JP7431142B2 - Construction method of underground structure and scaffolding structure - Google Patents

Description

The present invention relates to a method for constructing an underground structure and a scaffolding structure used therein.

Conventionally, deep foundations are constructed by excavating a shaft in the ground, assembling a reinforcing cage inside the shaft, and pouring concrete (for example, see Patent Documents 1 and 2).

For example, Patent Document 1 describes placing concrete using a tremie pipe in the center of a shaft, and Patent Document 2 describes using a working scaffold with a floating member provided on the lower surface of the scaffold member. , describes that when pouring concrete into a shaft, this work scaffold is floated on top of the concrete and compaction work is performed on the scaffold.

Japanese Patent Application Publication No. 06-306864 Japanese Patent Application Publication No. 08-120913

However, when constructing a large-scale deep foundation using the method described above, it takes a lot of effort to pour concrete, and it is especially difficult to fill in areas with dense reinforcement. Therefore, there has been a need for a method that can easily place concrete and improve the efficiency of construction work.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a method of constructing an underground structure, etc., which can improve the efficiency of construction work.

A first invention to achieve the above-mentioned object is a method for constructing an underground structure, which includes a step of arranging a reinforcing material on the outer periphery of a shaft formed in the ground, and pouring concrete into the shaft. and, when placing concrete, a scaffold board having a casting hole for pouring concrete on the outer periphery of the shaft is provided at a height of the upper end of the reinforcing material. , a method for constructing an underground structure, characterized in that the pumped concrete is placed at the outer periphery of the shaft through the placing hole.

In the present invention, when constructing an underground structure such as a large-scale deep foundation, a scaffold board is installed at the upper end of the reinforcing material at the outer periphery of a shaft where reinforcing material such as reinforcing bars and shaped steel is placed, Concrete is pumped and placed using the pouring hole. This allows concrete to be filled quickly and reliably even when reinforcement is densely arranged around the outer circumference of a shaft, and allows workers on scaffolding boards to easily perform various tasks related to concrete placement. . Therefore, construction work for underground structures can be made more efficient.

It is preferable that the scaffold board is fixed to the reinforcing member by a fixing part disposed in a through hole of the scaffold board. Further, the fixing part is inserted into the fixing plate attached to the reinforcing member and the insertion hole of the fixing plate so as to protrude upward from the through hole, and both ends are placed on the scaffold board. It is desirable to have a beam-shaped insertion member.
The scaffold board can be fixed to the reinforcing member by the fixing part to prevent displacement. Moreover, by having the fixing portion have a bolt-like structure including the fixing plate and the insert material as described above, the scaffold board can be securely fixed with a simple mechanism.

As the reinforcing material, it is desirable to arrange a vertically oriented steel section on the outer periphery of the shaft.
By using high-strength steel sections as reinforcing materials for underground structures, it is possible to save labor in reinforcing work compared to placing a large number of reinforcing bars.

A second invention is a scaffolding structure used when pouring concrete in a shaft, which is provided at the height of the upper end of a reinforcing member placed on the outer periphery of the shaft. This is a scaffold structure characterized by comprising a scaffold board having a pouring hole for pouring concrete.

According to the present invention, it is possible to provide a method for constructing an underground structure, etc., which can improve the efficiency of construction work.

A diagram showing a deep foundation 10. A diagram showing a striped H-beam. The figure explaining the construction method of the deep foundation 10. The figure explaining the construction method of the deep foundation 10. The figure explaining the construction method of the deep foundation 10. The figure explaining the construction method of the deep foundation 10. FIG. 2 is a diagram showing a concrete placing system 100 and a scaffold board 200. FIG. 3 is a diagram showing a scaffolding board 200 and a fixing part 230. FIG. 3 is a diagram illustrating the placement of concrete 9. FIG. 3 is a diagram illustrating the placement of concrete 9.

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

(1. Deep foundation 10)
FIG. 1 is a diagram showing a deep foundation 10, which is an underground structure constructed by a construction method according to an embodiment of the present invention.

The deep foundation 10 is a large-diameter deep foundation, and is used as a foundation for bridge piers and the like.

The deep foundation 10 is constructed by pouring concrete 9 into a shaft 2 formed in the ground 1. The shaft 2 and the deep foundation 10 have a circular plane. A steel ring (not shown) is provided on the wall of the shaft 2, and a spray material is sprayed onto the ring. Alternatively, liner plates may be provided on the wall surface, or rock bolts may be provided by spraying on the wall surface.

