JP7519945B2 - Reinforcement method for concrete structures and reinforced structures - Google Patents

Description

The present invention relates to a method for reinforcing concrete structures such as bridge piers and rigid-frame viaducts, and to a reinforced structure.

Conventionally, the sheet pile reinforcement method has been widely adopted as a method for reinforcing existing concrete structures, such as the piers of railway and road bridges or rigid-frame viaducts. The sheet pile reinforcement method involves driving steel sheet piles around the perimeter of the existing structure and adding a new footing between the existing structure and the steel sheet piles, thereby integrating the steel sheet piles with the existing structure, thereby improving the resistance of the structure and increasing its stability.

Conventionally, a method for integrating concrete structures such as footings, pier bodies, and underground beams with steel sheet piles has been to cast anchors into the concrete structure and then fix the reinforcing bars attached to the steel sheet pile in the additional footing. For example, Patent Document 1 discloses a structure in which a perforated steel plate is welded to the steel sheet pile and the reinforcing bars are fixed in the holes in the perforated steel plate as a method for attaching the reinforcing bars to be fixed in the additional footing to the steel sheet pile.

Patent Document 2 also discloses a joint structure in which a connecting material is installed between a structure such as a foundation and a steel sheet pile, both ends of the connecting material are connected to the structure and the steel sheet pile, and a filler is filled between the structure and the steel sheet pile.

JP 2006-57251 A JP 2007-51485 A

However, when installing anchors between the existing concrete and steel sheet pile, as in the structure described in Patent Document 1, it is necessary to ensure a gap of about 1.2 to 1.5 m between the steel sheet pile and the existing concrete, and this gap becomes the width of the additional footing. When additional footings are provided around existing bridge piers, rigid frame viaducts, etc. in this way, the footing width after reinforcement may become too large and violate the site boundary, so it is desirable to minimize lateral expansion, especially when the site is narrow.

On the other hand, if an additional footing is provided on the upper surface to prevent the footing width from increasing, the upper surface of the additional footing may protrude above the ground surface. In urban areas in particular, it is not desirable to have the additional footing protrude above the ground surface in order to make effective use of land.

In addition, in the case of the joint structure described in Patent Document 2, in order to join the connecting material and the steel sheet pile, work such as bolt tightening is required between the existing footing and the steel sheet pile, which is time-consuming and requires sufficient space to perform the work.

The present invention was made in consideration of the above circumstances, and aims to provide a reinforcement method that suppresses the expansion of the width of a concrete structure, and a reinforced structure reinforced by this method.

In order to solve the above problems, the present invention is a method for reinforcing a concrete structure, which comprises casting a reinforcing member onto the outer periphery of the concrete structure, casting an anchoring member from the outer periphery of the reinforcing member so as to be fixed to both the reinforcing member and the concrete structure to integrate them, filling the gap between the reinforcing member and the concrete structure with a filler, the anchoring member being a post-installed anchor to be driven into the concrete structure and a reinforcing bar having one end fixed to the outer periphery of the reinforcing member, the post-installed anchor and the reinforcing bar being overlapped within the gap, the reinforcing member being a steel sheet pile, and the reinforcing bar being fixed to the web and flange of the steel sheet pile .

The filler may be concrete.

It is preferable to cover the fixing member fixed to the outer periphery of the reinforcing member with a covering material.

It is preferable that a hole for inserting the fixing member be formed in the reinforcing member before casting.
An anchoring portion may be provided at one end of the reinforcing bar, and the other end of the reinforcing bar may be configured in a hook shape.
A reinforcing bar cage may be disposed in the gap between the reinforcing member and the concrete structure.

The present invention also provides a reinforced structure that is reinforced by the above-mentioned reinforcement method.

According to the present invention, since the fixing members are driven from the outer periphery of the reinforcing member, there is no need to leave a large space between the reinforcing member and the concrete structure to install the fixing members, and excess expansion of the structure after reinforcement can be suppressed. Therefore, construction can be done even on a narrow site.

