Pile foundation structure, and construction method of pile foundation structure

Abstract

To reliably install a precast concrete foundation member which is installed between foundation piles to form a beam, and easily construct a strong structure in a short period.SOLUTION: A pile foundation structure 1 includes: a foundation pile 2; a concrete pile foundation member 30 provided above the foundation pile 2, where a beam main reinforcement unit 35 which forms an end of a beam 4, and a foundation reinforcement unit 33 which is formed into a rectangular shape are embedded; a self-leveling layer 7 which is formed of a self-leveling material on a ground surface Gf or a leveling concrete layer 6; a precast concrete foundation member 40 that is installed on the self-leveling layer 7, where the height is adjusted by the self-leveling layer 7 and a lower surface 40b is partially supported; and a beam part cast-in-piece concrete part 8 which is provided on the ground surface Gf or the leveling concrete layer 6, between the pile foundation member 30 and the foundation member 40. The beam main reinforcement unit 35, the foundation member 40, and the beam part cast-in-place concrete part 8 are connected to each other through beam main reinforcements 91A and 91B which are continuously installed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a pile foundation structure including foundation piles and precast concrete foundation members that are installed between the foundation piles to form beams, and a method for constructing the pile foundation structure. [Background technology]

[0002] When constructing the pile foundation of a building, components such as footings to be installed on the heads of the foundation piles and components constituting the foundation beams are sometimes manufactured as precast concrete foundation components and installed on site. In such cases, it is necessary to adjust the height of the precast concrete foundation components so that they are installed at the intended height. For example, Patent Document 1 describes a configuration in which height-adjusting members made of non-shrink mortar are installed around a foundation pile in order to position and adjust the height of the foundation member when the precast concrete foundation member is placed on the head of the foundation pile. Patent Document 1 also describes the use of a precast concrete slab as the height-adjusting member. Furthermore, Patent Document 2 describes a configuration in which, when a precast concrete footing member is installed on the pile head, a mounting plate made of a flat concrete plate is installed on the ground surrounding the pile head. Furthermore, Patent Document 3 describes a configuration in which a leveling material made of laminated thin metal plates is placed on top of a sacrificial concrete layer, and a foundation member that serves as a footing is provided on top of this leveling material.

[0003] In Patent Document 1, when non-shrink mortar is used as the height adjustment member, a surface finishing treatment is required. In addition, it is necessary to wait for the non-shrink mortar to harden before installing the foundation member. For this reason, there is a possibility that construction cannot be carried out easily and in a short time. In contrast, when a concrete plate as described in Patent Documents 1 and 2 is used as the height adjustment member, or when a laminate of thin metal plates as described in Patent Document 3 is used, the installation work of the level adjustment member for adjusting the height of the foundation member can be performed by simply placing a concrete plate or a laminate of thin metal plates that have been manufactured in advance at the site. Therefore, compared to the case where non-shrink mortar is used, there is a possibility that the construction can be completed in a short period of time. However, when the area of ​​the level adjustment member is small, when the foundation member is installed on the level adjustment member, the load of the foundation member is too locally concentrated, and a punching shear force acts on the ground or the basin concrete under the level adjustment member, which may destroy the ground or the basin concrete. Therefore, there is a possibility that the foundation member cannot be installed reliably.

[0004] In order to reduce the punching shear force as described above, the area of ​​the leveling material can be increased to distribute the load of the precast concrete members over a wide area. However, in this case, the leveling material becomes large, and handling during transportation and installation becomes difficult. Therefore, construction may become difficult. The above situation also applies to foundation members that are placed between foundation piles to form beams (foundation beams). In other words, it is desirable to reliably install precast concrete foundation members that are placed between foundation piles to form beams, and to easily build a strong structure in a short period of time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6624797 [Patent Document 2] JP 2015-200094 A [Patent Document 3] JP 2022-124976 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problem that the present invention aims to solve is to provide a pile foundation structure that enables precast concrete foundation members, which are placed between foundation piles to form beams, to be reliably installed, thereby enabling a strong structure to be constructed easily in a short period of time. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention employs the following means. That is, the pile foundation structure of the present invention is a pile foundation structure comprising foundation piles and foundation members of precast concrete construction that are installed between the foundation piles to form beams, the pile foundation member being made of concrete in which the foundation piles, beam main reinforcement units forming the ends of the beams and provided above the foundation piles, and foundation reinforcing bars formed in a rectangular parallelepiped shape are embedded, a self-leveling layer formed of a self-leveling material on the ground surface or on a basal concrete layer, the foundation member being installed on the self-leveling layer and having its underside partially supported by the self-leveling layer as its height is adjusted, and a cast-in-place concrete beam portion section that is provided on the ground surface or on the basal concrete layer between the pile foundation member and the foundation member, and the beam main reinforcement units, the foundation member, and the cast-in-place concrete beam portion section are connected via beam main reinforcement units that are installed continuously. According to the above-mentioned configuration, the pile foundation structure includes foundation piles, pile foundation members provided above the foundation piles, foundation members installed between the foundation piles to form beams, and on-site cast concrete beam portions provided between the pile foundation members and the foundation members. The beam main reinforcement units of the pile foundation members, the foundation members, and the on-site cast concrete beam portions are connected via the continuously installed beam main reinforcements, so that the foundation members are firmly joined to the pile foundation members via the on-site cast concrete beam portions. This improves the stability of the structure and realizes a strong pile foundation structure with excellent rigidity and earthquake resistance. In such a structure, the precast concrete foundation members forming the beams are supported on the ground surface or on a basin concrete layer with their height adjusted by a self-leveling layer formed of a self-leveling material. After poured into the formwork, the self-leveling material has self-flattening properties and spreads evenly by gravity, so that a smooth surface can be easily formed. Furthermore, compared to mortar, the self-leveling material generally dries quickly. Therefore, by forming the members for adjusting the height with the self-leveling material, construction can be easily performed and the construction period can be reduced compared to the case of using mortar, for example. Moreover, the self-leveling layer can be easily formed by providing a formwork so as to surround the portion on the ground surface or on the basin concrete layer where the self-leveling layer is to be formed, and pouring the self-leveling material into the formwork. In such work, even if the layer thickness of the self-leveling layer is increased or its size (area) is increased slightly, the ease of construction is unlikely to be impaired. Therefore, it is easily possible to set the predetermined height (predetermined layer thickness) and size required for the self-leveling layer to a level that does not cause destruction of the ground or basin concrete due to punching shear force, without impairing the ease of construction. Therefore, it is possible to reliably install the foundation members of the precast concrete structure while suppressing punching shear. In particular, the underside of a precast concrete foundation member is partially supported by the self-leveling layer. In other words, the entire underside of a precast concrete foundation member is not supported by the self-leveling layer. For this reason, the size (area) of the self-leveling layer can be significantly reduced compared to, for example, a case in which a large self-leveling layer is provided so that the entire underside of a precast concrete foundation member is supported by the self-leveling layer. This makes construction easier. In this way, it becomes possible to provide a pile foundation structure that can surely install precast concrete foundation members that are installed between the foundation piles to form a beam, and can easily construct a strong structure in a short period of time.

