Construction method of permanent sub-structural column

Abstract

To improve workability when constructing a permanent sub-structural column using a steel pipe with a bottom cap in an inverted construction method.SOLUTION: A construction method of a permanent sub-structural column used in an inverted construction method comprises: a steel pipe insertion process in which a steel pipe with a bottom cap in an upright position is inserted into a ground hole excavated while supplying a stabilizing liquid; a weight installation process in which a weight is lowered into a hollow part of the steel pipe with a bottom cap and supported by the steel pipe with a bottom cap; a pouring process in which a cement-based solidification material is poured into the ground hole to a depth at which a lower part of the steel pipe with a bottom cap is embedded; and a weight removal process in which, after the cement-based solidification material is hardened, the weight is hoisted and removed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for constructing a structural column used in an inverted construction method. [Background technology]

[0002] As underground spaces continue to grow in size, the inverted construction method is often used for the construction of structures in order to shorten the construction period and to be considerate of the surrounding environment. The inverted construction method is a construction method in which the underground framework is constructed from upper floors to lower floors by repeatedly excavating the ground and constructing the framework while using the floor beams of the building body as bracing. Before starting excavation of the ground, structural columns used to support the floor beams are installed underground.

[0003] As the structural columns, steel columns and columns of concrete-filled steel pipe structure are used, and for example, Patent Document 1 discloses a structural column of concrete-filled steel pipe structure and a method for constructing the same. Specifically, a steel pipe with a bottom lid is erected in a pile hole that is excavated and constructed while being filled with a stabilizing liquid, while fresh water is poured into the hollow part.

[0004] Next, concrete is poured into the pile hole to construct a cast-in-place pile, and the bottom end of the steel pipe is joined to the cast-in-place concrete pile. After this, the fresh water inside the steel pipe is drained and replaced with concrete to construct a concrete-filled steel pipe structural column underground. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-54164 A Summary of the Invention [Problem to be solved by the invention]

[0006] According to Patent Document 1, when erecting a steel pipe in a pile hole, if ballast water such as fresh water is injected into the hollow part, the effect of buoyancy on the steel pipe from the stabilizing liquid and fresh concrete can be offset, and the steel pipe can be erected with high accuracy. However, the use of ballast water not only has the risk of causing rust on the steel pipe, but also necessitates the insertion of a small submersible pump into the steel pipe in the upright position and the discharge operation.

[0007] It is assumed that small submersible pumps do not have sufficient discharge capacity to pump the fresh water they suck in to the top of the steel pipe and then discharge it. In such cases, the equipment used for drainage tends to become complicated, such as discharging water by arranging multiple pumps and lifting pipes in series, and the work becomes complicated.

[0008] The present invention has been made in consideration of the above problems, and its main object is to improve workability when constructing structural columns using steel pipes with bottom caps in the inverted construction method. [Means for solving the problem]

[0009] In order to achieve this object, the method for constructing a structural column of the present invention is a method for constructing a structural column used in a reverse construction method, and is characterized by comprising a steel pipe insertion step of inserting a steel pipe with a bottom cap in an upright position into a dug underground hole while supplying a stabilizing liquid, a weight installation step of suspending a weight into the hollow portion of the steel pipe with a bottom cap and supporting the weight on the steel pipe with a bottom cap, a pouring step of pouring a cement-based solidification material into the underground hole to a depth at which the lower part of the steel pipe with a bottom cap will be buried, and a weight removal step of hoisting and removing the weight after the cement-based solidification material has hardened.

[0010] The method for constructing a structural column of the present invention is characterized in that the weight installation process is carried out in the middle of the steel pipe insertion process.

[0011] The method for constructing a structural column of the present invention is characterized in that the weight installation process is carried out after the steel pipe insertion process and before the casting process.

[0012] The method for constructing a structural column of the present invention is characterized in that the steel pipe with a bottom cap comprises a steel pipe body formed by connecting a plurality of pipe materials in the axial direction and a bottom cap that covers the lower end of the steel pipe body, and in the steel pipe insertion process, the pipe materials are sequentially added to extend the steel pipe with a bottom cap.

[0013] The method for constructing a structural column of the present invention is characterized in that the hanging material for suspending the weight is made by connecting a plurality of hanging material bodies, and in the weight installation process, the hanging material bodies are sequentially added to extend the hanging material.

