ribs 15, 15... It is fixed to opposing surfaces of the tube plate 8a and the outer tube plate 9a by welding or the like, and the inner tube 8 and outer tube 9 are connected via reinforcing ribs 15, 15, . . . and are structurally reinforced.

Each of the reinforcing ribs 15, 15... has a plurality of insertion holes 15a, 15a... that pass through the plate thickness direction at intervals in the longitudinal direction, and the compartments 10 are separated by the reinforcing ribs 15, 15... The insides are interconnected.

Further, a drain pipe 19 is installed so as to pass through the upper cover plates 11a, 11a and communicate with the compartments 10, 10, . . . .

Further, both side edges of each divided cylindrical body 13, 13 are provided with flanges 16, 16 which are continuously formed integrally with the end plates 14, 14, and both the divided cylindrical bodies 13, 13 are assembled to each other. By overlapping the flanges 16, 16 on both side edges with each other and fastening the overlapping flanges 16, 16 with bolts, both the divided cylindrical bodies 13, 13 are joined, and the reinforcing cylindrical body 7 is formed. ing. Incidentally, the reference numerals in the figure indicate bolt insertion holes 16a, 16a, . . . , through which fastening bolts pass, and the reference numeral 16b indicates a fastening bolt.

Further, in the reinforcing cylindrical body 7, an annular rigidity change suppressing member 17 is fixed to the upper lid 11, and the rigidity changes rapidly due to the difference in outer diameter between the bottom installation cylindrical body 3 and the reinforcing cylindrical body 7. It is designed to suppress change.

The rigidity change suppressing member 17 is formed of a steel material or the like into a cylindrical shape with a smaller cross-sectional area than the upper lid 11 or thinner than the reinforcing cylindrical body 7, and is configured to grip the cylindrical body 3 for installation on the bottom of the water. It has become.

Note that the rigidity change suppressing member 17 may be constituted by a plurality of divided rigidity change suppressing members 17a, 17a (a pair in this embodiment) divided along the longitudinal section.

Further, after the reinforcing cylindrical body 7 penetrates into the water bottom 1, a scouring prevention member 18 made of crushed stone or the like is provided on the upper outer periphery of the reinforcing cylindrical body 7 located on the water bottom surface. The surroundings of the body 7 may be prevented from being scoured by tidal currents or the like.

Next, a method for reinforcing the cylindrical body 3 for installation on the underwater bottom according to the present invention will be explained based on FIGS. 5 to 10. Note that the same components as those in the above-described embodiment are given the same reference numerals, and the description thereof will be omitted.

First, the cylindrical body 3 for underwater installation and the offshore wind power generation facility 4 are constructed based on existing construction methods.

Specifically, although not particularly shown, first, a cylindrical body 3 for installation on the bottom, such as a monopile, manufactured in an onshore factory or production yard is transferred to a base port, and at the base port, an elevating work boat (hereinafter referred to as Load onto the SEP ship using the crane of the SEP ship.

Next, the SEP ship loaded with the cylindrical body 3 for underwater installation is transported by sea to the installation area, and then the legs of the SEP ship are lowered and landed on the bottom in the installation area, and the SEP ship body supported by the legs is lifted out of the water. The main body of the SEP ship will be raised to a stable state against waves, etc.

Next, using the crane of the SEP ship, the cylindrical body 3 for underwater installation loaded on the SEP ship is lifted up and erected, and in this state, it is lowered to the underwater ground 1 and placed on the bottom.

Then, the head of the cylindrical body that has landed on the bottom of the water 1 is driven in with a hammer or the like, and the cylindrical body is installed by penetrating into the bottom of the water 1.

When the casting of the cylindrical body 3 for installation on the water bottom is completed, the tower main body 5 with the wind turbine equipment (nacelle/rotor) 6 fixed to the upper end is transferred to the construction water area, and the wind turbine equipment (nacelle/rotor) is attached to the upper end. The tower main body 5 to which 6 is fixed is lifted up by a crane boat or the like, and the lower end of the tower main body 5 is connected to the cylindrical body 3 for installation on the bottom of the water, thereby constructing the offshore wind power generation facility 4.