[0008] The method for constructing the pile foundation structure of the present invention is a method for constructing a pile foundation structure including a foundation pile and a precast concrete foundation member that is installed between the foundation piles to form a beam. The method includes the steps of arranging, above the foundation pile, a beam main reinforcement unit that forms an end portion of the beam and a foundation reinforcement unit formed in a rectangular parallelepiped shape; forming a self-leveling layer portion with a self-leveling material on the ground surface or on a discarded concrete layer; installing the precast concrete foundation member on the self-leveling layer so that the lower surface is partially supported while adjusting the height by the self-leveling layer; placing concrete on-site to construct a beam partial in-situ cast concrete portion between a pile foundation member that buries the foundation reinforcement unit and the beam main reinforcement unit and the foundation member; and in the step of constructing the beam partial in-situ cast concrete portion, the beam main reinforcement unit, the foundation member, and the beam partial in-situ cast concrete portion are connected via continuously installed beam main reinforcements. The method for constructing a pile foundation structure of the present invention is a method for constructing a pile foundation structure comprising foundation piles and foundation members of precast concrete construction that are installed between the foundation piles to form beams, the method including the steps of: providing a pile foundation member that is partially or entirely formed of precast concrete construction and that embeds beam main reinforcement units that form the ends of the beams and foundation reinforcing bars units formed in a rectangular parallelepiped shape above the foundation piles; forming a self-leveling layer portion with a self-leveling material on the ground surface or on a basin concrete layer; installing the precast concrete foundation member on the self-leveling layer so that the lower surface is partially supported while the height is adjusted by the self-leveling layer; and pouring concrete on site to construct a beam portion cast in site concrete portion between the pile foundation member and the foundation member, wherein the step of constructing the beam portion cast in site concrete portion is characterized in that the beam main reinforcement units, the foundation member, and the beam portion cast in site concrete portion are connected via the beam main reinforcement units that are installed continuously. According to this configuration, a pile foundation structure is constructed that includes foundation piles, pile foundation members in which foundation reinforcing bar units are buried above the foundation piles, foundation members that are installed between the foundation piles to form beams, and on-site cast concrete beam sections installed between the pile foundation members and the foundation members. The beam main reinforcement units, foundation members, and on-site cast concrete beam sections of the pile foundation members are connected via the successively installed beam main reinforcements, so that the foundation members are firmly joined to the pile foundation members via the on-site cast concrete beam sections. This improves the stability of the structure and allows for the realization of a robust pile foundation structure with excellent rigidity and earthquake resistance. In such a structure, the precast concrete foundation members forming the beams are supported on the ground surface or on a basin concrete layer with their height adjusted by a self-leveling layer formed of a self-leveling material. After poured into the formwork, the self-leveling material has self-flattening properties and spreads evenly by gravity, so that a smooth surface can be easily formed. Furthermore, compared to mortar, the self-leveling material generally dries quickly. Therefore, by forming the members for adjusting the height with the self-leveling material, construction can be easily performed and the construction period can be reduced compared to the case of using mortar, for example. Moreover, the self-leveling layer can be easily formed by providing a formwork so as to surround the portion on the ground surface or on the basin concrete layer where the self-leveling layer is to be formed, and pouring the self-leveling material into the formwork. In such work, even if the layer thickness of the self-leveling layer is increased or its size (area) is increased slightly, the ease of construction is unlikely to be impaired. Therefore, it is easily possible to set the predetermined height (predetermined layer thickness) and size required for the self-leveling layer to a level that does not cause destruction of the ground or basin concrete due to punching shear force, without impairing the ease of construction. Therefore, it is possible to reliably install the foundation members of the precast concrete structure while suppressing punching shear. In particular, when constructing the above-mentioned pile foundation structure, the underside of the precast concrete foundation member is partially supported by the self-leveling layer. In other words, the entire underside of the precast concrete foundation member is not supported by the self-leveling layer. For this reason, the size (area) of the self-leveling layer can be significantly reduced compared to, for example, a case in which a large self-leveling layer is provided so that the entire underside of a precast concrete foundation member is supported by the self-leveling layer. This makes construction easier. In this way, it is possible to realize a pile foundation structure that enables precast concrete foundation components, which are placed between the foundation piles to form beams, to be reliably installed, allowing for the construction of a strong structure easily in a short period of time.