[0014] The method for constructing a structural column of the present invention is characterized in that a guide frame for the weight is provided on the upper surface of the bottom cover of the steel pipe with a bottom cover, and in the weight installation process, the weight suspended inside the guide frame is stored.

[0015] According to the method for constructing a structural column of the present invention, a weight is placed on the steel pipe with a bottom cap inserted in an underground hole in an upright position. This makes it possible to offset the buoyancy caused by the stabilizing liquid or the unhardened concrete poured in the underground hole, which acts on the steel pipe with a bottom cap inserted in the underground hole, with the weight. Therefore, it becomes possible to erect the steel pipe with a bottom cap in an upright position in the underground hole in a stable state.

[0016] In addition, the steel pipe insertion process can be performed at any stage before buoyancy is generated, such as during the steel pipe insertion process, or after the steel pipe insertion process and before the casting process, or before the steel pipe insertion process. Furthermore, the weight can be easily removed by pulling it out from the top end of the steel pipe with the bottom cap using a hanging material. Therefore, it is possible to omit the troublesome work of preparing an underwater pump and performing drainage work, as in the case of using ballast water as a buoyancy countermeasure as in the conventional technology, and this contributes to shortening the construction period. In addition, the removed weight can be reused, which is economical.

[0017] In addition, since the weight is placed in the hollow part of the steel pipe body, it does not affect the shape of the outer surface of the structural column. Therefore, for example, even when constructing a structural column using a steel pipe with a bottom cap and a diaphragm or the like attached to the outer surface, the weight can be used to efficiently carry out the work. Effect of the Invention

[0018] According to the present invention, by placing a weight in the hollow portion of a steel pipe with a bottom cap, it is possible to improve workability when constructing a structural column using a steel pipe with a bottom cap in the inverted construction method. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing a method for constructing a structural column in an embodiment of the present invention (part 1). [Diagram 2] FIG. 2 is a diagram showing a method for constructing a structural column in an embodiment of the present invention (part 2). [Diagram 3] FIG. 3 is a diagram showing a method for constructing a structural column in an embodiment of the present invention (part 3). [Figure 4] FIG. 2 is a diagram showing a steel pipe with a bottom cap and a weight in an embodiment of the present invention. [Diagram 5] FIG. 13 is a diagram showing another example of a method for constructing a structural column in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention is a method suitable for constructing a structural column of concrete-filled steel pipe construction (hereinafter referred to as CFT construction) among structural columns used in the inverted construction method. The structural column construction method will be described in detail below with reference to Figs. 1 to 5.

[0021] ≪≪Main pillar≫≫ A CFT structural column 100 is used in an inverted construction method, which is one of the methods for constructing the underground skeleton of a building or an underground structure, and is constructed using an underground hole H, as shown in Figures 1 to 3. As shown in Figure 3(c), the structure includes a steel pipe 10 with a bottom cap and concrete C2 poured into the hollow part of the steel pipe 10 with a bottom cap, and a steel material 32 is suspended from the lower end of the steel pipe 10 with a bottom cap.

[0022] <Steel pipe with bottom cap> As shown in Fig. 4(a), the steel pipe with bottom cap 10 comprises a steel pipe body 20 and a bottom cap 30. The steel pipe body 20 is constructed by connecting pipe members 21 made of round steel pipes or square steel pipes in an axial direction.

[0023] The bottom cover 30 is made of, for example, a steel plate and is provided so as to close the lower end of the steel pipe body 20 arranged in an upright position. The steel material 32 is provided on the underside of the bottom cover 30.

[0024] The steel material 32 is a so-called cross H-shaped steel material, which is made by combining H-shaped steel in a cross shape to form a horizontal cross section. However, the steel material 32 is not limited to this, and any material that is generally used for the structural column 100 may be used for the steel material 32.

[0025] ≪≪How to construct a structural pillar≫≫ The structural column 100 having the above-mentioned configuration can be constructed by using the weight 40 to which the hanging member 50 is attached, for example, by the method shown in Figs.

[0026] ≪Preparation process≫ As shown in Fig. 1(a), at a planned construction position of a structural column 100, an underground hole H is drilled while supplying a stabilizing solution W. Next, a reinforcing bar cage 70 is placed in the underground hole H filled with the stabilizing solution W.

[0027] <Steel pipe insertion process> Thereafter, as shown in Figs. 1(b) to (c) and Fig. 2(a), the steel pipe 10 with a bottom cap is inserted and erected into the underground hole H while adding pipe material 21.

