JP7232660B2 - pile foundation structure - Google Patents

Description

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

In the joint structure between the pile head of the pile body and the structural part such as the underground beam of the reinforced concrete structure and the foundation footing, the pile head and the structural part of the pile foundation are integrated to ensure a predetermined strength and rigidity. In addition, a large number of reinforcing bars are arranged in a narrow joint structure space, and labor-intensive and complicated reinforcing bar arrangement work is required.

In order to solve this problem, a joint structure between a beam and a pile has been proposed in which an annular member that functions as a fixing portion for the end of the main reinforcement of the beam is loosely fitted around the outer periphery of the steel pipe pile (Patent Document 1). In this joint structure, the ends of the beam main rebars are attached so that the ends of the rebars line up with a fixing plate attached to a predetermined position of a fixing ring, which is an annular band plate provided on the outer periphery of the steel pipe pile. For this reason, when a large-diameter reinforcing bar is used for the beam main reinforcement, it is difficult to secure a predetermined fixing length and rigidity of the joint structure with an annular member composed only of a fixing plate and a fixing ring.

On the other hand, Patent Document 2 discloses a foundation structure in which the rigidity of the pile head and the foundation footing is increased. In this foundation structure, a predetermined space (pile head insertion part) is secured at the outer peripheral position of the pile head, precast foundation members are installed, a predetermined stress transmission member is provided in the pile head insertion part, and filler material is placed in the space. By filling the pile head, the pile head and the precast foundation member are integrated.

JP-A-2001-342684 JP 2016-70028 A

In the foundation structure disclosed in Patent Document 2, the joint of the pedestal installed on the upper part of the precast foundation member is rigidly joined to the end of the steel beam, and then the entire joint is covered with concrete. Concreting of the whole is carried out. Therefore, the foundation structure disclosed in Patent Literature 2 has a different structure from the structure in which the ends of the main reinforcing bars of the underground beams are joined directly to the pile head side with a sufficient fixing length secured. For this reason, a pile foundation structure that can easily and reliably join and hold the beam end main reinforcement on the pile head side is required in the joint structure with the underground beam or foundation footing of the reinforced concrete structure.

Therefore, the object of the present invention is to solve the problems of the conventional technology described above, and to use a precast joining member that can join and hold the fixing end of the reinforcing bar of the underground beam or foundation footing. To provide a pile foundation structure which can be easily and surely joined to structural parts such as a center beam and a foundation footing.

In order to achieve the above object, the present invention provides a pile driven with a pile head having a predetermined protruding length from the ground surface, a structural portion of the pile foundation joined to the pile head, and a plan view It is made of a precast concrete member in which the outer and inner peripheral surfaces of the inner concrete are coated with a steel plate, and has an annular shape, and holds anchoring bars that are joined to the ends of the main bars of the structural part of the pile foundation, an annular joint installed around the pile head so that the pile head is positioned substantially at the center of the annular inner peripheral space, and the structural part of the pile foundation is the annular joint It is installed with a predetermined distance from the outer peripheral surface, and the main reinforcement end of the structural part of the pile foundation and the anchoring reinforcement are joined in a state where the annular joint is joined , and the joint concrete is placed in the distance. The inner peripheral space of the annular joined body is filled with filling concrete, and the pile head and the structural portion of the pile foundation are joined.

It is preferable that the annular joint is formed with a through hole capable of inserting and holding the anchoring bar.

It is preferable that the fixing bar is inserted and held in the through hole so as to protrude by a predetermined fixing length toward the inner peripheral space of the annular joint.

The structural portion of the pile foundation is preferably an underground beam or foundation footing made of reinforced concrete.

It is preferable that the annular joint body has a shear resistance body formed at a joint position of the outer peripheral surface with the structural portion of the pile foundation.

It is preferable that a shear resistor is formed on the inner peripheral surface of the annular joined body.

BRIEF DESCRIPTION OF THE DRAWINGS The plane sectional view which showed the internal structure of one Embodiment of the pile foundation structure of this invention with a partial cross section. Fig. 2 is a front cross-sectional view showing the internal structure of the pile foundation structure along the II-II cross-sectional line in Fig. 1; A plan view and a cross-sectional view showing the external shape of an annular anchoring body used in the pile foundation structure of the present invention. FIG. 4 is a cross-sectional view showing a state in which end fixing bars are attached to the annular fixing body shown in FIG. 3 ; 4A and 4B are a plan view and a cross-sectional view showing a state in which shear resistors are attached to the inner and outer surfaces of the annular fixing body shown in FIG. 3; Explanatory diagrams showing the construction procedure of the pile foundation structure of the present invention (No. 1: (a) to (c)). Explanatory drawing (the 2: (d), (e)) which showed the construction procedure of the pile foundation structure of this invention.

