Dismantlement method

Abstract

To provide a demolition method which can easily dismantle an existing CFT column.SOLUTION: The demolition method executes, upon dismantling a CFT column 1, the steps of: drilling holes 11 on a side face of a steel tube 10 in the CFT column 1; forming core holes 21 in concrete 20 at the inside of the steel tube 10 at positions corresponding to the holes 11; dividing the concrete 20 into upper and lower parts using explosives or a non-explosive crushing agent arranged at the core holes 21; and dividing the steel tube 10 into upper and lower parts after the division of the concrete 20 into upper and lower parts.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for disassembling a concrete-filled steel tube column.

Background Art

[0002] A concrete-filled steel tube column (hereinafter referred to as a CFT column) is a column in which concrete is filled inside a steel tube. When disassembling a CFT column, for example, a wire saw is used to cut the steel tube and the concrete simultaneously.

[0003] Further, in Patent Document 1, it is described that the disassembly of a CFT column is performed by melting the steel tube and breaking the concrete, and by previously providing a combustible or highly porous material on the inner peripheral portion of the steel tube at the time of manufacturing the CFT column, the melting operation of the steel tube is made more efficient.

[0004] Furthermore, in Patent Document 2, after preventing the CFT column from falling by a wire, the steel tube is cut by a cutting mechanism that moves along a ring-shaped guide rail, and a lateral force or a bending force is applied to the CFT column by using mechanical forces such as a jack, a lever lock, and a heavy machine, thereby breaking the concrete at the cut portion of the steel tube. A disassembly method is described.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the conventional method of disassembling using a wire saw, it takes time to install the wire saw and cut the steel pipe and concrete simultaneously. Also, during the simultaneous cutting of the steel pipe and concrete, it is necessary to perform the operation while suspending the CFT column with a crane so that it does not fall, which takes a long time to occupy the crane and compresses the construction period.

[0007] Also, in the method of Patent Document 1, it is necessary to previously provide a material having combustibles or voids on the inner peripheral portion of the steel pipe during the manufacture of the CFT column, which takes time for the manufacture of the CFT column. Also, it cannot be applied to existing CFT columns without materials having combustibles or voids.

[0008] In the method of Patent Document 2, since the concrete of the CFT column is broken to be segmented, although the CFT column is prevented from falling by a wire or the like, it is greatly overloaded and there is a concern of colliding with surrounding machinery and equipment, scaffolds, workers, etc., and appropriate attention is required for safe construction.

[0009] The present invention has been made in view of the above problems, and an object thereof is to provide a disassembling method capable of easily disassembling an existing CFT column.

Means for Solving the Problems

[0010] The present invention for solving the above-described problems is a method for disassembling a concrete-filled steel pipe column, comprising: a step of making a hole in a side surface of the steel pipe of the concrete-filled steel pipe column; a step of forming a core hole in the concrete inside the steel pipe at a position corresponding to the hole; a step of using explosives or non-explosive crushing agents disposed in the core hole to segment the concrete vertically; and a step of segmenting the steel pipe vertically after segmenting the concrete vertically.

[0011] In the present invention, the concrete inside the steel pipe can be easily segmented by the crushing force of explosives or non-explosive crushers. Also, when the concrete is segmented, the steel pipe serves as a curing material substitute, preventing the generation of noise, vibration, and dust. Moreover, since the load-bearing capacity of the CFT column when segmenting the concrete is sufficiently ensured by the steel pipe, there is no need to suspend and support the CFT column with a crane or the like until the steel pipe is segmented, and the occupation time of the crane can be significantly shortened. From the above, in the present invention, the CFT column can be easily disassembled, and the disassembly cost can also be reduced.

[0012] After vertically segmenting the steel pipe, it is desirable to lift the concrete portion above the segmentation location of the concrete and the steel pipe portion above the segmentation location of the steel pipe by a crane. Thereby, the segmented concrete portion and steel pipe portion can be lifted by a crane and easily removed.

[0013] The cross-section of the steel pipe is rectangular, and some of the plurality of core holes are formed along the side surface of the steel pipe. When segmenting the steel pipe, it is desirable to perform gas cutting of the steel pipe on the side surface. Due to the crushing force of explosives or non-explosive crushers loaded in the core holes along the side surface of the steel pipe, the steel pipe can be bulged in the out-of-plane direction to form a gap with the concrete. This gap significantly improves the efficiency when gas-cutting and segmenting the steel pipe.