At the outer periphery of the deep foundation 10, reinforcing materials such as outer band reinforcing bars 5, outer steel frames 6, inner band reinforcing bars 7, and inner steel frames 8 are buried in concrete 9. Note that the outside refers to the side closer to the wall surface of the shaft 2, and the inside refers to the side closer to the center of the plane of the shaft 2.

The outer band reinforcing bars 5 are reinforcing bars located at the outermost part of the shaft 2 (deep foundation 10) and arranged along the circumferential direction of the shaft 2. The outer band reinforcing bars 5 are arranged circumferentially on a plane within the shaft 2. The outer band reinforcing bars 5 are installed at predetermined intervals in the vertical direction.

The outer steel frame 6 is a vertical steel section arranged inside the outer band reinforcing bar 5, and in this embodiment, a striped H section steel is used. The striped H-shaped steel is an H-shaped steel in which a protruding strip a extending in the flange width direction is provided on the flange surface, as shown in FIG.

A plurality of outer steel frames 6 are installed at predetermined intervals along the circumferential direction of the shaft 2, with the width direction of the web aligned with the radial direction of the shaft 2. Further, in this embodiment, a plurality of outer steel frames 6 are used in a vertically connected manner by bolt connection using attachment plates 63.

The inner band reinforcing bars 7 are reinforcing bars located inside the outer steel frame 6 and arranged along the circumferential direction of the shaft 2. The inner band reinforcing bars 7 are arranged in a double inner and outer concentric circle on a plane inside the shaft 2. The inner band reinforcing bars 7 are installed at predetermined intervals in the vertical direction.

The inner steel frame 8 is a vertical steel section arranged inside the inner band reinforcing bar 7, and in this embodiment, a striped H section steel is used. A plurality of inner steel frames 8 are installed at predetermined intervals along the circumferential direction of the shaft 2, with the width direction of the web aligned with the radial direction of the shaft 2. Further, in this embodiment, a plurality of inner steel frames 8 are connected vertically by bolt connection using attachment plates 83.

Note that reference numeral 3 in FIG. 1 is an installation stand 3 used for installing the outer steel frame 6 and the inner steel frame 8, and in the deep foundation 10, the installation stand 3 is also buried in the concrete 9. Further, reference numeral 4 in FIG. 1 is a bottom concrete for fixing the position of the installation base 3, and the above-mentioned concrete 9 is placed on the bottom concrete 4.

(2. Method of constructing deep foundation 10)
Next, a method for constructing the deep foundation 10 will be explained with reference to FIGS. 3 to 6 and the like.

In this embodiment, after excavating the ground 1 to form a shaft 2, an installation stand 3 is provided at the bottom of the shaft 2, as shown in FIG. The installation stand 3 has an H-shaped steel 30 and a connecting member 31. In addition, in FIG. 3, (a) is a view of the shaft 2 viewed from above, and (b) is a view showing a vertical cross section of the bottom of the shaft 2. This also applies to subsequent FIGS. 4 and 5.

The H-shaped steel 30 is arranged along the radial direction of the shaft 2 with the width direction of the web aligned with the vertical direction. A plurality of H-beams 30 are provided radially at intervals along the circumferential direction of the shaft 2. The upper flange of the H-shaped steel 30 is provided with holes (not shown) used for fixing an outer steel frame 6 and an inner steel frame 8, which will be described later.

The connecting member 31 connects a plurality of H-beams 30 lined up in the circumferential direction of the shaft 2, and maintains a distance between adjacent H-beams 30. For example, an angle member is used as the connecting member 31, and it is arranged in a double concentric circle shape inside and outside the shaft 2 on a plane inside the shaft 2. The connecting member 31 is joined to the upper flange of the H-beam 30 with bolts or the like.

At the bottom of the shaft 2, leveling concrete 33 is poured around the outer periphery of the shaft 2 as necessary to adjust unevenness. The H-beam 30 is marked on the leveled concrete 33 and installed at a predetermined position on the leveled concrete 33. The H-beam 30 is fixed to leveled concrete 33 or the ground 1 below it by anchors 34.

