JPS61172911A - Method of manufacturing and installing specific gravity type off-shore structure - Google Patents

Abstract

PURPOSE:To facilitate manufacture and installation of a structure, by a method wherein legs are erected upright through ballast control of the legs rotatably coupled to an upper structure, and after the lower end parts of the legs are rotatably coupled to a foundation structure, the foundation structure is secured to a sea bottom. CONSTITUTION:A foundation structure 11, a super-structure 12, and legs 13 are manufactured in a dock, and the legs 13 are rotatably coupled to buyoancy tanks 19 of the upper structure 12 to tug them to an installation sea area. After sea water ballast W is poured in the foundation structure 11 and is sunk down to a position in the vicinity of a sea bottom B, the ballast water W is poured in the spherical parts 26 side of the legs 13 to bring the legs 13 into a standing-upright state, and the legs are moved to a position right above the foundation structure 11. The foundation structure 11 is caused to slightly float, and the lower end parts of the legs 13 are coupled to their respective coupling parts 16 of the foundation structure 11. Further, the assembly is tugged to an installation position, and the ballast water W is further poured in the foundation structure 11 and the legs 13 to seat the foundation structure onto the sea bottom B for securing.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention relates to a gravity-type substructure that is placed on the seabed;
The present invention relates to a method for manufacturing and installing a gravity-type marine structure consisting of a superstructure located above the sea surface and a plurality of legs connecting these.

Conventional technology and its problems Conventionally, gravity offshore structures such as those described above are assembled on land, transported by a launching barge to the installation area, and then lowered from the launching barge into the sea and installed on the seabed. It was getting worse.

However, when the water depth of the installation sea area is deep, the offshore structure becomes larger, which poses a problem in that assembly work on land and loading work onto a launching barge become troublesome. Moreover, there was also the problem that work at heights was required, which was dangerous.

Additionally, due to limitations in the scale of the factory, the capacity of cranes for loading onto the launching barges, and the loading capacity of the launching barges, it is not possible to install large offshore structures for use in deep waters using conventional methods. There wasn't. Furthermore, conventional gravity offshore structures cannot be moved or relocated after installation.

An object of the present invention is to provide a rational method for manufacturing and installing a gravity-type marine structure that solves the above problems.

Means for Solving the Problems The method according to the present invention provides a gravity-type offshore structure consisting of a gravity-type foundation structure that is placed on the seabed, a superstructure that is located above the sea surface, and a plurality of legs that connect these. A method of manufacturing and installing a buoyancy tank, which includes a foundation structure equipped with a buoyancy tank capable of injecting and discharging seawater ballast, a superstructure equipped with a buoyancy tank, and a buoyancy tank capable of discharging seawater ballast. The legs are made separately, and one end of the legs is rotatably connected to the superstructure, and the basic structure is floated on the sea surface, and the legs and superstructure are floated on the sea surface so that the legs lie on their sides. , transport these by sea to the installation sea area, adjust the ballast of the foundation structure to sink it to a predetermined depth, adjust the ballast of the legs to make it upright, adjust the ballast of the foundation structure to lower the lower end of the legs. This includes rotatably connecting the substructure to the substructure, and adjusting the ballast of the substructure and the legs to anchor the substructure to the bottom of the seabed at the installation location.

Note that the upper structure may be of any type as long as at least a portion thereof is located above the sea level.

Embodiment FIG. 1 shows a gravity type marine structure (10) installed on the seabed (B). This marine structure (10) is located on the seabed (B
) and the gravity-type foundation structure (11) that was placed on the bottom of the ocean (
L) Consists of an upper structure (12) located above and four m (13) connecting these.

The foundation structure (11) is made of concrete, for example, and has a box-like shape, and inside thereof, a plurality of buoyancy tanks (14) capable of pouring and discharging seawater ballast (W>) are provided.The upper surface of the foundation structure (11) has four leg coupling devices (16
) are provided symmetrically.

A box-shaped buoyancy tank (19) made of steel and also serving as a storage tank is provided at the bottom of the upper structure (12).

The legs (13) are made of steel pipes, for example, and there are a plurality of buoyancy tanks (2
4) is provided. A small diameter part (25) is formed at both ends of the tapered leg (13) to extend the small diameter part (25), and a connecting spherical part (26) is further formed at the tip of the lower small diameter part (25). is formed, and the tip of the upper small diameter portion (25) is rotatably connected to both sides of the buoyancy tank (19) of the upper structure (12) by a bottle (22).

