JP7462908B2 - Pile head treatment structure and pile head treatment method - Google Patents

Description

This invention belongs to the technical field of pile head treatment structures and pile head treatment methods in which a plurality of anchor rebars are provided on the outer periphery of the head of a foundation pile (a concrete pile covered with a steel pipe, or a steel pipe pile) that has a steel pipe around the periphery of the pile head, for connecting to a foundation structure.

Conventionally, a well-known pile head treatment structure (construction method) for joining the head of a foundation pile to a foundation structure involves welding a plurality of anchor rebars to the outer peripheral surface of the head of the foundation pile and arranging the anchor rebars inside the foundation structure to join the pile to the foundation structure.
As shown in Patent Documents 1 and 2, the anchor reinforcing bars (also called pile head reinforcing bars) are often arranged at the pile head via a number of steel plates (or similar plate members with flat surfaces).

JP 2014-84573 A JP 2017-172310 A

However, the steel plates etc. used to fix the anchor rebar to the pile head have a flat surface, which means that the flat surface has weak adhesion to the concrete poured to build the foundation, resulting in a loss of integrity with the concrete. This problem is an issue that must be resolved, as it affects the strength, rigidity and soundness of the foundation and, ultimately, the entire structure.

The present invention was devised in consideration of the problems in the background technology described above, and its purpose is to provide a pile head treatment structure and pile head treatment method that can increase the adhesion strength with concrete, ensure integration with concrete, and provide excellent strength, rigidity, and soundness of the foundation structure and, ultimately, the entire structure.

As a means for solving the problems of the above-mentioned background art, the pile head treatment structure according to the invention described in claim 1 is a pile head treatment structure in which a plurality of anchor reinforcing bars for joining to a foundation structure are provided on the outer peripheral surface of the pile head of a foundation pile having a steel pipe on the outer periphery of the pile head,
The multiple anchor reinforcing bars are each integrated by stacking and welding deformed reinforcing bars, and the multiple anchor reinforcing bars are attached to the outer circumferential surface of the pile head of the foundation pile via the deformed reinforcing bars by welding the deformed reinforcing bars to the steel pipe (however, the deformed reinforcing bars do not include deformed steel bars with grooves) .

The invention described in claim 2 is characterized in that in the pile head treatment structure described in claim 1, the deformed bar interposed between the anchor reinforcing bar and the outer surface of the pile head of the foundation pile is a single deformed bar or a deformed bar formed by stacking and welding multiple bars together.

The invention described in claim 3 is characterized in that, in the pile head treatment structure described in claim 1 or 2, the anchor reinforcing bar integrated with the deformed reinforcing bar is a single anchor reinforcing bar or an anchor reinforcing bar formed by overlapping and welding a plurality of anchor reinforcing bars.
The invention described in claim 4 is characterized in that, in the pile head treatment structure described in any one of claims 1 to 3, a deformed steel bar is overlapped and welded to the head of the anchor steel bar.
The invention described in claim 5 is characterized in that, in the pile head treatment structure described in any one of claims 1 to 4, the welded portion of the anchor reinforcing bar to the deformed reinforcing bar is subjected to groove preparation by cutting the outer circumferential surface.
The invention described in claim 6 is characterized in that, in the pile head treatment structure described in any one of claims 1 to 5, the foundation pile is a steel pipe-coated concrete pile or a steel pipe pile.

The invention described in claim 7 is characterized in that in the pile head treatment structure described in any one of claims 1 to 6, the anchor rebars are arranged in a total of 8 at the portions of the pile head that correspond to the vertices of a regular octagon, or in a total of 10 at the portions of the pile head that correspond to the vertices of a regular decagon, or in a total of 12 at the portions of the pile head that correspond to the vertices of a regular dodecagon.

The pile head treatment method according to the invention described in claim 8 is a pile head treatment method in which a plurality of anchor reinforcing bars for joining to a foundation structure are provided on the outer peripheral surface of the pile head of a foundation pile having a steel pipe on the outer periphery of the pile head,
The multiple anchor reinforcing bars are each formed into an integrated unit by overlapping and welding deformed reinforcing bars, and each of the deformed reinforcing bars of the unit is welded to the outer periphery of the head of a foundation pile installed in the ground, so that the multiple anchor reinforcing bars are installed on the outer periphery of the head of the foundation pile via the deformed reinforcing bars (however, the deformed reinforcing bars do not include deformed steel bars with grooves) .

