JPH08209689A - Construction work method for pile - Google Patents

Abstract

PURPOSE: To optionally adjust material strength and vertical bearing force of a hollow precast concrete column body by changing the cross-sectional area without changing a pile outside diameter as well as to reduce an abandoning disposal quantity of excavating surplus soil. CONSTITUTION: An expanded bottom part 2 is formed in the lowest end part of an excavating hole 1 bored in the construction work ground, and a hollow precast concrete column body 3 is inserted into this excavating hole 1, and a tip part of the hollow precast concrete column body 3 is integrally united in the expanded bottom part 2 by cast-in-place concrete 4 placed up to reaching its upper end position. A pile periphery solidifying material 5 by mixing mud and its solidifying agent is filled in a clearance on the outer periphery of the hollow precast concrete column body 3, and plural reinforcements or a cylindrical metallic material having plural window holes on a peripheral surface are protrusively arranged on the tip of the hollow precast concrete column body 3, and these reinforcements or the cylindrical metallic material are integrally buried in the concrete 4 in the expanded part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a pile, and more particularly to a method for constructing a composite foundation pile in which a cast-in-place pile and a hollow precast concrete column are synthetically integrated.

[0002]

2. Description of the Related Art As a conventional pile construction method, concrete and cement milk are filled in the expanded bottom portion of the tip of an excavation hole provided in the ground, and a hollow precast concrete pillar is inserted into the excavation hole. There is known an NC depositing method in which the tip end portion is press-fitted and embedded in concrete in the expanded bottom portion, and the cement milk is extruded and filled in a gap around the pile to solidify the periphery of the pile to the ground.

[0003]

Generally, in order to determine the bearing capacity of a pile, it is required to compare the two methods of the yield strength (ground yield strength) obtained from the ground and the yield strength (material yield strength) obtained from the material strength of the pile. There is.

The ground yield strength increases with an increase in the outer diameter of the drilled hole bottom (effective expanded area).

Further, since the material yield strength is determined by the column size, it is generally dealt with by changing the outer diameter size. In this case, the excavation hole diameter of the column part is changed (increased),
There is a problem that it is necessary to change the dimension of the molding frame of the column body.

Further, in the above-mentioned conventional method, since the soil discharged from the excavation of the excavation hole is transported to the dump site and dumped, it is not easy to secure the dump site, and the transportation processing cost for dumping is required. In addition, since the closed hollow precast concrete column body is simply press-fitted into the concrete that has been previously filled in the expanded bottom, there is a problem that the connection integrity with the concrete is insufficient. It was

[0007]

In order to solve the above-mentioned conventional problems, the present invention forms an expanded bottom portion 2 at the lowermost end of an excavated hole 1 drilled in a construction ground, and a material is formed in the excavated hole 1. Insert the hollow precast concrete column body 3 whose strength and vertical proof strength have been adjusted to the design values by changing the cross-sectional area without changing the outer diameter dimension, and bury the required end of the hollow precast concrete pillar body 3 in the expanded bottom portion 2. Before or after the insertion of the hollow precast concrete columnar body 3, the tip of the hollow precast concrete columnar body 3 is solidified and integrated by the cast-in-place concrete 4 that is cast into the expanded bottom portion 2 until the upper end position thereof is reached. Concrete pillar 3
A method of constructing a pile in which the gap around the outer periphery of the pile is filled with a pile peripheral solidifying material 5 in which mud and its solidifying agent are mixed, and the excavation residual soil 10 of the excavation hole 1 is backfilled in the hollow portion of the hollow precast concrete columnar body 3. It is a proposal.

Further, according to the present invention, the hollow precast concrete columnar body 3 is provided with a plurality of reinforcing bars 6 or a cylindrical metal piece 9 provided with a plurality of window holes 8 on its peripheral surface, and the reinforcing bar 6 or the cylindrical metal piece 9 is projected. The present invention proposes a method of constructing a pile in which the concrete is embedded and integrated in the concrete 4 in the expanded bottom portion 2.

[0009]

The hollow precast concrete pillar 3 has its material strength and vertical yield strength adjusted to the design value by changing the cross-sectional area without changing the outer diameter dimension. It is possible to construct without changing.

The excavation residual soil 10 in the excavation hole 1 is backfilled in the hollow portion of the hollow precast concrete column body 3, and the mud soil of the excavation residual soil 10 and its solidifying agent are mixed in the gap at the outer periphery of the hollow precast concrete column body 3. Since the solidification material 5 is filled, the amount of waste disposal of excavated soil can be significantly reduced.

The hollow precast concrete column body 3 is inserted into the excavation hole 1 and then the concrete 4 placed through the hollow portion of the hollow precast concrete column body 3 is provided between the plurality of reinforcing bars 6, 6 projecting from the tip of the hollow precast concrete column body 3 or The bottom portion 2 is formed by smoothly flowing and diffusing from the window hole 8 of the tubular hardware 9 to the surroundings.
It can be surely filled inside and this rebar 6
Or to embed the tubular hardware 9 in concrete 4,
Hollow precast concrete column 3 and concrete 4
It is possible to strengthen the connection integration of the.

[0012]

[Example] As shown in FIG. 1, an excavation hole 1 having a diameter 10 cm or more larger than the outer diameter of a hollow precast concrete column is previously excavated in a construction ground by an excavation rod.
The bottom of the bottom part of the drilling rod 2
To form.

The expanded bottom portion 2 is an excavated bottom area, which is generally buried, so as to obtain a ground proof strength equal to or higher than the material strength and the vertical proof strength of the hollow precast concrete pillar 3 to be buried in the digging hole 1 later. Secure an area (effective bottom expansion area) 1.1 to 3.2 times the outer diameter of the hollow precast concrete pillar 3.

