JPH039251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for constructing concrete offshore structures at sea.

[Conventional technology]

Concrete offshore structures are used for large structures such as offshore airports, offshore petroleum storage bases, and floating breakwaters.

Traditionally, large structures like this were built on land or in a dock, and the nearly completed structure was either hoisted up by a crane and floated out to sea, or launched from a dock and towed to the desired area.

However, in order to float a large structure built on land or in a dock, it is necessary to launch it using a large crane ship, which takes a long time, and there is a problem that it is less economical. It was hot. Additionally, when moving a large concrete structure during the launching process, there were accidents such as cracks appearing in the structure due to poor stress generation conditions.

In order to solve the above-mentioned problems, studies have been carried out to construct these concrete offshore structures at sea, but an efficient construction method in terms of strength and watertightness has not yet been proposed. This is the current situation.

The present invention solves the problems of the conventional concrete marine structure construction method, and includes:
Its purpose is to be easy to construct and launch;
Moreover, it proposes a construction method that can easily construct large structures.

[Means to solve the problem]

The construction method for constructing a concrete marine structure at sea according to the present invention in order to achieve the above object is as follows: (A) a bottom plate, side frames projecting in a U-shape from both sides of the bottom plate, and both ends in the longitudinal direction; of a steel frame consisting of a partition wall provided at a distance between the bottom plate and the side frames, concrete is poured between at least the peripheral surface of the partition wall and the bottom plate and both side frames, and the upper (B) launching the floating body and connecting a plurality of floating bodies at sea to form a lower structure; (C) forming a superstructure on the lower structure; and (D) pouring concrete into the formwork for the lower and upper structures.

[Effect]

On land, a floating body (small block) consisting of a steel frame with a length divided into several parts of the target large concrete offshore structure is constructed, launched, and the steel frames are connected at sea. A large concrete offshore structure can be constructed by forming the lower structure of a marine structure of a predetermined length, forming a formwork for the upper structure on top of the lower structure, and then pouring concrete. can.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings.

(A) First, in the present invention, a concrete offshore structure is constructed at a location where a block-shaped steel frame 1 having a length divided into several parts can be launched, such as a dock or a seawall.

This steel frame 1 is a small block for constructing the lower structure of a concrete offshore structure, and has a U-shaped cross section with side frames 2 standing upright on both sides of a bottom plate 3. Further, partition walls 4 are provided at both ends in the longitudinal direction, and the whole is formed into a box shape.

Anchor members 5a are provided on the inner surfaces of the bottom plate 3 and both side frames 2 to increase adhesion to concrete to be cast. In addition, the partition wall 4
A stud dowel 5 is provided on the flange surface around the flange in the same manner as described above.

Furthermore, a jig 6 is provided between the partition wall 4 and the bottom plate 3.
This bottom plate 3, both side frames 2 and this partition wall 4 are arranged.
The partition wall 4 is supported with an appropriate distance between the flange surface of the partition wall 4 and the flange surface of the partition wall 4. Then, as shown in FIGS. 1 and 2, concrete P is placed so as to close the gap between the partition wall 4 and the steel frame 1 formed on three sides.

The height of this concrete P on the side frame 2 side is L
may be slightly higher than the water intake WL when the formed steel frame 1 is floated on the ocean, in short, the frame 1 is configured to be a box-shaped floating body. It is necessary.

As shown in FIG. 1, the concrete P is placed between the two partition walls 4 and
It is most preferable to cover almost the entire length of the bottom plate 3 excluding both ends (the parts to be welded).
As shown in the figure, it is also possible to perform the treatment locally at least on both side surfaces and the bottom surface of the partition wall 4.

Further, when the concrete P is placed, reinforcing bars are arranged along the longitudinal direction of the steel frame 1 to reinforce the concrete P, if necessary.

(B) The next step is to launch the steel frame 1 configured as a box-shaped floating body as described above.

This steel frame 1 has a length that is divided into several parts of the marine structure, and the range in which the concrete P is poured is the extent that forms the floor surface in Fig. 1, and the partition wall 4 in Fig. The steel frame 1 is lightweight. Therefore, the steel frame 1 constituting such a box-shaped floating body can be easily launched into water by operating a normal crane or winch.

(C) As the next process, the steel frame 1
The purpose is to connect the two to form the substructure of an offshore structure.

Specifically, as shown in FIG. 4, frames 1, 1'...
The two are welded together underwater at sea to construct a floating body, which is the lower structure of the intended offshore structure. In this case, when the frames 1 and 1' are integrated, the steel side frames 2, 2' and the bottom plate 3 are welded together. The reinforcing bars are also joined together.

