JPH07111066B2 - Box segment prestressing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a prestressing method for prestressing a box segment that is suitable for use in constructing a sewer, a common ditch, an underground passage, or the like.

[Prior Art] Generally, a concrete culvert used for constructing a sewer, a common ditch, an underpass, etc. is formed in a square tube shape with both ends open, and a joint provided at each end opening. It is a structure that is sequentially connected using.

[Problems to be Solved by the Invention] By the way, since the box-type culvert and the like have a box-like shape, the space utilization rate is extremely higher than that of a circular shield tunnel. In a tunnel with a depth similar to the construction method, comparing a circular section and a box section designed under the same civil engineering conditions, the circular section, which is inferior in space utilization, has the property of being more economical (light structure). Therefore, it has been conventionally installed in a place where the soil cover is shallow enough to allow the excavation method.

Therefore, in tunnels with a depth that is formed by the shield method, circular segments are economically advantageous because they have a lighter structure than box-type culverts, and are often used. It is the actual situation.

The present invention has been made in view of such circumstances, and aims to apply an axial force to the box segment to achieve a light structure, and to apply the box segment even under the same civil engineering conditions as the circular segment. It is an object of the present invention to provide a method for introducing prestress in a box segment that enables the above.

[Means for Solving the Problems] In the present invention, according to claim 1, after the concrete segments are assembled into a rectangular tubular shape to form a box segment having at least four corners, the box segment is formed from the inner surface side thereof. , PC steel material along the span direction of each concrete segment, spanning through the pin material located in the corner angle of the concrete segment, the both ends are temporarily fastened and joined with a connecting tool, and then at the corner angles of the bottom end As a solution means, the pin material located at the corner is slid outward to tension the PC steel material to prestress the box segment.

Further, in claim 2, when the concrete segments are assembled into a rectangular tubular shape to form a box segment having at least four corners, each concrete segment is preliminarily made of PC steel material along the span direction of each concrete segment. At the same time as embedding and assembling each concrete segment, the joints of these PC steel materials are temporarily tightened and joined by connecting tools, and then at the corners of both ends of the bottom, the PC steel material is pushed outward to tension the PC steel material. The solution was to prestress the box segment.

[Operation] According to the prestressing method for introducing a box segment according to claim 1 of the present invention, after the PC steel material is temporarily tightened by the connecting tool, the PC steel material is tensioned through the pin material at the corners of the bottom end. Since the PC steel is tensioned by this, axial force is applied to the PC steel due to the effects of both temporary tightening by the connector and tension of the PC steel, and high prestress is applied to the box segment. Will be introduced.

Furthermore, according to the method of introducing prestressing of a box segment according to claim 2, without using a pin material, the joint portion of the PC steel material embedded in advance in each concrete segment is temporarily tightened simultaneously with the formation of the box segment. Since they are joined, it is easy to attach the PC steel material to the box segment. Further, since the PC steel material is tensioned by directly pushing the PC steel material without using the pin material, the prestress introduction operation to the box segment is easy.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to the drawings showing examples.

1 to 3 show a method for introducing prestress in a box segment described in claim 1.

First, the box segment 6 is formed by joining four types of concrete segments in a rectangular tube shape. The four types of concrete segments used at this time are
Top plate part 1, bottom plate part 2, both side plate parts 3, 3 and corner plate parts 4, 4, 5 including four corner parts. The bottom slab 2 has a box removing part 2a formed on the inner surface near the center thereof.
For the four corner plate portions 4, 4, 5 and 5, those which are bent in a substantially L shape and have haunch surfaces 4a, 4a, 5a and 5a on the inner surface side of the corners are used. In addition, these corner plate sections 4, 4, 5,
In consideration of applying high tension, an SRC (steel reinforced concrete) structure is used in advance.

In addition, concrete segments (top slab 1, bottom slab 2,
Both side slabs 3, 3 and corner slabs 4, 4, 5 and 5) have grooves 1b, 2b, 3b, extending in the respective span directions on their inner surfaces and substantially in the center in the width direction. 3b, 4b, 4b, 5b, 5b are formed in advance, and when the top plate portion 1, the bottom plate portion 2, both side plate portions 3, 3 and the corner plate portions 4, 4, 5, 5 are joined together, Grooves 1b, 2b, 3b, 3
b, 4b, 4b, 5b, 5b are continuously formed to obtain one ring-shaped groove 6b.

Then, a PC steel material 7 for giving a certain stress state (prestress) to the box segment 6 is embedded in the groove 6b.

Both ends of the PC steel material 7 are connected to the bottom plate portion 2 of the box segment 6.
At the box removing part 2a provided in the. By threading the both ends of the PC steel material 7 in advance, and tightening this threaded portion into the connector (coupler 8),
Temporarily tighten the PC steel material 7 and join it.

