Demolition method

Abstract

To provide a demolition method capable of easily demolishing an existing CFT column.SOLUTION: When a CFT column 1 in which concrete 20 is filled in a steel pipe 10 having a polygonal cross section is demolished, there are performed the steps of: laying and arranging the CFT column 1 removed from an installation place in a demolition place 2; forming a core hole 4 along a second surface adjacent to a first surface of the steel pipe 10 in the concrete 20 inside the steel pipe 10 from a hole 3 formed in the first surface of the steel pipe 10 of the laid and arranged CFT column 1 and arranging a detonating cord 5 in the core hole 4; and separating the second surface from the concrete 20 using the detonating cord 5.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for dismantling a concrete-filled steel pipe column. [Background technology]

[0002] Concrete-filled steel pipe columns (hereafter referred to as CFT columns) are columns in which concrete is filled inside a steel pipe. When demolishing a CFT column, the steel pipe and concrete must be separated. For this reason, the sides of the steel pipe are cut and removed using gas cutting or other methods, exposing the concrete inside, which is then crushed using demolition machinery.

[0003] Patent Document 1 also describes that CFT columns are dismantled by gas fusing of the steel pipes and destruction of the concrete, and that the efficiency of the fusing work of the steel pipes is improved by providing a flammable or highly porosity material on the inner periphery of the steel pipes beforehand during the manufacture of the CFT columns. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-212511 Summary of the Invention [Problem to be solved by the invention]

[0005] Because the adhesion strength between the steel pipes and concrete in CFT columns is strong, conventional demolition methods do not allow for complete removal of the concrete using heavy machinery alone; concrete remaining in the corners of the steel pipes must be removed manually using an electric pick or similar device.

[0006] Furthermore, in CFT columns, there are no gaps between the steel pipe and the concrete, so when gas cutting of the steel pipe is performed, the gas hits the concrete and is bounced back, which reduces cutting efficiency.In the method of Patent Document 1, in order to increase cutting efficiency, combustible materials or materials with voids are placed on the inner periphery of the steel pipe beforehand when manufacturing the CFT column, but manufacturing the CFT column is time-consuming.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a demolition method that can easily dismantle existing CFT columns. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention is a method for dismantling a concrete-filled steel pipe column in which concrete is filled inside the steel pipe, characterized by comprising: a step (a) of laying the concrete-filled steel pipe column, which has been removed from its installation location, on its side at a dismantling location; a step (b) of forming a core hole in the concrete inside the steel pipe through a hole formed in the steel pipe of the concrete-filled steel pipe column that has been laid on its side, and placing an explosive or non-explosive demolition agent in the core hole; and a step (c) of separating the steel pipe and the concrete using the explosive or non-explosive demolition agent.

[0009] In the present invention, when demolishing a concrete-filled steel pipe column, the concrete-filled steel pipe column is removed from its installation location and placed horizontally at the demolition location, and then the crushing force of explosives or non-explosive crushing agents placed in the concrete is used to break the bond between the steel pipe and the concrete, allowing the steel pipe and concrete to be efficiently separated, making it easier to separate the two and carry out the demolition work.

[0010] For example, the steel pipe has a polygonal cross section, and in step (b), a core hole is formed along a second surface of the steel pipe adjacent to the first surface from the hole formed in the first surface of the steel pipe of the concrete-filled steel pipe column placed horizontally, and in step (c), the second surface is separated from the concrete. In this way, by using explosives or non-explosive demolition materials provided in the core holes along the side of the steel pipe, it becomes easier to separate the side of the steel pipe from the concrete.

[0011] In the step (c), it is desirable to generate a crack between the second surface and the first surface, extending from the position of the hole in the axial direction of the concrete-filled steel pipe column. This allows the steel pipe to be separated from the concrete and at the same time the steel pipe can be split by the crack, making it easier to remove the steel pipe.

[0012] It is desirable that the multiple core holes are formed using different sides of the steel pipe as the first surfaces, and that all of the first surfaces are sides of the steel pipe other than the placement surface that is placed at the dismantling location. This allows the demolition work to proceed while the concrete-filled steel pipe column remains in place at the demolition site, improving work efficiency.

