JP5131557B2 - Segment joint structure - Google Patents

Description

  The present invention relates to a segment for constructing a tunnel lining body, and more particularly to a joint structure for connecting pieces in a concrete segment in the circumferential direction of the tunnel.

  As is well known, a shield tunnel constructed by the shield method is generally a circular cross section, but in the case of a road tunnel provided at a shallow depth, it may be a rectangular cross section. A shield tunnel with a rectangular cross-section by a rectangular segment is constructed.

The segments include concrete, steel, or a composite structure thereof. For example, as shown in Patent Document 1, prestress is applied to a circular segment made of concrete applied to a large section tunnel. The one introduced is also common.
This is because, after introducing prestress to each piece constituting the segment, each joint is connected to each other in the circumferential direction of the tunnel (segment joint) by introducing a tightening force according to prestress. The piece is fastened in a ring shape, and it is said that the prestress that is continuous in the circumferential direction can be introduced and the rigidity as the segment ring can be improved.
JP 2004-324140 A

  In the segment shown in Patent Document 1, a bolt fastening type joint, a cotter type joint, or a worm wheel type joint is used as a joint for fastening each piece with a fastening force equivalent to prestress. In such a joint, a sufficient tightening force may not always be obtained, and the structure may be too complicated, and a joint structure that can provide a simpler and sufficient tightening force is desired.

  The above is not only a case where prestress is introduced into a circular segment, but also a common problem when prestress is introduced into a joint portion of a rectangular segment.

In other words, normal circular segments are small in bending due to soil water pressure, and the axial force (compression force) is naturally generated in the segment due to the arch effect on soil water pressure, so the tensile force due to bending is canceled, so the member cross section is The structure is advantageous in that it is thin and does not place a large burden on the joint.
On the other hand, the rectangular segment generates a large bending moment in the center of the upper and lower floor slabs that support the soil pressure at the top of the tunnel and the ground reaction force at the bottom of the tunnel, and the soil pressure on the side walls is small when the depth is shallow. The axial force (compression force) transmitted to the upper and lower floor slabs that support the frame is small, and the tensile force generated by the bending moment cannot be canceled sufficiently depending on the axial force, so the rectangular segment is thicker than the circular segment In general, a large burden is generated on the joint.

  Therefore, especially when constructing a tunnel lining with a rectangular section using rectangular segments, it is advantageous to increase the axial force by introducing prestress at least at the joints of the pieces constituting the upper floor slab. Although it is thought that the overall rigidity can be secured and the thickness of the member can be reduced and the burden on the joint can be reduced, at present, an effective and appropriate method for introducing prestress to the joint of the rectangular segment Is not provided, and even if the joint structure in the circular segment as shown in Patent Document 1 is applied to the rectangular segment as it is, it does not solve the problem at all, and an effective improvement measure is required. is there.

  In view of the above circumstances, an object of the present invention is to provide an effective and appropriate joint structure that allows a sufficient prestress to be introduced into a joint part of a segment with a simple structure.

The invention according to claim 1 is a joint structure for connecting pieces in a concrete segment for constructing a tunnel lining body to each other in the circumferential direction of the tunnel, and a joint portion between both pieces to be connected. The two PC steel bars are arranged in an X-shaped crossing manner, and each PC steel bar is tensioned and both ends are fixed to both pieces. Both pieces are fastened with pre-stress introduced in the part, and the PC steel rod has screws formed on the outer peripheral surface, and nuts as fixing tools can be screwed to both ends thereof, and should be connected In the joint portion between the two pieces, there are two sheath tubes in which the pieces are assembled in a straight line continuously intersecting in an X shape and an opening is opened at the end surface in the tunnel axial direction of each piece. The PC steel rod is inserted into the sheath tube from the insertion port in a state where both pieces are assembled, and the PC steel rod inserted into the sheath tube at the distal end of the sheath tube A nut that is fixed by screwing the distal end of the tube is embedded, and is fixed to the proximal end of the PC steel rod inserted into the sheath tube outside the insertion opening that opens to the proximal end of the sheath tube. A nut as a tool is screwed, and the base end portion is fixed in a state where the PC steel bar is tensioned by the nut.

