Reinforcement structure and reinforcing method

Abstract

To provide a reinforcement structure, etc. that can suitably reinforce the foundation of a pillar member with lining concrete.SOLUTION: A reinforcement structure 1 reinforces a pier 2 provided on a footing 3. Existing lining concrete 4 is provided around the pier 2, and axial reinforcing bars 41 are embedded inside the lining concrete 4 along the axial direction of the pier 2. In the reinforcement structure 1, a thickness increasing portion 5 of the footing 3 is provided above the footing 3 at a height corresponding to the lower part of the lining concrete 4 so as to surround the lining concrete 4, and a cut portion 43 is provided below the lining concrete 4, where the axial reinforcing bars 41 are cut.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reinforcement structure for a pillar member. [Background technology]

[0002] A method of reinforcing existing bridge piers is known in which concrete is wrapped around the periphery of the pier and axial reinforcing bars are embedded in the concrete (for example, Patent Document 1). This makes it possible to improve the strength of stepped-down sections in the axial middle of the pier. Stepped-down sections are sections in the pier where the number of main bars is reduced. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6427045 Summary of the Invention [Problem to be solved by the invention]

[0004] When the weight of the superstructure of a bridge increases due to widening of the superstructure, etc., it may be necessary to reinforce the foundation to prevent bending of the pier with the above-mentioned wrapped concrete.

[0005] In the case of foundation pile structure, a footing made of reinforced concrete is rigidly connected to the bottom end of the pier, and this footing is supported by piles in the ground, but it is difficult to reinforce the reinforcing bars in the footing, especially the reinforcing bars on the bottom side, later to prevent bending of the pier and footing. Therefore, it is possible to thicken the footing to ensure the effective height for the reinforcing bars on the bottom side, but in this case, the lower part of the axial reinforcing bars in the existing wrapped concrete will be included in the thickened part of the footing as a fixed structure, and the base strength of the pier will increase, which may lead to an undesirable failure mode in which the stepped part of the pier will yield first. It is wasteful to provide additional reinforcement at the stepped part to prevent such a failure mode, and it is often difficult to provide reinforcement to ensure the necessary strength.

[0006] The present invention has been made in consideration of the above problems, and aims to provide a reinforcing structure etc. that can suitably reinforce the foundation of a column member having encased concrete. [Means for solving the problem]

[0007] The first invention for solving the above-mentioned problems is a reinforcing structure for a column member based on a footing, characterized in that existing encased concrete is provided around the column member, axial reinforcing bars along the axial direction of the column member are buried inside the encased concrete, a thickened portion of the footing is provided above the footing at a height that corresponds to the lower part of the encased concrete so as to surround the encased concrete, and a cut portion is provided at the lower part of the encased concrete by cutting the axial reinforcing bars.

[0008] In this invention, the footing of the column member having the concrete encased in concrete is thickened to reinforce the foundation, and the lower part of the axial rebar in the concrete encased in concrete is cut. This prevents the part deeper than the cut part from becoming an anchoring structure in the thickened part of the footing, and prevents the base strength of the pier from becoming too large. As a result, it is possible to prevent the step-down part of the pier from yielding first, which is an undesirable form of failure, and to avoid the need for additional reinforcement in the step-down part.

[0009] The cut portion is, for example, cut into a slit shape in the axial reinforcing bar together with the lining concrete from outside the lining concrete, and it is also preferable that the cut portion is filled with a hardening material. It is also preferable that the cut portion is formed obliquely with respect to the horizontal direction over the entire circumference of the lining concrete so as to become lower toward the column member side, and that an injection hole for injecting the hardening material and a discharge hole for discharging the hardening material are formed in a part of the circumferential direction of the lining concrete at the cut portion. The cut portion can be easily formed by a cutter or the like. In addition, by filling the cut portion with a solidifying material, it is possible to prevent the cut portion from exhibiting unstable behavior due to bending, compression, etc. By forming the cut portion at an angle as described above and providing an injection hole and a discharge hole for the solidifying material, it is possible to easily and reliably fill the solidifying material.

[0010] It is desirable that the cut portion be located deeper than the upper surface of the thickened portion. This prevents the cut portion from coming into contact with the outside air, and prevents deterioration of the reinforcing structure from the cut portion.

[0011] It is desirable that the axial reinforcement is not anchored to the footing located below the thickened portion. In this case, the state in which the axial rebars are not fixed remains unchanged before and after the footing is thickened, so it is possible to prevent the base strength of the pier from changing before and after the footing is thickened.

