JP7654513B2 - Spacer for securing the thickness of shear reinforcement steel bars, and shear reinforcement method for existing concrete structures - Google Patents

Description

The present invention relates to a spacer that ensures a predetermined cover thickness for the shear reinforcement bar that is inserted into a drilled hole when implementing the shear reinforcement method. The present invention also relates to a shear reinforcement method for an existing concrete structure that uses this spacer.

Conventionally, the 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 material inside the holes (see, for example, Patent Document 1 and Patent Document 2).

JP 2014-181473 A JP 2015-218465 A

When carrying out shear reinforcement methods, 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 bar is positioned completely within the drilled hole so that the ends of the reinforcing bars are not exposed, and then a specified filler (repair material) is filled in.

When carrying out shear reinforcement work 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. For this reason, in order to properly insert reinforcing bars in all locations, it is preferable to be able to ensure the covering thickness of the reinforcing bars in a simple manner.

From this perspective, the inventors have newly considered the use of spacers to ensure the cover thickness of the shear reinforcing bars when carrying out the shear reinforcement method. As a result of this consideration, they have come up with the idea that when using spacers to carry out the shear reinforcement method, there are new issues that differ from when using spacers to ensure the cover thickness of the reinforcing bars when constructing a new concrete structure. More specifically, they have newly discovered 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 ends of the spacer may protrude from the wall surface of the structure, or the spacer may not adhere sufficiently to the repair material.

In view of the above problems, the present invention aims to provide a spacer that is particularly suitable for ensuring the cover thickness of shear reinforcement 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.

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.

By making the side of the largest outer diameter part 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 of the first region of the spacer is within ±10°, more preferably within ±7°, and particularly preferably within ±5°.

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, improving the adhesion between the repair material and the spacer. Furthermore, by providing this groove, the repair material trapped in the groove improves the adhesion between the spacer and the drilled hole.

When viewed in the depth direction, it is preferable that the outer diameter of the first region is 0.7 to 0.98 times the inner diameter of the drilled portion.

By embedding a spacer formed to these dimensions within the drilled hole, it becomes even less likely that the position of the spacer will move within the drilled hole as the repair material hardens.

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

The above configuration allows the inner surface of the drilled hole section and the outer peripheral surface of the spacer to be brought into close proximity at at least three locations. This enhances the effect of stabilizing the position of the spacer within the drilled hole section even during the hardening process of the repair material.

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.

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 in the depth direction to the region (second region) 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 within the drilled hole is enhanced even during the hardening process of the repair material.

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 less than 5% of the outer diameter is permitted.

If 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.

In other words, in the first embodiment, the surface (the first surface) belonging to the first region, which is adjacent to the second region in which 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 direction of the taper, i.e., the direction in which the outer diameter decreases, is toward the wall side (near side) of the concrete structure.

In a second embodiment, the surface belonging to the second region in which the tapered portion is formed (the second surface) 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 decreases, is toward the inside (rear) of the existing concrete structure.

In the first embodiment, it is preferable to fill the cut hole with repair material after embedding the spacer in the cut hole. This makes it easier for the repair material to penetrate into the existing concrete structure in the depth direction through the space between the side of the tapered portion and the cut hole.

On the other hand, in the case of the second embodiment, it is preferable to fill the cut hole with 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, making it easier for the repair material to penetrate in the depth direction toward the wall side (near side) of the existing concrete structure.

The spacer may have an IC tag built in that can communicate with a reader or reader/writer.

After the repair material has been filled, the shear reinforcement bars are completely embedded within the concrete structure, making it impossible to see inside. However, as described above, by using a spacer for ensuring the cover thickness of shear reinforcement bars with an embedded IC tag, it is possible to easily confirm that the appropriate cover thickness has been ensured for the shear reinforcement bars 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.

