JPH04136336A - Prestress introduction method for box segment - Google Patents

Abstract

PURPOSE:To enable tension to be easily applied by burying a PC steel material along a line between both corners of a square section box segment under assembly, temporarily tensioning the material and finally tensioning the material with prestressing members at the corners of the segment. CONSTITUTION:When concrete segments 1 and 2 having an approximately L-section form are assembled into a square cylinder to form a box segment 3, a PC steel material is buried between both corners of the segment 3 along the side thereof, and tensioned with a joint fitting 10. Also, prestressing members 11 are laid at the inside of the corners of each segment 1 and 2. After the PC steel material 6 is temporarily tensioned, both ends thereof are externally pushed with the aforesaid members 11, thereby tensioning the PC steel material 6. According to the aforesaid construction, a prestressing work can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for prestressing hox segments, which is suitable for use in constructing sewers, public ditches, underground passages, and the like.

[Prior Art] Concrete culverts, which are generally used when constructing sewers, public ditches, underground passages, etc., are formed into a rectangular tube shape with openings at both ends, and joints provided at each opening at both ends. It is a structure that connects sequentially using .

[Problems to be Solved by the Invention] By the way, because the hox-shaped culvert has a box-like shape, the space utilization rate is extremely high compared to the circular sold tunnel. For tunnels of such depth, when comparing a circular cross section and a box cross section designed under the same civil engineering conditions, the circular cross section has a lower space utilization rate and has the property of being more economical (lighter structure). For this reason, they have traditionally been installed in areas with shallow soil cover that could be achieved using open-cut construction methods.

Therefore, for deep tunnels such as those formed by the Nord construction method, circular segments are better.
It is economically advantageous because it has a lighter structure than box-type culverts, etc., which is why it is widely used.

The present invention has been made in view of these circumstances, and aims to make the box segment light in structure by applying axial force to the box segment, so that the box segment can be applied under the same civil engineering conditions as the circular segment. The purpose of this invention is to provide a method for introducing prestressing of box segments that enables the following.

[Means for Solving the Problems] The present invention provides a concrete segment that forms at least one side of the box segment when the concrete segments are assembled into a rectangular cylindrical shape to form a box segment having at least four corners. , pre-buried prestressing steel along one side of the box, and at the same time as each concrete segment was assembled, the joints of these prestressed steel were temporarily joined using a connector, and then at the corner of the box segment, Push the end of the PC steel material located at the corner to the outside and press the PCj
The solution was to tension the No. 14 material and apply prestress to the hox segments.

[Function] According to the method of introducing prestress into a box segment of the present invention, the ends of the PCM material are pushed outward at the corners of the box segment to apply tension to the PC steel material,
This tensions the PC steel, so P
Axial force is introduced into the CM material. Therefore, a high prestress is introduced into the hox segment, and a lightweight structure can be achieved.

[Example] Hereinafter, the method for introducing prestress into a box segment of the present invention will be explained in order of steps by showing an example and referring to FIG.

Four corner slabs 1, 1.2.2 including corner corners are used as concrete segments, and these corner slabs 1.1.
2.2 are joined into a substantially rectangular tube shape to form a concrete box segment 3.

Each corner plate part 1, 1, 2, 21 is bent into an abbreviated shape and has haunch surfaces 1a, la, 2a, 2a on the inner surface of the corner, and is later subjected to high tension. In consideration of the application, a 5RC (made of steel reinforced concrete) structure is used in advance. Also, 2 forming the top side
The two corner plates 1.1 each have a box cutout 4.4 at a position where the two are joined. In addition, two corner plate parts 1 forming these top sides
．． 1, a north pipe 5.5 extending in the span direction and opening into the box cutout 4.4 is buried in advance, and a PC steel material 6.6 is installed in each sheath pipe 5.5.
Insert. The PC steel material 6 is for providing a certain fixed stress state (prestress) as described later.

In addition, source tubes 5.5 extending in the respective span directions are embedded in the two corner plates 2, 2 forming the bottom side, similarly to the corner plates 1.1. 5
．． Insert the PC steel material 6.6 into each of the holes 5 and 5.