[0009] In one aspect of the present invention, in the method of constructing a pile foundation structure of the present invention, the foundation member is supported by the self-leveling layer at both end sides in the extension direction of the beam, or at the central side in the extension direction of the beam, by the self-leveling layer. According to this configuration, both ends or the center of the beam in the extension direction are supported by the self-leveling layer, so that the entire lower surface of the beam is supported by the self-leveling layer. This allows the size (area) of the self-leveling layer to be significantly reduced compared to a case where the self-leveling layer is provided large so that the entire lower surface of the beam is supported by the self-leveling layer. Therefore, construction can be performed more easily. Effect of the Invention

[0010] According to the present invention, it is possible to reliably install precast concrete foundation members, which are placed between foundation piles to form beams, and to easily construct a strong structure in a short period of time. [Brief description of the drawings]

[0011]

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[0012] The present invention relates to a pile foundation structure including foundation piles and precast concrete foundation members that are installed between the foundation piles to form beams, and a method for constructing the pile foundation structure. The entire bottom surface of the foundation member is not supported by a self-leveling layer, but the foundation member is supported by a self-leveling layer provided only on the edge side or the center side of the bottom surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the accompanying drawings, an embodiment for carrying out a pile foundation structure and a method for constructing a pile foundation structure according to the present invention will be described based on the drawings. Fig. 1 shows a plan view illustrating the configuration of a pile foundation structure according to an embodiment of the present invention. Fig. 2 is a perspective view illustrating a part of the pile foundation structure in Fig. 1. Fig. 3 is a cross-sectional view taken along the line II in Fig. 2. In Figs. 2 and 3, in order to explain the internal structure of the pile foundation structure in detail, some of the concrete poured on site, including around the piles, has not been poured and the reinforcing bars are exposed. As shown in Figures 1 to 3, the pile foundation structure 1 of this embodiment mainly comprises a foundation pile 2 (see Figures 1 and 3), a pile foundation member 30, a foundation member 40, a self-leveling layer 7, and a beam portion cast-in-place concrete section 8 (see Figure 1). As shown in Fig. 3, a plurality of foundation piles 2 are buried in the ground G. The foundation piles 2 support, from below, columns (not shown) of the superstructure of the building supported by the pile foundation structure 1. The pile head 2t of each foundation pile 2 protrudes upward from the bottom surface of a root cutting recess Ga formed so as to be recessed downward from the ground surface Gf.

[0013] As shown in Fig. 2 and Fig. 3, the pile foundation member 30 is provided on the pile head portion 2t of the foundation pile 2. The pile foundation member 30 forms a footing 3. A beam (girder) 4 is joined to the footing 3. The pile foundation member 30 includes a foundation reinforcing bar unit 33 formed in a rectangular parallelepiped shape, a beam main reinforcement unit 35 forming the end of the beam 4, a column main reinforcement unit 39 connected to a column of the superstructure, and a concrete portion 37 (see Fig. 1). The foundation reinforcing bar unit 33 is a reinforcing bar embedded in the concrete portion 37 that forms the footing 3. The foundation reinforcing bar unit 33 is formed by providing reinforcing bars extending in the horizontal and vertical directions so as to surround the top of the pile head 2t of the foundation pile 2, and is formed into a rectangular parallelepiped shape as a whole, for example, in a cage shape.

[0014] The beam main reinforcement unit 35 includes a plurality of beam main reinforcements 91A. The beam main reinforcements 91A are embedded in the concrete portion 37. The beam main reinforcements 91A are provided so that their ends protrude from the concrete portion 37 in the extension direction of each beam 4. The beam main reinforcements 91A are each joined to a beam main reinforcement 91B of the foundation member 40 described later, and together with the beam main reinforcement 91B, form the beam main reinforcements 91A, 91B of the beam 4 as a whole. The beam main reinforcements 91A are provided at positions corresponding to the upper and lower portions of the beam 4. The beam main reinforcements 91A may be provided only in either the upper portion or the lower portion of the beam 4. The column main reinforcement unit 39 includes a plurality of column main reinforcements 93. The plurality of column main reinforcements 93 are provided so as to extend in the vertical direction. The plurality of column main reinforcements 93 are embedded in the concrete portion 37. The plurality of column main reinforcements 93 are provided so that their upper ends protrude upward from the concrete portion 37. The upper ends of the plurality of column main reinforcements 93 are joined to the main reinforcements of a column (not shown). The concrete section 37 is formed so as to embed the entire foundation reinforcement unit 33, the beam main reinforcement unit 35 and the column main reinforcement unit 39 (parts that do not protrude outward), and the pile head 2t of the foundation pile 2.

[0015] The foundation member 40 is disposed between adjacent pile foundation members 30. The foundation member 40 forms an intermediate portion of a beam 4 serving as a foundation beam provided between adjacent pile foundation members 30. The foundation member 40 is made of precast concrete and includes a concrete portion 41 formed in advance into a rectangular parallelepiped shape, a plurality of beam main reinforcements 91B, and a plurality of shear reinforcement bars 92. The concrete portion 41 is formed so that one side 41a (see FIG. 1) in a plan view has the same length as the width of the beam 4. The foundation member 40 is positioned so that the other side 41b of the concrete portion 41, which is perpendicular to the one side 41a in the horizontal plane, coincides with the extension direction of the beam 4. The concrete portion 41 is formed so that the height of the concrete portion 41 coincides with the height of the beam 4. The multiple beam main reinforcements 91B are provided at positions corresponding to the multiple beam main reinforcements 91A of the beam main reinforcement unit 35. The multiple beam main reinforcements 91B are provided, for example, at the upper and lower parts of the beam 4. The multiple beam main reinforcements 91B are embedded in the concrete portion 41, and both ends thereof protrude from the concrete portion 41 in the extension direction of the beam 4. The shear reinforcement bars 92 are provided so as to surround the multiple beam main reinforcements 91B from the outside. The upper ends of the shear reinforcement bars 92 are provided so as to protrude upward from the upper surface of the concrete portion 41. When a floor slab is formed above the concrete portion 41 that forms the beam 4, the upper end portions of the shear reinforcement bars 92 are embedded in the concrete of the floor slab.

