JP3084123B2 - Box culvert manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a box culvert.

[0002]

Conventionally, in order to manufacture a box culvert having a rectangular cross section, there are a vertical type where a form is arranged vertically and concrete is poured and a flat type where a form is arranged horizontally. there were.

[0003] Vertical culverts are advantageous because box culverts having a large cross-sectional area have a wider driving surface and a smaller length ratio. Conversely, box culverts with a small cross-sectional area have a narrower punching surface and lower productivity,
Flat hit was advantageous. Further, a bevel box culvert 1 as shown in FIG. 4, that is, a hollow portion 2 having a rectangular cross section inside, a top plate 3 and a bottom plate 4 each having a right-angled trapezoid, and one end face being obliquely oblique ((a) It is difficult to make a box culvert vertically (Figure (b)), or an isosceles trapezoid and both ends are oblique (Figure (b)). It was manufactured in.

Conventionally, in order to manufacture a rectangular parallelepiped box culvert by flat striking, the mold 5 shown in FIG. 1 has been used. The formwork 5 comprises a rectangular parallelepiped outer frame 6 having an open upper surface and an inner frame 7 having a substantially U-shaped cross section having an open lower surface. Opening surfaces 8-1, 8- 2 are provided. Although this opening surface is effective for pouring concrete and finishing the upper surface of the top plate and the bottom plate, since it is a free surface opened to the upper surface, it tends to cause a decrease in the density of the concrete and a decrease in planar accuracy. On the other hand, a large cross-sectional force acts on the top and bottom plates of the box culvert, and it becomes a water channel surface. Therefore, high strength, high density, and high plane accuracy are required. Was required.

The present invention has been made in view of the above circumstances. The purpose is to produce a box culvert with a relatively small cross section or a box culvert at an angle with high productivity.The obtained box culvert is prestressed and has excellent strength, and the top plate and bottom plate are dense and flat. It is to propose a method of manufacturing a box culvert with excellent accuracy.

[0006]

According to a method for manufacturing a box culvert having a rectangular cross section, a mold having an opening at the top plate and bottom plate upper surfaces is arranged laterally and expanded into the mold. When concrete is injected and the concrete surface reaches the lower level of the inner frame
Stop the concrete injection with the
After touching the lower lid and fixing it to the inner frame,
Resume pouring and after concrete pouring is complete,
It is characterized in that the mold is closed by covering it with an upper lid in contact with the surface and fixing it to the outer frame, thereby restricting the expansion pressure of the concrete in the mold.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS This embodiment is shown in FIG.
A laterally oriented formwork 5 comprising a rectangular parallelepiped outer frame 6 and an inner frame 7 whose lower surface forms an opening surface 8-2 and has a substantially U-shaped cross section is used.

After the desired reinforcement is formed in the formwork 5 (not shown), expansive concrete 9 is poured from above the formwork.
When the concrete 9 reaches the lower level of the inner frame 7,
After rough finishing the surface of the concrete 9 on the upper surface of the bottom plate 4 facing the opening 8-2, the lower cover 10 is put in close contact with the surface, and the bolt 12 is fastened to fix it to the inner frame 7 (FIG. 2).

Subsequently, when the expandable concrete 9 is further poured and reaches the upper surface level of the top plate 3, the opening 8 is formed.
After roughening the surface of the concrete facing -1, the upper lid 11 is put in close contact with the surface, and bolts 12 are fastened to fix to the outer frame 6. (FIG. 3).

The upper cover 11 and the lower cover 1 are provided in the openings 8-1 and 8-2.
The expansible concrete 9 filled in the closed mold 5 with 0 is solidified while its expansion pressure is restricted in the mold.

The concrete 9 is in close contact with the inner surface of the form 5 and solidifies to form a surface with high density and high planar accuracy.
At the same time, the constrained expansion pressure is converted to compression prestress, and the reinforcing bars arranged are firmly fixed to the concrete and the prestress is introduced, and the corresponding compression force is introduced into the concrete . After the solidification of concrete is completed, the formwork is dismantled and demolded and box culvert 1
Is obtained.

[0012]

The method of manufacturing the box culvert has the above-described structure, and the formwork is arranged horizontally.
By pouring concrete from the top surface with a large area, even a box culvert having a small cross-sectional area can be manufactured with high productivity. Since the expansive concrete is used and its expansion pressure is restrained in the mold and solidified, the surfaces formed in contact with the mold surface, including the top and bottom plates, can have high density and high flatness. At the same time, the expansion pressure of the expansive concrete is converted into prestress and introduced, and the strength is improved.

As described above, according to this manufacturing method, a box culvert or oblique box culvert having a small cross-sectional area can be efficiently manufactured. The obtained box culvert has high strength, and the density and planar accuracy of the top plate and the bottom plate. And a proof stress capable of withstanding a large sectional stress can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of an oblique box culvert formwork according to an embodiment.

FIG. 2 is a cross-sectional view of a state in which concrete has been poured to the upper surface level of the bottom slab in the formwork and a lower lid has been put on.

FIG. 3 is a cross-sectional view of a state in which concrete has been poured to the upper surface level of the top slab in the form and the upper lid is covered.

FIG. 4 (a) is a plan view of a half-cut box culvert,
(b) is a plan view of the double bevel box culvert, and (c) is the A-
It is A sectional drawing.

[Explanation of symbols]

1 ... bevel box culvert, 2 ... hollow part, 3 ... top plate,
4 Bottom plate, 5 Form, 6 Outer frame, 7 Inner frame, 8 Opening, 9 Expansive concrete, 10 Lower cover, 11 Upper cover, 12 Bolt

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI E03F 3/04 E03F 3/04 A

Claims (1)

(57) [Claims] In a method for manufacturing a box culvert having a rectangular cross section, a formwork in which the top and bottom slab upper surfaces are open is arranged sideways, and expansive concrete is poured into the formwork so that the concrete surface has an inner frame. When the lower level is reached
Stop the concrete injection with the
After touching the lower lid and fixing it to the inner frame,
Resume pouring and after concrete pouring is complete,
A method for producing a box culvert, comprising: covering an upper cover in contact with a surface of the mold , fixing the outer cover to the outer frame, closing the form, and restraining the expansion pressure of the concrete within the form.