Details of the coupling device (16) of the basic structure (11) are shown in Figures 5 and 6, and the lower end of the leg (13) can be pivoted into this coupling device (1G) as follows. connected. There are four grooves (27) on the top of the basic structure (11).
They are arranged in a cross shape so as to meet at points, and a hemispherical recess (28) into which the lower half of the spherical part (26) of the leg (13) fits is formed in the bottom wall of the point where these join. Each groove (
27), a leg holding block (29) is fitted so as to be slidable in the radial direction. The inner ends of the blocks (29) are formed into a 90° chevron shape when viewed from the plane so that they come into close contact with each other when they move inward, and the tips thereof are
When viewed from a plane, the quarters are formed so that when the blocks (29) are brought into close contact, a hole is formed whose inner diameter is smaller than the diameter of the spherical part (26) of the leg (13) and slightly larger than the diameter of the small diameter part (25). It is cut out in a circular shape. Also, block (29
) is cut out in a spherical shape so that it comes into contact with the upper half of the spherical part (26) of the leg (13) when they are in close contact with each other. Furthermore, the inner end-upper part of the plot (29) is rounded. The movable rods (30) are arranged in parallel directly below each groove (27), and each movable rod (30)
Both the inner and outer ends of 0) are connected to jacks (31) and (32) fixed within the foundation structure (11). The outer part of the block (29) and the moving rod (30) directly below it
Both ends of a lever (33) are rotatably connected to the intermediate portion of the lever (33), and the intermediate portion of the lever (33) is rotatably attached to the base structure (11) by a pin (34). By pressurizing the inner jack (31), the moving rod (30)
move outward, and the blocks (29) move inward and come into close contact with each other, as shown in FIGS. 5 and 6. vice versa,
By pressurizing the outer jack (32), the moving rod (30) moves inward, and the block (29) moves outward until it reaches the outer end of the groove (27), as shown by the chain line in the figure. . At this time, a gap is created between the tip ends of the blocks (29) through which the spherical portions (26) of the legs (13) can pass. By releasing all the jacks (31) and (32) and pressing the bulbous part (26) of the leg (13) from above against the rounded part at the top of the inner end of the block (29), the block (29) are pushed outward and the bulbous portion (26) passes between the inner ends of the block (29) and fits into the recess (28). In this state, the inner jack (31) is pressurized and the block (29) is moved inward and brought into close contact, so that the lower inner end of the block (29) comes into contact with the upper half of the spherical part (26). hold this.

As a result, the legs (13) are connected to the coupling device (16) and cannot move up and down, but there is a slight gap between the small diameter part (25) and the inner end of the block (29), and the block ( 29) is rounded at the top of the inner end, so
The legs (13) can rotate by a certain angle in all directions. Also,
From this state, the inner jack (31) is released and the outer jack (32) is pressurized to move the block (29) to the outer end, thereby removing the spherical part (2).
6) can be pulled upwardly from between the inner ends of the block (29) to separate the leg (13) from the coupling device (16). Note that the jacks (31) and (32) are remotely controlled from the sea.

At the center of the base structure (11) and superstructure (12),
Although not shown in the drawings, holes for various types of piping are provided that pass through these up and down. Furthermore, the buoyancy tank (19) of the superstructure (12) is submerged below the sea surface (L) to reduce wave force resistance on the sea surface.

Next, with reference to FIGS. 1 to 4, a method for manufacturing and installing the above-mentioned gravity-type marine structure (10), that is, one example of the method of the present invention will be described.

First, the foundation structure (11), superstructure (12) and legs (13) are manufactured separately in the dock (35) (see Figure 2).The superstructure (12) and legs (13)
During or after the construction of the buoyancy tank (19) of the superstructure (12), one end of the leg (13) lies on its side.
Connect it so that it can rotate.

Next, water is poured into the dock (35) to float the substructure (11) on the sea surface (L), and the superstructure (12) and legs (13) are placed on the sea surface (L) so that the legs (13) lie on their sides. ) and transported by sea by towing to the installation area.

Next, in the installation sea area, an appropriate amount of seawater ballast (W) is injected into the foundation structure (11), and the ballast is allowed to settle close to the seabed (B).

