JP2020180492A - Precast concrete member, foundation structure, and construction method of foundation structure - Google Patents

Abstract

To provide a precast concrete member, a foundation structure, and a construction method of a foundation structure capable of making construction easy and making a construction period shorter.SOLUTION: A PC member 20 forming a part of a foundation structure 1 formed in a ground G includes: a reinforcement 21; and a precast concrete portion 22 formed so as to cover the reinforcement 21. The precast concrete portion 22 includes: an installation face 23 formed on a lower face; a joint face 25 provided to face a first side in a horizontal direction and connected with a foundation structure body 3; and a sloped face 26 formed at a second side in a horizontal direction with respect to the joint face 25, formed so as to move from the second side in a horizontal direction near the first side downward from above, and facing a diagonally lower part.SELECTED DRAWING: Figure 2

Description

The present invention relates to a precast concrete member, a foundation structure, and a method of constructing a foundation structure.

In the foundation portion that supports various structures, there is one in which footing is provided on the head of a foundation pile provided in the ground (see, for example, Patent Document 1). By footing, the load of the structure is distributed and transmitted to the ground.

In order to increase the contact area of such footing with the ground, there is a case in which a protruding portion (foundation beam) protruding in the horizontal direction from the outer peripheral portion of the footing is provided. Further, there is a case in which the horizontal protrusion dimension of the protruding portion is gradually increased from the lower side to the upper side, and an inclined surface facing diagonally downward is formed at the tip portion of the protruding portion.

JP-A-2009-35927

However, in order to form a protruding portion having an inclined surface at the tip portion as described above, the ground is excavated diagonally, level concrete is placed on the excavated surface, reinforcing bars are arranged, formwork is installed, and a mold is formed. It is necessary to place concrete in the frame. It is difficult to excavate the ground at a predetermined angle that matches the inclined surface of the protruding part, and the excavated slope may collapse due to rainfall. In addition, it is difficult and time-consuming to place level concrete on a slope excavated diagonally and level the surface. Furthermore, it is also difficult to construct the reinforcing bars and the formwork inside the excavated hole according to the inclined surface of the protruding portion.
As described above, in order to form the footing having the protruding portion, the construction difficulty is high and a great deal of labor and time are required.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a precast concrete member, a foundation structure, and a construction method of a foundation structure capable of facilitating construction and shortening the construction period. To do.

In order to achieve the above object, the present invention employs the following means.
That is, the precast concrete member according to the present invention is a precast concrete member that forms a part of a foundation structure formed in the ground, and includes a reinforcing bar, a precast concrete portion formed so as to cover the reinforcing bar, and a precast concrete portion. The precast concrete portion has an installation surface formed on the lower surface, a joint surface formed facing the first side in the horizontal direction and joined to the main body of the foundation structure, and a joint surface in the horizontal direction with respect to the joint surface. It is characterized in that it is formed on the second side, is formed so as to approach the first side from the second side in the horizontal direction from the upper side to the lower side, and has an inclined surface facing diagonally downward.

In the precast concrete member configured in this way, the joint surface of the precast concrete portion is joined to the main body of the foundation structure. The load of the superstructure supported on the foundation structure is transmitted to the ground through the installation surface and the inclined surface. By forming the foundation structure using such precast concrete members, the ground is excavated according to the inclined surface, the reinforcing bars are arranged, and the formwork is installed inside the excavation hole where the foundation structure is installed. No need. Therefore, it is possible to facilitate the construction and shorten the construction period of the foundation structure having a projecting portion that protrudes outward in the horizontal direction and has an inclined surface at the tip portion thereof.

Further, the foundation structure according to the present invention is provided in the ground and is joined to a foundation pile extending in the vertical direction and the head of the foundation pile to expand the diameter in the horizontal direction from the head of the foundation pile. The diameter portion and the outer peripheral surface of the enlarged diameter portion are provided so as to project outward in the horizontal direction, and the tip portion is formed so that the protruding dimension from the enlarged diameter portion gradually decreases from the upper side to the lower side. It is characterized by including a precast concrete projecting portion having an inclined surface facing the surface.

