Prefabricated SRC piles and methods for manufacturing prefabricated SRC piles

Abstract

To provide an existing SRC pile and a manufacturing method of an existing SRC pile which surely incorporate a reinforcement into an SC pile and achieve an organically integrated structure, thereby can further increase an allowable bending moment and allowable shear force, and can greatly improve bending deformation performance and axial force holding performance with a high axial force.SOLUTION: An existing SRC pile has a steel pipe 1, an upper end plate 2 and a lower end plate 3 fixed to upper and lower ends of the steel pipe 1, a concrete part 4 which is formed over the full length of the steel pipe 1 between the upper end plate 2 and the lower end plate 3 and has a hollow part 4a, a hoop reinforcement 5 such as a spiral reinforcement 5 which is incorporated in the concrete part 4, and a plurality of reinforcements 6 which are fixed to the hoop reinforcement 5, and are provided at almost concentric arrangement relative to the steel pipe 1. The upper and lower ends of the reinforcement 1 are fixed to the upper end plate 2 and the lower end plate 3.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] This invention belongs to the technical field of a so-called prefabricated SRC pile (reinforced concrete pile with outer steel pipe), which is formed by incorporating steel bars into a conventional SC pile (concrete pile with outer steel pipe). In this specification, among the terms of "prefabricated SRC pile", "prefabricated" refers to a prefabricated product that is manufactured in a factory or the like in advance and transported to the site, and is used to clearly distinguish it from a pile (cast-in-place concrete pile) that is constructed by casting concrete on site. Also, "SRC pile" refers to an SC pile in which steel bars (steel bar units) are incorporated (embedded) in concrete.

Background Art

[0002] Among prefabricated piles, there are SC piles, RC piles, PHC piles, PRC piles, etc., but there is no so-called prefabricated SRC pile in which steel bars are arranged inside the concrete of the SC pile. For reference, although there is a description that can be regarded as a prefabricated SRC pile in the second line from the bottom of paragraph

[0011] of Patent Document 1 or in lines 21 - 22 of the left column on page 2 of Patent Document 2, considering the context before and after, it is natural to interpret it as a mere misdescription of a PRC pile.

[0003] Among the prefabricated piles, the SC pile, compared with a prefabricated concrete pile, has a structure in which the outer peripheral surface of the concrete pile is covered with a steel pipe and integrated, and thus has strength advantages such as being able to increase the allowable bending moment and allowable shear force due to the synergistic effect between the steel pipe and the concrete, and its demand has been increasing in recent years.

[0004] However, although the SC pile has no steel bars and the concrete is protected by the steel pipe, in fact, under high axial force, the concrete inside the steel pipe is destroyed and the axial force cannot be maintained. Therefore, it is substantially equivalent to a structure with only a steel pipe, and there are problems to be improved such as the synergistic effect between the steel pipe and the concrete cannot be obtained over time.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-197061 [Patent Document 2] Japanese Patent Application Publication No. 4-169621 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] If it were possible to reliably incorporate reinforcing bars into the aforementioned SC pile and create an organically integrated structure, it would clearly be more beneficial than an SC pile without reinforcing bars, as it would allow for even greater allowable bending moment and allowable shear force.

[0007] Therefore, the present invention was devised in view of the problems of the background technology described above, and its objective is to provide a ready-made SRC pile and a method for manufacturing a ready-made SRC pile, which can further increase the allowable bending moment and allowable shear force, and can also greatly improve bending deformation performance and axial force holding performance at high axial forces, by realizing a structure in which reinforcing bars are reliably incorporated into the SC pile and organically integrated. [Means for solving the problem]

[0008] As a means to solve the above problem, the ready-made SRC pile according to the invention described in claim 1 is made of a steel pipe and An upper end plate and a lower end plate are fixed to the upper and lower ends of the steel pipe, A concrete section having a hollow portion formed along the entire length of the steel pipe between the upper and lower end plates, The aforementioned concrete section contains hoop reinforcement such as spiral reinforcement, It is fixed to the aforementioned hoop reinforcement and is arranged in a substantially concentric circular manner with respect to the steel pipe. The upper and lower ends are fixed to the upper end plate and the lower end plate. Multiple reinforcing bars, possess already SRC piles manufactured by And, The reinforcing bar is fixed to the inside or outside of the hoop reinforcement by welding or binding material such as iron wire, and is fixed to a shape-retaining member that is annular in shape, slightly smaller or slightly larger than the hoop reinforcement when viewed from the planar direction, and spiral in shape when viewed from the vertical direction, so that it is positioned and fixed between the shape-retaining member and the hoop reinforcement so as to be directly restrained by the shape-retaining member and the hoop reinforcement.