[0016] FIG. 4 is a diagram showing a base member partially supported by a self-leveling material. As shown in FIG. 4, the concrete part 41 of the foundation member 40 is supported from below on the ground surface Gf via the self-leveling layer 7. In this embodiment, a sacrificial concrete layer 6 is laid on the ground surface Gf with a predetermined thickness in the portion other than the root cutting recess Ga. In this embodiment, as will be described later, in the portion of the ground surface Gf where the root cutting recess Ga is located, a formwork is provided to surround the pile head 2t of the foundation pile 2, and then the outside of the formwork is backfilled with a backfill material 101 such as soil and sand, and sacrificial concrete 102 is poured on the surface of the formwork, so that the sacrificial concrete 102 is integrated with the surrounding sacrificial concrete layer 6. In this way, in this embodiment, the sacrificial concrete layer 6 is also formed in the portion above the root cutting recess Ga. The self-leveling layer 7 is formed on the sacrificial concrete layer 6. The self-leveling layer 7 is formed with a self-leveling material described below so that the upper surface thereof is at a predetermined height and a predetermined horizontality. The concrete part 41 of the foundation member 40 is provided on such a self-leveling layer 7, so that the vertical height and horizontal level are adjusted.

[0017] The self-leveling layer 7 partially supports the concrete portion 41 of the foundation member 40 from below. That is, the self-leveling layer 7 is not formed to a size that contacts the entire bottom surface of the concrete portion 41, but is formed to a size that contacts only a part of the lower surface 40b of the concrete portion 41 when viewed from the top-bottom direction. The self-leveling layer 7 is formed to have a required predetermined height (predetermined layer thickness). In this embodiment, a pair of self-leveling layers 7 are provided at an interval in the extension direction of the beam 4, and support both ends of the lower surface 40b of the concrete portion 41 in the extension direction of the beam 4 from below. The self-leveling material that forms the self-leveling layer 7 will be described in detail later. Below the concrete portion 41, the gap between the pair of self-leveling layers 7 may be left as a gap, or may be filled with a filler material such as mortar (not shown). Here, in the foundation member 40 provided along the outer periphery of the building, it is preferable to fill the gap between the pair of self-leveling layers 7 below the concrete portion 41 with a filler material such as mortar. In this way, in the portion of the concrete portion 41 that is not supported by the self-leveling layers 7, the gap, the filler material such as mortar, the sacrificial concrete layer 6, and the ground surface Gf are located below, and no self-leveling material is provided.

[0018] As shown in FIG. 1, the beam portion cast-in-place concrete portion 8 is provided between the pile foundation member 30 and the foundation member 40. The beam portion cast-in-place concrete portion 8 forms a part of the beam 4 between the concrete portion 37 of the pile foundation member 30 and the concrete portion 41 of the foundation member 40. As shown in FIG. 3, the beam main reinforcement 91A of the pile foundation member 30 and the beam main reinforcement 91B of the foundation member 40 are connected by a mechanical joint 90 between the concrete portion 37 of the pile foundation member 30 and the concrete portion 41 of the foundation member 40. The beam portion cast-in-place concrete portion 8 is formed between the concrete portion 37 of the pile foundation member 30 and the concrete portion 41 of the foundation member 40 so as to cover the beam main reinforcement 91A of the pile foundation member 30, the beam main reinforcement 91B of the foundation member 40, and the mechanical joint 90. The beam portion cast-in-place concrete portion 8 is provided on the ground surface Gf or on the basing concrete layer 6. In this embodiment, since a sacrificial concrete layer 6 is provided on the ground surface Gf, the on-site poured concrete portion 8 of the beam portion is provided on the sacrificial concrete layer 6.

[0019] FIG. 5 is a cross-sectional view taken along line II-II of FIG. As shown in FIG. 1, a small beam 5 is provided between adjacent beams 4. When viewed from the top-bottom direction, the small beam 5 extends in a direction intersecting the extension direction of the beam 4. As shown in FIG. 5, the end of the small beam 5 is supported from below by a small beam support part 49 provided in a concrete part 41 of a foundation member 40 constituting a part of the beam 4. The small beam support part 49 is formed integrally with the concrete part 41 so as to protrude from the side surface of the concrete part 41 outward in the beam width direction of the beam 4. In this way, the small beam 5 is provided above the sacrificial concrete layer 6 with a gap therebetween.

[0020] Next, the self-leveling material that forms the self-leveling layer 7 will be described. Self-leveling materials are surface preparation materials that have self-flattening properties, and after application in liquid form, they spread evenly by gravity and form a flat surface. In addition, self-leveling materials harden in a relatively short time and can be used early, which allows for a reduction in application time. In the present invention, the self-leveling material forming the self-leveling layer 7 may be, for example, a material for indoor floor base preparation. When pouring the self-leveling material for indoor floor base preparation, it is preferable to adjust the amount of water in the self-leveling material in consideration of the outside air temperature, etc., and then mix it for a predetermined time to ensure fluidity within a predetermined range. This predetermined range is preferably set so that the flow value of the self-leveling material is greater than 220 mm and less than 250 mm. By ensuring the fluidity of the self-leveling material so that the flow value is sufficiently greater than 220 mm, the variation in the height of the top surface of the self-leveling layer is reduced (the difference between the maximum value and the minimum value is approximately within 1 mm), and surface cracking due to drying is suppressed. In addition, self-leveling materials used in outdoor environments are exposed to sunlight and wind immediately after pouring, and moisture evaporates more quickly than when used in indoor environments, so it is preferable to adjust and mix the material so that it spreads more quickly and over a wider area than in outdoor environments. In addition, the use of a fast-hardening self-leveling material suppresses early drying and reduces the occurrence of harmful cracks. In this embodiment, as such a self-leveling material, for example, Floor Leveler G (manufactured by Ube Industries, Ltd.) for adjusting indoor floor base is preferable. Floor Leveler G is a self-leveling material with rapid hardening properties, and according to the catalog value, the compressive strength at 7 days is 20.9 N / mm 2 , the compressive strength at 28 days is 24.2N / mm 2 and the fluidity (flow value) is 210mm±10mm.

