Precast foundation structure and construction method for precast foundation structure

Abstract

To provide a precast foundation structure capable of avoiding interference of main reinforcing bars in connection with precast foundations on both sides already laid at the last laying point.SOLUTION: A precast foundation structure includes at least a corner precast foundation 1 laid at a specific corner location, and corner adjacent precast foundations 2 and 3 laid adjacent to this corner precast foundation 1. The foundation 1 has a joint surface 11 on one end side and a joint surface 12 on the other end side, and has a buried pipe portion 13 that leads from the joint surface 12 side to the outer surface facing back to the joint surface 12. The joint surface 11 side of the foundation 1 and the joint surface side of the foundation 2 are connected by a main reinforcing bar. A insertion reinforcing bar 14 inserted into the buried pipe portion 13 from an outer surface of the foundation 1 is connected to a joint portion 38 buried in the joint surface side of the foundation 3 that is joined to the joint surface 12 side of the foundation 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a precast foundation structure in which a reinforced concrete foundation is precast and a construction method of the precast foundation structure.

Background Art

[0002] A construction method of assembling a precast foundation in which a reinforced concrete foundation is precast at a construction site is known. In this construction method, in order to absorb the manufacturing error of the precast member and the construction error at the construction site, a vertical joint is formed by leaving a gap between the joint surfaces of the precast member. Further, in the case of a reinforced concrete structure, for stress transmission, the reinforcing bars (main reinforcing bars) of the precast foundation are joint-connected at the vertical joint. As this joint connection, when using a mechanical joint embedded on the joint surface side of one precast member, grout is filled into the joint member inside of this mechanical joint and at the same time grout is also filled between the joint surfaces.

[0003] As an example, as shown in FIG. 5, the precast foundation 8 constituting the mat foundation has a structure in which the main reinforcing bar 81 protrudes from one joint surface side and a mechanical joint 82 into which the main reinforcing bar 81 is inserted is provided on the other joint surface side.

[0004] In Patent Document 1, a PC joint member constituting a joint portion is provided with a reinforcing bar accommodating hole that opens to the member end surface and a fixing hardware embedded at the end of the reinforcing bar accommodating hole, and a PC beam member in which a reinforcing bar insertion hole of a mechanical joint connected to the beam main reinforcing bar opens to the member end surface is built in, and a reinforcing bar having a thread on the outer peripheral surface is screwed with a through hole of the fixing hardware, and the reinforcement is arranged so that the tip reaches inside the mechanical joint of the PC beam member, a nut is tightened from the end side of the reinforcing bar, grout is filled until it overflows between the nut and the reinforcing bar, and a construction method of filling grout into the mechanical joint of the PC beam member and the reinforcing bar accommodating hole is disclosed.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-293192 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the foundation structure shown in Figure 5, at the locations where the last precast foundation 8A is laid (two locations in Figure 5), interference of the main reinforcement occurs between it and the existing adjacent precast foundation 8. Therefore, the specifications of the last precast foundation 8A to be laid must be changed from those of the other precast foundations 8. Furthermore, the anchorage conditions for the connection of the main reinforcement must be met in this modified specification.

[0007] The present invention aims to provide a precast foundation structure and a construction method for a precast foundation structure that can avoid interference between the main reinforcement bars when joining them with precast foundations already laid on either side at the final laying point, and also eliminate the need to satisfy anchoring conditions when connecting the main reinforcement bars. [Means for solving the problem]

[0008] The precast foundation structure of this invention comprises at least a corner precast foundation laid at a specific corner location, and a corner-adjacent precast foundation laid adjacent to the corner precast foundation. The above-mentioned corner precast foundation has a first joint surface on one end and a second joint surface on the other end, and also has a buried pipe section that extends from the second joint surface side to the outer surface facing away from the second joint surface. The precast foundation for the corner mentioned above and the precast foundation adjacent to the corner, which is joined to the first joint surface side, are joined by main reinforcement bars, A joint portion is embedded in the joint surface side of the corner-adjacent precast foundation that is joined to the second joint surface side of the corner precast foundation, and the reinforcing bars inserted into the embedded pipe portion from the outer surface of the corner precast foundation are connected to this joint portion, and the embedded pipe portion is filled with grout.

[0009] With the above configuration, the corner precast foundation is connected by inserting reinforcing bars into the buried pipe section. Therefore, by using this corner precast foundation as the last to be laid, interference between the main reinforcing bars and the already laid adjacent precast foundations can be avoided. Furthermore, the reinforcing bars inserted into the buried pipe section of the corner precast foundation do not function as main reinforcing bars that bear shear strength, but rather as anti-slip members that suppress displacement of the corner precast foundation. Therefore, it is not necessary to satisfy the anchorage conditions for connecting the main reinforcing bars.

