Caisson construction method and construction auxiliary device

Abstract

To provide a caisson construction method and construction auxiliary device that can improve workability of constructing a caisson on a small plane.SOLUTION: A caisson skeleton construction method comprises the steps of: installing an embedded formwork 12 in a wall-like manner at one side in a thickness direction of a planned concrete pouring area A of the skeleton; attaching an overhanging member 16 to an engaging portion 14 provided on a side surface 20 of the embedded formwork 12 facing the planned concrete pouring area A; arranging reinforcing bars in the planned concrete pouring area A using a scaffolding board 18 provided on the overhanging member 16 attached to the engaging portion 14 as a scaffold; and removing the overhanging member 16 from the engaging portion 14 after arranging the reinforcing bars and before pouring concrete in the planned concrete pouring area A.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a construction method and construction auxiliary device for caissons used, for example, in bridge foundations, vertical shafts, etc. [Background technology]

[0002] Traditionally, the pneumatic caisson method has been widely adopted as a construction method for bridge foundations and vertical shafts, but the "slim caisson method" is used for constructing caissons in narrow areas, which are intended for caissons with small flat areas (see, for example, Patent Document 1). As shown in Figure 3, in the normal pneumatic caisson method, Material Lock LF1 (lifting equipment for the earth removal bucket) and Man Lock LF2 (lifting equipment for workers) are installed separately inside the body 1, but in the slim caisson method, by using the specially manufactured shaft LF3 for slim caissons (equipment that combines Material Lock and Man Lock into one), it is possible to construct small flat and circular caissons with a diameter of 7.0 m or less. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-154517 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the conventional slim caissons mentioned above have the characteristic that they must ensure the high performance requirements of structures such as bridge foundations and shafts with a small cross section, the amount of reinforcing bars per unit volume of the body 1 (2 outer main bars, 3 inner main bars, 4 distribution bars, 5 shear reinforcement bars) tends to be very large in design, as shown in the example in Figure 4.

[0005] Furthermore, the construction of slim caissons with these characteristics poses the following construction problems (1) to (3). (1) Workability of rebar assembly scaffolding When assembling high-density reinforcement as in the example of Figure 4, it is necessary to temporarily set up a rebar assembly scaffold 6 with a frame structure that is closed all the way around inside the main body 1, as shown in Figure 5. However, since the width W of the work floor 7 can only be secured at a maximum of about 240 mm and the interior is narrow, there is a risk that workability and safety will be reduced.

[0006] (2) Construction loss due to interference with temporary caisson equipment As shown in Figure 6, inside the skeleton 1, temporary equipment specific to the caisson method is installed vertically, avoiding the rebar assembly scaffolding 6 and the structural rebars 2 to 5. These include an air supply pipe P1 (outer diameter approximately 200 mm) that sends compressed air from the ground to the work chamber below the skeleton, a blowpipe P2 (outer diameter approximately 200 mm) that discharges the air blown from the blown air recovery device below the skeleton to the ground, a pipe P3 (outer diameter approximately 250 mm) that pours fill concrete into the work chamber below the skeleton after the caisson is poured, and a lubricant injection pipe P4 (outer diameter approximately 40 mm) that injects lubricant around the caisson. However, because the interior of the skeleton 1 is very narrow, interference with the structural rebars 2 to 5 cannot be avoided, and construction losses are incurred because the interfering portion J of the work floor 7 of the rebar assembly scaffolding 6 must be cut.

[0007] (3) Ease of assembly of inner formwork As shown in Figure 7, the Shaft LF3 for Slim Caissons combines what were originally separate pieces of equipment into one, so the outer diameter of the equipment is larger than that of the general Material Lock LF1 and Man Lock LF2 (see Figure 3). Therefore, if a bracket scaffolding 9 for assembling the inner formwork 8 of the main body 1 is constructed around the outer periphery of the Shaft LF3, only a narrow bracket scaffolding 9 with a distance D from the side wall of the main body 1 of around 500 mm or less can be installed, which significantly reduces the workability of assembling the inner formwork 8.