[0013] The multiple core holes may be formed using different side surfaces of the steel pipe as the first surface, and one of the side surfaces of the steel pipe, a placement surface, may be placed at the dismantling location, and the core holes may be formed using a side surface of the steel pipe other than the placement surface as the first surface.The steel pipe may then be rotated around its axis, and another placement surface of the side surface of the steel pipe, different from the placement surface, may be placed at the dismantling location, and the core holes may be formed using the original placement surface as the first surface. This will provide a wider range of demolition options compared to when demolition work is carried out while the CFT columns are still in place at the demolition site.

[0014] The steel pipe has a rectangular cross section, and for example, the core hole is formed in step (c) so that two sets of two side surfaces of the steel pipe that are continuous in an L shape, which are the second surfaces, are separated from the concrete. Alternatively, the core hole may be formed in step (c) so that four side surfaces of the steel pipe, which are the second surfaces, are separately separated from the concrete. In the former case, the steel pipe can be divided into two L-shaped steel pieces, which reduces the number of times the steel pieces need to be lifted using a crane, etc., making dismantling easier. In the latter case, the steel pipe can be divided into four plate-shaped steel pieces, which can be stacked and arranged to save space when transporting the steel pieces.

[0015] In the step (c), the steel pipe may be restrained from the outside, and the concrete may be pushed out toward the end of the steel pipe in the axial direction. In this case, the steel pipe and concrete of the concrete-filled steel pipe column can be easily separated by pushing out the concrete, making it easier to separate the two and carry out dismantling work.

[0016] After the step (c), it is desirable to crush and remove the concrete that has separated from the steel pipe. In the present invention, explosives and non-explosive demolition agents are used primarily for the purpose of separating the steel pipe from the concrete, not for the purpose of demolition of the concrete, and the concrete separated from the steel pipe is demolished and removed in a separate process. [Effects of the Invention]

[0017] According to the present invention, a demolition method can be provided that can easily dismantle existing CFT columns. [Brief explanation of the drawings]

[0018] [Figure 1] A diagram showing the state in which the CFT column 1 is laid down at the demolition location 2. [Figure 2] FIG. 2 is a diagram showing the state in which a hole 3 has been formed in a steel pipe 10. [Figure 3] FIG. 2 is a diagram showing the state in which a core hole 4 has been formed in concrete 20. [Figure 4] FIG. 2 is a diagram showing a state in which a detonating cord 5 is placed in a core hole 4. [Figure 5] A diagram showing the state after blasting of the detonating cord 5. [Figure 6] An example in which a steel pipe 10 is rotated to form a hole 3 and a core hole 4. [Figure 7] An example in which a steel pipe 10 is rotated to form a hole 3 and a core hole 4. [Figure 8] An example in which a steel pipe 10 is restrained by a restraining member 9. [Figure 9] A diagram showing the state after blasting of the detonating cord 5. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0020] [First embodiment] Figure 1 shows a CFT column 1 that has been lifted from its installation location by a crane or similar device, removed, and laid flat on a surface at a demolition location 2. In the demolition method according to an embodiment of the present invention, the target of demolition is not the free-standing CFT columns 1 that make up a building, but rather the CFT columns 1 that have been detached from their installation location within the building in advance by a separate means and then lifted by a crane or similar device.

[0021] The CFT column 1 is a column (concrete-filled steel pipe column) in which concrete 20 is filled inside a steel pipe 10. The cross section perpendicular to the axial direction of the CFT column 1 (hereinafter simply referred to as the cross section) is, for example, a square with sides of approximately 600 to 1,000 mm, and the total length of the removed CFT column 1 is approximately 3.5 to 4.0 m. However, the shape, dimensions, total length, etc. of the cross section of the CFT column 1 are not particularly limited. For example, the cross section of the CFT column 1 may be a rectangular shape other than a square, or may be a polygonal shape other than a rectangle.

[0022] In the dismantling method of the first embodiment, as shown in FIG. 2(a), first, a hole 3 is formed in the side surface of the steel pipe 10 of the CFT column 1 in a lying state.

[0023] Figure 2(b) is a diagram showing a cross section of the CFT column 1 at the position of line AA in Figure 2(a). In this embodiment, as shown in Figure 2(b), of the four side surfaces 101 to 104 of the steel pipe 10, a plurality of holes 3 (four in the example of Figure 2(b)) are formed on three different side surfaces 101 to 103, excluding side surface 104, which is the placement surface to be placed at the demolition site 2.

