JPH0280710A - Preparing cast-in-place concrete pile - Google Patents

Abstract

PURPOSE:To contrive improvement of bearing capacity by a method wherein a reinforcing bar basket is inserted and filled with gravels or the like after excavated soil is discharged from the inside of the casing and the diameter of the casing bottom is expanded by tamping gravels or the like, and after removal of the casing, cement-mortar is grouted therein. CONSTITUTION:With a casing 1 and rotating auger screw, digging is made toward the inside of the earth and excavated soil is discharged. Then, with up-and-down movement of a drop hammer, gravels in an appropriate quantity are thrown in to the casing. Then tamping is made at the bottom of the bore and the bottom end of the casing 1 is radially expanded. After inserting a reinforcing bar basket 6 and a pipe 11 having through holes 10, the casing is filled with gravels or the like that are thrown in from above. After the casing 1 is removed, cement-mortar is grouted through the pipe 11 and a bulbous part 13 is formed thereby at the bottom of a pile. Then bearing capacity of the pile can be increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a construction method for cast-in-place concrete piles.

[Conventional technology]

The conventional construction method for cast-in-place concrete piles was established in 1977.
- While driving a parent earth auger having screw type blades on the outer periphery of a steel pipe as in Publication No. 20707, and a child earth auger having screw type blades provided on the outer periphery of the tube shaft and inserted into the parent earth auger, respectively. After excavating from the ground to a predetermined depth, the drives of the parent earth auger and child earth auger are stopped and only the child earth auger is pulled up.

At this time, the soil in the parent earth auger is caught in the blades of the child earth auger and discharged.

When the father earth auger is pulled up, solidified material such as fresh concrete is press-filled from the tip using the through hole in the tube shaft of the child earth auger.

Therefore, before the refractory material hardens, a reinforcing bar cage is inserted into the parent earth auger and buried in the consolidated material.

Then, remove the parent earth auger while rotating it in the opposite direction.

[Problem to be solved by the invention] Mixer trucks drive into the ready-mixed concrete production site, receive the ready-mixed concrete, and transport the ready-mixed concrete to the site for pouring, which requires a large number of mixer trucks and causes traffic stagnation. There were problems that caused the occurrence of problems and increased costs.

When the earth auger is pulled up and the excavated soil is discharged, soil always remains at the bottom of the drilled hole, resulting in a problem of reduced bearing capacity.

[Means to solve the problem]

In order to solve the above problems, this invention installs a casing underground, drains the soil inside the casing to make the inside of the casing hollow, and then fills the hollow bottom with the required amount of gravel or crushed stone. Then, the gravel or crushed stone is compacted to form a bulbous shape while expanding the diameter of the lower end of the casing, then a reinforcing bar cage is first inserted into the casing, and then gravel or crushed stone is filled, and After the casing was removed, cement paste or cement mortar was press-fitted into the drilled hole to create cast-in-place concrete piles.

〔Example〕

Next, the construction method for cast-in-place concrete piles will be explained based on the attached drawings.

First, as shown in Fig. 1, the casing 1 and the auger screw 2 inserted into the casing 1 are erected on the pile core, and after confirming the verticality using a transit or the like,
The casing 1 and the auger screw 2 are rotated to excavate from the ground to the ground.

The casing 1 and the auger screw 2 are connected at their respective ends to a drive machine with a speed reducer (not shown) that moves up and down along the guide of the leader mast, and excavates while rotating in opposite directions.

After the tips of the casing 1 and the auger screw 2 reach the support layer as shown in FIG. 2, their respective rotations are stopped and the connection between the casing 1 and the driving machine is released.

Then, as shown in FIG. 3, the auger screw 2 is pulled up.

At this time, as shown in Fig. 4, the casing 1 remains underground, and the soil inside the casing 1 is removed by the auger screw 2.
It is caught in the feathers and expelled.

Thereafter, as shown in FIG. 5, the drop hammer 3 inserted into the casing 1 is raised and lowered to compact the bottom of the drilled hole.

