How to repair a hollow core slab

Abstract

To provide the repair method of a hollow slab allowing setting of precise form timbering to an opening formed in a void pipe simply in a short time.SOLUTION: The repair method of a hollow slab for repairing a repair region X including abnormal parts of concrete member thickness of a void upper part caused by floating up of a void pipe 1 comprises: an open-cut step of open-cutting floor slab concrete 4 of the repair region X; a manufacturing step of manufacturing a cylindrical body 2 having a form face formed on a side face and cut into multiple blocks in the axial direction; an assembling step of carrying in the cylindrical body 2 in every block from an opening 11 of the void pipe 1 formed by open-cut of the floor slab concrete 4 and assembling as a form timbering in the hollow part of the void pipe 1; and a placing step of placing concrete in the repair region X.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for repairing a hollow slab, which repairs defects in the thickness of a concrete member above a void caused by the lifting of a void pipe. [Background technology]

[0002] A hollow slab is a deck bridge with a hollow section inside, where void pipes are embedded to reduce weight. The void pipes can sometimes lift up on the top side of the hollow section when concrete is poured. If the void pipes lift up, they push up on the upper rebars, resulting in insufficient concrete cover for the rebars and insufficient thickness of the concrete components in the deck section, causing cracks and weakening in the deck section above the void pipes, which in turn causes cracks and potholes in the pavement surface.

[0003] Therefore, partial replacement is performed by excavating the abnormal part of the concrete material thickness above the void where the void pipe has risen abnormally, and re-placing it with concrete to a thickness that ensures the specified deck thickness. In this partial replacement, the circumferential surface of the void pipe is also scraped away during excavation, leaving an opening that leads to the hollow part. Therefore, when the concrete is replaced, it is necessary to close the opening that has formed in the void pipe and to use formwork support to support the concrete that is being poured for replacement. Urethane foam is filled in the hollow part of the void pipe and used as formwork support (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-146569 Summary of the Invention [Problem to be solved by the invention]

[0005] However, foam control is difficult when forming formwork supports using urethane foam, resulting in problems such as underfilled or overfilled areas and an uneven top surface of the formwork, which requires rework to be performed. Because of the risk of combustion, the urethane foam is filled after the repair rebar has been placed using a welding process or other method. Therefore, rework, such as shaping the top surface of the formwork, must be performed in a narrow space, making it difficult and time-consuming.

[0006] The present invention has been made in consideration of the above situation, and aims to solve the above-mentioned problems and provide a repair method for hollow slabs that allows accurate formwork support to be installed easily and quickly at openings formed in void pipes. [Means for solving the problem]

[0007] The repair method of the hollow hollow slab of the present invention is a method for repairing a repair area including an abnormal part of the concrete member thickness above the void caused by the void pipe floating, and includes an excavation step of excavating the deck concrete in the repair area; top surface The formwork surface is shaped in the axial direction. Extends to multiple pieces Cut into blocks and division The method is characterized by comprising a manufacturing process for manufacturing the cylindrical body, an assembly process for transporting the cylindrical body block by block through the opening of the void pipe created by excavating the deck concrete and assembling it as formwork support in the hollow part of the void pipe, and a pouring process for pouring concrete into the repair area. Furthermore, in the method for repairing a hollow slab of the present invention, the cylindrical body may be manufactured from a cylindrical polystyrene foam having an outer diameter equal to the inner diameter of the void pipe. Furthermore, the method for repairing a hollow slab of the present invention may include a sealing step of applying mortar to the form surface of the cylindrical body assembled as the form support to form a seal. Furthermore, in the method for repairing a hollow slab of the present invention, the existing deck reinforcing bars in the repair area may be removed before the assembly process, and new reinforcing bars may be placed after the sealing process. [Effects of the Invention]

