JPH0794234B2 - Offshore platform fixed structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mooring system for an offshore platform used as a quay at a maritime airport, a marine distribution center, or the like.

[Conventional technology]

Recently, due to skyrocketing land prices and restrictions on installation locations,
Heliports and distribution centers are set to be established on the sea. As such a sea base, a landfill type and a floating type are known, but the former has a limited installation sea area and causes environmental damage. Therefore, the floating type base is preferable.

This floating offshore base supports superstructures with smooth top surfaces by buoyancy structures, which are made of steel or prestressed concrete (PC). Then, such a structure is fixed by mooring on the sea. As a mooring method for this structure, for example, a tension leg method, a catenary method, a dolphin method, a ballast fixing method, etc. have been proposed.

By the way, if the floating sea base is used as a business space where humans live, for example, or if it is used as a railway, it is necessary to suppress its sway, so that it is not affected by wind power, waves, tide changes, etc. Must be moored.

The tension leg system is used as the motion suppression mooring system.
The ballast setting method is selected.

[Problems to be Solved by the Invention]

By the way, in the above-mentioned inner tension leg system of the motion suppression type mooring system, not only there is a technical problem in obtaining a large space, but also the maintenance becomes difficult.

In addition, in the ballast settling method, the buoyancy of the structure changes as the tide changes and the water changes due to waves. Therefore, there is a problem in that a ballast that withstands the maximum buoyancy predicted in advance must be used, and therefore the foundation to be fixed must be solid.

[Means for Solving the Problems]

The present invention has been made to solve the above-mentioned problems of the prior art, and has the following two structures.

1) A wave control structure 5 in which an offshore platform 1 in which a lower hull 2 having a buoyancy adjusting device and an upper hull 3 having a flat upper surface are connected by a column 4 is laid on the wave input side.
And a device for holding at a predetermined position by a foundation structure 8 provided behind the wave control structure 5 at a prescribed interval, the foundation structure 8 side being above the wave control structure 5. The locking parts 7 projecting to the sea, and the locking parts 9 projecting to the wave control structure 5 side are provided on the upper part of the substructure 8, respectively, and the offshore platform 1 is provided between the wave control structure 5 and the substructure 8. This is a mechanism for fixing an offshore platform in which the upper hull 3 of the lower platform 2 is engaged with each other and the upper hull 3 of the lower platform 2 is adjusted by the engaging portions 7 and 9 by adjusting the buoyancy of the lower hull 2.

2. A wave control structure 5 in which an offshore platform 1 in which a lower hull 2 having a buoyancy adjusting device and an upper hull 3 having a flat upper surface are connected by a column 4 is laid on the wave input side,
This is a device for holding at a predetermined position by a foundation structure 8 provided behind the wave control structure 5 at a prescribed interval, and heading toward the foundation structure 8 side above the wave control structure 5. The notch 10 is formed, the offshore platform 1 is fitted between the wave control structure 5 and the substructure 8, and the buoyancy of the lower hull 2 is adjusted to adjust the upper hull 3 of the offshore platform 1.
This is a mechanism for fixing an offshore platform in which one lower surface is fitted and supported in the notch portion 10 and the other lower surface is supported on the upper surface of the substructure 8.

[Work]

According to the fixed structure of the offshore platform having the above-described structure, the rolling due to the waves is prevented by the wave control structure 5, and the vertical shaking due to the change in the tide level causes the buoyancy of the offshore platform and the basic structure in the embodiment of FIG. Thing 5
And the sea by the locking force by the locking parts 7 and 9 provided at the upper end of the wave control structure 8 or the supporting force supported on the wave control structure 5 and the foundation structure 8 in the embodiment of FIG. The platform can be fixed in place.

〔Example〕

An embodiment of a structure for fixing an offshore platform according to the present invention will be described below with reference to the drawings.

FIG. 1 is a side view of an offshore platform 1. The offshore platform 1 is configured by connecting a lower hull 2 having a buoyancy adjusting device such as a ballast tank and an upper hull 3 having a smooth upper surface with a plurality of columns 4. Has been done.

2 and 3 are a plan view and an enlarged cross-sectional view of the installation location of the offshore platform 1,
Reference numeral 5 denotes a wave control structure (one support structure) provided on the front surface of the wave input side indicated by an arrow F.
Is made of reinforced concrete or the like so that the lower end projects on the seabed 6 and the upper end projects above the sea surface, and a locking portion 7 is provided on the upper end. On the other hand, 8 is a substructure (the other support structure), and this substructure 8 is arranged behind the wave control structure 5, and a plurality of substructures 8 are provided at a predetermined interval L. This substructure 8 is also arranged so that the lower end is driven into the seabed 6 and the upper end projects above the sea surface, and a locking portion 9 is provided at the upper end.

And the offshore platform 1 built in the factory is towed to the installation site, ballasted and slightly submerged,
As shown by the dotted line in FIG. 2, it is drawn between the wave control structure 5 and the substructure 8, and then the ballast is discharged and levitated. By doing so, the offshore platform 1 levitates as shown in FIG. 4, and the locking portion 7 of the wave control structure 5 is moved.
And the locking portion 9 of the substructure 8 is the offshore platform 1.
The offshore platform 1 can be fixed by abutting the upper surface of the offshore platform 1 by both supporting structures.

Of course, the buoyancy of the offshore platform 1 changes due to the ebb and flow of the tide. Therefore, it is preferable to detect this buoyancy and adjust the ballast so that the buoyancy is always slightly larger than gravity.

