JPH051878B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a box-cutting method for placing secondary lining concrete in tunnel construction and the like.

Conventional technology Inside a tunnel, places called boxes are installed every 50 to 60 meters to install evacuation exits, telephone boxes, fire hydrants, etc. In order to install such boxes, it is necessary to pour secondary lining concrete. It is necessary to remove the box.

Conventionally, as shown in Fig. 3, such a box-cutting method involves excavating the ground 1 in a concave shape according to the box-cutting position, or pouring the primary lining concrete 2 in a concave shape to make it waterproof. After the sheet 3 has been stretched, when placing the secondary lining concrete, a steel concrete formwork (center ) Inside of 4, build a box-cutting form (wooden or metal frame) 5 according to the size of the box, and place this on the ground 1.
Alternatively, it is fixed to the primary lining concrete 2 via a piece of wood 6, and further fixed to the center 4 if necessary, and then to the space between the ground 1 or the primary lining concrete 2, the center 4, and the formwork 5 for box cutting. A method is adopted in which concrete is poured and a secondary lining concrete 7 is cast, and finally the center 4 and the formwork 5 for box cutting are removed and a box is formed at the position where the formwork 5 is placed.

Problems to be Solved by the Invention However, the conventional box cutting method described above uses a plywood board or the like to fit the size of the box one by one on site.
It is necessary to make a formwork for box-cutting, which is troublesome to manufacture, and requires excessive effort to assemble the formwork for box-cutting inside the center and fix it to the ground or primary lining concrete. However, if the formwork for box punching is supported and fixed to the ground or primary lining concrete using wooden pieces, it may damage the waterproof sheet stretched over the ground or primary lining concrete, impairing the function of the waterproof sheet. There was a problem.

The present invention was made in view of the above circumstances, and is a box-cutting method that allows easy production and installation of a box-cutting form, eliminates the risk of damaging the tarpaulin sheet, and allows simple and reliable box-cutting work. The purpose is to provide

Means for Solving the Problems In order to achieve the above object, the present invention involves stretching and fixing a waterproof sheet to the surface of the ground or primary lining concrete, and then placing a concrete formwork at a predetermined distance from the waterproof sheet. At the same time, a box-cutting form is placed inside this concrete form, and a secondary lining concrete is cast between the waterproof sheet and the concrete form and box-cutting form, and then the concrete form and In a box-cutting method in which a box-cutting form is removed and a box space is formed at the position of the box-cutting form,
As the box-cutting form, a flexible rubber or plastic sheet formed into a hollow box shape is used, and this box-cutting form is fixed to the concrete form, and the secondary When pouring the lining concrete, pressurized gas or powder is introduced into the hollow part of the box-cutting form to maintain the shape of the box-cutting form under pressure from the secondary lining concrete. It is something.

Effects According to the box cutting method of the present invention, a box-shaped formwork with a hollow interior is formed from a flexible rubber or plastic sheet, and this is fixed to a concrete formwork. Various box-cutting formworks can be prepared to suit the shape and size of the box, and they are easy to manufacture.They are also easy to fix to concrete formwork, and the box-cutting formwork can be easily incorporated. In addition to this, there is no need to fix the box-cutting formwork to the ground or primary lining concrete, so there is no risk of damaging the waterproof sheet stretched there; Even if the formwork comes into contact with the waterproof sheet during installation, the formwork body is made of flexible rubber or plastic sheet, so the waterproof sheet will not be damaged. Furthermore, since the box-cutting form itself is formed into a box shape with a hollow part made of flexible rubber or plastic sheet, when the secondary lining concrete is poured, Although it cannot withstand the pressing force of concrete, in the present invention, pressurized gas or powder is introduced into the hollow part of the box-cutting form when placing the secondary lining concrete, thereby adding rigidity to the box-cutting form. , it can sufficiently withstand the pressing force of the secondary lining concrete, and therefore the secondary lining concrete can be placed reliably.

1 and 2 for one embodiment of the present invention.
This will be explained with reference to the figures.