[0010] The inserted reinforcing bar has a male threaded portion, and the joint portion has a female threaded portion exposed on the joining surface side, and the male threaded portion of the inserted reinforcing bar may be screwed into the female threaded portion. This allows the inserted reinforcing bar to be connected to the joint portion by screw fastening. Grout is filled into the buried pipe portion.

[0011] At a minimum, the second joint surface of the corner precast foundation may have a recess formed in a direction perpendicular to the joint surface, into which grout material is filled. This allows the grout material hardened in the recess to receive loads in the direction perpendicular to the joint surface, thereby increasing the restraining force against displacement of the corner precast foundation relative to the corner-adjacent precast foundation.

[0012] The above-mentioned precast corner foundation has a foundation beam section and a footing section that extends laterally from the lower part of the foundation beam section. In a plan view, the footing section has a first side and a second side that are perpendicular to each other, the foundation beam section is L-shaped, the first joint surface may be located substantially flush with the first side, and the second joint surface may be located substantially flush with the second side.

[0013] The construction method for the precast foundation structure of this invention is a method for constructing the precast foundation structure described in any of the above, characterized in that the laying starts with the corner-adjacent precast foundation that is joined to the first joint surface side or the second joint surface side of the corner precast foundation, and after laying the corner-adjacent precast foundation that is joined to the second joint surface side or the first joint surface side of the corner precast foundation, the corner precast foundation is laid last.

[0014] With this method, the corner precast foundation is connected by inserting reinforcing bars into the buried pipe section. Therefore, by using this corner precast foundation at the final laying point, interference between the main reinforcing bars and the already laid adjacent precast foundations can be avoided. Furthermore, the reinforcing bars inserted into the buried pipe section of the corner precast foundation function not as beam main reinforcement, but as anti-slip members that suppress displacement of the corner precast foundation. This eliminates the need to satisfy anchorage conditions when connecting the main reinforcing bars.

[0015] Furthermore, the construction method for the precast foundation structure of this invention is a method for constructing the precast foundation structure described in any of the above, wherein the number of corner precast foundations is multiple in one enclosed foundation section, and the laying is started from the corner adjacent precast foundation joined to the first joint surface side or the second joint surface side of one of the multiple corner precast foundations, and if it is not possible to lay other precast foundations connected to the corner adjacent precast foundation, the laying of the corner adjacent precast foundation joined to the first joint surface side or the second joint surface side of another corner precast foundation and the laying of other precast foundations connected to this corner adjacent precast foundation are performed.

[0016] With this method, if it is not possible to lay other precast foundations connected to the aforementioned corner-adjacent precast foundation, the aforementioned corner-adjacent precast foundation, which is joined to the joint surface side of another corner precast foundation, and the laying of other precast foundations connected to this corner-adjacent precast foundation will be carried out, thus avoiding a situation where foundation work is stopped.

[0017] Furthermore, the construction method for the precast foundation structure of this invention is a method for constructing the precast foundation structure described in any of the above, wherein the number of corner precast foundations is multiple in one enclosed foundation section, and for all or part of the extended portion of these multiple corner precast foundations, the laying is started from the corner adjacent precast foundation that is joined to the first joint surface side or the second joint surface side of the corner precast foundation, and after laying the corner adjacent precast foundation that is joined to the second joint surface side or the first joint surface side of the corner precast foundation, the corner precast foundation is laid last in each extended portion.

[0018] This method allows for the simultaneous construction of all or part of the extended sections of multiple corner precast foundations. [Effects of the Invention]

[0019] In the present invention, it is possible to avoid a situation where the main reinforcement interferes with the adjacent precast foundations already laid at the last laying location, and it is also possible to eliminate the need to satisfy the fixing conditions for connecting the main reinforcements to each other.

Brief Description of the Drawings

[0020] [Figure 1] It is a perspective explanatory view showing an example of joining precast foundations of an embodiment. [Figure 2] It is a plan view explanatory view showing an example of joining precast foundations of an embodiment. [Figure 3] It is an explanatory view showing an example of laying and a construction method of a precast foundation of an embodiment. [Figure 4] It is an explanatory view showing an example of laying and a construction method of a precast foundation of an embodiment. [Figure 5] It is an explanatory view showing a conventional example.