[0024] The holes 3 are formed at the corners of the cross section of the CFT column 1. In the example of Fig. 2(b), holes 3 are formed in one location near the top end of side surface 101, two locations near both the left and right ends of side surface 102, and one location near the bottom end of side surface 103. The hole 3 at the left end of side surface 102 is formed with its position in the axial direction of the CFT column 1 slightly shifted from the other holes 3.

[0025] These holes 3 are formed using a drilling tool such as a core drill, and their diameter is preferably about 30 to 50 mm. Furthermore, these holes 3 (and the core holes 4 described below) are formed with multiple cross sections spaced apart at intervals D in the axial direction of the CFT column 1, as shown in Figure 2(a). The interval D is, for example, about 1,000 mm to 1,500 mm, but the diameter of the holes 3 and the intervals D are not limited to these values.

[0026] Then, as shown in Figure 3(a), multiple core holes 4 are formed in the concrete 20 inside the steel pipe 10 through the holes 3 in the steel pipe 10. These core holes 4 are formed within the cross section of the CFT column 1, from the side surface (first surface) where the holes 3 are formed, along the side surface (second surface) adjacent to that side surface. The core holes 4 are formed so as to extend from the side surface where the holes 3 are formed to the vicinity of the side surface opposite that side surface (for example, up to about 50 mm before that side surface).

[0027] That is, a core hole 4 is formed along side surface 102 from hole 3 on side surface 101 to the vicinity of side surface 103, a core hole 4 is formed along side surfaces 101 and 103 from two holes 3 on side surface 102 to the vicinity of side surface 104, and a core hole 4 is formed along side surface 104 from hole 3 on side surface 103 to the vicinity of side surface 101.

[0028] Fig. 3(b) is a view of the side surface 101 of the steel pipe 10 as viewed from the outside. As shown in Fig. 3(b), the diameter of the core hole 4 is smaller than the diameter of the hole 3, and the core hole 4 is formed at a position closer to the side surface 102 within the hole 3. To form the core hole 4, for example, a core drill having a diameter one size smaller than that of the hole 3 can be used. The diameter of the core hole 4 is, for example, about 20 to 30 mm, but is not limited to this.

[0029] After forming the core holes 4, as shown in Figure 4, explosives such as detonating cord 5 are placed in the area from the back of core hole 4 to just before hole 3, and then wet sand or other filler material 6 is filled from the end of detonating cord 5 on the hole 3 side up into hole 3. Then, blasting of the detonating cords 5 in all core holes 4 of the CFT column 1 is carried out almost simultaneously. "All core holes 4" includes not only core holes 4 located within the same cross section of the CFT column 1, but also core holes 4 located within different cross sections.

[0030] When the detonating cord 5 is detonated, the impact of the blast creates gaps between the sides 101-104 of the steel pipe 10 and the concrete 20, as shown in Figure 5(a), and the sides 101-104 of the steel pipe 10 are separated from the concrete 20. The core hole 4 is formed so as to be in contact with the sides 101-104 of the steel pipe 10, which allows the impact of the blasting of the detonating cord 5 to be transmitted well to the steel pipe 10, making it easier to separate the steel pipe 10 and the concrete 20.

[0031] Furthermore, at the same time as the separation of the steel pipe 10 and the concrete 20, as shown in Figure 5(b), a crack 7 extending in the axial direction of the CFT column 1 from the position of the hole 3 (see Figure 2(a) etc.) occurs in the steel pipe 10. The crack 7 is formed between the side surface (first surface) where the hole 3 is formed and the side surface (second surface) adjacent to that side surface.

[0032] That is, the crack 7 is formed between the side surfaces 101 and 102 of the steel pipe 10, between the side surfaces 102 and 103, and between the side surfaces 103 and 104. As a result, the steel pipe 10 is roughly divided into an L-shaped continuous portion formed by the side surfaces 101 and 104, a plate-like portion formed by the side surface 102, and a plate-like portion formed by the side surface 103. In this embodiment, as shown in FIG. 2(b), the hole 3 at the upper end of the side surface 101 and the hole 3 at the left end of the side surface 102 are formed close to each other at the upper left corner of the cross section of the steel pipe 10. In such a case, the crack 7 is generated from one of the holes 3. In the example of FIGS. 5(a) and 5(b), the crack 7 is generated from the hole 3 at the upper end of the side surface 101.