[0028] Specifically, a bottom cover 30 is installed at the lower end of a pipe material 21, and a steel material 32 is suspended from this bottom cover 30 to prepare a steel pipe 10 with a bottom cover. This is then hung down into an underground hole H, as shown in FIG. 1(b).

[0029] ≪Weight installation process≫ As shown in Fig. 1(c) , a weight 40 is inserted into the hollow part of the steel pipe with bottom cap 10 inserted into the underground hole H. The weight 40 is hung down using a hanging member 50 and landed on the upper surface of the bottom cap 30. In this way, the weight 40 is supported by the steel pipe with bottom cap 10. At this time, the hanging member 50 attached to the weight 40 is held by, for example, a bar bar 60 installed on the pipe material 21.

[0030] <Continuation of steel pipe insertion process> The steel pipe 10 with bottom cap inserted into the underground hole H is connected by adding pipe members 21 until it reaches the desired total length. At the same time, the hanging member body 51 is connected to the hanging member 50 to extend it.

[0031] Specifically, as shown in Fig. 2(a), the pipe material 21 to be extended is hung directly above the underground hole H, and the hanging material body 51 to be extended to the hanging material 50 is attached to the hollow portion of the pipe material 21 by penetrating it. Then, this hanging material body 51 is connected to the hanging material 50 held by the bar 60 via a connecting member 52. Any connecting member 52 may be used as long as it has a joint structure that allows the hanging material body 51 to be connected.

[0032] When the hanging material 50 is extended by the hanging material body 51, the bar 60 is removed. After this, the pipe material 21 to be extended is connected to the upper end of the steel pipe 10 with bottom cap inserted into the underground hole H, and the steel pipe 10 with bottom cap is inserted into the underground hole H by the length of the extension.

[0033] The work of joining the pipe material 21 to the steel pipe 10 with a bottom cap and the work of joining the hanging material body 51 to the hanging material 50 are carried out in parallel. In this way, when the work of joining the pipe material 21 to the steel pipe 10 with a bottom cap is carried out, the work of joining the pipe material 21 can be carried out quickly without interference from the hanging material 50.

[0034] Furthermore, while the underground hole H is filled with the stabilizing liquid W, a weight 40 has already been placed in the hollow part of the steel pipe 10 with a bottom cap. Therefore, during the intermediate stage of extending and inserting the steel pipe 10 with a bottom cap into the underground hole H, it is possible to avoid situations in which the upright posture becomes unstable due to the influence of buoyancy, or the steel pipe 10 becomes stuck at a high position, and the steel pipe 10 with a bottom cap can be smoothly inserted into the underground hole H.

[0035] <Pouring process> After the steel pipe 10 with a bottom cap is erected at a predetermined depth, a tremie pipe (not shown) is placed between the steel pipe 10 with a bottom cap and the underground hole H. Using this tremie pipe, concrete C1 is poured up to a predetermined height in the underground hole H, and the reinforcing bar cage 70, the steel material 32, and a part of the lower part of the steel pipe 10 with a bottom cap are buried as shown in Fig. 2(b).

[0036] When part of the stabilizing liquid W filling the underground hole H is replaced with concrete C1, the buoyancy acting on the steel pipe with bottom cap 10 increases. Therefore, when designing the weight 40, it is advisable to set the weight taking into consideration the change in the buoyancy acting on the steel pipe with bottom cap 10 during the casting process.

[0037] ≪Weight removal process≫ Once the concrete C1 has hardened and the cast-in-place pile P has been constructed in the underground hole H, the weight 40 in the hollow portion of the steel pipe 10 with bottom cap is removed.

[0038] For example, as shown in Fig. 3(a), the gap between the underground hole H and the steel pipe 10 with a bottom cap is backfilled with a backfilling material 80. Next, as shown in Fig. 3(b), the weight 40 is lifted from the upper end of the steel pipe 10 with a hanging material 50 and removed. Note that the work of removing the weight 40 may be performed simultaneously with or before the backfilling work with the backfilling material 80, as long as it is performed after the concrete C1 has hardened.

[0039] ≪Filling process≫ After removing the weight 40, the bottom-capped steel pipe 10 is filled with concrete C2 as shown in Fig. 3(c), thereby completing the construction of the CFT structural column 1.