Then, as shown in FIG. 2, a hollow precast concrete pillar 3 is inserted into the excavation hole 1, and the tip end thereof is placed in the expanded bottom portion 2 from the upper end thereof to substantially the same outer diameter as the hollow precast concrete pillar 3. Hold buried to reach the depth of.

In this state, the cast-in-place concrete 4 is filled into the expanded bottom portion 2 by the tremie pipe inserted into the hollow portion of the hollow precast concrete column body 3 until the upper end position thereof is reached, and the outer circumference of the hollow precast concrete column body 3 is also filled. The pile perimeter solidifying material 5 in which mud soil (utilizing excavated soil) and its solidifying agent are mixed is filled in the gap (1) to develop the pile supporting force.

At the tip of the hollow precast concrete column body 3, a plurality of reinforcing bars 6 having a base end portion embedded in advance in the tip portion of the hollow precast concrete column body 3 are provided in a projecting manner, as shown in FIG. A tubular metal member 9 having a plurality of window holes 8 provided on the peripheral surface of a steel end plate 7 fixed to the end of a hollow precast concrete column 3 as shown in FIG. By welding and projecting, the reinforcing bars 6 or the tubular metal piece 9 can be embedded in the concrete 4 of the expanded bottom portion 2 to strengthen the connection and integration of the hollow precast concrete pillars 3.

In this way, the excavation hole is formed in the hollow portion of the hollow precast concrete pillar body 3 in which the tip portion is solidified and integrated with the concrete 4 in the expanded bottom portion 2 and the periphery is solidified and integrated with the pile surrounding solidifying material 5. The excavation surplus soil 1 of 1 is backfilled.

The material strength and vertical proof stress of the hollow precast concrete column 3 are arbitrarily adjusted by changing the cross-sectional area (wall thickness) without changing the pile outer diameter.

For example, when the outer diameter of the excavated bottom area (effective expanded area) is 1800 mm in diameter, the ground yield strength is calculated as 635 tons, while the yield strength obtained from the material strength is the column outer diameter of 10 mm.
In case of 00mm, wall thickness 130mm is 568ton, wall thickness 150mm is 64
It becomes 1 ton.

Therefore, it is possible to determine the bearing capacity of the pile by adjusting the wall thickness according to the ground bearing capacity.

[0021]

As described above, according to the present invention, the hollow precast concrete column body has its material strength and vertical yield strength adjusted to the design value by changing the cross-sectional area without changing the outer diameter dimension. It is possible to carry out the construction without changing the diameter of the drilled hole in response to changes.

Further, the excavation residual soil in the excavation hole is filled in the hollow part of the hollow precast concrete column body, and a pile circumferential solidifying material mixed with the mud soil of the excavation residual soil and its solidifying agent is mixed in the gap on the outer periphery of the hollow precast concrete column body. Since it is filled, the amount of waste disposal of excavated soil can be significantly reduced.

In addition, after inserting the hollow precast concrete pillar into the excavation hole, the concrete poured through the hollow portion is used to insert concrete into the hollow precast concrete pillar through a plurality of reinforcing bars projecting at the tip of the hollow precast concrete pillar or through a window of a cylindrical metal object. It is possible to smoothly flow and diffuse to the surroundings and to reliably fill the expanded bottom part, and since this reinforcing bar or tubular metal object is embedded in concrete, it is possible to strengthen the connection and integration of hollow precast concrete pillars and concrete. it can.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing one embodiment of a construction state according to the present invention.

FIG. 2 is a vertical sectional front view showing another embodiment of a construction state according to the present invention.

FIG. 3 is a vertical cross-sectional front view showing one embodiment of a tip portion of a hollow precast concrete columnar body according to the present invention.

FIG. 4 is a vertical sectional front view showing another embodiment of the tip portion of the hollow precast concrete pillar according to the present invention.

[Explanation of symbols]

 1 Excavation hole 2 Expanded part 3 Hollow precast concrete column 4 Concrete 5 Pile solidification material 6 Reinforcing bar 6'Ring bar 7 Steel end plate 8 Window hole 9 Cylindrical hardware 10 Unearthed soil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayasu Ishijima 2-6-2 Higashitenma, Kita-ku, Osaka City, Osaka Prefecture Marugo Foundation Co., Ltd. (72) Inventor Yutaka Shinoyama 2 Nihonbashi Kayabacho, Chuo-ku, Tokyo Chome 16-4 Marugo Co., Ltd. Tokyo Branch

Claims (3)

[Claims] 1. A design value is obtained by forming a widening bottom portion at the lowermost end of a drilled hole in the construction ground and changing the cross-sectional area of the material strength and the vertical proof stress in the drilled hole without changing the outer diameter dimension. Insert the hollow precast concrete column body adjusted to the above, bury the tip portion in the expanded bottom portion to the required depth, and strike until reaching the upper end position in the expanded bottom portion before or after inserting the hollow precast concrete column body. While solidifying and integrating the tip part of the hollow precast concrete column with the cast-in-place concrete, the pile pre-solidifying material mixed with mud and its solidifying agent is filled in the gap on the outer periphery of the hollow precast concrete column, A method for constructing a pile, characterized in that the excavated soil in an excavation hole is backfilled in the hollow portion of a precast concrete column. 2. A pile according to claim 1, wherein a plurality of rebars are provided at the tip of the hollow precast concrete column, and the rebars are embedded and integrated in cast-in-place concrete in the expanded bottom part. Construction method. 3. A hollow precast concrete pillar is provided with a cylindrical metal article having a plurality of window holes on its peripheral surface at the tip thereof, and the cylindrical metal article is embedded and integrated in cast-in-place concrete in the expanded bottom portion. The method for constructing a pile according to claim 1, which is characterized.