[0012] The second invention is a reinforcing method for reinforcing the foundation of a column member that is established on a footing, comprising the steps of: providing existing encased concrete around the column member; embedding axial reinforcing bars along the axial direction of the column member inside the encased concrete; and forming an increased thickness of the footing on top of the footing at a height that corresponds to the lower part of the encased concrete so as to surround the encased concrete; and cutting the axial reinforcing bars at the lower part of the encased concrete to form a cut portion. A second invention is a reinforcing method for reinforcing a foundation using the reinforcing structure of the first invention. Effect of the Invention

[0013] The present invention can provide a reinforcing structure that can suitably reinforce the foundation of a column member having wrapped concrete. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 shows a reinforcing structure 1. [Diagram 2] FIG. 1 shows a reinforcing structure 1. [Diagram 3] FIG. [Figure 4] A diagram showing a horizontal cross section of a bridge pier 2 and encased concrete 4. [Diagram 5] FIG. 4 is a diagram showing cut portions 43 and 43a. [Figure 6] A diagram showing the angled cut 43 and the injection hole 431. [Figure 7] FIG. 4 shows the cutting portion 43, the injection hole 431, and the discharge hole 432. [Figure 8] FIG. 4 is a diagram for explaining a method of filling the solidification material 44. [Figure 9] 13 is an example in which a height difference is provided in the circumferential direction of the lining concrete 4 at the cut portion 43. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0016] (1. Reinforcement structure 1) Fig. 1 is a schematic diagram of a reinforcement structure 1 according to an embodiment of the present invention. This reinforcement structure 1 reinforces a footing 3 of an existing bridge pier 2, and Fig. 1 shows a cross section of the pier 2 taken along its width direction.

[0017] The foundation of the pier 2 is realized by a foundation pile structure. That is, a footing 3 is rigidly attached to the lower part of the pier 2, and the footing 3 is supported from below by piles (not shown) in the ground. However, the foundation is not limited to this, and it is sufficient if it has a footing 3. For example, a spread foundation may be used.

[0018] The pier 2 is a column member made of reinforced concrete that is installed on the footing 3, and has reinforcing bars (not shown) such as main bars installed inside. The footing 3 is a plate-shaped member made of reinforced concrete, and has reinforcing bars (not shown) such as horizontal reinforcing bars installed inside.

[0019] On the outer periphery of the pier 2, lining concrete 4 is provided to surround the pier 2 in order to reinforce the stepped-down portion located in the middle of the pier 2 in the axial direction. Inside the lining concrete 4, axial reinforcing bars 41 aligned along the axial direction of the pier 2 and circumferential reinforcing bars 42 aligned along the circumferential direction of the pier 2 are provided.

[0020] Furthermore, in this embodiment, concrete is poured on top of the footing 3 at a height corresponding to the lower part of the lining concrete 4 so as to surround the lining concrete 4, forming a thickened portion 5 of the footing 3. In the reinforcement structure 1 of this embodiment, the footing 3 is thickened by this thickened portion 5, and the effective height from the horizontal reinforcing bars (not shown) on the underside of the footing 3 is secured, thereby reinforcing the foundation.

[0021] FIG. 2 is a diagram showing the details of the reinforcement structure 1, and is an enlarged view of the range A in FIG. 1. In this embodiment, a cut portion 43 is provided by cutting the axial reinforcing bars 41 together with the lining concrete 4 into a slit shape with a cutter or the like and removing them together with the lining concrete 4 at a position deeper than the upper surface of the thickened portion 5 below the lining concrete 4. The thickness of the cut portion 43 is about 5 mm, but is not limited to this. A solidifying material 44 such as mortar or resin is filled in the cut portion 43. The height at which the cut portion 43 is provided is near the upper surface of the thickened portion 5, is about 80 to 120 mm lower than the upper surface to ensure the cover, and is a location that avoids the height of the circumferential reinforcing bars 42, but is not limited to this.

[0022] In addition, in this embodiment, the axial reinforcing bars 41 in the encased concrete 4 are not embedded or fixed in the (existing) footing 3 below the thickened portion 5, and the lower ends of the axial reinforcing bars 41 are located on the upper surface of the footing 3 or at a higher position.

[0023] (2. Reinforcement method) Fig. 3 is a diagram for explaining a method for forming (reinforcing) the reinforcement structure 1. In this embodiment, for a pier 2 in a state in which lining concrete 4 is provided as shown in Fig. 3(a), first, as shown in Fig. 3(b), the lower part of the lining concrete 4 and the axial reinforcing bars 41 are cut in a slit shape to form a cut portion 43.

[0024] Fig. 4(a) is a diagram showing a horizontal cross section of a pier 2 and the surrounding lining concrete 4. As shown in Fig. 4(a), a plurality of axial reinforcing bars 41 are arranged at intervals in the circumferential direction of the pier 2, and are provided around the entire circumference of the lining concrete 4. In the process of Fig. 3(b) described above, a cut portion 43 is formed around the entire circumference of the lining concrete 4, as shown in Fig. 4(b). Note that reference numeral 411 in Fig. 4(b) indicates the cut surface of the axial reinforcing bars 41.