[0033] When the divided steel pipes 10 are removed, the concrete 20 inside is actually found to be finely cracked at the outer periphery of the cross section, with a relatively large mass remaining in the center. The exposed concrete 20 is then crushed and removed using heavy machinery or the like.

[0034] As explained above, in this embodiment, when demolishing the CFT column 1, the CFT column 1 is removed from the installation location and placed lying down at the demolition location 2, and then the crushing force of the detonating cord 5 provided in the concrete 20 breaks the bond between the steel pipe 10 and the concrete 20, allowing the steel pipe 10 and the concrete 20 to be efficiently separated, facilitating the demolition work of separating the two. In particular, in this embodiment, the use of the detonating cord 5 provided along the side surfaces 101-104 of the steel pipe 10 makes it easier to separate the side surfaces 101-104 of the steel pipe 10 from the concrete 20.

[0035] Furthermore, in this embodiment, at the same time as the separation of the steel pipe 10 and the concrete 20, a crack 7 is generated in the steel pipe 10 in the axial direction of the CFT column 1, starting from the position of the hole 3, and the steel pipe 10 can be divided. This makes it easier to dismantle the steel pipe 10 and reduces dismantling costs. However, the generation of the crack 7 by blasting the detonating cord 5 is not essential, and the steel pipe 10 may be cut and removed by another method.

[0036] Furthermore, in this embodiment, the concrete 20 inside the steel pipe 10 can also be broken down to a certain size by the detonating cord 5, making it easier to remove the concrete 20. However, the detonating cord 5 is used primarily for the purpose of separating the steel pipe 10 from the concrete 20, not for the purpose of breaking up the concrete 20, and the concrete 20 separated from the steel pipe 10 must be broken up and removed using heavy machinery or the like in a separate process. Furthermore, because the detonating cord 5 is used primarily for the purpose of separating the steel pipe 10 from the concrete 20, a small amount of charge is required, which makes it possible to reduce noise and vibration, the generation of dust, and the scattering of debris during demolition.

[0037] Furthermore, in this embodiment, multiple holes 3 and core holes 4 (four in the example of Figure 3(a)) are formed in the cross section of the CFT column 1, and all of the core holes 4 are formed from the side surfaces 101 to 103 of the four side surfaces 101 to 104 of the steel pipe 10, excluding the side surface 104 which is the surface on which the CFT column 10 will be placed at the demolition location 2. In this embodiment, all of the holes 3 and core holes 4 can be formed by working on these side surfaces 101 to 103, so that the demolition work can be carried out while the CFT column 1 is left on the demolition location 2, improving work efficiency.

[0038] However, the present invention is not limited to the above embodiment. For example, in this embodiment, a detonation cord 5 is placed in the core hole 4 for blasting. However, the detonation cord 5 may be replaced with other explosives, such as water-containing explosives or amphoteric explosives, or non-explosive demolition agents. However, since water-containing explosives are gel-like explosives, they are suitable for densely packing the core hole 4. However, the charge amount depends on the diameter of the core hole 4, making it difficult to adjust the charge amount. Furthermore, non-explosive demolition agents are not classified as explosives under the Explosives Control Act and are therefore convenient to use and store. However, because they have lower blasting energy per unit amount than explosives, they require a larger charge amount, which increases costs, and the core hole 4 is larger in diameter, which increases construction time. Furthermore, because they are in powder form, they must be transferred to a separate container to adjust the charge amount.

[0039] In this embodiment, the detonating cords 5 in all of the core holes 4 of the CFT column 1 are detonated almost simultaneously, but the detonating cords 5 in the core holes 4 formed in different cross sections of the CFT column 1 may also be detonated at a predetermined time interval. However, detonating simultaneously allows for the blasting effect to be concentrated, thereby reducing the amount of charge required.

