JPH0442394Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a precast concrete roof girder lateral fastening joint roof for an under-base crossing structure or other underground structure that crosses under railroad tracks or under a road. It is.

[Conventional technology]

Conventionally, precast concrete roof girder (hereinafter referred to as this) is used for the roof of underground structures.
Pca roof girder) is JP-A-61-
As disclosed in Japanese Patent No. 95199, it is known that a circular hollow part is provided in the center of the girder cross section so as to extend over the entire length of the girder. A screw auger is inserted between this circular hollow part and a cutting edge fitted and connected to the tip of the Pca roof girder, and the screw auger excavates earth and sand, and the excavated earth and sand It is discharged through the circular hollow part. That is, the circular hollow portion is provided for inserting a screw auger and discharging excavated earth and sand.

In the underground structure that crosses under the roadbed shown in the above publication, the design span is the length in the direction perpendicular to the longitudinal direction of the Pca roof girder, that is, the length in the direction perpendicular to the cross direction of the underground structure that crosses under the roadbed. By adopting this method, horizontally tightened PC steel members extending in the direction perpendicular to the longitudinal direction of the girder, that is, in the girder width direction, are placed on the compression and tension edges of each Pca roof girder, and the Pca roof girder of the underground structure crossing under the roadbed is installed. is giving presto.

[The problem that the idea attempts to solve]

In the case of the Pca roof girder used in the above-mentioned conventional underground structure crossing under the roadbed, a circular hollow part is provided in the center of the girder cross section that extends over the entire length of the girder, so the roof girder extends in the width direction of the girder. The horizontal tightening hole provided in this way avoids the circular hollow part.
It must be installed on the compression edge side and the tension edge side of the Pca roof girder, and because it is not possible to arrange the horizontally tightened PC steel members in accordance with the distribution of bending moments acting on the girder cross section, that is, on the side where tensile stress occurs. Since it is not possible to place horizontally tightened PC steel, it is necessary to place equal amounts of horizontally tightened PC steel in a straight line on the compression edge and tension edge of the girder cross section, which results in an increase in the amount of horizontally tightened PC steel used. It is uneconomical.

On the other hand, according to the displacement press-in method published in Japanese Patent Publication No. 59-50000, it is not necessarily necessary to provide a circular hollow part that penetrates the girder in its longitudinal direction.

The purpose of this invention is to provide a Pca roof girder horizontally fastened joint roof for underground structures that can be economically constructed by rationally arranging horizontally fastened PC steel members.

[Means to solve the problem]

In order to achieve the above object, in the precast concrete roof girder horizontally fastened joint roof for an underground structure of this invention, a large number of Pca roof girders press-fitted into the ground are horizontally fastened and jointed by horizontally fastened PC steel members 1. In the roof of the constructed underground structure, each Pca roof girder is provided with a large number of hollow parts 2 extending in the girder width direction at intervals in the girder longitudinal direction, and between the hollow parts 2 adjacent in the girder longitudinal direction. , a horizontal tightening PC steel material 1 is inserted through each Pca roof girder, and the horizontal tightening PC steel material 1 is placed on the tension edge side of the Pca roof girder at the center side of the roof span, and also extends from the center side of the roof span to the tension edge side of the Pca roof girder. The horizontally tightened PC steel material 1 is arranged so that the amount of eccentricity gradually decreases toward both ends and into the core of the precast roof girder.

[Effect]

A horizontal tightening PC steel member 1 inserted across a large number of Pca roof girders is placed on the tension edge side of the Pca roof girder at the center side of the roof span, and is pre-strung from the center side of the roof span toward both ends of the roof span. Since the horizontally tightened PC steel material 1 is arranged so that the eccentricity gradually decreases up to the core of the cast roof girder, an eccentric prestress moment is generated by one horizontally tightened PC steel material 1, and each Pca Due to the load action on the roof girder, compressive stress due to prestress is generated on the side where tensile stress is generated (tensile edge), and tensile stress due to prestress is generated on the side where compressive stress is generated (compression edge) of each Pca roof girder. generate.

〔Example〕

Next, this invention will be explained in detail with reference to the drawings.

Figures 3 to 5 show a central Pca roof girder 3A used in an embodiment of this invention, in which a large number of hollow part forming cylindrical forms 5 into which end plates 4 are fitted and fixed are arranged. The cylindrical formwork 5 is buried so as to penetrate the precast concrete girder 6 in the girder width direction and at intervals in the girder longitudinal direction.
Hollow parts 2 extending in the width direction of the girder are formed in the girder material 6, and in the solid cross-section between the hollow parts 2 adjacent in the longitudinal direction of the girder and the solid cross-section between the girder end face and the hollow part 2 at the end. , a tension edge side horizontal tightening hole 7 extending in the width direction of the girder is provided on the tension edge side of the girder material 6,
Furthermore, reinforcing bars 8 extending in the longitudinal direction of the girder are buried in the corners of the girder cross section.

FIG. 6 shows Pca roof girders 3B and 3C that are arranged side by side in sequence on the side of the central Pca roof girder 3A, and are inclined diagonally upward in sequence from the level of the tension edge side horizontal tightening hole 7. Although inclined horizontal tightening holes 9 and 10 are provided, the other configuration is the same as that of the central Pca roof girder 3A.

