JP2008138488A - Construction method of underground structure, and underground structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method of an underground structure superior in working efficiency by which a large bearing force against an axial force can be secured. <P>SOLUTION: In the construction method of a caisson type pile 1 in which a concrete 4 is driven into an excavated hole 5 formed by excavating the ground 50, a plurality of spiral columns 2 having H-shaped steels 21 and spiral reinforcements 22 spirally arranged around the H-shaped steels 21, respectively, are arranged in a standing manner at intervals along a hole wall 5a of the excavated hole. A concrete is placed on a bottom face 5b of the excavated hole so that the lower ends of the spiral columns may be buried. Then, the concrete is placed around the spiral columns 2 to construct a wall part 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for constructing underground structures such as piles and caissons, and an underground structure.

Conventionally, a method for constructing a deep foundation pile made of reinforced concrete by forming a drilling hole while protecting the hole wall of the excavated ground with a liner plate, assembling a reinforcing bar in the drilling hole, and placing concrete is known. (See Patent Documents 1 and 2, etc.).
JP 2000-144740 A JP-A-8-27784

  However, the work of assembling reinforcing bars in a narrow excavation hole is complicated and inefficient, and is a work at a high place, so it is necessary to assemble a scaffold on a large scale.

  In addition, since the pile is a long member on which axial force mainly acts, if it is a member that is difficult to buckle even with large axial force, the cross section is reduced to reduce the excavation amount of the ground and reduce the overall construction cost. Can be suppressed.

  Then, this invention aims at providing the construction method and underground structure of an underground structure which are excellent in workability, and can ensure big proof strength with respect to an axial force.

  In order to achieve the above object, a method for constructing an underground structure according to the present invention is a method for constructing an underground structure in which concrete is driven into an excavation hole formed by excavating the ground. A plurality of steel rebar members having helical rebars arranged in a spiral around the periphery of the steel rebar members at intervals along the hole wall of the excavation hole, and the lower end of the steel rebar member is embedded Concrete is cast on the bottom surface of the excavation hole, and the trunk is constructed by placing concrete around the steel rebar member.

  Further, it is a method for constructing an underground structure in which concrete is driven into a drilling hole formed by excavating the ground, and the reinforcing bars extending along the hole wall of the drilling hole are vertically spaced. A plurality of steel rebar members having a steel frame and spiral rebars arranged in a spiral manner around the steel frame are arranged at intervals along the inside of the band rebar, and the steel rebar member A plurality of strip reinforcing bars extending along the inside are arranged at intervals in the vertical direction, and a bottom plate is constructed by placing concrete on the bottom surface of the excavation hole so that the lower end of the steel rebar member is buried And constructing a wall part by placing concrete around the steel rebar member and the belt reinforcing bar, and constructing a top part for transmitting a load from above to the wall part at an upper end part of the wall part. Features.

  Furthermore, it is a construction method of an underground structure constructed by driving concrete into an excavation hole formed by excavating the ground, and includes a steel rebar member having a steel frame and a helical rebar arranged in a spiral manner around the steel frame. A plurality of standing erections along the hole wall of the excavation hole, a substantially U-shaped link bar in a plan view is bridged between the steel bar members, and the lower end of the steel bar member is embedded. Concrete is cast on the bottom surface of the excavation hole to construct a bottom plate, and a wall is constructed by placing concrete around the steel rebar member, and a load from above is applied to the upper end of the wall. It is characterized by constructing a top to be transmitted to the wall.

  And it is a construction method of an underground structure that is constructed by driving concrete into an excavation hole formed by excavating the ground, and a steel rebar member having a steel frame and a helical rebar arranged spirally around the steel frame Standing along the hole wall of the excavation hole, the same steel rebar member is installed next to each other so that the spiral rebars overlap in plan view, and the spiral rebars overlap in plan view in this way. By placing concrete on the bottom surface of the excavation hole to construct a bottom plate so that the lower end of a plurality of the steel rebar members erected is embedded, and placing concrete around the steel rebar member A wall part is constructed, and a top part for transmitting a load from above to the wall part is constructed at the upper end part of the wall part.

  The underground structure of the present invention is an underground structure constructed by driving concrete into an excavation hole formed by excavating the ground, and includes a steel frame and a plurality of assemblies erected around the steel frame. The steel bar member having a reinforcing bar and a spiral reinforcing bar that spirally surrounds the outer side of the assembled reinforcing bar and protrudes outward from the assembled reinforcing bar is formed between the protruding portions of the helical reinforcing bar members of the adjacent steel reinforcing bar members. It arrange | positions so that it may overlap by planar view, the inside of the said hole wall is surrounded by several steel frame reinforcing bar members, and concrete is cast around those steel frame reinforcing bar members.