[0014] The cross-section of the steel pipe is rectangular, and all of the plurality of core holes may be formed to extend from one side surface of the steel pipe to the vicinity of the side surface opposite to the one side surface. Thereby, all the core holes can be formed by working on one side surface of the steel pipe, improving the working efficiency.

[0015] Using a plugging material arranged outside the steel pipe along the side surface of the steel pipe, the concrete may be segmented vertically by the explosives or non-explosive crushers with the plurality of core holes plugged. As a result, the crushing force generated by the explosives and non-explosive crushing agents loaded in the core holes can be surely applied to the concrete, and the amount of explosive charge can be reduced. In addition, the scattering of fillings and glass can be prevented by the plugging material.

Effect of the Invention

[0016] According to the present invention, a disassembling method capable of easily disassembling an existing CFT column can be provided.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 8

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Figure 10

Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0019] (1. CFT column 1) FIG. 1 is a diagram showing the CFT column 1 to be disassembled by the disassembling method according to the embodiment of the present invention.

[0020] The CFT column 1 is a column (concrete-filled steel tube column) with concrete 20 filled inside a steel pipe 10. In this embodiment, its horizontal cross-section (hereinafter sometimes simply referred to as cross-section) is rectangular. However, the shape of the cross-section is not limited to this, and for example, it may be circular. Also, the dimensions of the cross-section are not particularly limited.

[0021] (2. Demolition method of CFT column 1) In this embodiment, the CFT column 1 is divided by a substantially horizontal dividing line, and the divided CFT column 1 is lifted and removed by a crane. First, the floor height of the dividing line is determined. The height of the dividing line is considered in light of the working posture of the workers, the lifting capacity of the crane, the constructability of the lifting work, etc.

[0022] Then, as shown in FIG. 2, at the height of the dividing line a of the CFT column 1, holes 11 are drilled in the side surface of the steel pipe 10. A plurality of holes 11 (three in the example of the figure) are provided at intervals in the width direction of the side surface of the steel pipe 10. The holes 11 can be formed by drilling tools such as an atora or a core drill or by gas cutting. The diameter of the holes 11 is, for example, 30 mm or more, and the height of the dividing line a from the floor slab 3 is, for example, about 1000 mm, but it is not limited to this.

[0023] Next, as shown in FIG. 3(a), at a position corresponding to the holes 11 of the steel pipe 10, horizontal core holes 21 are formed in the concrete 20 inside the steel pipe 10. The core holes 21 are formed using a core drill having a diameter slightly smaller than that of the holes 11.

[0024] FIG. 3(b) is a view showing a cross-section along the dividing line a of the CFT column 1. A plurality of (three in the example of the figure) core holes 21 are formed in parallel so as to extend from one side surface 101 of the steel pipe 10 to the vicinity of the side surface 102 opposite to the one side surface 101. Also, in this embodiment, the CFT column 1 is provided at the outer peripheral portion of the floor slab 3, and in order to facilitate the formation work of the core holes 21, the above-mentioned one side surface 101 is used as the side surface on the indoor side. The side surface 102 opposite to the one side surface 101 is the side surface outside the building (floor slab 3).

[0025] In this embodiment, subsequently, as shown in FIG. 4, detonating cord 4, which is an explosive, is loaded into the portion from the inner depth of core hole 21 to the front of the open end of core hole 21, and filler 5 such as wet sand is packed from the end on the open end side of detonating cord 4 to inside hole 11 of side surface 101 of steel pipe 10. Then, the detonating cords 4 in a plurality of core holes 21 are detonated almost simultaneously to generate horizontal cracks in concrete 20 within steel pipe 10, and concrete 20 is divided vertically at the height of dividing line a.

[0026] Note that the number of holes 11 and core holes 21 is determined according to the cross-sectional dimensions of CFT column 1 and the like. Also, regarding the spacing between core holes 21, appropriate values vary according to the arrangement of core holes 21 and the like. For example, in the example of FIG. 3(b) where a plurality of core holes 21 are arranged in parallel at the center of the cross-section of CFT column 1, it is desirable that the spacing between core holes 21 be at least about 200 mm. By appropriately setting the spacing between core holes 21, even when the detonating cords 4 of adjacent core holes 21 are detonated with a minute time difference, the detonating cord 4 of the adjacent core hole 21 will not be cut off and become misfired due to the detonation of the preceding detonating cord 4. Since the detonating energy is less likely to escape when the detonating cord 4 is closer to the inner surface of core hole 21, the diameter of core hole 21 is considered in view of the amount of charge.

