JP2021080677A - Pile foundation structure - Google Patents

Abstract

To integrally join a pile head part of a pile body and a structural part of a pile foundation together in foundation structures of various structures supported by pile bodies.SOLUTION: A pile foundation structure comprises a pile 1 with a pile head 2 protruding from the ground surface for a predetermined length, a foundation beam 15 joined to the pile head 2, a pile head joint pipe 20 whose internal space 22 is of a circular shape when viewed in a plan view, which is installed on the ground surface so that the pile head 2 is located approximately in the center of the internal space 22 and supports the pile head 2 by having the internal space 22 filled with infilling concrete 23, and a precast joint body 30 which is installed on a ground surface 5a and holds a main bar joint bar 35 to be joined to the end of a main bar 17 of the foundation beam 15. The foundation beam 15 is installed with a predetermined separation part from the outer peripheral surface of the precast joint 30, the main bar 17 of the foundation beam 15 and the main bar joint bar 35 are joined, integrated with the precast joint body 30 via joint concrete 46, and constructed by overlapping the pile head joint pipe 20 vertically and joined with the pile head 2.SELECTED DRAWING: Figure 3

Description

The present invention relates to a pile foundation structure, and relates to a pile foundation structure capable of integrally joining a pile head of a pile body and a structural portion of the pile foundation in the foundation structure of various structures supported by the pile body.

In the joint structure between the pile head of the pile body and the structural parts such as the foundation beam and foundation footing of the reinforced concrete structure, the pile head and the structural part of the pile foundation are integrated so that a predetermined strength and rigidity are secured. A large number of reinforcing bars are arranged in a space having a narrow joint structure, and labor-intensive and complicated reinforcement work is required.

In order to solve this problem, a foundation structure having increased rigidity between the pile head and the foundation footing is disclosed (Patent Document 1). In this foundation structure, a predetermined space (pile head insertion portion) is secured at the outer peripheral position of the pile head, a lower precast foundation member is installed, and a predetermined stress transmission member is provided at the pile head insertion portion in the space. By filling the filler, the pile head and the lower precast foundation member are integrated.

The lower precast foundation member disclosed in Patent Document 1 is a large precast concrete member set to have a sufficient horizontal cross-sectional area and burial depth to be integrated with the footing member constructed on the lower precast foundation member. There is. The production of this precast concrete member and the work of carrying it in and installing it at the site are large-scale work. Further, since the joining of the column and the foundation beam erected on the lower precast foundation member and the construction of the footing member are all on-site work, a complicated work process is required.

On the other hand, as a basic structure for reducing the work process in the field, the basic structure disclosed in Patent Document 2 has been proposed. This foundation structure consists of a structure in which a round-cut steel pipe installed at the pile head and a joint structure are integrated. The round-cut steel pipe located at the bottom of the foundation structure is installed so as to surround the pile head of the pile body, and the pile head is fixedly held by the concrete filled inside. The footing as a joint structure at the upper part of the foundation structure has a joint with the foundation beam, supports the column base of the erected column, and structurally joins the end of the foundation beam and the column.

Japanese Unexamined Patent Publication No. 2016-70028 JP-A-2017-137711

Since the foundation structure disclosed in Patent Document 2 is a large-scale structure in which a round-cut steel pipe and a steel pipe or a precast concrete cylinder constituting the footing of the joint structure are integrally constructed, it is carried into the site. However, there is a problem that the installation work becomes large-scale and the work efficiency is poor.
Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional techniques, to provide a pile head joint pipe made of a steel pipe concrete composite structure that firmly supports the pile head, and a pile such as a foundation beam or foundation footing in advance. A precast concrete precast joint with a built-in joint reinforcement and the structural reinforcement of the structural part of the foundation are integrally stacked and constructed to facilitate the structural connection between the foundation beam and the pile head. The purpose is to provide a pile foundation structure that can be reliably performed and that can save labor and labor.