In this embodiment, next, as shown in FIG. 4, outer band reinforcing bars 5 and outer steel frames 6 are installed. Here, first, bottom concrete 4 is placed at the bottom of the shaft 2, and the position of the installation stand 3 is fixed. The bottom concrete 4 is cast so that the upper part of the H-beam 30 is exposed, taking into account the work of fixing the outer steel frame 6 and the inner steel frame 8, which will be described later.

After the bottom concrete 4 is placed, outer band reinforcing bars 5 and outer steel frames 6 are placed around the outer periphery of the shaft 2. The outer band reinforcing bars 5 are fixed to mounting members (not shown) installed on the wall surface of the shaft 2. The outer steel frame 6 is installed inside the outer band reinforcement 5.

As shown in FIG. 4(b), an end plate 61 is provided at the lower end of the outer steel frame 6, and when installing the outer steel frame 6, a hole (not shown) in the end plate 61 is inserted into the upper flange of the H-beam 30. The shafts of headed bolts 64 are inserted into these holes from below, and nuts 65 are tightened onto the tips of the shafts protruding from the end plate 61. Thereby, the outer steel frame 6 is fixed to the upper flange of the H-section steel 30.

In this way, a plurality of outer steel frames 6 are arranged in the circumferential direction of the shaft 2. The upper ends of these outer steel frames 6 are connected to each other by a connecting member 62 arranged along the circumferential direction of the shaft 2.

The connecting members 62 are, for example, angle members, and are arranged in a concentric double inner and outer circle. The inner and outer connecting members 62 are joined to the inner flanges and outer flanges of the plurality of outer steel frames 6 arranged in the circumferential direction of the shaft 2 with bolts, etc., so that the upper ends of the plurality of outer steel frames 6 are connected to each other by the connecting members 62. Concatenated. The spacing between adjacent outer steel frames 6 is maintained by the connecting members 62, and the installation accuracy of the outer steel frames 6 is increased.

Next, as shown in FIG. 5, the inner band reinforcing bars 7 and the inner steel frame 8 are installed inside the outer steel frame 6 at a predetermined distance from the outer steel frame 6. The inner band reinforcing bars 7 can be fixed to a mounting jig (not shown) provided on the outer steel frame 6. The inner steel frame 8 is installed inside the inner band reinforcing bar 7. An end plate 81 is provided at the lower end of the inner steel frame 8, and the end plate 81 is fixed to the upper flange of the H-section steel 30 using head bolts 84 and nuts 85 in the same manner as before.

A plurality of inner steel frames 8 are arranged in the circumferential direction of the shaft 2. The upper ends of these inner steel frames 8 are connected in the same manner as the outer steel frames 6 using a connecting member 82 similar to the connecting member 62 described above.

In this way, the outer band reinforcing bars 5, the outer steel frames 6, the inner band reinforcing bars 7, and the inner steel frames 8 are installed in the shaft 2 as shown in FIG. 6(a). Thereafter, a part of the deep foundation 10 is constructed by placing concrete 9 in the shaft 2 as shown in FIG. 6(b). The concrete 9 is cast so that the upper ends of the outer steel frame 6 and the inner steel frame 8 are exposed, and the connecting members 62 and 82 are removed after the concrete 9 is cast and reused in a later process.

After that, as shown in FIG. 6(c), new outer band reinforcing bars 5, outer steel frames 6, and inner band reinforcing bars are placed above the outer band reinforcing bars 5, outer steel frames 6, inner band reinforcing bars 7, and inner steel frames 8 that were installed earlier. 7. Install the inner steel frame 8 in the same way as before. However, the lower ends of the outer steel frame 6 and the inner steel frame 8 are not fixed to the installation stand 3, but are connected to the upper ends of the lower outer steel frame 6 and inner steel frame 8 using attachment plates 63 and 83.

Then, new concrete 9 is placed above the concrete 9 that was previously placed, as shown in FIG. 6(d). The deep foundation 10 shown in FIG. 1 is constructed by repeating the steps shown in FIGS. 6(c) and 6(d).

(3. Placing concrete 9)
In this embodiment, concrete 9 is placed using a concrete placing system 100 shown in FIG. FIG. 7(a) is an elevation view of the concrete placement system 100, and FIG. 7(b) is a top view of the concrete placement system 100.

The concrete placement system 100 includes a pedestal 110, a distributor 120, a bucket 130, a float scaffold 140, and the like.

The pedestal 110 is a planar cross-shaped pedestal installed on the bottom concrete 4 at the center of the shaft 2, and its upper end is located at a higher position than the upper ends of the outer steel frame 6 and the inner steel frame 8.