  Here, a wall portion formed in a cylindrical shape by concrete placed around the steel rebar member, a bottom plate for closing the lower end side of the wall portion, and a top plate for closing the upper end side of the wall portion It can be set as the structure provided.

  In the construction method of the underground structure of the present invention configured as described above, a plurality of steel rebar members assembled in advance by a steel frame and a helical rebar are erected in the excavation hole, and concrete is placed around the perforated hole. Build the body of the structure.

  For this reason, the assembling work of the rebar in the excavation hole can be greatly reduced, and the underground structure can be constructed efficiently.

  In addition, since steel-reinforced steel members are high-axial force members that use steel frames, the cross-section can be reduced compared to the construction of underground structures using reinforced concrete, resulting in less excavation and shorter construction periods. can do.

  Moreover, in the method of arrange | positioning a strip reinforcing bar to the outer peripheral side and inner peripheral side of a steel frame reinforcing member, the yield strength of an underground structure can be increased by constraining the concrete between steel frame reinforcing members by a band reinforcing bar. Furthermore, if the reinforcing bars extend in the circumferential direction, the extending directions of the reinforcing bars do not intersect with each other, so that they can be easily arranged even in the excavation hole.

  In addition, the proof strength of the underground structure can be increased as an interlocking bar arrangement in which the steel rebar members are connected by a simple operation of bridging the U-shaped link bars between the steel rebar members.

  Furthermore, if it is a method of connecting a part of the spiral rebar that constitutes the steel rebar member by overlapping it with the spiral rebar of the adjacent steel rebar member, the work in the excavation hole can be greatly reduced. Very good.

  Then, by making the helical rebar project from the assembled rebar for attaching the helical rebar to the steel rebar member, the helical rebars of the adjacent steel rebar members can be accurately overlapped in a plan view. An underground structure with high strength of rocking reinforcement can be obtained.

  In addition, since a bottom plate is disposed on the lower end side of the high strength wall portion in which the steel rebar member is embedded, and a top plate is disposed on the upper end side, a hollow underground structure can be constructed. Compared to the construction of a solid structure, the amount of concrete placed can be greatly reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a cut perspective view showing a schematic configuration of a deep foundation pile 1 as an underground structure of the present embodiment.

  First, to explain from the configuration, the deep foundation pile 1 is a pile foundation constructed in an excavation hole 5 obtained by excavating the ground into a columnar shape, and a bottom plate 12 having a substantially circular shape in plan view formed on the bottom surface and its peripheral edge. A wall portion 11 as a body portion standing upright in a cylindrical shape, and a top plate 13 (see FIG. 4C) as a top portion spanned between the upper ends of the wall portion 11.

  Reinforcing bars 12a,... Are arranged on the bottom plate 12, and the thickness, the amount of reinforcing bars, and the concrete are set so as to be rigid enough to withstand the transfer of the overload transmitted through the wall 11 to the ground. Strength etc. are set.

  Moreover, the wall part 11 is arrange | positioned in the outer peripheral side and inner peripheral side of spiral column 2, ... as the reinforced steel member erected by the circumferential direction at intervals, and the spiral column 2, ... It is mainly comprised by the reinforced steel bars 3, ... and the concrete 4 cast around them.

  As shown in the perspective view of FIG. 2 (a), the spiral column 2 has an H-section steel 21 arranged as a steel frame in the center, and is erected substantially parallel to the four corners at a distance from the H-section steel 21. The assembled reinforcing bars 23,... And the helical reinforcing bars 22 that surround the outer periphery of the assembled reinforcing bars 23,.

  The H-section steel 21 is a member that mainly bears a load in the vertical direction. As shown in FIG. 2B, the H-section steel 21 is replaced with the spiral column 2A using a steel pipe 24 as a steel frame instead of the H-section steel 21. You can also

  A plurality of spacers (not shown) are attached to the side surface of the H-shaped steel 21 at intervals in the longitudinal direction, and the assembly reinforcing bars 23,... Are attached via the spacers.