In order to achieve the above object, in the pile foundation structure of the present invention, a pile having a pile head protruding from the ground surface for a predetermined length, a structural portion of the pile foundation joined to the pile head, and an internal space are flat. It has an annular shape when viewed, and is installed on the ground surface of the ground so that the pile head is located approximately in the center of the internal space, and the internal space is filled with filled concrete to support the pile head. Precast that holds the pile head joint pipe to be used and the main bar joint bar that is installed on the backfilled ground surface around the pile head joint pipe and is jointly joined to the main bar end of the structural part of the pile foundation. A joint body is provided, and the structural portion of the pile foundation is installed with a predetermined separation portion from the outer peripheral surface of the precast joint body, and the main bar end of the structural portion of the pile foundation and the main bar joint bar are joined. It is characterized in that it is integrated with the precast joint body via the joint concrete in the state of being piled up, and is constructed so as to be vertically overlapped with the pile head joint pipe and joined with the pile head.

The pile head joint pipe is preferably a precast reinforced concrete member having a steel pipe concrete composite structure composed of an outer skin steel pipe and an inner peripheral concrete portion.

In the pile head joint pipe, it is preferable to arrange joint vertical bars in the inner peripheral concrete portion.

The precast joint includes a pile head connecting portion that can be loosely fitted in the internal space of the pile head joining pipe, and a lower joint portion including the main reinforcing bar that is joined to the main bar end of the structural portion of the pile foundation. It is preferable that the precast reinforced concrete member is composed of an upper joint portion on which a pillar erected on the upper surface can be placed.

The precast joint preferably holds the column main muscle joint muscles to be joined to the main muscles of the column in addition to the main muscle joint muscles.

In the precast joint body, a through hole through which a joint vertical streak erected in the pile head joint pipe can be inserted is formed, and the joint vertical streak is held in the through hole to form a through hole with the pile head joint pipe. It is preferable that they are integrated.

The structural portion of the pile foundation is preferably a reinforced concrete foundation beam or foundation footing.

The plan view and the side view which showed the appearance shape of one Embodiment of the pile foundation structure of this invention. FIG. 5 is a plan sectional view showing an example of internal configurations of a precast joint and a beam joint along the II-II cross-sectional line of the pile foundation structure shown in FIG. 1 (b). A side sectional view showing an example of internal configurations of a precast joint and a beam joint along the III-III cross-sectional line of the pile foundation structure shown in FIG. 1 (a). A plan view and a side sectional view of a pile head joint pipe constituting the pile foundation structure of the present invention. A plan sectional view (FIG. 3VV sectional line) showing a fixed state of the pile head by the pile head joint pipe. The plan view which showed the plan shape of the precast joint. A side view and a side sectional view showing the side shape and the bar arrangement state of the precast joint. Explanatory drawing which showed the construction procedure of the pile foundation structure of this invention (the 1: (a)-(c)). Explanatory drawing which showed construction procedure of pile foundation structure of this invention (part 2: (d), (e)). Explanatory drawing which showed construction procedure of pile foundation structure of this invention (part 3: (f), (g)). A side sectional view showing a joint state (integrally fixed) between a pile head joint pipe and a precast joint. A side sectional view showing a joint state (semi-fixed) between a pile head joint pipe and a precast joint.

Hereinafter, the configuration of the pile foundation structure of the present invention will be described with reference to the accompanying drawings. FIG. 1 Each figure shows, as an embodiment of the pile foundation structure 10 of the present invention, a pile foundation structure 10 in which a foundation beam 15 arranged vertically and horizontally in a plan view and a pile head 2 of a pile body 1 are joined. A part of the external shape is shown. As shown in FIG. 1B, the pile foundation structure 10 of the present invention includes a pile head joint pipe 20 constituting a pile cap covering the pile head 2 of the pile body 1 and a pile head joint pipe 20. Mainly a precast joint body 30 made of precast reinforced concrete having a predetermined shape, which is structurally integrally joined to the upper surface and joins the foundation beam 15 and the pile head joint pipe 20 as one aspect of the structural part of the pile foundation. It is configured. On the side surface of the precast joint body 30, four foundation beams 15 arranged vertically and horizontally in a cross shape in a plan view (FIG. 1 (a)) are joined via a joint concrete 46. The planar shape of the precast joint 30 has a substantially octagonal shape in which sides equal to the beam width of the foundation beam 15 are connected by haunch-shaped hypotenuses. A precast concrete column (1,000 mm □) 40 having a square flat cross section is erected on the top surface of the substantially octagonal precast joint 30 at the center of the upper surface (FIG. 1 (b)).

