Spacer for securing the thickness of shear reinforcement steel bars, and shear reinforcement method for existing concrete structures

Abstract

To provide a spacer which is suitable for securing a covering thickness of a shear reinforcing bar used in a shear reinforcement method.SOLUTION: A spacer has a first surface, a second surface positioned opposite to the first surface in a depth direction of a drilled hole part where the spacer is embedded, a side face for connecting the first surface and the second surface in the depth direction of the drilled hole part, and a grove part formed in substantially a depth direction on the side face positioned in a first region with a largest outer diameter at least when viewed in a depth direction in the side face. The side face of the spacer positioned at least in the first region extends to a direction substantially parallel to the depth direction of the drilled hole part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a spacer for ensuring a predetermined cover thickness for a shear reinforcement bar inserted into a drilled hole when implementing a shear reinforcement method, and also to a method for shear reinforcement of an existing concrete structure using the spacer. [Background technology]

[0002] Conventionally, a shear reinforcement method has been known as a method for seismic reinforcement of existing concrete structures. The shear reinforcement method is a method for increasing shear stress by forming holes in the surface of an existing structure and embedding steel materials inside the holes (see, for example, Patent Document 1 and Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-181473 A [Patent Document 2] JP 2015-218465 A Summary of the Invention [Problem to be solved by the invention]

[0004] When implementing the shear reinforcement method, reinforcing bars are often inserted as reinforcing steel into holes drilled into existing concrete structures. However, if the reinforcing bars are exposed to the outside air, they will rust and corrode. For this reason, the entire reinforcing bars are positioned completely within the drilled holes so that the ends of the reinforcing bars are not exposed, and then a specified filler (repair material) is filled in.

[0005] When performing shear reinforcement on an existing structure for seismic reinforcement, several hundred or more reinforcing bars may be inserted into the structure depending on the size of the existing structure. Therefore, in order to properly insert reinforcing bars in all locations, it is preferable to ensure the covering thickness of the reinforcing bars in a simple manner.

[0006] From this viewpoint, the present inventors have newly considered the use of spacers to ensure the cover thickness of the shear reinforcement steel bars when performing the shear reinforcement method. As a result of this consideration, the inventors have come up with a new problem when using spacers to perform the shear reinforcement method, which is different from the problem of using spacers to ensure the cover thickness of the steel bars when constructing a new concrete structure. More specifically, the inventors have newly found that, depending on the shape and structure of the spacer, the position of the spacer may fluctuate during the hardening process of the repair material, and in some cases, the end of the spacer may protrude from the wall surface of the structure, or the spacer may not be sufficiently adhered to the repair material.

[0007] In view of the above problems, the present invention aims to provide a spacer that is particularly suitable for securing the cover thickness of shear reinforcing bars used in shear reinforcement construction methods. The present invention also aims to apply a shear reinforcement method for existing concrete structures using such a spacer. [Means for solving the problem]

[0008] The present invention is a spacer for ensuring the cover thickness of a shear reinforcement bar, The first page and a second surface located on the opposite side to the first surface in a depth direction of the bored hole in which the spacer is embedded; A side surface connecting the first surface and the second surface in the depth direction of the hole-making portion; a groove formed substantially along the depth direction on at least the side surface located in a first region having the largest outer diameter as viewed in the depth direction, The side surface located at least in the first region is characterized in that it extends in a direction substantially parallel to the depth direction of the hole-drilling portion.

[0009] By making the side surface of the largest outer diameter portion of the spacer (first region) substantially parallel to the depth direction of the drilled hole, the embedded spacer is less likely to move within the drilled hole during the hardening process of the repair material. Here, "substantially parallel" may mean that the angle between the depth direction of the drilled hole and the extension direction of the side surface of the first region of the spacer is within ±10°, more preferably within ±7°, and particularly preferably within ±5°.

[0010] Furthermore, according to the above-mentioned spacer, a groove is formed along the depth direction on the side surface in the first region, which has the largest outer diameter. Therefore, even if the outer diameter of the spacer in the first region is extremely close to the inner diameter of the drilled hole, the repair material can penetrate in the depth direction along this groove, and the adhesion between the repair material and the spacer is improved. Furthermore, by providing this groove, the repair material trapped in the groove improves the adhesion between the spacer and the drilled hole.

[0011] When viewed in the depth direction, the outer diameter of the first region is preferably 0.7 to 0.98 times the inner diameter of the hole-drilled portion.

[0012] By embedding a spacer formed with such dimensions within the drilled hole, the phenomenon in which the position of the spacer moves within the drilled hole during the hardening process of the repair material becomes even less likely to occur.

[0013] When viewed in the depth direction, the first region of the spacer has protruding portions protruding toward the inner wall surface of the hole-drilling portion at three or more locations spaced apart in the circumferential direction, The groove may be formed in at least the protruding portion.

[0014] According to the above-mentioned configuration, the inner surface of the drilled hole portion and the outer circumferential surface of the spacer can be brought into close proximity at at least three points, which enhances the effect of stabilizing the position of the spacer within the drilled hole portion even during the hardening process of the repair material.

[0015] the spacer has a tapered portion in a second region adjacent to the first region in the depth direction, the tapered portion having an outer diameter gradually decreasing depending on a position in the depth direction, the first region is a region including the first surface, The outer diameter of the first region may be substantially uniform depending on the position in the depth direction.