[0008] The present invention has been made in consideration of the above, and aims to provide a caisson construction method and construction auxiliary device that can improve the workability of constructing small-surface caissons. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the objectives, the caisson construction method of the present invention is a method of constructing the body of a caisson, and is characterized by comprising the steps of: installing an embedded formwork in a wall-like manner on one side of the thickness direction of the area in which concrete is to be poured of the body; attaching a protruding member to an engaging portion provided on the side of the embedded formwork facing the area in which concrete is to be poured; using a scaffolding board provided on the protruding member attached to the engaging portion as a foothold, arranging reinforcing bars in the area in which concrete is to be poured; and removing the protruding member from the engaging portion after arranging the reinforcing bars and before pouring concrete in the area in which concrete is to be poured.

[0010] In addition, another caisson construction method according to the present invention is characterized in that, in the above-mentioned invention, it further includes a step of attaching a separator for fixing the formwork to the engagement portion before pouring concrete into the intended pouring area.

[0011] In addition, the caisson construction assistance device of the present invention is a device that assists in the construction of a caisson's main body, and is characterized by comprising a wall-shaped embedded formwork provided on one side of the thickness direction of the area of ​​the main body where concrete is to be poured, an engaging portion provided on the side of the embedded formwork facing the area where concrete is to be poured, a protruding member that can be attached and detached to the engaging portion, and a scaffolding board provided on the protruding member.

[0012] Furthermore, another caisson construction auxiliary device according to the present invention is characterized in that, in the above-mentioned invention, it further comprises a separator for fixing the formwork that is removably attached to the engagement portion. [Effects of the Invention]

[0013] According to the caisson construction method of the present invention, a method for constructing a caisson skeleton includes the steps of: installing an embedded formwork wall on one side of the skeleton in the thickness direction of a planned concrete pouring area; attaching a protruding member to an engaging portion on the side of the embedded formwork facing the planned concrete pouring area; using a scaffolding board attached to the protruding member attached to the engaging portion as a scaffolding for placing rebar in the planned concrete pouring area; and removing the protruding member from the engaging portion after placing the rebar and before pouring concrete in the planned concrete pouring area. This method allows for easy installation of a rebar assembly scaffold at a desired position within the planned concrete pouring area. Furthermore, formwork can be easily installed on one side of the planned concrete pouring area. Since the installation of scaffolding and formwork in a narrow environment is not required, the construction workability of small-planar caissons can be improved.

[0014] In addition, according to another caisson construction method of the present invention, there is a further step of attaching a separator for fixing the formwork to the engagement portion before pouring concrete into the intended pouring area, which has the effect of improving the efficiency of the formwork solidification work.

[0015] Furthermore, the caisson construction assistance device of the present invention is a device for assisting the construction of a caisson's skeleton, and includes a wall-shaped embedded formwork provided on one side of the skeleton in the thickness direction of the planned concrete pouring area, an engagement portion provided on the side of the embedded formwork facing the planned concrete pouring area, an overhang member detachably attached to the engagement portion, and a scaffolding board provided on the overhanging member. This allows for easy installation of rebar assembly scaffolding at a desired position within the planned concrete pouring area. Furthermore, formwork can be easily installed on one side of the planned concrete pouring area. Since the installation of scaffolding and formwork in a narrow environment is not required, this has the effect of improving the construction workability of small-surface caissons.