The pile body 1 of the present embodiment is made of a ready-made pile having a pile outer diameter of 1,000 mmφ, for example, a concrete pile with an outer shell steel pipe. The pile head 2 of the pile body 1 is filled with filled concrete (not shown) and stiffened. As shown in FIGS. 1B and 3, the ground on which the pile head 2 is located is excavated about 1 m below the original ground surface 5a, and the pile head 2 of the pile body 1 is lowered. The pile head joint pipe 20 is in a state of protruding from 5b for a predetermined length, and is placed on the leveling concrete 7 laid on the ground surface 5b under the ground so as to surround the pile head 2.

The foundation beam 15 of the present embodiment is made of a precast reinforced concrete member having a beam length of 2,000 mm and a beam width of 1,000 mm, so that the pile head 2 is an intersection of the beams as shown in each figure of FIG. Around the installed precast joint 30, the predetermined separated portion 16 is taken and arranged vertically and horizontally so as to form a cross in a plan view, and placed on the leveled concrete 6 laid on the ground surface 5a. It is structurally rigidly joined to each side surface of the precast joint 30 via the cast concrete 46.

The configuration of the pile head joint pipe 20 of the present embodiment will be described with reference to each figure of FIG. The pile head joint pipe 20 is placed on the ground surface 5b (FIG. 1 (b)) lowered so as to cover the side portion of the pile head 2 of the pile body 1, and is mounted on the precast joint body 30 described later. It is a main constituent member for joining the pile head 2 of the pile body 1. As shown in FIGS. 4A and 4B, the pile head joint pipe 20 is formed of a cylindrical body having a circular internal space 22 in a plan view. This cylindrical body is a precast concrete member having a steel pipe concrete composite structure in which an inner peripheral concrete 24 having a predetermined thickness is integrally formed on the inner peripheral surface of the outer skin steel pipe 21. The dimensions of the outer skin steel pipe 21 of the present embodiment are a diameter (outer diameter) of 1,700 mmφ, a height of 1,150 mm, and a plate thickness of 16 mm. In order to integrate the outer skin steel pipe 21 and the inner peripheral concrete 24, it is preferable to dispose various jibels and studs (not shown) on the inner surface of the outer skin steel pipe 21. The diameter of the internal space 22 of the pile head joint pipe 20 is set in consideration of the construction error of the pile position where the pile head is placed. For example, the diameter of the internal space 22 should be set to 15% or more of the outer diameter of the pile, and a predetermined clearance should be provided. The foundation beam 15 can be installed with high accuracy.

As shown in FIGS. 4 (a) and 4 (b), the inner peripheral concrete 24 of the pile head joint pipe 20 is provided with a beam joining direction (X, Y directions in FIG. 4 (a)) at 45 °. Six vertical bars 25 are arranged at such positions so as to project from the upper surface of the inner peripheral concrete 24. The bar arrangement position of the vertical bar 25 corresponds to the through hole 39 formed in the haunch portion (described later) of the precast joint 30 shown in FIG. 6, and the precast joint 30 is placed on the pile head joint pipe 20. When placed, each vertical bar 25 is inserted into each through hole 39, a solidifying material (not shown) is filled in the through hole 39, and the precast joint body 30 and the pile head joint pipe 20 are integrated. It becomes a reinforcing joint muscle to make. As shown in FIGS. 2 and 5, a filling concrete 23 is placed in the gap (internal space 22) between the pile head joint pipe 20 (FIG. 4 (a)) and the pile head 2. The pile head joint pipe 20 and the pile head 2 are integrated.

