JP6909607B2 - How to build cast-in-place piles and foundations - Google Patents

Description

The present invention relates to a cast-in-place pile provided with an extra concrete portion in which an insulating auxiliary tool for forming a cross-sectional defect is embedded, and a method for constructing a foundation having the cast-in-place pile.

Conventionally, cast-in-place piles are constructed by the following procedure. First, a hole is drilled in the ground to form a pile hole, and a pile main bar is inserted into the pile hole to pour concrete to a predetermined height. As a result, a pile body in which the pile main bar is driven is constructed, and an extra concrete portion in which the pile main bar extending upward from the pile body is embedded is formed. Next, the soil generated at the site is backfilled in the pile holes, and then the ground is excavated to expose the surplus concrete part. Since the concrete in this surplus concrete part is poorly mixed, the concrete in this surplus concrete part is lifted out and removed (pile head treatment).

Here, the following method has been proposed as a method for easily performing pile head processing.
Patent Document 1 describes a method in which a vinyl pipe is attached as a curing material to the upper part of the core reinforcing bar to be lifted, and a columnar precast concrete body prepared in advance is arranged in the space where the core reinforcing bar is arranged. It is shown. With this precast concrete body, the amount of concrete in the surplus concrete portion can be reduced, and the core reinforcing bar can be protected when the concrete in the surplus concrete portion is ejected.

Patent Document 2 proposes a pile head processing cap that covers a pile main bar of a cast-in-place pile. This pile head processing cap has a lower double pipe having a bottom plate in which a through hole and a plurality of slits are formed in order to penetrate the pile main bar of the reinforcing bar cage at the peripheral edge, and a ceiling in which a plurality of air vent holes are formed. It consists of an upper double pipe with a plate. By covering the pile main bar with the lower double pipe and the upper double pipe fitted, the amount of concrete in the surplus part can be reduced, and when the concrete in the surplus part is pulled out, the pile reinforcing bar is used. Can be protected.

In the pile head treatment of cast-in-place piles, after the cast-in-place piles are constructed, the soil generated at the site is backfilled in the pile holes, and then the ground is excavated with a heavy excavation machine to expose the surplus part of the piles. At this time, the bucket of the heavy excavation machine may come into contact with the pile reinforcing bar protruding from the surplus portion, and the pile reinforcing bar may be damaged. Further, the methods of Patent Documents 1 and 2 can protect the pile reinforcing bars in the surplus portion, but cannot protect the pile reinforcing bars extending above the surplus portion.

Japanese Unexamined Patent Publication No. 2005-213963 Japanese Unexamined Patent Publication No. 2006-299535

The present invention provides a method for constructing a cast-in-place pile and a foundation having a cast-in-place pile that can prevent damage to the pile reinforcement by the heavy excavation machine when excavating the ground with a heavy excavation machine after constructing the cast-in-place pile. Is an issue.

The present inventors lock the pile main reinforcement at the lower end of the excess concrete portion in contact with the pile body as a cast-in-place pile that can remove the excess concrete at the pile head with good workability without damaging the pile reinforcement. Insulation aids are installed to provide cross-section defects in the pile body, and the pile head backfilling part that covers the pile main reinforcement extending upward from the surplus concrete part is formed of recycled gravel or recycled sand. It can be easily taken out from the head backfilling part without damaging the main reinforcement of the pile, and by burying the insulation auxiliary tool in the surplus concrete part, the dismantling and removal work of the surplus concrete part can be carried out efficiently. Focusing on the points, we have invented the cast-in-place pile of the present invention and the method for constructing the pile.

The cast-in-place pile (for example, cast-in-place pile 1 described later) of the first invention includes a concrete pile body (for example, a pile body 10 described later) and a pile main bar (for example, described later) driven into the pile body. A cast-in-place pile having a pile main bar 21), and a pile head backfilling portion (for example, described later) in which a pile main bar extending upward from the pile body is embedded in the upper surface of the pile body of the cast-in-place pile. A pile head backfilling portion 30) is provided, and the pile head backfilling portion is characterized in that it is formed of recycled gravel and / or recycled sand.

According to the present invention, the pile head backfilling portion in which the pile main reinforcement is buried is formed of recycled gravel or recycled sand, so that the soil quality of the pile head backfilling portion is clearly different in color and hardness from the surrounding soil. This is different, and when removing the pile head backfill portion, it is possible to prevent the pile main bar buried in the pile head backfill portion from being damaged due to excessive excavation with a heavy machine. The recycled gravel and recycled sand referred to here are those obtained by crushing and classifying concrete debris generated during demolition work of a building to remove foreign substances such as reinforcing bars. By backfilling the pile head backfill with recycled gravel and / or recycled sand created from concrete rubble, it is not necessary to bring in backfill soil, and construction costs can be reduced.