[0040] According to the above-mentioned method for constructing a structural column, the steel pipe 10 with a bottom cap in an upright position inserted into the underground hole H is supported by the weight 40, so that even if buoyancy caused by the stabilizing liquid W or the unhardened concrete C1 poured into the underground hole H acts on the steel pipe 10 with a bottom cap, this buoyancy can be offset by the weight 40. Therefore, it is possible to maintain the steel pipe 10 with a bottom cap in an upright position in the underground hole H in a stable state and erect it in the underground hole H.

[0041] In addition, the weight 40 can be easily removed by pulling it out from the top end of the steel pipe 10 with the bottom cap by using the hanging material 50. This eliminates the need for a submersible pump to perform the drainage work, as in the case of using ballast water as a buoyancy countermeasure in the conventional technology, and contributes to shortening the construction period. Furthermore, the removed weight 40 can be reused when constructing multiple structural columns 100 at the same site, which also improves the cost efficiency.

[0042] Furthermore, since the weight 40 is provided in the hollow portion of the steel pipe 10 with a bottom cap, there is no effect on the shape of the outer circumferential surface of the structural column 100. Therefore, for example, even when using a steel pipe 10 with a bottom cap having a diaphragm or the like attached to its outer circumferential surface, the method of constructing the structural column 100 using the weight 40 can be applied.

[0043] ≪≪Weight≫≫ As described above, the weight of the weight 40 used in the method for constructing the structural column 100 is appropriately adjusted according to the buoyant force acting on the steel pipe with bottom cap 10. The material of the weight 40 may be any of concrete, steel, castings, etc., and the external shape is not limited in any way.

[0044] 4(a) shows an example in which the weight 40 is manufactured into a columnar body. However, as long as the weight 40 can be stably installed inside the steel pipe body 20, it may be in the form of, for example, a cone or multiple stacked pieces.

[0045] In addition, when the weight 40 is manufactured into a columnar shape, for example, if the diameter of the steel pipe body 20 is about 1,500 mm, the diameter of the cross section in plan view of the weight 40 is set to 1 mm when the weight 40 is a round column. 2 In the case where the weight 40 is a rectangular column, the length of one side of the cross section in plan view is set to about 1 m. Then, the weight can be adjusted by changing the height.

[0046] There is no limitation on the height position at which such a weight 40 is provided in the hollow portion of the bottom-capped steel pipe 10. As shown in Fig. 4(a), it may be provided on the top surface of the bottom cap 30, or as shown in Fig. 4(c), it may be provided at the middle height of the hollow portion.

[0047] When placing the weight 40 on the top surface of the bottom cover 30, for example, as shown in Fig. 4(b), a guide frame 31 that also serves to prevent slippage may be placed on the top surface of the bottom cover 30, and the guide frame 31 may guide the placement position of the weight 40. If this guide frame 31 is placed so as to surround the central axis of the steel pipe 10 with bottom cover, the weight 40 can be smoothly guided and stored / placed on this central axis.

[0048] On the other hand, when the weight 40 is installed at the middle height of the steel pipe with bottom cap 10, for example, as shown in Fig. 4(c), a support frame 22 may be provided on the inner peripheral surface of the pipe material 21, and the weight 40 may be supported by this. When the support frame 22 is provided on the pipe material 21, it is preferable to use a structure that can maintain the hollow part of the steel pipe with bottom cap 10 in a connected state without dividing it. This is in consideration of the fact that concrete C2 will be poured into the hollow part of the steel pipe with bottom cap 10 after the weight 40 is removed using the hanging material 50, as explained with reference to Fig. 3(c).

[0049] <<Hanging material>> In addition, in this embodiment, the hanging material 50 used to suspend or lift and remove the weight 40 is, as shown in Figure 4(a), an example in which it is composed of a short, rod-shaped hanging material main body 51 and a connecting member 52 such as a joint that connects these hanging material main bodies 51 together.

[0050] However, the suspending material body 51 is not limited in any way and may be made of a cord-like body such as a wire or cable material. Also, for example, when a wire is used for the suspending material body 51, if the suspending material body 51 can be connected without using the connecting member 52, the connecting member 52 may be omitted.

