JPS62244921A - Construction work for concrete structure - Google Patents

Abstract

PURPOSE:To safely and exactly perform concreting work on sea by a method in which a foundation work is made on the seabed where a concrete structure is to be constructed, a steel caisson fabricated in factory is moored and landed on the foundation work, and concrete is orderly placed on the sea. CONSTITUTION:The seabed as a construction site is dredged, the surface soil is removed out, and a foundation 1 is constructed. A steel caisson 2 fabricated in factory is towed to construction site and settled on the foundation 1, and cement mortar is injected into the space between the foundation 1 and the caisson 2 for stabilization. Rubble 12 is charged to the surrounding of the caisson 2 and compacted. Formwork assembling for the ceiling slab of the caisson 2 and timbering are made, and the ceiling slab 14 is formed. Water in the caisson 2 is discharged to lower the level of water. Concreting work for side walls 15 is made to a given height to complete the structure. The construction work can thus be performed safely and exactly under dry condition.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a construction method for constructing concrete structures on the sea or under the sea. This relates to a construction method for concrete structures that is carried out in dry conditions.

[Prior Art] Conventionally, when constructing a concrete structure on the sea, as shown in Fig. 11, steel sheet piles a and b for earth retention are doubled and erected on the seabed C to provide a temporary cofferdam. The space between sheet piles a and b is filled in to create a built-up island d that protrudes into the sea. Next, excavation is performed within the steel sheet piles, groundwater is pumped up, concrete e is poured from the bottom, and concrete e is erected. Many raising methods have been adopted. f is the earth retaining shoring.

[Problems to be Solved by the Invention] However, the above conventional construction method has many problems as follows.

■ Large-scale construction work is required.

■ Earth retaining work using steel sheet piles is required, and submarine ground that can be piled or has adequate bearing capacity is required.

■ If the water is deep, the strength of the sheet piles will be insufficient.

■ The water pressure from the bottom becomes excessive, and a large amount of water springs up during excavation, making construction impossible.

■ There was a problem with the bedrock and stone PJ layer, which was difficult to close off with sheet piles due to the complicated seabed ground.

Therefore, the present invention provides L1! The purpose of the present invention is to provide a construction method for constructing a concrete structure by pouring concrete in a dry state without having to construct an island, build a base plate, and start up reconcrete.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides foundation work on the seabed at the location where the concrete 1 to structure is to be constructed,
After towing the steel-shelled caisson manufactured at the factory to the site, it is moored above the foundation on the seabed, and then water is passed through the m-shelled caisson to allow the steel-shelled caisson to land on the bottom. Concrete work is carried out in order from the caisson ceiling slab to the side walls, and each time the water in the rift is drained and lowered, and the concrete structure is completed by connecting it to the inner bottom of the caisson. be.

[Function] The foundation work on the seabed, the fabrication of the steel-shelled caisson, and the towing to the site are carried out separately, and the m-shelled caisson is sunk and landed on the bottom.
Therefore, concrete work can be carried out directly on top of the steel-shelled caisson, but this concrete work can be carried out at sea in dry conditions.This eliminates the need for underwater concrete work, and The frame material of the steel shell caisson becomes a composite member with concrete, and the steel frame and reinforced concrete can be used as a structure.

Example of implementation] Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows the state near the final stage of the construction process of a concrete structure using the construction method of the present invention, in which a steel shell caisson 2 manufactured in a factory is placed on a foundation 1 built underwater while water is flowing through it. After reaching the bottom, concrete work was carried out at sea starting from the ceiling slab of the caisson to lower the water level inside the caisson.
Next, concrete is poured for the side walls in stages, each time lowering the water level in the caisson and lowering the concrete.

To be more specific, FIGS. 2 to 10 specifically show the process order when implementing the construction method of the present invention up to FIG. 1. To explain according to this order, first, the concrete structure The seabed ground (soft rock) 3 at the location where the object is to be constructed is dredged and the topsoil 4 is removed (Figure 2), and then the foundation 1 is constructed. In this case, if the foundation 1 is a rubble foundation, it will be constructed as shown in Figure 3 (A), and if the foundation v11 is a shell foundation, it will be constructed as shown in Figure 3 g3).

Separately from the above-mentioned foundation 1 horizontal construction work on the seabed, in the present invention, t! After manufacturing the A-shell caisson, work will be done to tow it to the construction site.