[0016] According to the above configuration, the spacer has a tapered portion, which facilitates the work of inserting the spacer into the drilled hole. In addition, the first region of the spacer, which has a large outer diameter, is located adjacent to the region (second region) in the depth direction where the tapered portion is formed, and this first region is substantially uniform depending on the position in the depth direction. In other words, the region where the outer surface of the spacer and the inner surface of the drilled hole are closest to each other is ensured to be at least a certain distance in the depth direction. As a result, the effect of stabilizing the position of the spacer in the drilled hole is enhanced even during the hardening process of the repair material.

[0017] In the above, the outer diameter of the first region being substantially uniform depending on the position in the depth direction means that a slight variation of about less than 5% of the outer diameter is allowed.

[0018] When the spacer has a tapered portion, the direction of the taper, i.e., the direction in which the outer diameter gradually decreases, may be toward the wall side (front side) of the concrete structure, or toward the interior side (rear side) of the concrete structure.

[0019] In other words, in the first embodiment, the surface (the first surface) belonging to the first region, which is adjacent to the second region where the tapered portion is formed, may be the surface that comes into contact with the shear reinforcement directly or via a jig. In this case, the taper direction, i.e., the direction in which the outer diameter gradually decreases, is toward the wall side (near side) of the concrete structure.

[0020] In a second embodiment, the surface (the second surface) belonging to the second region where the tapered portion is formed may be a surface that comes into contact with the shear reinforcement directly or via a jig. In this case, the taper direction, i.e., the direction in which the outer diameter gradually decreases, is toward the inside (rear side) of the existing concrete structure.

[0021] In the first embodiment, it is preferable to fill the cut hole with the repair material after embedding the spacer in the cut hole, so that the repair material can easily penetrate into the existing concrete structure in the depth direction through the space between the side surface of the tapered portion and the cut hole.

[0022] On the other hand, in the case of the second embodiment, it is preferable to fill the cut hole with the repair material and then embed the spacer. By embedding the spacer, the repair material already filled is pushed out through the space between the side of the tapered portion and the cut hole, and it becomes easier for the repair material to penetrate into the wall side (near side) of the existing concrete structure in the depth direction.

[0023] The spacer may have an IC tag built therein that is capable of communicating with a reader or a reader / writer.

[0024] After the repair material is filled, the shear reinforcement is completely embedded in the concrete structure, and its inside cannot be seen. However, by using a spacer for ensuring the cover thickness of shear reinforcement with an IC tag built in as described above, it is possible to easily confirm that the appropriate cover thickness has been ensured for the shear reinforcement by bringing a reader or reader / writer close to the concrete structure after the shear reinforcement work has been carried out and reading the IC tag, which can be used for management purposes.

[0025] The method for shear reinforcement of an existing concrete structure according to the present invention comprises the steps of: A step (a) of preparing a spacer for ensuring the cover thickness of the shear reinforcement bar described above; A process (b) of cutting the existing concrete structure in the depth direction to form a drilled hole; A step (c) of filling an area including the inner bottom of the drilled hole with an anchoring material; (d) inserting a shear reinforcement bar in the depth direction from the opening surface toward the inner bottom so that the shear reinforcement bar is completely accommodated on the inner bottom side from the opening surface of the drilled hole in the depth direction; After the steps (b) to (d) are performed, a step (e) of positioning the spacer for ensuring the cover thickness of the shear reinforcement prepared in the step (a) in the region between the shear reinforcement and the opening surface in the drilled hole; The method is characterized by having a step (f) of filling a repair material into the area between the shear reinforcement bar in the drilled hole and the opening surface, after steps (b) to (d) and before or after step (e).

[0026] According to the above method, the spacer can be stably held at a desired position within the drilled hole while ensuring an appropriate cover thickness for the shear reinforcement bar. Effect of the Invention

[0027] According to the present invention, an appropriate cover thickness for shear reinforcement bars can be ensured in a simple manner. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a conceptual diagram showing a procedure for performing shear reinforcement on an existing concrete structure. [Diagram 2] FIG. 1 is a conceptual diagram showing a procedure for performing shear reinforcement on an existing concrete structure. [Figure 3A] 1 is a diagram showing a schematic view of a shear reinforcement bar with an anchoring jig attached thereto, together with a spacer. [Figure 3B]1 is a schematic diagram showing a shear reinforcement bar without an anchoring jig attached thereto, together with a spacer. [Figure 4] 1 is a drawing for explaining the cover thickness of shear reinforcement bars. [Diagram 5] 1 is a diagram illustrating a schematic diagram of a communication state between an IC tag embedded in a spacer and a reader / writer. [Figure 6A] 1 is a diagram showing a schematic diagram of an example of a method for manufacturing a spacer having an IC tag built in. [Figure 6B] 1 is a diagram showing a schematic diagram of an example of a method for manufacturing a spacer having an IC tag built in. [Figure 7A] FIG. 2 is a perspective view showing a shape of a first embodiment of a spacer. [Figure 7B] FIG. 2 is a plan view illustrating a shape of a spacer according to a first embodiment of the present invention; [Figure 8A] 5A and 5B are cross-sectional views each showing a schematic example of a shape of a groove portion formed in a spacer. [Figure 8B] 11A and 11B are cross-sectional views each showing a schematic example of a groove portion formed in a spacer having another shape. [Figure 8C] 10A and 10B are cross-sectional views each showing a schematic example of a shape of a groove portion formed in a spacer. [Figure 9] 11 is a diagram for explaining the relationship between the outer diameter of a spacer and the inner diameter of a drilled hole portion. [Figure 10] FIG. 11 is a plan view illustrating a shape of a spacer according to a second embodiment of the present invention; [Figure 11A] FIG. 13 is a perspective view showing a shape of a spacer according to a third embodiment of the present invention; [Figure 11B] FIG. 11 is a plan view illustrating a shape of a spacer according to a third embodiment of the present invention; [Figure 12] FIG. 13 is a plan view illustrating a shape of a fourth embodiment of a spacer. [Figure 13A] 13 is a diagram for explaining the orientation of a spacer embedded in a drilled hole. [Figure 13B] 13 is another diagram for explaining the orientation of the spacer embedded in the drilled hole. [Figure 14A]FIG. 2 is a schematic top view of a concrete specimen in which the spacers of Examples 1 and 2 are embedded. [Figure 14B] FIG. 2 is a schematic top view of a concrete specimen in which the spacer of Reference Example 1 is embedded. [Figure 15A] FIG. 2 is a schematic cross-sectional view of a concrete specimen in which the spacers of Examples 1 and 2 are embedded. [Figure 15B] 3 is a schematic cross-sectional view of a concrete specimen in which the spacer of Reference Example 1 is embedded. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, embodiments of the spacer for ensuring the cover thickness of shear reinforcement bars and the method for shear reinforcement of an existing concrete structure according to the present invention will be described with reference to the drawings. However, the drawings are schematic illustrations, and the actual dimensional ratios do not necessarily match the dimensional ratios in the drawings, and the dimensional ratios do not necessarily match between the drawings.