[0025] The cutting portion 43 can be formed, for example, by using a cutter that moves on rails provided on each side of the concrete lining 4, but is not limited to this. It is also possible to use a fiberscope inserted into the cutting portion 43 to check whether the axial reinforcing bars 41 have been cut.

[0026] After forming the cut portion 43 in this manner, as shown in Fig. 3(c), the slit-shaped cut portion 43 is filled with a solidifying material 44, reinforcing bars (not shown) and the like are placed on the footing 3, and concrete is poured to form the thickened portion 5 as shown in Fig. 2 etc. Through the above-mentioned procedure, reinforcement by the reinforcing structure 1 is performed.

[0027] According to the reinforcing structure 1 of this embodiment, when reinforcing the foundation by thickening the footing 3 of the pier 2 having the lining concrete 4, the lower part of the axial reinforcing bars 41 in the lining concrete 4 is cut. This prevents the part deeper than the cut part 43 from becoming an anchoring structure in the thickened part 5 of the footing 3, and makes it possible to prevent the bearing capacity of the base of the pier 2 (cross section at the top surface of the thickened part 5) from becoming too large.

[0028] As a result, it is possible to prevent the step-down portion of the pier 2 from yielding first, which is an undesirable form of destruction, and to avoid the need for additional reinforcement in the step-down portion, etc. Even if additional reinforcement is required, a minor configuration can be achieved, and construction will not be difficult.

[0029] In addition, the cut portion 43 in this embodiment is formed by cutting the axial reinforcing bar 41 together with the lining concrete 4 into a slit shape, and can be easily formed by a cutter or the like. In addition, by filling the cut portion 43 with the solidification material 44, it is possible to prevent the cut portion 43 from exhibiting unstable behavior due to bending compression or the like.

[0030] Furthermore, in this embodiment, since the axial reinforcing bars 41 are not originally fixed to the footing 3, the state in which the axial reinforcing bars 41 are not fixed remains unchanged before and after the thickening of the footing 3. Therefore, it is possible to prevent the base strength of the pier 2 from changing before and after the thickening of the footing 3, and it is possible to make the base strength of the pier 2 almost unchanged from the base (cross section at the top surface of the footing 3) of the pier 2 when it is newly constructed.

[0031] However, the present invention is not limited to the above embodiment. For example, the cut portion 43 in this embodiment is located deeper than the upper surface of the thickened portion 5, which prevents the cut portion 43 from being exposed to the outside air and prevents deterioration of the reinforcement structure 1 from the cut portion 43, but as shown in Fig. 5(a), the cut portion 43 may be located higher than the upper surface of the thickened portion 5 at the bottom of the lining concrete 4. In this case, the cut portion 43 can be formed in the lining concrete 4 after the thickened portion 5 is formed.

[0032] The method of forming the cut portion 43 is not limited to the above, and the lining concrete 4 may be chipped out and the axial reinforcing bars 41 may be gas-cut, or the lower portion of the lining concrete 4 may be removed and the lower portion of the axial reinforcing bars 41 may be cut and removed, as shown in cut portion 43a of Fig. 5(b). Also, only a portion of the axial reinforcing bars 41 in the lining concrete 4 may be cut.

[0033] 6(a), the cut portion 43 may be formed at an angle to the horizontal direction so as to become lower toward the pier 2, which can improve the fluidity of the solidification material 44. In the example of FIG. 6(a), the cut portion 43 is formed so as to reach from the outer surface of the lining concrete 4 to a position between the axial reinforcing bar 41 and the pier 2 in the thickness direction of the lining concrete 4. The inclination angle of the cut portion 43 is, for example, about 15°, but is not limited to this.

[0034] Fig. 7 is a diagram showing a horizontal cross section of the lining concrete 4 at the height of the outer opening of the cut section 43. As shown in Fig. 7, the cut section 43 is formed over the entire circumference of the lining concrete 4, but an injection hole 431 and a discharge hole 432 for the solidification material 44 are formed in the cut section 43 in a part of the circumferential direction of the lining concrete 4.

[0035] FIG. 6(b) shows a cross section of the injection hole 431 similar to that of FIG. 6(a). The injection hole 431 is a hole having a circular cross section, and its diameter is, for example, about 20 mm, which is larger than the thickness of the cut portion 43 (for example, about 5 mm). The injection hole 431 can be formed by drilling the lining concrete 4 with a hammer drill or the like. The injection hole 431 is provided at the same height and inclination as the cut portion 43 so that the position of the end of the injection hole 431 on the pier 2 side coincides with the position of the end of the cut portion 43 on the pier 2 side. The discharge hole 432 is also formed in the same manner as the injection hole 431. In the example of FIG. 7, the injection hole 431 is provided at a position corresponding to a pair of corners on a diagonal line of the square-shaped cross section of the lining concrete 4, and the discharge hole 432 is provided at a position corresponding to a pair of corners on another diagonal line.