  And, on the outer periphery of the assembled reinforcing bars 23,..., For example, a small-diameter deformed PC steel rod is wound in a spiral shape having a substantially rectangular shape in plan view and arranged as a helical reinforcing bar 22. The helical rebar 22 is disposed without contacting the H-section steel 21 because the assembly rebars 23,... Are disposed at positions away from the H-section steel 21.

  The helical rebar 22 has a function of constraining the concrete filled between the H-section steel 21 and the buckling of the H-section steel 21 is thereby prevented.

  The helical rebar 22 does not need to be continuous from top to bottom with respect to a single H-section steel 21, and for example, a member formed in a spiral spring shape is spaced apart in the longitudinal direction of the H-section steel 21. A plurality of such arrangements can be placed and extended in the longitudinal direction to connect the ends to each other, thereby completing a form as shown in FIG.

  FIG. 3 shows a cross-sectional view of the wall portion 11 in which a plurality of spiral columns 2 manufactured in this manner are arranged at intervals in the circumferential direction.

  As shown in FIG. 3, the spiral column 2 is disposed substantially at the center in the thickness direction of the wall portion 11, and the strip reinforcing bars 3, 3 that are substantially circular in plan view on the outer peripheral side and the inner peripheral side are respectively Be placed. As shown in FIG. 1, a plurality of the reinforcing bars 3 are arranged at intervals in the vertical direction.

  3, the concrete 4 filled between the H-shaped steel 21 and the helical rebar 22 is constrained by the helical rebar 22, and between the spiral columns 2. 3 is constrained in the circumferential direction by the spiral columns 2... And is constrained in the radial direction (thickness direction of the wall portion 11) by the strip reinforcing bars 3 and 3. Therefore, buckling hardly occurs even if a large axial force acts in the vertical direction.

  Next, the construction method of the deep foundation pile 1 of this Embodiment and its effect | action are demonstrated, referring FIG.

  First, as shown in FIG. 4A, the excavation hole 5 that matches the outer shape of the deep foundation pile 1 is excavated in the ground 50. This excavation is performed while protecting the hole wall 5a with, for example, a liner plate or sprayed concrete.

  Then, when excavation is completed to a predetermined depth, a gantry 6 for installing the spiral column 2 in a circumferential shape along the hole wall 5a is installed on the bottom surface 5b. The gantry 6 may be provided continuously, or may be intermittently arranged in the circumferential direction only at a position where the spiral column 2 is installed.

  Moreover, the belt reinforcement 3 formed in the planar view substantially circular shape is arrange | positioned in the position which entered a little inside from the hole wall 5a. If the rebar 3 is formed in a circular shape before being inserted into the excavation hole 5, it can be installed simply by hanging it at a predetermined position and fixing it to a support material (not shown).

  This vertical arrangement of the outer peripheral side reinforcing bars 3,... Is performed, for example, until the height of one spiral column 2 is reached.

  And the spiral column 2 manufactured beforehand in the factory or the production yard on the ground is arrange | positioned in the inner peripheral side of this belt reinforcement 3, .... Since the spiral column 2 may be installed at a predetermined position of the gantry 6, it can be easily erected.

  In this way, the lower spiral columns 2,... Are arranged, and the rebar 12a of the portion embedded in the bottom plate 12 and the belt reinforcing bars 3,... On the inner peripheral side are assembled (not shown in FIG. 4, (See FIG. 1). And the concrete of the rising part from the baseplate 12 and the baseplate 12 upper surface of the wall part 11 is laid.

  By embedding the lower end of the spiral column 2 in the bottom plate 12 in this way, the wall portion 11 and the bottom plate 12 are firmly joined, and the upper load acting on the wall portion 11 can be reliably transmitted to the bottom plate 12.

  In addition, after the concrete of the bottom plate 12 reaches a predetermined strength, a scaffold is assembled on the bottom plate 12 and the strip reinforcing bars 3,... On the inner peripheral side of the wall portion 11 are disposed, and the inner periphery of the wall portion 11 is also disposed. The face formwork is assembled and concrete for the lower stage of the wall 11 is placed.

  As shown in FIG. 4 (b), the upper ends of the spiral columns 2,. The lower end of the upper spiral column 2 is joined to the upper end.

  Before installing the upper spiral columns 2,..., The upper outer peripheral side reinforcing bars 3,.

  And the process of a joint is given with respect to the upper end surface of the wall part 11 in which concrete was previously cast, and the inner periphery side reinforcing bars 3,.