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 step (b) of cutting the 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) is performed in which the spacer for ensuring the cover thickness of the shear reinforcement prepared in the step (a) is positioned in the region between the shear reinforcement and the opening surface in the drilled hole portion;
The method is characterized in that it includes 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 carrying out the steps (b) to (d) and before or after carrying out the step (e).

The above method allows the spacer to be stably held in the desired position within the drilled hole while ensuring an appropriate cover thickness for the shear reinforcement bars.

The present invention provides a simple method for ensuring an appropriate cover thickness for shear reinforcement bars.

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

Embodiments of the spacer for ensuring the cover thickness of shear reinforcement bars and the method for shear reinforcement of existing concrete structures according to the present invention will be described below 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.

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

In the following description, when a positive or negative direction needs to be distinguished, the direction is described with a positive or negative sign, such as "+X direction" and "-X direction". When a direction is described 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.

[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.

(Step S1)
When carrying out the shear reinforcement method according to the present invention, a spacer 10 for ensuring the cover 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 the existing structure 1 (see Figure 1) that is to be subjected to shear reinforcement.

As will be described later with reference to FIG. 5, the spacer 10 of this embodiment has an IC tag 30 built in that can communicate with a reader or reader/writer (hereinafter collectively referred to as a "reader/writer 40").

This step S1 corresponds to process (a).

(Step S2)
When performing shear reinforcement on an existing structure 1, first, as shown in Fig. 1, a bottomed drilled 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 drilled hole 3.

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 in a location that avoids the main reinforcement bars and distribution bars installed 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 reinforcement bars and distribution bars, for example, by using a rebar detection device that uses electromagnetic waves such as an RC radar.

When forming the hole drilling section 3, a widening process may be performed to widen the inner diameter of the hole drilling section 3 at a position close to the wall surface 1a, i.e., at a location close to the opening surface. After the hole drilling section 3 is formed, if necessary, high-pressure air may be sent into the hole drilling section 3 using an air compressor or the like to remove foreign matter such as drilling waste from the hole drilling section 3.

This step S2 corresponds to process (b).

(Step S3)
Next, as shown in FIG. 2, an amount of fixing material (grout material) 7 is injected into the drilled hole 3 so that it does 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 fixing material 7 in a predetermined area including the inner bottom 3a of the drilled hole 3. As the fixing material 7, mortar, cement milk (a mixture of cement and water), or resin can be suitably used, and among these, mortar is particularly preferred. In the subsequent step S4, in order to insert the shear reinforcement steel bar 5 into the drilled hole 3 with the fixing material 7 injected inside, the fixing material 7 is made of a material that has high fluidity before hardening and hardens over time.

This step S3 corresponds to process (c).

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

In the example of FIG. 2, a structure is shown in which fixing jigs (5a, 5b) are attached to both longitudinal ends of the shear reinforcement 5, but as described later with reference to FIG. 3A-FIG. 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 contained within 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 space can be secured to completely embed the spacer 10 adjacent to the -X side of the shear reinforcement 5.

This step S4 corresponds to process (d).

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

The spacer 10 is inserted until it abuts against the end of the -X side of the shear reinforcement bar 5 (or the jig 5a if one 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.

As shown in Fig. 3A, when the jigs (5a, 5b) are attached to the shear reinforcement 5, the end face (first surface 11) on the +X side of the spacer 10 abuts against the jig 5a. Also, as shown in Fig. 3B , when the jigs (5a, 5b) are not attached to the shear reinforcement 5, the end face (first surface 11) on the +X side of the spacer 10 abuts against the end of the shear reinforcement 5 on the -X side.

As will be described later with reference to FIG. 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-drilling section 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-drilling section 3. In other words, when the spacer 10 is inserted into the hole-drilling section 3, the point where the outer diameter of the spacer 10 is greatest is in close proximity to the inner wall of the hole-drilling section 3.

This step S5 corresponds to process (e).

(Step S6)
Next, as shown in FIG. 2, the remaining space in the drilled portion 3 is filled with a 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 different. 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 the repair material 8 is exposed to the outside. From this viewpoint, 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.