[0021] When pouring the self-leveling material, it is preferable to apply a primer material in advance onto the basing concrete layer 6, which will be the base concrete surface of the self-leveling layer. As the primer material, for example, U Primer G (manufactured by Ube Industries, Ltd.) is preferably used. By using such a primer material, the variation (standard deviation) in the height of the top surface of the self-leveling layer 7 formed by the self-leveling material becomes extremely small. In addition, after the self-leveling material is cast, the surface of the self-leveling layer 7 is preferably cured by applying a film curing agent or covering it with a film. A film curing agent is applied to the surface of the self-leveling material to prevent moisture from escaping from the surface of the self-leveling material. Curing with a film curing agent or film can suppress cracking of the self-leveling layer 7 even when environmental conditions such as outside temperature, sunlight, and wind are particularly severe. When using a fast-hardening self-leveling material and curing the surface of the self-leveling layer after casting the self-leveling material, applying a film curing agent to the surface of the self-leveling material is more suitable from the viewpoint of workability than covering the surface of the self-leveling material with a film. As such a film curing agent, for example, Cure Keeper (manufactured by Pacific Materials Co., Ltd.) is preferably used. In this way, by using Floor Leveler G (manufactured by Ube Industries, Ltd.) as the self-leveling material and a membrane curing agent as the curing means for the self-leveling layer 7 constructed in an outdoor environment, it is possible to create a structure that can fully withstand the precast concrete foundation member 40 placed on the self-leveling layer 7. Furthermore, even if the foundation member 40 has a relatively large lower surface 40b, it can be installed on the self-leveling layer 7 while ensuring a predetermined vertical installation accuracy.

[0022] Next, a method for constructing the above-mentioned pile foundation structure 1 will be described. Fig. 6 is a flow chart showing the flow of the method for constructing the pile foundation structure according to the present embodiment. Fig. 7 is a perspective view showing a state in which a root cutting recess is formed around the foundation pile in the method for constructing the pile foundation structure according to the present embodiment. As shown in Figure 6, the method for constructing a pile foundation structure in this embodiment includes a step S11 of placing beam main reinforcement units and foundation reinforcing bar units, a step S12 of forming a self-leveling layer, a step S13 of installing foundation members on the self-leveling layer, and a step S14 of constructing a cast-in-place concrete section of the beam portion. As shown in Fig. 7, after constructing the foundation piles 2 in the ground G, the ground G around the pile heads 2t of the foundation piles 2 is excavated to form excavation recesses Ga. The pile heads 2t of each foundation pile 2 protrude upward from the bottom surface of the excavation recesses Ga. A basing concrete layer 6 is formed on the ground surface Gf in the areas other than the excavation recesses Ga. In this embodiment, the outer circumferential surface of the foundation pile 2 is formed of a steel pipe 22. In step S11 for placing the beam main reinforcement units and the foundation reinforcing bar units, first, a plurality of anchor bars 24 are welded to the outer circumferential surface of the steel pipe 22 at the pile head 2t of the foundation pile 2. Each anchor bar 24 protrudes upward from the pile head 2t.

[0023] Thereafter, a formwork (not shown) is assembled around the pile head 2t in the root cutting recess Ga. Here, the formwork may be, for example, a concrete block. Then, as shown in Fig. 3, in the root cutting recess Ga, the outside of the formwork assembled around the pile head 2t is backfilled with backfilling material 101 such as soil and sand, and sacrificial concrete 102 is poured on the surface. The sacrificial concrete 102 is integrated with the surrounding sacrificial concrete layer 6 to form a sacrificial concrete layer 6 also above the root cutting recess Ga. Note that in Fig. 7 and Fig. 8 used in the following explanation, the backfilling material 101 and sacrificial concrete 102 are not shown in order to simplify the drawings.

[0024] FIG. 8 is a perspective view showing a process of arranging beam main reinforcing bar units and foundation reinforcing bar units in the construction method for the pile foundation structure according to this embodiment. Next, as shown in Fig. 8, a rectangular parallelepiped foundation reinforcing bar unit 33, a column main reinforcing bar unit 39, and a beam main reinforcing bar unit 35 are installed above the foundation pile 2. The rectangular parallelepiped foundation reinforcing bar unit 33 is installed so as to surround the periphery of the pile head 2t. A plurality of beam main reinforcing bars 91A constituting the beam main reinforcing bar unit 35 protrudes laterally from the foundation reinforcing bar unit 33.

[0025] Fig. 9 is a perspective view showing a step of forming a self-leveling layer in the method for constructing a pile foundation structure according to the present embodiment. Fig. 10 is a perspective view showing a formwork used in the step of forming the self-leveling layer. Next, in the step S12 of forming the self-leveling layer, the self-leveling layer 7 is formed at a predetermined position on the sacrificial concrete layer 6. For this, as shown in FIG. 10, a formwork 110 is placed at a predetermined position on the sacrificial concrete layer 6. The formwork 110 is configured, for example, in a rectangular shape in a plan view. The self-leveling material as described above is poured into the formwork 110, the surface is lightly smoothed with a register or the like, and then cured for a predetermined period of time, thereby forming the self-leveling layer 7. Here, it is preferable to form a marking M1 on the inner peripheral surface of the formwork 110 in accordance with the surface height of the self-leveling layer 7 to be formed. This allows the worker to easily grasp the height of the self-leveling material without measuring the surface height one by one while pouring the self-leveling material into the formwork 110.