The constituent members of the precast joint body 30 integrally joined to the upper part of the pile head joint pipe 20 will be described with reference to FIGS. 6 and 7. The precast joint body 30 is composed of a precast reinforced concrete member in which the joint reinforcing bars to be joined to the reinforcing bars of the beam and the column to be joined are arranged so as to protrude from the concrete skeleton.

As shown in FIGS. 6 and 7 (a), the precast joint 30 has two upper and lower stages of a beam joint 31 having a substantially octagonal shape in a plan view and a column joint 32 having a square shape equal to the column cross section. It is a precast reinforced concrete structure consisting of an integral structure of. In the present embodiment, the beam joint portion 31 is a haunch in which four corners other than the joint portion of the above-mentioned underground beam having a beam width of 1,000 mm, which is connected to a square side surface having a side of 1,500 mm, are cut out at a side of 250 mm. It has a substantially octagonal planar shape having a portion 31a, and has a height of about 950 mm. The column joint 32 is equal to a square column cross section having a side of 1,000 mm in a plan view, and has a height of about 600 mm. The precast joint 30 is provided with predetermined structural bars and assembly bars (not shown) so as to form a reinforced concrete structure having a predetermined strength and strength as a beam column joint.

In the precast joint body 30, as shown in each of FIGS. 6 and 7, the beam main bar 17 of the foundation beam 15 (FIGS. 3 and 4) is joined to and fixed to the pile foundation portion, and the beam main bar joint bar 35 (35A) , 35B) are arranged. Six beam main bar joint bars 35 are arranged as two-stage bar arrangements in the beam width direction according to the joint positions of the four foundation beams 15, and are arranged in the vertical and horizontal directions in a plan view. The upper beam main bar joint bar 35A is located at a substantially central position in the height direction of the column joint 32 of the precast joint 30 corresponding to the bar arrangement position of the upper beam main bar 17A of the foundation beam 15, and has a predetermined length from the side surface of the column joint 32. Reinforcement is arranged so that only it protrudes. The beam main bar joint bar 35B is arranged so that a predetermined length protrudes from the lower side surface near the lower end in the height direction of the lower part of the precast joint body 30 corresponding to the bar arrangement position of the lower beam main bar 17B of the foundation beam 15. There is.

Further, as shown in FIG. 7B, the column main muscle joint muscles 36 are arranged with the intersections of the beam main muscle joint muscles 35 (35A, 35B) arranged vertically and horizontally as guides. As shown in FIG. 7A, the upper end of the column main bar joint muscle 36 protrudes from the upper surface of the column joint portion 32 of the precast joint 30 by a predetermined length and is placed on the upper surface of the precast joint 30. It is joined to the lower end of the column main bar 43 of the concrete column 40 corresponding to the floor column via a mechanical joint 42 (FIG. 3). Further, in order to maintain the bar arrangement position of the column main muscle joint muscle 36 which is arranged at a position corresponding to the corner portion of the column 40, the hoop muscle 37 having a □ shape in a plan view forms the column main muscle joint muscle 36. Reinforcements are arranged at predetermined intervals in the column height direction so as to surround the columns. Further, in order to reinforce the vertical bar 25 which is the reinforcing joint bar with the precast joint body 30 in the beam joint portion 31, a plurality of substantially octagonal hoop bars 29 are arranged at predetermined intervals in the height direction. It is muscular.

Further, as shown in FIG. 7A, a pile head connecting portion 38 is formed on the bottom surface of the precast joint 30. The pile head connecting portion 38 has a flat cylindrical shape having a diameter slightly smaller than the diameter of the internal space 22 of the pile head joining pipe 20 shown in each drawing of FIG. 4, and the precast joint 30 is a pile head joining pipe. When placed on the 20th, it is fitted into the internal space 22 so as to cover the inner filling concrete 23 placed around the pile head 2 of the pile body 1 and the upper surface of the pile body 1 (FIG. 3). , The clearance (gap) with the pile head 2 is filled with the solidifying material 50 (FIG. 11), and the precast joint 30 and the pile head joint pipe 20 are integrated.