[0027] After dividing concrete 20 vertically, as shown in FIG. 5, while suspending and supporting the column head portion of CFT column 1 with a suspending member such as wire W hanging down from a crane (not shown), the entire circumference of steel pipe 10 is cut along dividing line a, so that steel pipe 10 is divided at dividing location 12 along dividing line a. Then, the concrete portion above the dividing location of concrete 20 and the steel pipe portion above dividing location 12 of steel pipe 10 are lifted and removed by a crane. The cutting of steel pipe 10 is performed by gas cutting, but a machine such as a wire saw may also be used. Also, the heights of the dividing locations of concrete 20 and dividing location 12 of steel pipe 10 may be slightly different.

[0028] In this embodiment, the beam end portion 2 is connected to the column head portion of the CFT column 1, and the column head portion of the CFT column 1 is supported by suspending the beam end portion 2 from a crane. Although the beam end portion 2 is separated from the remaining portion of the beam, the steel pipe 10 may be cut while the beam end portion 2 is continuous with the remaining portion of the beam before separating the beam end portion 2.

[0029] As described above, in this embodiment, the concrete 20 inside the steel pipe 10 can be easily cut by the crushing force of the detonating cord 4. Also, when the concrete 20 is cut, the steel pipe 10 serves as a curing material substitute to prevent the generation of noise, vibration, and dust. Further, since the load-bearing capacity of the CFT column 1 when cutting the concrete 20 is sufficiently ensured by the steel pipe 10, it is not necessary to suspend and support the CFT column 1 with a crane or the like until the steel pipe 10 is cut, and the occupancy time of the crane can be significantly shortened. From the above, in this embodiment, the CFT column 1 can be easily disassembled and the disassembly cost can be reduced.

[0030] Also, in this embodiment, after cutting the concrete 20 vertically, the steel pipe 10 is cut vertically, and the cut concrete portion and steel pipe portion can be easily removed by suspending them with a crane.

[0031] Also, in this embodiment, all the core holes 21 can be formed by working on one side surface 101 of the steel pipe 10, and since the working surface does not need to be changed each time, the working efficiency is improved. Also, since the extending directions of the core holes 21 are aligned, the core holes 21 do not interfere with each other in plan view and can be provided at the same level, and the height of the cutting portion of the concrete 20 can be appropriately controlled near the cutting line a.

[0032] However, the present invention is not limited to the above-described embodiments. For example, in the above embodiment, the concrete 20 is divided by the explosion of the detonating cord 4, but the detonating cord 4 may be replaced with other explosives such as water-containing explosives or emulsion explosives, or non-explosive crushers. However, since the water-containing explosive is a gel-like explosive, it is suitable for filling the core holes 21 densely, but since the amount of explosive charged depends on the diameter of the core holes 21, it is difficult to adjust the amount of explosive. In addition, since the non-explosive crusher does not fall under the category of explosives under the Explosives Control Law, it is convenient for use and storage, but since the blasting energy per unit amount is inferior to that of explosives, the amount of explosive increases and the cost rises, or the core holes 21 have a large diameter and construction work becomes cumbersome. Also, since it is in powder form, it is necessary to transfer it to another container to adjust the amount of explosive.

[0033] Also, in the present embodiment, all the core holes 21 are provided from one side surface 101 of the steel pipe 10, but as shown in FIG. 6(a), the core holes 21 may be formed from each of a pair of opposing side surfaces 103 and 104 toward the opposite side surfaces 104 and 103. Also in this case, when the CFT column 1 is at the outer peripheral portion of the floor slab 3, it is desirable that the side surfaces 103 and 104 be the indoor-side side surfaces. When the CFT column 1 is inside the outer peripheral portion of the floor slab 3, as shown in FIG. 6(b), relatively short core holes 21 may be formed from all the side surfaces 101 to 104 of the steel pipe 10. In the example of FIG. 6(b), there are sets of core holes 21 that are orthogonal. In this case, the separation between these core holes 21 (the minimum distance between the core holes 21. In particular, in the example of FIG. 6(b), the distance between the tips of the core holes 21) is desirably at least about 40 to 50 mm. Further, in the example of FIG. 6(b), depending on the lengths of the side surfaces 101 to 104, there may be a case where a plurality of core holes 21 are provided in parallel from the same side surfaces 101 to 104. Also in this case, the separation between the parallel core holes 21 is desirably at least about 40 to 50 mm.