In the cast-in-place pile of the second invention, the pile body is a pile body used as a pile (for example, a pile body 11 described later) and an extra concrete portion formed on the pile body (for example, described later). The surplus concrete portion 12) is provided, and the lower end portion of the surplus concrete portion in contact with the pile body is supported by the pile main bar to insulate the concrete of the pile body and the surplus concrete portion. It is characterized in that an insulating auxiliary tool (for example, a spacer 13 described later) is provided.
The lower end portion of the surplus concrete portion referred to here includes a lower end surface of the surplus concrete portion and a position above a predetermined height from the lower end surface of the surplus concrete portion.

According to the present invention, by installing a concrete insulating auxiliary tool supported by the pile main bar substantially horizontally on the boundary surface between the pile body and the surplus concrete portion, the insulating auxiliary tool is used as a cross-sectional defect portion of the pile body. Therefore, the cross-sectional area of the surplus concrete portion is smaller than the cross-sectional area of the pile body. Therefore, when the surplus concrete portion is pulled out and removed, the surplus concrete portion can be easily separated from the pile body.

The method of constructing the foundation of the third invention is a method of constructing a foundation having cast-in-place piles (for example, foundation 6 described later), in which holes are drilled in the ground (for example, ground 3 described later) and pile holes (for example, the foundation 6 described later). , The pile hole 4) described later is formed, the pile main bar is inserted into the pile hole, and concrete is poured to a predetermined height to construct the pile main body into which the pile main bar is driven, and from the pile main body. A step of forming an extra concrete portion in which an upwardly extending pile main bar is embedded (for example, step S1 described later) and a circumference of the pile main bar extending upward from the extra concrete portion of the pile hole are formed with recycled gravel and / Or a step of backfilling with recycled sand to form a pile head backfill portion (for example, step S2 described later), and recycled gravel and / or recycled sand forming the pile head backfill portion by excavating the ground. (For example, step S3 described later), a step of pulling out the concrete of the surplus concrete portion and removing it (for example, step S4 described later), and placing new concrete on the pile body. Then, a step of constructing a foundation (for example, step S5 described later) is provided.

According to the present invention, since the pile head backfilling portion covering the pile main bar is formed of recycled gravel or recycled sand, the soil quality of this pile head backfilling portion is clearly different in color and hardness from the surrounding soil. Therefore, when the pile head backfill portion is removed, the pile main bar can be exposed without damaging the pile main bar embedded in the pile head backfill portion. Therefore, since the pile main bar extends upward from the upper surface of the pile body without being damaged, the foundation and the pile are integrated by fixing the pile main bar to the foundation.

The cast-in-place pile of the fourth invention (for example, cast-in-place pile 1A described later) is a cast-in-place pile having a concrete pile body and a pile main bar driven into the pile body, and is the pile body. Is provided with a pile main body used as a pile and an extra concrete portion formed on the pile main body, and a pile main bar extending upward from the pile main body is housed in the extra concrete portion. The lower end of the surplus concrete portion is provided with an insulating auxiliary tool that is supported by the pile main bar and insulates the concrete of the pile body from the surplus concrete portion.

According to the present invention, since the pile main bar extending upward from the pile body is contained in the surplus concrete portion, even if the surrounding ground is excavated by the excavation heavy machine after the cast-in-place pile is constructed, the pile by the excavation heavy machine is used. Damage to the reinforcing bars can be prevented.
In addition, by installing a concrete insulation auxiliary tool supported by the pile main bar substantially horizontally on the boundary surface between the pile body and the extra concrete part, this insulation auxiliary tool becomes a cross-sectional defect part of the pile body and the extra pile. The cross-sectional area of the concrete part is smaller than the cross-sectional area of the pile body. Therefore, when the surplus concrete portion is pulled out and removed, the surplus concrete portion can be easily separated from the pile body.

According to the present invention, when excavating the ground with a heavy excavation machine after constructing a cast-in-place pile, it is possible to prevent damage to the pile reinforcing bar by the heavy excavation machine. In addition, the surplus concrete portion can be lifted out quickly and at low cost.