In the foundation structure constructed in this way, the protruding portion having an inclined surface at the tip is made of precast concrete, so that the ground is excavated according to the inclined surface inside the excavation hole where the foundation structure is installed. , There is no need to arrange reinforcing bars and install formwork. Therefore, it is possible to facilitate the construction of the foundation structure and shorten the construction period.

Further, the method of constructing the foundation structure according to the present invention includes an excavation hole forming step of excavating the ground to form an excavation hole, and a foundation pile installation step of providing a foundation pile downward from the bottom surface of the excavation hole. A PC member arranging step of arranging a plurality of precast concrete members as described above around the foundation pile in the drilling hole so that the inclined surface is separated from the foundation pile, and the PC member arranging step adjacent to each other. A formwork installation step of providing a formwork plate between the joint surfaces of the precast concrete members, and placing concrete in a space surrounded by the joint surfaces of the plurality of precast concrete members and the formwork plates. It is characterized by including a concrete placing step and a demolding step of demolding the formwork after the concrete has hardened.

In the construction method of the foundation structure configured in this way, it is possible to facilitate the construction and shorten the construction period of the foundation structure having a protruding portion having an inclined surface at the tip portion.

Further, in the method of constructing the foundation structure according to the present invention, in the PC member arranging step, the precast concrete members arranged adjacent to each other and with the inclined surfaces facing in different directions in the horizontal direction are placed on one side. A plate-shaped first plate-shaped portion fixed to the side surface of the precast concrete member, and a plate-shaped first plate-shaped portion continuously provided from the first plate-shaped portion and fixed to the side surface of the other precast concrete member. It may be connected to the two-plate-shaped portion by a connecting member having.

In the construction method of the foundation structure configured in this way, by connecting the precast concrete members adjacent to each other with the connecting member, the precast concrete member is stabilized until the concrete is cast in the concrete placing process. Can be installed. Further, this connecting member can also be used as a part of the formwork at the time of placing concrete.

Further, the method of constructing the foundation structure according to the present invention further includes a foundation slab installation step of installing a foundation slab extending in a horizontal plane on the bottom surface of the drilling hole, and in the PC member arranging step, the precast concrete member By a fixing bracket having a first fixing portion fixed along the lower end portion of the side surface and a second fixing portion continuously provided from the first fixing portion and fixed along the upper surface of the foundation plate. , The precast concrete member may be fixed.

In the construction method of the foundation structure configured in this way, the precast concrete member can be stably installed by the fixing metal fittings until the concrete is placed in the concrete placing step.

According to the construction method of the precast concrete member, the foundation structure and the foundation structure according to the present invention, it is possible to facilitate the construction and shorten the construction period.

It is a perspective view which shows the structure of the foundation structure which concerns on one Embodiment of this invention. It is sectional drawing which shows the structure of the said foundation structure. It is a perspective view which shows the precast concrete member which comprises the said foundation structure. It is a figure which shows the flow of the construction method of the said foundation structure. It is sectional drawing which shows the state which formed the excavation hole in the ground, and installed the foundation pile in the construction method of the said foundation structure. It is sectional drawing which shows the state which installed the foundation slab on the bottom surface of the excavation hole in the construction method of the said foundation structure. It is sectional drawing which shows the state which arranged the precast concrete member inside the excavation hole in the construction method of the said foundation structure. It is a perspective view which shows the structure for fixing the precast concrete member. It is sectional drawing which shows the state which arranged the formwork for forming the foundation structure main body in the construction method of the foundation structure. It is a perspective view which shows the state which arranged the formwork for forming the foundation structure main body in the construction method of the foundation structure. It is sectional drawing which shows the state which concrete was placed in the formwork and was demolded in the construction method of the said foundation structure.

The precast concrete member, the foundation structure, and the construction method of the foundation structure according to the embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing a configuration of a foundation structure according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the structure of the foundation structure.
As shown in FIGS. 1 and 2, the foundation structure 1 of the present embodiment includes a foundation pile 2, a foundation structure main body (diameter expansion portion) 3, and a plurality of protrusions 4. The foundation structure 1 is provided in the ground G (see FIG. 2). The foundation structure 1 supports superstructures (not shown) such as various buildings, bridges, and elevated structures.

