JPS6118586A - Construction of ocean structure - Google Patents

Abstract

PURPOSE:To construct a large scale ocean structure efficiently by assembling the base section then floating on the ocean and while rotating through a towboat and the like, assembling the upper structure onto the base section by means of a crane on the land. CONSTITUTION:The base section 1 of an ocean structure is assembled in dock then floated on the ocean 4 and moored to the quay 2. A crane 3 is installed at the quay 2 while extending the boom to the ocean 4. The base section 1 is rotated at the site by means of a towboat 6 on the ocean 4 and a winch 5 on the land. The upper structure is assembled sequentially onto the base section 1 by means of the crane 3 thus to construct a large scale ocean structure. In such a manner, large scale ocean structure can be constructed efficiently without requiring special large scale construction facility.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of constructing a large marine structure.

[Conventional technology]

There are two types of offshore structures: those that are used floating and those that are submerged. All types of structures are constructed where the facilities are as ready as possible and then towed to the site while floating. Alternatively, it is common to transport it on a purge.

A conventional method of constructing such a marine structure will be explained with reference to FIGS. 4 to 11.

Figure 4 shows blocks (α) and (b) constructed using existing dogs, etc., and blocks (a) and (b)'
t This is a construction method that connects them in one piece, but reliable joining technology for the underwater part has not yet been developed, and due to turbulence caused by waves,
Blocks (α) and (b) had the disadvantage of requiring a huge amount of equipment to fix them together.

Figure 5 shows a construction method in which a marine structure (d) is built integrally on a fixed platform (c) on land and launched into the water, but the crane lift is higher and more efficient than when building with a dog. However, depending on the water depth, the underwater fixed platform (g) had to be extended far offshore depending on the water depth, making the work difficult.

Figure 6 shows a method in which a temporary open-pit dog (f) is built on land near the coast in advance, and an offshore structure (d) is built integrally with the structure separated by a partition door (g). If the structure is completed, there will be considerable swamping, so marine structures (d3
In order to float and pull out a temporary dog <fI, it requires a large amount of excavation of the seabed in front, which is uneconomical. Therefore, as shown in Fig. 7, a method is being used in which only the foundation part (h) of the marine structure is constructed in a temporary dog (A), and the upper structure is continued to be constructed while it is floating on the sea. Although this method requires less excavation of the temporary dog (A), it has the disadvantage of being inefficient because the construction of the upper structure is carried out at sea.

Next, regarding the lifting equipment used when constructing offshore structures, when using a gantry crane, the larger the span, the heavier the structure and the less economical the gantry crane becomes. As shown in Figures 8 and 9, when constructing an offshore structure (d) using a dog (), including a temporary dog, a tower crane (j
) to move construction materials, but in this case, in order to move the entire offshore structure (d), at least two tower cranes are required due to the reachable distance of the tower crane (j). (j) is not only required, but if the center of the offshore structure (d) is not reachable or the lifting capacity is insufficient, another base climbing system on the offshore structure may be required. Since equipment such as a crane is required, and the number of material supply routes (k) increases depending on the number of cranes, there is a disadvantage that the labor involved in transporting materials becomes uneconomical.

In addition, as shown in Figures 10 and 11, marine structures (d
) to be constructed on the sea, a 70-ton crane (j) must be used, but the floating crane (1) operates more slowly than a land-based crane, and in order to provide a stable supply of materials, it is difficult to transport the materials. This requires an accompanying barge and transportation purge from land, resulting in inefficient sea transportation.

[Problem that the invention seeks to solve]

The present invention aims to construct offshore structures with high efficiency using the minimum number of land cranes.

[Means for solving problems]

The present invention is a method of constructing an offshore structure in which a foundation is assembled, the foundation is floated and rotated, and an upper structure is assembled on the foundation by a crane on land.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Fig. 1, (1) is the foundation of the marine structure, which is assembled using a dog or the like, floated, pulled out to a quay (2), and moored. There is a crane (3) on the quay (2).
) is installed, and its boom extends toward the sea (4).

Foundation part (1) moored under the boom of crane (3)
rotates while floating, and uses a crane (3) to assemble the upper structure of the offshore structure on the foundation (1). Rotating base part (1), land winch (5)
and several temporary winches are installed on the foundation (1), pulled together by a tugboat (6) on the sea (4), etc.
An anchor may be installed on land or on the ocean floor to pull a wire. The force required to rotate the base part (1) is:
Since the foundation part (1) is floating, it can be considered that its own weight is zero, and the wave-making resistance that occurs due to the rotation is hardly a problem because it is carried out at extremely slow speed for safety reasons, and there is only a slight It is sufficient to have enough force to overcome the kinematic and viscous resistance of the water, and therefore an extremely small force is required, although this varies depending on the contact area with the water in the underwater part of the base portion (1) and the shape.

By rotating the foundation part (1), the crane (3
) remains fixed or travels only a minimum distance, and the upper surface of the foundation (1) is sequentially moved by a crane (3).
Since the material supply route (7) is within the reach of The work can be done without the need for a marine crane. Materials for the upper structure are supplied by the crane (3) from one side, but since the planar area of the foundation part (1) is large, the slope of the foundation part (1) is extremely slight, and 1. It is difficult to assemble the upper structure. It will never occur.

The embodiment shown in FIG. 2 is a case where a pre-assembled foundation part (1) is rotated on the sea (4) at the corner of a quay (2) and two cranes (3) are used.

Figure 3 shows an example of using a construction dog (8) exclusively for offshore structures.After the foundation is assembled with the construction dog (8) drained, water is poured into the construction dog (8). Float the foundation part (1) and use the winch (5) to lift the foundation part (
1), assemble the upper structure using the crane (3).

〔Effect of the invention〕

When constructing offshore structures, the present invention eliminates the need to use inefficient floating cranes, makes it possible to efficiently use only land-based cranes, and improves efficiency by consolidating material supply routes. It is also possible to reduce the amount of excavation for temporary open pit dogs.

[Brief explanation of drawings]

Figures 1 to 3 are plan views showing embodiments of the present invention, Figures 4 to 7 are side views of the conventional construction method,
Figure 8 is a plan view of another conventional method, and Figure 9 is the I of Figure 8.
10 is a plan view of still another conventional method, and FIG. 11 is a sectional view taken along the line XI-XI in FIG. 10. In the figure, (1) shows the foundation, (2) the quay, (3) the crane, and (8) the construction dog.

Claims (1)

[Claims] 1) A method for constructing an offshore structure, which comprises assembling a foundation, floating the foundation in water, rotating it, and assembling an upper structure on top of the foundation using a crane on land.