JP2017008618A - Repair method of concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restore engaging force between a shear reinforcement and an inner or outer reinforcement and prevent decline in durability of a concrete structure, when the shear reinforcement has deteriorated due to a deformation of a bent hook part.SOLUTION: A repair method is for a concrete wall 1 having a shear reinforcement 30 with a bent hook part 40 hooked on an inner reinforcement group 10, a folded-back hook part hooked on an outer reinforcement group, and an intermediate part 33 therebetween. The repair method includes the following steps: a correction step in which the bent hook part 40 exposed by peeling off of concrete and of which a bent angle to the intermediate part 33 has reduced due to deformation is bent back so as to further reduce the bent angle; a fitting step in which an anchorage device 50 is fitted on the bent hook part 40 that has been bent back; a cutting step in which an excess length part 30a of the shear reinforcement 30 protruding from the anchorage device 50 is removed; and a casting step in which covering concrete 60 is cast to cover at least the anchorage device 50.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for repairing a concrete structure containing a reinforcing bar.

  Many concrete structures are embedded with reinforcing bars. For example, the wall of a box culvert that is buried in the ground and constructs underground tunnels for railways, underground tunnels for automobiles, and other underground structures has inner and outer reinforcing bars facing each other, and these inner and outer reinforcing bars. In some cases, a shear reinforcement bar connecting the two is embedded. Moreover, the same or substantially the same reinforcing bar as the inner reinforcing bar, the outer reinforcing bar, and the shear reinforcing bar may be embedded in the wall portion of the concrete structure other than the box culvert. The inner reinforcing bar is disposed near the inner surface of the wall portion, and the outer reinforcing bar is disposed near the outer surface of the wall portion. In other words, the inner reinforcing bar is arranged on the inner side of the neutral axis of the wall portion, and the outer reinforcing bar is arranged on the outer side of the neutral axis of the wall portion.

  The inner reinforcing bar and the outer reinforcing bar are formed in a lattice shape by a plurality of main reinforcing bars extending vertically and a plurality of horizontal reinforcing bars extending horizontally. On the other hand, the shear reinforcement is arranged so as to straddle the intersection of the main reinforcement and the lateral reinforcement in the inner reinforcing bar and the intersection of the principal and the lateral reinforcement in the outer reinforcement. In other words, the shear reinforcement crosses the neutral axis of the side wall. One end side of the shear reinforcing bar extending across the neutral axis is engaged with the intersection of the inner reinforcing bars, and the other end side of the shear reinforcing bar is engaged with the intersection of the outer reinforcing bars.

  Specifically, one end side of the shear reinforcement bar is bent by approximately 90 degrees and hooked at the intersection of the inner reinforcing bar or the outer reinforcing bar, and the other end side of the shear reinforcement bar is bent by approximately 180 degrees and the outer reinforcing bar or the inner reinforcing bar is bent. It is caught at the intersection.

  The difference between the bending angles at both ends of the shear reinforcement as described above is mainly based on construction restrictions. That is, in order to increase the engagement force between the shear reinforcing bar, the inner reinforcing bar, and the outer reinforcing bar, it is desirable to bend both ends of the shear reinforcing bar approximately 180 degrees and at least more than 90 degrees.

  However, if both ends of the shear reinforcing bar are bent more than 90 degrees, it becomes very difficult to hook the end of the shear reinforcing bar on both the inner reinforcing bar intersection and the outer reinforcing bar intersection.

  Therefore, conventionally, one end side of the shear reinforcing bar is bent by approximately 180 degrees, while the other end side of the shear reinforcing bar is bent by approximately 90 degrees. When engaging the shear reinforcing bar with the inner reinforcing bar and the outer reinforcing bar, after hooking one end side of the shear reinforcing bar bent about 180 degrees to the intersection of the inner reinforcing bars, the shear reinforcing bar bent about 90 degrees Hook the other end of the bar to the intersection of the outer bar. Alternatively, after one end side of the shear reinforcing bar bent approximately 180 degrees is hooked on the intersection of the outer reinforcing bars, the other end side of the shear reinforcing bar bent approximately 90 degrees is hooked on the intersection of the inner reinforcing bars.

  In the following description, of the both ends of the shear reinforcement, the end portion having a relatively large bending angle is referred to as a “folding hook portion”, and the end portion having a relatively small bending angle is referred to as a “folding hook portion”. It may be distinguished.

