JPH0531606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a method of constructing a concrete wall, such as a continuous underground wall.

<Prior art> In the construction method of concrete walls, for example, when constructing a continuous underground wall, only non-expandable ordinary concrete made of ordinary Portland cement, blast furnace cement, etc. is generally used. and build the wall.

<Problems to be Solved by the Present Invention> The conventional concrete wall construction method described above has the following problems.

<B> When constructing a wall using only ordinary concrete that does not have expansive properties, as in the past, the wall may be damaged in the horizontal direction due to consolidation, subsidence, and shrinkage during hardening during concrete placement. Cracks may occur.

Therefore, there is a risk that the quality of the wall will deteriorate.

<B> A condition in which horizontal cracks are particularly likely to occur is when the trailing element 4 is driven between the leading elements 3, as shown in FIGS. 5 and 6.

That is, the left and right direction is the concrete part of the preceding element 3, the front and back direction is the ground 5, etc.
This is a case where the surrounding conditions of the concrete placement part of the trailing element 4 are different.

In such a case, the frictional resistance of the surface of the trailing element 4 in contact with the concrete is different, and the amount of settlement of each part is different, resulting in variations in stress, which makes cracks 41 more likely to occur. .

<C> Furthermore, since the trailing element 4 is cast after the concrete of the already completed leading elements 3 on both sides has hardened, there is a risk that defects such as gaps may occur at the joints of each element.

<Object of the present invention> The present invention was made to solve the above-mentioned problems, and provides a concrete wall that can prevent horizontal cracks from occurring in concrete walls and that can construct high-quality concrete walls. The purpose is to provide a method for building walls.

<Configuration of the Present Invention> An embodiment of the present invention will be described below with reference to the drawings.

In this example, a method for constructing a continuous underground wall, which is one aspect of a method for constructing a concrete wall, will be described as an example.

<B> Preparation for pouring concrete (Fig. 1) First, concrete is poured on the ground at predetermined intervals to construct the preceding element 3.

Next, the ground between the preceding elements 3 is excavated, a reinforcing bar cage 5 is erected, and then a tremie pipe 6 for underwater concrete placement is installed.

<B> Concrete pouring (Figures 1 and 2) After completion of concrete pouring preparations, the trailing element 4 is constructed between the leading elements 3.

The method is to alternately cast expanded concrete 1 and ordinary concrete 2 using a tremie pipe 6 and to raise them to a predetermined height.

The amount of expanded concrete 1 and ordinary concrete 2 to be placed is determined by taking into consideration the element spacing, wall thickness, etc.

Here, the ordinary concrete 2 used is one that has been conventionally used.

That is, it is a non-expandable concrete made of ordinary Portland cement, blast furnace cement, or the like.

<C> Expandable Concrete The expandable concrete 1 is made by adding an expandable material to the above-mentioned ordinary concrete 2 so that it gradually expands after being poured.

As the expanding material, for example, a foamed material such as aluminum powder, a reaction regulator, etc. can be used.

<D> Expansion of concrete (Figures 3 and 4) As described above, by alternately pouring expanded concrete 1 and ordinary concrete 2, even if ordinary concrete 2 consolidates, sinks, or shrinks, expanded concrete 1 is consolidation of ordinary concrete 2,
By expanding by the amount that has sunk and shrunk, the shrunken amount of the ordinary concrete 2 can be replenished and the occurrence of cracks can be prevented.

Further, by expanding the expanded concrete 1 to an amount greater than the amount that the ordinary concrete 2 has been consolidated, settled, and contracted, prestress can be generated within the concrete wall.

By generating prestress within the concrete wall in this way, shrinkage during or after concrete hardening can be canceled, and the occurrence of cracks can be prevented.

As shown in FIG. 4, the wall constructed as described above is of high quality and free from cracks.

Further, due to the expansion of the expanded concrete 1 toward the leading element 3 side, the joint portion between the trailing element 4 and the leading element 3 is also integrated, so that the entire wall can be constructed with a constant quality.

<Effects of the Present Invention> Since the present invention has been described above, the following effects can be expected.

<A> Previously, walls were constructed using only ordinary concrete that did not have expansive properties;
Horizontal cracks may occur in the wall due to consolidation during concrete placement, settlement, and shrinkage during hardening, which may lead to a decline in the quality of the wall.

In contrast, in the present invention, a wall is constructed by alternately pouring expandable concrete and ordinary concrete.

Therefore, even if consolidation, subsidence, contraction, etc. occur in the concrete, the expandable concrete expands by an amount commensurate with the contraction.

Therefore, the occurrence of cracks can be prevented, and the quality of the wall, including its water-stopping properties and strength, is improved.

<B> If the expanded concrete used in the present invention is expanded by more than the amount of contraction of ordinary concrete,
Prestress can be generated within the wall.

Therefore, the strength of the wall can be increased, and shrinkage after concrete hardening can be canceled, making it possible to construct a wall with high strength and high quality.

<C> Since the trailing element is cast after the concrete of the already completed preceding elements on both sides has hardened, conventionally, there is a risk that defects such as gaps may occur at the joints of each element.

However, in the present invention, as the expanded concrete expands toward the leading element, the joint part between the trailing element and the leading element becomes integrated, and a wall body of a certain quality with improved water-stopping properties, quality, etc. can be constructed. I can do it.

[Brief explanation of the drawing]

Figures 1 and 2: Explanatory diagram of one embodiment of the present invention, Figure 3
Figure: An explanatory diagram showing the expansion action. Figure 4: An explanatory diagram of the completed wall. Figures 5 and 6: An explanatory diagram of a conventional example.

Claims (1)

[Claims] 1. A method for constructing a concrete wall, in which ordinary concrete that does not have expandability and expandable concrete to which an expandable material has been added are alternately laminated and cast while both have not hardened yet. A method of constructing a concrete wall, which is characterized by: