JPH0547686B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> This invention relates to a method of constructing an underwater reinforced concrete structure.

<Prior Art and Problems> Conventionally, methods for constructing underwater reinforced concrete structures such as bridge piers and abutments in oceans, rivers, lakes, etc., which are surrounded by water, generally include The method of placing underground reinforcing bars underwater and then pouring concrete with a high cement content underwater has been adopted because it is simple.

However, with this method, when building underwater, especially in seawater, the construction is carried out in a state that contains components that have a negative impact on reinforced concrete structures, such as salt in the seawater, making it difficult to construct high-quality reinforced concrete structures. It was hot.

In order to prevent such negative effects, for example, it is desirable to surround the site where a concrete structure is planned to be constructed with a liquid-tight cofferdam to exclude any water inside and perform construction in a dry state. In order to make the cofferdam reach the impermeable layer at the bottom of the water and ensure liquid tightness, it is not possible to use simple steel sheet piles, and the cost for temporary cofferdams is too high. It wasn't realistic.

This invention has been made in view of the above-mentioned problems, and its purpose is to have a relatively simple structure that can be easily constructed, and to
An object of the present invention is to provide a construction method that can easily obtain underwater reinforced concrete structures of stable quality.

<Means for Solving the Problems> The method for constructing an underwater reinforced concrete structure of the present invention has been made in order to achieve the above object, and is a method for constructing a reinforced concrete structure from the bottom of the water to above the water surface. a step of surrounding the frame with a frame; a step of replacing the water in the frame with a filling liquid containing clay and a polymer solution and having approximately the same specific gravity as the water surrounding the frame; and the replaced filling liquid. To construct a concrete structure without leaving a planned construction site surrounded by water in a dry state, consisting of the process of installing reinforcing bars and formwork inside and pouring concrete within the formwork. It is characterized by:

《Operation》 Reinforcing bars buried in concrete structures are placed in a filling liquid containing clay and polymer solution, eliminating direct contact with water and seawater.
For example, construction that contains harmful substances such as salt is completely prevented, corrosion of reinforcing bars is prevented, and adhesion between reinforcing bars and concrete is improved.
Stabilize and improve the quality of structures.

In addition, since the filling liquid containing clay and polymer solution has a specific gravity similar to that of the water to be replaced and the water around the outer periphery of the frame, the water pressure acting on the inside and outside of the frame is balanced. can be stabilized without being deeply ingrained in the water or seabed.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 4 are schematic vertical cross-sectional views showing an example of the method for constructing an underwater reinforced concrete structure according to the present invention in the order of steps.

In the construction method shown in FIG. 1, first, the planned construction site of the concrete structure to be constructed as shown in FIG. 1 is surrounded by, for example, steel sheet piles connected in sequence in the horizontal direction to form a frame 10.

The frame 10 is designed to reach above the water surface 14 from the underwater bottom surface 12, and the amount of penetration below the underwater bottom surface 12 does not need to reach the impermeable layer, but may be sufficient to ensure its self-supporting state.

When the formation of the frame 10 is completed, as shown in FIG. 2, the water in the frame 10 is replaced with the filling liquid 16.

The filling liquid 16 is made by adding a polymer solution that disperses clay such as C, M, C, and polyvinyl alcohol to a suspension of water such as clay such as bentonite. By adjusting these components, the specific gravity is made almost the same as that of the water in the frame 10 to be replaced.

For example, replacing the filling liquid 16 with water may be performed by replacing the filling liquid 16 with water.
The water is injected using a pressure pipe 18 set so that its tip is at the bottom 12 of the water, and the water inside the frame 10 is pumped out using a pump 20.

Here, since the specific gravity of the filling liquid 16 and water is almost equal, the filling liquid 16 discharged from the pressure pipe 18 is
In order to prevent dispersion in water or mixing with water, it is desirable to interpose a diffusion suppressing sheet 22 at the interface between the filling liquid 16 and water.

When the filling liquid 16 has been replaced with water, reinforcing bars 24 are installed in the filling liquid 16, as shown in FIG.

The reinforcing bars 24 may be assembled in advance, and may be installed at the same time by being engaged with a formwork 26 that defines the outer periphery of the structure.

After the installation of reinforcing bars 24 and formwork 26 is completed, the fourth
As shown in the figure, the concrete 2 into the formwork 26
8 injections are made.

Filling liquid 16 overflowing from pouring concrete 28 is recovered by pump P and reused.

When the concrete 28 has been cast and hardened, the formwork 26 is removed, the filling liquid 16 is recovered while being replaced with water, and the frame 10 is removed to complete the construction work.

Now, in the reinforced concrete structure constructed as described above, the reinforcing bars 24 are installed in the filling liquid 16, so that they do not come into direct contact with water containing harmful substances such as salt, and the filling liquid 1
6 does not have any adverse effect on the reinforcing bars 2 or the concrete 28, so corrosion of the reinforcing bars is prevented and adhesion between the reinforcing bars and concrete is improved, and the structure can be constructed in an environment almost equivalent to that in a dry state. and stable quality can be obtained.

In addition, since the filling liquid 16 is adjusted to have almost the same specific gravity as the water to be replaced, the pressure is balanced inside and outside the frame 10 when the water is replaced, so that the frame 10 does not have to be deeply embedded. , there is no need to create a strict liquid-tight state, and therefore construction becomes easier.

In addition, in the above embodiment, the case where the frame body 10 and the formwork 26 are used separately has been described, but the present invention is not limited to this. It is also possible to construct it by yourself.

<<Effects of the Invention>> As explained above in detail, according to the method for constructing an underwater reinforced concrete structure according to the present invention, it is possible to construct a strong cofferdam structure to keep a site where a reinforced concrete structure is planned to be constructed in a dry state. Installation of reinforcing bars, etc. and pouring of concrete in a filling solution containing clay and a polymer solution without the need for it, and while eliminating components in the water that adversely affect reinforced concrete structures, such as salt in seawater. By carrying out this work, we aim to prevent corrosion of the reinforcing bars and improve the adhesion between the reinforcing bars and concrete.
High quality underwater reinforced concrete structures can be constructed economically.

[Brief explanation of the drawing]

1 to 4 are longitudinal sectional views showing an embodiment of the present invention in the order of steps. 10...Frame body, 12...Underwater bottom surface, 14...Water surface, 16...Filling liquid, 24...Reinforcing bar, 26...Formwork.

Claims (1)

[Claims] 1. In a method of constructing a reinforced concrete structure constructed by pouring concrete underwater, there is a step of surrounding the planned construction site of the reinforced concrete structure with a frame that reaches from the underwater bottom to above the water surface, and a filling liquid containing clay and a polymer solution and having approximately the same specific gravity as the water surrounding the frame; installing reinforcing bars and a formwork in the replaced filling liquid; and A method for constructing an underwater reinforced concrete structure, which comprises the step of pouring concrete into a concrete structure, and is characterized in that the concrete structure is constructed without leaving a planned construction site surrounded by water in a dry state.