Japanese Patent Laying-Open No. 2015-21290

  As described above, the folding hook portion is provided on one end side of the shear reinforcing bar, and the folding hook portion is provided on the other end side of the shear reinforcing bar. When a large force is applied to a concrete structure due to an earthquake or the like, a large force is also applied to the internal reinforcing bars. At this time, the folding hook portion with a small bending angle is more easily bent back than the folding hook portion with a large bending angle. When the bending hook part is bent back, that is, when the bending angle of the bending hook part is reduced, the engagement force with the inner reinforcing bar or the outer reinforcing bar is weakened, and the function as the reinforcing bar is lost or lowered.

  An object of the present invention is to recover the engagement force between the shear reinforcement bar and the inner reinforcing bar or the outer reinforcing bar weakened by the deformation of the bent hook part to prevent a decrease in the yield strength of the concrete structure.

  The method for repairing a concrete structure according to the present invention includes a first reinforcing bar group and a second reinforcing bar group that are opposed to each other, including a main reinforcing bar and a horizontal reinforcing bar that are assembled in a lattice shape, and a first reinforcing bar that is hung on the first reinforcing bar group. An end portion, a second end portion hung on the second reinforcing bar group, and an intermediate portion between the first end portion and the second end portion, the first reinforcing bar group and the second reinforcing bar group Is a method for repairing a concrete structure having a shear reinforcing bar disposed across the wall. This repair method is a correction process in which the first end portion or the second end portion, which is exposed by peeling off of the concrete and whose bending angle with respect to the intermediate portion is reduced by deformation, is bent back so that the bending angle is further reduced. A mounting step of attaching a fixing tool to the bent back first end portion or the second end portion, a cutting step of removing an extra length portion of the shear reinforcing bar protruding from the fixing tool, and at least the fixing And placing a covering concrete covering the tool.

  In one aspect of the present invention, in the correcting step, the first end portion or the root portion of the second end portion or the vicinity thereof is softened by heating to bend back the first end portion or the second end portion.

  In another aspect of the present invention, the fixing tool has a through-hole into which the bent first end or the second end is inserted, and the fixing tool and the fixing tool are inserted into the fixing tool. The shear reinforcement is fixed by welding.

  In another aspect of the present invention, the fixing tool has a through-hole into which the bent first end or the second end is inserted, and the fixing tool and the fixing tool are inserted into the fixing tool. The shear reinforcement is fixed by adhesion.

  In another aspect of the present invention, the fixing tool has a through-hole into which the bent first end or the second end is inserted, and the shear reinforcing bar inserted into the fixing tool has a through hole. A retaining portion is provided to fix the fixing tool and the shear reinforcing bar.

  In another aspect of the present invention, the inner peripheral surface of the through hole of the fixing tool is provided with a tapered portion that gradually decreases in diameter toward the outer peripheral surface of the shear reinforcement.

  In another aspect of the present invention, the fixing tool has a flange portion that engages with at least one of the main reinforcing bar and the lateral reinforcing bar adjacent to the shear reinforcing bar to which the fixing tool is attached.

  According to the present invention, the engagement force between the shear reinforcing bar and the inner reinforcing bar or the outer reinforcing bar weakened due to the deformation of the bent hook portion is recovered, and a decrease in the proof stress of the concrete structure is prevented.

It is a perspective view which shows typically the internal structure of the concrete wall which is an example of repair object. It is a figure which shows the more realistic positional relationship etc. of the reinforcing bar shown by FIG. 1, Comprising: (a) is AA sectional drawing, (b) is a front view, (c) is a side view. It is a perspective view which shows the bending hook part which deform | transformed and exposed. It is a figure which shows the repair process of the shear reinforcement which the bending hook part deform | transformed, Comprising: (a), (b) is explanatory drawing which shows a correction process, (c) is explanatory drawing which shows a mounting process and a cutting process, (d ) Is an explanatory view showing a placing process. It is an expansion perspective view of a fixing tool. It is an expanded sectional view of a fixing tool. It is an expansion perspective view which shows one of the modifications of a fixing tool. It is an expansion perspective view which shows another one of the modification of a fixing tool. It is an expanded sectional view showing an example of a retaining part.

  Hereinafter, an example of an embodiment of the present invention will be described. As shown in FIG. 1, the concrete structure in the present embodiment is a concrete wall 1 whose one surface is covered with a ground G, and forms a side wall of an underground tunnel 2. In the following description, one surface of the concrete wall 1 covered with the ground G is referred to as “outer surface 3”, and one surface opposite to the outer surface 3 is referred to as “inner surface 4”. That is, the illustrated inner surface 4 of the concrete wall 1 forms a part of the inner wall of the underground tunnel 2.

  As shown in FIG. 1, a first reinforcing bar group 10 is embedded near the inner surface of the concrete wall, and a second reinforcing bar group 20 is embedded near the outer surface. Therefore, in the following description, the first reinforcing bar group 10 may be referred to as “inner reinforcing bar group 10” and the second reinforcing bar group 20 may be referred to as “outer reinforcing bar group 20”.

  The inner reinforcing bar group 10 includes a plurality of main reinforcing bars 11 and lateral reinforcing bars 12 assembled in a lattice pattern. In other words, the inner reinforcing bar group 10 includes a main reinforcing bar 11 extending vertically and a lateral reinforcing bar 12 extending horizontally. Similarly, the outer reinforcing bar group 20 includes a plurality of main bars 21 and lateral reinforcing bars 22 assembled in a lattice shape. In other words, the outer reinforcing bar group 20 is composed of a main reinforcing bar 21 extending vertically and a horizontal reinforcing bar 22 extending horizontally.

  The inner reinforcing bar group 10 and the outer reinforcing bar group 20 are opposed to each other across the neutral axis X of the concrete wall 1, and a plurality of shear reinforcing bars 30 are provided between the inner reinforcing bar group 10 and the outer reinforcing bar group 20. Is over.

  In FIG. 1, the inner reinforcing bar group 10 (the main reinforcing bar 11 and the lateral reinforcing bar 12), the outer reinforcing bar group 20 (the main reinforcing bar 21 and the horizontal reinforcing bar 22), and the shear reinforcing bar 30 are schematically shown. Therefore, FIG. 2 shows the positional relationship and number of the inner reinforcing bar group 10, the outer reinforcing bar group 20, and the shear reinforcing bar 30 that are closer to reality.

  As shown in FIGS. 1 and 2, the shear reinforcing bar 30 includes a first end 31 that is hung on the inner reinforcing bar group 10, a second end 32 that is hung on the outer reinforcing bar group 20, and these first end parts. The intermediate part 33 between 31 and the 2nd end part 32 is provided, and it is arrange | positioned ranging over the inner side reinforcing bar group 10 and the outer side reinforcing bar group 20. FIG.

  As most clearly shown in FIGS. 2A and 2C, the first end portions 31 of some of the shear reinforcement bars 30 are bent approximately 90 degrees with respect to the intermediate portion 33, and the second end portions 32 is bent about 180 degrees with respect to the intermediate portion 33. Further, the first end portion 31 of the remaining shear reinforcing bar 30 is bent approximately 180 degrees with respect to the intermediate portion 33, and the second end portion 32 is bent approximately 90 degrees with respect to the intermediate portion 33.

  As described above, each shear reinforcing bar 30 includes an end portion bent about 90 degrees with respect to the intermediate portion 33 and an end portion bent about 180 degrees with respect to the intermediate portion 33. In other words, each shear reinforcing bar 30 includes an end portion having a relatively small bending angle with respect to the intermediate portion 33 and an end portion having a relatively large bending angle with respect to the intermediate portion 33. In the following description, regardless of whether it is the first end portion 31 or the second end portion 32, an end portion having a relatively small bending angle with respect to the intermediate portion 33 is referred to as a “folding hook portion 40”. An end portion having a relatively large bending angle with respect to the intermediate portion 33 may be referred to as a “folding hook portion 41”. In addition, such a name is only a name for convenience of explanation. For example, the folding hook part may be called “90 degree hook”, and the folding hook part may be called “180 degree hook”.

  As described above, the folding hook portion 40 is provided on one end side of each shear reinforcing bar 30, and the folding hook portion 41 is provided on the other end side. And about some shear reinforcement bars 30, the bending hook part 40 is hung on the inner side reinforcing bar group 10, and the folding hook part 41 is hung on the outer side reinforcing bar group 20. Further, with respect to the remaining shear reinforcement bars 30, the folding hook part 40 is hooked on the outer reinforcing bar group 20, and the folding hook part 41 is hooked on the inner reinforcing bar group 10. In the following description, when the folding hook portion 40 and the folding hook portion 41 are not particularly distinguished, they may be collectively referred to as “hook portions”.