(1) According to the pile head treatment structure and pile head treatment method of the present invention, a plurality of anchor reinforcing bars are each integrated into a unit by overlapping and welding deformed reinforcing bars, and the deformed reinforcing bars of the unit are each welded to the outer periphery of the pile head of a foundation pile installed in the ground, so that the plurality of anchor reinforcing bars are installed on the outer periphery of the pile head of the foundation pile via the deformed reinforcing bars. Since the deformed reinforcing bars are used as connecting members connecting the anchor reinforcing bars and the pile head, the connecting members can be sufficiently enhanced in adhesion strength with the concrete, and can be reliably integrated with the concrete, thereby realizing a true reinforced concrete structure (RC structure). Therefore, a pile head treatment structure and pile head treatment method excellent in strength, rigidity, and soundness of the foundation structure and the entire structure, as well as reliability, can be realized.
(2) As shown in Figures 5 to 7, when the deformed bar is welded to the head of the anchor bar (the invention described in claim 4), the adhesion area with the concrete increases, so the adhesion strength with the foundation structure can be increased, and the deformed bar can be expected to have an anchoring effect, so that the foundation structure and the entire structure can be provided with excellent strength, rigidity, and soundness, as well as reliability, to realize a pile head treatment structure and pile head treatment method. In addition, the length of the anchor bar can be shortened, making it economical.

FIG. 1A is an elevation view showing an embodiment of a pile head treatment structure and a pile head treatment method according to the present invention, and FIG. 1B is a plan view of the same. Note that the welded portions 3 and 4 are slightly exaggerated in FIG. 1A and omitted in FIG. 1B for convenience of illustration. FIG. 1A is an elevation view showing a schematic diagram of a pile head treatment structure and a pile head treatment method according to another embodiment of the present invention, and FIG. 1B is a plan view of the same. Note that the welded portions 3 and 4 are slightly exaggerated in FIG. 1A and omitted in FIG. 1B for convenience of illustration. FIG. 2 is a plan view showing a schematic diagram of a pile head treatment structure and a pile head treatment method according to a different embodiment of the present invention. FIG. 1A is an elevation view showing a schematic diagram of a pile head treatment structure and a pile head treatment method according to another embodiment of the present invention, and FIG. 1B is a plan view of the same. Note that the welded portions 3 and 4 are slightly exaggerated in FIG. 1A and omitted in FIG. 1B for convenience of illustration. FIG. 2 is an elevation view showing a schematic diagram of a pile head treatment structure and a pile head treatment method according to another embodiment of the present invention. FIG. 2 is an elevation view showing a schematic diagram of a pile head treatment structure and a pile head treatment method according to another embodiment of the present invention. FIG. 2 is an elevation view showing a schematic diagram of a pile head treatment structure and a pile head treatment method according to another embodiment of the present invention. A is a vertical cross-sectional view showing an example of a foundation pile to which the pile head treatment structure and pile head treatment method of the present invention can be applied, B is a cross-sectional view taken along line B-B of A, and C is a plan view of A. A is a vertical cross-sectional view showing an example of a foundation pile to which the pile head treatment structure and pile head treatment method of the present invention can be applied, B is a cross-sectional view taken along line B-B of A, and C is a plan view of A.

Next, an embodiment of the pile head treatment structure and pile head treatment method according to the present invention will be described with reference to the drawings.

The pile head treatment structure of the present invention, as illustrated in Figures 1 to 3, is a pile head treatment structure in which a plurality of anchor reinforcing bars 1 for joining to a foundation structure 11 are provided on the outer peripheral surface of the pile head of a foundation pile 10 having a steel pipe 10a around the outer periphery of the pile head, and the plurality of anchor reinforcing bars 1 are each integrated by overlapping and welding 3 a deformed reinforcing bar 2, and the plurality of anchor reinforcing bars 1 are provided on the outer peripheral surface of the pile head of the foundation pile 10 via the deformed reinforcing bars 2 by welding 4 the deformed reinforcing bars 2 to the steel pipe 10a (however, the deformed reinforcing bars do not include grooved deformed steel bars) .