[0026] FIG. 11 is a perspective view showing a self-leveling layer formed in the step of forming the self-leveling layer in the method for constructing a pile foundation structure according to this embodiment. 11, the self-leveling layer 7 is preferably formed wider than the foundation member 40 in the beam width direction intersecting with the extension direction of the beam 4. In other words, the self-leveling layer 7 is preferably formed so as to protrude on both sides in the beam width direction relative to the concrete part 41 of the foundation member 40 that will be placed later on the self-leveling layer 7. Then, it is preferable to provide markings M2 on the surface of the self-leveling layer 7 thus formed in order to easily align the foundation member 40.

[0027] FIG. 12 is a perspective view showing a step of installing a foundation member on a self-leveling layer in the method for constructing a pile foundation structure according to this embodiment. In step S13 of placing a foundation member on the self-leveling layer, as shown in FIG. 12, a precast concrete foundation member 40 is placed on the self-leveling layer 7 formed at a predetermined position. The foundation member 40 is placed so that the bottom surface 40b of the concrete portion 41 contacts the two self-leveling layers 7 placed at a distance from each other. At this time, as shown in FIG. 11, the markings M2 formed on the self-leveling layer 7 are used as a guide to easily place the foundation member 40 in an appropriate position. In this way, by placing the foundation member 40 on the self-leveling layer 7, the bottom surface 40b of the precast concrete foundation member 40 is partially supported while the height is adjusted. In FIG. 12, reference character S denotes a support member for preventing the base member 40 from falling over during an earthquake and for adjusting the positional accuracy of the base member 40.

[0028] In step S14 of constructing the on-site cast concrete beam portion, first, as shown in FIG. 12, the beam main reinforcement 91A of the pile foundation member 30 and the beam main reinforcement 91B of the foundation member 40 are connected by a mechanical joint 90. Next, a formwork (not shown) is assembled so as to cover the space between the concrete portion 37 of the pile foundation member 30 and the concrete portion 41 of the foundation member 40. Then, concrete is poured on-site into the formwork to integrally construct the concrete portion 41 of the pile foundation member 30, including the lower portion of the pile foundation member 30 surrounded by the formwork such as concrete blocks in the root cutting recess Ga, and the on-site cast concrete beam portion 8 between the pile foundation member 30 and the foundation member 40. As a result, the beam main reinforcement unit 35, the foundation member 40, and the beam portion cast-in-place concrete portion 8 are connected via the beam main reinforcements 91A and 91B that are continuously installed. After that, the formwork is dismantled and removed. In this embodiment, further, as shown in Fig. 1, a sub-beam 5 is installed between adjacent beams 4. In this way, the pile foundation structure 1 is formed by the construction method of the pile foundation structure 1.

[0029] According to the pile foundation structure 1 as described above, the pile foundation structure 1 includes the foundation piles 2 and the precast concrete foundation members 40 that are installed between the foundation piles 2 to form the beams 4, the concrete pile foundation members 30 in which the beam main reinforcement units 35 that form the ends of the beams 4 and that are provided above the foundation piles 2 and the rectangular parallelepiped foundation reinforcing units 33 are embedded, a self-leveling layer 7 formed of a self-leveling material on the ground surface Gf or on the basin concrete layer 6, the precast concrete foundation members 40 that are installed on the self-leveling layer 7 and whose lower surface 40b is partially supported by the self-leveling layer 7 being adjusted in height, and a beam portion cast-in-place concrete portion 8 that is provided on the ground surface Gf or on the basin concrete layer 6 between the pile foundation members 30 and the foundation members 40, and the beam main reinforcement units 35, the foundation members 40, and the beam portion cast-in-place concrete portion 8 are connected via the beam main reinforcement units 91A and 91B that are installed continuously. According to the above-mentioned configuration, the pile foundation structure 1 includes the foundation piles 2, the pile foundation members 30 provided above the foundation piles 2, the foundation members 40 provided between the foundation piles 2 to form the beams 4, and the beam portion cast-in-place concrete portion 8 provided between the pile foundation members 30 and the foundation members 40. The beam main reinforcement units 35 of the pile foundation members 30, the foundation members 40, and the beam portion cast-in-place concrete portion 8 are connected via the beam main reinforcements 91A and 91B that are continuously installed, so that the foundation members 40 are firmly joined to the pile foundation members 30 via the beam portion cast-in-place concrete portion 8. This improves the stability of the structure, and realizes a strong pile foundation structure 1 with excellent rigidity and earthquake resistance. In such a structure, the precast concrete foundation member 40 forming the beam 4 is supported on the ground surface Gf or on the sacrificial concrete layer 6 with its height adjusted by the self-leveling layer 7 formed of a self-leveling material. After pouring the self-leveling material into the formwork 110, the material itself has self-flattening properties, and the self-leveling material spreads evenly by gravity naturally, so that a smooth surface can be easily formed. Furthermore, the self-leveling material generally dries faster than mortar. Therefore, by forming the height-adjusting member from the self-leveling material, construction can be easily performed and the construction period can be reduced compared to the case of using mortar, for example. The self-leveling layer 7 can be easily formed by providing a formwork 110 so as to surround the portion on the ground surface Gf or the sacrificial concrete layer 6 where the self-leveling layer 7 is to be formed, and pouring the self-leveling material into the formwork 110. In such an operation, even if the layer thickness of the self-leveling layer 7 is increased or its size (area) is increased slightly, the ease of construction is not easily impaired. Therefore, it is easily possible to set the predetermined height (predetermined layer thickness) and size required for the self-leveling layer 7 to a level that does not cause destruction of the ground G or the sacrificial concrete layer 6 due to punching shear force without impairing the ease of construction. Therefore, the precast concrete foundation member 40 can be reliably installed while suppressing punching shear. In particular, the underside 40b of the precast concrete foundation member 40 is partially supported by the self-leveling layer 7. In other words, the entire underside 40b of the precast concrete foundation member 40 is not supported by the self-leveling layer 7. For this reason, the size (area) of the self-leveling layer 7 can be significantly reduced compared to, for example, a case in which the precast concrete foundation member 40 has a large self-leveling layer 7 so that the entire underside 40b is supported by the self-leveling layer 7. This makes construction easier. In this way, it is possible to provide a pile foundation structure 1 in which precast concrete foundation members 40, which are placed between the foundation piles 2 to form beams 4, can be reliably installed, allowing for the construction of a sturdy structure easily in a short period of time.

