JP7208840B2 - Method for shear reinforcement of reinforced concrete walls - Google Patents

Description

The present invention relates to a shear reinforcement method for reinforcing an existing reinforced concrete wall with a shear reinforcement member in post-construction.

Due to the deterioration of structures and the review of building standards, shear reinforcement is being carried out by fixing shear reinforcement members such as shear reinforcement bars to existing structures in order to improve seismic strength.

Shear reinforcement of existing reinforced concrete walls, for example, side walls of underground box culverts, is generally performed in the following procedure.

(1) In a reinforced concrete wall, a bottomed hole for inserting a shear reinforcing member is drilled in the horizontal direction from the inner wall surface toward the outer wall surface.
(2) A filling material (grout material) for fixing the shear reinforcing member is injected into the drilled hole to fill the hole.
(3) A shear reinforcing member such as a shear reinforcing reinforcing bar is inserted into the hole into which the filler has been injected, and the filler is fixed by solidification.

Further, Patent Document 1 relates to such a method for shear reinforcement of a reinforced concrete wall, in which a hole for inserting a shear reinforcement member is formed in the horizontal direction, so that the filled filler leaks from the entrance. In order to prevent this, it is proposed to install a storage tank for the filler on the inlet side of the hole prior to the injection and filling of the filler.

JP 2012-241332 A

However, in the conventional general method, the filling material needs to be highly viscous so as not to leak out because it is injected and filled into the horizontally drilled hole. Therefore, injection is not so easy.

Also, if the filler is not filled from the tip of the hole without gaps (without air pockets), fixability will deteriorate, so the injection hose must be inserted all the way to fill from the back. In this case, there is no choice but to use a thin injection hose due to the diameter of the drilled hole, and since the inner diameter of the hose is small, it takes time to inject the filler together with the high viscosity of the filler. It should be noted that increasing the drilling diameter increases the drilling cost and time, and increases the amount of filler material, resulting in an increase in cost.

In addition, in order to ensure the filling over the entire length, the filling material should overflow as the shear reinforcing member is inserted. For this reason, a storage tank or the like as described in Patent Document 1 is installed on the inlet side of the hole. Therefore, more filler than necessary is used, leading to an increase in cost. In addition, even if it is not discarded, but is recovered and used for the next drilling, workability deteriorates.

In view of such circumstances, the present invention is a method for shear reinforcement of reinforced concrete walls, which makes it possible to use a low-viscosity filler to facilitate injection and to suppress the use of an excessive amount of filler. The task is to provide

A method for shear reinforcement of a reinforced concrete wall according to the present invention comprises:
A drilling step of drilling a bottomed hole for inserting a shear reinforcing member in an existing reinforced concrete wall at a downward slope from one wall surface to the other wall surface;
a primary filling material injection step of injecting the filling material into the hole in such an amount that the filling material does not overflow from the opening of the hole even in a state in which the shear reinforcing member is inserted later;
a shear reinforcing member inserting step of inserting a shear reinforcing member into the hole into which the filler is injected;
a cap member installation step of installing a cap member having a filler injection port at a position higher than the upper edge of the opening in the opening of the hole after the shear reinforcing member is inserted;
a second filling material injection step of additionally injecting a filling material from the filling material injection port into the hole up to the upper edge of the opening after the cap member is installed ;
a cap member removing step of removing the cap member from the opening of the hole when the additionally injected filler solidifies to some extent;
Including .

According to the present invention, since the hole is drilled so as to have a downward slope with respect to the horizontal direction, it is possible to use a low-viscosity filler and facilitate injection.
In addition, since the hole is drilled so as to have a downward slope in the horizontal direction, by injecting it in two steps, before and after inserting the shear reinforcing member, it is possible to suppress the use of more filler than necessary, can be reliably filled.

Diagram showing the shear reinforcement area in an example of an underground box culvert A diagram showing a shear reinforcing structure applied to the LR section of FIG. Enlarged view of main part of Fig. 2 Process diagram showing the steps of the shear reinforcement method Diagram showing an example of the shape of the shear reinforcing member Explanatory diagram of cap installation process before secondary injection Front view and cross-sectional view of the cap member Explanation of dimensional relationship Diagram showing an example of shear reinforcement when drilling is possible from the inside and outside of the wall

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a cross-sectional view of an underground box culvert exemplified as a reinforcement object. In such a box culvert, it is effective to shear-reinforce the upper parts UL and UR and the lower parts LL and LR of the box culvert side walls 1, 1. It is said that

2 is a cross-sectional view showing a shear reinforcing structure applied to the LR portion in FIG. 1, and FIG. 3 is an enlarged view of a main part of FIG.