Next, the pin members 9 and 9 are inserted at positions along the inner surface of the PC steel material 7 at the corner angles of the corner plate portions 4 and 4 located on both sides of the top plate portion 1. The pin material 9 may be a round bar shape having a predetermined diameter or a pipe shape. Prior to inserting the pin material 9, a pin material insertion hole 10 penetrating in the width direction of the corner plate portion 4 is formed in advance at a predetermined position of the corner plate portion 4 to a size that allows rotation of the pin material 9. Form. Then, the pin material 9 is inserted into these holes 10.
The inner surface of the PC steel material 7 is pressed outward by inserting.

Next, at the corner angles of the corner plate portions 5, 5 located on both sides of the bottom plate portion 2, pin materials 11, 11 are inserted in the same manner as above,
As a result, the PC steel material 7 is pressed outward, but at this time, the pin material 11 is pushed into the corner plate 5a of the corner plate portion 5a.
Then, a prestressing member 12 for applying a prestress to the box segment 6 is attached by pressing the PC steel material 7 to the outside at right angles.

The prestressing member 12 has a bottomless cylindrical shape as shown in FIG. 3, and a trapezoidal female screw is formed on the inner surface thereof. Further, slits 13, 13 extending toward the other end surface are provided at both end portions in the diametrical direction of one end surface of the prestressing member 12. The width of the slit 13 is a width into which the PC steel material 7 can be inserted. Further, on the side surface of the prestressing member 12, there are provided elliptical holes 14 and 14 penetrating in a diameter direction orthogonal to the diameter direction in which the slits 13 and 13 are provided and through which the pin material 11 is loosely inserted. There is. The elliptical hole 14 has an elongated oval shape in the lengthwise direction of the prestressing member 12, and its major axis is dimensioned to allow the pin material 11 loosely inserted in the elliptical hole 14 to move to some extent. .

Then, the prestressing member 12 having such a shape is attached at the corner of the corner plate 5 in a state in which the length direction thereof is obliquely outward from the haunch surface 5a. At this time, the slits 13, 13 of the prestressing member 12
Insert the PC steel material 7 into the
The pin material 11 is inserted in the above, and the pin material 11 is attached so as to be almost in contact with the inner surface of the PC steel 7.

Further, a screw member 15 is fastened to the prestressing member 12 from the end facing the haunch surface side. Screw member 15
For this, one having a trapezoidal male screw on the outer surface is used. When tightening the screw member 15, a hydraulic unit of a shield machine (not shown) is used. Thus screw member
As the screw 15 is tightened, the tip of the screw member 15 is oblong hole 14,1
The pin material 11 inserted in the 4 is pushed outwardly, so that the pin material 11 pushes the PC steel material 7 outwardly and gives tension to the PC steel material 7. In this way, axial force is applied to the PC steel material 7,
Prestress is introduced into the box segment 6.
At this time, by appropriately adjusting the tightening amount of the screw member 15, it is possible to arbitrarily adjust the magnitude of the axial force applied to the PC steel material 7 and the magnitude of the prestress introduced into the box segment 6. is there.

As described above, according to the prestressing method for introducing the box segment of the present embodiment, after both ends of the PC steel material 7 are temporarily fastened and joined by the coupler 8, the corner plate portions 4, which are located on both sides of the top plate portion 1, At the corner angle of 4, the PC steel material 7 is bridged through the pin materials 9 and 9, and at the corner angles of the corner plate portions 5 and 5 located on both sides of the bottom plate portion 2, the prestressing member 12, 12
The pin materials 11 and 11 are tightened to the outer side orthogonal to the haunch surfaces 5a and 5a, and the PC steel material 7 is tensioned by the pin materials 11 and 11, so that axial force is applied to the PC steel material 7 and the box segment High prestress is introduced in 6. Therefore, even in the box segment 6, as in the case of the circular segment, it is possible to give an axial force as a generated sectional force, and it is possible to improve the resistance earth pressure. Therefore, the box segment 6 can be made lighter in structure, and the economy can be improved. Since the box segment 6 has a rectangular box shape, the space utilization rate is originally high, and if this is taken into consideration, the economic efficiency is remarkably improved.

The magnitude of the axial force applied to the PC steel material 7 depends on the degree of temporary tightening of both ends of the PC steel material 7 by the coupler 8 and the tightening amount of the PC steel material 7 by the prestressing member 12. Therefore, the box segment 6 having an arbitrary prestress can be obtained by appropriately adjusting these according to the desired stress level state (prestress).

Next, another embodiment of the box segment prestressing method according to claim 1 will be described with reference to FIG.

This embodiment is different from the above-mentioned embodiment mainly in the above-mentioned embodiment, as a concrete segment, a top slab 1, a bottom slab 2, both side slabs 3, 3 and a corner slab 4 including four corners. The point is that the box segment 6 is formed by using only the corner plate portions 4, 4, 5 and 5 including the four corner angles, while using 4, 4,5 and 5.