Note that the object to be reinforced is not limited to the newly installed equipment described above, but may also be the existing offshore wind power generation equipment 4 or the like. Further, the reinforcing cylindrical body 7 may be installed after the bottom installation cylindrical body 3 is cast on the water bottom.

Next, the bending moment and shear force acting on the entire constructed offshore wind power generation facility 4 are analyzed using a structural analysis model, and based on the analysis results obtained for each depth (see the figure), reinforcement The penetration length of the cylindrical body 7 is set, and the length of the reinforcing cylindrical body 7 is determined based on it.

Once the length of the reinforcing cylindrical body 7 is determined, the divided cylindrical bodies 13, 13 that make up the reinforcing cylindrical body 7 are manufactured in a production yard on land, etc., and transported to the construction area, and the reinforcing cylindrical body Install 7.

Incidentally, a scour prevention member 18 may be attached to the upper outer periphery of the divided cylindrical bodies 13, 13 constituting the reinforcing cylindrical body 7.

To install the reinforcing cylindrical body 7, as shown in FIGS. 5 and 6, each divided cylindrical body 13, 13 is lifted from the outside of the cylindrical body 3 for installation on the bottom with a crane or the like (not shown). are placed close to each other with their inner circumferential sides facing each other, and either temporarily suspended above the water bottom ground 1 or temporarily placed on the water bottom ground 1 and sandwiching the water bottom installation tubular body 3 between the two divided cylindrical bodies 13,13. are combined with each other, and the flanges 16, 16 on both side edges are overlapped.

Next, the overlapping flanges 16, 16 are fastened with bolts, the two divided cylindrical bodies 13, 13 are joined, and the reinforcing cylindrical body 7 is assembled along the outer periphery of the cylindrical body 3 for underwater installation. The lower end of the reinforcing cylindrical body 7 is brought to the bottom of the water bottom 1 while adjusting its position. Incidentally, each time the two divided cylindrical bodies 13, 13 are bolted together while temporarily suspended above the water bottom ground 1, they may be sequentially lowered toward the water bottom ground 1.

When the reinforcing cylindrical body 7 reaches the bottom, its lower end penetrates into the water bottom ground 1 to some extent due to its own weight, and the bottom opening of the reinforcing cylindrical body is closed by the water bottom ground 1.

Next, as shown in FIG. 7, the water in the compartment 10 is drained through one or more drain pipes 19 that are installed in advance so as to penetrate the upper lid 11 and communicate with the interior of the compartment 10. Note that the reference numeral 20 in the figure is a drainage pump.

The material of the drain pipe 19 is not particularly limited, and may be made of steel or resin such as polyethylene, as long as it has the strength to withstand water pressure.

At that time, the inside of the compartment 10 is divided into a plurality of parts by reinforcing ribs 15, 15..., but the reinforcing ribs 15, 15... are provided with insertion holes 15a, 15a..., so that the insides communicate with each other. Therefore, the water in the compartment 10 can be appropriately discharged.

When the water in the compartment 10 is discharged and the pressure in the compartment 10 is reduced, as shown in FIG. penetrates into the underwater ground 1.

At that time, a plurality of water pressure gauges are installed at intervals in the circumferential direction on the upper surface of the upper lid 11 of the reinforcing cylindrical body 7, and the reinforcing cylindrical body is It is desirable to check the angle of inclination when the drain pipe 7 penetrates into the underwater ground 1, and adjust the amount of water discharged by the plurality of drain pipes 19 and the on/off state of the drainage pump 20 based on the result.

Note that the means for measuring the inclination angle at the time of penetration of the reinforcing cylindrical body 7 is not limited to the above-mentioned water pressure gauge, and for example, an inclinometer or the like may be used.