[0034] Also, as shown in Fig. 7, before detonating the detonating cord 4, a plugging material 8 may be arranged to plug each core hole 21 (and hole 11) formed from the side surface 103 of the steel pipe 10. The plugging material 8 is a horizontal material arranged outside the steel pipe 10 along the side surface 103 of the steel pipe 10, and is fixed to the side surface 103 by a fixing material 9. By using the plugging material 8 to direct the gas generated by the detonation of the detonating cord 4 towards the crushing of the concrete 20 without allowing it to escape outside, it becomes possible to horizontally divide the concrete 20 with a smaller amount of explosive charge. Also, by preventing the scattering of the filling material 5 and debris, the detonation can be carried out more safely.

[0035] The fixing material 9 has a pressing material 91 and a connecting material 92. The pressing material 91 is a horizontal material arranged along the side surface 104 facing the side surface 103 of the steel pipe 10. Both ends of the plugging material 8 and the pressing material 91 protrude laterally from the side surfaces 103 and 104 of the steel pipe 10 respectively, and the connecting material 92 connects both ends of the plugging material 8 and the pressing material 91 to each other. Thereby, the steel pipe 10 is clamped by the plugging material 8 and the pressing material 91, and the plugging material 8 is pressed against and fixed to the steel pipe 10 side. Steel materials such as H-shaped steel are used for the plugging material 8 and the pressing material 91, but it is not limited thereto. In this case as well, when the CFT column 1 is at the outer peripheral part of the floor slab 3, it is desirable that the above-mentioned side surfaces 103 and 104 be the indoor-side side surfaces. This is for facilitating the formation work of the core holes 21 and the installation work of the plugging material 8 and the fixing material 9.

[0036] Also, as shown in Fig. 8(a), in addition to the above-mentioned core holes 21 (see Fig. 4 etc.), core holes 21 may be further formed along the side surfaces 102, 103, 104 of the steel pipe 10, and blasting may be carried out by the detonating cord 4a loaded in these core holes 21. Due to the impact of the blasting, the side surfaces 102, 103, 104 of the steel pipe 10 can be made to bulge out of the plane as shown in Fig. 8(b), creating a gap between the steel pipe 10 and the concrete 20. Note that Fig. 8(b) shows a vertical cross-section in the thickness direction of the steel pipe 10 regarding the state after the blasting of the detonating cord 4a. In the example of Fig. 8(a), the core hole 21 provided from the side surface 101 and the core hole 21 provided along the side surface 102 are orthogonal, but the separation between these core holes 21 (the distance between the tip of the former core hole 21 and the latter core hole 21) is at least about 40 to 50 mm. Also, the separation between the core holes 21 provided along the side surfaces 103, 104 and the adjacent core holes 21 (the core hole 21 provided from the side surface 101) is also at least about 40 to 50 mm.

[0037] As described above, creating a gap between the steel pipe 10 and the concrete 20 using the detonating cord 4a loaded in some of the core holes 21 is for smoothly performing gas cutting at the fracture location 12 of the steel pipe 10 (see Fig. 8(b)). That is, in gas cutting, the steel material (steel pipe 10) heated by the gas flame becomes iron oxide by being supplied with oxygen at high speed from the center of the burner of the cutting machine, and the iron oxide with a lower melting point than steel is blown away by the oxygen jet, thereby cutting the steel pipe 10. Therefore, when there is no gap between the steel pipe 10 and the concrete 20, the cutting efficiency decreases because the momentum of the oxygen jet is reflected by the concrete 20 and weakened. On the other hand, when a gap is formed between the steel pipe 10 and the concrete 20, the oxygen jet is not reflected by the concrete 20, so the momentum of the jet does not weaken and the cutting efficiency improves.

[0038] The blasting of the detonating fuse 4a is carried out in the same process as the blasting of the detonating fuse 4, but the amount of the detonating fuse 4a can be less compared to the amount of the detonating fuse 4 for dividing the concrete 20. Therefore, the diameter of the core hole 21 for loading the detonating fuse 4a can also be made smaller compared to the core hole 21 for loading the detonating fuse 4. In this case as well, when the CFT column 1 is at the outer peripheral portion of the floor slab 3, it is desirable to form each core hole 21 from the indoor side surfaces 101 and 104 of the steel pipe 10.