[0008] According to the present invention, by simply assembling a cylindrical body in the hollow portion of a void pipe, accurate formwork support can be easily and quickly installed in the opening formed by the void pipe. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the configuration of a cylindrical body used in a method for repairing a hollow slab according to the present invention. FIG. [Figure 2] 2A to 2C are diagrams illustrating a manufacturing process for the cylindrical body shown in FIG. [Figure 3] 2 is a cross-sectional view of the ZZ cross section shown in FIG. [Figure 4] 1A and 1B are diagrams showing the repair process of a hollow slab. [Figure 5] FIG. 1 is an explanatory diagram illustrating the repair process of a hollow slab. [Figure 6] FIG. 1 is an explanatory diagram illustrating the repair process of a hollow slab. [Figure 7] 2 is a diagram showing an example of division of the cylindrical body shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, a mode for carrying out the present invention (hereinafter simply referred to as an "embodiment") will be specifically described with reference to the drawings. In the following embodiments, components having similar functions will be assigned the same reference numerals and descriptions thereof will be omitted as appropriate.

[0011] In the repair method for hollow slabs of this embodiment, referring to Figure 1, when excavating and repairing a repair area X including an abnormal location in the thickness of the concrete member above the void, a cylindrical body 2 is used as a form support to be installed in the opening 11 formed by the void pipe 1. The cylindrical body 2 has an outer diameter equal to the inner diameter of the void pipe 1 and a flat form surface 3 on its side, and is installed without gaps sufficient to serve as a form support. In Figure 1, (a) is a top view, and (b) is a YY cross-sectional view shown in (a).

[0012] The cylinder 2 is made from a cylindrical polystyrene foam 20, as shown in Figure 2(a), whose outer diameter is the same as the inner diameter of the void pipe 1. The cylindrical polystyrene foam 20 is cut along the full length D along the cutting line shown by the dotted line in Figure 2(a), to form the cylinder 2 with the formwork surface 3.

[0013] The axial length of the polystyrene foam 20 used is longer than the length L1 of the opening 11 of the void pipe 1 in the bridge axis direction. Therefore, the length L3 of the formwork surface 3 is formed longer than the length L1 of the opening 11 of the void pipe 1 in the bridge axis direction. The width W3 of the formwork surface 3 is also formed to be longer than the width W1 (length perpendicular to the bridge axis) of the opening 11 of the void pipe 1.

[0014] As shown in Figure 3, the repair area X is set as a predetermined area including an abnormal area A where the thickness of the deck concrete 4 on the top surface of the void pipe 1 does not meet the design value (hereinafter referred to as the void top design value) due to the lifting of the void pipe 1. In the bridge axis direction, the repair area X is an area sandwiched between normal areas B that meet the void top design value. Note that when the repair area X is set to include normal areas B in the bridge axis direction, both ends of the repair area X in the bridge axis direction become normal areas B.

[0015] Even if the repair area X is excavated in the normal area B or its vicinity, the void pipe 1 will not form an opening 11. Therefore, the opening 11 of the void pipe 1 will have a curved shape at both ends in the bridge axis direction, as shown in Figure 1(a), and will not match the formwork surface 3, which has been formed into a rectangle by the D-cut. The length L1 of the opening 11 in the bridge axis direction is the length of the longest central part.

[0016] However, as mentioned above, the length L3 of the formwork surface 3 is longer than the length L1 of the opening 11 in the bridge axis direction, so by pushing in both ends of the shrinkable cylinder 2, the cylinder 2 can be installed without any gaps, sufficient to serve as formwork support, even at both ends of the opening 11 in the bridge axis direction.

[0017] The cylinder 2 is cut in the axial direction along the cutting lines shown by the dotted lines in Fig. 2(b), and as shown in Fig. 2(c), is divided into a plurality of blocks each large enough to pass through the opening 11 of the void tube 1. In this embodiment, an example in which the cylinder 2 is divided into seven blocks is shown, but there is no limit to the number of blocks as long as they can pass through the opening 11 of the void tube 1.

[0018] The cylinder 2 is carried into the hollow part of the void pipe 1 through the opening 11 in each divided block, assembled in the hollow part, and placed as formwork support in the hollow part of the void pipe 1. The cylinder 2 is placed so that the formwork surface 3 coincides with the opening 11 formed in the void pipe 1.

[0019] Next, the repair process of this embodiment will be described in detail with reference to FIGS. 4, the first repair process involves restricting traffic in the repair area X shown in Figures 5(a) and 5(b) (S01). In Figure 5, (a) is a front view, and (b) is a cross-sectional view taken along the line XX shown in (a).