[0030] 1 and 2 are conceptual diagrams that show a procedure for providing shear reinforcement to an existing concrete structure. As shown in Fig. 1 and Fig. 2, in the following description, the extension direction of a shear reinforcement steel bar 5 inserted into an existing concrete structure 1 (hereinafter abbreviated as "existing structure 1") is defined as the X direction, and the height direction (typically the vertical direction) of the existing structure 1 is defined as the Y direction.

[0031] In the following description, when a positive or negative direction is to be distinguished when expressing a direction, the direction is described with a positive or negative sign, such as "+X direction" and "-X direction". When a direction is to be expressed without distinguishing between positive and negative directions, the direction is simply described as "X direction". In other words, in this specification, when the direction is simply described as "X direction", both the "+X direction" and the "-X direction" are included.

[0032] [Shear reinforcement method] First, an embodiment of a shear reinforcement method according to the present invention will be described with reference to the drawings. Then, an embodiment of a spacer for ensuring the cover thickness of a shear reinforcement bar according to the present invention will be described with reference to the drawings.

[0033] (Step S1) When carrying out the shear reinforcement method according to the present invention, a spacer 10 for ensuring the covering thickness of the shear reinforcement steel bars (hereinafter, simply abbreviated as "spacer 10") is used, which will be described later with reference to Figures 6A to 12. For this reason, the spacer 10 is prepared in advance before carrying out work on an existing structure 1 (see Figure 1) that is to be subjected to shear reinforcement.

[0034] As will be described later with reference to FIG. 5, the spacer 10 of this embodiment incorporates an IC tag 30 capable of communicating with a reader or reader / writer (hereinafter collectively referred to as a "reader / writer 40").

[0035] This step S1 corresponds to the process (a).

[0036] (Step S2) When performing shear reinforcement on an existing structure 1, first, as shown in Fig. 1, a bottomed hole 3 is formed in the existing structure 1 from the wall surface 1a side toward the depth direction (X direction). A drilling device such as a core drill or a high-pressure water injection device such as a water jet can be used to form the hole 3.

[0037] The hole drilling section 3 is provided for the purpose of subsequently burying the shear reinforcement bars 5. For this reason, it is necessary to form the hole drilling section 3 at a location that avoids the main reinforcements and distribution bars provided in the existing structure 1. Therefore, before forming the hole drilling section 3, it is preferable to determine in advance the installation locations of the main reinforcements and distribution bars by using a rebar detection device that uses electromagnetic waves, such as an RC radar.

[0038] When forming the hole drilling portion 3, a widening process may be performed to widen the inner diameter of the hole drilling portion 3 at a position close to the wall surface 1a, i.e., at a position close to the opening surface. After the hole drilling portion 3 is formed, pressurized air may be sent into the hole drilling portion 3 using an air compressor or the like as necessary to remove foreign matter such as drilling chips from the hole drilling portion 3.

[0039] This step S2 corresponds to the process (b).

[0040] (Step S3) Next, as shown in FIG. 2, an anchoring material (grout material) 7 is injected into the drilled hole 3 in an amount that will not overflow out of the opening of the drilled hole 3 even when the shear reinforcement steel bar 5 is inserted later as a shear reinforcement member. This process fills the anchoring material 7 in a predetermined area including the inner bottom 3a of the drilled hole 3. As the anchoring material 7, mortar, cement milk (a mixture of cement and water), or resin can be suitably used, and among these, mortar is particularly preferable. In the subsequent step S4, in order to insert the shear reinforcement steel bar 5 into the drilled hole 3 with the anchoring material 7 injected inside, the anchoring material 7 is made of a material that has high fluidity before hardening and hardens over time.

[0041] This step S3 corresponds to the step (c).

[0042] (Step S4) Next, as shown in Fig. 2, the shear reinforcement bar 5 is inserted in the +X direction into the drilled hole 3. The shear reinforcement bar 5 enters the drilled hole 3 in the +X direction while pushing aside the anchorage material 7 injected in step S3.

[0043] In the example of Fig. 2, a structure in which fixing jigs (5a, 5b) are attached to both ends of the shear reinforcement 5 in the longitudinal direction is shown, but as described later with reference to Figs. 3A to 3B, the presence or absence of these jigs (5a, 5b) is optional. The shear reinforcement 5 is inserted to a position where the end on the -X side (jig 5a if jig 5a is attached) is completely housed in the drilled hole 3. More specifically, in the next step S5, the shear reinforcement 5 is inserted in the depth direction (+X direction) to a position where a space can be secured for completely embedding the spacer 10 at a position adjacent to the -X side of the shear reinforcement 5.