The foundation pile 10 having a steel pipe 10a on the outer periphery of the pile head means a foundation pile 10 having a steel pipe 10a at least on the outer periphery of the pile head (exposed pile head portion), and naturally includes steel-pipe-coated concrete piles such as SC piles in which the steel pipe 10a is coated over the entire length of the pile, or steel pipe piles, or piles in which the steel pipe 10a is attached externally to cast-in-place concrete.
Incidentally, the foundation pile 10 in Figures 1 and 2 shows an embodiment in which the SC pile 10 is applied. Instead of the SC pile 10, a steel pipe covered concrete pile 10 developed by the present applicant as shown in Figures 8 and 9 can be used in the same manner. The configuration of the steel pipe covered concrete pile 10 in Figures 8 and 9 will be described later.

In this embodiment, as shown in FIG. 1B, a total of eight anchor rebars 1 are placed at the pile head at the vertices of a regular octagon, but the number of rebars used is of course not limited to this and can be increased or decreased as appropriate depending on the structural design. For example, it is also possible to place a total of ten rebars at the vertices of a regular decagon, or a total of twelve rebars at the vertices of a regular dodecagon.

In this embodiment, the deformed reinforcing bar 2 has approximately the same diameter as the anchor reinforcing bar 1 .
Here, to give examples of the sizes of the components used in the present invention, the foundation pile (SC pile) 1 has a pile diameter of about 300 to 1000 mm, a length of about 5 to 15 m, and a steel pipe thickness of about 4.5 to 19 mm. The anchor rebar 1 has a diameter (φ) of about 25 to 35 mm, and its length is appropriately changed depending on the structural design. The deformed rebar 2 has a diameter (φ) of about 25 to 35 mm, and its length is shorter than that of the anchor rebar 1, for example, about 1/4 of the length.

In this embodiment, flare welding is used as the means 3 for overlapping and welding the anchor rebar 1 and the deformed rebar 2 (their outer peripheral surfaces). The welding length is preferably set to four times or more the diameter (φ) of the deformed rebar 2. Similarly, in this embodiment, flare welding is used as the means 4 for overlapping and welding the deformed rebar 2 and the steel pipe 10a. The welding length is preferably set to four times or more the diameter (φ) of the deformed rebar 2.
The welding means 3, 4 are not limited to flare welding means, and any welding means can be used as long as the required strength and rigidity can be reliably exhibited.

The procedure of the pile head treatment method according to the present invention is to first drive the foundation pile 10 into the ground 12 and expose the pile head of the foundation pile 10. The foundation pile 10 may be a prefabricated pile or a cast-in-place pile, so long as it is a foundation pile 10 with a steel pipe 10a on the outside. The anchor rebar 1 is previously integrated with the deformed rebar 2 by flare welding means 3 or the like in a factory or the like to form a unit in the number of pieces to be used.
Next, when preparations such as removing the black skin on the surface of the steel pipe 10a at the pile head by sandblasting are completed as necessary, the deformed rebar 2 of the unitized anchor rebar 1 and deformed rebar 2 is positioned on a predetermined outer circumferential surface of the steel pipe 10a at the pile head of the foundation pile 10 and integrated by welding using a flare welding means 4 or the like. Thus, the unitized anchor rebars 1 (eight in the illustrated example) are arranged in a well-balanced manner on the outer circumferential surface of the pile head 10a of the foundation pile 10 via the deformed rebars 2.
It should be noted that the above-described procedure is merely an example.

In the case of the embodiment shown in Fig. 2, one anchor rebar 1 and two of the deformed rebars 2, 2 are previously unitized at a factory or the like by integrating them at the overlapping abutment portions with flare welding means 3. In the case of the embodiment shown in Fig. 2 as well, at the site, one of the unitized anchor rebar 1 and two deformed rebars 2, 2 is positioned on a predetermined outer circumferential surface of the steel pipe 10a at the head portion of the foundation pile 10 and welded to one another with flare welding means 4 or the like.
That is, according to this embodiment, the work at the site is the same as in the embodiment of Fig. 1 in that one deformed bar 2 is positioned on a predetermined outer peripheral surface of the steel pipe 10a at the pile head of the foundation pile 10 and welded to one piece by flare welding means 4 or the like. Therefore, it can be realized in the same construction period as the embodiment of Fig. 1. However, if a plurality of deformed bars 2 (two in the illustrated example) are overlapped and welded, the virtual reinforced concrete cross section D of the pile head (foundation pile 10) can be increased according to the number of deformed bars 2, so that the rigidity (bending resistance) and strength of the pile head (foundation pile 10) can be increased.
In the illustrated example, two deformed bars 2 are overlapped and welded, but the present invention is not limited to this, and although not shown, three or more deformed bars can be overlapped and welded together. When implemented in this manner, not only can the virtual reinforced concrete cross section D be enlarged, but the width and shape of the deformed bars 2 that serve as the ties (connecting members) between the anchor bars 1 and the pile heads can be freely changed, which has the advantage of allowing flexible reinforcing bar arrangement, for example as shown in FIG. 3, without interference with the reinforcing bars arranged inside the foundation structure 11.