Next, an appropriate amount of seawater ballast (W>) is poured into the spherical part (26) side of the leg (13), the leg (13) is made to stand upright, and it is moved directly above the foundation structure (11) ( (See Figure 3).

Next, some of the seawater ballast (W>) of the foundation structure (11) is drained, and it is floated a little, so that the lower end of the leg (13) can be rotated to the connection device (16) of the foundation structure (11). Connect to.

Next, this is towed to the installation position, further seawater ballast (W) is poured into the foundation structure (11) and legs (13), and it is fixed on the seabed (B) (Fig. 1). reference). This completes the installation of the marine structure (10).

In the case of this marine structure (10), both ends of the legs (13) are rotatably connected to the foundation structure (11) and the superstructure (12), allowing the legs (13) to swing; The superstructure (12) can always be held horizontally.

When the intended purpose of operation of the offshore structure (10), such as oil drilling, has been completed, seawater ballast (
W) is partially drained and the entire marine structure (10) is moved to the seabed (B).
) and can be towed and relocated to another location. If the distance to be moved is long or for other reasons, the foundation structure (11) may be attached to the legs (
It is also possible to separate them from 13) and float them to the sea surface (L), and tow them separately.

In the above embodiment, the legs (13) are erected at a slightly deeper water depth than the installation position and connected to the foundation structure (11); It is also possible to connect this to the bottom and let it land on the bottom as it is.

In the above embodiment, since the leg connecting device (16) as shown in FIGS. 5 and 6 is used, the work of connecting the legs (13) during installation is extremely simple. However, the leg connecting means is not limited to that of the above embodiment. Further, the configuration of each part of the marine structure is not limited to that of the above embodiment, and can be modified as appropriate. For example, if the weather and sea conditions in the installation area are severe and the gravity of the foundation structure alone is not sufficient to provide stability, short piles can be installed on the bottom of the foundation structure to increase stability.

Effects of the Invention Since the method according to the present invention is configured as described above, it becomes possible to easily manufacture and install large marine structures for use in deep sea areas. That is, since the foundation structure, superstructure, and legs are manufactured separately, the scale constraints of the factory are relaxed, and it becomes possible to manufacture a single large-scale offshore structure. Furthermore, since the foundation structure, superstructure, and legs are equipped with buoyancy tanks, there is no need to use carriers or cranes for transporting, unloading, or installing them, which alleviates the constraints imposed by the capacity of carriers and cranes, and allows for large-scale marine applications. It becomes possible to manufacture and install structures.

Furthermore, since the basic structure and legs are equipped with buoyancy tanks, it is possible and easy to move or relocate the system after installation.

Further, since the legs are rotatably connected to the foundation structure and the superstructure, the legs can be moved by 1 degree, and the superstructure can always be held horizontally. Furthermore, the resistance in the underwater part is also reduced.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway side view of a gravity type offshore structure manufactured and installed by the method of the present invention, and Figs. 5 is a partially cutaway side view, FIG. 5 is an enlarged plan view showing a portion of the leg connecting device of the basic structure, and FIG. 6 is a sectional view taken along line A--FIG. 5. (10)...Gravity offshore structure, (11)...Foundation structure, (12)...Superstructure, (13)...Legs, (
14) (19) (24)...buoyancy tank, (16
)...Leg connection device. that's all

Claims (1)

[Claims] A method for manufacturing and installing a gravity-type marine structure consisting of a gravity-type foundation structure that is placed on the seabed, a superstructure located above the sea surface, and a plurality of legs that connect these structures. Therefore, a foundation structure equipped with a buoyancy tank capable of injecting and discharging seawater ballast, a superstructure equipped with a buoyancy tank, and legs equipped with a buoyancy tank capable of discharging seawater ballast were made separately. One end of the leg should be rotatably connected to the superstructure, and the foundation structure should be floated on the sea surface, and the legs and superstructure should be floated on the sea surface with the legs lying on their sides, and then transported by sea to the installation area. Adjusting the ballast of the foundation structure allows it to sink to a predetermined depth; Adjusting the ballast of the legs allows it to stand upright; Adjusting the ballast of the foundation structure allows the lower end of the leg to rotate around the foundation structure. A method for manufacturing and installing a gravity-type offshore structure, comprising: connecting the structure to the base structure; and adjusting the ballast of the base structure and legs to bring the base structure to the bottom of the seabed at the installation location and fixing the base structure.