The precast joint body 30 described above is manufactured in a state where the end portion of the beam main bar joint bar 35 of each part protrudes from the side surface of the precast joint body 30, as shown in FIGS. Is set based on the size of the loading platform of the vehicle that can be mounted on the vehicle. If there is no dimensional restriction during transportation, it can be made larger than the above dimensions.

Hereinafter, the pile head joint pipe 20 and the precast joint 30 made of the steel pipe concrete composite structure described above are vertically stacked and integrally constructed, and the structural portion of the pile foundation is joined to the pile head 2 of the pile body 1. The internal configuration of the pile foundation structure 10 of the present invention as described above will be described with reference to FIGS. 2 and 3. FIG. 2 shows an example of the internal configuration of the precast joint 30 of the pile foundation structure 10 and the beam joint with the foundation beam 15, and FIG. 3 shows the pile head joint pipe 20, the precast joint 30, the concrete column 40, and the foundation. An example of the internal configuration of the beam joint with the beam 15 is shown.

As shown in FIG. 3, the pile head joining pipe 20 is installed on the ground surface 5b so as to surround the pile head 2 of the pile body 1 protruding from the lowered ground surface 5b, and has an internal space 22. The filling concrete 23 filled in the gap between the pile body 1 and the pile body 1 is integrated with the pile head 2 of the pile body 1. The surrounding ground 5c of the pile head joint pipe 20 is backfilled to the installation level of the foundation beam 15 as a structural part of the pile foundation, and the precast joint 30 (for example, FIG. 7A) is placed on the leveled ground surface 5a. Is placed. At this time, the vertical bar 25, which is a reinforcing joint bar with the precast joint body 30 erected in the pile head joint pipe 20, is inserted into the through hole 39 (FIG. 6) formed in the precast joint body 30 and penetrates. Together with the hoop bars 29 pre-arranged in the precast joint 30 by the solidifying material 50 filled in the holes 39, it functions to integrate the precast joint 30 and the pile head joint pipe 20.

A foundation beam 15 is joined to the side surface of the precast joint 30 via a joint concrete 46. The foundation beam 15 is placed on the leveling concrete 6 laid on the backfilled and leveled ground surface 5a, and the beam main bar 17 is placed via the beam main bar joint bar 35 of the precast joint 30 and the mechanical joint 18. The joint concrete 46, which is joined and connects the separated portion 16 between the precast joint 30 and the end face of the foundation beam 15, is cast as cast-in-place concrete and is joined to the precast joint 30.

As a result, the pile head 2, the pile head joint pipe 20, the precast joint 30, and the foundation beam 15 main body of the pile 1 are integrally constructed and joined, and rigid joining of each member of the pile foundation structure 10 is realized. There is. The concrete strength of the joint concrete 46 ^{is set to about 27 N / mm 2,} and the concrete strength of the joint concrete 46 is the same as the concrete strength of the filling concrete 23 cast in the field, which is the design condition of the pile foundation structure 10. It is preferable to set as appropriate.

Hereinafter, the construction procedure for constructing the pile foundation structure 10 of the present invention will be described with reference to FIGS. 8 (a) to 8 (c), FIGS. 9 (d) and 9 (e), and FIGS. 10 (f) and 10 (g). ..

A ready-made pile such as a steel pipe pile is placed as the pile body 1, and the leveling concrete 7 is placed on the ground surface 5b where the original ground 5a is lowered so that a predetermined protrusion length can be secured. Filling concrete (not shown) for stiffening is filled over a predetermined height in the pile of the pile head 2 to perform pile head treatment (FIG. 8 (a)).

The pile head joint pipe 20 is placed on the leveled concrete 7 so that the plane center of the pile head joint pipe 20 coincides with the regular position (pile center) of the pile body 1 (FIG. 8 (b)). ..

