JP2014105535A - Construction method for cast-in-place concrete pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method for a cast-in-place concrete pile, which enables construction of the cast-in-place concrete pile with a uniform cross-section by eliminating a partial loss of area of the pile by mixing of a clod.SOLUTION: A drilling casing 1 is pressed into ground. A cylindrical net 3 is erected in the drilling casing 1. Concrete B is poured into the cylindrical net 3. The drilling casing 1 is gradually pulled out from the inside of the ground while the cylindrical net 3 and the concrete B are discharged into the ground.

Description

  The present invention relates to a method for constructing cast-in-place concrete piles, mainly due to cross-sectional defects in piles caused by collapsing of collapsed soil of hole walls or excavated soil excavated on the ground as a lump. Strength reduction can be prevented.

  As a construction method of cast-in-place concrete pile, cast-in-place concrete pile construction method in which concrete (including mortar) is placed in a pile hole drilled by an excavator such as an earth auger to create a concrete pile in the ground It has been known.

JP 2000-1849 A Japanese Patent Publication No. 5-38090

  In the construction method of cast-in-place concrete piles as described above, after drilling the pile hole, the collapsed soil of the hole wall or the excavated soil excavated on the ground becomes a lump in the unhardened concrete immediately after placement. As a result, there was a possibility that the cross-sectional defect of the pile occurred and the strength of the pile was reduced. Moreover, when drilling a pile hole, the hole wall may be uneven, and the pile cross section may not be formed into a uniform cross section.

  The present invention has been made to solve the above problems, and provides a method for constructing a cast-in-place concrete pile capable of constructing a cast-in-place concrete pile having a uniform cross section by eliminating the cross-sectional defect of the pile due to mixing of a mass of soil. It is for the purpose.

  The present invention includes a step of press-fitting a casing for drilling into the ground, a step of standing a cylindrical net in the casing for drilling, a step of placing concrete in the cylindrical net, and the cylindrical net and concrete on the ground It comprises a step of gradually pulling out the casing for hole drilling from the ground while discharging into the inside.

  According to the present invention, when concrete is placed in a pile hole formed by a casing for drilling and a cast-in-place concrete pile is created in the ground, mixing of soil blocks is prevented, thereby preventing piles due to cross-sectional defects. A strength drop can be prevented, and a cast-in-place concrete pile with a uniform cross section can be formed easily and reliably.

  In addition, a normal steel pipe can be used for the casing for drilling, and the cylindrical net can be formed from stretchable textiles, plastics, cloth, etc., but it is stretchable and impact when placing concrete. If it can endure, it is not limited to these nets.

  In particular, the present invention can prevent the collapsing soil and excavated soil of the hole wall in the concrete by the cylindrical net standing in the casing for drilling, thereby causing the contamination of the soil mass. It is possible to prevent a decrease in the strength of the pile due to the cross-sectional defect of the pile.

  Moreover, the cast-in-place concrete pile of a uniform cross section can be formed over the full length of a pile, when the cylindrical net | network which can be expanded and contracted within a pile hole expands uniformly by the concrete immediately after casting.

It is a front view which shows the casing for drilling | boring installed in the liter of a heavy construction machine. It is a perspective view which shows the casing for hole drilling, and a cylindrical net. Figures 3 (a) and 3 (b) show the construction procedure for creating cast-in-place concrete piles, Figure 3 (a) shows the process of press-fitting a casing for drilling into the ground, and Figure 3 (b) shows the process in the ground. It is a perspective view which shows the process of standing up a cylindrical net in the casing for press-fitting. 4 (a) and 4 (b) show the construction procedure for creating cast-in-place concrete piles, and Fig. 4 (a) shows how concrete is placed in a cylindrical net standing in a casing for drilling in the ground. FIG. 4 (b) is a perspective view showing the step of pulling out the casing for hole drilling from the ground. FIG. 5 (a) is a perspective view, FIG. 5 (b) is a longitudinal sectional view, and FIG. 5 (c) is a transverse sectional view of the cast-in-place concrete pile constructed by the construction method of the present invention.

  FIGS. 1-5 shows one Embodiment of the construction method of the cast-in-place concrete pile which concerns on this invention, In the figure, the code | symbol 1 is a casing for drilling for drilling a pile hole in the ground, A lower end part A bottom lid 2 is attached to the bottom.

  The bottom cover 2 is formed to have substantially the same diameter as the outer diameter of the drilling casing 1, and is attached to the lower end portion of the drilling casing 1 with an adhesive tape or the like, for example. Then, it is easily dropped by the weight of the concrete B in the drilling casing 1 and is buried with the concrete in the pile hole A when the drilling casing 1 is pulled out.