As can be seen from these figures, an existing reinforced concrete wall (for example, a box culvert side wall) 1 has a large number of vertical reinforcing bars 2a and horizontal reinforcing bars 2b along the inner wall surface 1a and inside by a specified cover thickness. It has an inner reinforcing bar 2 arranged in a lattice pattern, and an outer side in which a large number of vertical reinforcing bars 3a and horizontal reinforcing bars 3b are arranged in a lattice pattern along the outer wall surface 1b inside by a specified cover thickness. It has rebars 3.

Shear reinforcement for the existing reinforced concrete wall 1 is performed by post-installing bar-shaped shear reinforcement members 13 such as shear reinforcement bars.

Below, referring to FIG. 3 showing the final shear reinforcement structure and FIG. 4 showing the procedure of shear reinforcement, the shear reinforcement method for the existing reinforced concrete wall 1 will be described in the order of steps (1) to (4). ,explain.

(1) Drilling process As shown in Fig. 4 (1), a bottomed hole for inserting the shear reinforcing member 13 is installed in the existing reinforced concrete wall 1 from the inner wall surface 1a toward the outer wall surface 1b with a downward slope. A hole 11 is drilled.

When drilling the hole 11 here, the positions of the inner reinforcing bars 2 (longitudinal reinforcing bars 2a and horizontal reinforcing bars 2b), which are obstacles, are investigated in advance by an RC radar (reinforcement probe) or the like, so that the position where the inner reinforcing bars 2 are not present is detected. That is, holes are drilled obliquely downward with a hammer drill or the like, aiming at the central portion of the lattice formed by the vertical reinforcing bars 2a and the horizontal reinforcing bars 2b.

The tip of the hole 11 is made up to just before the outer reinforcing bar 3 so as not to damage the outer reinforcing bar 3 (vertical reinforcing bar 3a and horizontal reinforcing bar 3b) by drilling. It is desirable that the tip of the shear reinforcing member 13 reaches the outer reinforcing bar 3, but the position of the lattice of the outer reinforcing bar 3 (longitudinal reinforcing bars 3a and horizontal reinforcing bars 3b) cannot be known from the inner wall surface 1a side.
Therefore, the distance from the inner wall surface 1a to the outer reinforcing bar 3 is known from the design drawing at the time of construction of the reinforced concrete wall 1, and from this and the angle of the downward slope, the drilling length to the front of the outer reinforcing bar 3 is calculated, Drill holes based on this.

Regarding the diameter (drilling diameter) of the hole 11, for example, if the nominal diameter of the shear reinforcing reinforcing bar is D16 (the outermost diameter is 18 mm) and the diameter of the fixing portions (expanded diameter portions) at both ends is 27 mm, it is about 30 to 33 mm. do.

The downward slope angle of the hole 11 is in the range of 3° to 7°, for example, 5° with respect to the horizontal direction. 2 to 4, for drawing purposes, the diameter of the hole 11 is drawn relatively large compared to the wall thickness, so the downward slope angle of the hole 11 is drawn large.

After the completion of drilling, the inside of the hole 11 is cleaned by blowing off the drilling dust in the hole 11 using compressed air from an air compressor or the like.

(2) Filler Primary Injection Process As shown in FIG. 4(2), even when the shear reinforcing member is inserted into the hole 11 afterward, the amount of the filling material is such that it does not overflow from the opening 11a of the hole 11. amount, the filler (grout) 12 is injected.

As the filler 12, resin or cement milk (cement + water) is used. In particular, since the hole 11 has a downward slope and leakage can be prevented, a highly fluid (low viscosity) filling material 12 that is easy to inject can be used. For example, in the case of conventional horizontal drilling, if resin containing aggregate (glass) or mortar (cement + water + sand) is used as a filler, the downward slope allows the aggregate to be added. No resin or cement milk (cement + water) can be used.

(3) Shear reinforcing member inserting step As shown in FIG. 4(3), a rod-shaped shear reinforcing member (post-strike anchor) 13 such as a shear reinforcing reinforcing bar is inserted into the hole 11 into which the filler 12 is primarily injected. Push and insert.

As the shear reinforcing member 13, it is possible to suitably use a shear reinforcing bar having enlarged diameter portions for fixing at both ends thereof.
FIG. 5 shows an example of the shape of the shear reinforcing member 13, which can be implemented inexpensively. (A) shows a steel pipe attached to the end of a reinforcing bar by caulking. (B) is obtained by heating the ends of the reinforcing bars to about 800° C. and pressing them in the axial direction to expand them. (C) is obtained by heating the ends of the reinforcing bars to about 800° C. and bending them. (D) is a so-called straight bar, which is simply cut from raw rebar. Although (D) does not have an enlarged diameter portion, it has been experimentally confirmed that even a rectilinear muscle exerts a certain effect.