The filling concrete 23 is filled in the gap between the internal space 22 of the pile head joint pipe 20 and the pile body 1. At this time, the casting height of the filled concrete 23 is slightly higher than the upper end of the pile head joint pipe 20 so that the pile head connecting portion 38 of the precast joint 30 connected to the upper part of the pile head joint pipe 20 can be installed. Up to a low position. Next, the peripheral ground 5c of the board-lowering portion around the pile head joint pipe 20 is backfilled to the ground surface 5a at the installation level of the structural portion of the pile foundation (FIG. 8 (c)).

While inserting the precast joint body 30 on the ground surface 5a in which the surrounding ground 5c is backfilled and the vertical bar 25 erected in the pile head joint pipe 20 through the through hole 39 formed in the precast joint body 30. Place it (Fig. 9 (d)). The vertical bar 25 and the hoop bar 29 (FIG. 7 (b)) function as reinforcing joint bars for integrating the precast joint body 30 and the pile head joint pipe 20. Further, in the clearance (gap) between the pile head joint pipe 20 and the pile head connecting portion 38 of the precast joint body 30 which are vertically stacked, the filling concrete 23 and the pile head connecting portion 38 are integrated. Therefore, the solidifying material 50 is filled along the filling path 49 described later (FIG. 9 (e)).

When the precast joint body 30 is placed on the ground surface 5a, the end position of the beam main bar joint bar 35 protruding from the side surface of the precast joint body 30 and the beam main bar 17 to which the beam main bar joint bar 35 is joined (FIG. 9). It is important that the bar arrangement position of (e)), that is, the axial center direction of the foundation beam 15 is accurately matched.

Next, as shown in FIG. 9E, leveling concrete 6 for installing the foundation beam 15 to be connected to the precast joint 30 is cast on the ground surface 5a, and the precast concrete foundation beam 15 is placed. , It is placed on the leveled concrete 6 facing the beam joint surface of the precast joint 30 that has already been installed and separated by a predetermined separation portion 16. Further, the end of the beam main bar 17 protruding from the end of the foundation beam 15 and the beam main bar joint bar 35 of the precast joint body 30 are joined by a mechanical joint 18, and the stirrup 45 required for the separation portion 16 is arranged. Stroke and attach a side formwork (not shown) corresponding to the beam width.

Joined concrete 46 having the same strength as the concrete strength of the foundation beam 15 is placed in the separated portion 16 surrounded by the side formwork. At the same time as the concrete placing work of the joint concrete 46, the cast-in-place concrete portion 47 for completing the outer shape of the column-beam joint portion is constructed so as to surround the precast joint body 30. As a result, the pile head 2 (pile cap) can be made into a rigid structure, and the pile foundation structure 10 in which the pile head 2 and the foundation beam 15 are rigidly joined can be constructed (FIG. 10 (f)).

After the joining of each foundation beam 15 and the precast joint 30 is completed, as shown in FIGS. 10 (f) and 10 (g), the column main bar joint muscle 36 projects from the upper surface of the column joint 32 of the precast joint 30. The precast concrete column 40 is built using the position as a guide, and the main bar joints 36 of each column and the main bars 43 of the precast concrete column 40 are joined by a mechanical joint 42. The column 40 to be erected may be a reinforced concrete column constructed on site. In that case, the column main bar and hoop bar are built based on the column main bar joint bar, the formwork is assembled, and the concrete placing work is performed to construct the reinforced concrete column.

In FIG. 11, the precast joint 30 is placed on the upper surface of the pile head joint 20 so that each column main bar joint 36 of the pile head joint 20 is inserted into the through hole formed in the precast joint 30. Solidified along a filling path 49 composed of a gap 48 between a convex pile head connecting portion 38 formed on the bottom surface of the precast joint 30 and the upper surface of the pile head joining pipe 20 and a through hole 39, which are connected vertically. It shows a state in which the material 50 is filled. By solidifying the solidifying material 50 filled in this way, the precast joint body 30 and the pile head joint pipe 20 are integrated.