Modes for Carrying Out the Invention

[0021] Hereinafter, an embodiment according to an aspect of this invention will be described based on the accompanying drawings. As shown in FIGS. 1 and 2, the precast foundation structure of this embodiment includes at least a corner precast foundation 1 laid at a specific corner location, and corner adjacent precast foundations 2 and 3 laid adjacent to the corner precast foundation 1.

[0022] The corner-adjacent precast foundation 2 has a foundation beam section 25, a footing section 26 that extends laterally from the lower part of the foundation beam section 25, and a parapet section 27 that rises from the upper surface of the foundation beam section 25, and is a foundation with the same configuration as the general precast foundation 2A (see Figure 3) used in other locations. Four main reinforcement bars 25a are embedded in the foundation beam section 25 of the corner-adjacent precast foundation 2 in a predetermined arrangement, and these four main reinforcement bars 25a protrude from one joint surface 21 for a predetermined length in the direction of extension of the precast foundation 2. In addition, a mechanical joint is embedded on the other joint surface side of the foundation beam section 25 of the corner-adjacent precast foundation 2.

[0023] The corner-adjacent precast foundation 3 has a foundation beam section 35, a footing section 36 that extends laterally from the lower part of the foundation beam section 35, and a parapet section 37 that rises from the upper surface of the foundation beam section 35. Four main reinforcing bars 35a are embedded in the foundation beam section 35 of the corner-adjacent precast foundation 3 in a predetermined arrangement, and these four main reinforcing bars 35a protrude from one joint surface for a predetermined length in the extending direction of the precast foundation 3. In addition, two joint sections 38 are embedded on the other joint surface 31 side of the foundation beam section 35 of the corner-adjacent precast foundation 3, spaced apart from each other in the width direction of the foundation on the center side of the foundation beam section 35. Each joint section 38 has a female screw section 38a formed in the extending direction of the precast foundation 3, and the entrance of this female screw section 38a is exposed on the other joint surface 31 side. Furthermore, the joint portion 38 includes a threaded reinforcing bar 38b that is screwed into the female threaded portion 38a from the opposite side of the entrance portion. The length of the threaded reinforcing bar 38b protruding from the female threaded portion 38a is, for example, about 300 mm.

[0024] The corner precast foundation 1 comprises a foundation beam section 15, a footing section 16 extending laterally from the lower part of the foundation beam section 15, and a parapet section 17 rising from the upper surface of the foundation beam section 15. The foundation beam section 15 of the corner precast foundation 1 has a first joint surface 11 at one end and a second joint surface 12 at the other end, and also has, for example, four main beam reinforcement bars 15a in a predetermined arrangement. There are two types of corner precast foundation 1: one in which a mechanical joint 18 is embedded on the side of the first joint surface 11 (1A), and another in which four main beam reinforcement bars 15a protrude from the first joint surface 11 (1B: see Figure 3). In addition, the foundation beam section 15 has two embedded pipe sections 13 that extend from the side of the second joint surface 12 to the outer surface facing away from the second joint surface 12, and are embedded spaced apart from each other in the width direction of the foundation on the center side of the foundation beam section 15.

[0025] In this embodiment, in a plan view, the footing portion 16 has a first side 16a and a second side 16b that are perpendicular to each other, the foundation beam portion 15 is L-shaped, the first joint surface 11 is located substantially flush with the first side 16a, and the second joint surface 12 is located substantially flush with the second side 16b. Within the L-shaped foundation beam portion 15, the mechanical joint 18 is embedded in a position that does not overlap with the two buried pipe portions 13.

[0026] The first joint surface 11 of the corner precast foundation 1 is joined to the corner adjacent precast foundation 2. In this joint, the main reinforcement bars 25a of the corner adjacent precast foundation 2 are joined by the mechanical joint 18 of the corner precast foundation 1. On the other hand, the corner adjacent precast foundation 3 is joined to the second joint surface 12 of the corner precast foundation 1.

[0027] The buried pipe section 13 is made of, for example, a sheath pipe. Insertion reinforcement bars 14, made of, for example, D13 deformed reinforcing bars (e.g., high-tensile threaded steel bars), are inserted into the buried pipe section 13. A male threaded portion is formed on the tip side of the insertion reinforcement bars 14. The diameter of the buried pipe section 13 is approximately twice the nominal diameter of the insertion reinforcement bars 14.