As shown in FIG. 2, the foundation pile 2 is provided in the ground G and extends in the vertical direction.
The foundation structure main body 3 is joined to the head of the foundation pile 2 and has a predetermined thickness in the vertical direction. The diameter of the foundation structure main body 3 is expanded in the horizontal direction from the head of the foundation pile 2 to form a so-called footing. The foundation structure main body 3 is made of reinforced concrete and is composed of a reinforcing bar (not shown) and a concrete portion 3c placed so as to cover the reinforcing bar. In the present embodiment, the foundation structure main body 3 has a rectangular shape in a plan view.

As shown in FIG. 1, the plurality of projecting portions 4 are provided on the outer peripheral portion of the foundation structure main body 3. In the present embodiment, two protrusions 4 are provided on each side surface 3s of the foundation structure main body 3 on a rectangular plan view. The protruding portions 4 are provided at both ends in the width direction on each side surface 3s. The base end portion 4b of each protrusion 4 is joined to the foundation structure main body 3. Each projecting portion 4 is provided so as to project horizontally outward from the side surface 3s of the foundation structure main body 3 from the base end portion 4b toward the tip end portion 4s. Each protrusion 4 is formed of a precast concrete PC member (precast concrete member) 20.

FIG. 3 is a perspective view showing a precast concrete member constituting the foundation structure.
As shown in FIG. 3, the PC member 20 has a rectangular shape in a plan view. The PC member 20 has a precast concrete portion 22 and a reinforcing bar 21.
The precast concrete portion 22 has an installation surface 23, an upper surface 24, a joint surface 25, an inclined surface 26, and a pair of side surfaces 27.

The installation surface 23 is formed at the lower part of the precast concrete portion 22 so as to face vertically downward. The upper surface 24 is formed in the upper part of the precast concrete portion 22 so as to face vertically upward.

The joint surface 25 is formed at the end portion 22a on the first side in the horizontal direction of the precast concrete portion 22. The joint surface 25 is formed so as to face the first side in the horizontal direction.

The inclined surface 26 is formed in the precast concrete portion 22 at the end portion 22b on the second side in the horizontal direction opposite to the joint surface 25. The inclined surface 26 is formed so as to approach the joint surface 25 on the first side from the second side in the horizontal direction from the upper side to the lower side, and is formed so as to face diagonally downward.
The pair of side surfaces 27 are formed on both sides in the width direction orthogonal to the direction connecting the horizontal first side end portion 22a and the horizontal second side end portion 22b of the precast concrete portion 22. The pair of side surfaces 27 are formed parallel to each other.

Such a precast concrete portion 22 has an inverted trapezoidal shape when viewed from a direction orthogonal to the side surface 27.

The reinforcing bar 21 is embedded in the precast concrete portion 22. In other words, the precast concrete portion 22 is provided so as to cover the reinforcing bar 21 (in each figure, the portion of the reinforcing bar 21 embedded in the precast concrete portion 22 is not shown). A part of the reinforcing bar 21 protrudes from the joint surface 25 and the upper surface 24 of the PC member 20.

As shown in FIG. 2, in the PC member 20, the joint surface 25 faces the side surface 3s of the foundation structure main body 3, and the reinforcing bar 21A protruding from the joint surface 25 is embedded in the concrete portion 3c of the foundation structure main body 3. ing.
As a result, the PC member 20 forms a part of the protruding portion 4 of the foundation structure 1. The tip portion 4s of the protruding portion 4 is formed by the inclined surface 26 so that the protruding dimension from the foundation structure main body 3 gradually decreases from the upper side to the lower side. In the protruding portion 4 formed by the PC member 20, the installation surface 23 and the inclined surface 26 of the precast concrete portion 22 are in contact with the ground G from above.

