JP2011219972A - Lining body and corner segment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a corner segment preventing the decrease in yield strength even if an inside pressure acts on a corner of a lining body and a lining body provided with this corner segment.SOLUTION: A lining body 2 is constructed in a nearly rectangular shape by assembling a multiple number of segments 3 made of reinforced concrete. Assembling of the segments 3 is performed in the tail portion of a shield machine. A nearly L-shaped corner segment 3a arranged at each corner 2a of the lining body 2 is composed of concrete 6, and a plurality of inside main reinforcements 4 and an outside main reinforcement 5 are provided inside the corner segment 3a. The inside main reinforcements 4 are disposed in such a manner that the near end parts of two neighboring inside main reinforcements 4 cross each other at the corner 2a.

Description

  The present invention relates to a lining body formed by assembling a plurality of reinforced concrete segments in a tunnel and a corner segment thereof.

  Conventionally, in the shield method, the lining body is constructed by assembling the segments at the tail of the shield machine.

  For example, Patent Document 1 discloses a reinforced concrete segment in which an inner main reinforcing bar is embedded at a predetermined depth position from an inner peripheral surface. Thereby, the tensile strength of a segment can be raised.

JP 2002-121999 A

  However, as shown in FIG. 10, when a bending moment M (inner tension) due to the influence of an earthquake or the like acts on a lining body constructed by assembling the above-described reinforced concrete segments into a substantially polygonal shape, the inner main reinforcing bars , Tensile forces T1 and T2 are generated in the axial direction of the substantially linear portion corresponding to the side, and a force T (hereinafter referred to as abdominal pressure) toward the inside of the tunnel is generated as a resultant force. Since only the tensile resistance TC of concrete resists the abdominal pressure T, a crack C is generated. When the abdominal pressure T increases, the crack C develops, and when the abdominal pressure T exceeds the limit of the tensile resistance TC of the concrete, the inner main reinforcing bar behaves to protrude inside the tunnel as indicated by a virtual line. As a result, there is a problem that the yield strength may be reduced due to damage to the corners before reaching the yield strength possessed by the substantially straight portion.

  Therefore, the present invention has been made in view of the above-mentioned problems, and a corner segment that does not lower the yield strength even when an abdominal pressure acts on the corner of the covering body, and a covering body including the segment. The purpose is to provide.

The present invention is a substantially polygonal lining body constructed by assembling a plurality of reinforced concrete segments having inner main reinforcing bars and outer main reinforcing bars in a shield tunnel,
The inner peripheral surface of the corner is formed in a curved shape, and the corner is constructed so that the thickness is larger in the direction perpendicular to the axis of the covering body than the other part. To do.

  According to the present invention, since the corner is thicker in the direction perpendicular to the axis of the lining body than other parts, even if a bending moment acts on the corner and a crack due to abdominal pressure occurs, the progress of the crack Can be suppressed. Therefore, the segment is not easily damaged, and the proof stress of the lining body is improved.

  Moreover, in this invention, it is good also as being arrange | positioned so that the edge part vicinity of the said inner side main reinforcement arrange | positioned at the adjacent edge | side of the said substantially polygonal shape may mutually cross | intersect at the said corner part.

  According to the present invention, since the vicinity of the end portions of the inner main reinforcing bars are arranged so as to intersect each other at the corners, the force at the intersecting portion of the inner main reinforcing bars is substantially a straight portion as shown in FIG. Along with the tensile forces T1 and T2 from, reverse tensile forces T1 ′ and T2 ′ having the same magnitude as those of T1 and T2 act. Since these four forces are balanced, the tensile resistance of the concrete is not large, and even if cracks C are generated, it is possible to suppress a great progress. As a result, the behavior of the inner main reinforcing bar shown by the phantom line in FIG.

  This invention is good also as providing the belt reinforcement provided so that the said inner main reinforcement and the said outer main reinforcement might be enclosed in the said corner.

  According to the present invention, the inner main reinforcing bars are less likely to move toward the inner side of the shield tunnel, and thus the behavior of the inner main reinforcing bars protruding to the inner side of the tunnel can be more reliably suppressed even when an abdominal pressure is applied.

The present invention is a concrete corner segment arranged in the corner of a substantially polygonal lining body installed in a shield tunnel,
An inner main reinforcing bar and an outer main reinforcing bar are provided, the inner peripheral surface is formed in a curved shape, and the corner is thicker in the direction perpendicular to the axis of the covering body than the other part. It is formed.

  According to the present invention, since the corner is thicker in the direction perpendicular to the axis of the lining body than other parts, even if a bending moment acts on the corner and a crack due to abdominal pressure occurs, the progress of the crack Can be suppressed. Therefore, the segment is not easily damaged, and the proof stress of the lining body is improved.