  According to the present invention, two PC steel bars are arranged in an X shape at the joint between the two pieces to be connected, and each PC steel bar is tensioned so that both ends thereof are connected to both. By fixing to the piece, sufficient prestress can be introduced into the joint portion by the PC steel rod, and the structure of the joint portion can be simplified.

  In particular, a nut is used as a fixing tool for fixing the both ends of the PC steel rod by forming a screw on the outer peripheral surface, and a sheath tube for inserting the PC steel rod and its distal end portion in each piece If the fixing tool for fixing is fixed in advance, the PC steel rod can be easily inserted into the sheath tube from the end face after the pieces are assembled, and the tip can be easily fixed. Appropriate and sufficient pre-stress can be introduced into the PC steel bar simply by attaching a nut as a fixing tool to the base end and tightening with a torque wrench, and the base end of the PC steel bar can be easily fixed. .

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
In this embodiment, for a tunnel having a rectangular cross section constructed by using a rectangular segment made of concrete, prestress is introduced into a joint portion of a flat plate piece which is an upper floor slab of the tunnel. It is.

  That is, the rectangular segment in the present embodiment includes a flat plate-like upper floor slab piece 1 arranged at the upper center of the tunnel cross section, a flat plate-like lower floor slab piece 2 arranged at the lower center of the tunnel cross section, and a tunnel. The four corner pieces 3 constituting the corners and the side walls are assembled into a rectangular cross-section as a whole to constitute the tunnel lining. In particular, the upper floor slab piece 1 is formed from the upper ground. Due to a large earth and water pressure acting, a large bending moment is applied such that it is bent toward the lower surface side (inner side of the tunnel), and accordingly, at the joint between the upper floor slab piece 1 and the corner pieces 3 connected to both sides thereof. Since this is a heavy burden, prestress is introduced into the joint and the axial force is increased to equal or less than the case of the circular segment. It is obtained so as to ensure the cross-sectional strength.

2A is a front view showing an assembled state of each piece in the present embodiment, FIG. 2B is a top view thereof, and FIG. 3 is an enlarged view of a portion III in FIG. FIG. 4 is an enlarged view of a portion IV in FIG. 2B (however, the state after the upper plate piece 1 and the corner piece 3 are connected).
As shown in these drawings, in the present embodiment, each piece is connected sequentially in the tunnel circumferential direction and the tunnel axial direction by inserting the connecting pin 5 into the pin hole 6 basically like a conventional segment. At the joint between the upper floor slab piece 1 and the corner piece 3 connected to both sides thereof, two PC steel rods 10 are arranged in an X-shaped crossing, and both pieces The PC steel rods 10 are fastened to each other, and the PC steel rods 10 are tensioned to fix both ends to both pieces, thereby introducing prestress into the joint portion.

Specifically, in this embodiment, a screw is formed on the outer peripheral surface of the PC steel bar 10, and the PC steel bar is used as a fixing tool 11 for fixing both ends of the PC steel bar 10 to each piece. A nut that can be screwed to 10 is used.
Moreover, in the joint part between both the pieces to be connected, as shown in FIGS. 3 to 4, the two sheaths are arranged so as to intersect with each other in a straight line shape with both pieces assembled. The tube 12 is embedded in advance in a state slightly shifted in the vertical direction.
A nut as a fixing tool 11 to which the tip of the PC steel rod 10 inserted into the sheath tube 12 is screwed and fixed is buried in the tip of the sheath tube 12 on the wellhead side, For this, an appropriate reinforcing bar 13 is preferably arranged.
The base end of the sheath tube 12 on the face side is opened as an insertion port for the PC steel rod 10 in the bolt box 14 formed by cutting out the end surface in the tunnel axial direction of each piece, and both pieces are assembled. In this state, the PC steel rod 10 can be inserted into each sheath tube 12 from the insertion port.

Therefore, in this embodiment, after assembling the upper floor slab piece 1 and the corner piece 3, the PC steel rod 10 is inserted from the insertion opening of the sheath tube 12 opened to the face side end surface of each piece, and the tip thereof is attached. By screwing the nut as the fixing tool 11 and screwing the nut as the fixing tool 11 to the base end of the PC steel rod 10 and tightening with a torque wrench, a desired prestress is introduced into the PC steel rod 10. It is possible to fix the base end portion of the PC steel rod 10 in the bolt box 14 by the fixing tool 11 as it is.
If necessary, a filler such as mortar may be injected into the sheath tube 12 through the injection tube 15 and cured as shown in FIG. Fill it up.