FIG. 5 shows another embodiment, in which a notch 10 is formed at the upper end of the wave control structure 5, and both sides of the offshore platform 1 are supported on the notch 10 and the substructure 8. It is like this. In this case, lower hull 2 in advance
The ballast in the interior is discharged to levitate the offshore platform 1, and then the offshore platform 1 is drawn between the substructure 8 and the wave control structure 5. Then, the ballast is stretched and allowed to sink, and the wave control structure 5 and the substructure 8 as described above.
Support at the top of the. At this time, similarly to the above, it is preferable to operate the buoyancy adjusting device so that the gravity is slightly larger than the buoyancy and reduce the gravity load acting on the wave structure 5 and the substructure 8.

〔The invention's effect〕

As is apparent from the above description, the structure for fixing an offshore platform according to the present invention is: 1) The offshore platform 1 in which the lower hull 2 having a buoyancy adjusting device and the upper hull 3 having a flat upper surface are connected by the column 4 on the wave input side. A wave control structure 5 laid on the sea and a foundation structure 8 provided behind the wave control structure 5 at a predetermined distance to hold the wave control structure 5 at a predetermined position. 5, a locking portion 7 protruding toward the substructure 8 side is provided on the upper side of the substructure 5, and a locking portion 9 protruding toward the wave control structure 5 side is provided above the substructure 8, respectively. The offshore platform 1 is fitted between the objects 8, the buoyancy of the lower hull 2 is adjusted, and the upper surface of the upper hull 3 of the offshore platform 1 is locked by the locking portions 7 and 9.

2) Further, a wave control structure 5 in which an offshore platform 1 in which a lower hull 2 having a buoyancy adjusting device and an upper hull 3 having a flat upper surface are connected by a column 4 is laid on the wave input side, and the wave control structure 5 Is a device which is held at a predetermined position by a substructure 8 which is provided at a predetermined distance behind the substructure, and which has a notch 10 formed on the upper part of the wave control structure 5 toward the substructure 8 side. , The offshore platform 1 is fitted between the wave control structure 5 and the substructure 8 and the buoyancy of the lower hull 2 is adjusted to adjust the upper hull 3 of the offshore platform 1.
One of the lower surfaces is fitted and supported by the cutout portion 10, and the other lower surface is supported by the upper surface of the substructure 8.

Therefore, the wave control structure 5 provided on the wave input side suppresses the waves and suppresses the sway of the offshore platform due to the waves.

Further, in the embodiment of FIG. 4, the buoyancy of the offshore platform 1 is made larger than its weight so that the up and down movement due to the ebb and flow of the tide and the wave are held by the locking portions 7 and 9, and the up and down movement is controlled by the wave control structure 5.
It can be suppressed by utilizing the engaging force between the substructure 8 and the offshore platform 1.

Further, in the embodiment of FIG. 5, contrary to the above-mentioned means, the buoyancy of the offshore platform 1 is made smaller than its weight to be supported on the wave control structure 5 and the upper part of the substructure 8 to generate a supporting force, and the wave control is performed. The engagement force fitted between the structure 5 and the substructure 8 can form a stable offshore base while suppressing the vertical sway and the anteroposterior sway due to tides and waves.

Also, since the offshore platform floats by itself, it is towed from the place where it was built to the place where it will be installed, and it is carried in between the wave control structure, which is the supporting structure, and the foundation structure,
Since the support structures can bear a part of the weight of the offshore platform, it is possible to fix the support structures without applying an excessive force. Also, the installation work is simple and can be completed in a short time.

[Brief description of drawings]

FIG. 1 shows an embodiment of a structure for fixing an offshore platform according to the present invention. FIG. 1 is a side view of the offshore platform, FIG. 2 is a plan view of a place where the offshore platform is installed, and FIG. FIG. 4 is a side sectional view of the offshore platform in a fixed state, and FIG. 5 is an enlarged sectional view of essential parts in another embodiment. 1 …… Offshore platform 2 …… Lower hull 3 …… Upper hull 4 …… Column 5 …… Wave control structure 6 …… Sea floor, 7,9 …… Locking part 8 …… Foundation structure, 10 …… Notch

Claims (2)

[Claims] 1. A wave control structure in which an offshore platform (1) in which a lower hull (2) having a buoyancy adjusting device and an upper hull (3) having a flat upper surface are connected by a column (4) is laid on the wave input side. (5) and a device for holding the wave control structure (5) at a predetermined position by a foundation structure (8) provided at a predetermined interval behind the wave control structure (5). ), The locking portion (7) protruding toward the substructure (8) side, and the locking portion (9) protruding toward the wave control structure (5) side above the basic structure (8), respectively. The offshore platform (1) is fitted between the wave control structure (5) and the substructure (8), and the buoyancy of the lower hull (2) is adjusted to adjust the upper hull (3) of the offshore platform (1). The upper surface of the lock is locked by the locks (7) and (9) Upper platform fixing mechanism. 2. A wave control structure in which an offshore platform (1) in which a lower hull (2) having a buoyancy adjusting device and an upper hull (3) having a flat upper surface are connected by a column (4) is laid on the wave input side. (5) and a device for holding the wave control structure (5) at a predetermined position by a foundation structure (8) provided at a predetermined interval behind the wave control structure (5). ), A notch (10) facing the side of the substructure (8) is formed, and the offshore platform (1) is fitted between the wave control structure (5) and the substructure (8), and the lower hull is attached. By adjusting the buoyancy of (2), one lower surface of the upper hull (3) of the offshore platform (1) is fitted and supported in the notch (10), and the other lower surface is supported by the upper surface of the substructure (8). The fixing mechanism for the offshore platform.