In addition, when a small amount of earth and sand remains at the bottom of the drilled hole when compacting using the drop hammer 3, a bucket may be used to collect it.

Further, when tamping, an appropriate amount of gravel or crushed stone 5 is placed at the bottom of the drilled hole using a packet 4 as shown in FIG.

After the above tamping, the casing 1 is
Insert reinforcing bar tIt6 inside.

The reinforcing bars 116 mentioned above are lifted by the wires 7 and inserted. Insertion is mostly carried out under its own weight.

As shown in FIG. 7, after filling the casing 1 with gravel or crushed stones 8, the casing 1 is removed and cement paste and Press in cement mortar.

The method for removing the casing 1 above is to attach the casing 1 to the drive machine.
and then pull up the casing 1 while rotating it.

Also, the method of press-fitting cement paste and cement mortar is as follows:
In the illustrated case, a pipe 11 having a plurality of through holes 10 at the bottom is inserted on the center line of the reinforcing bar cage 6 before the crushed stone 8 is introduced,
Although the above-mentioned pipe 11 is used for press-fitting, other methods may be used for press-fitting.

As shown in FIG. 9, a bulbous portion 13 is formed at the lower end (pile tip) of the cast-in-place concrete pile 12 created underground by press-fitting the cement paste or cement mortar.

The above-mentioned bulb part 13 is compacted by tamping the gravel and crushed stones 5 supplied to the bottom of the drilling hole, which presses the gravel and crushed stones against the entire surface of the peripheral wall at the bottom of the drilling hole and expands the diameter of the peripheral wall. Gravel and crushed stone become bulbous.

In addition, other than the auger screw, a method of excavating while rotating the packet and then removing the soil may be adopted.

In addition to the drop hammer, for example, a vibrator or the like may be used to compact the gravel or crushed stone.

〔effect〕

As described above, according to the method for constructing cast-in-place concrete piles according to the present invention, since fresh concrete is not filled, a mixer truck becomes unnecessary and traffic stagnation caused by the mixer truck can be eliminated.

In addition, since the gravel or crushed stone supplied to the bottom of the drilled hole in the casing is compacted, the circumference of the bottom of the drilled hole escapes in the circumferential direction and expands in diameter as the tamping occurs. For this reason, the tip of the concrete pile becomes bulbous and can provide a large bearing capacity.

Furthermore, since the excavated soil is not industrial waste unlike the earth auger construction method or the reverse circulation construction method, it is easy to transport and it is possible to significantly reduce costs.

[Brief explanation of the drawing]

The drawings show the construction method according to the present invention, and FIGS. 1 and 2 are longitudinal sectional front views showing excavation using a casing and an auger screw, and FIG. 3 is a partially cutaway front view showing soil discharge. Figure 4 is a vertical front view of gravel and crushed stone poured into the bottom of the casing, Figure 5 is a vertical front view of tamping using a drop hammer, Figure 6 is a vertical front view of reinforcing rods and pipes inserted, Figure 7 is a vertical front view with gravel and crushed stone added to the same as above, Figure 8 is a vertical front view with the casing removed, and Figure 9 is a vertical front view with concrete piles constructed. 1...Casing, 2...Auger screw 3...River/drop hammer 5...Gravel and crushed stone, 6...Reinforced steel dragon, 8... ... Gravel and crushed stone, 11 ... Glass pipe, 12 ... Concrete pile, 13 ... Bulb part. Patent applicant: Satoshi Enoki, Hiroshi Enoki, Hiroshi Enoki, Agent Fumiji Kamata

Claims (1)

[Claims] (1) After installing a casing underground and draining the soil inside the casing to make the inside of the casing hollow,
The required amount of gravel or crushed stone is supplied to the hollow bottom, and then the gravel or crushed stone is compacted to form a bulbous shape while expanding the diameter of the lower end of the casing, and then a reinforcing bar cage is first inserted into the casing. A method for constructing cast-in-place concrete piles, which is characterized by filling the hole with gravel or crushed stone, removing the casing, and then press-fitting cement paste or cement mortar into the hole.