Then, as shown in FIG. 9, once the reinforcing cylindrical body 7 has penetrated into the underwater ground 1 to a predetermined depth, the drain pipe 19 is removed and the penetration work is completed.

At this time, since the scour prevention member 18 is attached to the upper outer periphery of the reinforcing cylindrical body 7, the installation of the scour prevention member 18 is completed at the same time as the penetration work of the reinforcing cylindrical body 7 is completed.

When the penetration of the reinforcing cylindrical body 7 is completed, dirt remains between the inner pipe 8 of the reinforcing cylindrical body 7 and the outer periphery of the underwater bottom installation cylindrical body 3. A water jet is injected between the inner pipe 8 of the reinforcing cylindrical body 7 and the cylindrical body 3 for installation on the bottom, and the remaining earth and sand are removed to form a gap, as shown in FIG. A filling material 12 such as mortar is filled in the gap to integrate the underwater bottom installation cylindrical body 3 and the reinforcing cylindrical body 7.

Finally, as shown in FIG. 2, if necessary, a cylindrical shape having a smaller cross-sectional area than the upper cover 11 or thinner than the reinforcing cylindrical body 7 is provided on the upper part of the reinforcing cylindrical body 7 to change the rigidity. The suppressing member 17 is attached, and if necessary, a filler material 12 such as mortar is filled between the rigidity change suppressing member 17 and the outer periphery of the cylindrical body 3 for installation on the bottom of the water, and the reinforcing work is completed.

In the method for reinforcing the cylindrical body 3 for installation on the underwater bottom configured as described above, the reinforcing cylindrical body 7 is installed outside the cylindrical body 3 for installation on the underwater bottom, so that a large bending moment and shearing force act on the cylindrical body 7. The cross-sectional area of the part can be increased, and high resistance to bending moment and shear force can be obtained.

Therefore, safety can be ensured without increasing the outer diameter or wall thickness of the cylindrical body 3 for installation on the underwater bottom, so when installing a new cylindrical body 3 for installation on the underwater bottom, it is possible to use a large-sized crane with a large lifting capacity. The crane of the procured SEP ship can handle the lifting with its lifting capacity without separately arranging a hoist ship, which reduces construction costs and allows the work to be carried out more efficiently.

In this method of reinforcing the cylindrical body 3 for installation on the water bottom, the reinforcing cylindrical body 7 can be reliably penetrated by suction load without relying on driving with a hammer or the like. It can also be used to reinforce the installation tubular body 3.

In addition, although the above-mentioned Example demonstrated the monopile foundation of the offshore wind power generation facility 4 as an example, this invention can also be applied to the steel pipe pile etc. which support the pile support structure, such as a pier.

Furthermore, in the above embodiment, the reinforcing cylindrical body 7 is constructed by two divided cylindrical bodies 13, 13, but it may be constructed by a divided cylindrical body divided into three or more parts. Alternatively, the reinforcing cylindrical body 7 may be integrally formed without using the divided cylindrical body.

Furthermore, water jets may be installed in the reinforcing cylindrical body 7 at the lower ends of the inner tube 8 and the outer tube 9 in order to eliminate obstacles in the underwater ground 1 during penetration.

Further, an ejector may be attached as a pressure reducing device to the drain port of the drain pump 20 for draining water in the compartment 10. By attaching an ejector, it is possible to drive negative pressure by discharging water with a jet stream.