[0040] Furthermore, in this embodiment, four core holes 4 are formed in the cross section of the CFT column 1, but the number of core holes 4 in the cross section is not limited to this. For example, of the four core holes 4 in Figure 3(a), the core hole 4 along the side surface 104 of the steel pipe 10 may be omitted. In this case, however, adhesion between the side surface 104 and the concrete 20 remains, which makes the work of removing the steel pipe 10 and the concrete 20 time-consuming.

[0041] Furthermore, the hole 3 may be formed in the steel pipe 10 by gas cutting instead of using a drilling tool. However, if gas cutting is attempted when there is no gap between the concrete 20 and the steel pipe 10, the gas jet will be bounced off the concrete 20, reducing cutting efficiency, so it is more efficient to use a drilling tool.

[0042] Furthermore, the spacing D between the holes 3 in the axial direction of the CFT column 1 is adjusted according to the required fracture level of the steel pipe 10. Although this varies depending on the cross-sectional area of ​​the CFT column 1 and the compressive strength of the concrete 20, if the spacing D is appropriate, cracks 7 will form connecting multiple holes 3 in the axial direction of the CFT column 1, allowing brittle fracture (cracks 7) to occur continuously in the axial direction of the CFT column 1 at the corners of the steel pipe 10. If the spacing D is wider than this, the separation between the steel pipe 10 and the concrete 20 will be complete internally, but the brittle fracture of the steel pipe 10 will be partial, and additional cutting work will be required to remove the steel pipe 10.

[0043] As shown in Figure 6(a), with the side 104 (placement surface) of the steel pipe 10 placed on the demolition area 2, core holes 4 are formed from holes 3 made in three different side surfaces 101, 102, 103 (first surfaces) of the steel pipe 10 along the side surfaces 102, 101, 104 (second side surfaces) adjacent to each of the side surfaces 101, 102, 103, and a detonating cord 5, etc. is then placed.Then, as shown in Figure 6(b), the steel pipe 10 is rotated around its axis so that a different side surface 103 (placement surface) different from the side surface 104 previously placed on the demolition area 2 is placed on the demolition area 2, and a core hole 4 is formed from the hole 3 made in the original placement surface, side surface 104 (first surface), along the side surface 103 (second surface) adjacent to the side surface 104, and a detonating cord 5, etc. is placed.

[0044] When the detonation cords 5 in these core holes 4 are detonated almost simultaneously, as shown in Figure 6(c), the sides 101-104 of the steel pipe 10 are separated from the concrete 20, and these sides 101-104 are roughly divided by a crack 7 into two sets of consecutive L-shaped sides, namely, the set of sides 101 and 104 and the set of sides 102 and 103. In this example, as shown in Figure 6(b), the hole 3 at the bottom end of side 104 and the hole 3 at the left end of side 103 are formed close to each other at the lower left corner of the cross section of the steel pipe 10, and as before, the crack 7 originates from one of the holes 3 (in this example, the hole 3 at the left end of side 103). Similarly, at the upper right corner of the cross section of the steel pipe 10, the hole 3 at the top end of the side surface 102 and the hole 3 at the right end of the side surface 101 are formed close to each other as shown in Figure 6(b), and the crack 7 originates from one of the holes 3 (in this example, the hole 3 at the right end of the side surface 101).

[0045] As shown in Figure 7(a), with the side 104 (placement surface) of the steel pipe 10 placed on the demolition area 2, core holes 4 are formed from holes 3 made in three different side surfaces 101, 102, 103 (first surfaces) of the steel pipe 10 along the 102, 103, 104 (second surfaces) adjacent to each of the side surfaces 101, 102, 103, and detonating cord 5, etc. are arranged, and then, as shown in Figure 7(b), the steel pipe 10 is rotated around its axis so that the side surface 103 (placement surface) different from the side surface 104 previously placed on the demolition area 2 is placed on the demolition area 2, and a core hole 4 is formed from the hole 3 made in the original placement surface, side surface 104 (first surface), along the side surface 101 (second surface) adjacent to the side surface 104, and detonating cord 5, etc. are arranged.

[0046] When the detonating cords 5 in these core holes 4 are detonated almost simultaneously, the sides 101 to 104 of the steel pipe 10 separate from the concrete 20, and these sides 101 to 104 are divided into separate plate-like members by cracks 7, as shown in Figure 7(c).