Embodiment FIGS. 1 and 2 show a box-cutting form 11 used in the present invention. This form 11 is made of a flexible rubber or plastic sheet and has a hollow section inside. A box-shaped formwork body 1 having 12
3 and a rubber tube 14 disposed in contact with or bonded to the inside thereof, and each of the form body 13 and the rubber tube 14 has a hollow portion 1.
2, a pressurized gas or powder/granular material inlet 15,
16 are formed. Further, the formwork 11 has a fixing lug 17 protruding from the edge of the formwork body 13 on the fixed side of the iron concrete formwork (center) 4, and a bolt insertion hole 18 is provided at a predetermined location of the lug 17. is formed.

When box-cutting is performed using this box-cutting form 11, the form 11 is first fixed to the center 4 using bolts 19. Here, this center 4
An opening 19 is formed at a position corresponding to the introduction ports 15 and 16 of the formwork 11 and communicates with these introduction ports 15 and 16. Next, when placing the secondary lining concrete, a compressor or the like is used to inject pressurized gas or powder into the hollow part 12 of the formwork 11 through the opening 19 of the center 4 and the inlet ports 15 and 16 of the formwork 11.
The secondary lining concrete is placed in the formwork 11 with rigidity. In this case, after introducing the pressurized gas or the powder or granular material, the opening 19 and the inlet ports 15 and 16 are hermetically closed by a method such as plugging. Further, after placing the secondary lining concrete, it is preferable to remove pressurized gas or powder from the hollow portion 12 by suction or the like before removing the center 4 and the formwork 11. Note that the other operations are the same as those of the conventional box-cutting method, so the explanation thereof will be omitted.

Here, pressurized air is suitably used as the pressurized gas, and expanded polystyrene beads or the like are used as the powdery material. For fixing the formwork 11 to the center 4, an appropriate method can be adopted, such as attaching a magnet to the lug 17 or forming the lug 17 itself with a magnet and fixing it by magnetic force.

According to the box-cutting method described above, box-cutting forms of various shapes and sizes can be prepared in advance, and the desired formwork can be selected and used during construction, making it easy to center. Since it can be fixed, it is easy to arrange the formwork for box punching. In addition, since the formwork for box-cutting does not need to be fixed to the ground or the primary lining concrete, the waterproof sheet will not be damaged during installation, and furthermore, the formwork for box-cutting does not need to be fixed to the ground or the primary lining concrete. Since rigidity can be imparted, secondary lining concrete can be placed without any problem.

In the above-described embodiments, a rubber tube is provided within the form body, but in some cases, the rubber tube may be omitted, and other configurations may be modified in various ways without departing from the gist of the present invention. There is no problem.

Effects of the Invention As explained above, according to the present invention, it is possible to easily manufacture and install a box-cutting form, and the waterproof sheet is not damaged during installation, and the secondary lining is not damaged. Concrete can be placed and boxed easily and reliably.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a box-cutting form used in the present invention, Fig. 2 is a sectional view showing the same form fixed to a concrete form, and Fig. 3 explains a conventional box-cutting method. This is a cross-sectional view of a concrete formwork with a box-cutting form attached inside a tunnel. 1... Earth, 2... Primary lining concrete, 3
...Waterproof sheet, 4...Concrete formwork, 7...
... Secondary lining concrete, 11 ... Formwork for box cutting, 12 ... Hollow part, 13 ... Form body, 14 ...
...Rubber tube, 15, 16... Pressurized gas or powder/granular material inlet, 19... Opening.

Claims (1)

[Claims] 1. After a waterproof sheet is stretched and fixed on the ground or primary lining concrete surface, a concrete formwork is placed with a predetermined distance from it, and a box-cutting form is placed inside this concrete formwork. , Place a secondary lining concrete between the waterproof sheet and the concrete formwork and the box-cutting form, then remove the concrete formwork and the box-cutting form, and place the box-cutting form in the position where the box-cutting form is placed. In the box-cutting method for forming a space for a box, a hollow box-shaped interior made of a flexible rubber or plastic sheet is used as the box-cutting form, and the box-cutting form is While fixing to the concrete formwork,
When placing the secondary lining concrete, pressurized gas or powder is introduced into the hollow part of the box-cutting form to maintain the shape of the box-cutting form under pressure from the secondary lining concrete. A box-cutting method for tunnel construction, etc., characterized by the following.