[0030] The method for constructing the pile foundation structure 1 as described above is a method for constructing the pile foundation structure 1 including the foundation piles 2 and the precast concrete foundation members 40 that are installed between the foundation piles 2 to form the beams 4, and includes a step S11 of disposing the beam main reinforcement units 35 that form the ends of the beams 4 and the foundation reinforcing bar units 33 formed in a rectangular parallelepiped shape above the foundation piles 2, a step S12 of forming a self-leveling layer 7 with a self-leveling material on the ground surface Gf or the basing concrete layer 6, and a step S13 of forming a height of the self-leveling layer 7 on the self-leveling layer 7. The method includes a step S13 of installing a precast concrete foundation member 40 so that the underside 40b is partially supported while adjusting the height of the foundation member 40, and a step S14 of pouring concrete in situ to construct a cast-in-situ concrete portion 8 of the beam portion between the pile foundation member 30 in which the foundation reinforcing bar units 33 and the beam main reinforcement units 35 are buried, and the foundation member 40, wherein in the step S14 of constructing the cast-in-situ concrete portion 8 of the beam portion, the beam main reinforcement units 35, the foundation member 40, and the cast-in-situ concrete portion 8 of the beam portion are connected via the beam main reinforcements 91A, 91B which are installed in succession. According to this configuration, a pile foundation structure 1 is constructed, which includes the foundation piles 2, the pile foundation members 30 in which the foundation reinforcing bar units 33 are buried above the foundation piles 2, the foundation members 40 that are installed between the foundation piles 2 to form the beams 4, and the beam portion cast-in-place concrete portion 8 that is installed between the pile foundation members 30 and the foundation members 40. The beam main reinforcement units 35 of the pile foundation members 30, the foundation members 40, and the beam portion cast-in-place concrete portion 8 are connected via the beam main reinforcements 91A and 91B that are installed continuously, so that the foundation members 40 are firmly joined to the pile foundation members 30 via the beam portion cast-in-place concrete portion 8. This improves the stability of the structure, and a strong pile foundation structure 1 with excellent rigidity and earthquake resistance can be realized. In such a structure, the precast concrete foundation member 40 forming the beam 4 is supported on the ground surface Gf or on the sacrificial concrete layer 6 with its height adjusted by the self-leveling layer 7 formed of a self-leveling material. After pouring the self-leveling material into the formwork 110, the material itself has self-flattening properties, and the self-leveling material spreads evenly by gravity naturally, so that a smooth surface can be easily formed. Furthermore, the self-leveling material generally dries faster than mortar. Therefore, by forming the height-adjusting member from the self-leveling material, construction can be easily performed and the construction period can be reduced compared to the case of using mortar, for example. The self-leveling layer 7 can be easily formed by providing a formwork 110 so as to surround the portion on the ground surface Gf or the basin concrete layer 6 where the self-leveling layer 7 is to be formed, and pouring the self-leveling material into the formwork 110. In such an operation, even if the layer thickness of the self-leveling layer 7 is increased or its size (area) is increased slightly, the ease of construction is not easily impaired. Therefore, it is easily possible to set the predetermined height (predetermined layer thickness) and size required for the self-leveling layer 7 to a level where the ground G or the basin concrete is not destroyed by punching shear force without impairing the ease of construction. Therefore, the precast concrete foundation member 40 can be reliably installed while suppressing punching shear. In particular, when constructing the above-mentioned pile foundation structure 1, the underside 40b of the precast concrete foundation member 40 is partially supported by the self-leveling layer 7. In other words, the entire underside 40b of the precast concrete foundation member 40 is not supported by the self-leveling layer 7. For this reason, the size (area) of the self-leveling layer 7 can be significantly reduced compared to, for example, a case in which the precast concrete foundation member 40 has a large self-leveling layer 7 so that the entire underside 40b is supported by the self-leveling layer 7. This makes construction easier. In this way, it is possible to realize a pile foundation structure 1 in which the precast concrete foundation members 40, which are placed between the foundation piles 2 to form the beams 4, can be securely installed, allowing for the construction of a sturdy structure easily in a short period of time.

[0031] Moreover, in the construction method of the pile foundation structure 1, the foundation member 40 is supported by the self-leveling layer 7 at both end sides in the extension direction of the beam 4. According to this configuration, in the precast concrete foundation member 40 forming the beam 4, both end sides in the extension direction of the beam 4 are supported by the self-leveling layer 7, so that the precast concrete foundation member 40 can be positioned and fixed at a uniform height. Therefore, in the foundation member 40 of the present invention, both end sides in the extension direction of the beam 4 are supported by the self-leveling layer 7, so that the size (area) of the self-leveling layer 7 can be significantly reduced compared to the case where the self-leveling layer 7 is provided on the entire surface of the underside 40b of the beam 4. This makes construction easier.

[0032] (Modification of the embodiment) In the above embodiment, both end sides of the base member 40 in the extension direction of the beam 4 are supported by the self-leveling layer 7, but this is not limiting. As shown in FIG. 13, the base member 40 may be configured so that the central portion side in the extension direction of the beam 4 is supported by a self-leveling layer 7. According to this configuration, the precast concrete foundation member 40 forming the beam 4 is supported at the center side in the extension direction of the beam 4 by the self-leveling layer 7, so that the entire bottom surface 40b of the beam 4 is supported by the self-leveling layer 7. This makes it possible to significantly reduce the size (area) of the self-leveling layer 7 compared to a case in which the self-leveling layer 7 is provided large so that the entire bottom surface 40b of the beam 4 is supported by the self-leveling layer 7. This makes construction easier.