In the case of the embodiment shown in Fig. 4, the two anchor rebars 1, 1 and the one deformed rebar 2 are previously unitized at a factory or the like by integrating them at the abutting portions where they are overlapped with each other using flare welding means 3. In the case of the embodiment shown in Fig. 4 as well, at the site, of the two anchor rebars 1, 1 and the one deformed rebar 2 that have been unitized, one deformed rebar 2 is positioned on a predetermined outer circumferential surface of the steel pipe 10a at the head portion of the foundation pile 10, and is welded and integrated using flare welding means 4 or the like.
That is, according to this embodiment, the on-site work is the same as in the embodiment shown in Fig. 1 in that one deformed rebar 2 is positioned on a predetermined outer circumferential surface of the steel pipe 10a at the pile head of the foundation pile 10 and integrated by welding using a flare welding means 4 or the like. Therefore, it can be realized in the same construction period as the embodiment shown in Fig. 1. However, when a plurality of anchor rebars 1 (two in the illustrated example) are overlapped and welded, the pile head (foundation pile 10) can have an increased number of anchor rebars 1, thereby increasing the strength and rigidity of the foundation structure 11 and the entire structure.
In the illustrated example, two anchor rebars 1 are overlapped and welded together, but the present invention is not limited to this. Although not shown in the drawings, three or more anchor rebars can also be overlapped and welded together.

Therefore, the pile head treatment structure and pile head treatment method according to the present invention have the following effects.
A plurality of anchor reinforcing bars 1 are formed into an integrated unit by overlapping and welding deformed reinforcing bars 2, and the deformed reinforcing bars 2 of the unit are respectively welded to the outer peripheral surface of the head of a foundation pile 10 installed in the ground, so that the plurality of anchor reinforcing bars 1 are installed via the deformed reinforcing bars 2 on the outer peripheral surface of the head of the foundation pile 10. Since the deformed reinforcing bars 2 are used as connecting members connecting the anchor reinforcing bars 1 to the pile head, the adhesive strength of the connecting members (deformed reinforcing bars 2) with the concrete can be sufficiently increased and the connecting members can be reliably integrated with the concrete, thereby realizing a true reinforced concrete structure (RC structure).
Therefore, it is possible to realize a pile head treatment structure and pile head treatment method that have excellent strength, rigidity, and soundness, as well as reliability, of the foundation structure 11 and, by extension, the entire structure.
In addition, if multiple deformed bars 2 used as the connecting members are lap-welded to appropriately lengthen the length (width) of the connecting members (see Figures 2 and 3), the virtual reinforced concrete cross-section D of the pile head (foundation pile 10) can be increased according to the number of deformed bars 2, thereby increasing the rigidity (bending resistance) and strength of the pile head (foundation pile 10).
In addition, since the length of the anchor rebar 1 is sufficiently long, it is possible to fully connect it to the rebar to be placed on the outside by a lap joint, and the labor required for subsequent welding work can be eliminated.

(Supplementary explanation regarding the structure of foundation piles)
As mentioned in the last sentence of the above paragraph [0015], next, the configuration of the steel pipe covered concrete pile 10 shown in Figures 8 and 9 will be described.
Figures 8 and 9 show the foundation pile 10 developed by the applicant. The foundation pile 10 shown in Figures 1 to 4 is an example assuming the SC pile 10, but the foundation pile 10 developed by the applicant can be used in place of the SC pile 10 in the same manner.
The foundation pile 10 developed by the applicant is a steel pipe covered concrete pile (steel pipe covered high strength concrete pile) called an SPHC pile (SPHC is a registered trademark of the applicant), and is integrally composed of a PHC pile 10b, a steel pipe 10a arranged concentrically around the periphery of the PHC pile 10b with a gap, and a filler material 10c filled in the gap. Incidentally, the reference numeral 10d in the figure indicates the end plate of the PHC pile 10b.
The steel pipe 10a of the SPHC pile 10 is configured so that its upper end is connected to the foundation of the foundation structure 11 so as to be capable of transmitting horizontal force, and is shorter in length than the PHC pile 10b. As the filler 10c, cement milk is preferably mainly used.
8 and 9 are different in that the steel pipe 10a in FIG. 8 is a hollow cylinder, whereas the steel pipe 10a in FIG. 9 is a cylinder with a bottom, but the other configurations are similar.
Therefore, the SPHC pile (steel pipe covered concrete pile) 10 developed by the present applicant has the same configuration as the SC pile 10, which has a steel pipe 10a on the outside. Therefore, it can be implemented in the same manner as the above-mentioned embodiment (see Figs. 1 to 4), and has the same effects.