  Subsequently, the concrete for the upper stage of the wall portion 11 is placed, and after the concrete of the wall portion 11 is launched to a predetermined height, a mold and a support for forming the lower surface of the top plate 13 are installed. And concrete is cast in the upper end of the top plate 13 and the wall part 11, and the deep foundation pile 1 as shown in FIG.4 (c) is constructed | assembled.

  Since the hollow portion 14 is formed inside the deep foundation pile 14 constructed in this way, the amount of placing concrete can be greatly reduced as compared with the case where a solid pile body is constructed. .

  Moreover, since the dead weight is reduced by the amount made hollow, the overload can be increased instead.

  In the construction method of the deep foundation pile 1 of the present embodiment configured as described above, the spiral columns 2,... Assembled in advance in the excavation hole 5 by the H-section steel 21 and the helical rebar 22 are erected. Concrete 4 is laid around and the wall 11 of the deep foundation pile 1 is constructed.

  For this reason, the assembling work of the reinforcing bar in the excavation hole 5 is only the work for the reinforcing bar 12a of the bottom plate 12, the reinforcing bar 3 and the like, and the work amount can be greatly reduced, which is efficient.

  Moreover, since the spiral column 2 is a high axial force member using a steel frame, it can support a large overlay load even with a pile having a small cross section as compared with a case where an underground structure is constructed with reinforced concrete. The amount of excavated soil in the excavation hole 5 can be reduced.

  Furthermore, by placing the necessary steel material in the vertical direction with steel instead of reinforcing bars, it is possible to avoid overcrowding and improve workability, and problems such as insufficient concrete filling do not occur.

  Further, by extending the steel bars 3,... In the circumferential direction in the excavation hole 5 and restraining the concrete 4 between the spiral columns 2,. it can. Furthermore, if only the strip reinforcing bars 3,... Extending in the circumferential direction are used, the extending directions of the reinforcing bars do not intersect with each other, so that even the inside of the excavation hole 5 can be easily assembled.

  Hereinafter, Example 1 of a form different from the above-described embodiment will be described. The description of the same or equivalent parts as those described in the above embodiment will be given the same reference numerals.

  In Example 1, the rebar 3 described in the above embodiment is not used, and the spiral columns 2 and 2 are connected by the link bars 7 as shown in FIG.

  The link bar 7 is a member formed by bending both ends of a reinforcing bar substantially at a right angle so as to have a substantially U-shape in plan view, and includes a main body 71 and legs 72 and 72 on both sides thereof.

  Then, the link bar 7 configured as described above is bridged between adjacent rebars 23 and 23 of the spiral columns 2 and 2 arranged at intervals in the circumferential direction, as shown in FIG. 5A. . That is, the bent portion at the boundary between the main body 71 and the leg 72 is hooked on the rebar 23 and fixed with a binding wire or the like.

  Further, the link bars 7 are bridged between the outer peripheral side and the inner peripheral side between the spiral columns 2 and 2, and connect the spiral columns 2,.

  Such a link bar 7 having a substantially U-shape in plan view with one side open can be easily inserted from the lateral direction and can be easily bridged between the spiral columns 2 and 2.

  Further, by arranging the link bars 7, the reinforcing bars between the spiral columns 2 and 2 become interlocking bars that are continuous in the circumferential direction, and the proof stress of the wall portion 11 </ b> A can be increased.

  Other configurations and functions and effects are substantially the same as those in the above-described embodiment, and thus description thereof is omitted.

  Hereinafter, Example 2 of a form different from the above-described embodiment will be described. The description of the same or equivalent parts as those described in the above embodiment will be given the same reference numerals.

  In the second embodiment, a deep pile 1B as an underground structure provided with a structure in which a part of adjacent steel rebar members overlap in plan view will be described with reference to FIGS.

  As shown in FIG. 7, the wrapping column 8 as a steel rebar member arranged in the deep foundation pile 1B of the second embodiment includes an H-shaped steel 81 arranged as a steel frame in the center and H-shapes near its four corners. It is mainly comprised from the assembly rebar 83 standing upright in parallel with some distance from the steel 81, and the helical rebar 82 which spirally surrounds the outer periphery of the assembly rebar 83,.

  In this spiral reinforcing bar 82, both sides corresponding to both flanges of the H-shaped steel 81 protrude outward from the assembled reinforcing bars 83,... To form protrusions 82a and 82a. That is, the spiral reinforcing bar 82 is formed in a substantially rectangular shape in plan view, but unlike the above-described embodiment, the helical reinforcing bar 82 is not bent at the position of the assembled reinforcing bar 83. Bend in position.