In addition, these corner version KI1. ! , 2.2, each corner of
A cylindrical simple jig 7.7.7.7 with openings on the haunch surfaces 1a, Ia, 2a, and 2a is buried. The cylindrical jig 7 used has a female screw part 8 on the inner surface of the end of the corner block part 12 facing the haunch surfaces 1a and 2a. Then, one end of the PC steel material 6 is released into the box cutout 4, and the other end is passed through the tube jig 7 and fixed to the corner plates 1 and 2 by an anchor plate 9.

Then, these corner plate portions 1.1 or 2.
2 are joined by aligning their respective box-cut portions 44, and the ends (U-shaped portions) of both PC steel materials 6, 6 are connected to the coupling tool (coupler 10) at the box-cut portions 44.
Continued by. The ends of the PC steel material 6 are threaded in advance, and the threaded portions are tightened into the coupler 10 to temporarily join the PC steel material 6.

Next, the prestress imparting member II is screwed into the simple jig 7 from the inner surface of the box segment 3 at the corners of both ends of the top side.

The prestress imparting member II has a male screw portion 12 that can be screwed into the female screw portion 8 of the simple jig 7, and is provided at one end of the male screw portion I2 to perform a screwing operation of the male screw portion 12. The PC steel material 6 is provided at the operation part 13 and the other end of the male screw part 12.
It has a push-in part 14 that pushes it outward. As shown in FIGS. 2 and 3, the pushing part 14 is
A groove portion 15 for taking in the PC steel material 6 is provided in the bottom portion of the groove.
It is provided extending in the diametrical direction of the bottom surface. The groove portion 15 is formed so that the depth gradually increases as it approaches both ends of the bottom surface portion in the diametrical direction.

The male screw portion 12 of such a prestress applying member 11 is screwed into the female screw portion 8 of the simple jig 7 at the corner of the corner plate portion 1. Pushing part 1 of prestressing member It
The PC steel material 6 is taken into the groove 15 provided on the bottom surface of the screw 2, and in this state, the degree of screw engagement between the male screw portion 12 and the female screw portion 8 is gradually deepened. Along with this, the PC steel material 6 is
It is gradually pushed outward inside the cylinder jig 7.

Next, in the same manner as described above, the prestress applying member 11 is screwed into the cylindrical jig 7 from the inner side of the hook safety member 3 at the corners of both ends of the bottom portion, thereby tightening the PCB material 6. Push outward.

According to the prestress introduction method of the Hox Sefmen 1 of this embodiment, the joints of the PC steel materials 6 and 6 buried in the corner sections 11, 2, and 2 are temporarily joined by the coupler 10. After that, the prestress applying member 11 is pushed in at the corner so that the prestress applying member 11 pushes the PC steel material 6 outward, so that the PC steel material 6 is given tension and becomes tense. . Therefore, an axial force is applied to the PC steel material 6, and a high prestress is introduced to the box segment 3.

Therefore, even in the case of a box-shaped segment, it is possible to provide an axial force as a generated cross-sectional force in the same way as in a circular segment, and it is possible to improve the resistance earth pressure. Therefore, the structure of the box segment 3 can be made light, and the economical efficiency can be improved. Since the Hox segment 3 has a rectangular box shape, its space utilization rate is originally high, and when this is taken into consideration, the improvement in economic efficiency is remarkable.

Furthermore, the magnitude of the axial force applied to the prestressing steel material 6 depends on the degree of tightening of the prestressing steel material 6 by the coupler IO and the degree to which the prestressing member 11 pushes the prestressing steel material 6, so that the desired stress can be achieved. By appropriately adjusting these according to the degree state (prestress), a box segment 3 having an arbitrary prestress can be obtained.

Next, another embodiment of the method of introducing prestress into a hox segment according to the present invention will be described with reference to FIG.

This embodiment differs from the previous embodiment mainly in the configuration of the push-in portion 14 of the prestressing member 11.

In this embodiment, the pushing part j of the prestressing member 11
4, a spherical hole anchor 14a is used.