Although the above describes the embodiments based on the drawings, it should be noted that the present invention is not limited to the illustrated examples, and includes the range of design modifications and application variations that would normally be made by a person skilled in the art, provided that the scope does not deviate from the technical concept.

For example, as shown in Figs. 5 to 7, a deformed bar 2 may be overlapped and welded to the head of the anchor bar 1.
According to these embodiments, the adhesion area with the concrete is increased, so that the adhesion strength with the foundation structure 11 can be further increased, and the deformed reinforcing bar 2 can be expected to have an anchoring effect, so that a pile head treatment structure and pile head treatment method that are extremely excellent in the strength, rigidity, soundness, and reliability of the foundation structure 11 and, in turn, the entire structure can be realized. In addition, the length of the anchor reinforcing bar 1 can be shortened, and so the method is also economical (for example, see FIG. 1A and FIG. 5).

In addition, in order to increase the reliability and ease of the welding work, appropriate measures such as cutting the outer surface of the anchor rebar 1 and preparing a groove at the welded portion with the deformed rebar 2 are taken.

1 Anchor rebar 2 Deformed rebar 3 Welding (welding method)
4. Welding (welding method)
10 Foundation pile 10a Steel pipe 11 Foundation structure 12 Ground D Virtual reinforced concrete cross section

Claims (8)

A pile head processing structure in which a plurality of anchor reinforcing bars for joining to a foundation structure are provided on the outer peripheral surface of a foundation pile having a steel pipe on the outer periphery of the pile head,
The pile head treatment structure is characterized in that each of the multiple anchor reinforcing bars is integrated by stacking and welding deformed reinforcing bars , and the multiple anchor reinforcing bars are attached to the outer circumferential surface of the pile head of the foundation pile via the deformed reinforcing bars by welding the deformed reinforcing bars to the steel pipe (however, the deformed reinforcing bars do not include deformed steel bars with grooves) . The pile head treatment structure described in claim 1, characterized in that the deformed bar interposed between the anchor bar and the outer surface of the pile head of the foundation pile is a single deformed bar or a deformed bar formed by stacking and welding multiple bars. The pile head treatment structure described in claim 1 or 2, characterized in that the anchor reinforcing bar integrated with the deformed reinforcing bar is a single anchor reinforcing bar or an anchor reinforcing bar formed by stacking and welding multiple anchor reinforcing bars. The pile head treatment structure described in any one of claims 1 to 3, characterized in that a deformed reinforcing bar is overlapped and welded to the head of the anchor reinforcing bar. The pile head treatment structure described in any one of claims 1 to 4, characterized in that the welded portion of the anchor reinforcing bar to the deformed reinforcing bar is subjected to groove preparation by cutting the outer periphery. The pile head treatment structure described in any one of claims 1 to 5, characterized in that the foundation pile is a steel pipe covered concrete pile or a steel pipe pile. The pile head treatment structure described in any one of claims 1 to 6, characterized in that the anchor rebars are arranged in a total of eight at the portions corresponding to the vertices of a regular octagon, or in a total of ten at the portions corresponding to the vertices of a regular decagon, or in a total of twelve at the portions corresponding to the vertices of a regular dodecagon, on the pile head. A pile head processing method in which a plurality of anchor rebars for joining to a foundation structure are provided on the outer peripheral surface of a foundation pile having a steel pipe on the outer periphery of the pile head,
This pile head treatment method is characterized in that each of the multiple anchor reinforcing bars is formed into an integrated unit by overlapping and welding deformed reinforcing bars, and each of the deformed reinforcing bars of the unit is welded to the outer periphery of the pile head of a foundation pile installed in the ground, thereby installing the multiple anchor reinforcing bars via the deformed reinforcing bars on the outer periphery of the pile head of the foundation pile (however, the deformed reinforcing bars do not include deformed steel bars with grooves) .

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