The pedestal 110 is formed by combining a vertical support 111 and horizontal members 112 in multiple stages above and below. Further, a work scaffold 114 is disposed inside the pedestal 110, and a crossing scaffold 115 is disposed above the pedestal 110 in a planar cross shape.

The work scaffold 114 can be moved up and down within the pedestal 110 as shown by arrow b in FIG. 113. The brackets 113 are provided in a plurality of upper and lower stages on the pedestal 110.

The distributor 120 is a device for pumping and pouring the concrete 9 to the outer circumference of the shaft 2, and is provided on the pedestal 110.

The distributor 120 has a rotating part 121 and a pressure-feeding pipe 122, and is fixed on the pedestal 110 by a pedestal part 125.

The rotating portion 121 is a member extending in the horizontal direction. The rotating portion 121 can be manually rotated around the plane center of the shaft 2 by pulling a rope (not shown) attached to the tip.

The pressure-feeding pipe 122 is a pipe for pressure-feeding the concrete 9, and is installed along the turning portion 121. The pressure pipe 122 is connected to a concrete pump truck (not shown) on the ground. The pressure feeding pipe 122 can be rotated in a plane together with the turning section 121.

The discharge port at the tip of the pressure-feeding pipe 122 is arranged near the wall surface of the shaft 2. When the concrete 9 is being pumped and placed, a hose 124 is attached to the discharge port of the pressure pipe 122 to serve as a flow path for the concrete 9, and is suspended from the outer periphery of the shaft 2.

The bucket 130 is used to place concrete 9 in the center of the shaft 2, and is suspended into the shaft 2 by a lifting device (not shown) such as a crane while containing the concrete 9.

The floating scaffold 140 is placed on the bottom concrete 4, avoiding the planar position of the pedestal 110.

In addition, in this embodiment, a scaffold board 200 is provided in a circumferential manner at the outer circumference of the shaft 2 at the height of the upper ends of the outer steel frame 6 and the inner steel frame 8, and this scaffold board 200 is used to place the concrete 9. Perform work related to. Note that a staircase (not shown) is installed between the scaffolding board 200 and the crossing scaffolding 115, and it is possible to go back and forth between the scaffolding board 200 and the pedestal 110.

FIG. 8(a) is a plan view of the scaffolding board 200, and FIGS. 8(b) to 8(d) are the vertical directions along lines AA, BB, and CC in FIG. 8(a), respectively. FIG. 3 is a diagram showing a cross section.

The scaffolding board 200 has a fan-shaped plane whose inner and outer sides are approximately arc-shaped with a curvature along the outer periphery of the shaft 2 (the arc of the above-mentioned curvature is approximated by a straight line), and the casting hole 210 and the through hole 220 are formed. provided. In this embodiment, a plurality of scaffolding boards 200 are arranged in a circumferential manner along the outer periphery of the shaft 2, as shown in FIG. 7(b).

The pouring hole 210 is a hole for pouring concrete 9 on the outer periphery of the shaft 2, and is formed at a position avoiding the outer steel frame 6 and the inner steel frame 8. A plurality of driving holes 210 are provided at intervals in the circumferential direction of the shaft 2.

The pouring hole 210 is normally closed with a lid 211, and is opened by removing the lid 211 when pouring concrete 9. As shown in FIGS. 8(c) and 8(d), an insertion portion 213 inserted into the casting hole 210 is provided on the lower surface of the lid 211. An angle material or the like is used for the insertion portion 213, and it is arranged along the edge of the casting hole 210. Note that reference numeral 212 in FIGS. 8(c) and 8(d) is a handle provided on the top surface of the lid 211.

The through holes 220 are holes for fixing the scaffolding board 200 to the outer steel frame 6 and the inner steel frame 8, and are formed at positions corresponding to the outer steel frame 6 and the inner steel frame 8. In addition, a handrail (not shown) is also provided on the inner peripheral side of the upper surface of the scaffold board 200.

As shown in FIG. 8(b), the scaffold board 200 is provided with frame members 202 in the radial direction and circumferential direction of the vertical shaft 2 on the lower surface of the top plate 201, and the radial frame members 202 are connected to the outer steel frame 6. , placed on the connecting members 62, 82 of the inner steel frame 8. The above-mentioned casting holes 210 and through holes 220 are provided in the top plate 201, and the scaffolding board 200 is fixed to the outer steel frame 6 and the inner steel frame 8 using fixing parts 230 arranged inside the through holes 220.