[0020] In the next repair process, as shown in Figures 5(c) and (d), the asphalt pavement 5 and the deck concrete 4 in the repair area X are removed using a water jet (S02, S03), exposing the existing deck reinforcing bars 6 in the bridge axis direction and the existing deck reinforcing bars 7 in the direction perpendicular to the bridge axis. In Figure 5, (c) is a top view, and (d) is a cross-sectional view taken along the line XX shown in (c).

[0021] The deck concrete 4 is excavated to a depth equal to or greater than the void upper surface design value. Therefore, the upper surface of the void pipe 1 in the repair area X is damaged by the excavation using the water jet, and an opening 11 is formed.

[0022] The next repair process involves cutting and removing the existing deck reinforcing bars 6 and 7 in the repair area X, and then investigating the dimensions of the remaining reinforcing bars (S04). Also, the dimensions of the opening 11 formed in the void pipe 1 are investigated (S05).

[0023] The next repair process is to lay steel plates in the excavated repair area X, restore the area with temporary paving (S06), and then lift the traffic restrictions (S07). The above steps S01 to S07 are the repair process for the first day.

[0024] The repair process until the next work day involves processing and adjusting new rebars based on the investigation of the remaining rebars carried out in S04 (S08), and manufacturing the cylinder 2 based on the investigation of the opening 11 of the void pipe 1 carried out in S05 (S09). The manufacturing of the cylinder 2 is carried out according to the procedure shown in Fig. 2, but if the repair area X is reduced in diameter at the end of the void pipe 1 or if the void pipe 1 is deformed, the outer surface may be processed.

[0025] The first repair process on the second day involves restricting traffic in the repair area X (S10) and removing the temporary pavement and steel plates (S11).

[0026] In the next repair process, the cylinders 2 manufactured in S09 are transported in blocks through the openings 11 of the void pipe 1 and assembled in the hollow space, as shown in Figure 1 (S12). The cylinders 2 are placed in the hollow space of the void pipe 1 as formwork support by aligning the formwork surface 3 with the openings 11 formed in the void pipe 1. Because the cylinders 2 are shaped to fit the inner diameter of the void pipe 1, they can be installed tightly enough as formwork support to ensure the required strength, and the finished shape is less dependent on the skill of the workers. Furthermore, because the cylinders 2 are made of lightweight polystyrene foam, installation does not require large-scale equipment and can be easily assembled by hand. Furthermore, because the cylinders 2 are pre-formed, they do not require curing to develop strength like urethane foam. Furthermore, because the cylinders 2 are made of polystyrene foam, which is easy to process, even workers without special skills can easily do so by using electric heating wires.

[0027] The next repair process involves applying fast-hardening mortar to the formwork surface 3 of the cylinder 2 to form a non-combustible seal 8 (S13), as shown in Figures 6(a) and (b), with the aim of integrating the assembled cylinder 2 and finishing the formwork surface 3. In Figure 6, (a) is a front view, and (b) is a cross-sectional view taken along the line XX shown in (a).

[0028] As shown in Figures 6(c) and (d), the next repair process involves assembling and arranging the new rebars processed and adjusted in S08 and connecting them to the existing deck rebars 6, 7 by enclosed welding or the like (S14). In Figure 6, (c) is a front view, and (d) is a cross-sectional view taken along the line XX shown in (c). Since a non-combustible seal 8 is formed on the formwork surface 3 of the cylinder 2, welding using fire can be performed after the cylinder 2 is installed. In other words, the cylinder 2 can be assembled while maintaining the working space required before assembling the new rebars.

[0029] The next repair process is to pour quick-hardening concrete (S15) as formwork support for the cylindrical body 2. After the poured concrete has hardened, asphalt paving is applied (S16), traffic restrictions are lifted, and the repair work is completed.

[0030] In this embodiment, all blocks of the divided cylinder 2 are assembled using void pipes 1, thereby ensuring the strength and stability of the formwork support. The number of divisions into which the cylinder 2 is divided and the division method are arbitrary. Furthermore, if the strength and stability are within an acceptable range, not all of the divided blocks need to be used. For example, FIG. 7(a) shows an example in which the cylinder 2 is divided into seven blocks, five of which are used. FIG. 7(b) shows an example in which the cylinder 2 is divided into six blocks, four of which are used. In these cases, the number of blocks to be assembled using the void pipes 1 can be reduced, thereby reducing the assembly man-hours.

