JPH07119388A - Initial prestressing method to tunnel wall - Google Patents

Abstract

PURPOSE:To facilitate the arrangement of PC steel materials in the case prestress is led in a tunnel wall consisting of a plurality of segments by PC steel materials. CONSTITUTION:Guides 4a..., 4b... and 4c... are provided to the peripheral surface of a segment 1 of which a ring 2 is formed, those guides 4a..., 4b ...and 4c... are wound in the circumferential direction through PC steel materials 5, and such a state is maintained after the PC steel materials are pulled. The PC steel materials 5 are wound on the peripheral surface of the ring 2, so that the PC steel materials can be visually seen and are easy to arrange.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of introducing prestress into a tunnel wall body formed by connecting a large number of segments in order to improve the connecting strength between the segments.

[0002]

2. Description of the Related Art Usually, in order to introduce prestress into a tunnel wall with a PC steel material, a sheath tube is provided in each segment along the prestress introduction direction and so as to communicate with each other, and the sheath tube is inserted. This is done by holding the PC steel material in tension. As the prestress introduction direction, there are generally two kinds, that is, the circumferential direction and the axial direction (length direction).

[0003]

The above-mentioned method is to insert the PC steel material into the inside of the segment. In such a method, the sheath tube must be embedded in the segment with high accuracy. If the communication between the sheath tubes is uncertain at the time of connection, there are problems that it is difficult to insert the PC steel material, and the insertion state of the PC steel material cannot be visually observed.

The present invention has been made in view of the above circumstances, and solves the above problems by allowing a prestress to be reliably introduced into a tunnel wall by a segment and not allowing a sheath tube to be inserted into the segment. It is intended to provide a method for introducing prestress to a tunnel wall.

[0005]

The present invention has been made in order to achieve the above-mentioned object, and a guide is provided along the prestressing direction on the outer peripheral surface of a tunnel wall formed by a plurality of segments. It is characterized in that the PC steel material is inserted into the guide and pulled, and the pulled state is maintained. Further, both ends of the PC steel material are made to penetrate a part of the segment and drawn out to the inner peripheral surface side of the tunnel wall body,
Securing these both ends to the inner peripheral surface of the tunnel wall body.

[0006]

According to the present invention, prestress is introduced by pulling and holding the PC steel material arranged on the outer peripheral surface of the segment constituting the tunnel wall, so that it is not necessary to embed the sheath tube in the segment and the PC By visually observing the steel material, the PC steel material can be easily wound and the tension state can be easily checked. In addition, if both ends of the PC steel material are penetrated through a part of the segment and are drawn out to the inner peripheral surface side of the tunnel wall body, and these both end portions are fixed to the inner peripheral surface of the tunnel wall body, Pulling and fastening work can be performed from the inner peripheral side with a large space, improving workability.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 and FIG. 2 show a ring (tunnel wall body) 2 assembled by connecting a plurality of arcuate plate-shaped segments 1 in the circumferential direction (length direction), and connecting the rings 2 in the axial direction. The tunnel wall is constructed by going. The ring 2 in this case is composed of a plurality of segments 1 that form the main body of the ring 2 and a key segment 1a that is incorporated at the end when connecting.

A step 3 along the circumferential direction is formed at the end of each segment 1 on the coupling direction side of the ring 2, and the circumferential surface of this step 3 portion is lined up in the width direction of each segment 1. The guides 4a, 4b, 4c, which are a set of three,
A plurality of sets are provided at intervals in the circumferential direction. These guides 4a, 4b, 4c are embedded in each segment 1 with both ends of a U-shaped rebar being along the width direction of the segment 1, and in each set of guides 4a, 4b, 4c. Position (4a, 4a ..., 4b, 4b ..., 4
c, 4c ...) are lined up along the circumferential direction.

Guides 4a, 4a ...
The PC steel material 5 is inserted in 4b, 4b ..., 4c, 4c. The PC steel material 5 in this case is the ring 2
It is a PC steel wire compatible with. Guides 4a, 4a ... 4
, 4c, 4c, 4c, ..., and the three PC steel materials 5 that extend along the circumferential direction are, as shown in FIG.
From both ends of one segment 1, a sheath tube 6 embedded in the segment 1 is passed and drawn out to a recess 7 formed in the inner peripheral surface of the segment 1. Then, the PC steel material 5 is pulled by a predetermined load, and this tensioned state is fixed to the inner peripheral surface of the segment 1 by the fastening means (in this case, split wedge) 8 at both ends of the PC steel material 5 pulled out to the recess 7. It is held by being worn, which introduces prestress in the ring 2.