[0016] In addition, another caisson construction auxiliary device according to the present invention further includes a separator for fixing the formwork that can be attached and detached freely to the engagement portion, thereby achieving the effect of improving the efficiency of the formwork solidification work. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 shows an embodiment of a caisson construction support device according to the present invention, where (1) is a schematic exploded perspective view and (2) is an enlarged view of the main part when in use. [Figure 2] FIG. 2 is a schematic diagram showing an embodiment of the caisson construction method according to the present invention. [Figure 3] Figure 3 is an explanatory diagram of the conventional caisson construction method, where (1) is the case of the pneumatic caisson construction method and (2) is the case of the slim caisson construction method. [Figure 4] FIG. 4 is a side cross-sectional view showing an example of reinforcement arrangement in a conventional slim caisson. [Figure 5] FIG. 5 shows an example of a conventional rebar-assembled scaffold, where (1) is a plan view and (2) is a side cross-sectional view. [Figure 6] FIG. 6 is a plan view showing an example of the layout of a conventional caisson temporary facility. [Figure 7] FIG. 7 is a side cross-sectional view showing a conventional inner formwork assembly state. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of a caisson construction method and construction support device according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiment.

[0019] (Caisson construction support device) First, an embodiment of the caisson construction support device according to the present invention will be described. As shown in Figure 1, the caisson construction support device 10 of this embodiment is a device that supports the construction of a caisson body with a circular cross-section when viewed from above, and comprises an embedded formwork 12, an engaging portion 14 provided on the side of the embedded formwork 12, an overhanging member 16, and a scaffolding board 18.

[0020] The embedded formwork 12 is made of precast concrete with a roughly arc-shaped cross section when viewed from above and a roughly rectangular plate-like shape when viewed horizontally. It is installed as a wall inside (one side in the thickness direction) the area where the concrete for the skeleton is to be poured. This embedded formwork 12 is used as an integrated formwork with the skeleton after concrete is poured. To improve the construction workability of small-planar caissons such as slim caissons, the embedded formwork 12 is preferably used as an inner formwork placed radially inside the skeleton. However, it may also be used as an outer formwork placed radially outside the skeleton. Multiple embedded formworks 12 can be used in combination. For example, by using multiple embedded formworks 12 and connecting their side ends laterally, the horizontal installation range of the formwork can be expanded. Furthermore, by connecting their upper and lower ends vertically, the vertical installation range of the formwork can be expanded. The embedded formwork 12 can be a precast concrete formwork or an extrusion-molded formwork.

[0021] The engaging portion 14 is used to attach the overhanging member 16 and is composed of multiple insert nuts 22 protruding at intervals from the side surface 20 of the buried formwork 12 facing the intended pouring area. The insert nuts 22 have a through-hole and a threaded groove formed on their inner circumferential surface. The insert nuts 22 are connected to insert anchors (not shown) inside the formwork 12. The insert nuts 22 are preferably spaced apart at the same height on the side surface 20 of the buried formwork 12. The insert nuts 22 may be removably attached with not only the overhanging member 16 but also separators for securing the formwork. Attaching separators to the insert nuts 22 can improve the efficiency of the formwork solidification process. The engaging portion 14 of the present invention is not limited to insert nuts; any structure may be used as long as the overhanging member 16 can be removably attached to the side surface 20 of the buried formwork 12. Furthermore, the engaging portion 14 may be provided not only on the side surface 20 of the buried formwork 12 but also on both sides of the buried formwork 12 .

[0022] The extension member 16 is made of a long L-shaped steel beam. One longitudinal end face of the extension member 16 is provided with a mounting plate 26 having a mounting hole 24 for mounting to an insert nut 22. The extension member 16 is detachably fixed to the insert nut 22 by threading a bolt 28 inserted into the mounting hole 24 of the mounting plate 26 into the insert nut 22. The extension member 16 mounted to the insert nut 22 extends in the normal direction from the side surface 20 of the buried formwork 12. Note that the extension member 16 of the present invention is not limited to an L-shaped steel beam, and may be made of steel materials such as other shaped steel beams, or may be made of other materials.

[0023] The scaffolding plank 18 is a long plate material that is installed between the top surfaces of the tip ends of the overhanging members 16 that are attached to insert nuts 22 at at least two locations at the same height. The scaffolding plank 18 may be installed by placing it on the top surface of a steel scaffolding girder that is installed between the overhanging members 16. The scaffolding plank 18 may be made of any material or structure that can support the weight of a worker, and may be made of, for example, steel, aluminum, wood, or other materials.