Since there is seawater between the partition walls 4 and 4' after welding as described above, drain this water and remove both partition walls 4.
Filler concrete Q is placed between 4', and concrete P is placed along the bottom plate 3 and the side frame 2 reaching above the water line WL.

By the above-mentioned work, a concrete wall is formed on the bottom plate 3 and a part of the side frame 2, and a large floating body 7a is constructed on the ocean. This floating body 7a constitutes the lower structure of the marine structure.

(D) In the next step, as shown in FIG. 5, the formwork 8 is extended above the side frame 2 of the floating body 7.

Of course, this work will be carried out at sea.
In this case, reinforcing bars are placed inside the side frames 2, 2 to reinforce the concrete. The formwork 8
Since the material protrudes above the water surface and serves to support the concrete, steel is suitable, but plywood used as ordinary formwork may also be used. In this step, the formwork 8 constituting the upper structure is formed.

(E) Next, as shown in Fig. 6, concrete P is poured into the inside of the formwork 8 and at predetermined parts of the frame of the substructure 7a, and after curing, the formwork 8 is removed to form a large-sized concrete. marine structures 7 can be constructed.

Note that the side frame 3 and the bottom plate 3 that constitute the lower structure 7a
The bulkhead 4 is integrated with the constructed marine structure 7, and remains in the structure as a so-called waste frame or as a reinforcing member.

In order to strengthen the marine structure 7, prestressed concrete can be employed. In this case, as shown in Figure 7, sections 9 and 9 are opened at both ends of the floating body in the longitudinal direction, and these sections 9 are used to cure the poured concrete P for a predetermined period of time before removing the frame. . Then, a predetermined tension is applied to the PC steel wires 10 protruding from both ends of the concrete structure using jacks. After applying the prestress tension in this manner, the tensioned end portions are processed according to a conventional method, and then the section 9 is removed by gas cutting as required.

〔Effect of the invention〕

The construction method for constructing a concrete offshore structure according to the present invention at sea includes a bottom plate, a U-shaped side frame projecting from both sides of the bottom plate, and a space between the bottom plate and the side frame at both longitudinal ends. A step of forming a floating body with an upper opening on land by pouring concrete between at least the periphery of the bulkhead, the bottom plate, and both side frames of a steel frame body consisting of bulkheads provided at intervals. a step of launching the floating body and connecting a plurality of floating bodies on the ocean to form a lower structure; assembling a formwork on the plate structure and pouring concrete into the lower structure and the formwork; It consists of processes.

Therefore, rather than constructing a large concrete structure itself inside a dock or on a seawall and then launching this large concrete structure, the steel frame of the substructure, which is a part of it, is built on the dock. Since the vessel is built and launched inside the ship or on the seawall, there is no need for equipment such as large docks or large cranes, making launching work extremely easy.

In addition, a small steel frame is launched at sea, and these are connected at sea to form a lower structure consisting of a floating body of a predetermined length, and the upper structure is constructed based on this. Concrete offshore structures can be easily constructed at sea.

Therefore, as long as there is a quiet place on the ocean, it is possible to easily construct a concrete offshore structure even in a place where there is no large-scale, full-scale cargo handling equipment.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view showing a steel frame which is a divided body of the lower structure of a concrete marine structure according to the present invention, Fig. 2 is a schematic side view showing a partition wall portion of the steel frame, and Fig. 3 is its plan view. Fig. 4 is a perspective explanatory view showing the state in which the steel frame body is integrated to form a floating substructure, and Fig. 5 shows the state in which the formwork is extended above the substructure. The explanatory diagram, FIG. 6, is a schematic diagram showing a situation in which concrete is being poured into the space of a formwork, and FIG. 7 is an explanatory diagram showing a state in which an offshore structure using prestressed concrete is being constructed. 1...Steel frame body, 2...Side frame, 3...Bottom plate, 4
... Bulkhead, 7a... Substructure, 7... Marine structure (floating body).

Claims (1)

[Claims] 1 A steel frame body consisting of a bottom plate, side frames projecting in a U-shape from both sides of the bottom plate, and partition walls provided at both longitudinal ends with a gap between the bottom plate and the side frames. , a step of forming a floating body with an upper opening on land by pouring concrete between at least the peripheral surface of the bulkhead and the bottom plate and both side frames, and launching the floating body and launching a plurality of floating bodies on the ocean. A concrete marine structure is constructed offshore, which consists of the steps of connecting to form a substructure, raising a formwork for the superstructure on top of the substructure, and pouring concrete into the substructure and formwork. Construction method.