1A and 1B are front views of a reinforced structure according to an embodiment of the present invention, in which (a) shows the case where a footing of a bridge pier is reinforced, and (b) shows the case where an underground beam of a rigid frame viaduct is reinforced. 2A is an enlarged cross-sectional view of part A in FIG. 1, where (a) shows a case where a reinforcing bar having an anchoring portion is used, (b) shows a case where the base end of the reinforcing bar is welded, and (c) shows a case where a U-shaped reinforcing bar is used. FIG. 2 is a perspective view showing an example of a reinforcing bar having an anchoring portion. FIG. 2 is an enlarged cross-sectional view showing a different embodiment of part A in FIG. 1 . 1A and 1B are cross-sectional views showing examples of steel sheet piles, in which FIG. 1A shows a U-shaped steel sheet pile and FIG. 1B shows a hat-shaped steel sheet pile. 1A and 1B are cross-sectional views showing examples of a connection between a concrete structure and a steel sheet pile, in which (a) shows the case where a U-shaped steel sheet pile is used, and (b) shows the case where a hat-shaped steel sheet pile is used. 1A and 1B are cross-sectional views showing different examples of a connection portion between a concrete structure and a steel sheet pile, in which (a) shows a case where a U-shaped steel sheet pile is used, and (b) shows a case where a hat-shaped steel sheet pile is used. 5A and 5B are cross-sectional views showing further different examples of a connection portion between a concrete structure and a steel sheet pile, in which (a) shows a case where a U-shaped steel sheet pile is used, and (b) shows a case where a hat-shaped steel sheet pile is used. FIG. 2 is a diagram illustrating an example of a construction procedure of a reinforcement method according to an embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals to avoid redundant description.

The present invention is mainly applied when reinforcing existing concrete structures, such as existing footings, bridge pier bodies, and underground beams of rigid-frame viaducts. Figure 1 shows a reinforced structure 1 that is an example of an embodiment of the present invention, with Figure 1(a) showing a case in which the concrete structure 2 to be reinforced is an existing footing of a bridge pier, and Figure 1(b) showing an example in which the concrete structure 2 is an underground beam of a rigid-frame viaduct.

As shown in Figure 1, steel sheet piles 3 are cast as reinforcing members into the ground around a concrete structure 2 that requires reinforcement. Holes are formed in the steel sheet piles 3 for inserting reinforcing bars as anchoring members, and reinforcing bars 4 inserted from the outer periphery of the steel sheet piles 3 are driven into the concrete structure 2, integrating the steel sheet piles 3 and the concrete structure 2.

2 is an enlarged view of part A in FIG. 1, showing an example of a method of fixing the reinforcing bar 4 to the steel sheet pile 3. FIG. 2(a) shows an example in which the fixing portion 11 provided at one end of the reinforcing bar 4 is abutted against the outer peripheral surface of the steel sheet pile 3. The shape of the fixing portion 11 is not limited, and it can be, for example, a circular or rectangular plate-shaped fixing portion 11a, 11b as shown in FIG. 3. FIG. 2(b) shows an example in which one end of the reinforcing bar 4 is bent into an L-shape and the bent end abuts along the outer peripheral surface of the steel sheet pile 3, and the abutted end of the reinforcing bar 4 is welded to the steel sheet pile 3 by, for example, flare welding. FIG. 2(c) shows an example in which the reinforcing bar 4 is a U-shaped reinforcing bar, and both ends are driven into the concrete structure 2. In this way, the reinforcing bars 4 are fixed to both the existing concrete structure 2 and the steel sheet pile 3, and the gap between the steel sheet pile 3 and the concrete structure 2 is filled with the filler 5, integrating the concrete structure 2 and the steel sheet pile 3. As the filler 5, concrete, mortar, or other existing filler materials can be used. In addition, a reinforcing bar cage can be placed at an appropriate interval in the gap between the steel sheet pile 3 and the concrete structure 2 to increase the rigidity of the gap as an additional footing.