[0024] According to the above configuration, by installing the buried formwork 12 with a crane or the like, a formwork for the concrete structure can be easily installed on one side of the planned pouring area. Furthermore, by attaching the extension member 16 and scaffolding boards 18 to the buried formwork 12, a rebar assembly scaffold for the concrete structure can be easily installed at a desired position within the planned pouring area. Since there is no need to assemble the formwork and scaffolding in a narrow space, the construction workability of small-planar caissons can be improved. Therefore, construction work for slim caissons can be efficiently carried out in a narrow space.

[0025] (Caisson construction method) Next, an embodiment of the caisson construction method of the present invention using the above-mentioned construction auxiliary device 10 will be described with reference to Fig. 2, taking as an example a case where it is applied to the construction of a slim caisson. Note that in Fig. 2, for the sake of convenience, the reinforcing bars arranged on the outside of the skeleton (see the outer main bars 2 in Fig. 4, etc.) are not shown.

[0026] As shown in Figure 2, before the start of construction in step S1, multiple reinforcing bars extend from the top surface 30 of the completed lower-story skeleton to the planned pouring area A of the upper-story skeleton. Note that in Figure 2, only the inner main reinforcement bars 3 are shown, and the distribution bars 4, shear reinforcement bars 5, and outer main reinforcement bars 2 are not shown.

[0027] In the next step S2, the buried formwork installation process, a crane is used to install the buried formwork 12 in a wall shape on the upper surface 30 of the lower structure, radially inward of the planned pouring area A. As a result, the buried formwork 12 is placed in the narrow gap between the planned pouring area A and the slim caisson dedicated shaft LF3. It is desirable that the buried formwork 12 be divided circumferentially in advance (for example, divided at the positions indicated by the dashed lines in the figure) in consideration of the lifting capacity of the crane, and then connected to each other after each buried formwork 12 is placed on the upper surface 30 of the lower structure.

[0028] In the next step S3, the scaffolding girder / scaffolding installation process, the overhanging members 16 are attached to the insert nuts 22 at two locations at the same height on the side of the buried formwork 12, and then the scaffolding girders 32 are erected between the overhanging members 16 and the scaffolding boards 18 are placed on top of them, thereby constructing spot scaffolding 34 in a partial section within the planned concrete pouring area A. This spot scaffolding 34 is a local rebar assembly scaffold that is installed where and only when needed.

[0029] In the next step S4, the reinforcing bar assembly process, a worker M assembles the surrounding reinforcing bars from the spot scaffolding 34. The safety belt of the worker M may be connected to a life rope 36 or the like extending from a fixing jig installed on the outer main reinforcement 2 (not shown) to prevent the worker M from falling.

[0030] In the next step S5, a repeating process, the spot scaffolding 34 is reconstructed for each construction location, and the above-mentioned rebar assembly process is carried out. By repeating this process, temporary caissons such as the air pipe P1 (see Figure 6) can be installed without considering interference with the spot scaffolding 34.

[0031] In the next step S6, the scaffolding removal and separator installation process, after all rebar assembly work in the planned pouring area A is completed, the spot scaffolding 34 (extending member 16, scaffolding girder 32, scaffolding plank 18) is removed. Also, separators 38 for fixing the formwork may be attached to the remaining insert nuts 22. By using the insert nuts 22 in combination with the separator fixation, the efficiency of the formwork solidification work can be improved.

[0032] According to this embodiment, by installing the buried formwork 12 with a crane or the like, a formwork for the concrete structure can be easily installed on one side of the planned pouring area A. Furthermore, by attaching the protruding member 16 and scaffolding boards 18 to the buried formwork 12, a rebar assembly scaffold for the concrete structure can be easily installed at a desired position within the planned pouring area A. Since there is no need to assemble the formwork and scaffolding in a narrow environment, the construction workability of small-planar caissons can be improved. Therefore, construction work for caissons such as slim caissons can be carried out efficiently in narrow environments.

