JP2002339439A - Culvert - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the disadvantage of a conventional culvert wherein rigidity is higher than that of banking, so that earth pressure in the vertical direction applied to the culvert becomes large. SOLUTION: In this culvert, a compressive and flexible covering such as foam polystyrene is provided in the periphery of the culvert.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a culvert, and more particularly to a culvert capable of reducing a vertically acting earth pressure and an amount of deformation acting directly under a high embankment of 50 m or more.

[0002]

2. Description of the Related Art A culvert (hereinafter referred to as a culvert) installed directly under a high embankment for roads or the like is vertically arranged by a shearing force of a surrounding ground acting on a mass just above the culvert as compared with a low embankment culvert. Since the directional action earth pressure increases, the wall thickness of the culvert must be increased. As a result, an increase in construction costs and an extension of the construction process are inevitable. Therefore, as shown in FIGS.
Arch culverts, 2) precast arch culverts, 3) tunnel method culverts, 4) earth pressure reduction box culverts, and other methods have been proposed and put to practical use.

[0003] The arch culvert shown in Fig. 4 is an arch-shaped cast-in-place reinforced concrete structure that can withstand the earth pressure and the overburden of the embankment.

The precast arch culvert shown in FIG. 5 has the same structure as the arch culvert. However, by precasting the members and joining the members with hinges, the members can be made thinner than cast-in-place concrete. .

In the tunnel method culvert shown in FIG. 6, an artificial ground with a cement stabilized soil is constructed at a planned culvert site, the embankment including this portion is first performed, and then the culvert position is tunnel-excavated. The artificial earth is borne by the earth pressure and the inner space is used as a culvert.

Further, in the earth pressure reducing box culvert shown in FIG. 7, a styrene foam is laid at the top end of the box.
It is intended to reduce earth pressure by forming a ground arch.

[0007]

However, the culverts shown in FIGS. 4 to 6 have a higher rigidity than the embankment, and as a result, the vertical earth pressure acting on the culvert increases. There is. That is, the vertical earth pressure coefficient α
Since (α = vertical earth pressure / (unit volume weight of soil × overburden thickness)) exceeds 1.0, there was a disadvantage that the wall thickness was excessive.

The earth pressure reducing box culvert shown in FIG. 7 has a styrene foam (EPS) block just above the culvert, and is the only structure that reduces the vertical earth pressure acting on the culvert by compressive deformation of the EPS. However, since the main purpose is to reduce the vertical earth pressure acting on the upper slab of the culvert, it is not assumed that the thickness of the culvert side wall and the lower slab is reduced.

[0009]

The culvert of the present invention is characterized by having a compressible and flexible coating.

[0010] The coating is a foamed styrene.

[0011] The coating is characterized in that it is a precast of styrofoam.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, the culvert 1 is covered with an EPS material 2 as shown in FIG.
PS material 2 is compressed and deformed, and Terzaggi (Te
rzaghi) to generate a ground arch according to the loose earth pressure theory, thereby setting α <1.0 and further reducing the generated sectional force in the culvert 1.

Concretely, as shown in FIG. 2, after excavating and shaping the ground 4, applying the spread sand 5, setting the culvert 1 and placing the EPS block 6, the embankment 3 is completed. To reduce the vertical earth pressure. A filler 8 such as sand is filled between the outer periphery of the culvert 1 and the EPS block 6. In addition, in order to improve the workability of the installation of the culvert 1 and the EPS block 6, in another embodiment of the present invention, as shown in FIG. Culvert + EPS ”product.

[0015]

Since the culvert of the present invention has the above-described structure, it is not necessary to increase the rigidity of the culvert with respect to the embankment by reducing the vertical earth pressure, and the culvert body can be made thinner. Therefore, there is a great advantage that the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a culvert according to the present invention.

FIG. 2 is an explanatory view of a method for installing a culvert according to the present invention.

FIG. 3 is an explanatory view of another installation method of the culvert according to the present invention.

FIG. 4 is an explanatory diagram of a conventional arch culvert.

FIG. 5 is an explanatory diagram of a conventional precast arch culvert.

FIG. 6 is an explanatory view of a conventional tunnel method culvert.

FIG. 7 is an explanatory view of a conventional earth pressure reducing box culvert.

[Explanation of symbols]

 1 Culvert 2 EPS material 3 Embankment 4 Ground 5 Spreading sand 6 blocks 7 EPS 8 Filling material such as sand

Claims (3)

[Claims] 1. A culvert having a compressible and flexible coating. 2. The culvert according to claim 1, wherein said coating is styrofoam. 3. The underdrain according to claim 1, wherein said coating is a precast cast of styrofoam.