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 considered to be integrated in FIG. 2.

This step S6 corresponds to process (f).

The order of step S5 of embedding the spacer 10 and step S6 of injecting the repair material 8 may be reversed. In other words, the repair material 8 may be injected first, and then the spacer 10 may be embedded in the drilled hole portion 3. In this case, by inserting 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 drilled hole portion 3) through the space between the spacer 10 and the drilled hole portion 3. As a result, the repair material 8 covers the opening surface of the drilled hole portion 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 drilled hole portion 3 may be appropriately removed depending on the amount of exposure.

Through 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), increasing the shear resistance of the existing structure 1 and improving its earthquake resistance.

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

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) closer to the wall surface 1a of the existing structure 1 after construction and the wall surface 1a of the existing structure 1 (see Figure 4). As shown in Figure 4, if a jig (5a, 5b) is attached to the end of the shear reinforcement bar 5, the cover thickness of the shear reinforcement bar 5 may be the distance L5 between the end face on the -X side of this jig and the wall surface 1a of the existing structure 1. If a jig (5a, 5b) is not attached to the end of the shear reinforcement bar 5, the cover thickness of the shear reinforcement bar 5 may be 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.

(Step S7)
Furthermore, as in this embodiment, since the spacer 10 is equipped 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.

That is, as shown in FIG. 5, after steps S1 to S6 are 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 built into 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 the appropriate cover thickness ensured.

From this perspective, the IC tag 30 may be pre-recorded with information such as 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 examples as long as it is information that can be used for management, or may include part of the information listed in the above examples.

This step S7 may be performed for confirmation immediately after the completion of the shear reinforcement work related to steps S1 to S6 above, or may be performed for the purpose of inspection, etc., a specified number of days after the completion of the above work.

[Spacer for securing the covering 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.

Figures 6A and 6B are diagrams that show an example of a manufacturing method for a spacer 10 when the spacer 10 has an IC tag 30 built in.

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.

The shape of the spacer 10 can be a columnar body, a shape that combines a columnar body and a frustum, etc. The detailed shape of the spacer 10 will be described later.

When manufacturing the spacer 10, for example, a method of gluing two partial spacers (10A, 10B) together can be used, as shown in FIG. 6A. 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. Then, the surface 10b of the other partial spacer 10B and the surface 10a of the partial spacer 10A are glued together, for example, with mortar. This results in a spacer 10 with an embedded IC tag 30, as shown in FIG. 6B.

A publicly known IC tag 30 can be used, as long as it can be powered and can simultaneously write to and read from memory using a reader/writer 40 (see Figure 5). The frequency band of radio waves transmitted and received by the IC tag 30 can be in the general range of several hundred kHz to 3 GHz.

The IC tag 30 has a built-in antenna (not shown), which receives radio waves from the reader/writer 40. As described above with reference to FIG. 5, the IC tag 30 built into the spacer 10 receives radio waves from the reader/writer 40 located outside the wall surface 1a of the existing structure 1. For this reason, in order to ensure the radio wave sensitivity required for reception, the embedment depth d30 of the IC tag 30 from the side closer to the wall surface 1a of the existing structure 1, i.e., the second surface 12 in FIG. 6B, is limited to a certain range. Preferably, when the length of the spacer 10 in the direction parallel to the depth direction (i.e., the X direction) of the drilled hole portion 3 is d10, the embedment depth d30 of the IC tag 30 is set to d30<0.6×d10. In addition, when d30<0.2×d10, the strength of the spacer 10 itself may be reduced. Therefore, it is preferable that the embedding depth d30 of the IC tag 30 is set to 0.2 x d10 < d30 < 0.6 x d10.

In order to increase the reception sensitivity, it is preferable that the receiving surface of the IC tag 30 is installed so as to be substantially parallel to the opening surface of the hole-drilling section 3 (see FIG. 1). More specifically, it is preferable that the spacer 10 with the IC tag 30 embedded on a surface approximately parallel to the first surface 11 or the second surface 12 is inserted into the hole-drilling section 3 in a direction perpendicular to the first surface 11 or the second surface 12.