The cross-sectional shape of the cylindrical formwork 5 is circular, square, or six.
It may be either rectangular or octagonal. Also end plate 4
The material of the cylindrical formwork 5 may be metal, wood, or plastic.

Figures 1 and 2 show the Pca roof girder 3A,
Regarding the embodiment of this invention using 3B and 3C
This shows an underground structure having a horizontally fastened joint roof with Pca roof girders, in which the roof of the underground structure crossing under the roadbed is the three central Pca roof girders 3A and the Pca roof arranged sequentially on both sides thereof. digit 3
B, 3C and the upper steel box girder 11, and the left and right side wall portions include a Pca side wall girder 12A located at the center in the vertical direction, and Pca side wall girders 12B and 12C arranged sequentially on both upper and lower sides thereof. and the lower steel box girder 13, and the Pca side wall girder 1
For 2A, 12B, 12C, Pca roof girder 3
The same structure as A, 3B, and 3C but with the orientation changed by 90° is used. In addition, each of the above Pca roof girders 3A,
3B, 3C and each Pca side wall girder 12A, 12B,
12C is press-fitted into the ground under the roadbed by a known displacement press-in construction method and crosses under the roadbed, and furthermore, the upper steel box girder 11 and the lower steel box girder 13 are inserted into the ground under the roadbed by a displacement press-in method or inside the box girder. A screw auger inserted into the hole removes the soil while it is press-fitted.

Pca roof girder 3 in the upper steel box girder 11
The Pca roof girder 3C is attached to the side plate 14 adjacent to C.
Horizontal tightening holes that match the inclined horizontal tightening holes 10 of the Horizontal tightening holes that match the tightening holes are provided, and rigidity reinforcing steel ribs 17 are fixed to each box girder 11, 13 by welding.

The tensile edge horizontal tightening holes 7 of each Pca roof girder 3A in the roof, the inclined horizontal tightening holes 9 and 10 of each Pca roof girder 3B and 3C, and the horizontal tightening holes in the side plate 14 of the upper steel box girder 11. Lateral tightening PC steel material 1 made of steel rod is inserted through the
The space between Pca roof girders 3A, 3B, 3C and
The space between the Pca roof girder 3C and the upper steel box girder 11 is filled with a hardenable filler 18 such as mortar.

After the filler material 18 reaches a predetermined strength, the anchor plate 19 and the fixing device 20 are set at the end of the horizontally tightened PC steel material 1 in the upper steel box girder 11, and the horizontally tightened PC steel material 1 is placed under tension. The end portion of the horizontally tightened PC steel material 1 is fixed to the side plate 14 via the anchor plate 19 by the fixing tool 20.

As for the side walls, each
Pca side wall girder 12A, 12B, 12C horizontal tightening hole, upper steel box girder 11 lower surface plate horizontal tightening hole and lower steel box girder 13 upper surface plate 16 horizontal tightening hole across the steel rod A horizontally tightened PC steel material 21 consisting of
Next, the space between each Pca side wall girder 12A, 12B, 12C and the space between the Pca side wall girder 12C and the upper steel box girder 1
1. A hardenable filler 18 is filled in the space between the lower steel box girder 13, and after the filler 18 reaches a predetermined strength, the horizontal tightening PC steel material 21 is tensioned, and the horizontal tightening is performed. The end of the PC steel material 21 is connected to the fixing tool 2
0 through the anchor plate 19 to the lower plate 15 of the upper steel box girder 11 and the lower steel box girder 13.
is fixed to the top plate 16 of the.

After the entire cross section surrounded by the roof and side walls is excavated, a concrete bottom slab 22 is poured, and the concrete bottom slab 22 and the lower steel box girder 13 are connected by anchor members 23.

7 and 8 show the Pca roof girder 3 used in conjunction, in which a truncated four-pyramidal protrusion 24 is integrally formed on one end surface of the precast concrete girder 6. , a truncated quadrangular pyramidal recess 25 that fits the protrusion 24 is formed on the other end surface of the beam 6, and on both end sides of the beam 6,
A hollow portion 27 is provided with slopes 26 for supporting the fixing metal fittings at the upper and lower portions, and circular arc-shaped holes 28 for threading screw rods that open at the upper and lower portions of the slopes 26 and the end faces of the girder are provided, and the vicinity of the slopes 26 is provided. The formwork 29 for molding is removed.

When connecting the Pca roof girders 3 shown in FIGS. 7 and 8, as shown in FIG. Arc-shaped hole 28 at the end of Pca roof girder 3
A connecting steel member 30 made of a steel circular arc-shaped screw rod having a straight male threaded portion at both ends is inserted through the connecting steel member 30, and a fixing fitting 31 is fitted to both ends of the connecting steel member 30, and a nut 32 is screwed into the connecting steel member 30. The tension member 33 screwed onto one end of the connecting steel member 30 is inserted into the hollow portion 27.
an engagement nut 3 inserted into a center hole jack 34 disposed inside and screwed onto the tension member 33;
5 to the hollow piston rod of the center hole jack 34, and with the connecting steel member 30 under tension by the center hole jack 34, tighten the nut 32.
After tightening, the center hole jack 34 and tension member 33 are removed.