[0033] The pile foundation structure and the method for constructing the pile foundation structure of the present invention are not limited to the above-mentioned embodiments and modified examples described with reference to the drawings, and various other modified examples are contemplated within the technical scope. For example, in the above embodiment, the self-leveling layer 7 is provided on the sacrificial concrete layer 6 formed on the ground surface Gf, but this is not limiting, and the self-leveling layer 7 may be formed directly on the ground surface Gf. Similarly, in the above embodiment, the on-site cast concrete portion 8 of the beam portion is provided on the sacrificial concrete layer 6, but this is not limiting, and it may be formed directly on the ground surface Gf. In the above embodiment, the pile foundation structure includes the column main reinforcement units 39, but is not limited to this. The pile foundation structure may be configured not to include the column main reinforcement units 39, and the top surface of the footing 3 may be formed smooth, and a seismic isolation device may be provided on the footing 3.

[0034] In the above embodiment, the beam main reinforcement units 35 and the foundation reinforcement units 33 are formed by directly arranging rebars on-site and concrete is poured to bury them, but this is not limited to the above. For example, a part of the concrete member including the beam main reinforcement units 35 and the foundation reinforcement units 33 may be manufactured as precast concrete, and the beam main reinforcement units 35 and the foundation reinforcement units 33 may be constructed by installing the precast concrete on-site. In this case, for example, a method for constructing a pile foundation structure includes foundation piles and precast concrete foundation members that are installed between the foundation piles to form beams, and includes the steps of: providing a pile foundation member that is partially or entirely formed of precast concrete and that has beam main reinforcement units that form the ends of the beams and foundation reinforcing bars formed in a rectangular parallelepiped shape buried above the foundation piles; forming a self-leveling layer portion with a self-leveling material on the ground surface or on a basin concrete layer; installing a precast concrete foundation member on the self-leveling layer so that its underside is partially supported while its height is adjusted by the self-leveling layer; and pouring concrete on site to construct a cast-in-site concrete beam portion between the pile foundation member and the foundation member, and the step of constructing the cast-in-site concrete beam portion is characterized in that the beam main reinforcement units, the foundation member, and the cast-in-site concrete beam portion are connected via the beam main reinforcement units that are installed in succession. Needless to say, even in such a case, the same effects as those of the above embodiment can be achieved.

[0035] In addition, the configurations described in the above embodiments can be selected or changed as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0036] 1 Pile foundation structure 33 Foundation reinforcement unit 2 Foundation pile 35 Beam main reinforcement unit 4 Beams 40 Foundation members 6. Sacrificial concrete layer 40b Bottom surface of foundation member 7 Self-leveling layer 91A, 91B Beam main bar 8 Beam part of cast-in-place concrete Gf Ground surface 30 Pile foundation member M1, M2 marking

Claims

1. A pile foundation structure comprising foundation piles and precast concrete foundation members installed between the foundation piles to form beams, The foundation pile; The pile foundation member is made of concrete and has a beam main reinforcing unit that forms the end of the beam and a foundation reinforcing unit formed in a rectangular parallelepiped shape, which is provided above the foundation pile; a self-leveling layer formed of a self-leveling material on the ground surface or on the basin concrete layer; The foundation member is made of precast concrete and is installed on the self-leveling layer, and the height of the foundation member is adjusted by the self-leveling layer, and the bottom surface of the foundation member is partially supported by the self-leveling layer. A beam portion on-site poured concrete portion provided on the ground surface or the sacrificial concrete layer between the pile foundation member and the foundation member; Equipped with A pile foundation structure characterized in that the beam main reinforcement unit, the foundation member, and the on-site poured concrete portion of the beam portion are connected via beam main reinforcement bars installed continuously.

2. A method for constructing a pile foundation structure comprising foundation piles and precast concrete foundation members installed between the foundation piles to form beams, comprising: A step of disposing a beam main reinforcing unit forming an end portion of the beam and a foundation reinforcing bar unit formed in a rectangular parallelepiped shape above the foundation pile; forming a self-leveling layer on the ground surface or on the sacrificial concrete layer using a self-leveling material; a step of installing the precast concrete foundation member on the self-leveling layer so that the lower surface of the foundation member is partially supported by the self-leveling layer while adjusting the height; A step of constructing a beam portion cast-in-place concrete part between a pile foundation member in which the foundation reinforcing bar unit and the beam main reinforcing bar unit are embedded and the foundation member by casting concrete on site; Including, A method for constructing a pile foundation structure, characterized in that in the process of constructing the on-site poured concrete section of the beam portion, the beam main reinforcement unit, the foundation member, and the on-site poured concrete section of the beam portion are connected via beam main reinforcement that is installed in succession.

3. A method for constructing a pile foundation structure comprising foundation piles and precast concrete foundation members installed between the foundation piles to form beams, comprising: A step of providing a pile foundation member formed as a part or whole of a precast concrete structure, in which a beam main reinforcing unit forming the end of the beam and a foundation reinforcing unit formed in a rectangular parallelepiped shape are embedded above the foundation pile; forming a self-leveling layer on the ground surface or on the sacrificial concrete layer using a self-leveling material; a step of installing the precast concrete foundation member on the self-leveling layer so that the lower surface of the foundation member is partially supported by the self-leveling layer while adjusting the height; A step of constructing a beam portion in-situ concrete portion between the pile foundation member and the foundation member by pouring concrete in-situ; Including, A method for constructing a pile foundation structure, characterized in that in the process of constructing the on-site poured concrete section of the beam portion, the beam main reinforcement unit, the foundation member, and the on-site poured concrete section of the beam portion are connected via beam main reinforcement that is installed in succession.

4. The base member is Both end sides of the beam in the extension direction are supported by the self-leveling layer, or The central portion of the beam in the extension direction is supported by the self-leveling layer. A method for constructing a pile foundation structure according to claim 2 or 3.

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