JP7374843B2 - Center formwork equipment and tunnel construction method - Google Patents

Description

The present invention relates to a center formwork device used for tunnel construction and a tunnel construction method using this center formwork device.

In recent years, power plants such as nuclear power plants and thermal power plants are required to take measures to protect their structures from external factors such as tornadoes and aircraft collisions. In line with this, when newly installing piping and cables to connect outdoor equipment to a power generation plant, it is necessary to use the conventional structure where they are installed overhead with supports provided on the ground surface, or to bury trenches shallowly below the ground surface. A structure in which the tunnel is installed and installed inside is no longer applicable, and a tunnel 10 or the like having a curved section 11 at the top and a flat floor section 12 at the bottom as shown in Fig. 5 is installed at a sufficient depth from the ground surface. However, a structure to install it inside is required.

When carrying out this tunnel construction, the center construction method is adopted in which a center using a center formwork device is used. In this center formwork device, the outer peripheral part of the formwork has a semi-cylindrical shape and is divided into a plurality of parts in the circumferential direction, and each part can be expanded and contracted individually. A plurality of small windows for concrete pouring that can be opened and closed from the inside of the center are provided on the surface of the center formwork device. The center can move forward and backward in the direction of extension of the tunnel 10 within the tunnel. For example, the center formwork device contracts in diameter when the center moves, and expands in diameter when pouring concrete.

Since mechanical and electrical equipment, etc. are provided inside the tunnel 10, it is necessary to install metal fittings on the inner wall of the tunnel in order to attach and support the mechanical and electrical equipment, etc.

When installing hardware in a general concrete building, the hardware is set up before concrete is poured, concrete is poured, and the hardware is buried within the concrete.

Japanese Patent Application Publication No. 2007-262674 Japanese Patent Application Publication No. 2017-166244 Japanese Patent Application Publication No. 2001-317293

When setting embedded metal fittings using the center construction method, the center formwork device of the center repeatedly expands and contracts in diameter when placing cement and moving the center, which reduces the accuracy of setting the embedded metal fittings that support mechanical and electrical equipment, etc. There was a possibility. In addition, because the filling pressure of concrete is high, the position of the embedded hardware may shift due to the flow of concrete, which may cause damage to the center formwork device or insufficient cover thickness of concrete. Regarding the former problem, Patent Document 2 discloses a method of solving the problem by using an elastic member to cope with the diameter expansion and diameter reduction of the center formwork device. Regarding the latter, Patent Document 1 discloses a method of fixing the embedded hardware from the inside of the tunnel by providing a small window for fixing the embedded hardware on the center side, thereby preventing movement of the embedded hardware.

However, when the diameter of the tunnel is small, structures such as reinforcing ribs are installed on the inner surface of the center, and there is no space to install a small window. It was not a technology that would solve the problem.

If it is not possible to embed metal fittings, it is necessary to post-cast the metal fittings after pouring the concrete in the tunnel, but in tunnels with small diameters where small windows cannot be installed, the curvature of the curved surface is small, and the work time involved in rebar exploration is reduced. This increases the cost of the process and its operations. Furthermore, since the metal fittings are set on the curved surface of the upper curvature portion, there is a problem in that a gap is created between the tunnel inner wall surface and the post-cast metal fittings, and the amount of work to fill the gap increases.

The center formwork device according to the above embodiment is a center formwork device that is installed across the tunnel inner space side from the tunnel inner wall surface toward the tunnel center side at a predetermined interval. The tunnel is characterized in that protrusions each having a flat surface having an area to be set for post-cast metal fittings are removably installed at regular intervals in the extending direction and/or up and down direction of the tunnel on the outer surface of the tunnel .

Further, in the tunnel construction method according to the above embodiment, reinforcing bars are arranged on the inner wall surface of the tunnel that has been excavated, and are placed at predetermined intervals from the inner wall surface of the tunnel toward the center of the tunnel. The center formwork device is installed across the sides, concrete is poured between the inner wall surface of the tunnel and the center formwork device, and after the concrete is poured, the center formwork device is formed by the protrusion of the center formwork device. The feature is that post-cast metal fittings are installed on the flat surface of the concrete wall.

Embodiments of the present invention have been made to solve the above-mentioned problems, and include flat surfaces arranged at equal intervals in the extending direction of the tunnel and/or in the vertical direction on the inner surface of the tunnel in the post-cast hardware setting section after concrete pouring. This makes it easier to set up post-cast metal parts.

FIG. 1 is a perspective view showing a center formwork apparatus according to the present invention. FIG. 1 is a sectional view of a tunnel structure after concrete placement using the center formwork apparatus according to the present invention. FIG. 2 is a cross-sectional view showing how hardware is installed in a tunnel using the center formwork device according to the present invention. The perspective view which shows the other Example of the center formwork apparatus based on this invention. FIG. 1 is a schematic perspective view showing a general tunnel structure.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on drawing.