Figures 10 and 11 show connected Pca roof girders. According to this connecting means, prestress is introduced into the connecting steel members 30 to integrate each Pca roof girder, so that one real piece of steel can withstand the effects of bending moment, shearing force, and torsional moment.
It exhibits the same behavior as the Pca roof girder.

The Pca roof girder shown in the above-mentioned Japanese Patent Application Laid-Open No. 61-95199 has a circular hollow part that penetrates in the longitudinal direction of the girder. If it is necessary to use connected girders, there is no simple, strong, and economical way to connect Pca roof girders.

However, the Pca roof girder used in this invention has a large number of hollow parts extending in the width direction of the girder and spaced apart in the longitudinal direction of the girder.
When using the ends of the roof girders connected, as described above, the center hole jack placed in the hollow part 27 of the end of each Pca roof girder is inserted into the connecting steel member 30 that is inserted across the end of each Pca roof girder. 34 allows a prestress to be introduced, so that the ends of the Pca roof girder can be firmly connected by simple means.

In the case of the above embodiment, the horizontal tightening PC steel material 1 extends diagonally upward in a straight line from the center side of the roof span to both ends of the roof span.
The horizontal tightening PC steel material 1 may be curved and extended diagonally upward in an arc shape from the center side of the roof span toward both ends of the roof span.

[Effect of idea]

This idea is structured as described above, so
This produces the effects described below.

Each Pca roof girder is provided with a large number of hollow parts 2 extending in the width direction of the girder at intervals in the longitudinal direction of the girder. The horizontally tightened PC steel members 1 are placed on the tension edge side of the Pca roof girder at the center side of the roof span, and are placed on the tension edge side of the Pca roof girder from the center side of the roof span toward both ends of the roof span. Since it is arranged so as to be inclined diagonally upward, it is possible to tighten the tension edge horizontally.
The PC steel material 1 generates compressive stress on the tensile edge of each Pca roof girder, and also generates tensile stress on the compressive edge of each Pca roof girder, so that the compressive stress on the compressive edge of the roof and the tensile stress on the tensile edge due to the load. Therefore, it is economical because the horizontal tightening of Pca roof girders can be rationally performed with less horizontal tightening PC steel material used.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional front view of an underground structure having a Pca roof girder horizontally fastened roof according to an embodiment of this invention, and Figure 2 is an enlarged view of the upper corner of the underground structure in Figure 1. 3 is a partial longitudinal side view of the Pca roof girder used in the embodiment of this invention, FIG. 4 is an enlarged sectional view taken along the line A-A in FIG. 3, and FIG. 5 is an enlarged sectional view of FIG. Figure 6 is a vertical front view showing the Pca roof girders arranged side by side on the side of the central Pca roof girder, and Figure 7 is one of the Pca roof girders used in conjunction. 8 is an enlarged sectional view taken along the line C-C in FIG. 7; FIG. 9 is a vertical sectional side view showing the state when the Pca roof girders shown in FIGS. 7 and 8 are connected; FIG. 10 is a longitudinal side view showing a state in which the Pca roof girders are connected, and FIG. 11 is a sectional view taken along the line DD in FIG. 10. In the figure, 1 is a horizontally tightened PC steel material, 2 is a hollow part,
3A, 3B, 3C are precast concrete roof girders (Pca roof girders), 4 is an end plate, 5 is a cylindrical formwork for forming a hollow part, 7 is a hole for tension edge side horizontal tightening, 9 and 10 are for inclined horizontal tightening Hole, 11 is upper steel box girder, 12A, 12B, 12C are Pca side wall girder, 13
is the lower steel box girder, 18 is the filling material, 19 is the anchor plate, 20 is the fixing device, 21 is the side tightening PC steel material,
24 is a protrusion, 25 is a recess, 28 is an arcuate hole for screw insertion, 30 is a connecting steel material, 31 is a fixing fitting, 32
33 is a tension member, 34 is a center hole jack, and 35 is an engagement nut.

Claims (1)

[Scope of utility model registration request] In the roof of an underground structure constructed by horizontally tightening a large number of precast concrete roof girders press-fitted into the ground and laterally tightening them using PC steel materials 1, each precast concrete roof girder has a large number of precast concrete roof girders extending in the width direction of the girder. The hollow parts 2 are provided at intervals in the longitudinal direction of the girder, and the hollow parts 2 are adjacent to each other in the longitudinal direction of the girder.
In between, the horizontal tightening PC steel material 1 is inserted into each precast concrete roof girder, and the horizontal tightening
The PC steel material 1 is placed on the tension edge side of the precast concrete roof girder at the center side of the roof span, and the PC steel material is laterally tightened from the center side of the roof span toward both ends of the roof span to the core of the precast roof girder. A precast concrete roof girder horizontally fastened joint roof in an underground structure arranged so that the eccentricity of 1 is gradually reduced.