Hereinafter, the configuration of the pile foundation structure of the present invention will be described with reference to the accompanying drawings. 1 and 2 show, as an embodiment of the pile foundation structure of the present invention, an underground beam 15 and the pile head of the pile body 1 arranged vertically and horizontally around the pile head of the pile body 1 in plan view. Part of the external appearance and internal configuration of the pile foundation structure 10 that joins the part 2 is shown.

The pile body 1 of this embodiment is made of a steel pipe pile with a pile outer diameter of 1,000 mmφ, and as shown in FIG. A rectangular steel pipe column (550 mm square) 4 is erected on the top end surface of the column base plate 3 interposed therebetween.

The underground beam 15 of this embodiment is made of a precast reinforced concrete member with a beam length of 2,000 mm and a beam width of 1,000 mm. It is arranged vertically and horizontally around the body so as to form a cruciform shape when viewed from the top with a predetermined spaced portion 16, and is placed on the base concrete 6 laid flat on the ground surface 5, and the joint concrete 35 It is joined to the pile head 2 of the pile body 1 via an annular joint 20 (which will be described later).

The annular joined body 20 of this embodiment is the main constituent member of the present invention that joins the pile head portion 2 of the pile body 1 and the underground beam 15 . 3, the annular joined body 20 has a hollow cylindrical shape with an annular plane cross section, and the outer peripheral surface and the inner peripheral surface are covered with an outer peripheral steel plate 21 and an inner peripheral steel plate 22, and the outer peripheral steel plate 21 It consists of a precast concrete steel plate composite member in which an internal concrete 23 is densely filled between the steel plate 22 and the inner peripheral steel plate 22 . The dimensions of the annular joint 20 in this embodiment are an outer diameter of 2,300 mm, an inner diameter of 1,300 mm, a height of 2,200 mm, and a thickness of the internal concrete 23 of 500 mm. These dimensions are set based on the dimensions of the vehicle bed on which the factory-manufactured annular joint 20 can be mounted, and if there are no dimensional restrictions during transportation, the dimensions may be larger than the above dimensions. can. Moreover, it is preferable to set the inner diameter of the annular joined body 20 in consideration of the construction error of the driven pile position. For example, the inner diameter of the annular joint 20 is preferably 15% or more of the outer diameter of the pile. By adjusting the installation position of the annular joint 20, it is possible to absorb the displacement of the driving position of the pile body 1, etc. As a result, the underground beam 15 can be installed with high accuracy. The plate thickness of the outer peripheral steel plate 21 and the inner peripheral steel plate 22 of this embodiment is 16 mm. Moreover, the concrete strength of the inner concrete 23 is 27 N/mm ² . The thickness of the steel plate, the internal concrete 23 and the strength of the filling concrete 36 to be described later are preferably set as appropriate according to the design conditions of the pile foundation structure 10 . Note that when high-strength concrete is used, the annular joined body 20 can also be a precast concrete member that does not have the outer peripheral steel plate 21 and the inner peripheral steel plate 22 . In addition, in order to integrate the internal concrete 23 with the outer peripheral steel plate 21 and the inner peripheral steel plate 22, it is preferable to dispose a shear resistance material such as flat steel or round steel on the inner surface side of the steel plate (internal concrete 23 side). .

As shown in FIG. 3, six through-holes 24 are arranged horizontally in the upper and lower portions of the annular joint 20 in two stages. The through-hole 24 consists of a sheath tube 25 of a predetermined tube diameter embedded in a predetermined position so that both ends thereof are supported by the steel plates 21 and 22 . The sheath tube 25 used in this embodiment has an inner diameter of 42 mmφ, and a deformed steel bar of about D35 is inserted into the sheath tube 25 to hold the reinforcement in the hole by grout filling. The inner diameter of the sheath tube 25 may be set according to the diameter of the short reinforcing bars 31 inserted into the through holes 24 (see FIG. 4).