Embodiments of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view showing a center formwork apparatus according to the present invention, FIG. 2 is a cross-sectional view of a tunnel structure after concrete placement using the center formwork apparatus according to the present invention, and FIG. 3 is a center type according to the present invention. FIG. 3 is a cross-sectional view showing how hardware is installed in a tunnel using a frame device.

In FIG. 1, in tunnel construction using a center, a center formwork device 1 is installed from the inner wall surface of a tunnel 6 toward the center of the tunnel at a predetermined interval, extending across the hollow side of the tunnel. On the outer surface of the center formwork device 1, a box-shaped protrusion 2 is removably installed, and the box-shaped protrusion 2 has a flat surface having an area for setting post-cast metal.

The protrusion 2 can be made of any material as long as it can withstand the pressure during concrete filling. The protrusions 2 are installed at equal intervals in the extension direction or the vertical direction of the tunnel 6, or in the extension direction and the vertical direction, and if the installation position of the post-cast metal fittings is specified in advance, the post-cast metal fittings are not set. The protrusion 2 at the position may be removed, and a closing member (not shown) may be installed at the portion where the protrusion 2 is removed. Although the protrusion 2 has been described as having a box shape, it is sufficient that a flat part having an area for setting the post-molded metal parts is formed on the outer surface, and it may be cylindrical, truncated pyramid, or truncated cone. Of course, it is also good.

In FIG. 2, as shown in the cross-sectional view of the tunnel structure after concrete pouring, reinforcing bars 3 are placed on the inner wall surface of the tunnel 6 that has been excavated. Concrete 4 is placed in the space formed by the wall surface and the center formwork device 1, and a planar portion, which is a tunnel box cutout portion 5, is formed on the concrete wall surface of the tunnel 6 by the projections 2 shown in FIG.

Then, as shown in FIG. 3, post-cast metal fittings 7 are placed in the tunnel box cutout part 5 where a flat part is formed on the upper curved surface of the concrete wall, up to the position of the reinforcing bars 3 without cutting the reinforcing bars 3, as in a general building. Place and configure.

Note that the size of the above-mentioned protrusions may be any size. For example, as in another embodiment shown in FIG. By setting the protrusion 9 where the post-cast metal fittings 7 can be set, reinforcing bar exploration can be performed all at once, and the setting of the post-cast metal fittings 7 can be further facilitated.

In addition, since it is a flat surface, for example, by scanning or photographing the reinforcing bars 3 placed in advance, interference of the reinforcing bars 3 can be prevented by projecting the placement information of the reinforcing bars 3 using a projector after pouring concrete. Cutting can be prevented and installation of the post-cast metal fittings 7 can be made easier.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention.

These embodiments can be implemented in various other forms, and various omissions, substitutions, changes, and combinations can be made without departing from the gist of the invention.

These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 1... Center formwork device, 2... Protrusion, 3... Rebar, 4... Concrete, 5... Tunnel box cutout part, 6... Tunnel, 7... Post-cast metal fittings, 8... Center formwork device, 9... Projection, 10 ...tunnel, 11...curvature section, 12...floor section.

Claims (6)

In a center formwork device that is installed across the hollow side of a tunnel at a predetermined interval from the inner wall surface of the tunnel toward the center of the tunnel,
On the outer surface of this center formwork device, protrusions each having a flat surface having an area for setting post-cast metal parts are removably installed at equal intervals in the extension direction of the tunnel and/or in the vertical direction. Center formwork equipment featuring: 2. The center formwork device according to claim 1, wherein the protrusion has a box shape, a cylindrical shape, a truncated pyramid shape, or a truncated cone shape. 3. The center formwork device according to claim 1 , wherein the protrusion is installed in a manner that allows the post-cast metal to be attached or removed depending on the position required. The centerpiece according to any one of claims 1 to 3 , wherein the flat surface formed on the outer surface of the protrusion is set to have a larger area than the post-beating hardware. Formwork equipment. Reinforcing bars are placed on the inner wall of the excavated tunnel,
The center formwork device according to any one of claims 1 to 4 is installed at a predetermined interval from the inner wall surface of the tunnel toward the center of the tunnel, extending over the inner cavity side of the tunnel,
pouring concrete between the inner wall surface of the tunnel and the center formwork device;
A tunnel construction method characterized by setting post-cast metal fittings on a flat surface of the concrete wall formed by the protrusion of the center formwork device after pouring the concrete. When setting the post-cast hardware, the reinforcing bar placement information is projected onto the inner surface of the tunnel using a projector, and the center formwork device is installed based on the projected reinforcing bar placement information. The tunnel construction method according to claim 5 .

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