[0011] Claim 2 The invention described in the claims 1 In the prefabricated SRC pile described above, a separator is provided in the hoop reinforcement to maintain a constant distance between the steel pipe and the reinforcing bar.

[0012] Claim 3 The invention described in the claims 1 In the prefabricated SRC pile described above, a separator is provided on the shape-retaining member to maintain a constant distance between the steel pipe and the reinforcing bar.

[0013] Claim 4 The method for manufacturing a ready-made SRC pile according to the invention described above comprises the steps of constructing a reinforcing bar unit in which multiple reinforcing bars are arranged in a substantially concentric circular pattern inside or outside a hoop reinforcing bar such as a spiral reinforcing bar, The reinforcing bar unit is placed inside the steel pipe such that the reinforcing bars of the unit are positioned approximately concentrically with respect to the steel pipe. The process, The reinforcing bar is welded to the inside or outside of the hoop reinforcement, or fixed with binding material such as iron wire, and is fixed to a shape-retaining member that is annular in shape, slightly smaller or slightly larger than the hoop reinforcement when viewed from the planar direction, and spiral in shape when viewed from the vertical direction, so that it is positioned and fixed between the shape-retaining member and the hoop reinforcement so that it is directly restrained by the shape-retaining member and the hoop reinforcement, and the upper and lower ends of the reinforcing bar are provided so that they can be fixed to the upper and lower end plates that are fixed to the upper and lower ends of the steel pipe, The upper and lower end plates are fixed to the upper and lower ends of the steel pipe. This involves the process of fixing the upper and lower ends of the reinforcing bar to the upper and lower end plates, The method is characterized by manufacturing an SC pile containing the reinforcing bar unit by injecting concrete into the steel pipe and centrifuging it.

[0016] Claim 5 The invention described in the claims 4 The method for manufacturing a prefabricated SRC pile as described above is characterized by providing a separator in the hoop reinforcement to maintain a constant distance between the steel pipe and the reinforcing bar, and then injecting the concrete.

[0017] Claim 6 The invention described in the claims 4 The method for manufacturing a prefabricated SRC pile as described above is characterized in that a separator is provided in the shape-retaining member to maintain a constant distance between the steel pipe and the reinforcing bar, and then the concrete is injected. [Effects of the Invention]

[0018] According to the prefabricated SRC pile and the manufacturing method of the prefabricated SRC pile according to the present invention, the following effects can be obtained. Since the reinforcing bars are surely incorporated into the SC pile and exhibit an organically integrated structure, the allowable bending moment and the allowable shearing force described above can be further increased, and the bending deformation performance and the axial force holding performance at a high axial force can be greatly improved. Therefore, a prefabricated SRC pile having very excellent strength and rigidity can be realized as compared with the prefabricated SC pile.

Brief Description of the Drawings

[0019] [Figure 1] A is an elevation view showing a prefabricated SRC pile (SC pile provided with a reinforcing bar unit) according to the present invention, and B is a plan view thereof. [Figure 2] It is an enlarged view of FIG. 1B. [Figure 3] It is an enlarged cross-sectional view of the X-X portion of FIG. 1A. [Figure 4] It is an enlarged cross-sectional view of the Y-Y portion of FIG. 1A. [Figure 5] It is an enlarged cross-sectional view in the direction of the Z-Z arrow of FIG. 1A. [Figure 6] It is a vertical cross-sectional view schematically showing an application example of the prefabricated SRC pile according to the present invention.

Modes for Carrying Out the Invention

[0020] Next, an example of the prefabricated SRC pile and the manufacturing method of the prefabricated SRC pile according to the present invention will be described based on the drawings.