In addition, in the above-described embodiment, the corner angle of each corner plate portion 4, 4, 5 is 1
I showed an example in which pin materials 9, 9, 11, 11 were inserted in each book,
In this embodiment, as shown in FIG. 4, a plurality of pin materials (three in FIG. 4) are inserted. In this case, the prestressing members 12 and 12 are attached to the center pin member of the three pin members at the corners of the corner plate sections 5 and 5, and the pin members 11 and 11 are attached. This prestressing member 12,
Tighten with 12.

Next, claim 2 of the present invention will be described with reference to FIGS.

FIG. 5 shows an embodiment of a prestressing method for introducing a box segment according to claim 2.

This example is different from the example of the method for introducing prestress of the box segment according to claim 1 described above.
Mainly, when forming the box segment 6,
The point of using concrete segments (corner plates 4,4,5,5) in which PC steel materials 7,7,7,7 are embedded, and of PC steel materials 7,7,7,7 directly without using pin materials It is the point of tension.

Specifically, this example will be described in the order of steps. First, concrete segments are joined to form a box segment 6 having a rectangular tubular shape.

At this time, as the concrete segment, the corner slabs 4, 4, 5 including four corners are used.
In 4,4,5,5, sheath tubes 16,16,16,16 along the respective span directions are preliminarily provided on both ends of the corner slabs 4,4,5,5. It is used by embedding it in an open state in 17, 17, ... And inserting the PC steel materials 7,7,7,7 into the sheath tubes 16,16,16,16. Further, at the corner angles of the two corner plate portions 5, 5 forming the bottom of the box segment 6, there are used those in which cylindrical cylindrical jigs 18, 18 that open to the inner surface side are embedded. As the cylindrical jig 18, one having a female screw portion 19 on the inner surface of the end facing the inner surface of the box segment 6 is used.

And these concrete segments (corner plate 4,
4,5, 5) and box-out parts 17 and 17 of each other are put together, and in the box-out part 17, the ends (joint parts) of the respective PC steel materials 7 and 7 are connected by a coupler (coupler 8). Assemble into a square tube by temporarily tightening and joining.

Next, the prestressing member 20 is screwed into the tubular jig 18 from the inner surface side at the corner angles of both bottoms of the box segment 6.

As shown in FIGS. 6 and 7, this prestressing member 20 is provided at one end of the male screw portion 21 and the male screw portion 21 screwed to the female screw portion 19 of the tubular jig 18. It is configured to have an operation portion 22 for performing a screwing operation and a push-in portion 23 provided at the other end of the male screw portion 21 to push the PC steel material 7 outward. A groove portion 24 is formed on the end surface of the pushing portion 23 for taking in the PC steel material 7 at the corner of the box segment 6 and pushing it outward. The groove portion 24 extends in the diametrical direction of the pushing portion 23,
In addition, the depth is gradually increased toward both ends in the diametrical direction.

The male screw portion 21 of the prestressing member 20 is screwed into the female screw 19 of the cylindrical jig 18, and the PC is placed in the groove portion 24 provided in the pushing portion 23.
After the steel material 7 is taken in, the prestressing member 20 is gradually screwed in, and the depth of screwing of the male screw portion 21 and the female screw portion 19 is gradually increased. As a result, the PC steel material 7 is gradually pushed outward and given appropriate tension.

Thus, according to the box segment prestressing method of this embodiment, the box segments 6 are joined by joining the concrete segments (corner plates 4, 4, 5).
At the same time that the P is embedded in each corner plate 4, 4, 5, 5.
Since the C steel materials 7,7,7,7 are temporarily tightened and joined, and then the prestressing member 20 is pushed in to tension the PC steel material 7, an axial force is applied to the PC steel material 7, and the box segment 6 Prestress is introduced into. Therefore, similarly to the method of introducing prestressing of the box segment according to the first aspect, the box segment 6 can be made light in structure to improve the economical efficiency.

In addition, in this embodiment, the PC steel material 7 is embedded in advance in the concrete segment (corner plate portions 4, 4, 5, 5), and at the same time as joining the concrete segments, the PC steel material 7, 7,
Since the joint portions 7 and 7 are temporarily fastened and joined, the PC steel material 7 can be easily attached to the box segment 6 as compared with the method of introducing the prestress of the box segment according to the first aspect. Also, without using pin material, PC steel material 7
Since the PC steel material 7 is strained by pushing in,
The prestressing operation to the box segment 6 is very simple.

In addition, in this embodiment, the couplers 8,8,8,8 for temporarily tightening and joining the PC steel material 7 are provided at several places which are joints of the concrete segments (corner plate portions 4,4,5,5). Since they are respectively provided, the tension is introduced into the PC steel material 7 over the entire length of the PC steel material 7, and the prestress is introduced into the box segment 6 uniformly.