As the shear reinforcing member 13, although it is relatively expensive, it is used in the ceramic cap bar (CCb) construction method, and a ceramic fixing body (ceramic anchor) is attached to both ends of the shear reinforcing bar, or a post head bar ( A rectangular or circular plate or a joint attached to both ends of the shear reinforcement used in the PHb) construction method can also be used.

When the shear reinforcing member 13 is inserted into the hole 11 into which the filler 12 is primarily injected, the liquid surface of the filler 12 in the hole 11 reaches the vicinity of the lower edge of the opening 11a of the hole 11. .

(4) Filler secondary injection step As shown in FIG. 4(4), after inserting the shear reinforcing member 13, the filler 12 is additionally injected into the hole 11 up to the upper edge of the opening 11a, The hole 11 is filled with the filler 12 . In FIG. 4(4), the first injected filler is indicated as "12-1", and the secondarily injected filler is indicated as "12-2".

In order to ensure the additional injection of the filler 12 into the hole 11, between the shear reinforcing member inserting step (3) above and the filler secondary injection step (4) above, the following , a cap installation step may be provided.

(*) Cap installation process As shown in FIG. 6, after the shear reinforcement member insertion process and before the filler secondary injection process, the cap member 14 having the filler injection port 14b in the opening 11a of the hole 11. to be installed.
The filler injection port 14 b of the cap member 14 is provided at a position higher than the upper edge of the opening 11 a of the hole 11 .

FIG. 7 is a front view and cross-sectional view of the cap member.
The cap member 14 is mainly composed of a closing plate 14a made of steel or resin, which is applied to the opening surface of the hole 11 in the reinforced concrete wall and fixed by bolts 15 or the like. is protruded like a duck's mouth to form a filler injection port 14b at a position higher than the upper edge of the opening 11a of the hole 11. As shown in FIG.

Therefore, after the filling material 12 is primarily injected into the hole 11 and the shear reinforcing member 13 is inserted, the cap member 14 as shown in FIG. The filler 12 is additionally injected from the filler injection port 14b of 14. As shown in FIG. As a result, the hole 11 can be completely filled with the filler 12 up to the upper edge of the opening 11a.

After the additional injection of the filler 12, the cap member 14 is removed when the filler 12 is solidified to some extent. The removed cap member 14 can be diverted for secondary injection at other shear reinforcement locations.

The diameter of the hole 11, the downward slope angle, etc. will be described in more detail with reference to FIG.
The diameter (drilling diameter) d of the hole 11 is about 30 to 33 mm when the nominal diameter of the shear reinforcing reinforcing bar is D16 (outermost diameter 18 mm) and the diameter of the fixing portions (enlarged diameter portions) at both ends is 27 mm. .

The downward slope angle θ of the hole 11 is set to 3° to 7° (eg, 5°).
If the drilling width (the horizontal length of the hole 11) L is 1000 mm, the height difference H between both ends of the hole 11 is 52 mm (at 3°) to 122 mm (at 7°), and at 5° is 87 mm.

When drilling width L = 1000 mm, drilling diameter d = 30 mm, downgradient θ = 5°, and reinforcing bar nominal diameter D16, if the primary injection amount of the filler is 404 cc, insertion of the reinforcing bar (181 cc) will result in The liquid surface of the filler rises up to the lower edge of the opening.
Similarly, when drilling width L = 1000 mm, drilling diameter d = 36 mm, downward slope θ = 5°, and reinforcing bar nominal diameter D22, if the primary injection amount of the filler is 466 cc, the insertion of the reinforcing bar (342 cc) , the liquid surface of the filler rises up to the lower edge of the opening of the hole.

According to this embodiment, since the hole 11 for inserting the shear reinforcing member, which is subsequently constructed in a substantially horizontal direction, has a downward slope, it is possible to use a low-viscosity filler 12 with excellent fluidity. It can be poured from the drilled hole without an injection hose, and can be completely filled from the innermost part.

Further, according to the present embodiment, since no special equipment is required for filling the filler 12, the filler 12 can be continuously injected after many holes have been drilled and cleaned.

Further, according to this embodiment, since the shear reinforcing member 13, which is a post-strike anchor, is inserted into the filler 12, the adhesion is maintained reliably, and the operation of inserting the shear reinforcing member 13 is continuously performed. be able to.

Further, according to the present embodiment, the cap member 14 can be installed in a state in which the filler 12 does not overflow, and the secondary injection can be performed only by pouring the filler 12 from the filler injection port 14b on the upper side of the cap member 14. and the work is easy.