On such a foundation structure 1, various superstructures (not shown) such as buildings, bridges, and elevated structures are provided. The reinforcing bars (not shown) protruding upward from the upper surface 3t of the foundation structure main body 3 and the reinforcing bars 21B protruding upward from the upper surface 24 of the PC member 20 are embedded in the concrete forming the upper structure. The foundation structure 1 and the superstructure are joined.

Next, the construction method of the foundation structure 1 as described above will be described.
FIG. 4 is a diagram showing a flow of a construction method of the foundation structure.
As shown in FIG. 4, the construction method of the foundation structure 1 includes a drilling hole forming process S1, a foundation pile installation process S2, a foundation slab installation process S3, a PC member placement process S4, and a mold installation process S5. It has a concrete placing step S6, a demolding step S7, and a backfilling step S8.

FIG. 5 is a cross-sectional view showing a state in which an excavation hole is formed in the ground and a foundation pile is installed in the construction method of the foundation structure.
As shown in FIG. 5, in the excavation hole forming step S1, the ground G is excavated to form the excavation hole 50. The excavation hole 50 is formed larger than the foundation structure 1 in a plan view so that the foundation structure 1 (see FIG. 2; the same applies hereinafter) can be accommodated. The inner surface 51 of the excavation hole 50 does not have to be an inclined surface.

In the foundation pile installation step S2, the foundation pile 2 is provided downward from the bottom surface 52 of the excavation hole 50. The lower end of the foundation pile 2 is provided so as to reach the support layer in the ground G. The head of the foundation pile 2 is projected upward from the bottom surface 52 of the excavation hole 50.

FIG. 6 is a cross-sectional view showing a state in which the foundation slab is installed on the bottom surface of the excavation hole in the construction method of the foundation structure.
As shown in FIG. 6, in the foundation slab installation step S3, the foundation slab 8 is installed on the bottom surface 52 of the excavation hole 50. The basic plate 8 is provided along the bottom surface 52 so as to extend in a horizontal plane, for example, in a rectangular shape in a plan view. The foundation plate 8 is made of reinforced concrete, for example, and has a predetermined thickness in the vertical direction.

FIG. 7 is a cross-sectional view showing a state in which the precast concrete member is arranged inside the excavation hole in the construction method of the foundation structure.
As shown in FIG. 7, in the PC member arranging step S4, a plurality of PC members 20 are arranged around the foundation pile 2 inside the excavation hole 50. The installation surface 23 of each PC member 20 is placed on the basic plate 8. Each PC member 20 is arranged so that the inclined surface 26 faces the side away from the foundation pile 2.

By the way, the plurality of PC members 20 to be arranged in the excavation hole 50 in the PC member arrangement step S4 are manufactured in advance and stored in a yard or the like around the excavation hole 50.
The PC member 20 can be formed by assembling a formwork according to the shape of the precast concrete portion 22, arranging reinforcing bars 21 inside the formwork, and then placing concrete in the formwork and hardening the formwork. In this case, the formwork assembly and demolding work for forming the PC member 20 can be performed not in the excavation hole 50 but on a stable ground, so that the work can be easily performed. Further, when a plurality of foundation structures 1 are installed, if the PC member 20 is sequentially manufactured on site in parallel with the work of forming the foundation structure 1 in the excavation hole 50 in the above series of steps, the construction period It can be shortened.

FIG. 8 is a perspective view showing a configuration for fixing the precast concrete member.
As shown in FIG. 8, each PC member 20 fixes the lower end portion of the side surface 27 to the base plate 8 by the fixing metal fitting 60. The fixing bracket 60 has a first fixing portion 61 and a second fixing portion 62 that are orthogonal to each other. The first fixing portion 61 is fixed by bolts or the like along the lower end portion of the side surface 27. The second fixing portion 62 extends continuously from the lower end of the first fixing portion 61 in a direction orthogonal to the first fixing portion 61. The second fixing portion 62 is fixed by bolts or the like along the upper surface of the foundation plate 8. As a result, each PC member 20 is fixed on the basic plate 8.