[0028] Then, the reinforcing bar 14, which was inserted into the buried pipe section 13 from the outer surface of the corner precast foundation 1, is screwed into the female threaded portion 38a of the joint section 38 embedded on the joint surface 31 side of the corner adjacent precast foundation 3. Furthermore, grout is filled into the buried pipe section 13 to fill the gap between the buried pipe section 13 and the reinforcing bar 14. Note that the structure is not limited to screwing the male threaded portion at the tip of the reinforcing bar 14 into the female threaded portion 38a of the joint section 38, but may also be a structure in which the shaped tip of the reinforcing bar 14 is inserted into a non-threaded hole formed in the joint section 38, and grout is filled into the gap between the shaped tip and the non-threaded hole through the buried pipe section 13.

[0029] Furthermore, at least the second joint surface 12 of the corner precast foundation 1 has a cotter (recess) 12a formed in a direction perpendicular to the joint surface 12, into which grout material is filled.

[0030] With the above foundation structure, the corner precast foundation 1 is connected by inserting reinforcing bars 14 into the buried pipe section 13. As shown in Figure 3, by using the corner precast foundation 1 as the last to be laid in one enclosure foundation section, interference between the main reinforcement bars and the already laid adjacent precast foundations 2 and 3 can be avoided. Furthermore, the reinforcing bars 14 inserted into the buried pipe section 13 of the corner precast foundation 1 function not as beam main reinforcement bars 15a, but as anti-slip members that suppress displacement of the corner precast foundation 1, thus eliminating the need to satisfy anchoring conditions when connecting the main reinforcement bars.

[0031] If the inserted reinforcing bar 14 has a male threaded portion and the joint portion 38 has a female threaded portion 38a, the inserted reinforcing bar 14 can be connected to the joint portion 38 by screw fastening by screwing the male threaded portion into the female threaded portion 38a. Grout is filled into the buried pipe portion 13.

[0032] If a cotter 12a, which is a recess, is formed on the second joint surface 12 of the corner precast foundation 1, the grout hardened within the cotter 12a can receive loads in a direction perpendicular to the joint surface 12, thereby increasing the resistance to displacement of the corner precast foundation 1 relative to the corner adjacent precast foundation 3.

[0033] If the foundation beam section 15 of the corner precast foundation 1 is L-shaped, it is possible to configure the mechanical joint 18 and the buried pipe section 13 so that they do not overlap.

[0034] Furthermore, in a strip foundation where a corner precast foundation 1 is present, the main reinforcement is interrupted at the location of the corner precast foundation 1, resulting in a disconnected structure, while the continuity of the strip foundation is maintained. In light of this disconnected structure, care should be taken to ensure that the foundation contact pressure at the location of the corner precast foundation 1 is less than or equal to the bearing capacity of the ground. For example, measures such as increasing the area of ​​the footing portion 16 of the corner precast foundation 1 can be taken. Also, when a structure is designed in which vertical braces are placed between columns built on the above-mentioned strip foundation, vertical braces should not be placed at locations that straddle the disconnected section between the corner precast foundation 1 and the corner-adjacent precast foundation 3. In addition, for strip foundations with such a disconnected structure, the structural design should be carried out assuming that the inserted reinforcement 14 inserted into the buried pipe portion 13 does not bear stress.

[0035] Next, the construction method for the precast foundation structure of the embodiment will be described. The basic method in this construction method is as shown in Figure 3, starting with laying the corner adjacent precast foundation 2 which is joined to the first joint surface 11 side of the corner precast foundation 1, then laying the corner adjacent precast foundation 3 which is joined to the second joint surface 12 side of the corner precast foundation 1, and finally laying the corner precast foundation 1. In the example shown in Figure 3, the construction was carried out counterclockwise, but it is also possible to carry out the construction clockwise.

[0036] Next, another construction method for the precast foundation structure of the embodiment will be described. In this construction method, as shown in Figure 4, there are multiple corner precast foundations 1 in one enclosed foundation section (3 in this example), and the laying begins with the corner-adjacent precast foundation 2 that is joined to the first joint surface 11 side of one of the corner precast foundations 1. Here, if there is a precast foundation 2A, etc. that cannot be laid due to a manufacturing error, it is not possible to skip it and lay the next precast foundation 2A, etc. Therefore, when it is not possible to lay other precast foundations 2A, etc. that are connected to the corner-adjacent precast foundation 2, the corner-adjacent precast foundation 3A that is joined to the first joint surface 11 side of another corner precast foundation 1 is laid, and other precast foundations 2A, etc. that are connected to this corner-adjacent precast foundation 3A are laid. This prevents the foundation work from coming to a halt. In the example shown in Figure 4, the work was carried out counterclockwise, but it is also possible to carry it out clockwise.