1 Underwater ground 2 Water surface 3 Cylindrical body for underwater installation 4 Offshore wind power generation equipment 5 Tower main body 6 Wind turbine equipment 7 Reinforcing cylindrical body 8 Inner pipe 9 Outer pipe 10 Compartment 11 Upper cover 12 Filler 13 Divided cylindrical body 14 End plate 15 Reinforcing rib 16 Flange 17 Rigidity change suppressing member 18 Scour prevention member 19 Drain pipe 20 Drain pump

Claims (12)

A reinforcing structure for a cylindrical body for underwater installation, which is erected in the underwater ground in a state where it penetrates into the underwater ground,
comprising a reinforcing cylindrical body disposed outside the cylindrical body for installation on the underwater bottom;
The reinforcing cylindrical body includes an inner tube disposed along the outer periphery of the cylindrical body for underwater installation, an outer tube disposed outside the inner tube, and a space between the inner tube and the outer tube. and an upper lid that closes the upper surface of the compartment formed in the
A reinforcing structure for a cylindrical body for installation on the underwater bottom, characterized in that the structure penetrates into the underwater ground by reducing the pressure inside the compartment. The reinforcement structure for a cylindrical body for underwater bottom installation according to claim 1, wherein the reinforcing cylindrical body includes a plurality of reinforcing ribs connecting the inner tube and the outer tube at intervals in the circumferential direction. . The reinforcing structure for a cylindrical body for underwater bottom installation according to claim 2, wherein the reinforcing rib is formed in a plate shape that circumferentially separates the compartment, and has an insertion hole penetrating in the thickness direction. Reinforcement of a cylindrical body for underwater bottom installation according to any one of claims 1 to 3, wherein the reinforcing cylindrical body is provided with a rigidity change suppressing member having lower bending rigidity than the reinforcing cylindrical body at the upper part. structure. The reinforcing structure for a cylindrical body for underwater bottom installation according to any one of claims 1 to 4, wherein the reinforcing cylindrical body is constituted by a plurality of divided cylindrical bodies divided in a longitudinal section. 6. The reinforcing structure for a cylindrical body for underwater bottom installation according to any one of claims 1 to 5, wherein the reinforcing cylindrical body is attached with a drain pipe that penetrates the upper lid and communicates with the compartment. The reinforcing structure for a cylindrical body for underwater bottom installation according to any one of claims 1 to 6, wherein a filler is filled in a gap between the inner tube and the outer peripheral surface of the cylindrical body for underwater bottom installation. A method for reinforcing a cylindrical body for underwater installation, which is erected in the underwater ground in a state where it penetrates into the underwater ground,
an inner pipe arranged along the outer periphery of the cylindrical body for installation on the underwater bottom, an outer pipe arranged outside the inner pipe, and an upper surface of a compartment formed between the inner pipe and the outer pipe. Using a reinforcing cylindrical body comprising an upper lid that closes the
After the lower end of the reinforcing cylindrical body is placed on the outside of the cylindrical body for installation on the water bottom, and the lower end thereof is placed on the bottom of the water,
A method for reinforcing a cylindrical body for installation on the underwater bottom, characterized in that the pressure inside the compartment is reduced and the reinforcing cylindrical body penetrates into the underwater ground. The reinforcing cylindrical body is divided into a plurality of divided cylindrical bodies divided in longitudinal section, and each divided cylindrical body is joined on the underwater bed ground along the outer peripheral surface of the cylindrical body for underwater installation. Item 8. The method for reinforcing a cylindrical body for installation on the bottom of water. After the reinforcing cylindrical body penetrates into the underwater ground, earth and sand between the inner pipe and the underwater bottom installation cylindrical body is removed to form a gap, and the gap is filled with a filler material. The method for reinforcing a cylindrical body for underwater bottom installation according to item 8 or 9. Any one of claims 8 to 10, wherein the shear force and bending moment acting on the cylindrical body for installation on the underwater bottom are analyzed, and the penetration length of the reinforcing cylindrical body is set based on the analysis results obtained for each depth. 1. The method for reinforcing a cylindrical body for installation on the bottom of water. The water bottom installation according to any one of claims 8 to 11, wherein a scouring prevention member is attached to the upper outer periphery of the reinforcing cylindrical body before the reinforcing cylindrical body penetrates into the underwater bed ground. How to reinforce a cylindrical body.

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