[0047] As shown in Figures 6 and 7, forming holes 3 and core holes 4 while rotating the steel pipe 10 around its axis provides a wider range of demolition options, including the shape of the steel pipe 10, compared to when the CFT column 1 is left in place at the demolition site 2. For example, when the sides 101-104 of the steel pipe 10 are divided into two L-shaped steel pieces as shown in Figure 6, the number of times the steel pieces need to be lifted using a crane or other device is reduced to two, making the demolition easier. Furthermore, using the L-shaped steel pieces as slides makes it easier to consolidate concrete blocks. In the example shown in Figure 7, the sides 101-104 of the steel pipe 10 are divided into four plate-shaped steel pieces, which can be stacked to save space during transportation.

[0048] Next, another example of separating steel pipe 10 and concrete 20 by blasting detonating cord 5 will be described as a second embodiment. The second embodiment will be mainly described with respect to differences from the first embodiment, and similar features will be denoted by the same reference numerals in the drawings and the like and will not be described again. Furthermore, the configuration described in the first embodiment can be used in combination with the configuration described in the second embodiment as necessary.

[0049] [Second embodiment] In the second embodiment, the steel pipe 10 and the concrete 20 are separated by blasting the detonating cord 5 to push the concrete 20 toward the axial end of the CFT column 1. In this embodiment, when separating the steel pipe 10 and the concrete 20, it is not necessary to divide the steel pipe 10 as in the first embodiment.

[0050] In this embodiment, as shown in Figure 8(a), the CFT column 1 is placed lying down at the demolition site 2 via sleepers 21. Figure 8(a) is a view of the side of the CFT column 1 seen from the outside, and a diaphragm 8 is also provided inside the steel pipe 10.

[0051] Figure 8(b) is a diagram showing a cross section of the CFT column 1 taken along line BB in Figure 8(a). In the cross section of the CFT column 1, multiple holes 3 and core holes 4 are formed, as in the first embodiment, and detonating cords 5 and filler materials 6 are provided in these holes 3 and core holes 4.

[0052] In this embodiment, a plurality of holes 3 are formed in the side surface 104, which is the mounting surface of the steel pipe 10, and the core hole 4 is formed so as to extend from the side surface 104 on which the holes 3 are formed to the vicinity of the side surface 102 opposite to the side surface 104. The core hole 4 is not formed along the side surfaces 101, 103 of the steel pipe 10 as in the first embodiment, but is provided at a distance from the side surfaces 101, 103. However, it is possible to provide the core hole 4 along the side surfaces 101, 103 of the steel pipe 10.

[0053] In this embodiment, a restraining member 9 that restrains the steel pipe 10 from the outside is also attached to the CFT column 1. The restraining member 9 connects corresponding ends of horizontal steel members 91 arranged above and below the steel pipe 10 with connecting members 92 such as steel rods on the sides of the steel pipe 10. The upper and lower ends of the connecting members 92 penetrate the upper and lower steel members 91 of the steel pipe 10 and protrude from the steel members 91. Threads are provided at the upper and lower ends of the connecting members 92, and the upper and lower steel members 91 of the steel pipe 10 are connected by the connecting members 92 by tightening nuts 93 onto the protruding parts of the ends from the steel members 91. The restraining member 9 is provided so that the upper and lower steel members 91 restrain the steel pipe 10 from the outside with the upper and lower steel members 91 and so that the lower steel member 91 externally closes the hole 3 formed in the steel pipe 10. Note that, for example, H-shaped steel is used as the steel members 91, but this is not limited thereto. The connecting members 92 are also not limited to steel rods.

[0054] In addition, in this embodiment, the cross section of the CFT column 1 forming the hole 3 and the core hole 4 (cross section taken along line BB in Figure 8(a)) is located closer to the base of the CFT column 1 in the axial direction than the diaphragm 8 (the lower end side when installed within a building).

[0055] In this state, when the detonation cord 5 is detonated in the same manner as in the first embodiment, as shown in Figure 9, the concrete 20 inside the steel pipe 10 is divided at the cross section, and the concrete 20 located at the base of the CFT column 1 is pushed out toward the end of the base of the CFT column 1, i.e., the end on the free face side, as shown by arrow C, and separated from the side surfaces 101-104 of the steel pipe 10. The pushed-out concrete 20 and the steel pipe 10 are then removed separately. The concrete 20 can be crushed using heavy machinery or the like.