The PC members 20 adjacent to each other with the corner 3e (see FIG. 1) of the foundation structure main body 3 in between are close to each other on the first horizontal end 22a on which the joint surface 25 is formed, and are viewed in a plan view. They are arranged orthogonal to each other. As a result, the PC members 20 adjacent to each other are arranged so that the inclined surfaces 26 face different directions in the horizontal direction. In this way, the PC members 20 adjacent to each other are connected by the connecting member 70. The connecting member 70 has a first plate-shaped portion 71 and a second plate-shaped portion 72 that are orthogonal to each other. The first plate-shaped portion 71 has a rectangular plate shape extending in the vertical direction, and is fixed to the side surface 27 of one of the PC members 20 with bolts or the like. The second plate-shaped portion 72 extends continuously and orthogonally from the end portion of the first plate-shaped portion 71. The second plate-shaped portion 72 has a rectangular plate shape extending in the vertical direction, and is fixed to the side surface 27 of the other PC member 20 with bolts or the like. The vertical height of such a connecting member 70 is set to be substantially the same as the vertical height of the horizontal first side end portion 22a of the precast concrete portion 22.

As shown in FIG. 7, the PC members 20 arranged so as to face each other in the horizontal direction are connected by a chain 75 whose ends are fixed to the upper surface 24, and the PC members 20 are restrained from falling toward the inclined surface 26 side. To do.

FIG. 9 is a cross-sectional view showing a state in which a formwork for forming the main body of the foundation structure is arranged in the construction method of the foundation structure. FIG. 10 is a perspective view showing a state in which a formwork for forming the main body of the foundation structure is arranged in the construction method of the foundation structure.
As shown in FIGS. 9 and 10, in the formwork installation step S5, the formwork 80 for forming the foundation structure main body 3 is installed. For this purpose, a formwork plate 81 is provided between the joint surfaces 25 of the PC members 20 adjacent to each other.

In the concrete placing step S6, concrete forming the concrete portion 3c is placed in the space surrounded by the joint surface 25 of the plurality of PC members 20 and the formwork plate 81. That is, the joint surface 25 of the PC member 20 and the form plate 81 form the form 80 for forming the basic structure main body 3. Further, the connecting member 70 (see FIG. 8) that closes the space between the PC members 20 adjacent to each other also functions as a part of the mold 80.

FIG. 11 is a cross-sectional view showing a state in which concrete is cast in the formwork and removed from the mold in the construction method of the foundation structure.
As shown in FIG. 11, in the demolding step S7, the mold 80 is demolded after the concrete placed in the mold 80 is hardened to develop a predetermined strength. Specifically, the formwork plate 81 and the chain 75 are removed. The concrete portion 3c of the foundation structure main body 3 is formed by the concrete hardened in the formwork 80. As a result, the foundation structure main body 3 and the plurality of protrusions 4 (PC members 20) are joined and integrated to form the foundation structure 1.

As shown in FIG. 2, in the backfilling step S8, the gap between the inner surface of the excavation hole 50 and the foundation structure 1 is backfilled with earth and sand 100. As a result, the foundation structure 1 is installed in the ground G.
After that, an upper structure to be constructed is provided on the foundation structure 1.

In such a PC member 20 and the foundation structure 1, the joint surface 25 of the precast concrete portion 22 and the reinforcing bars 21A protruding from the joint surface 25 are joined to the foundation structure main body 3. The load of the superstructure supported on the foundation structure 1 is transmitted to the ground G via the installation surface 23 and the inclined surface 26.

In the construction method of the PC member 20, the foundation structure 1, and the foundation structure 1 configured in this way, the foundation structure 1 can be formed by using the PC member 20. This eliminates the need for excavating the ground G, arranging reinforcing bars, installing formwork, etc., in accordance with the inclined surface 26. Therefore, it is possible to facilitate the construction and shorten the construction period of the foundation structure 1 having the protruding portion 4 having the inclined surface 26 at the tip portion 4s.

Further, by connecting the PC members 20 adjacent to each other with the connecting member 70, the PC member 20 can be stably installed until the concrete is placed in the concrete placing step S6. Further, the connecting member 70 can also be used as a part of the formwork 80 at the time of placing concrete.