[0036] When filling the solidification material 44, as shown in FIG. 8(a), the outer opening of the cut section 43 (except the positions corresponding to the injection hole 431 and the discharge hole 432) is blocked with a strip-shaped seal 45, the tip of a nozzle 46 for injecting the solidification material 44 is inserted into the injection hole 431, and the solidification material 44 is injected from the injection hole 431 with a predetermined injection pressure. The solidification material 44 flows down through the injection hole 431 and then flows into the cut section 43, and as shown in FIG. 8(b), the solidification material 44 is filled in order from the end of the cut section 43 on the pier 2 side toward the outer opening. Along with this, the air in the cut section 43 is discharged from the discharge hole 432, and it is confirmed that the solidification material 44 is finally discharged from the discharge hole 432, and the filling work of the solidification material 44 is completed. This makes it possible to easily and reliably fill the solidification material 44.

[0037] It is desirable to use a solidification material 44 with low viscosity so that the solidification material 44 flows smoothly and fills the cut portion 43. For example, when using mortar as the solidification material 44, the viscosity should be such that the JP funnel time (seconds) according to the Japan Society of Civil Engineers standard JSCE-F531-2018 is 3.5 (seconds) or more and 40 (seconds) or less, and when using resin, the viscosity (mPa·s) specified in JIS A 6024:2015 is 100 (mPa·s) or more and 10,000 (mPa·s) or less.

[0038] For example, packing tape can be used as the seal 45 (formwork), but a steel plate may also be used as the formwork depending on the pressure acting from the solidification material 44. The formwork may also be transparent so that the filling status of the solidification material 44 can be visually observed from the outside.

[0039] 9, the cut portion 43 may be provided with a height difference in the circumferential direction of the lining concrete 4, which allows the solidification material 44 to be filled reliably. In this case, the injection hole 431 is provided at a lower position, and the discharge hole 432 is provided at a higher position. A similar height difference can also be provided when the cut portion 43 is formed horizontally as in FIG. 5(a).

[0040] Furthermore, there is no particular limitation on the shape, configuration, etc., of the pier 2. For example, the pier 2 is not limited to a rectangular plane as shown in Fig. 4, but may be a circular plane or an oval plane. In this case, the lining concrete 4 and the cut portion 43 are formed in a ring shape so as to surround the pier 2, and a wire saw or the like can be used to form the cut portion 43.

[0041] Furthermore, the application of the reinforcement structure 1 is not limited to bridge piers 2, but the reinforcement structure 1 can be applied to reinforce various types of pillar members.

[0042] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to the above examples. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the technical ideas disclosed in this application, and it is understood that these also naturally belong to the technical scope of the present invention. [Explanation of symbols]

[0043] 1: Reinforcement structure 2: Bridge pier 3: Footing 4: Concrete wrapping 5: Thickened section 41: Axial reinforcement 43, 43a: Cutting section 44:Solidification material 431: Injection hole 432: Discharge hole

Claims

1. A reinforcement structure for a column member provided on a footing, Existing concrete is provided around the pillar member, An axial reinforcing bar is embedded in the inside of the concrete along the axial direction of the column member, The thickened portion of the footing is provided on the footing at a height that corresponds to the lower part of the lining concrete so as to surround the lining concrete, A reinforcement structure characterized in that a cut portion is provided in the lower part of the wrapped concrete, where the axial steel bar is cut.

2. 2. The reinforcement structure according to claim 1, wherein the cut portion is formed by cutting the axial reinforcing bar together with the encased concrete into a slit shape from outside the encased concrete.

3. 3. The reinforcement structure according to claim 2, wherein the cut portion is filled with a solidifying material.

4. The cut portion is formed obliquely with respect to the horizontal direction over the entire circumference of the lining concrete so as to become lower toward the column member side, The reinforcement structure according to claim 3, characterized in that an injection hole for injecting the solidification material into the cut portion and a discharge hole for discharging the solidification material are formed in a portion of the circumferential direction of the wrapped concrete in the cut portion.

5. 2. The reinforcement structure according to claim 1, wherein the cut portion is located deeper than an upper surface of the thickened portion.

6. 2. The reinforcement structure according to claim 1, wherein the axial reinforcement is not anchored to the footing located below the thickened portion.

7. A method for reinforcing a foundation of a column member provided on a footing, comprising the steps of: Existing concrete is provided around the pillar member, An axial reinforcing bar is embedded in the inside of the concrete along the axial direction of the column member, The method includes forming a thickened portion of the footing on the footing at a height that is in contact with a lower portion of the lining concrete so as to surround the lining concrete, A reinforcing method comprising the steps of: cutting the axial reinforcing bar at a lower portion of the encased concrete to form a cut portion.

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