[First embodiment]
7A and 7B are drawings that show the shape of the first embodiment of the spacer 10, with 7A being a perspective view and 7B being a plan view. In addition, in 7B, plan views of the spacer 10 as viewed from two different directions are also shown. In 7B, (a) is a plan view of the spacer 10 as viewed from the same direction as the drawing shown in FIG. 2, and corresponds to a side view. In 7B, (b) is a plan view of the spacer 10 as viewed from the depth direction of the hole-drilling portion 3, i.e., the X direction, and corresponds to a top view.

The spacer 10 shown in Figures 7A and 7B has a substantially cylindrical shape. In other words, its 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.

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

The shape of the groove portion 14 is arbitrary. For example, the bottom surface and inner side surface of the groove portion 14 may be curved as a whole as shown in FIG. 8A, some of the sides may be flat as shown in FIG. 8B, or the bottom surface and inner side surface of the groove portion 14 may be flat as a whole as shown in FIG. 8C. The width of the groove portion 14 is also arbitrary, but a typical example is about 1 mm to 3 mm. The same applies to the second embodiment and subsequent embodiments described below.

Figure 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 state when the spacer 10 is 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 Figure 9.

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 section 3. In other words, the part of the spacer 10 with the largest outer diameter is almost close to the inner surface of the hole-drilling section 3, but some space is still secured. Therefore, part of the repair material 8 can move in the X direction through this space.

Furthermore, as shown in FIG. 7B(b), in the first region 21 of the spacer 10, a groove portion 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 portion 14. And, since the repair material 8 is also retained in this groove portion 14, the spacer 10 and the inner wall of the drilled portion 3 are stably fixed via the repair material 8.

[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 circumferentially spaced positions 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-drilling portion 3. The projections 15 are preferably provided at three or more positions spaced circumferentially.

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 where the protrusion 15 is formed.

In the case of the shape shown in FIG. 10, in the places 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 section 3. 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-drilling 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 this groove 14, the spacer 10 and the inner wall of the hole-drilling section 3 are stably fixed via the repair material 8.

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

The spacer 10 shown in Figures 11A and 11B has a first region 21 that is substantially cylindrical, and a second region 22 adjacent to the first region 21, in which the outer diameter gradually decreases. In other words, the side surface 13 of the spacer 10 has a columnar side surface portion 13a whose outer diameter is substantially uniform regardless of the position in the X direction, and a tapered portion 13b whose outer diameter gradually decreases depending on the position in the X direction.

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 (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 it 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.

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

In the case of the spacer 10 of this embodiment, the outer diameter is reduced in the second region 22 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 drilled portion 3. Therefore, a part of the repair material 8 can move in the X direction through this space.

On the other hand, in the first region 21, which is the 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 this groove 14, the spacer 10 and the inner wall of the drilled portion 3 are stably fixed via the repair material 8.

As shown in FIG. 12(a), the first region 21, which is the region with the larger outer diameter of the spacer 10, has a certain distance in the X direction. Therefore, the area in the hole-drilling section 3 where the outer surface of the spacer 10 is close to the inner wall of the hole-drilling section 3 is ensured over a certain area in the X direction. Therefore, even if the side surface 13 has a tapered portion 13b as in the spacer 10 of this embodiment, the degree of freedom of movement in the hole-drilling section 3 is extremely low, as in the spacer 10 of the first and second embodiments.

[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.

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

In the first region 21, 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 drilled hole portion 3. Therefore, a part of the repair material 8 can move in the X direction through this space.

Furthermore, as shown in FIG. 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 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 this groove 14, the spacer 10 and the inner wall of the hole-drilling portion 3 are stably fixed via the repair material 8.