Further, by fixing the PC member 20 with the fixing metal fitting 60, the PC member 20 can be stably installed until the concrete is placed in the concrete placing step S6.

The assembly procedure shown in the above-described embodiment, or various shapes and combinations of the constituent members are examples, and various changes can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the arrangement of the PC members 20 has been illustrated, but the number of PC members 20 installed and the arrangement of the PC members 20 can be changed as appropriate.

1 ... Foundation structure 2 ... Foundation pile 3 ... Foundation structure body (diameter expansion part)
4 ... Protruding part 4s ... Tip part 8 ... Basic plate 20 ... PC member (precast concrete member)
21, 21A, 21B ... Reinforcing bar 22 ... Precast concrete part 23 ... Installation surface 25 ... Joint surface 26 ... Inclined surface 50 ... Drilling hole 52 ... Bottom surface 60 ... Fixing metal fittings 61 ... First fixing part 62 ... Second fixing part 70 ... Connection Member 71 ... First plate-shaped part 72 ... Second plate-shaped part 80 ... Formwork 81 ... Formwork plate G ... Ground S1 ... Drilling hole forming process S2 ... Foundation pile installation process S3 ... Foundation plate installation process S4 ... PC member placement Process S5 ... Formwork installation process S6 ... Concrete placing process S7 ... Demolding process

Claims (5)

A precast concrete member that forms part of a foundation structure formed in the ground.
Reinforcing bars and
It has a precast concrete portion formed so as to cover the reinforcing bar, and has.
The precast concrete part
The installation surface formed on the lower surface and
A joint surface that is formed facing the first side in the horizontal direction and is joined to the main body of the foundation structure,
It is characterized by having an inclined surface that is formed on the second side in the horizontal direction with respect to the joint surface, is formed so as to approach the first side from the second side in the horizontal direction from the upper side to the lower side, and faces diagonally downward. Precast concrete member. Foundation piles installed in the ground and extending in the vertical direction,
A diameter-expanded portion joined to the head of the foundation pile and expanded in the horizontal direction from the head of the foundation pile.
An inclined surface is provided so as to project horizontally outward from the outer peripheral surface of the enlarged diameter portion, and is formed at the tip portion so that the protruding dimension from the enlarged diameter portion gradually decreases from the upper side to the lower side, and the inclined surface faces diagonally downward. A foundation structure comprising a precast concrete projecting portion having a. The excavation hole formation process of excavating the ground and forming an excavation hole,
The foundation pile installation process of providing foundation piles downward from the bottom of the excavation hole,
A PC member arranging step of arranging a plurality of the precast concrete members according to claim 1 around the foundation pile inside the excavation hole so that the inclined surface is separated from the foundation pile.
A formwork installation process in which a formwork plate is provided between the joint surfaces of the precast concrete members adjacent to each other.
A concrete placing step of placing concrete in a space surrounded by the joint surface of the plurality of precast concrete members and the formwork plate.
A method for constructing a foundation structure, which comprises a demolding step of demolding the formwork after the concrete has hardened. In the PC member arranging step, the precast concrete members arranged adjacent to each other and with the inclined surfaces facing different directions in the horizontal direction are fixed to one side surface of the precast concrete member in a plate shape. Connecting with a connecting member having a first plate-shaped portion and a plate-shaped second plate-shaped portion that is continuously provided from the first plate-shaped portion and is fixed to the side surface of the other precast concrete member. 3. The method of constructing a foundation structure according to claim 3. A foundation slab installation process for installing a foundation slab extending in a horizontal plane is further provided on the bottom surface of the excavation hole.
In the PC member arranging step, a first fixing portion fixed along the lower end portion of the side surface of the precast concrete member and a first fixing portion continuously provided from the first fixing portion and fixed along the upper surface of the foundation plate. The method for constructing a foundation structure according to claim 3 or 4, wherein the precast concrete member is fixed by a fixing metal fitting having a second fixing portion.

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