[0044] This step S4 corresponds to step (d).

[0045] (Step S5) 2, a spacer 10 is inserted into the hole-drilling portion 3. This spacer 10 is the one prepared in step S1 described above.

[0046] The spacer 10 is inserted until it abuts against the end of the -X side of the shear reinforcement bar 5 (the jig 5a if the jig 5a is attached). The spacer 10 is inserted so that the end of the -X side is not exposed on the wall surface 1a side of the existing structure 1.

[0047] As shown in FIG. 3A, when jigs (5a, 5b) are attached to the shear reinforcement 5, the end face (first surface 11) on the +X side of the spacer 10 is abutted against the jig 5a. Figure 3B As shown in FIG. 1, when no jig (5a, 5b) is attached to the shear reinforcement bar 5, the +X side end face (first surface 11) of the spacer 10 abuts against the -X side end face of the shear reinforcement bar 5.

[0048] 9, the spacer 10 has a shape in which the maximum outer diameter in a plane direction perpendicular to the depth direction (X direction) has a certain ratio to the inner diameter in the same direction of the hole-making portion 3. Preferably, the maximum outer diameter of the spacer 10 is 0.7 to 0.98 times, and more preferably 0.8 to 0.98 times, the inner diameter of the hole-making portion 3. In other words, when the spacer 10 is inserted into the hole-making portion 3, the point where the outer diameter of the spacer 10 is greatest is in close proximity to the inner wall of the hole-making portion 3.

[0049] This step S5 corresponds to step (e).

[0050] (Step S6) Next, as shown in FIG. 2, the remaining space in the drilled portion 3 is filled with repair material 8, and the opening surface of the drilled portion 3 is connected to the wall surface 1a of the existing structure 1, thereby closing the opening surface. The repair material 8 may be the same material as the fixing material 7, or may be a different material. However, unlike the fixing material 7, the repair material 8 is injected for the purpose of ensuring continuity with the wall surface 1a of the existing structure 1, and therefore a part of it is exposed to the outside. From this point of view, it is preferable that the material is a material that exhibits stable properties even when exposed to the air. Mortar or cement milk is preferably used.

[0051] In particular, when the repair material 8 is made of the same material as the fixing material 7, the repair material 8 and the fixing material 7 may be regarded as being integrated in FIG.

[0052] This step S6 corresponds to the process (f).

[0053] The order of step S5 of embedding the spacer 10 and step S6 of injecting the repair material 8 may be reversed. That is, the repair material 8 may be injected first, and then the spacer 10 may be embedded in the hole drilling section 3. In this case, by intruding the spacer 10 in the depth direction (X direction), a part of the repair material 8 is pushed out and moves toward the wall surface 1a side of the existing structure 1 (i.e., the opening surface side of the hole drilling section 3) through the space between the spacer 10 and the hole drilling section 3. As a result, the repair material 8 covers the opening surface of the hole drilling section 3, thereby repairing it. Note that a part of the repair material 8 attached to the wall surface 1a of the existing structure 1 located outside the hole drilling section 3 may be appropriately removed depending on the amount of exposure.

[0054] Through the above steps S1 to S6, the shear reinforcement bars 5 are inserted into the existing structure 1 in a direction (here, the X direction) different from the vertical direction (the Y direction), thereby increasing the shear strength of the existing structure 1 and improving its earthquake resistance.

[0055] In addition, since the spacers 10 are embedded in step S5, the covering thickness of the shear reinforcement bars 5 is reliably secured at least for the length of the spacers 10 in the X direction. During work, it is sufficient to insert the shear reinforcement bars 5 for the length required for embedding the spacers 10 in step S5, and then embed the spacers 10 in the subsequent step S6. Therefore, no complicated work is required.

[0056] The cover thickness of the shear reinforcement bar 5 is the distance L5 between the end of the shear reinforcement bar 5 on the side (-X side) close to the wall surface 1a of the existing structure 1 after construction and the wall surface 1a of the existing structure 1 (see FIG. 4). As shown in FIG. 4, when a jig (5a, 5b) is attached to the end of the shear reinforcement bar 5, the distance L5 between the end face on the -X side of this jig and the wall surface 1a of the existing structure 1 may be taken as the cover thickness of the shear reinforcement bar 5. When a jig (5a, 5b) is not attached to the end of the shear reinforcement bar 5, the distance L5 between the end face on the -X side of the shear reinforcement bar 5 itself and the wall surface 1a of the existing structure 1 may be taken as the cover thickness of the shear reinforcement bar 5.

[0057] (Step S7) Furthermore, as in this embodiment, by equipping the spacer 10 with an IC tag 30, it is possible to easily confirm from the outside of the wall surface 1a of the existing structure 1 that the shear reinforcement bars 5 are buried with an appropriate cover thickness ensured.

[0058] That is, as shown in Fig. 5, after the work of steps S1 to S6 is completed, the reader / writer 40 is brought close to the wall surface 1a of the existing structure 1. When the shear reinforcement bars 5 are buried in the existing structure 1 through the procedure of steps S1 to S6, communication W1 becomes possible with the IC tag 30 embedded in the spacer 10. As a result, the information written on the IC tag 30 is read by the reader / writer 40, and it can be confirmed that the shear reinforcement bars 5 are buried with an appropriate cover thickness ensured.

[0059] From this viewpoint, the IC tag 30 may be previously recorded with information on the cover thickness, the specifications of the shear reinforcement bars 5, the buried position, the date of work, etc. The information recorded on the IC tag 30 may include information other than the above-mentioned examples as long as it is information that can be used for management, or may include part of the above-mentioned information.