Further, according to the present embodiment, the filling material 12 basically does not overflow, and the filling material 12 is not wasted.

In the above embodiment, a method of construction from the inside of a box culvert side wall buried in the ground, etc., has been described.
In such a case, for example, as shown in FIG. 9, more effective reinforcement can be achieved by performing odd-numbered steps from the inside and even-numbered steps from the outside.
Of course, if it is possible to work only from the outside, it is possible to reinforce the structure from the outside by drilling bottomed holes with downward slopes from the outer wall surface to the inner wall surface.

In addition, it is possible to reinforce both sides of a structure having a rectangular cross section in plan view (long rectangular or elliptical in the direction perpendicular to the bridge axis) such as a bridge pier. In particular, piers should be reinforced from both sides (two directions) in the direction of the bridge axis. This is because such bridge piers often require reinforcement against shear forces in the direction of the bridge axis, and in many cases the width in the direction perpendicular to the axis is large and reinforcement is unnecessary.

Also, a substantially square or circular columnar structure in plan view may be reinforced from four directions.

It should be noted that the illustrated embodiment is only a schematic illustration of the present invention, and that the present invention, in addition to what is directly indicated by the described embodiment, can also be made by those skilled in the art within the scope of the claims. Needless to say, it includes the improvement and change of
The claims as originally filed were as follows.
[Claim 1]
A shear reinforcement method for reinforcing an existing reinforced concrete wall with a shear reinforcement member in post-construction,
A drilling step of drilling a bottomed hole for inserting a shear reinforcing member in an existing reinforced concrete wall at a downward slope from one wall surface to the other wall surface;
a primary filling material injection step of injecting the filling material into the hole in such an amount that the filling material does not overflow from the opening of the hole even in a state in which the shear reinforcing member is inserted later;
a shear reinforcing member inserting step of inserting a shear reinforcing member into the hole into which the filler is injected;
a second filling material injection step of additionally injecting a filling material into the hole up to the upper edge of the opening after the shear reinforcing member is inserted;
A method for shear reinforcement of a reinforced concrete wall, comprising:
[Claim 2]
After the shear reinforcing member insertion step and before the filler secondary injection step, a cap member having a filler injection port at a position higher than the upper edge of the opening is installed in the opening of the hole. 2. The method for shear reinforcement of a reinforced concrete wall according to claim 1, further comprising a step of installing a cap member.
[Claim 3]
3. The shear reinforcement method for a reinforced concrete wall according to claim 1, wherein said downward slope is in the range of 3° to 7° with respect to the horizontal direction.

1 Existing reinforced concrete wall (side wall of box culvert)
1a inner wall surface 1b outer wall surface 2 inner reinforcing bar (2a: vertical reinforcing bar, 2b: horizontal reinforcing bar)
3 outer reinforcing bar (3a: vertical reinforcing bar, 3b: horizontal reinforcing bar)
11 hole 11a opening 12 filler (12-1: primary filler, 12-2: secondary filler)
13 Shear reinforcing member (shear reinforcing bar)
14 cap member 14a closing plate 14b filling material inlet

Claims (4)

A shear reinforcement method for reinforcing an existing reinforced concrete wall with a shear reinforcement member in post-construction,
A drilling step of drilling a bottomed hole for inserting a shear reinforcing member in an existing reinforced concrete wall at a downward slope from one wall surface to the other wall surface;
a primary filling material injection step of injecting the filling material into the hole in such an amount that the filling material does not overflow from the opening of the hole even in a state in which the shear reinforcing member is inserted later;
a shear reinforcing member inserting step of inserting a shear reinforcing member into the hole into which the filler is injected;
a cap member installation step of installing a cap member having a filler injection port at a position higher than the upper edge of the opening in the opening of the hole after the shear reinforcing member is inserted;
a second filling material injection step of additionally injecting a filling material from the filling material injection port into the hole up to the upper edge of the opening after the cap member is installed ;
a cap member removing step of removing the cap member from the opening of the hole when the additionally injected filler solidifies to some extent;
A method for shear reinforcement of reinforced concrete walls , comprising: 2. The shear reinforcement method for a reinforced concrete wall according to claim 1, wherein in said shear reinforcement member inserting step, a shear reinforcement member provided with enlarged diameter portions at both ends thereof is inserted into said hole. The method for shear reinforcement of a reinforced concrete wall according to claim 1 or claim 2, wherein the downward slope is in the range of 3° to 7° with respect to the horizontal direction. The drilling step further includes drilling a bottomed hole for inserting a shear reinforcing member in the existing reinforced concrete wall from the other wall surface toward the one wall surface with a downward slope. The shear reinforcement method for a reinforced concrete wall according to any one of claims 1 to 3.

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