  When a large force is exerted on the concrete wall 1 having the above structure due to an earthquake or the like, a large force is also exerted on the concrete and the reinforcing bars inside thereof. As a result, as shown in FIG. 3, a part of the concrete (such as covered concrete) may be peeled off, and the hook portion of the shear reinforcing bar 30 may be deformed and exposed to the outside. At this time, the folding hook part 40 whose bending angle with respect to the intermediate part 33 is smaller than that of the folding hook part 41 is particularly easily deformed. Specifically, the bending hook part 40 is deformed so that the bending angle with respect to the intermediate part 33 decreases. Such a deformed state is sometimes referred to as “the hook opens” or “the hook opens”.

  When the bending hook portion 40 of the shear reinforcing bar 30 is deformed as described above, that is, when the hook of the shear reinforcing bar 30 is opened, the engagement force between the shear reinforcing bar 30 and the inner reinforcing bar group 10 or the outer reinforcing bar group 20 is reduced. The function as a reinforcing bar of the shear reinforcing bar 30 is lost or deteriorated.

  Next, the repair process of the shear reinforcement 30 in which the bending hook part 40 deform | transformed as mentioned above is demonstrated.

  As shown in FIG. 4A, the base portion of the deformed bending hook portion 40 or the vicinity thereof (the portion surrounded by a dotted line in the drawing) is softened by heating, and the bending angle with respect to the intermediate portion 33 is further reduced. Bend back (correction process). That is, as shown in FIG. 4B, the bent hook portion 40 is returned straight or substantially straight. For example, when the bending angle with respect to the intermediate portion 33 of the bending hook portion 40 that was initially 90 degrees is reduced to around 45 degrees due to the deformation, the bending angle is further reduced to 0 degrees or substantially 0 degrees. For the heating, for example, a gas burner is used.

  Next, as shown in FIG. 4C, the fixing device 50 is attached to the bent hook portion 40 that has been bent back (a mounting process). As shown in FIG. 5, the fixing tool 50 used in the present embodiment includes a cylindrical portion 51, a flange portion 52 provided at one end of the cylindrical portion 51, and a through hole 53 that penetrates the cylindrical portion 51 and the flange portion 52. And hardware with. As shown in FIG. 4C, in the mounting step, the bent hook portion 40 bent back is inserted into the through hole 53 (FIG. 5) of the fixing device 50. Further, the flange portion 52 of the fixing tool 50 engages with the lateral reinforcing bar 12 adjacent to the shear reinforcing bar 30 to which the fixing tool 50 is attached. That is, the fixing tool 50 is engaged with the lateral reinforcing bar 12 instead of the bending hook part 40, and the engagement force between the shear reinforcing bar 30 and the inner reinforcing bar group 10 is recovered.

  Thereafter, the fixing device 50 and the shear reinforcement 30 inserted in the through hole 53 (FIG. 5) of the fixing device 50 are fixed. In this embodiment, the fixing tool 50 and the shear reinforcing bar 30 inserted into the through hole 53 of the fixing tool 50 are fixed by welding. For this reason, as shown in FIG. 6, a tapered portion 53 a that gradually decreases in diameter toward the outer peripheral surface of the shear reinforcing bar 30 is provided on the inner peripheral surface of the through hole 53. The tapered portion 53 a is provided on the flange portion side of the through hole 53, and the diameter thereof gradually decreases as the distance from the flange portion 52 increases. The taper portion 53a functions as a liquid pool during welding, facilitates welding work, and ensures reliable and strong welding between the fixing tool 50 and the shear reinforcing bar 30.

  Next, as shown in FIG. 4C, the excess length portion 30a of the shear reinforcing bar 30 protruding from the fixing tool 50 is removed (cutting step).

  Next, as shown in FIG. 4D, the covering concrete 60 covering the reinforcing bars 50 and the reinforcing bars exposed by the concrete peeling is placed (placement step).