[0060] It should be noted that this step S7 may be carried out for confirmation immediately after the completion of the shear reinforcement work relating to steps S1 to S6 above, or may be carried out for the purpose of inspection, etc., a predetermined number of days after the completion of the above work.

[0061] [Spacer for securing cover thickness of shear reinforcement bars] Next, the structure of the spacer 10 used in the above-mentioned shear reinforcement method will be described with reference to the drawings.

[0062] 6A and 6B are diagrams that diagrammatically show an example of a method for manufacturing the spacer 10 in the case where the spacer 10 has an IC tag 30 built therein.

[0063] The body of the spacer 10 is made of mortar, ceramics, plastic, or the like, and is preferably made of mortar or ceramics. When the body of the spacer 10 is made of mortar, high-strength mortar is preferably used. When the body of the spacer 10 is made of ceramics, Al2O3 or ZrO2 is preferably used.

[0064] The spacer 10 may have a shape such as a columnar body, a shape in which a columnar body and a frustum are combined, etc. The detailed shape of the spacer 10 will be described later.

[0065] When manufacturing the spacer 10, for example, a method of bonding two partial spacers (10A, 10B) as shown in Fig. 6A can be used. A hole 31 for embedding an IC tag 30 is provided on one surface 10a of one partial spacer 10A, and the IC tag 30 is placed in this hole 31. Thereafter, the surface 10b of the other partial spacer 10B and the surface 10a of the partial spacer 10A are bonded together, for example, via mortar. As a result, a spacer 10 with an embedded IC tag 30 is obtained as shown in Fig. 6B.

[0066] Any known IC tag can be used as the IC tag 30, as long as it can be powered and written to and read from the memory at the same time using a reader / writer 40 (see FIG. 5). The frequency band of radio waves transmitted and received by the IC tag 30 can be a typical range of several hundred kHz to 3 GHz.

[0067] The IC tag 30 incorporates an antenna (not shown), and receives radio waves from the reader / writer 40 by means of this antenna. As described above with reference to FIG. 5, the IC tag 30 incorporated in the spacer 10 receives radio waves from the reader / writer 40 located outside the wall surface 1a of the existing structure 1. Therefore, from the viewpoint of ensuring the radio wave sensitivity required for reception, the embedding depth d30 of the IC tag 30 from the side closer to the wall surface 1a of the existing structure 1, that is, from the second surface 12 in FIG. 6B, is restricted within a certain range. Preferably, assuming that the length of the spacer 10 in the direction parallel to the depth direction (i.e., the X direction) of the drilling hole 3 is d10, the embedding depth d30 of the IC tag 30 is preferably set such that d30 < 0.6 × d10. Also, when d30 < 0.2 × d10, there is a risk that the strength of the spacer 10 itself will be reduced. Therefore, the embedding depth d30 of the IC tag 30 is preferably set such that 0.2 × d10 < d30 < 0.6 × d10.

[0068] Also, from the viewpoint of enhancing the reception sensitivity, the reception surface of the IC tag 30 is preferably installed so as to be substantially parallel to the opening surface of the drilling hole 3 (see FIG. 1). More specifically, it is preferable that the spacer 10 in a state where the IC tag 30 is incorporated on a plane substantially parallel to the first surface 11 or the second surface 12 is inserted into the drilling hole 3 along the direction orthogonal to the first surface 11 or the second surface 12.

[0069] [First Embodiment] FIGS. 7A to 7B are drawings schematically showing the shape of the first embodiment of the spacer 10, where FIG. 7A is a perspective view and FIG. 7B corresponds to a plan view. Note that FIG. 7B shows combined plan views of the spacer 10 as seen from two different directions. In FIG. 7B, (a) is a plan view of the spacer 10 as seen from the same direction as the drawing shown in FIG. 2, corresponding to a side view. Also, in FIG. 7B, (b) is a plan view of the spacer 10 as seen from the depth direction of the drilling hole 3, that is, the X direction, corresponding to a top view.

[0070] 7A to 7B has a substantially cylindrical shape. That is, the outer diameter is substantially the same regardless of the position in the X direction. Therefore, when the spacer 10 is viewed in the depth direction (X direction) of the hole-drilling portion 3, the region with the largest outer diameter (referred to as the "first region 21") corresponds to the entire area of ​​the spacer 10 in the X direction.

[0071] In the spacer 10, grooves 14 extending along the X direction are provided in the first region 21 on the side surface 13 of the spacer 10. As described above, in the case of the spacer 10 shown in Figures 7A and 7B, the first region 21 corresponds to the entire area of ​​the spacer 10 in the X direction, so the grooves 14 are provided over the entire area in the X direction. However, a plurality of grooves 14 are formed at positions spaced apart in the circumferential direction of the spacer 10 (see Figure 7B).

[0072] The shape of the groove 14 is arbitrary. For example, the bottom surface and inner side surface of the groove 14 may be curved as a whole as shown in Fig. 8A, some side surfaces may be flat as shown in Fig. 8B, or the bottom surface and inner side surface of the groove 14 may be flat as a whole as shown in Fig. 8C. The width of the groove 14 is also arbitrary, but a typical example is about 1 mm to 3 mm. The same applies to the second embodiment and the following embodiments described later.

[0073] 9 is a diagram for explaining the relationship between the inner diameter of the drilled portion 3 and the outer diameter of the spacer 10, and corresponds to a drawing of the spacer 10 when embedded in the drilled portion 3 as viewed in the depth direction (X direction). However, for convenience of explanation, the fixing material 7 and repair material 8 are omitted from FIG. 9.