The tjA shell caisson is manufactured in the shipbuilding dock 5 as shown in FIG. A box is made by assembling the shell material 6 and the frame material 7, concrete is poured into the bottom of the box to form the bottom concrete 8, and rising walls 9 are concreted on top of the bottom concrete 8 on the inner wall. A steel shell caisson 2 as shown in the figure is manufactured. Next, water is passed into the shipbuilding dock 5 to float the steel shell caisson 2! (Fig. 5) and towed from shipbuilding dock 5 to the site (Fig. 6).

The steel shell caisson 2 that was towed to the site is the steel shell caisson 2.
In order to position it above the foundation 1, which was constructed in parallel with the fabrication of the illll
A temporary support board 11 for installing the L-son 2 is installed on the foundation 1 (Fig. 7).

Next, water is passed through the steel shell caisson 2 to cause the lllll-son 2 to sink and land on the temporary support plate 11 on the foundation 1. After landing on the bottom, inject mortar into the gap between the foundation 1 and the bottom of the wA shell caisson 2 to stabilize the steel shell caisson 2 (
Figure 8). At this time, the water level is adjusted so that the external water pressure and internal water pressure to the steel shell caisson 2 are balanced, and excessive water pressure is not applied to the caisson 2.

When the steel shell caisson 20 has bottomed out, the rubble 12 is placed in the caisson 2.
At the same time, the pier 13 will be constructed to allow traffic from the land to the steel shell caisson 2 (Figure 9).

Once the above construction is completed, concrete work for steel shell caisson 2 will begin. In this concrete work, we first constructed the formwork for the caisson ceiling slab and shoring using the framework and beams of caisson 2 as supporting materials, and then used a marine concrete pump ship to construct the caisson ceiling slab. concrete is poured continuously to create the caisson ceiling slab 14 (Fig. 10). After the caisson ceiling slab has hardened, the water inside the caisson 2 is discharged in an amount corresponding to the concrete weight of the caisson ceiling slab 14 to lower the water level inside the caisson. Next, the formwork for the side wall and reinforcing steel work are carried out, and the concrete work for the side wall part 15 is carried out for the specified height of the side wall (Fig. 1). After the concrete has hardened, the water inside the caisson is drained using a pump to allow it to settle. , similar construction is carried out in the secondary, tertiary, and quaternary stages and lowered in sequence. ``V,R'' Finally, by connecting with the rising wall 9 in the caisson 2, the concrete 1~ structure is completed.

[Effects of the Invention] As described above, according to the concrete structure construction method of the present invention, a steel shell caisson is manufactured in a factory separately from the foundation work on the seabed, and the steel shell caisson is towed and transported to the site. After that, the tIA shell cooler is submerged and fixed, and then,
Since the concrete structure is constructed by performing concrete work on the sea and successively lowering it, the following excellent effects can be achieved.

(D) Construction can be done without preparing the island at sea, and there is less temporary construction work.

(fi) 1! ! Concrete work for the body can be carried out in dry conditions at sea, allowing for safe and reliable construction.

The caisson has a steel shell structure and can be completely watertight, making it possible to work safely inside the caisson.

(f) Submarine foundation work and tJA shell caisson fabrication work can be done simultaneously, shortening the construction period.

(V) The frame material of the steel shell can be made into a composite structure with reinforced concrete, reducing the need for reinforcing steel work.

・D: There is little influence of earth pressure and water pressure during construction.

[Brief explanation of drawings]

Figure 1 shows a construction site 1 constructed using the construction method of the present invention.
2 to 10 are explanatory diagrams showing the order of the construction process according to the method of the present invention. FIG. 1 is the foundation, 2 is the WA steel shell caisson 5 is the shipbuilding dock, 8 is the concrete base, and 13 is the pier.

Claims (1)

[Claims] 1) Foundation work is carried out on the seabed at the location where the concrete structure is to be constructed, and the steel shell caisson manufactured at the factory is towed to the site, moored above the foundation on the seabed, and then passed through the steel shell caisson. The steel shell caisson is then placed on the bottom with water, and then concrete work is carried out at sea from the caisson ceiling slab to the side walls, draining the water inside the caisson and lowering it each time, and connecting it to the inner bottom of the caisson. A method of constructing a concrete structure, which is characterized by completing the concrete structure.