The fixing part 230 has a fixing plate 231, an insert member 232, etc., and the scaffold board 200 and the fixing part 230 constitute a scaffold structure in the present invention.

A pair of fixing plates 231 are arranged so as to sandwich the upper end webs of the outer steel frame 6 and the inner steel frame 8 from both sides. At this time, the holes (not shown) in the fixing plate 231 communicate with the holes (not shown) in the web used for bolting the attachment plates 63 and 83, and the headed bolts are inserted into these holes from the fixing plate 231 side. 2, and tighten a nut onto the tip of the shaft protruding from the other fixed plate 231. As a result, the fixing plate 231 is attached to the web using fasteners 233 such as headed bolts and nuts.

Each fixing plate 231 is arranged so as to protrude upward from the through hole 220, and an insertion hole 234 is provided in this protruding portion. Beam-shaped inserts 232 are inserted into these insertion holes 234, and both ends of the inserts 232 are placed on the scaffold board 200 as shown in FIG. 8(d). Although a square steel pipe is used for the insertion member 232, the present invention is not limited to this.

The above fixing portions 230 fix the scaffolding board 200 so that it does not come off the outer steel frame 6 and the inner steel frame 8. The insertion rod 236 has a head and a shaft portion, and the head portion thereof is located on the insertion material 232 and the shaft portion passes through the insertion material 232 and is inserted into the through hole 220. It is installed to reach the inside. Further, a stopper 235 made of an L-shaped metal fitting or the like is also provided on the upper surface of the insertion member 232.

The stopper 235 and the insertion rod 236 are provided to sandwich the fixing plate 231, thereby preventing the insert material 232 from coming out of the insertion hole 234 of the fixing plate 231. Note that the reference numeral 236 in FIG. 8(d) is a handle provided on the upper surface of the insert member 232.

In this embodiment, the distributor 120 and the bucket 130 are used in combination to pour concrete 9 in multiple systems in parallel.

In casting by the distributor 120, the rotating part 121 rotates the pressure feeding pipe 122 to move the discharge port at the tip thereof to the position of the casting hole 210, and the hose 124 is attached to the discharge port.

Then, the cover 211 of the pouring hole 210 is removed, the hose 124 is passed through the pouring hole 210 and suspended at the outer periphery of the shaft 2, and the concrete 9 is force-fed from the concrete pump vehicle via the pressure-feeding pipe 122, and the concrete 9 is pumped through the shaft 2. Concrete 9 is poured around the outer periphery.

As a result, concrete 9 is quickly and reliably filled into the outer circumference of the shaft 2 where reinforcing materials such as the outer band reinforcing bars 5, the outer steel frames 6, the inner band reinforcing bars 7, and the inner steel frames 8 are densely packed. The lower end of the hose 124 is pulled up in accordance with the rise of the top end of the concrete 9.

On the other hand, concrete 9 is placed using a bucket 130 in the center of the shaft 2 where reinforcement is not arranged. By placing the concrete 9 in multiple systems in this manner, the work of placing the concrete 9 within the shaft 2 can be streamlined.

As shown in FIG. 9, the floating scaffold 140 rises as the top of the concrete 9 rises, and is always placed at the top of the concrete 9. The concrete 9 is poured in several stages, and the work scaffold 114 is raised at an appropriate timing as the concrete 9 pouring work progresses, and placed on the bracket 113 at an appropriate height. For example, when pouring concrete 9 to the top position shown in FIG. 9, a work scaffold 114 is placed in advance on a bracket 113 directly above the concrete 9. Compaction work of the concrete 9 and the like can be performed from these work scaffolds 114 and float scaffolds 140.

The casting by the distributor 120 is performed sequentially while rotating the pressure feed pipe 122 and changing the position of the casting hole 210, as shown by the arrow in FIG. Driving with the bucket 130 is performed at a position away from the driving hole 210, and the driving position is moved in accordance with the rotation of the pressure feed pipe 122. This prevents lifting of the bucket 130 and pouring by the distributor 120 from being vertical work.

