JPH059948A - Reverse concrete construction method - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention can enhance the drainage effect of breathing water, and also enhance the drainage effect even when the bottom surface of the upper concrete is horizontal. It is an object of the present invention to provide a reverse construction method for concrete that can be reduced. [Structure] The present invention is a reverse construction method for constructing an underground structure by successively splicing concrete below the ground surface. By arranging, the water absorbing member 5 is arranged at least near the bottom height of the upper concrete 1 on the inner surface of the form 2, and the lower concrete is spliced into the form. is there.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse concrete construction method.

[0002]

2. Description of the Related Art A reverse construction method is a method of constructing an underground structure by successively splicing concrete below the ground surface. Conventionally, as shown in FIG. 5, a form 2 is placed below the upper concrete 1 that has been placed in advance by wrapping the upper part, and the lower concrete 3 is directly placed in the form 2 from the pouring port 21. There are a direct method of joining and a filling method of filling a filling mortar 4 in a space left in the lower part of the upper concrete 1 as shown in FIG.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
There are the following problems. That is, in the reverse construction method, expansive concrete is used to integrate the striking joint between the upper concrete 1 and the lower concrete 3, and at this time, conventionally, as shown in FIGS. As described above, the bottom surface 11 of the upper concrete 1 was inclined at about 15 °, and the breathing water was discharged from the pouring port 21 due to the expansion of the lower concrete 3. Therefore, since the bottom surface 11 is inclined, the formwork becomes complicated,
Moreover, the amount of formwork increases due to the installation of the pouring port, which is uneconomical.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can enhance the draining effect of breathing water, and the bottom surface of the upper concrete is horizontal. Similarly, it is an object of the present invention to provide a reverse construction method for concrete that can enhance the drainage effect and reduce the amount of formwork. That is, the present invention, in the reverse construction method of constructing the underground structure by sequentially splicing concrete below the ground surface, below the upper concrete that has been previously placed, the upper part is wrapped and the formwork is arranged, The reverse concrete construction method is characterized in that the water absorbing member is arranged at least near the height of the bottom surface of the upper concrete on the inner surface of this form, and the lower concrete is spliced into the form. In addition, in the reverse construction method in which underground structures are sequentially spliced below the ground surface, the upper concrete is placed in advance so that the bottom surface becomes horizontal, and the concrete is vertically struck on this upper concrete. The hole is penetrated, then below the upper concrete, the form is placed by wrapping the upper part, and on the inner surface of this form, the water absorbing member is arranged at least near the bottom height of the upper concrete, It is a reverse concrete construction method characterized by piling lower concrete in a formwork. Furthermore, in the above two methods, it is a reverse construction method of concrete in which a plurality of drainage holes are opened at least near the bottom height of the upper concrete of the formwork.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. <B> Pre-casting of upper concrete The present invention is a reverse-casting method for constructing an underground structure by successively splicing concrete below the ground surface. First,
Excavating the ground to assemble the formwork, as shown in Figs.
The upper concrete 1 is placed in advance so that the bottom surface 11 becomes horizontal. In the upper concrete 1, concrete placing holes 12 are vertically penetrated.

<B> Installation of Formwork Next, the formwork 2 is placed below the upper concrete 1 with the upper part wrapped. On the inner surface of this formwork 2, at least near the height of the bottom surface 11 of the upper concrete 1, the bottom surface 11
A water absorbing sheet 5 is attached continuously or intermittently in the horizontal direction. The water-absorbent sheet 5 is, for example, a water-permeable sheet or non-woven fabric woven of polyethylene fibers,
A polymer water-absorbing gel permeated is used. In addition,
In consideration of the quality improvement of concrete, the water absorbing sheet 5 may be evenly attached to the entire inner surface of the formwork 2. Further, if necessary, a plurality of drain holes 22 may be formed at least near the height of the bottom surface 11 of the upper concrete 1 of the formwork 2. With this drain hole 22, the breathing water absorbed in the water absorbing sheet 5 is drained to the outside, and can also be used as an air vent hole when pouring concrete.