[0021] As shown in FIGS. 1 to 6, the prefabricated SRC pile 10 according to the present invention includes a steel pipe 1, an upper end plate 2 and a lower end plate 3 fixed to the upper and lower ends of the steel pipe 1, a concrete portion 4 having a hollow portion 4a formed over the entire length of the steel pipe 1 between the upper end plate 2 and the lower end plate 3, hoop bars 5 such as spiral bars 5 incorporated in the concrete portion 4, and a plurality of reinforcing bars 6 fixed to the hoop bars 5 and provided in a substantially concentric arrangement with respect to the steel pipe 1.

[0022] The steel pipe 1 has no particular size restrictions, but commercially available products with an outer diameter (D) of approximately 600 to 1600 mm, a thickness (t) of approximately 9 to 25 mm, and a length (L) of approximately 5 to 15 m are preferably used. The length of the steel pipe 1 is such that it can effectively resist the form of the structure supported by the prefabricated SRC pile 10 according to the present invention, or the horizontal forces (bending stress and shear stress) acting on the structure. As a guideline, it is preferable that the length be about five times the pile diameter, but this may be appropriately modified depending on the properties of the ground 6. In this embodiment, the upper end plate 2 and the lower end plate 2 are formed in the shape and size of rings. In this embodiment, spiral muscle 5 is used as hoop muscle 5, but the same procedure can be performed with conventional tie muscles.

[0023] The aforementioned reinforcing bars 6 are ordinary reinforcing bars commonly used as reinforcement in building structures. In other words, PC steel materials such as PC steel bars embedded in PHC piles are not used. The reinforcing bars 6 are arranged in the axial direction of the pipe and are welded to the hoop reinforcement bars 5 or fixed to them with binding materials such as iron wire. In this embodiment, 16 reinforcing bars 6 are arranged in a nearly concentric circular pattern with respect to the steel pipe 1, and are balanced at positions that divide the circumference into approximately 16 equal parts. However, the number of reinforcing bars 6 is not limited to 16 and can be increased or decreased as appropriate depending on the structural design. Nevertheless, it is common to use a range of 8 to 22 bars.

[0024] Next, a method for manufacturing the prefabricated SRC pile 10 according to the present invention will be described. It should be noted that the method described below is merely one example. In other words, the manufacturing method for the pre-fabricated SRC pile 10 involves welding multiple (16) reinforcing bars 6 to the inside (or outside) of a spiral reinforcement bar 5 (or other hoop reinforcement bar) in advance, and then arranging them in a nearly concentric circular pattern using joining means such as binding materials to construct a reinforcement bar unit (5, 6). Next, the reinforcing bar units (5, 6) are placed inside the steel pipe 1 such that the reinforcing bars 6 of the reinforcing bar units (5, 6) are positioned approximately concentrically with respect to the steel pipe 1. Next, the upper end plate 2 and the lower end plate 3 are fixed to the upper and lower ends of the steel pipe 1. Subsequently, with the steel pipe 1 lying horizontally, concrete 4 is injected into the steel pipe 1 and centrifugal molding is performed. After curing, a concrete section 4 having a hollow section 4a corresponding to the inner diameter of the upper end plate 2 and the lower end plate 3 is formed inside the steel pipe 1, thereby manufacturing an SC pile with the reinforcing bar units (5, 6) built in, i.e., a pre-fabricated SRC pile 10.

[0025] Therefore, according to the prefabricated SRC pile and the method for manufacturing the prefabricated SRC pile according to the present invention, the reinforcing bar unit (hoop reinforcement 5 and reinforcing bar 6) is not only securely fixed (attached) to the concrete part 4 by centrifugal molding, but the prefabricated SRC pile 10 has a structure in which the concrete part 4 containing the reinforcing bar unit is securely fixed to the steel pipe 1, so to speak, the prefabricated SRC pile 10 has a structure in which the reinforcing bars (reinforcing bar units 5 and 6) are securely incorporated into the SC pile and organically integrated, so that the allowable bending moment and allowable shear force can be further increased, and the bending deformation performance and axial force holding performance at high axial force can be greatly improved. Thus, it is possible to realize a prefabricated SRC pile 10 with superior strength and rigidity compared to a prefabricated SC pile.