It is sectional drawing of the cast-in-place pile which concerns on 1st Embodiment of this invention. It is an enlarged view (the upper part of a pile body) of the part surrounded by the broken line A of FIG. FIG. 2 is a cross-sectional view taken along the line BB of FIG. 2 (lower end surface of the surplus concrete portion in contact with the pile body). It is explanatory drawing of the method of attaching the insulation auxiliary tool to the pile main bar of the cast-in-place pile. It is a flowchart of the construction procedure of the foundation having the cast-in-place pile. It is explanatory drawing of the said foundation construction procedure (the construction situation of the pile body, the pile concrete part, and the pile head backfill part). It is explanatory drawing of the said foundation construction procedure (the second, the situation where the foundation was constructed on the pile body). It is an enlarged view of the pile head part of the cast-in-place pile which concerns on 2nd Embodiment of this invention.

In the first embodiment of the present invention, an extra concrete portion in which an insulating auxiliary tool forming a cross-sectional defect is embedded in the upper surface of the pile body, and a pile in which the pile main bar is covered with recycled gravel or recycled sand above the surplus concrete portion. It is a method of constructing a cast-in-place pile provided with a head backfill portion and a foundation having the cast-in-place pile. In the second embodiment of the present invention, the pile main bar extending upward from the pile body is housed in the extra concrete portion formed on the upper surface of the pile body without providing the pile head backfilling portion, and the extra concrete. It is a cast-in-place pile that does not protrude above the part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the following embodiments, the same components will be designated by the same reference numerals, and the description thereof will be omitted or simplified.
[First Embodiment]
FIG. 1 is a vertical cross-sectional view of a cast-in-place pile 1 according to the first embodiment of the present invention.
The cast-in-place pile 1 is constructed by excavating the ground 3 from the ground surface 2 to form a pile hole 4 and inside the pile hole 4. The cast-in-place pile 1 has a concrete pile body 10 and a pile reinforcing bar 20 driven into the pile body 10.

FIG. 2 is an enlarged view of the portion surrounded by the broken line A in FIG. FIG. 3 is a cross-sectional view taken along the line BB of FIG.
The pile reinforcing bar 20 includes a plurality of pile main bars 21 arranged in an annular shape and extending in the vertical direction, and a pile band bar 22 wound around the pile main bar 21.
On the upper surface of the pile body 10 of the cast-in-place pile 1, a pile head backfilling portion 30 in which a pile main bar 21 extending upward from the pile body 10 is embedded is provided. The pile head backfilling portion 30 is formed by backfilling recycled gravel and recycled sand in the pile hole 4 from the pile body 10 to the ground surface 2.

The pile body 10 includes a pile main body 11 used as a pile, and an extra concrete portion 12 formed on the pile main body 11 and later removed.
The pile main bar 21 extends upward from the pile main body 11 and penetrates the extra concrete portion 12, and protrudes upward from the extra concrete portion 12. Therefore, the tip of the pile main bar 21 is buried in the reclaimed gravel and reclaimed sand of the pile head backfilling portion 30.

At the lower end of the surplus concrete portion 12 in contact with the pile body 11, a spacer 13 is provided as an insulating auxiliary tool that is supported by each pile main bar 21 and insulates the concrete of the pile body 11 and the surplus concrete portion 12. There is.
As shown in FIG. 4, the spacer 13 has a resin disk shape in which a slit 14 is formed, and is supported by the pile main bar 21 by fitting each pile main bar 21 into the slit 14. As a result, in the surplus concrete portion 12, the spacer 13 forms the first cross-sectional defect portion 16 in the substantially horizontal direction.

In the present embodiment, the spacers 13 are attached to all the pile main bars 21, but the present invention is not limited to this, and the spacers may be attached only to the pile main bars selected as appropriate. For example, spacers may be attached to every other pile main bar or every two piles. Further, when the pile reinforcing bar 20 is grounded on the ground surface, the spacer 13 may be fixed to the pile main reinforcing bar 21 with a binding wire.

Further, in the portion of the pile main bar 21 above the pile body 11, a tubular cover 15 is provided in order to provide a non-adhesive region between the concrete, recycled gravel, and recycled sand and the reinforcing bar which is the pile main bar. It is covered from above. The cover 15 has a tubular shape with the upper end closed and the lower end open, and the lower end of the cover 15 is placed on the spacer 13.

By arranging the tubular cover 15 in contact with the upper surface of the spacer 13, the buoyancy acting on the spacer 13 can be suppressed by the cover 15, and the spacer 13 closes the opening on the lower end side of the cover 15 to cover the cover. It is possible to prevent concrete from entering the inside of 15.
Further, since the upper end of the tubular cover is closed, the upper end of the cover 15 is caught by the upper end of the pile main bar 21, so that the lower end of the cover 15 can be arranged on the upper surface of the spacer 13.