<C> Concrete Casting Concrete is cast through the casting holes 12 of the upper concrete 1 and the lower concrete 3 is cast in the formwork 2. For the concrete or mortar to be poured, use is made of a mixture of ordinary aluminum powder or aluminum powder with controlled foaming, an expansive material, and a special admixture for suppressing breathing. When concrete is spliced below the lower concrete 3, the upper concrete 1
In the same manner as above, the bottom surface of the lower concrete 3 is placed horizontally, the placement hole is opened, the form is installed, and the same method as above is repeated.

[0008]

By pouring expansive concrete, the lower concrete 3 expands and presses against the bottom surface 11 of the upper concrete 1 to integrate the joints.
However, since breathing water is generated from the cast concrete, if the breathing water is not drained properly, the integration of the splicing joint between the upper concrete 1 and the lower concrete 3 will be impaired. According to the present invention, the generated breathing water can be forcibly absorbed by adhering the water absorbing sheet 5 at least in the vicinity of the splicing portion, and can be discharged to the outside through the drain holes 22 and the like. Therefore, the breathing water is drained well,
It is possible to secure the integration of the splicing portion and improve the performance of the splicing portion such as water shielding.

[0009]

[Embodiment 2] In the above-mentioned embodiment, the bottom surface 11 of the upper concrete 1 is horizontal, but as shown in FIGS. It is possible to obtain the same effect as above.
In addition, when the bottom surface 11 of the upper concrete 1 is horizontal or provided with an inclination, when placing the concrete by placing only the placing hole 12,
Either of the method of placing only the driving port 21 and the driving of placing the driving hole 12 and the driving port 21 together can be adopted.

[0010]

Since the present invention is as described above, the following effects can be obtained. <B> Breathing water generated at the splicing part of concrete can be forcibly absorbed by the water absorbing sheet and reliably drained. Therefore, even if the bottom surface of the poured concrete is horizontal, a good drainage effect can be obtained. Therefore, unlike the conventional case, it is not necessary to provide an inclined bottom surface to promote drainage, the amount of formwork can be reduced, and economic efficiency and workability can be improved.

<B> A good drainage effect can be obtained only by sticking the water absorbing sheet to the inner surface of the mold, and the labor of the work is hardly required.

<C> In addition to the conventional method of providing a pouring port that also serves as a drainage part in the formwork, a method of pouring concrete from a pouring hole formed in the upper concrete is also possible. Therefore, the structure of the formwork is simplified and economical.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an embodiment in which the bottom surface of the upper concrete is horizontal.

FIG. 2 is an explanatory diagram of an embodiment in which the bottom surface of the upper concrete is horizontal.

FIG. 3 is an explanatory diagram of an example in which the bottom surface of the upper concrete is inclined.

FIG. 4 is an explanatory view of an example in which the bottom surface of the upper concrete is inclined.

FIG. 5 is an explanatory diagram of a conventional direct method.

FIG. 6 is an explanatory diagram of a conventional filling method.

Claims (3)

[Claims] 1. In a reverse construction method for constructing an underground structure by successively splicing concrete below the ground surface, a form is arranged by wrapping the upper part below the previously placed upper concrete, A reverse concrete construction method characterized by placing a water absorbing member on the inner surface of the formwork at least near the height of the bottom of the upper concrete, and joining the lower concrete into the formwork. 2. In the reverse construction method for constructing an underground structure by successively splicing concrete below the ground surface, an upper concrete is pre-cast so that the bottom surface is horizontal, and the upper concrete is vertically The concrete pouring hole is pierced in the upper part of the concrete, then the form is placed under the upper concrete by wrapping the upper part. A reverse concrete construction method, which is characterized by placing and placing the lower concrete in the formwork. 3. The method for inversion of concrete according to claim 1 or 2, wherein a plurality of drain holes are provided at least near the height of the bottom surface of the upper concrete of the formwork.