JPS61172914A - Method of manufacturing and installing sepcific gravity type off-shore structure - Google Patents

Abstract

PURPOSE:To facilitate manufacture of an off-shore structure at a deep sea area, by a method wherein a foundation structure and legs, which are separately manufactured and marine-transported to a spot having a depth of a long distance, are rotatably inter-coupled and are sunk under a water surface, and the legs are coupled to a super- structure transported to a position right thereablve. CONSTITUTION:A foundation structure 11, an upper structure 12, and legs 13, which are separately manufactured in a dock, are floated on a sea surface L, and are marine- transported to a spot having a depth of a long distance in the vicinity of an installation sea area. The one end parts of the legs 13 are rotatably coupled to a foundation structure 11 through pins 26 as ballast W is controlled, and the foundation structure 11 and the legs 13 are sunk down to a level under a sea surface L. After the upper structure 12 is positioned on the sea surface L above the legs 13 erected upright, the legs 13 are slightly surfaced through discharge of the ballast W to intercouple the super-structure 12 and the legs 13. Thereafter, the assembly is tugged to a given installation position and is seated on a sea bottom, and this completes installation of an off-shore structure.

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 basic structure, superstructure, and legs must be floated on the sea surface and transported by sea to the installation area.
By adjusting the ballast of the foundation structure and legs, one end of the leg can be rotatably connected to the foundation structure, and the foundation structure and the legs can be lowered below sea level, while the legs can be made to stand upright. , by levitating these, rotatably connecting the upper ends of the legs to the superstructure, and further lifting the superstructure above sea level, and adjusting the ballast of the foundation structure and the legs to move the foundation structure to its installation position. This includes landing on the seabed and fixing it.

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 offshore structure (io) is located on the ocean floor (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 legs (13) connecting these.

The foundation structure (11) is, for example, made of concrete and has a box-like shape, and a plurality of buoyancy tanks (14) capable of pouring and discharging seawater ballast (W) are provided inside the foundation structure (11). As shown in FIG. 6, holes (15) for various types of piping are provided in the center of the basic structure (11), passing through it vertically.

Four leg connecting devices (1G), which will be described later, are symmetrically provided on the upper surface of the basic structure (11), and grooves (17) into which half of the legs (13) fit into the outer part of each connecting device (16). is formed.

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 center of this buoyancy tank (19) is also provided with holes (20) for various types of piping that pass through it vertically.

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 tapered leg (13) to extend the small diameter part (25), and a connecting spherical part (26) is further formed at the tip of the small diameter part (25).
is formed.

Details of the connecting device (16) of the basic structure (11) are shown in FIGS. 7 and 8, and the lower end of the leg (13) is connected to this connecting device! (16) is rotatably connected. Four grooves (27) are provided in the upper surface of the foundation structure (11) in a cross shape so that they meet at one place, and the lower half of the spherical part (26) of the leg (13) is placed on the bottom wall of the meeting point. A hemispherical recess (28) into which the parts fit is formed.A leg holding block (29) is fitted into each groove (27) so as to be slidable in the radial direction.The inner end of the block (29) The parts are formed in 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 of the parts have an inner diameter that is similar to that of the leg (13) when the block (29) comes into close contact with each other.
The notch is cut in a quadrant shape when viewed from above, so that a hole is formed which is smaller than the diameter of the spherical part (26) and slightly larger than the diameter of the small diameter part (25). Also, block (2
The lower inner end of 9) will form the leg (13) when they are in close contact.
It is cut out in a spherical shape so as to be in contact with the upper half of the spherical part (26). Furthermore, the upper inner end of the block (29) is rounded. A movable rod (30) is 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 middle part of the lever (33), and the middle part 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. 7 and 8. 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 spherical 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) is released. It is pushed outward and the bulbous part (
26) passes between the inner ends of the block (29) and fits into the recess (28). In this state, pressurize the inner jack (31), move the block (29) inward, and press W! By observing the small diameter part of the block (29)
25) and the inner end of the block (29), and the upper inner end of the block (29) is rounded so that the leg (13) can be rotated by a certain angle in all directions. I can move. In addition, from this state, the inner jacking (3
1) and pressurizes the outer jack (32) to move the block (29) to the outer end, thereby pulling out the spherical part (26) upward from between the inner ends of the block (29). The leg (13) can be separated from the coupling device (1G) by
is operated remotely from the sea.

The same four leg coupling devices (21) are provided upside down on the underside of the buoyancy tank (19) of the superstructure (12), and the upper ends of the legs (13) can rotate on these. is connected to.

Next, with reference to FIGS. 1 to 5, an example of a method for manufacturing and installing the above-mentioned gravity-type marine structure (10), ie, a method of the present invention, will be described.

First, the substructure (11), superstructure (12) and legs (13) are manufactured separately within the dock (35) (see FIG. 2).

Next, pour water into the dock (35) and substructure (11).
, the superstructure (12) and the legs (13) are floated on the sea surface (L) and transported by sea by towing to the installation sea area.

Next, apply an appropriate amount of seawater ballast (W) to the foundation structure (11) at a location slightly deeper than the installation location in the installation sea area.
is poured with water to settle it a little, and one end of the four legs (13) is positioned above the groove (17) of the foundation structure (11). And seawater ballast (W) of the basic structure (11)
Drain a portion of the water to make it float a little, and create four legs (13).
Insert the lower half of one end into the corresponding groove (17) (
(See Figure 3). As a result, the spherical part (26) of the leg (13)
) is located almost directly above the connecting device (1G) of the foundation structure (11).

Next, the foundation structure (11) and the foundation structure (11) of the legs (13).
) side by pouring an appropriate amount of seawater ballast (W>) to settle the foundation structure (11), and at the same time sink the foundation structure (11) side of the leg (13) and make it slanted, and lower the lower end of the leg (13). and the base structure (11) and the legs (13).
Furthermore, seawater ballast (W) is injected into the water, and these are brought to sea level (
L) While sinking downward, use the buoyancy of the upper part of the leg (13) to make the leg (13) stand upright.

Next, move the superstructure (12) directly above the legs (13) (see Figure 4), drain some of the seawater ballast (W) from the foundation structure (12) and legs (13), and remove them a little. The upper end of the leg (13) is connected to the connecting device (12) of the upper structure (12).
21). Then, the seawater ballast (W>) is further drained and the superstructure (12) is brought back to sea level (L).
Lift it upward and tow it to the installation position (see Figure 5).

Finally, in the installation position, the foundation structure (11) and (
Further, seawater ballast (W) is injected into 13), and this is brought to the bottom of the seabed (B) and fixed (see Figure 1). 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 (
Part of W) is removed and the entire marine structure (10) is constructed on the seabed (B).
) and can be towed and relocated to another location.

In the above embodiment, the leg connecting devices (16) (21) as shown in Figs. 7 and 8 are used, so the legs (16) (21) during installation are
13) The connection work 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, the weather in the installation area,
If the sea conditions are severe and the gravity of the foundation structure alone is not sufficient to provide stability, short piles can be installed on the underside 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, making it possible to manufacture large-scale offshore structures. 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.

Furthermore, since the legs are rotatably connected to the base structure and the superstructure, the legs can swing 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. FIG. 6 is a plan view of the basic structure shown in FIG. 2, FIG. 7 is an enlarged plan view of the leg connection device shown in FIG. 6, and FIG. - It is a sectional view of the A line. (10)...Gravity offshore structure, (11)...Foundation structure, (12)...Superstructure, (13)...Legs, (
14) (19) (24)...buoyancy tank, (16
) (21)...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. To separately create a foundation structure equipped with a buoyancy tank capable of pouring seawater ballast, a superstructure equipped with a buoyancy tank, and legs equipped with a buoyancy tank capable of pouring seawater ballast; The foundation structure, superstructure, and legs are floated on the sea surface and transported by sea to the installation area, and one end of the leg is rotatably connected to the foundation structure by adjusting the ballast of the foundation structure and the legs, and the foundation structure and the legs are floated on the sea surface. By lowering the vessel to the bottom, raising the legs upright, and adjusting the ballast of the foundation structure and legs, they can be raised to the surface, and the upper ends of the legs can be rotatably connected to the superstructure, and the superstructure can be held above sea level. A method for fabricating and installing a gravity-type offshore structure, which includes raising the structure, and adjusting the ballast of the foundation structure and legs to bring the foundation structure to the bottom of the seabed at the installation location and fixing it.