[0074] The outer diameter D21 of the first region 21 of the spacer 10 is preferably 0.7 to 0.98 times, and more preferably 0.8 to 0.98 times, the inner diameter D3 of the hole-drilling portion 3. In other words, the portion of the spacer 10 where the outer diameter is greatest is almost close to the inner surface of the hole-drilling portion 3, while leaving some space therebetween. Thus, a portion of the repair material 8 can move in the X direction through this space.

[0075] 7B(b), in the first region 21 of the spacer 10, a groove 14 extending in the X direction is formed on the side surface 13. Therefore, a part of the repair material 8 can easily enter and move in the X direction through the groove 14. And, since the repair material 8 is also retained in the groove 14, the spacer 10 and the inner wall of the hole-drilled portion 3 are stably fixed to each other via the repair material 8.

[0076] [Second embodiment] Fig. 10 illustrates the spacer 10 of the second embodiment, following Fig. 7B. The spacer 10 of this embodiment has projections 15 that project radially from a plurality of positions spaced apart in the circumferential direction on the side surface 13. In this case, the outer diameter D21 of the spacer 10 at the positions where the projections 15 are formed is preferably 0.7 to 0.98 times the inner diameter D3 of the hole-drilled portion 3. The projections 15 are preferably provided at three or more positions spaced apart in the circumferential direction.

[0077] In the case of the shape shown in FIG. 10, a groove 14 extending in the X direction is formed on the side surface 13 of the spacer 10 at the location where the protrusion 15 is formed.

[0078] In the case of the shape shown in FIG. 10, a space is secured between the side surface 13 of the spacer 10 and the inner wall of the hole-making section 3 in the area where the protrusion 15 is not formed. Therefore, a part of the repair material 8 can move in the X direction through this space. As shown in FIG. 10(b), a groove 14 extending in the X direction is formed on the side surface 13 of the protrusion 15 corresponding to the position where the side surface 13 of the spacer 10 and the inner wall of the hole-making section 3 are closest to each other. Therefore, a part of the repair material 8 can easily enter and move in the X direction through the groove 14. And, since the repair material 8 is also retained in the groove 14, the spacer 10 and the inner wall of the hole-making section 3 are stably fixed to each other through the repair material 8.

[0079] [Third embodiment] 11A and 11B are drawings that diagrammatically show the shape of a third embodiment of the spacer 10, and are illustrated following Fig. 7A and Fig. 7B. That is, Fig. 11A corresponds to a perspective view of the spacer 10, and Fig. 11B corresponds to a plan view of the spacer 10. Note that Fig. 11B also shows plan views of the spacer 10 as viewed from two different directions, and the illustration method is the same as Fig. 7B.

[0080] 11A and 11B has a first region 21 having a substantially cylindrical shape and a second region 22 adjacent to the first region 21 and having a gradually decreasing outer diameter. That is, the side surface 13 of the spacer 10 has a columnar side surface portion 13a having a substantially uniform outer diameter regardless of the position in the X direction, and a tapered portion 13b having an outer diameter that gradually decreases depending on the position in the X direction.

[0081] In the case of the spacer 10 of this embodiment, the first region 21 having the columnar side portion 13a is the region with the largest outer diameter in the depth direction (X direction), and the second region 22 having the tapered portion 13b has an outer diameter smaller than that of the first region 21. The minimum outer diameter of the tapered portion 13b is arbitrary, but from the viewpoint of maintaining the strength of the spacer 10, it is preferable that it is 50% or more of the maximum outer diameter (the outer diameter of the columnar side portion 13a). In the example shown in FIG. 11A, the IC tag 30 is embedded in the second region 22 of the spacer 10, but it is also possible to embed the IC tag in the first region 21 of the spacer 10 by appropriately setting the lengths in the X direction of the first region 21 and the second region 22.

[0082] In the spacer 10 of this embodiment, in the first region 21, a groove portion 14 extending along the X direction is provided on the side surface 13 of the spacer 10. On the other hand, in the second region 22 of the spacer 10, no groove portion 14 is formed on the side surface 13. However, this embodiment does not exclude a configuration in which the groove portion 14 is formed on the side surface 13 in the second region 22.

[0083] In the case of the spacer 10 of this embodiment, the outer diameter in the second region 22 is smaller than that in the first region 21. Therefore, in the second region 22, a space is secured between the side surface 13 of the spacer 10 and the inner wall of the hole-drilled portion 3. Therefore, a part of the repair material 8 can move in the X direction through this space.

[0084] Meanwhile, in the first region 21, which is a region where the outer diameter of the spacer 10 is large, a groove 14 extending in the X direction is formed on the side surface 13, i.e., on the columnar side surface portion 13a. Therefore, a part of the repair material 8 can easily enter and move in the X direction through the groove 14. And, since the repair material 8 is also retained in the groove 14, the spacer 10 and the inner wall of the hole-drilled portion 3 are stably fixed to each other via the repair material 8.

[0085] 12(a), a certain distance is ensured in the X direction in the first region 21, which is a region where the outer diameter of the spacer 10 is large. Therefore, a certain area in the X direction is ensured where the outer side surface of the spacer 10 and the inner wall of the hole-making portion 3 are close to each other in the hole-making portion 3. Therefore, even if the side surface 13 has a shape with a tapered portion 13b like the spacer 10 of this embodiment, the degree of freedom of movement in the hole-making portion 3 is extremely low, similar to the spacer 10 of the first and second embodiments.