[0026] In this embodiment, the upper and lower ends of the reinforcing bar 6 are fixed to the upper end plate 2 and the lower end plate 3, respectively. There are various fixing means, such as screw connections and welded connections, but in this embodiment, as shown in Figure 3 (or Figure 4), the upper end (or lower end) of the reinforcing bar 6 is enlarged by attaching an enlarged (tapered) fixing device, and the through hole formed in the corresponding upper end plate 2 (or lower end plate 3) is made stepped (tapered), thereby fixing the upper end (or lower end) of the reinforcing bar 6 that has passed through the through hole in a way that prevents it from being pulled out. Therefore, by fixing the upper and lower ends of the reinforcing bar 6 to the upper end plate 2 and the lower end plate 3, respectively, the unity between the reinforcing bar 6 and the steel pipe 1 can be further enhanced. As a result, the manufactured prefabricated SRC pile 10 can have an even larger allowable bending moment and allowable shear force, and its bending deformation performance and axial force holding performance at high axial forces can be greatly improved. Consequently, a prefabricated SRC pile 10 with significantly superior strength and rigidity compared to a prefabricated SC pile can be realized.

[0027] In this embodiment, the reinforcing bar 6 is positioned and fixed so as to be constrained between the spiral reinforcing bar (hoop reinforcing bar) 5 and a shape-retaining member 7 that is slightly smaller than the spiral reinforcing bar 5 when viewed from the plan direction (spiral-shaped when viewed from the vertical direction). The shape-retaining member 7 is attached to the reinforcing bar 6 by welding or by binding material such as iron wire. Therefore, by restraining the reinforcing bar 6 with internal and external restraining members (5, 7) when viewed from the planar direction, the unity between the reinforcing bar 6 and the spiral reinforcement 5 can be further enhanced. Furthermore, since the shape-retaining member 7 itself exhibits a reinforcement unit (5, 6, 7) structure that also serves as reinforcing reinforcement, the manufactured prefabricated SRC pile 10 can have an even larger allowable bending moment and allowable shear force, and its bending deformation performance and axial force holding performance at high axial forces can be greatly improved. Consequently, a prefabricated SRC pile 10 with significantly superior strength and rigidity compared to a prefabricated SC pile can be realized. Note that the relative positions of the inner and outer restraining members (5, 7) sandwiching the reinforcing bar 6 may be reversed. That is, the reinforcing bar 6 can be positioned and fixed on the outside of the spiral reinforcement bar 5, and, when viewed from a planar direction, restrained between the spiral reinforcement bar 5 and an annular shape-retaining member 7 that is slightly larger than the spiral reinforcement bar 5.

[0028] Furthermore, in this embodiment, a separator 8 that maintains a constant distance between the steel pipe 1 and the reinforcing bar 5 is provided on the shape-retaining member 8 by joining means such as welding. The separator 8 can also be provided on the spiral reinforcement (hoop reinforcement) 5 by joining means such as welding. Therefore, by providing a separator 8 on the shape-retaining member 8 or spiral reinforcement 5 to maintain a constant distance between the steel pipe 1 and the reinforcing bar 5, centrifugal molding can be performed while maintaining a more appropriate distance. As a result, the manufactured prefabricated SRC pile 10 has excellent quality, and the allowable bending moment and allowable shear force can be further increased. Furthermore, the bending deformation performance and axial force holding performance at high axial forces can be greatly improved. Consequently, it is possible to realize a prefabricated SRC pile 10 with significantly superior strength and rigidity compared to a prefabricated SC pile.