FIG. 12 shows an embodiment in which the joint structure of the pile head 2 and the precast joint 30 is a semi-fixed method. The vertical bars 25 as shown in FIG. 11 are not arranged in the pile head joint pipe 20 having the joint structure shown in the figure, and the pile head connection of the precast joint 30 is connected on the pile head joint pipe 20. The portion 38 is placed in a predetermined position while holding a predetermined clearance (gap) 48 via a spacer (not shown), the clearance 48 is filled with the solidifying material 50, and the pile head joint pipe 20 and the precast joint 30 The space is fixed. In this semi-fixed joint structure, the normal vertical load is supported by the pile via the pile head 2, but the bending moment generated in the pile head 2 at the time of an earthquake is the beam-column joint formed by the precast joint 30. Is not transmitted to.

In each attached figure, a mode in which the foundation beam is joined from four directions orthogonal to the precast joint 30 is drawn, but the foundation beam is I-shaped (one direction) and L-shaped (2) in a plan view. It can be applied to outer peripheral piles and corner piles that are joined to the pile head 2 so as to form a T-shape (three directions). For example, when the foundation beams are joined so as to form an L shape, it is preferable to incorporate the beam main bar joints into the precast joint so as to face two directions at right angles in accordance with the extension direction of the foundation beam.

In the above, the foundation beam 15 has been described as an example of the structural part of the pile foundation to be joined to the precast joint body 30, but it is assumed that the structural part of the pile foundation is a part of the foundation footing in addition to the foundation beam. it can. In that case, it is preferable that the beam main bar joint bar incorporated in the precast joint is provided at a position where a part of the reinforcement of the foundation footing can be reliably joined to the reinforcing bar on the precast joint side.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope shown in each claim. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

1 Pile body 2 Pile head 5a, 5b Ground surface 10 Pile foundation structure 15 Foundation beam (structural part)
16 Separation part 17 Beam main bar 20 Joint part Steel pipe 24 Inner circumference concrete 25 Vertical bar 30 Precast joint 35 Beam main bar joint bar 36 Column main bar joint bar 40 Precast concrete pillar 43 Column main bar 46 Joint concrete

Claims (7)

A pile with the pile head protruding from the ground surface for a predetermined length,
The structural part of the pile foundation to be joined to the pile head,
The internal space has an annular shape in a plan view, and the pile head is installed on the ground surface lowered so that the pile head is located substantially in the center of the internal space. Pile head joint pipe that supports the head and
The ground around the pile head joint pipe is installed on the backfilled ground surface, and includes a precast joint body that holds the main bar end of the structural portion of the pile foundation and the main bar joint to be jointed.
The structural portion of the pile foundation is installed with a predetermined separation portion from the outer peripheral surface of the precast joint, and the joint concrete is formed in a state where the main bar end of the structural portion of the pile foundation and the main bar joint bar are joined. A pile foundation structure characterized in that it is integrated with the precast joint body via the pile head and is constructed so as to be vertically stacked with the pile head joint pipe and joined to the pile head. The pile foundation structure according to claim 1, wherein the pile head joint pipe is a precast reinforced concrete member having a steel pipe concrete composite structure composed of an outer skin steel pipe and an inner peripheral concrete portion. The pile foundation structure according to claim 1, wherein the pile head joint pipe has joint vertical bars arranged in the inner peripheral concrete portion. The precast joint includes a pile head connecting portion that can be loosely fitted in the internal space of the pile head joining pipe, and a lower joint portion including the main bar joining bar that is joined to the main bar end of the structural portion of the pile foundation. The pile foundation structure according to claim 1, which is a precast reinforced concrete member including an upper joint portion on which a column erected on the upper surface can be placed. The pile foundation structure according to claim 4, wherein the precast joint body holds, in addition to the main bar joint bar, a column main bar joint bar to be joined to the main bar of the column. In the precast joint body, a through hole through which a joint vertical streak erected in the pile head joint pipe can be inserted is formed, and the joint vertical streak is held in the through hole to form a through hole with the pile head joint pipe. The pile foundation structure according to claim 1, wherein the pile foundation structure is integrated. The pile foundation structure according to claim 1, wherein the structural portion of the pile foundation is a reinforced concrete foundation beam or foundation footing.

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