Further, in the surplus concrete portion 12, a second cross-sectional defect portion 17 extending in the vertical direction is formed by the tubular cover 15 covering the pile main bar 21. From the above, since the spacer 13 and the cover 15 are continuously arranged in the surplus concrete portion 12, the first cross-section defect portion 16 and the second cross-section defect portion 17 are integrally formed.

The procedure for constructing the foundation 6 having the above cast-in-place pile 1 will be described with reference to the flowchart of FIG.
In step S1, as shown in FIG. 6A, the cast-in-place pile 1 is constructed.
That is, a reinforcing bar basket in which the pile reinforcing bars 20 are integrated is prepared on the ground surface 2, a cover 15 is put on the tip of the pile main reinforcing bars 21, and a spacer 13 is attached. Next, a hole is drilled from the ground surface 2 to the ground 3 to form a pile hole 4, a reinforcing bar cage of the pile reinforcing bar 20 is inserted into the pile hole 4, and concrete is poured to a predetermined height. As a result, the pile main body 11 into which the pile main bar 21 is driven is constructed, and the extra concrete portion 12 in which the pile main bar 21 extending upward from the pile main body 11 is embedded is formed.

In step S2, as shown in FIG. 6B, the pile hole 4 is backfilled with recycled gravel and recycled sand to form a pile head backfill portion 30. As a result, the pile main bar 21 extending upward from the surplus concrete portion 12 is backfilled with recycled gravel and recycled sand.

In step S3, as shown in FIG. 7A, the ground 3 is excavated to the floor surface 5, the recycled gravel and the recycled sand forming the pile head backfill portion 30 are removed, and the remainder of the cast-in-place pile 1 is removed. The piled concrete portion 12 is exposed.

In step S4, as shown in FIG. 7B, the concrete of the surplus concrete portion 12 is pulled out and removed, and the spacer 13 and the cover 15 are removed.
In step S5, as shown in FIG. 7B, concrete is newly cast on the pile main body 11 to construct the foundation 6.

According to this embodiment, there are the following effects.
(1) Since the pile head backfilling portion 30 in which the pile main bar 21 is buried is formed of recycled gravel and recycled sand, the soil quality of the pile head backfilling portion 30 is clearly different in color and hardness from the surrounding soil. Therefore, when the pile head backfilling portion 30 is removed, it is possible to prevent the pile main bar 21 buried in the pile head backfilling portion 30 from being damaged due to excessive excavation with a heavy machine.

(2) By installing the spacer 13 supported by the pile main bar 21 substantially horizontally on the boundary surface between the pile body 11 and the surplus concrete portion 12, the spacer 13 becomes a cross-sectional defect portion of the pile body 10 and becomes a surplus. The cross-sectional area of the concrete portion 12 is smaller than the cross-sectional area of the pile body 11. Therefore, when the surplus concrete portion 12 is pulled out and removed, the surplus concrete portion 12 can be easily separated from the pile body 10.

(3) In the surplus concrete portion 12, the first cross-section defect portion 16 by installing the concrete spacer 13 substantially horizontally and the second cross-section defect portion 17 extending in the vertical direction along the pile main bar 21 , Are formed as one. In this way, since the surplus concrete portion 12 is provided with the cross-sectional defect portions 16 and 17 in the vertical direction and the horizontal direction, the pile main body 11 and the surplus concrete portion 12 can be easily separated, and the surplus concrete portion 12 can be easily separated. Easy to disassemble.

[Second Embodiment]
FIG. 8 is an enlarged view of a pile head portion of the cast-in-place pile 1A according to the second embodiment of the present invention.
In the first embodiment, the pile head backfilling portion of the first embodiment is not provided, and the upper end portion of the pile main bar 21 extending upward from the pile body 11 is contained in the surplus concrete portion 12. Different from the embodiment.

That is, in the present embodiment, the pile main bar 21 extending upward from the pile main body 11 is housed in the surplus concrete portion 12, and does not project upward from the surplus concrete portion 12. Further, the portion of the pile main bar 21 above the pile body 11 is covered with a tubular cover 15.
Further, the pile head backfilling portion of the first embodiment is not provided, and the depth of the pile hole 4 is shallow.
Further, as in the first embodiment, a spacer 13 as an insulating auxiliary tool supported by the pile main bar is provided at the lower end of the surplus concrete portion 12 in contact with the pile main body 11.