[0031] As described above, this embodiment is a method for repairing a hollow slab, which repairs a repair area X including an abnormal area in the thickness of the concrete material above the raised void in the void pipe 1, and includes an excavation process (S03) for excavating the concrete deck 4 in the repair area X, a manufacturing process (S09) for manufacturing a cylindrical body 2 having a formwork surface 3 formed on its side and cut into multiple blocks in the axial direction, an assembly process (S12) for transporting the cylindrical body 2 block by block through the opening 11 in the void pipe 1 created by excavating the concrete deck 4 and assembling them as formwork supports in the hollow part of the void pipe 1, and a pouring process for pouring concrete into the repair area X. With this configuration, by simply assembling the cylinder 2 in the hollow part of the void pipe 1, accurate formwork support can be easily and quickly installed in the opening 11 formed in the void pipe 1. By using a pre-formed cylinder 2, there is no need for curing to develop strength, as is the case with urethane foam.

[0032] Furthermore, in this embodiment, the cylindrical body 2 is manufactured from a cylindrical polystyrene foam 20 having an outer diameter equal to the inner diameter of the void tube 1. With this configuration, the shape is matched to the inner diameter of the void pipe 1, so by installing it without any gaps to a sufficient extent as formwork support, the required strength can be ensured, and the finished shape is less dependent on the skill of the workers. Also, since the cylinder 2 is made of lightweight polystyrene foam, no large-scale equipment is required for installation, and it can be easily transported and assembled by hand. Furthermore, since the cylinder 2 is made of polystyrene foam, which is easy to process, even workers without special skills can easily do it by using an electric heating wire, etc.

[0033] Furthermore, this embodiment includes a sealing step (S13) of applying mortar to the form surface 3 of the cylindrical body 2 assembled as a form support in the hollow portion of the void pipe 1 to form a seal 8. This configuration allows the assembled cylindrical body 2 to be integrated, and also allows the form surface 3 to be finished.

[0034] Furthermore, in this embodiment, before the assembly process, the existing deck reinforcing bars 6, 7 in the repair area X are removed (S04), and after the sealing process, new reinforcing bars 9 are placed (S14). This configuration allows the assembly of the cylinder 2 to be performed while ensuring a working space before assembling the new reinforcing bars. In addition, since the non-combustible seal 8 is formed, welding using fire can be performed safely after the cylinder 2 is installed.

[0035] The present invention has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in terms of the combination of the respective components, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0036] 1. Void tube 2 Cylinder 3 Formwork surface 4. Deck concrete 5. Asphalt pavement 6 Existing deck reinforcing bars 7 Existing deck reinforcing bars 8 Seals 9 Newly installed rebar 20 Styrofoam

Claims

1. A repair method for a hollow slab that repairs a repair area including an abnormality in the thickness of a concrete member above a void caused by the floating of a void pipe, An excavation step of excavating the deck concrete in the repair area; a manufacturing process for manufacturing a cylindrical body having a mold surface formed on an upper surface thereof, which is cut and divided into a plurality of axially extending blocks; An assembly process in which the cylindrical body is carried in blocks through the opening of the void pipe created by excavating the deck concrete, and assembled as a formwork support in the hollow portion of the void pipe; A method for repairing a hollow slab, comprising: a pouring step of pouring concrete into the repair area.

2. 2. The method for repairing a hollow slab according to claim 1, wherein the cylindrical body is manufactured from a cylindrical polystyrene foam having an outer diameter equal to the inner diameter of the void pipe.

3. A method for repairing a hollow slab as described in claim 1 or 2, characterized in that it includes a sealing process in which mortar is applied to the formwork surface of the cylindrical body assembled as the formwork support to form a seal.

4. Before the assembly process, remove the existing deck reinforcing bars in the repair area, 4. The method for repairing a hollow slab according to claim 3, wherein new reinforcing bars are arranged after the sealing step.

Images