[0029] Although embodiments have been described above based on the drawings, it should be noted that the present invention is not limited to the illustrated examples and includes design modifications and variations in application that are ordinarily performed by those skilled in the art, without departing from the technical concept. For reference, Figure 6 shows an example of the application of a prefabricated SRC pile 10 according to the present invention. One or more pile bodies 11 (for example, the aforementioned SRC pile 10, PHC pile, PRC pile, etc.) are first joined together and embedded so that the pile tip reaches the supporting layer 12 in the ground, or, even if it does not reach the supporting layer 12, so as to be long enough to obtain the necessary frictional force with the soil layer. The pile bodies 11 are joined to each other by welding of the end plates or by mechanical joints. However, if the supporting layer 12 is shallow, or if the necessary frictional bearing force can be obtained, only the prefabricated SRC pile 10 according to the present invention may be embedded and used. After embedding as described above, multiple whisker bars 9 are attached vertically upward to the upper end of the outer circumference of the prefabricated SRC pile 10, and the whisker bars 9 are used to integrate it with a structure 13 such as a foundation. For this reason, the pile head is usually left to protrude above the ground surface by about half of the pile's outer diameter. [Explanation of Symbols]

[0030] 1 Steel pipe 2 Upper end plate 3 Lower end plate 4. Concrete section 4a Hollow part 5. Spiral muscles (hoop muscles) 6 Reinforcement bars 7 Shape-retaining member 8 Separators 9 Beard bars 10 Prefabricated SRC piles 11 Pile body 12 Support layer 13 Foundations and other structures

Claims

1. Steel pipes and An upper end plate and a lower end plate are fixed to the upper and lower ends of the steel pipe, A concrete section having a hollow portion formed along the entire length of the steel pipe between the upper and lower end plates, The aforementioned concrete section contains hoop reinforcement such as spiral reinforcement, Multiple reinforcing bars are fixed to the hoop reinforcement, arranged in a substantially concentric circular pattern with respect to the steel pipe, and their upper and lower ends are fixed to the upper and lower end plates, A prefabricated SRC pile having, A prefabricated SRC pile characterized in that the reinforcing bar is welded to the inside or outside of the hoop reinforcement, or fixed with binding material such as iron wire, and is welded to or fixed with binding material such as iron wire to a shape-retaining member that is annular in shape, slightly smaller or slightly larger than the hoop reinforcement when viewed from the plan direction, and spiral in shape when viewed from the vertical direction, thereby positioning and fixing the reinforcing bar so as to be directly restrained between the shape-retaining member and the hoop reinforcement.

2. A prefabricated SRC pile according to claim 1, characterized in that a separator is provided in the hoop reinforcement to maintain a constant distance between the steel pipe and the reinforcing bar.

3. A prefabricated SRC pile according to claim 1, characterized in that a separator is provided on the shape-retaining member to maintain a constant distance between the steel pipe and the reinforcing bar.

4. A process for constructing a reinforced concrete unit, which consists of multiple reinforcing bars arranged in a nearly concentric circular pattern inside or outside a hoop reinforcement such as a spiral reinforcement, A step of arranging the reinforcing bar unit inside the steel pipe such that the reinforcing bars of the reinforcing bar unit are positioned substantially concentrically with respect to the steel pipe, The reinforcing bar is welded to the inside or outside of the hoop reinforcement, or fixed with binding material such as iron wire, and is fixed to a shape-retaining member that is annular in shape, slightly smaller or slightly larger than the hoop reinforcement when viewed from the planar direction, and spiral in shape when viewed from the vertical direction, so that it is positioned and fixed between the shape-retaining member and the hoop reinforcement so that it is directly restrained by the shape-retaining member and the hoop reinforcement, and the upper and lower ends of the reinforcing bar are provided so that they can be fixed to the upper and lower end plates that are fixed to the upper and lower ends of the steel pipe, The process involves fixing the upper and lower ends of the reinforcing bars to the upper and lower end plates by fixing the upper and lower end plates to the upper and lower end plates of the steel pipe, A method for manufacturing a prefabricated SRC pile, characterized by manufacturing an SC pile containing the reinforcing bar unit by injecting concrete into the steel pipe and centrifuging it.

5. A method for manufacturing a prefabricated SRC pile according to claim 4, characterized in that a separator is provided in the hoop reinforcement to maintain a constant distance between the steel pipe and the reinforcing bar, and then concrete is injected.

6. A method for manufacturing a prefabricated SRC pile according to claim 4, characterized in that a separator is provided in the shape-retaining member to maintain a constant distance between the steel pipe and the reinforcing bar, and then concrete is injected.

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