  6, the plurality of wrapping columns 8,... Are arranged such that the protrusions 82a overlap the protrusions 82a of the adjacent wrapping columns 8 in plan view.

  In order to overlap the wrapping columns 8, 8, for example, after one wrapping column 8 is erected in the excavation hole 5, the other wrapping column 8 is suspended to the same height in the excavation hole 5. This is done by moving in the lateral direction and inserting the protrusion 82a of the other wrap column 8 into the protrusion 82a of the other wrap column 8.

  That is, by causing the spiral reinforcing bar 82 to protrude outward from the assembled reinforcing bars 83,..., The wrapping columns 8, 8 can be easily overlapped without being obstructed by the assembled reinforcing bars 83,. it can. Moreover, it can prevent that the assembly rebar 83, ... becomes a stopper and penetrates deeply and the overlap becomes too large.

  Further, in the portion where the protrusions 82a and 82a overlap each other, the insertion bar 9 can be inserted after the overlapping as shown in FIG. 6 so that the overlap between the wrapping columns 8 and 8 is not released. .

  Further, the insertion strength 9 can increase the connection strength between the wrapping columns 8, 8.

  In the deep foundation pile 1B of Example 2 configured in this way, the protruding portion 82a of the spiral reinforcing bar 82 that constitutes the wrapping column 8 is connected to the protruding portion 82a of the spiral reinforcing bar 82 of the adjacent wrapping column 8 from the lateral direction. Since both can be piled up only by inserting, the operation | work in the excavation hole 5 can be reduced significantly and it is excellent in workability.

  In addition, since such superposition can be performed in a state where the lap column 8 is suspended by a crane, the work can be performed without assembling a scaffold or the like.

  Then, by making the spiral reinforcing bar 82 protrude from the assembled reinforcing bars 83 for attaching the spiral reinforcing bar 82 to the wrapping column 8, the adjacent wrapping columns 8, 8 can be accurately viewed in plan view. Overlapping interlocking bars can be formed. That is, by this interlocking reinforcement, the restraining effect of the concrete 4 of the wall portion 11B is enhanced, and the deep foundation pile 1B having a high yield strength against a horizontal load such as seismic force can be obtained.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or Example 1, and thus description thereof is omitted.

  The best embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment and example, and the design does not depart from the gist of the present invention. Such modifications are included in the present invention.

  For example, in the said embodiment and Example, although the case where the deep foundation pile 1 was constructed | assembled as an underground structure was demonstrated, it is not limited to this, A caisson, a basement, etc. are constructed as an underground structure. It may be a thing.

  In addition, in the above-described embodiments and examples, the underground structure having a circular shape in plan view has been described. However, the present invention is not limited to this, and is not limited thereto. It can be constructed in an arbitrary shape such as a visual oval.

  Moreover, although the said embodiment demonstrated the case where the top plate 13 was constructed | assembled as a top part, it is not limited to this, The structure which bridges a beam between the upper ends of the wall part 11 as a top part may be sufficient.

  Further, the hollow portion 14 of the above embodiment may be used for processing of excavated residual soil such as backfilling with excavated soil generated when the excavation hole 5 is excavated. Moreover, although the said embodiment and the Example demonstrated the case where the inside was made hollow by making the trunk | drum part into the wall part 11, it is not limited to this, The solid which fills all the excavation holes 5 with concrete It may be a columnar body.

  Moreover, in the said embodiment and Example, although the steel rebar member which has arrange | positioned the helical reinforcement 22 and 82 of planar view substantially rectangular shape was demonstrated, it is not limited to this, Plane view substantially circular, substantially square, substantially Various shapes of spiral reinforcing bars such as diamonds can be arranged.

  Furthermore, in the said Example 1, 2, although the case where H-shaped steel was arrange | positioned as a steel frame of a steel frame reinforcement member was demonstrated, it is not limited to this, A steel pipe and other shape steel like the said embodiment May be used as a steel frame.