According to the joint structure of the present embodiment, not only can the upper floor slab piece 1 and the corner piece 3 to be connected to both sides thereof be securely fastened by the two PC steel bars 10 crossed in an X shape, Sufficient prestress can be introduced into the joint portion by tensioning and fixing these PC steel bars 10.
In particular, a screw is formed on the PC steel rod 10 and a nut is used as the fixing tool 11, and a sheath tube 12 and a nut as the fixing tool 11 for arranging and fixing the PC steel rod 10 at the joint are fixed in advance. By embedding in each piece, it is possible to easily insert the PC steel rod 10, tension it, and fix it. Therefore, it has a sufficiently simple structure and only a sufficiently simple operation. It is possible to introduce sufficient prestress to the joint without increasing labor costs.

Although the embodiment of the present invention has been described above, the above embodiment is merely a preferred example, and the present invention is not limited to the above embodiment.
For example, the above embodiment is an application example in the case where prestress is introduced only to the joint portion between the upper floor slab piece 1 and the corner pieces 3 on both sides thereof for a rectangular segment. The present invention can be similarly applied to a joint portion between pieces (for example, the lower floor slab piece 2 and the corner pieces 3 or the corner pieces 3).
Moreover, although it is realistic to apply the present invention to a rectangular segment as in the above embodiment, the present invention is not limited to this, and can be similarly applied to a joint portion between pieces in a circular segment. Furthermore, it can be suitably employed as a joint structure when connecting pieces introduced with pre-stress as shown in Patent Document 1.
In any case, in the present invention, two PC steel bars are inserted into the joint portion between both pieces to be connected from the end face side of each piece and arranged in an X-shaped state, and these PCs are arranged. It is only necessary to introduce prestress to the joint part by tensioning and fixing the steel bar. As a specific configuration for that purpose, a screw is formed on the outer peripheral surface of the PC steel bar and both ends thereof are fixed. A nut is used as a fixing tool for each piece, and a sheath tube for inserting a PC steel rod and a fixing tool for fixing the tip of the piece are embedded in advance in each piece. The steel rod can be easily inserted into the sheath tube and its tip can be fixed easily, and a nut as a fixing tool is attached to the base end of the PC steel rod and tightened with a torque wrench. And enough prestress May be possible introduction, the work process for assembling shapes and sizes of the segment to the extent that the number of pieces, the coupling structure of the piece to each other, the entire segment, and other appropriate designs without departing from the scope of the present invention Needless to say, it can be changed and applied.

FIG. 5 is a diagram illustrating an embodiment of the present invention and a state in which rectangular segments are assembled. It is a figure which shows the assembly state of a rectangular segment similarly. FIG. FIG. FIG.

Explanation of symbols

1 Upper floor slab piece 2 Lower floor slab piece 3 Corner piece 5 Connecting pin 6 Pin hole 10 PC steel bar 11 Fixing tool (nut)
12 Sheath tube 13 Reinforcement bar 14 Bolt box 15 Injection tube

Claims (1)

A joint structure for connecting pieces in a concrete segment for constructing a tunnel lining body in the circumferential direction of the tunnel,
Two PC steel bars are arranged in the X-shaped crossing at the joint between both pieces to be connected, and each PC steel bar is tensioned, and both ends are fixed to both pieces. By doing this, both pieces are fastened in a state where prestress is introduced to the joint by the PC steel bar ,
The PC steel rod has a screw formed on the outer peripheral surface, and a nut as a fixing tool can be screwed to both ends thereof,
In the joint portion between the two pieces to be connected, the two pieces that intersect with each other in a straight line shape in the state where the pieces are assembled and have an insertion opening opened at the end surface in the tunnel axial direction of each piece. A sheath tube is embedded, and the PC steel rod can be inserted into each sheath tube from the insertion port in a state in which both pieces are assembled.
The outer end of the insertion opening opened at the proximal end portion of the sheath tube is embedded in the distal end portion of the sheath tube with a nut to which the distal end portion of the PC steel rod inserted into the sheath tube is screwed and fixed. A nut as a fixing tool is screwed to the base end portion of the PC steel rod inserted into the sheath tube, and the base end portion is fixed in a state where the PC steel rod is tensioned by the nut. A segment joint structure characterized by

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