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the flange portion 52 of the fixing device 50 shown in FIGS. 4C and 4D may be engaged with both the lateral reinforcing bar 12 and the main bar 11, or may be engaged only with the main bar 11. Good. That is, the flange portion 52 may be engaged with at least one of the main reinforcing bar 11 and the lateral reinforcing bar 12 adjacent to the shear reinforcing bar 30 to which the fixing tool 50 is attached. The shape of the flange portion 52 may be changed so that the flange portion 52 is reliably and easily engaged with the main reinforcing bar 11 or the lateral reinforcing bar 12. For example, as shown in FIG. 7, the shape of the flange portion 52 may be changed to a circle concentric with the through hole 53. Further, as shown in FIG. 8, the shape of the flange portion 52 may be changed to a circular shape that is eccentric with respect to the through hole 53. Furthermore, the fixing tool 50 and the shear reinforcing bar 30 may be fixed by adhesion. Even when the fixing device 50 and the shear reinforcing bar 30 are fixed by bonding, the taper portion 53a of the fixing device 50 functions as a liquid pool in which an adhesive is accumulated, facilitating the bonding work, and shearing between the fixing device 50 and the shearing reinforcing bar 30. Secure and firm welding with the reinforcing bar 30 is ensured.

  Further, as shown in FIG. 9, the fixing tool 50 and the shear reinforcing bar 30 may be fixed by providing a retaining portion 61 at the end of the shear reinforcing bar 30 that penetrates the fixing tool 50.

  The concrete structure that can be repaired by the repairing method of the present invention is not limited to a concrete wall. The repair method of the present invention is, for example, by repairing a wall portion (side wall) of a box culvert buried in the ground, by placing concrete in a groove excavated in the ground, or by arranging precast members. It can also be applied to repairing the wall (side wall) of the constructed digging road. Moreover, the repair method of this invention is applicable also to repair of the wall part (vertical wall) of the retaining wall standing up from a bottom part (floor slab).

1 concrete wall 2 underground tunnel 3 outer surface 4 inner surface 10 1st reinforcing bar group (inner reinforcing bar group)
20 Second rebar group (outer rebar group)
11, 21 Main bars 12, 22 Lateral reinforcing bars 30 Shear reinforcing bars 30a Extra length portion 31 First end portion 32 Second end portion 33 Intermediate portion 40 Bending hook portion 41 Folding hook portion 50 Fixing tool 51 Tube portion 52 Flange portion 53 Through Hole 53a Tapered part 60 Covered concrete 61 Retaining part G Ground X Neutral shaft

Claims (7)

A first reinforcing bar group and a second reinforcing bar group that include a main reinforcing bar and a horizontal reinforcing bar that are assembled in a lattice shape, and that face each other;
A first end hung on the first reinforcing bar group, a second end hung on the second reinforcing bar group, and an intermediate portion between the first end and the second end, A method for repairing a concrete structure having a shear reinforcing bar disposed across a first reinforcing bar group and the second reinforcing bar group,
A correction step of bending back the first end portion or the second end portion, which is exposed by peeling off of the concrete and whose bending angle with respect to the intermediate portion is reduced by deformation, so that the bending angle is further reduced;
A mounting step of attaching a fixing tool to the bent back first end or the second end;
A cutting step of removing an extra length portion of the shear reinforcing bar protruding from the fixing tool;
And placing a covering concrete covering at least the fixing tool,
Repair method for concrete structures. In the repair method of the concrete structure of Claim 1,
In the correction step, the first end portion or the second end portion is softened by heating or the vicinity thereof, and the first end portion or the second end portion is bent back.
Repair method for concrete structures. In the repair method of the concrete structure of Claim 1 or 2,
The fixing device has a through hole into which the bent first end or the second end is inserted,
Fixing the fixing tool and the shear reinforcement inserted in the fixing tool by welding;
Repair method for concrete structures. In the repair method of the concrete structure of Claim 1 or 2,
The fixing device has a through hole into which the bent first end or the second end is inserted,
Fixing the fixing tool and the shear reinforcement inserted in the fixing tool by bonding;
Repair method for concrete structures. In the repair method of the concrete structure of Claim 1 or 2,
The fixing device has a through hole into which the bent first end or the second end is inserted,
Providing a retaining portion to the shear reinforcement inserted in the fixing tool to fix the fixing tool and the shear reinforcement;
Repair method for concrete structures. In the repair method of the concrete structure in any one of Claims 3-5,
A taper portion that gradually decreases in diameter toward the outer peripheral surface of the shear reinforcement bar is provided on the inner peripheral surface of the through hole of the fixing tool.
Repair method for concrete structures. In the repair method of the concrete structure in any one of Claims 1-6,
The fixing tool has a flange portion that engages with at least one of the main reinforcing bar and the lateral reinforcing bar adjacent to the shear reinforcing bar to which the fixing tool is attached.
Repair method for concrete structures.

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