It is the cutting perspective view showing the schematic structure of the deep foundation pile of the best embodiment of the present invention. It is a perspective view explaining the structure of a spiral column, Comprising: (a) is a figure at the time of arrange | positioning H-shaped steel as a steel frame, (b) is a figure at the time of arrange | positioning a steel pipe as a steel frame. It is sectional drawing which showed the structure of the wall part of the deep foundation pile of the best embodiment of this invention. It is process drawing explaining the construction method of the deep foundation pile of the best embodiment of this invention. (A) is sectional drawing which showed the structure of the wall part of the deep foundation pile of Example 1, (b) is the perspective view which showed the structure of the link reinforcement. It is sectional drawing which showed the structure of the wall part of the deep foundation pile of Example 2. FIG. 6 is a perspective view showing a configuration of a wrapping column of Example 2. FIG.

Explanation of symbols

1,1A, 1B Deep foundation pile (underground structure)
11, 11A, 11B Wall (torso)
12 Bottom plate 13 Top plate (top)
2,2A Spiral column (steel rebar member)
21 H-section steel (steel frame)
22 Spiral rebar 23 Assembly rebar 24 Steel pipe (steel frame)
3 Reinforcing bar 4 Concrete 50 Ground 5 Drilling hole 5a Hole wall 5b Bottom face 7 Link bar 8 Lapping column (steel rebar member)
81 H-section steel (steel frame)
82 Spiral Reinforcement 82a Protrusion 83 Assembly Rebar

Claims (6)

It is a construction method of an underground structure in which concrete is driven into a drilling hole formed by excavating the ground.
A plurality of steel rebar members having a steel frame and helical rebars arranged in a spiral around the steel frame are provided at intervals along the hole wall of the excavation hole so that the lower end of the steel rebar member is embedded. The construction method of the underground structure characterized in that concrete is placed on the bottom surface of the excavation hole and concrete is placed around the steel rebar member to construct the trunk portion. It is a construction method of an underground structure in which concrete is driven into a drilling hole formed by excavating the ground.
A plurality of band reinforcing bars extending along the hole wall of the excavation hole are arranged at intervals in the vertical direction, and a steel frame reinforcing bar member having a steel frame and a spiral reinforcing bar arranged in a spiral manner around the steel frame is provided. A plurality of reinforcing bars are set up at intervals along the inside of the reinforcing bar, and a plurality of strip reinforcing bars extending along the inside of the steel reinforcing bar member are arranged at intervals in the vertical direction, and the lower end of the steel reinforcing bar member is embedded. As shown, the concrete is placed on the bottom surface of the excavation hole to construct a bottom plate, and the wall is constructed by placing concrete around the steel rebar member and the belt reinforcing bar. The construction method of the underground structure characterized by constructing the top part which transmits the load from upper direction to the said wall part at an upper end part. It is a construction method of an underground structure in which concrete is driven into a drilling hole formed by excavating the ground.
A plurality of steel rebar members each having a steel frame and a helical rebar disposed in a spiral manner around the steel frame are provided at intervals along the hole wall of the excavation hole. The bottom of the excavation hole is constructed so that the lower end of the steel rebar member is buried, and a bottom plate is constructed, and the concrete is placed around the steel rebar member. A method for constructing an underground structure, comprising: constructing a wall portion and constructing a top portion for transmitting a load from above to the wall portion at an upper end portion of the wall portion. It is a construction method of an underground structure in which concrete is driven into a drilling hole formed by excavating the ground.
A steel rebar member having a steel frame and a helical rebar arranged in a spiral around the steel frame is erected along the hole wall of the excavation hole, and the same steel rebar member is adjacent to the helical rebar in plan view. Concrete is placed on the bottom surface of the excavation hole so that the lower ends of the steel rebar members erected in such a manner that the spiral rebars overlap each other in a plan view are embedded. Constructing a bottom plate, constructing a wall portion by placing concrete around the steel rebar member, and constructing a top portion for transmitting a load from above to the upper end portion of the wall portion. A method of constructing a characteristic underground structure. An underground structure built by digging concrete into an excavation hole formed by excavating the ground,
A steel rebar member having a steel frame, a plurality of rebars erected around it, and a spiral rebar member that spirally surrounds the outside of the rebars and protrudes outward from the rebars on both sides, is adjacent to the steel rebar member. The protruding portions of the steel rebar members of the steel rebar members are arranged so as to overlap each other in plan view, and the inside of the hole wall is surrounded by a plurality of steel rebar members, and concrete is placed around these steel rebar members. An underground structure characterized by that. The wall part formed in the cylinder shape by the concrete cast around the steel-steel rebar member, the bottom plate that closes the lower end side of the wall part, and the top plate that closes the upper end side of the wall part The underground structure according to claim 5.

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