Figure 4 shows a different example of a method of fixing the concrete structure 2 and the steel sheet pile 3. A post-installed anchor 6 is attached to the concrete structure 2 through a hole 12 formed in the steel sheet pile 3, and the reinforcing bar 4 inserted from the steel sheet pile 3 and the post-installed anchor 6 are overlapped between the steel sheet pile 3 and the concrete structure 2, and these become the fixing members. Concrete 7 for providing additional footing or filling concrete is poured between the steel sheet pile 3 and the concrete structure 2. In this embodiment, the post-installed anchor 6 on the concrete structure 2 side and the reinforcing bar 4 on the steel sheet pile 3 side are fixed to the concrete 7, respectively, so that the concrete structure 2 and the steel sheet pile 3 are integrated. In this case, the reinforcing bar 4 fixed to the steel sheet pile 3 may have an anchoring portion 11, one end bent into an L-shape, or a U-shape, as in the example shown in Figure 2. The diameter and number of the reinforcing bar 4 may be any diameter and number that is necessary for the additional footing or filling concrete portion in normal structural calculations. In this case, a reinforcing bar cage can also be placed between the existing concrete structure 2 and the steel sheet pile 3 to increase the rigidity of the additional footing, but if this is not necessary, the reinforcing bar cage can be omitted and only concrete can be used to prevent the footing width from expanding.

In Figures 1(a) and (b), the dotted lines indicate the position of the steel sheet pile when using conventional construction methods. In the case of a structure in which a perforated steel plate is welded to a steel sheet pile and reinforcing bars are fixed, as in Patent Document 1 and the like, a width of about 1.2 to 1.5 m of additional footing is required for construction. In contrast, according to the present invention, in the embodiment shown in Figure 2, the gap between the steel sheet pile 3 and the existing concrete structure 2 is extremely small. Even in the embodiment shown in Figure 4, a gap of about 0.6 m is enough to ensure the anchorage length of the reinforcing bars 4 and the post-installed anchors 6, and a sufficient reinforcement structure can be constructed. In other words, in either case, the expansion of the width of the reinforcement structure 1 can be suppressed more than in the past.

The shape of the steel sheet pile 3 used in the above embodiment is not limited, and various commercially available steel sheet piles can be applied. Figure 5 shows an example of a typical steel sheet pile. For example, a U-shaped steel sheet pile 3a having a web 13 and a flange 14 as shown in Figure 5(a) or a hat-shaped steel sheet pile 3b having a web 13, a flange 14, and an arm 15 as shown in Figure 5(b) can be used.

The location where the reinforcing bars 4 are fixed to the steel sheet pile 3 is basically the position of the web 13 in both steel sheet piles 3a and 3b, as shown in Figure 6 (a) (for U-shaped steel sheet piles) and Figure 6 (b) (for hat-shaped steel sheet piles). However, if the amount of reinforcing bars is insufficient with the web 13 alone, they may be fixed to the flange 14 or arm 15. In addition, in a severe corrosive environment, it is preferable to cast a coating material 8 that covers the outside of the steel sheet piles 3a and 3b for corrosion prevention, as shown in Figure 6. However, when the reinforcing bars 4 are fixed only to the web 13 of the recessed part of the U-shaped steel sheet pile 3a as shown in Figure 7 (a), or when the reinforcing bars 4 are fixed to the web 13 of the hat-shaped steel sheet pile 3b as shown in Figure 7 (b), the coating material 8 may be provided only in the area that covers the reinforcing bars 4 in the recessed part, and in this case, the coating material 8 can prevent the width of the reinforced structure 1 from expanding. The covering material 8 is made of concrete, mortar, or a urethane-based coating material that has anti-corrosive properties.

Figure 8 shows an example of pouring concrete 7 between the steel sheet pile 3 and the concrete structure 2 to provide an additional footing or filler concrete. The anchoring points of the reinforcing bars 4 to the steel sheet piles 3a and 3b and the covering material 8 are the same as in the embodiment of Figure 6.

Below, an example of the construction procedure for a reinforcement structure according to an embodiment of the present invention will be described with reference to Figure 9.

First, steel sheet piles 3 are driven into the ground around a concrete structure 2, such as the existing footing of a bridge pier that requires reinforcement or the underground beam of a rigid-frame viaduct, and a gap 21 between the steel sheet pile 3 and the concrete structure 2 is excavated and retained (Figure 9(a)). The steel sheet piles 3 are driven by a commonly used pressure-in method. It is preferable that holes 12 for inserting reinforcing bars 4, post-installed anchors 6, etc. are formed in the steel sheet piles 3 before they are driven.

Next, foundation concrete 22 is poured into the bottom of the excavated area (Figure 9(b)).