[0033] In addition, unlike conventional caisson construction methods, the rebar assembly scaffolding platform is not left in the planned pouring area, which improves the filling of concrete in planned pouring area A and ensures higher quality of the structure.

[0034] As described above, the caisson construction method of the present invention is a method for constructing a caisson skeleton, comprising the steps of: installing an embedded formwork wall on one side of the skeleton in the thickness direction of the planned concrete pouring area; attaching a projecting member to an engaging portion on the side of the embedded formwork facing the planned concrete pouring area; using a scaffolding board attached to the projecting member attached to the engaging portion as a scaffolding, placing rebar in the planned concrete pouring area; and removing the projecting member from the engaging portion after placing the rebar and before pouring concrete in the planned concrete pouring area. This method allows for easy installation of a rebar assembly scaffold at a desired position within the planned concrete pouring area. Furthermore, formwork can be easily installed on one side of the planned concrete pouring area. Since the installation of scaffolding and formwork in a narrow environment is not required, the construction workability of small-planar caissons can be improved.

[0035] In addition, according to another caisson construction method of the present invention, there is a further step of attaching a separator for fixing the formwork to the engagement portion before pouring concrete into the intended pouring area, thereby making it possible to improve the efficiency of the formwork solidification work.

[0036] Furthermore, the caisson construction assistance device of the present invention is a device for assisting the construction of a caisson's skeleton, and includes a wall-shaped embedded formwork provided on one side of the skeleton in the thickness direction of the planned concrete pouring area, an engagement portion provided on the side of the embedded formwork facing the planned concrete pouring area, an overhang member detachably attached to the engagement portion, and a scaffolding board provided on the overhanging member. This allows for easy installation of rebar assembly scaffolding at a desired position within the planned concrete pouring area. Furthermore, formwork can be easily installed on one side of the planned concrete pouring area. Since the installation of scaffolding and formwork in a narrow environment is not required, the construction workability of small-planar caissons can be improved.

[0037] In addition, another caisson construction auxiliary device according to the present invention further includes a separator for fixing the formwork that can be attached and detached to the engagement portion, thereby making it possible to improve the efficiency of the formwork solidification work. [Industrial Applicability]

[0038] As described above, the caisson construction method and construction auxiliary device of the present invention are useful for caissons used for bridge foundations, vertical shafts, etc., and are particularly suitable for improving the construction workability of small-surface caissons. [Explanation of symbols]

[0039] 10 Caisson construction auxiliary equipment 12 Buried formwork 14 Engagement portion 16 Projecting member 18 Scaffolding Planks 20 Side 22 Insert nut 24 mounting holes 26 Mounting plate 28 volts A. Planned pouring area M worker

Claims

1. A method for constructing a caisson body, A caisson construction method characterized by comprising the steps of: installing an embedded formwork in a wall-like manner on one side of the thickness direction of the planned concrete pouring area of ​​the body; attaching a protruding member to an engaging portion provided on the side of the embedded formwork facing the planned concrete pouring area; using a scaffolding board provided on the protruding member attached to the engaging portion as a foothold to arrange reinforcing bars in the planned concrete pouring area; and removing the protruding member from the engaging portion after arranging the reinforcing bars and before pouring concrete in the planned concrete pouring area.

2. A caisson construction method as described in claim 1, further comprising a step of attaching a separator for fixing the formwork to the engagement portion before pouring concrete into the intended pouring area.

3. A device that assists in the construction of a caisson body, A caisson construction auxiliary device characterized by comprising a wall-shaped embedded formwork provided on one side of the thickness direction of the planned concrete pouring area of ​​the main body, an engaging portion provided on the side of the embedded formwork facing the planned concrete pouring area, a protruding member that can be attached and detached to the engaging portion, and a scaffolding board provided on the protruding member.

4. A caisson construction auxiliary device as described in claim 3, further comprising a separator for fixing the formwork that is detachably attached to the engagement portion.

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