Through the above operations, concrete 9 is placed as shown in FIG. 6(b). After pouring the concrete 9, the fixing part 230 is removed and the scaffolding board 200 is removed to be used in a later process. On the other hand, the pedestal 110 is left in the concrete 9 and buried. Note that illustration of the pedestal 110 is omitted in FIG. 1 and FIGS. 6(b) to 6(d).

As described above, according to the present embodiment, when constructing the deep foundation 10, the outer steel frame 6 and the inner steel frame 8 are installed at the outer periphery of the shaft 2 where reinforcing members such as the outer steel frame 6 and the inner steel frame 8 are arranged. A scaffolding board 200 is installed at the upper end, and the concrete 9 is pumped and placed using its casting hole 210. This makes it possible to quickly and reliably fill the concrete 9 even when reinforcement is densely arranged around the outer periphery of the shaft 2. Various construction-related works can be easily performed by workers on the scaffolding board 200. Therefore, the construction work of the deep foundation 10 can be made more efficient.

Furthermore, the scaffolding board 200 can be fixed to the outer steel frame 6 and the inner steel frame 8 by the fixing portion 230 to prevent positional displacement. In addition, the fixing portion 230 has a bar-shaped configuration including the fixing plate 231 and the insert member 232, so that the scaffold board 200 can be securely fixed with a simple mechanism.

In addition, in this embodiment, by using high-strength shaped steel (outer steel frame 6, inner steel frame 8) as a reinforcing material for the deep foundation 10, it is possible to save labor in reinforcing work compared to when arranging a large number of reinforcing bars. I can do it.

However, the present invention is not limited to the above embodiments. For example, the reinforcement arrangement within the deep foundation 10 is not limited to the above-mentioned example, and any reinforcing material may be provided on the outer periphery. For example, it is possible to omit the inner steel frame 8, and the number of stages of the outer band reinforcing bars 5 and the inner band reinforcing bars 7 can also be changed. Moreover, it is also possible to use steel sections other than striped H-section steel as the outer steel frame 6 and the inner steel frame 8. Further, in the center of the shaft 2, it is also possible to apply a driving method other than the bucket 130.

Further, the shape, configuration, etc. of the scaffolding board 200 are not limited to those described above, as long as it has the casting hole 210. In addition to the above-mentioned example, the fixing part 230 may be any other member as long as it can fix the scaffold board 200 to the reinforcing material on the outer periphery of the shaft 2.

Further, in this embodiment, an example of constructing the deep foundation 10 as an underground structure has been described, but the construction method of this embodiment can also be applied to the case of constructing other underground structures.

Although preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that those skilled in the art can come up with various changes or modifications within the scope of the technical idea disclosed in this application, and these naturally fall within the technical scope of the present invention. Understood.

1: Ground 2: Shaft 3: Installation platform 4: Bottom concrete 5: Outer band reinforcement 6: Outer steel frame 7: Inner band reinforcement 8: Inner steel frame 9: Concrete 10: Deep foundation 100: Concrete placement system 110: Frame 120 : Distributor 130: Bucket 140: Float scaffolding 200: Scaffolding board 210: Casting hole 220: Through hole 230: Fixed part 231: Fixed plate 232: Insert material

Claims (5)

A method for constructing an underground structure, the method comprising:
A step of placing reinforcing material around the outer periphery of a shaft formed in the ground;
a step of pouring concrete into the shaft;
has
When pouring concrete, a scaffold board having a pouring hole for pouring concrete on the outer periphery of the shaft is provided at the height of the upper end of the reinforcing material, and the pumped concrete is poured into the concrete. A method for constructing an underground structure, characterized in that the concrete is poured at the outer periphery of the shaft through a hole. 2. The method of constructing an underground structure according to claim 1, wherein the scaffold board is fixed to the reinforcing material by a fixing part arranged in a through hole of the scaffold board. The fixed part is
a fixing plate attached to the reinforcing material so as to protrude upward from the through hole;
a beam-shaped insertion material that is inserted into the insertion hole of the fixing plate and has both ends placed on the scaffolding board;
The method for constructing an underground structure according to claim 2, comprising: The method for constructing an underground structure according to any one of claims 1 to 3, characterized in that, as the reinforcing material, a vertically oriented steel section is arranged on the outer periphery of the shaft. A scaffolding structure used when pouring concrete in a shaft,
The scaffolding board is provided at the height of the upper end of the reinforcing material arranged on the outer periphery of the shaft, and has a casting hole for pouring concrete on the outer periphery of the shaft. scaffolding structure.

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