Then, excavate the outer periphery of the steel sheet pile 3 to secure space 23 for installing reinforcing bars 4 and post-installed anchors 6 (Figure 9 (c)).

Next, holes are drilled in the concrete structure 2 from the holes 12 on the outer periphery of the steel sheet pile 3, and the reinforcing bars 4 are inserted and fixed (Figure 9(d)). When fixing the reinforcing bars 4 in the filling concrete or additional footing (see Figure 4), after drilling the concrete structure 2, post-installed anchors 6 are attached from the holes 12 on the outer periphery of the steel sheet pile 3, and the reinforcing bars 4 are inserted and placed along the post-installed anchors 6 to form a lap joint.

Then, filler is filled into the gap between the concrete structure 2 and the steel sheet pile 3 (Figure 9 (e)). When filling concrete or providing an additional footing, an appropriate gap is ensured between the concrete structure 2 and the steel sheet pile 3, and concrete is poured. When providing an additional footing, a reinforcing bar cage is placed as necessary before pouring the concrete.

Then, unnecessary parts of the upper end of the steel sheet pile 3 are cut off, and the excavated area is backfilled to complete the reinforced structure 1 (Figure 9(f)).

As described above, according to the present invention, since reinforcing bars 4 and post-installed anchors 6 are inserted through holes 12 on the outer periphery of the steel sheet pile 3, there is no need to provide space between the steel sheet pile 3 and the concrete structure 2 for inserting anchors, etc. This makes it possible to reduce the distance between the steel sheet pile 3 and the concrete structure 2, thereby preventing the width of the reinforced structure 1 from increasing. Therefore, even if the site is narrow, the existing concrete structure 2 can be reinforced. In addition, since expensive perforated steel plate dowels are no longer necessary, costs can be reduced.

The above describes preferred embodiments of the present invention, but the present invention is not limited to these examples. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

For example, while the above embodiment has been described as an example of reinforcing an existing concrete structure, the present invention can also be applied to newly constructed structures.

The reinforcing member that is integrated with the concrete structure 2 is preferably a member with a flat surface, but is not limited to the steel sheet pile 3 described in the above embodiment. For example, a similar reinforcing method can be implemented with a steel pipe sheet pile, etc.

The present invention is useful as a method for reinforcing concrete structures such as the footings of railway and road bridge piers and the underground beams of rigid-frame viaducts.

Reference Signs List 1 Reinforcement structure 2 Concrete structure 3 Steel sheet pile 3a U-shaped steel sheet pile 3b Hat-shaped steel sheet pile 4 Reinforcement bar 5 Filling material 6 Post-installed anchor 7 Concrete 8 Covering material 11 Anchorage 12 Hole 13 Web 14 Flange 15 Arm

Claims (7)

A method for reinforcing a concrete structure, comprising the steps of:
A reinforcing member is cast on the outer periphery of the concrete structure,
An anchoring member is driven into the outer periphery of the reinforcing member so as to be fixed to both the reinforcing member and the concrete structure and to integrate them together;
Filling the gap between the reinforcing member and the concrete structure with a filler,
The fixing member is a post-installed anchor to be driven into the concrete structure and a reinforcing bar having one end fixed to the outer peripheral surface of the reinforcing member, and the post-installed anchor and the reinforcing bar are overlapped in the gap,
The reinforcing member is a steel sheet pile,
A method for reinforcing a concrete structure, comprising fixing the reinforcing bar to the web and flange of the steel sheet pile . The method for reinforcing a concrete structure according to claim 1, characterized in that the filler is concrete. The method for reinforcing a concrete structure according to claim 1 or 2, characterized in that the fixing member fixed to the outer periphery of the reinforcing member is covered with a covering material. The method for reinforcing a concrete structure according to any one of claims 1 to 3, characterized in that the reinforcing member has holes formed therein for inserting the fixing member before casting. The method for reinforcing a concrete structure according to any one of claims 1 to 4, characterized in that an anchoring portion is provided at one end of the reinforcing bar, and the other end of the reinforcing bar is configured in a hook shape. 5. The method for reinforcing a concrete structure according to claim 1, further comprising disposing a reinforcing bar cage in a gap between the reinforcing member and the concrete structure. A reinforced structure, characterized in that it is reinforced by the reinforcing method according to any one of claims 1 to 6 .

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