  ADVANTAGE OF THE INVENTION According to this invention, the segment for corners which does not fall a yield strength even if abdominal pressure acts on the corner of a covering body, and a covering body provided with the segment can be provided.

It is sectional drawing which shows the lining body installed in the tunnel excavated by the shield construction method. It is a figure which expands the A section of FIG. 1, and shows the segment for corners. It is a figure which shows the other example of fixation of an inside main reinforcing bar. It is a figure which shows the other example of fixation of an inside main reinforcing bar. It is a figure which shows balance of force when the edge part vicinity of an inner side main reinforcing bar is made to cross | intersect in a corner. It is a figure which shows the other example of arrangement | positioning of an inside main reinforcing bar. It is a figure which shows the example when not using a belt reinforcement. It is a figure which shows the example when not using a belt reinforcement. It is a figure which shows the other Example of this invention. It is a figure which shows the load which acts on the corner part of the conventional lining body.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a lining body 2 installed in a tunnel 1 excavated by a shield method.
As shown in FIG. 1, the lining body 2 is constructed in a substantially rectangular shape (corresponding to a substantially polygonal shape) by assembling a plurality of reinforced concrete segments 3. The assembly of segment 3 is carried out in the tail part of the shield machine.

FIG. 2 is an enlarged view of a portion A in FIG. 1 to show a corner segment 3a.
As shown in FIG. 2, the substantially square-shaped corner segment 3 a disposed at each corner 2 a of the lining body 2 is composed of concrete 6, and a plurality of inner main reinforcing bars 4 are disposed therein. And an outer main reinforcing bar 5.

The inner main reinforcing bar 4 and the outer main reinforcing bar 5 are embedded at predetermined depth positions determined by design or the like from the inner peripheral surface and the outer peripheral surface, respectively.
Further, the inner main reinforcing bars 4 are respectively substantially horizontal to the top plate portion 2b (corresponding to a substantially straight portion) and the bottom plate portion 2c (corresponding to a substantially straight portion) of the lining body 2, and the left and right side portions 2d (substantially). (Corresponding to a straight line portion).

  The outer peripheral surface and the inner peripheral surface of the corner segment 3a have different radii of curvature R1 and R2, respectively. The curvature radius R1 of the outer peripheral surface is set to be smaller than the value (R2 + W) obtained by adding the thickness W of the end portion 3e of the corner segment 3a to the curvature radius R2 of the inner peripheral surface, whereby both end portions 3e, The outer peripheral surface is formed so as to gradually thicken outward from 3e toward the bent portion 3b.

  In the present embodiment, the outer peripheral surface has the curvature radius R1, but may be formed at a right angle (R1≈0). In short, in the corner segment 3a, the bent portion 3b may have a shape in which the thickness is larger in the direction perpendicular to the axis of the covering body 2 than the end portion 3e.

  The plurality of inner main reinforcing bars 4 are provided so that the vicinity of the end portions thereof intersect with each other at the corners 2 a, the tips thereof are folded back, and the folded portions are close to the outer main reinforcing bar 5. Has been placed. Thereby, the inner main reinforcement 4 can be fixed to the concrete 6. Therefore, even if the tensile forces T1 and T2 in the tensile direction act on the inner main reinforcing bar 4, the inner main reinforcing bar 4 is fixed to the concrete 6, so that cracks in the corner 2a caused by the tensile forces T1 and T2 are prevented. Progress can be suppressed.

  In addition, in this embodiment, although the case where the edge part of the inner side main reinforcement 4 was turned back was demonstrated, it is not limited to this, As shown in FIG. A fixing portion 8 or the like may be attached to provide a widened portion. In short, the compression region of the concrete 6 that is compressed by a load of a preset size acting from the ground to the inside of the tunnel 1 due to an earthquake or the like ( In the present embodiment, it is only necessary that the end portion of the inner main reinforcing bar 4 reaches within the dotted line in the drawing and the inner main reinforcing bar 4 is sufficiently fixed to the concrete 6 with respect to the tensile forces T1 and T2. .

  Moreover, in this embodiment, although the case where the folding | returning part of the inner main reinforcement 4 was arrange | positioned so that it might adjoin to the outer main reinforcement 5 was demonstrated, it is not limited to this, The location where the inner main reinforcement 4 crossed If a fixing length sufficient to maintain fixing with respect to the tensile forces T1 and T2 can be secured from 4a to the tip, for example, as shown in FIG. 4, the tip of the inner main reinforcing bar 4 is not folded back and the tip is the outer peripheral portion of the segment 3. It may be arranged up to the vicinity.