Incidentally, the prestressing method of the box segment of the present invention is not limited to the above embodiment, the shape and dimensions of each member,
Specific configurations such as work procedures can be appropriately changed in implementation.

For example, the prestressing method for introducing a box segment is not limited to the box segment 6 having a rectangular tubular shape, and can be applied to other polygonal tubular segments.

Further, in the above-mentioned embodiment, an example in which the prestressing members 12, 20 having a shape as shown in FIG. 3 or 6 and 7 is used is described. Any other shape may be used as long as it can apply force.

Further, the PC steel material 7 is not limited to one as shown in the above embodiment, and the number thereof can be increased according to a desired axial force.

[Effects of the Invention] As described above, according to the method of introducing prestress of a box segment according to claim 1 of the present invention, after joining the concrete segments to form the box segment, the PC steel material is connected by the connecting tool. Temporarily tightened, and at the corners at both ends of the bottom, tension is applied to the PC steel material through the pin material to tension the PC steel material, so axial force is applied to the PC steel material and high prestress is applied to the box segment. be introduced. Therefore, even in the box-shaped segment, as in the case of the circular segment, it is possible to give an axial force as the generated sectional force, and it is possible to improve the resistance earth pressure. Therefore, a lighter structure of the box segment can be achieved,
Its economic efficiency improves.

In addition, the magnitude of the axial force applied to the PC steel material depends on the degree of temporary tightening of the PC steel material by the connecting tool and the pushing amount of the pin material, so it depends on the target stress level (prestress). By appropriately adjusting these, a box segment having any prestress can be obtained.

Furthermore, according to the method for introducing prestressing of a box segment according to claim 2, when forming the box segment, a PC segment is directly used without using a concrete segment in which a PC segment is embedded in advance. Since it is pushed in to make it tense, it becomes easy to attach the PC steel to the box segment, and the pushing operation of the PC steel becomes very simple. It should be noted that the point that the effect of improving the economical efficiency by achieving a lighter structure of the box segment is obtained is similar to the method of introducing prestress of the box segment of claim 1 described above.

[Brief description of drawings]

1 to 3 are for explaining one embodiment of a method for introducing prestressing a box segment according to claim 1 of the present invention. FIG. 1 is a sectional view of the box segment, and FIG. Is a state diagram showing the bottom of the box segment as seen from the inner surface side, FIG. 3 is a perspective view showing the configuration of the prestressing member, and FIG. 4 is the prestress introduction of the box segment described in claim 1. FIG. 5 shows another embodiment of the method, and is a cross-sectional view of the box segment, and FIGS. 5 to 7 show one embodiment of the method of introducing prestressing of the box segment according to claim 2 of the present invention. Fig. 5 is a sectional view of the box segment,
6 and 7 are a bottom view and a side view, respectively, showing the configuration of the pushing portion of the prestressing member. 1 ... Top plate part (concrete segment), 2 ... Bottom plate part (concrete segment), 3 ... Side plate part (concrete segment), 4, 5 ... Corner plate part (concrete segment), 6 ... Box Segment, 7 ... PC steel material, 8 ... Coupler (connector), 9,11 ... Pin material, 1
2,20 …… Prestressing material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Taniguchi 1-7-1, Kyobashi, Chuo-ku, Tokyo Toda Construction Co., Ltd. (72) Inventor Masahiro Nakagawa 1-7-1, Kyobashi, Chuo-ku, Tokyo Toda Construction Co., Ltd. In ceremony company (72) Inventor Yuji Tategawa 1-7-1 Kyobashi, Chuo-ku, Tokyo Toda Construction Co., Ltd. (72) Inventor Makoto Jukagawa 1-7-1, Kyobashi, Chuo-ku, Tokyo Toda Construction Co., Ltd. Within

Claims (2)

[Claims] 1. A concrete segment is assembled into a rectangular cylinder to form a box segment having at least four corners, and a PS steel material along the span direction of each concrete segment is applied to the box segment from its inner surface side. , The concrete segment is hung through the pin material located at the corner, and both ends of the concrete segment are temporarily fastened and joined by a connecting tool, and then, at the corners of the bottom end, the pin material located at the corner is outward. A prestressing method for a box segment characterized by prestressing the box segment by sliding it to the side to tension the PC steel. 2. When assembling concrete segments into a square tube shape to form a box segment having at least four corners, each concrete segment is previously embedded with PC steel material along the span direction of each concrete segment. At the same time as assembling each concrete segment, the joint portions of these PC steel materials are temporarily fastened and joined with a connecting tool, and then, at the corner angles of the bottom end, the PC steel material is pushed outward to tension the PC steel material, A method for introducing prestress in a box segment, which comprises prestressing the box segment.