Next, the procedure of the method for introducing the prestress to the ring 2 as described above will be described. First, after connecting the segments 1 ... 1a to form the ring 2, the recess 7 is formed.
From the three PC steel materials 5 passed through the sheath tube 6 on one side to the outer peripheral surface of the ring 2, and these are sequentially guided by the guide 4a,
4a ... 4b, 4b ... 4c, 4c ... While being wound around the ring 2, the sheath tube 6 on the other side is pulled out to the recess 7. Next, after fixing one end of both ends of the PC steel material 5 in the recess 7 to the segment 1 in which the recess 7 is formed by the fastening means 8, a jack (not shown) set in the recess 7 or the like. By pulling the other end of the PC steel material 5 by the pulling means, the whole is pulled, and when a predetermined load is introduced, the other end is fastened to the segment 1 by the fastening means 8. Ring 2
Pre-stress in the circumferential direction is surely introduced into. In addition,
In the illustrated example, the number of the PC steel materials 5 is one per one roll, but a plurality of PC steel materials 5 may be connected by a connecting material such as a coupler that can be tightened.

According to the prestressing method of this embodiment, the PC steel material is wound on the outer peripheral surface of the other segments 1 except the segment 1 for pulling out to the inner peripheral surface side through the PC steel material 5. Since it is configured, it is not necessary to bury the sheath tube. Therefore, it is possible to eliminate the trouble of burying the sheath tube in the segment 1 with high precision, and to solve the problem that the buried sheath tubes are not surely communicated with each other and it is difficult to insert the PC steel material 5. Further, by winding the PC steel material 5 around the outer peripheral surface of the ring 2, the PC steel material 5 can be visually observed, so that the PC steel material 5 can be easily wound and the tension state can be easily checked.

Further, both ends of the PC steel material 5 are connected to the segments 1
By penetrating into the recess 7 on the inner peripheral surface side,
The work of pulling and fastening the PC steel material by the pulling means can be performed from the inner peripheral surface side of the ring 2 having a wide space, and the workability is improved. It should be noted that the recess 7 needs a cross-section loss because it secures a space for tensioning the PC steel material 5, but when the loss becomes large, it is conceivable to use a segment made of steel or ductile. Also, as the recess,
As shown in FIG. 3, two recesses 7 are formed on the inner peripheral surface of one segment 1 and are offset from each other in the width direction.
Alternatively, the ends of the PC steel material 5 may be pulled out.

FIG. 4 schematically shows another embodiment of the invention, in which hexagonal segments 11 are connected to form a ring 12 which is slightly offset in the axial direction.
The PC steel material 5 is spirally wound around the outer peripheral surface of the tunnel wall body 13 formed by further connecting 2 in the axial direction, and the PC steel material is pulled to introduce prestress to the tunnel wall body 13. The PC steel material 5 intersects the joint 14 of the joint surface on the hypotenuse side of each segment 11. In the illustrated example, the number of the PC steel materials 5 is one, but the plurality of PC steel materials 5 are spirally formed so that the PC steel materials 5 intersect with all the joints 14 of the joint surface on the hypotenuse side in accordance with the pitch of the segments 11 in the axial direction. It is preferable to wind.

[0014]

As described above, according to the method of introducing prestress into a tunnel wall of the present invention, a guide is provided along the prestress introduction direction on the outer peripheral surface of the tunnel wall by a plurality of segments, This guide is characterized by inserting the PC steel material into this guide and pulling it, and maintaining this tension state. This saves the labor of accurately burying the sheath tube in the segment, and allows the buried sheath tubes to communicate with each other. The conventional problems such as uncertainties and difficulty in inserting the PC steel material are solved all at once, and the PC steel material can be visually arranged so that the PC steel material can be easily arranged and the tension state can be easily checked. Further, if both ends of the PC steel material are penetrated through a part of the segment and are drawn out to the inner peripheral surface side of the tunnel wall body, and these both end portions are fixed to the inner peripheral surface of the tunnel wall body, the PC steel material The work of pulling and fastening can be performed from the inner peripheral surface side of the tunnel wall with a large space, and the workability is improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional front view of a ring (tunnel wall body) to which prestress is introduced according to an embodiment of the present invention.

FIG. 2 is a perspective view of the same portion.

FIG. 3 is another modification of the fastening mode of the PC steel material.

FIG. 4 is a side view of another embodiment of the present invention.

[Explanation of symbols]

1, 1a ... Segment, 2 ... Ring (tunnel wall),
4a, 4b, 4c ... Guide, 5 ... PC steel material, 7 ... Recess,
8 ... Means of fastening.

Claims (2)

[Claims] 1. A method for introducing prestress into a tubular tunnel wall body in which a plurality of arcuate plate-shaped segments are circumferentially connected to form a ring and the rings are axially connected to each other. A guide is provided along the prestress introduction direction on the outer peripheral surface of the segment that constitutes the structure, and a PC steel material is inserted through this guide to pull it, and this tensioned state is maintained. How to introduce stress. 2. The end portions of the PC steel material are penetrated through a part of the segment and drawn out to the inner peripheral surface side of the tunnel wall body, and these both end portions are fixed to the inner peripheral surface of the tunnel wall body. Method of introducing prestress to tunnel wall.