[0086] [Fourth embodiment] Fig. 12 illustrates a spacer 10 of a fourth embodiment, following Fig. 10. Like the spacer 10 of the third embodiment, the spacer 10 of this embodiment has a first region 21 having a substantially cylindrical shape and a second region 22 adjacent to the first region 21 and having a gradually decreasing outer diameter. Furthermore, like the spacer 10 of the second embodiment, the spacer 10 of this embodiment has protrusions 15 formed at a plurality of positions spaced apart in the circumferential direction. However, this differs from the second embodiment in that the protrusions 15 are not formed in the second region 22.

[0087] In the spacer 10 of this embodiment, similarly to the third embodiment, the outer diameter of the second region 22 is reduced compared to the first region 21. Therefore, in the second region 22, a space is secured between the side surface 13 of the spacer 10 and the inner wall of the hole-drilled portion 3. Thus, a part of the repair material 8 can move in the X direction through this space.

[0088] In the first region 21, in a portion where the protrusion 15 is not formed, a space is secured between the side surface 13 of the spacer 10 and the inner wall of the hole-drilling portion 3. Therefore, a part of the repair material 8 formed through this space can move in the X direction.

[0089] 12(b), in the first region 21, a groove 14 extending in the X direction is formed on the side surface 13 of the protruding portion 15 corresponding to the position where the side surface 13 of the spacer 10 and the inner side surface of the hole-drilling portion 3 are closest to each other. Therefore, a part of the repair material 8 can easily enter and move in the X direction through the groove 14. And, since the repair material 8 is also retained in the groove 14, the spacer 10 and the inner wall of the hole-drilling portion 3 are stably fixed to each other via the repair material 8.

[0090] In addition, when the spacer 10 has a first region 21 having a substantially uniform outer diameter and a second region 22 having a gradually decreasing outer diameter, as in the case of the spacer 10 of the third and fourth embodiments, in step S5, the spacer 10 may be inserted so that the first region 21 is on the side of the shear reinforcement bar 5 (see Figure 13A), or conversely, the spacer 10 may be inserted so that the second region 22 is on the side of the shear reinforcement bar 5 (see Figure 13B).

[0091] However, when the spacer 10 is embedded in the orientation shown in Fig. 13A, it is preferable to execute step S6 of injecting the repair material 8 after executing step S5 of embedding the spacer 10. This makes it easier for the repair material 8 to penetrate toward the shear reinforcement bar 5 through the space between the side surface (tapered portion 13b) of the second region 22 of the spacer 10 and the inner wall of the drilled portion 3.

[0092] On the other hand, when the spacer 10 is embedded in the direction shown in FIG. 13B, it is preferable to execute step S5 of embedding the spacer 10 after executing step S6 of injecting the repair material 8. When the spacer 10 is embedded in the direction shown in FIG. 13B, the part where the inner wall of the hole drilling section 3 and the outer wall of the spacer 10 are closest to each other is the part close to the wall surface 1a of the existing structure 1. Therefore, if the repair material 8 is injected after the spacer 10 is embedded, the repair material 8 may not penetrate deep in the +X direction. On the other hand, by injecting the repair material 8 first and then inserting the spacer 10, a part of the repair material 8 pushed out by the spacer 10 is likely to proceed to the exposed surface side (-X direction) through the space between the tapered part 13b of the spacer 10 and the inner wall of the hole drilling section 3. This allows the repair material 8 to penetrate into the hole drilling section 3 at a position on the -X side of the spacer 10. EXAMPLES

[0093] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0094] Example 1 A spacer 10 of Example 1 was produced. This spacer 10 had the same shape as the spacer 10 of the above-mentioned first embodiment, with an outer diameter of 3.5 cm and a length in the X direction of 5.0 cm. The IC tag 30 built into the spacer 10 was located at a depth of 2.5 cm from the first surface 11.

[0095] Example 2 The spacer 10 of Example 2 was produced under the same conditions as those of Example 1, except that the outer diameter was 4.9 cm.

[0096] (Reference example 1) A spacer 70 of Reference Example 1 was produced under the same conditions as those of Example 1, except that the outer diameter was 3.0 cm.

[0097] [Verification method] A column-shaped concrete specimen was prepared, with a rectangular shape of 10 cm square at the bottom and top, and a height of 40 cm, and a drilled hole 3 of 5 cm diameter and 20 cm depth was provided in the center of the top. A deformed reinforcing bar of 13 mm diameter and 15 cm length was inserted into the drilled hole 3 until one end of the bar abutted against the bottom of the drilled hole 3, and then mortar was filled in as an anchoring material 7 until the other end of the reinforcing bar was not hidden.

[0098] Next, the spacers (10, 10, 70) of Example 1, Example 2, and Reference Example 1 were abutted against the other end of the reinforcing bar, and the drilled hole 3 was filled with mortar as a repair material 8. Then, it was cured for 28 days.

[0099] After 28 days had passed, the following checking procedures were carried out on each of the concrete specimens in which the spacers (10, 10, 70) of Example 1, Example 2, and Reference Example 1 were embedded.

[0100] (Check 1) The condition of the surface of the construction part of the concrete specimen was observed. In the cases of Example 1 and Example 2, the spacer 10 was positioned with its outer surface at a substantially equal distance from the inner wall surface of the hole-drilling part 3 (see FIG. 14A). In contrast, in the case of Reference Example 1, the spacer 70 was fixed in a state in which it had moved in the Y direction within the hole-drilling part 3 (see FIG. 14B).

[0101] Furthermore, in the case of Reference Example 1, a part of the spacer 10 protruded in the -X direction from the wall surface 1a (corresponding to the upper surface) of the concrete specimen (see FIG. 15B). In contrast, in the cases of Examples 1 and 2, the spacer 10 was held in a state where it remained within the drilled hole portion 3 (see FIG. 15A).