According to this embodiment, in addition to the above-mentioned (2) and (3), the following effects are obtained.
(4) Since the pile main bar 21 extending upward from the pile body 11 is housed in the surplus concrete portion 12, even if the surrounding ground is excavated with the excavation heavy machine after the cast-in-place pile 1A is constructed, this excavation heavy machine Can prevent damage to the pile main bar 21 due to
(5) In the cast-in-place pile 1A, since the pile head backfilling portion is not provided on the upper surface of the pile body 10, it is not necessary to backfill or excavate the pile head backfilling portion, and the pile hole 4 for constructing the cast-in-place pile 1A Can be shallow. Therefore, the construction period of the building can be shortened and the construction cost can be reduced.

The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.
In the above-described first embodiment, the spacer 13 as an insulating auxiliary tool is provided at the lower end portion of the surplus concrete portion 12, but the present invention is not limited to this, and the spacer may not be provided. By doing so, it is possible to prevent damage to the pile main bar 21 and to carry out the lifting work of the surplus concrete portion 12 quickly and at low cost, although it is not sufficient.

Further, in each of the above-described embodiments, the spacer 13 as the insulating auxiliary tool has a disk shape, but the spacer is not limited to this, and the spacer may have a star shape, a heart shape, or a rectangular shape provided with slits. ..
Further, in each of the above-described embodiments, the spacer 13 is arranged only at the lower end portion of the surplus concrete portion 12, but the present invention is not limited to this. For example, when the cast-in-place pile 1 has a large diameter, or when the height of the surplus concrete portion is high and the amount of concrete to be removed is large, not only the lower end portion of the surplus concrete portion but also the surplus concrete portion It is preferable to increase the cross-sectional defects of concrete by providing a multi-stage spacer also in the middle portion and the upper end portion of the concrete.

1, 1A ... Cast-in-place pile 2 ... Ground surface 3 ... Ground 4 ... Pile hole 5 ... Floor surface 6 ... Foundation 10 ... Pile body 11 ... Pile body 12 ... Extra concrete part 13 ... Spacer (insulation auxiliary tool) 14 ... Slit 15 ... Cover 16 ... First cross-sectional defect 17 ... Second cross-section defect 20 ... Pile reinforcement 21 ... Pile main reinforcement 22 ... Pile band reinforcement 30 ... Pile head backfill

Claims (3)

A cast-in-place pile having a concrete pile body and a pile main bar driven into the pile body.
On the upper surface of the pile body of the cast-in-place pile, a pile head backfilling portion in which a pile main bar extending upward from the pile body is embedded is provided.
The pile head backfill is made of recycled gravel and / or recycled sand .
The pile body includes a pile body used as a pile and an extra concrete portion formed on the pile body.
At the lower end of the surplus concrete portion in contact with the pile body, a slit of a disk-shaped spacer is fitted and attached to the pile main bar.
A cast-in-place pile characterized in that the concrete of the pile body and the surplus concrete portion are insulated by the spacer. A method of constructing a foundation with cast-in-place piles
Prepare a reinforcing bar cage including the pile main bar, insert the slit of the disk-shaped spacer into the pile main bar, and attach it.
By drilling holes in the ground to form pile holes, inserting the reinforcing bar cage into the pile holes, and placing concrete to a predetermined height, a pile body in which the pile main bars are driven is constructed, and the pile is constructed. A step of forming an extra concrete portion in which a pile main bar extending upward from the main body is embedded and arranging the spacer at the lower end portion of the extra concrete portion in contact with the pile main body .
A step of backfilling around the pile main bar extending upward from the surplus concrete portion of the pile hole with recycled gravel and / or recycled sand to form a pile head backfill portion.
A step of excavating the ground to remove recycled gravel and / or recycled sand forming the pile head backfill portion, and
The process of pulling out and removing the concrete from the surplus concrete part,
A method for constructing a foundation, which comprises a step of newly placing concrete on the pile body to construct the foundation. A cast-in-place pile having a concrete pile body and a pile main bar driven into the pile body.
The pile body includes a pile body used as a pile and an extra concrete portion formed on the pile body.
The pile main bar extending upward from the pile body is housed in the surplus concrete portion.
At the lower end of the surplus concrete portion, a slit of a disk-shaped spacer is fitted and attached to the pile main bar.
A cast-in-place pile characterized in that the concrete of the pile body and the surplus concrete portion are insulated by the spacer.

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