[0051] The method of erecting structural columns of the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0052] In this embodiment, a method is given as an example in which the steel pipe insertion process involves extending the steel pipe 10 with a bottom cap while adding pipe material 21, and inserting it into the underground hole H. In this way, a long structural column 100 can be constructed even at a site with a low headroom. However, at a site with no height restrictions, the steel pipe 10 with a bottom cap may be manufactured to the required length in advance, and inserted and erected into the underground hole H without performing the work of adding more pipe material.

[0053] <Other examples of weight installation processes> In this embodiment, a weight installation process is carried out in which the weight 40 is hung down and supported by the steel pipe 10 with a bottom cap at an intermediate stage in which the steel pipe 10 with a bottom cap is being extended and inserted into the underground hole H. However, the weight 40 may be installed in the hollow portion on the ground beforehand, before the steel pipe 10 with a bottom cap is inserted into the underground hole H.

[0054] Alternatively, after inserting the steel pipe 10 with a bottom cap into the underground hole H, the weight 40 may be supported by the steel pipe 10 with a bottom cap until the concrete C1 is poured into the underground hole H. This is effective when it has been confirmed in advance that the steel pipe 10 with a bottom cap is heavy and can maintain a stable upright position in the stabilizing liquid W, but will become unstable due to the action of buoyancy during the process of pouring the concrete C1.

[0055] That is, as shown in Fig. 5(a), a bottom cover 30 is installed at the lower end of a pipe material 21, and a steel pipe 10 with a bottom cover is prepared in which a steel material 32 hangs down from the bottom cover 30, and this is then hung down into an underground hole H. Next, as shown in Fig. 5(b), pipe materials 21 are added and connected until the steel pipe 10 with a bottom cover reaches the desired total length.

[0056] When the steel pipe with bottom cap 10 reaches the desired length, as shown in Fig. 5(c), before carrying out the step of pouring concrete C1, the steel pipe with bottom cap 10 is hung down into the hollow part thereof using a hanging member 50 and placed on the bottom cap 30. In this case, the hanging member 50 attached to the weight 40 does not interfere with the operation of joining the pipe material 21 to the steel pipe with bottom cap 10. Therefore, it is not necessary to adopt a configuration in which multiple hanging member bodies 51 are connected to the hanging member 50 as shown in Fig. 4(a). [Explanation of symbols]

[0057] 100 Structure pillar 10 Steel pipe with bottom cap 20 Steel pipe body 21 Piping material 22 Support Frame 30 Bottom lid 31 Information Frame 32 Steel materials 40 Weight 50 Hanging material 51 Hanging material body 52 Connecting member 60 Hairpin Muscle 70 Reinforced Concrete Cage H underground hole P Cast-in-place pile C1 Concrete (cement-based solidification material) C2 Concrete W Stabilizing Solution

Claims

1. A method for constructing a structural column for use in an inverted construction method, comprising the steps of: a steel pipe insertion process for inserting the steel pipe with the bottom cap in an upright position into the excavated underground hole while supplying a stabilizing liquid; a weight installation process in which a weight is lowered into the hollow portion of the steel pipe with a bottom cap and the weight is supported by the steel pipe with a bottom cap; A casting process of casting a cement-based solidification material into the underground hole to a depth at which the lower part of the bottom-capped steel pipe is buried; a weight removal process of lifting and removing the weight after the cement-based solidification material has hardened; A method for constructing a structural column, comprising:

2. The method for constructing a structural column according to claim 1, A method for constructing a structural column, characterized in that the weight installation process is carried out in the middle of the steel pipe insertion process.

3. The method for constructing a structural column according to claim 1, A method for constructing a structural column, characterized in that the weight installation process is carried out after the steel pipe insertion process and before the casting process.

4. The method for constructing a structural column according to claim 1, The steel pipe with a bottom cap comprises a steel pipe body formed by connecting a plurality of pipe materials in the axial direction, and a bottom cap that closes the lower end of the steel pipe body, A method for constructing a structural column, characterized in that in the steel pipe insertion process, the pipe material is sequentially added to extend the steel pipe with a bottom cap.

5. A method for constructing a structural column according to claim 1, The hanging member for hanging the weight is formed by connecting a plurality of hanging member bodies, A method for constructing a structural column, characterized in that in the weight installation process, the hanging material body is sequentially added to extend the hanging material.

6. A method for constructing a structural column according to claim 1, A guide frame for the weight is provided on an upper surface of the bottom cover of the bottom cover-equipped steel pipe, A method for constructing a structural column, characterized in that in the weight installation process, the weight suspended inside the guide frame is stored.

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