Specifically, prior to forming the box segment 3,
Two corner sections 1.1 forming the top side and two corner sections 2.2 forming the bottom side of the hox segment 3
A pole anchor 14a is installed in each cylindrical jig 77 embedded in the
, 14a are respectively accommodated, and these corner plate parts 1
．． At the same time as embedding the PC steel material 6.6 into the pole anchor 14, the end of each PC steel material 66Jy:
a Fix it to 14a.

Each corner block 1.1 and corner block 22 are then joined to form the hox segment 3.

Thereafter, the prestress applying member 11 is screwed into the simple jig 7 at the corners of both ends of the top side of the box segment 3, so that the prestress applying member 11 pushes the pole anchor 14a outward. Then, the PC steel material 6 whose end is fixed to the pole anchor 14a
is pushed outward and tension is applied to it.

- Therefore, an axial force is applied to the PC steel material 6, and a high prestress is introduced to the box segment node 3.

Also, for the corners at both ends of the base, do the same as before,
Hole anchor 14 by prestressing member II
a to the outside, thereby tensioning the PC steel material 6.

As described above, according to the method for introducing prestress into the hox segment of the present embodiment, prestress is introduced into the box segment 3 as in the nN embodiments, and the structure of the hox segment 3 is made lighter, resulting in economic efficiency. will improve. In addition, since the spherical hole anchor 14a is used as the pushing part of the prestressing member 11, even if an axis misalignment occurs when pushing the prestressing member 11, the pole anchor 14a rotates as appropriate. This has the advantage that axis misalignment can be easily tolerated.

Note that the method of introducing prestress into a box segment of the present invention is not limited to the above-mentioned embodiments, and can be applied to
Specific configurations such as work procedures can be changed as appropriate during implementation.

For example, this method of introducing prestress into a box segment can be applied not only to the square cylindrical box segment 3 but also to other polygonal cylindrical segments.

Further, in the embodiment described above, the corner plate portion 1 forming the top side portion.
1 and the corner plate part 2.2 forming the bottom part.
An example was shown in which the steel materials 6, 6 were buried and prestressing members 11.11.11.11 were introduced at the four corners, but the PC steel materials 6 were buried in the corner sections 1. It may be provided only on the corner plate 2.2 forming the bottom side. In this case, the prestress applying members 11.11 may be introduced at two corners corresponding to both ends of the PCR material 6.

In addition to the shapes used in the above embodiments, the prestress applying member 11 may have other shapes as long as it is configured to tension the PC steel material 6 and apply axial force. It doesn't matter if it's from.

[Effects of the Invention] As explained hereinafter, according to the method for introducing prestress into a box segment of the present invention, after the joint portion of the PC steel material is temporarily tightened and joined using the connector, the PCw4 is applied at the corner of the box segment. Push the end of the material outward and press P.
Since tension is applied to the C steel material and thereby tensions the PC steel material, axial force is introduced into the PCM material.

Therefore, a high prestress is introduced into the hox segment, making it possible to achieve a lighter structure and improve economic efficiency.

In addition, the magnitude of the axial force applied to the PC9 material depends on the degree of temporary tightening of the PC steel material by the connector and the amount of pushing of the PC steel material, so it depends on the desired stress state (prestress). By adjusting these appropriately, a box segment having an arbitrary prestress can be obtained.

[Brief explanation of the drawing]

1 to 3 are for explaining an embodiment of the method of introducing prestress into a box segment according to the present invention. FIG. 1 is a sectional view of a box segment, and FIGS. FIG. 4 is a bottom view and a side view showing the structure of the pushing part of the stress applying member, respectively, and FIG. be. 1.2...corner section (concrete segment),
3...Hox segment, 6...PC111 material, 10...Coupler (connecting tool).

Claims (1)

[Claims] When assembling concrete segments into a rectangular tube shape to form a box segment having at least four corner corners, the concrete segment forming at least one side of the box segment is preliminarily provided with a corner. At the same time as each concrete segment is assembled, the joints of these PC steel materials are temporarily tightened using connectors, and then, at the corner of the box segment, the PC steel material located at the corner is buried. A method for introducing prestress into a box segment, the method comprising applying prestress to the box segment by pushing the end of the PC steel material outward.