[0102] (Check 2) The reader / writer 40 was brought close to each concrete specimen in which the spacers (10, 10, 70) of Example 1, Example 2, and Reference Example 1 were embedded, and communication was performed, as in Fig. 5. As a result, in each case, normal communication was performed with the IC tag 30 embedded in the spacer 10, and the information written on the IC tag 30 was read.

[0103] (Check 3) Each concrete specimen in which the spacers (10, 10, 70) of Example 1, Example 2, and Reference Example 1 were embedded was cut along a plane parallel to the XY plane, and the cut surface was observed. As a result, in the case of Reference Example 1, it was confirmed that the spacer 70 was fixed in an inclined state, as shown in FIG. 15B. In addition, some gaps were confirmed between the inner wall of the hole drilling section 3 and the outer surface of the spacer 70. In contrast, in the cases of Example 1 and Example 2, it was confirmed that the spacer 10 was fixed while maintaining a state that was almost parallel to the depth direction (X direction) of the hole drilling section 3, as shown in FIG. 15A.

[0104] From this result, in the case of Reference Example 1, in which a spacer 70 having an outer diameter as small as 0.6 times the inner diameter of the hole-drilling portion 3 was used, it is presumed that the spacer 70 moved within the hole-drilling portion 3 during the hardening process of the mortar. In contrast, in the cases of Example 1, in which a spacer 10 having an outer diameter as small as 0.7 times the inner diameter of the hole-drilling portion 3 was used, and Example 2, in which a spacer 10 having an outer diameter as small as 0.98 times the inner diameter of the hole-drilling portion 3 was used, it is presumed that the space between the outer wall of the spacer 10 and the inner wall of the hole-drilling portion 3 was relatively narrow, so that the spacer 70 was unlikely to move within the hole-drilling portion 3 even during the hardening process of the mortar, and was maintained in its pre-hardening state.

[0105] [Another embodiment] In the above embodiment, the spacer 10 has a built-in IC tag 30. However, the present invention does not exclude the case where the spacer 10 does not have a built-in IC tag 30. [Explanation of symbols]

[0106] 1: Existing concrete structure 1a: Wall 3: Drilling section 3a: Inner bottom 5: Shear reinforcement bars 5a, 5b: Jig 7: Fixing agent 8: Repair materials 10: Spacer for ensuring the thickness of the shear reinforcement bars 10A, 10B: Partial spacer 11: Front page 12:Second side 13: Side 13a: Columnar side part 13b: Tapered section 14: Groove 15:Protrusion 21:First area 22:Second area 30: IC tag 31: Hole 40: Reader / writer 70: Example spacer

Claims

1. A spacer for ensuring the thickness of a shear reinforcement bar, The first page and a second surface located on the opposite side to the first surface in a depth direction of the bored hole in which the spacer is embedded; A side surface connecting the first surface and the second surface in the depth direction of the hole-making portion; a groove portion formed along the depth direction on at least the side surface located in a first region having the largest outer diameter as viewed in the depth direction, A spacer for ensuring the cover thickness of shear reinforcement bars, characterized in that at least the side surface located in the first region extends in a direction substantially parallel to the depth direction of the drilled hole portion.

2. The spacer for ensuring the cover thickness of shear reinforcement bars as described in claim 1, characterized in that, when viewed in the depth direction, the outer diameter of the first region is 0.7 to 0.98 times the inner diameter of the drilled portion.

3. When viewed in the depth direction, the first region has protruding portions protruding toward the inner wall surface of the hole-making portion at three or more locations spaced apart in the circumferential direction, 3. The spacer for ensuring the covering thickness of a shear reinforcement bar according to claim 1, wherein the groove portion is formed at least in the protruding portion.

4. a second region adjacent to the first region in the depth direction has a tapered portion whose outer diameter gradually decreases depending on a position in the depth direction; the first region is a region including the first surface, The spacer for ensuring the cover thickness of shear reinforcement bars according to any one of claims 1 to 3, characterized in that the outer diameter of the first region is substantially uniform depending on the position in the depth direction.

5. The spacer for ensuring the covering depth of a shear reinforcement bar according to claim 4, characterized in that the first surface is a surface that comes into contact with the shear reinforcement bar directly or via a jig.

6. The spacer for ensuring the covering depth of a shear reinforcement bar according to claim 4, characterized in that the second surface is a surface that comes into contact with the shear reinforcement bar directly or via a jig.

7. 7. The spacer for ensuring the covering depth of shear reinforcement bars according to claim 1, further comprising an IC tag built therein that is capable of communicating with a reader or a reader / writer.

8. A step (a) of preparing a spacer for ensuring the cover thickness of a shear reinforcement bar according to any one of claims 1 to 7; A step (b) of cutting an existing concrete structure in a depth direction to form a drilled hole; A step (c) of filling an area including an inner bottom of the drilled hole with an anchoring material; A process (d) of inserting a shear reinforcement bar from the opening surface toward the inner bottom in the depth direction so that the shear reinforcement bar is completely accommodated on the inner bottom side from the opening surface of the drilled hole in the depth direction; After carrying out the steps (b) to (d), a step (e) of positioning the spacer for ensuring the cover thickness of the shear reinforcement prepared in the step (a) in the region between the shear reinforcement and the opening surface in the drilled hole; A method for shear reinforcement of an existing concrete structure, comprising a step (f) of filling a repair material into an area between the shear reinforcement bar in the drilled hole and the opening surface, after steps (b) to (d) and before or after step (e).

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