As shown in FIGS. 1 and 2, a short fixing reinforcing bar (hereinafter referred to as a short reinforcing bar 31 ) and the ends of the beam main reinforcements 17 of the underground beams 15 are joined, and the joining concrete 35 is cast-in-place concrete at the predetermined separation portion 16 between the annular joint 20 and the end surface of the underground beam 15. is cast as Filling concrete 36 is placed in the inner peripheral space 26 of the annular joint 20 . As a result, the pile head 2 of the pile body, the annular joint 20, and the main body of the underground beam 15 are integrally constructed, and the rigid connection of each member of the pile foundation structure 10 is realized.

Each figure in FIG. 4 shows a state in which a short reinforcing bar 31 as a beam end fixing bar is inserted into each through hole 24 of the annular joint 20 carried to the construction site and fixed and held by the filling grout. As described above, this short reinforcing bar 31 has the same diameter as the beam main reinforcing bar 17 of the underground beam 15 to be joined, and is joined to the beam main reinforcing bar 17 via a mechanical joint (see FIGS. 1 and 2). A fixing nut 32 is screwed to the end of the short reinforcing bar 31 . Further, the projection length of the short reinforcing bar 31 on the side of the fixing nut 32 is set in consideration of the fixing effect of the fixing nut 32 so as to secure the required fixing length of the beam main reinforcement 17 of the underground beam 15 .

Each figure in FIG. 5 shows shear resistance members provided on the beam joint surface of the outer peripheral surface of the annular joint 20 and the inner peripheral surface. As shown in FIGS. 1 and 2, the annular joint 20, which is a precast concrete member, and the underground beam 15 are installed with a predetermined distance 16 that includes a reinforcing bar joint between them. Joining concrete 35 that is post-placed on-site is placed in the spaced portion 16, and the annular joined body 20 and the underground beam 15 are integrally joined. Filling concrete 36 is placed in the inner peripheral space 26 of the annular joint 20 after installation. The underground beam 15 , the annular joint 20 and the pile head 2 are integrated with the joint concrete 35 and the filling concrete 36 .

In order to resist the shear force generated on the joint surface between the annular joint 20 and the joint concrete 35 and the joint surface between the annular joint 20 and the filling concrete 36, the annular joint 20 is provided with a shear key as a shear resistance member. are attached to the outer peripheral steel plate 21 and the inner peripheral steel plate 22 . On the outer peripheral steel plate 21, shear keys are attached to the joint range with the underground beam 15, as indicated by the phantom lines in FIG. 5(a). As a shear key, a plurality of deformed steel bars 37 or shaped steels 38 are attached to the outer peripheral steel plate 21 at predetermined intervals over the height direction of the annular joined body 20 . FIG. 4(b) shows an example of attachment of a deformed steel bar 37 (right half of the figure) and a section steel 38 (left half of the figure).

On the other hand, shear keys similar to those of the outer steel plate 21 are attached to the inner steel plate 22 in order to achieve integration with the filling concrete 36 filled in the inner space 26 of the annular joint 20 . The inner concrete 36 filling the inner peripheral space 26 and the inner concrete 23 of the annular joint 20 are brought into close contact with each other by the shear key, so that the annular joint 20 and the inner concrete 36 are integrated. Alternatively, a part of the inner peripheral steel plate 22 may be removed to expose the surface of the inner concrete 23, and the annular joint 20 and the filling concrete 36 may be integrated by this exposed portion. Since a portion of the short reinforcing bars 31 and the fixing nuts 32 are protruded and buried in the filling concrete 36, the short reinforcing bars 31 can be sufficiently fixed.

Hereinafter, construction procedures for constructing the pile foundation structure 10 of the present invention will be described with reference to FIGS.

A ready-made pile such as a steel pipe pile is driven as the pile body 1, and filling concrete (not shown) for stiffening is driven into the pile of the pile head 2 (Fig. 6(a)). The circular joint body 20 is arranged so that the holding position of the short reinforcing bars 31 of the circular joint body 20 and the reinforcement arrangement position of the beam main reinforcement 17 to which the short reinforcing bars 31 are joined, that is, the axial direction of the underground beam 15, are precisely matched. is placed on the ground surface 5 which is shaped substantially horizontally. At this time, the cross-sectional center of the annular joint 20 and the cross-sectional center of the pile may be substantially concentric, and the error of the pile construction position with respect to the installation position of the underground beam 15 can be absorbed at this stage (Fig. 6 (b) )). At this time, as shown in the figure, the short reinforcing bars 31 are inserted and held in advance at predetermined positions in the through holes 24 of the annular joint 20, so that the work of positioning the underground beams 15 with the beam main bars 17 is not required. It can be done easily and with high accuracy. At this stage, a steel pipe column 4 is erected on each pile head 2 through a column base plate 3 (Fig. 6(c)). For this purpose, base concrete is placed, and an underground beam 15 made of precast concrete is placed at a predetermined position on the base concrete. Further, the end of the main reinforcement projecting from the end of the underground beam 15 and the short reinforcing bar 31 of the annular joint 20 are joined by a mechanical joint 18 (FIG. 7(d)). In this embodiment, the beam main reinforcement 17 of the underground beam 15 and the short reinforcing bars 31 of the annular joint 20 are joined using sleeves or couplers pre-attached to the beam main reinforcement 17 of the underground beam 15 as the mechanical joints 18 . ing.