[0039] In the present invention, the concrete 20 is divided vertically by the blasting of the detonating fuse 4, but it is also possible to crush and divide the concrete 20 by a heavy machine or the like. In this case as well, the CFT column 1 can be easily disassembled. In this case, as shown in Fig. 9(a), core holes 21 are formed along the side surfaces 103 and 104 of the steel pipe 10, and by the blasting of the detonating fuse 4a loaded in the core holes 21, the side surfaces 103 and 104 of the steel pipe 10 are made to bulge out of the plane as shown in Fig. 9(b).

[0040] Then, the steel pipe 10 is gas cut at the upper and lower cutting positions b (see Fig. 9(b)), and the portion between the cutting positions b of the steel pipe 10 is removed in a strip shape. The removal of the steel pipe 10 is performed on the three side surfaces 101, 103, and 104 of the steel pipe 10, and for one side surface 102, the steel pipe 10 is left without being removed. Also, in the example of Fig. 9(a), the detonating fuse 4a is loaded in the core holes 21 along the two side surfaces 103 and 104 of the steel pipe 10, and since these side surfaces 103 and 104 are made to bulge out of the plane, for one side surface 101 out of the three side surfaces 101, 103, and 104 where the gas cutting of the steel pipe 10 is performed, the gas cutting is performed without making the steel pipe 10 bulge out of the plane.

[0041] The gas cutting of the steel pipe 10 is performed while suspending and supporting the column head portion of the CFT column 1 with a suspension member such as a wire W suspended from a crane as shown in Fig. 10(a), and then, the concrete 20 exposed at the removed portion of the steel pipe 10 is crushed by a heavy machine or the like. When the concrete 20 is crushed, the CFT column 1 tilts to the side opposite to the side surface 102 where the steel pipe 10 is left as shown in Fig. 10(b). Then, the steel pipe 10 on the side surface 102 is cut, and the CFT column 1 above the crushed portion of the concrete 20 is lifted by a crane.

[0042] By leaving the steel pipe 10 on one side surface 102 of the steel pipe 10, the direction in which the CFT column 1 falls during the crushing of the concrete 20 is defined, preventing the CFT column 1 from falling in an irregular direction, and improving the safety of the operation. In the examples of FIGS. 9 and 10, the CFT column 1 is arranged on the outer peripheral portion of the floor slab 3, and by setting the side surface 102 where the steel pipe 10 is left as the outer side surface of the building (floor slab 3), the direction in which the CFT column 1 falls is defined toward the indoor side.

[0043] As described above, the preferred embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those skilled in the art can conceive of various modification examples or correction examples within the scope of the technical idea disclosed in this application, and it is naturally understood that those also belong to the technical scope of the present invention.

Explanation of Reference Numerals

[0044] 1: CFT column 4, 4a: Detonating cord 5: Filling 8: Plugging material 9: Fixing material 10: Steel pipe 11: Hole 20: Concrete 21: Core hole

Claims

1. A method for disassembling a concrete-filled steel tube column, comprising: drilling a hole in a side surface of the steel tube of the concrete-filled steel tube column; forming a core hole in the concrete inside the steel tube at a position corresponding to the hole; using explosives or non-explosive crushers disposed in the core hole to divide the concrete vertically; after dividing the concrete vertically, dividing the steel tube vertically; The disassembling method is characterized by comprising the above steps.

2. The disassembling method according to Claim 1, wherein after dividing the steel tube vertically, the concrete portion above the dividing portion of the concrete and the steel tube portion above the dividing portion of the steel tube are lifted by a crane.

3. The cross section of the steel tube is rectangular, a part of the plurality of core holes are formed along the side surface of the steel tube, when dividing the steel tube, gas cutting of the steel tube is performed on the side surface. The disassembling method according to Claim 1 is characterized by this.

4. The cross section of the steel tube is rectangular, all of the plurality of core holes are formed so as to extend from one side surface of the steel tube to the vicinity of the side surface opposite to the one side surface. The disassembling method according to Claim 1 is characterized by this.

5. The disassembling method according to Claim 1, wherein using a plugging material disposed outside the steel tube along the side surface of the steel tube, with the plurality of core holes plugged, the concrete is divided vertically by the explosives or non-explosive crushers.

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