  Reference numeral 3 denotes a cylindrical net that is stood in the casing 1 for drilling. The cylindrical net is formed to have a diameter slightly smaller than the inner diameter of the casing 1 for drilling, and is stood in the casing 1 for drilling over the entire length thereof.

  The cylindrical net 3 is a stretchable geotextile that has a mesh (about 2 to 3 mm) that is permeable to concrete cement slurry and water placed in the hole-cutting casing 1 but is difficult to permeate soil and clay. It is formed in a cylindrical shape that can stand on its own from plastic or cloth.

  Reference numeral 4 denotes a construction heavy machine for press-fitting the drilling casing 1 into the ground. The leader 5 supports the drilling casing 1 vertically and moves up and down along the leader 5 to rotate the drilling casing 1. The auger motor 6 is press-fitted into the ground while being fed, and the YATCO 7 is provided to transmit the rotational force of the auger motor 6 to the drilling casing 1.

  The construction procedure for constructing the cast-in-place concrete pile of the present invention in such a configuration will be described.

 (1) First, the digging hole casing 1 is installed on the heavy construction machine 4 at the point where the cast-in-place concrete pile is to be built, and vertically laid. In this case, the casing 1 for drilling is vertically laid on the pile construction point along the leader 5 of the heavy construction machine 4. Then, the upper end portion of the hole-cutting casing 1 is connected to the auger motor 6 via a yatco 7.

 (2) Next, the pile hole A is formed by operating the auger motor 6 and press-fitting it into the ground while rotating the drilling casing 1.

  While the pile hole A is formed by the drilling casing 1, the bottom end of the drilling casing 1 is blocked by the bottom cover 2, so that no excavated soil enters the drilling casing 1. .

 (3) Next, when the pile hole A reaches a predetermined depth, the upper end portion of the casing 1 is temporarily separated from the auger motor 6. And the cylindrical net 3 is stood in the casing 1, reinforcement reinforcement (illustration omitted) is arranged as needed, and concrete B is laid.

  If the cylindrical net 3 is stood in advance in the casing 1 for drilling and is temporarily attached to the inside of the casing 1 for easy removal with an adhesive or the like, the cylindrical net 3 is cut. It can install in the ground with the casing 1 for holes, and the standing-up process of the cylindrical net 3 can be skipped.

  In addition, the reinforcing bar can be arranged efficiently by arranging bars assembled in a cage shape. Furthermore, concrete B is preferably made of concrete or mortar having high fluidity, so that the concrete can be filled well.

 (4) Next, the upper end portion of the hole-cutting casing 1 is connected to the auger motor 6 through the yatco 7 again. Then, the auger motor 6 is operated to gradually lift the casing 1 for hole drilling from the ground while rotating in the reverse direction.

  Then, the bottom lid 2 falls to the bottom of the pile hole A due to the weight of the cylindrical net 3 and the concrete B in the drilling casing 1, and at the same time, the cylindrical net 3 and the concrete B are removed from the lower end of the drilling casing 1. A foundation pile made of cast-in-place concrete is formed in the pile hole A by being discharged into the pile hole A and filled in the pile hole A.

  In this case, in particular, since the cylindrical net 3 is formed of a stretchable geotextile or the like, the concrete B immediately after placement is uniformly expanded in the pile hole A by its own weight, so that a uniform cross-section is cast. Concrete piles can be formed.

  Further, when the drilling casing 1 is pulled out, the concrete B can be uniformly and densely filled into the pile hole A by applying vibration to the concrete B through the drilling casing 1. Furthermore, in the step of pulling out the casing 1 for hole drilling, the concrete B may be additionally placed in the casing 1 for hole drilling if necessary.

  With the above construction procedure, a cast-in-place concrete pile having a uniform cross section can be reliably and easily formed in the ground.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to prevent a decrease in strength due to a cross-sectional defect of a pile caused by a fallen soil of a hole wall or mixing of a mass of excavated soil excavated on the ground.

1 Casing for Drilling 2 Bottom Cover 3 Cylindrical Net 4 Construction Heavy Equipment 5 Leader 6 Auger Motor 7 Yatco

Claims (2)

  A process of press-fitting a casing for drilling into the ground, a process of installing a cylindrical net in the casing for drilling, a process of placing concrete in the cylindrical net, and discharging the cylindrical net and concrete into the ground A cast-in-place concrete pile construction method comprising a step of gradually pulling out a casing for drilling from the ground.   2. The cast-in-place concrete pile construction method according to claim 1, wherein the cylindrical net is formed from a stretchable geotextile, plastic, or cloth.

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