In order to finally integrate the pile head 2 and the underground beam 15 as the foundation structure, joint concrete 35 is placed in the spaced portion 16 between the annular joint 20 and the precast concrete underground beam 15. . For this purpose, additional reinforcement is arranged in the spaced portion 16 between the annular joint 20 and the underground beam 15, a side formwork (not shown) corresponding to the width of the beam is installed, and the underground beam is placed in the formwork. A joint concrete 35 having the same strength as the concrete strength of No. 15 is placed. At the same time, filling concrete 36 is placed in the inner peripheral space 26 of the annular joint 20, and the pile head 2 and the column base of the column 4 are hardened. While making the pile head 2 (pile cap) into a rigid structure by this, the pile foundation structure 10 which rigidly joined the pile head 2 and the underground beam 15 can be constructed|assembled (FIG.7(e)).

Each of the attached drawings shows a mode in which the underground beams 15 are joined from four directions orthogonal to the annular joint 20, but the underground beams 15 are L-shaped or T-shaped in plan view. It can be applied to peripheral piles and corner piles that are joined to the pile head 2 so as to form a. In this case, the through-holes 24 provided in the annular joint 20 may be provided in two or three directions perpendicular to the extending direction of the underground beam 15, for example. Further, it is conceivable that the structural portion joined to the annular joint 20 is part of the foundation footing in addition to the underground beam 15 described above. In that case, the through hole 24 of the annular joint 20 is preferably provided at a position where a part of the reinforcing bars of the foundation footing can be reliably joined to the annular joint 20 .

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated in each claim. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

1 pile body 2 pile head 4 pillar (steel pipe pillar)
10 Pile foundation structure 15 Underground beam (structural part)
16 Separation portion 17 Main beam reinforcement 18 Mechanical joint 20 Annular joint 21 Peripheral steel plate 22 Inner peripheral steel plate 23 Internal concrete 24 Through hole 26 Inner peripheral space 31 Fixing bar (short reinforcing bar)
35 Joining concrete 36 Filling concrete

Claims (6)

A pile driven with a pile head having a predetermined protruding length from the ground surface;
a structural portion of the pile foundation joined to the pile head;
It consists of a precast concrete member that has an annular shape when viewed from above and the outer and inner peripheral surfaces of the inner concrete are coated with steel plates, and holds the anchoring reinforcement that is joined to the end of the main reinforcement of the structural part of the pile foundation. and an annular joint installed around the pile head such that the pile head is positioned substantially at the center of the annular inner peripheral space,
The structural portion of the pile foundation is installed with a predetermined distance from the outer peripheral surface of the annular joint body, and the end of the main reinforcement of the structural portion of the pile foundation and the anchor reinforcement are joined to the annular joint body. and integrated with joint concrete placed in the separated part ,
The inner peripheral space of the annular joint is filled with filling concrete,
A pile foundation structure, wherein the pile head and the structural portion of the pile foundation are joined together. The pile foundation structure according to claim 1, wherein the annular joint is formed with a through hole into which the anchoring bar can be inserted and held. The pile foundation structure according to claim 2 , wherein the anchoring bar is inserted and held in the through hole so as to protrude toward the inner peripheral space of the annular joint by a predetermined anchoring length. The pile foundation structure according to claim 1, wherein the structural portion of the pile foundation is a reinforced concrete underground beam or foundation footing. 2. The pile foundation structure according to claim 1, wherein said annular joined body has a shear resistance body formed at a joint position of said outer peripheral surface with said structural portion of said pile foundation. The pile foundation structure according to claim 1, wherein the annular joint body has a shear resistance body formed on the inner peripheral surface.

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