In the case of the spacer 10 of the third and fourth embodiments, which has a first region 21 with a substantially uniform outer diameter and a second region 22 with a gradually decreasing outer diameter, in step S5, the spacer 10 may be inserted so that the first region 21 faces the shear reinforcement bar 5 (see FIG. 13A), or conversely, the spacer 10 may be inserted so that the second region 22 faces the shear reinforcement bar 5 (see FIG. 13B).

However, when embedding the spacer 10 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.

On the other hand, when the spacer 10 is embedded in the orientation 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 orientation shown in FIG. 13B, the closest point between the inner wall of the drilled hole portion 3 and the outer wall of the spacer 10 is the closest point to the wall surface 1a of the existing structure 1, so if the repair material 8 is injected after the spacer 10 is embedded, it may be difficult for the repair material 8 to penetrate deep in the +X direction. On the other hand, by first injecting the repair material 8 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 portion 13b of the spacer 10 and the inner wall of the drilled hole portion 3. This allows the repair material 8 to penetrate into the drilled hole portion 3 at a position on the -X side of the spacer 10.

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

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

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.

(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.

[Verification method]
A column-shaped concrete specimen was prepared, with a rectangular shape of 10 cm diameter on 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.

Next, the spacers (10, 10, 70) of Example 1, Example 2, and Reference Example 1 were attached to 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.

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

(Check 1)
The condition of the surface of the concrete specimen was observed. In the cases of Examples 1 and 2, the spacer 10 was positioned with its outer surface at a substantially equal distance from the inner wall surface of the hole-drilling section 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 section 3 (see FIG. 14B).

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).

(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.

(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 on 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 drilled hole portion 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 drilled hole portion 3 as shown in FIG. 15A.

From these results, in the case of Reference Example 1, in which a spacer 70 with an outer diameter 0.6 times the inner diameter of the hole-drilling section 3 was used, which is relatively small, it is presumed that the spacer 70 moved within the hole-drilling section 3 during the hardening process of the mortar. In contrast, in the case of Example 1, in which a spacer 10 with an outer diameter 0.7 times the inner diameter of the hole-drilling section 3 was used, and Example 2, in which a spacer 10 with an outer diameter 0.98 times the inner diameter of the hole-drilling section 3 was used, it is presumed that the spacer 70 was unlikely to move within the hole-drilling section 3 even during the hardening process of the mortar, and was maintained in its pre-hardening state, since the space between the outer wall of the spacer 10 and the inner wall of the hole-drilling section 3 was relatively narrow.

[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.

Reference Signs List 1: Existing concrete structure 1a: Wall surface 3: Drilled hole portion 3a: Inner bottom 5: Shear reinforcement steel bars 5a, 5b: Jig 7: Anchoring material 8: Repair material 10: Spacer for ensuring cover thickness of shear reinforcement steel bars 10A, 10B: Partial spacer 11: First surface 12: Second surface 13: Side surface 13a: Column-shaped side surface portion 13b: Tapered portion 14: Groove portion 15: Protrusion portion 21: First region 22: Second region 30: IC tag 31: Hole portion 40: Reader/writer 70: Spacer of reference example

Claims (8)

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 steel, 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. The spacer for ensuring the cover thickness of shear reinforcement bars according to claim 1, characterized in that the outer diameter of the first region is 0.7 to 0.98 times the inner diameter of the drilled hole when viewed in the depth direction. 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. 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. The spacer for ensuring the cover thickness 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. The spacer for ensuring the cover thickness of shear reinforcement bars described in claim 4, characterized in that the second surface is a surface that comes into contact with the shear reinforcement bars directly or via a jig. A spacer for ensuring the thickness of a shear reinforcement bar according to any one of claims 1 to 6, characterized in that it has an IC tag built in that can communicate with a reader or a reader/writer. 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 the 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) is performed in which the spacer for ensuring the cover thickness of the shear reinforcement prepared in the step (a) is positioned in the region between the shear reinforcement and the opening surface in the drilled hole portion;
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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