  In the corner 2a, a belt reinforcing bar 7 is provided so as to surround the inner main reinforcing bar 4 and the outer main reinforcing bar 5. A plurality of band reinforcing bars 7 are provided at and around the location 4a where the vicinity of the ends of the inner main reinforcing bars 4 intersect. In addition, although not shown in figure, you may provide the belt reinforcement 7 in the top plate part 2b or the bottom plate part 2c.

  According to the lining body 2 described above, since the bent portion 3b of the corner segment 3a is configured to be thicker than other portions, the bending moment M acts on the corner portion 2a to generate the abdominal pressure T. Even if the corner segment 3a is cracked, the progress can be suppressed. Therefore, the corner segment 3a is not easily damaged, and the proof stress of the lining body 2 is improved.

  Further, even if tensile forces T1 and T2 are applied to the inner main reinforcing bar 4 due to the bending moment M, the fixing length from the point 4a where the end portions of the inner main reinforcing bar 4 intersect each other to the tip is sufficiently secured. The inner main reinforcing bar 4 does not protrude into the tunnel 1. Therefore, it is possible to suppress the progress of cracks in the corner 2a caused by the tensile forces T1 and T2.

  Further, as shown in FIG. 5, the force at the location 4a where the vicinity of the end portions of the inner main reinforcing bar 4 intersects is the same tensile force T1 'as that of T1 and T2, and the opposite tensile force T1'. , T2 ′ acts. Since these four forces are balanced, the tensile resistance of the concrete 6 is not large, and even if a crack is generated, it can be prevented from greatly progressing. As a result, the behavior of the inner main reinforcing bar 4 indicated by the phantom line in FIG.

  In addition, in this embodiment, although the case where the some inner main reinforcing bar 4 was made to cross | intersect was demonstrated, it is not limited to this, As shown in FIG. May be arranged, and the inner main reinforcing bar 4 and the outer main reinforcing bar 5 of the bent portion 3 b may be connected by the band reinforcing bar 7.

By the way, since the curvature radius R1 of the outer peripheral surface is smaller than the value (R2 + W) obtained by adding the thickness W of the end 3e to the curvature radius R2 of the inner peripheral surface, as shown in FIGS. Since the covering thickness L from the outer peripheral side end to the outer peripheral surface of the band reinforcing bar 7 arranged in the vicinity of the bent portion 3b is larger than the covering thickness S from the outer main reinforcing bar 5 to the outer peripheral surface of the end portion 3e, durability is maintained. it can.
Further, since the effective height from the intersecting portion 4a of the inner main reinforcing bar 4 to the outer peripheral surface is longer than the effective height from the inner main reinforcing bar 4 to the outer peripheral surface of the end portion 3e, the bending strength can be ensured.

  In the present embodiment, the case where the inner main reinforcing bar 4 and the outer main reinforcing bar 5 are connected by the belt reinforcing bar 7 has been described. However, the present invention is not limited to this, and as shown in FIGS. The band rebar 7 may not be used.

  In addition, in this embodiment, although the case where the lining body 2 was constructed in a substantially rectangular shape was described, it is not limited to this shape, and may be a substantially polygonal shape, as shown in FIG. For example, it may be a pentagon, and is determined by appropriate design according to each site situation such as soil quality and depth.

DESCRIPTION OF SYMBOLS 1 Tunnel 2 Covering body 2a Corner | angular part 2b Top plate part 2c Bottom plate part 2d Side part 3 Segment 3a Corner segment 3b Bending part 3e End part 4 Inner main reinforcement 4a Intersection 5 Outer main reinforcement 6 Concrete 7 Band reinforcement 8 Mechanical fixing device 12 Corner 13 Segment

Claims (4)

A substantially polygonal lining body constructed by assembling a plurality of reinforced concrete segments having an inner main reinforcing bar and an outer main reinforcing bar in a shield tunnel,
The inner peripheral surface of the corner is formed in a curved shape, and the corner is constructed so that the thickness is larger in the direction perpendicular to the axis of the covering body than the other part. Lining body to be.   The lining body according to claim 1, wherein the vicinity of the end portions of the inner main reinforcing bars arranged on adjacent sides of the substantially polygonal shape are arranged so as to intersect each other at the corners. .   The lining body according to claim 1, further comprising a belt reinforcing bar provided so as to surround the inner main reinforcing bar and the outer main reinforcing bar at the corner. A concrete corner segment placed in a corner of a substantially polygonal lining body installed in a shield tunnel,
An inner main reinforcing bar and an outer main reinforcing bar are provided, the inner peripheral surface is formed in a curved shape, and the corner is thicker in the direction perpendicular to the axis of the covering body than the other part. A corner segment formed by being formed.

Images