[0056] In the second embodiment, by restraining the outside of the steel pipe 10 with the restraining member 9, the expansion of the steel pipe 10 when the detonation cord 5 is detonated is suppressed, and the concrete 20 is pushed out of the steel pipe 10 by the energy when the detonation cord 5 is detonated. This makes it easy to separate the steel pipe 10 from the concrete 20 inside, facilitating the demolition work of separating the two.

[0057] In the second embodiment, by blocking the hole 3 with the restraining member 9, it is possible to confine the blasting effect within the steel pipe 10 without letting the gas generated during blasting escape, and it becomes possible to separate the concrete 20 from the steel pipe 10 with a smaller amount of powder. In addition, scattering of the filling material 6 and the like is prevented, making blasting safer.

[0058] The shape and configuration of the restraining member 9 can be variously considered and are not particularly limited. The restraining member 9 may restrain the left and right side surfaces of the steel pipe 10 from the outside, or may restrain all of the side surfaces from the outside. In this embodiment, the restraining member 9 is arranged so as to block all of the holes 3 of the steel pipe 10 from the outside, but it may also block only some of the holes 3 from the outside, and in some cases, the restraining member 9 may not be arranged to block the holes 3.

[0059] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications or alterations within the scope of the technical ideas disclosed herein, and it is understood that these modifications also fall within the technical scope of the present invention. [Explanation of symbols]

[0060] 1:CFT pillar 2: Dismantling area 3: Hole 4: Core hole 5: Detonating wire 6: Inclusions 7: Crack 8: Diaphragm 9: Restraining member 10: Steel pipe 20: Concrete 101~104: Side

Claims

1. A method for dismantling a concrete-filled steel pipe column in which concrete is filled in the steel pipe, Step (a) of laying the concrete-filled steel pipe column removed from the installation location at a demolition location; A step (b) of forming a core hole in the concrete inside the steel pipe from the hole formed in the steel pipe of the concrete-filled steel pipe column placed horizontally, and placing explosives or non-explosive demolition agents in the core hole; (c) a step of separating the steel pipe and the concrete using the explosives or non-explosive demolition agent; A dismantling method comprising:

2. The steel pipe has a polygonal cross section, In the step (b), the core hole is formed along a second surface adjacent to the first surface of the steel pipe from the hole formed in the first surface of the steel pipe of the concrete-filled steel pipe column placed horizontally, 2. The demolition method according to claim 1, wherein in step (c), the second surface is separated from the concrete.

3. A demolition method as described in claim 2, characterized in that in step (c), a crack is generated between the second surface and the first surface, extending from the position of the hole in the axial direction of the concrete-filled steel pipe column.

4. A plurality of the core holes are formed with different side surfaces of the steel pipe as the first surface, 3. The dismantling method according to claim 2, wherein all of the first surfaces are side surfaces of the steel pipe other than the placement surface placed at the dismantling location.

5. A plurality of the core holes are formed with different side surfaces of the steel pipe as the first surface, In a state where a placement surface, which is one of the side surfaces of the steel pipe, is placed on the dismantling location, the core hole is formed with the side surface of the steel pipe other than the placement surface as the first surface, and then The dismantling method according to claim 2, characterized in that the steel pipe is rotated around an axis, and another loading surface of the side of the steel pipe different from the loading surface is placed on the dismantling location, and the core hole is formed with the original loading surface as the first surface.

6. The steel pipe has a rectangular cross section, The demolition method according to claim 3, characterized in that in step (c), the core holes are formed so that two sets of the two side surfaces of the steel pipe that are continuous in an L-shape, which are the second surfaces, are separated from the concrete.

7. The steel pipe has a rectangular cross section, 4. The demolition method according to claim 3, wherein in step (c), the core hole is formed so that the four sides of the steel pipe, which are the second surface, are separately separated from the concrete.

8. 2. The demolition method according to claim 1, wherein in step (c), the steel pipe is restrained from the outside and the concrete is pushed out toward the axial end of the steel pipe.

9. 2. The demolition method according to claim 1, wherein after step (c), the concrete separated from the steel pipe is crushed and removed.

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