[0037] Furthermore, other construction methods for the precast foundation structure of the embodiment will be described. In this construction method, there are multiple corner precast foundations 1 in one enclosed foundation section, and for all or part of the extended portion of these multiple corner precast foundations 1, laying begins with the corner adjacent precast foundations 2, 3 that are joined to the first joint surface 11 side or the second joint surface 12 side of the corner precast foundation 1, and after laying the corner adjacent precast foundations 3, 2 that are joined to the second joint surface 12 side or the first joint surface 11 side of the corner precast foundation 1, the corner precast foundation 1 is laid last in each extended portion.

[0038] This method makes it possible to construct all or part of the extended sections of multiple corner precast foundations 1 simultaneously.

[0039] Although embodiments of this invention have been described above with reference to the drawings, this invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as this invention, or within the equivalent scope. [Explanation of symbols]

[0040] 1: Precast foundation for corners 2: Corner adjacent precast foundation 2A: Precast foundation (general foundation) 3: Corner adjacent precast foundation 3A: Corner adjacent precast foundation 11: First joint surface 12: Second bonding surface 12a: Cotter 13: Buried pipe section 14: Insertion muscle 15:Foundation beam part 15a: Beam main reinforcement 16: Footing section 16a: First side 16b: Second side 17: Waist wall section 18: Mechanical couplings 21: Joint surface 25:Foundation beam part 25a: Main reinforcement 26: Footing section 27: Waist wall section 31: Joint surface 35: Foundation beam part 35a: Main reinforcement 36: Footing section 37: Waist wall section 38: Joint part 38a: Female screw part 38b: Threaded reinforcing bars

Claims

1. It comprises at least a precast corner foundation laid at a specific corner location, and a precast corner adjacent foundation laid adjacent to this precast corner foundation. The above-mentioned corner precast foundation has a first joint surface on one end and a second joint surface on the other end, and also has an embedded pipe section that extends from the second joint surface side to the outer surface facing away from the second joint surface. The precast foundation for the corner mentioned above and the precast foundation adjacent to the corner, which is joined to the first joint surface side, are joined by main reinforcement bars, A precast foundation structure characterized in that a joint portion is embedded on the joint surface side of the corner-adjacent precast foundation which is joined to the second joint surface side of the corner precast foundation, and that reinforcing bars inserted into the embedded pipe portion from the outer surface side of the corner precast foundation are connected to this joint portion, and that grout is filled into the embedded pipe portion.

2. A precast foundation structure according to claim 1, wherein the inserted reinforcing bar has a male threaded portion, the joint portion has a female threaded portion exposed on the joining surface side, and the male threaded portion of the inserted reinforcing bar is screwed into the female threaded portion.

3. A precast foundation structure according to claim 1, characterized in that at least the second joint surface of the corner precast foundation has a recess formed in a direction perpendicular to the joint surface in which grout material is filled.

4. A precast foundation structure according to claim 1, wherein the corner precast foundation has a foundation beam portion and a footing portion that extends laterally from the lower part of the foundation beam portion, and in a plan view, the footing portion has a first side and a second side that are perpendicular to each other, the foundation beam portion has an L-shape, the first joint surface is located substantially flush with the first side, and the second joint surface is located substantially flush with the second side.

5. A method for constructing a precast foundation structure according to any one of claims 1 to 4, characterized in that the laying is started from the corner adjacent precast foundation which is joined to the first joint surface side or the second joint surface side of the corner precast foundation, and after laying the corner adjacent precast foundation which is joined to the second joint surface side or the first joint surface side of the corner precast foundation, the corner precast foundation is laid last.

6. A method for constructing a precast foundation structure according to any one of claims 1 to 4, wherein the number of corner precast foundations is multiple in one enclosed foundation section, and the laying is started from the corner adjacent precast foundation joined to the first joint surface side or the second joint surface side of one of the multiple corner precast foundations, and if it is not possible to lay other precast foundations connected to the corner adjacent precast foundation, the laying of the corner adjacent precast foundation joined to the first joint surface side or the second joint surface side of another corner precast foundation and the laying of other precast foundations connected to this corner adjacent precast foundation is performed.

7. A method for constructing a precast foundation structure according to any one of claims 1 to 4, wherein the number of corner precast foundations is multiple in one enclosed foundation section, and for all or part of the extended portion of these multiple corner precast foundations, the laying is started from the corner adjacent precast foundation that is joined to the first joint surface side or the second joint surface side of the corner precast foundation, and after laying the corner adjacent precast foundation that is joined to the second joint surface side or the first joint surface side of the corner precast foundation, the corner precast foundation is laid last in each extended portion.

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