JPS6325130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for creating pile holes used in foundation work for construction.

Earth augers are often used to drill holes when erecting prefabricated piles or constructing on-site piles. As is well known, an earth auger is a device in which a rotary drive mechanism and a screw connected to this are suspended vertically from a boom installed on a movable vehicle, and the screw is rotated to drill into the ground. In the conventional earth auger, the auger head 1 at the tip of the screw has two blades 2 and 3 as shown in FIG. Of these two blades 2 and 3, blade 2 is continuous with the blade of the upper screw (not shown), blade 3 is provided symmetrically with respect to blade 2, and both have a digging blade 4 at the tip. Multiple plants are planted. The reason why such a plurality of blades 2 and 3 are provided is to maintain balance during excavation, but with such a structure, the pitch gap between the blades is narrow, so it is easy for boulders etc. to bite and cause a compaction effect. Further, since the second blade 3 is not continuous with the blade of the upper screw main body, the earth and sand pushed up by the blade 3 remains at the discontinuous part of the blade, causing a compaction effect. If the earth and sand are compacted in this way, the screw action cannot be exerted as a matter of course, causing problems in excavation.

The purpose of the present invention is to eliminate the disadvantages of the conventional example,
To provide a method for constructing a pile hole that can be excavated without clogging with earth and sand and without bending even when using an earth auger.

However, according to the present invention, the auger head is equipped with only one screw blade, and a cutting blade is installed in the notch at the tip of the blade in the direction of rotation of the blade. By introducing the earth auger connected to the tip of the auger screw body into the excavation casing that has a digging blade at the tip, and cutting into the ground with the casing leading while rotating the earth auger and casing in opposite directions. achieved.

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, to explain the auger head used in the construction method of the present invention, the auger head 1a is obtained by removing the blade 3 from the auger head 1, as shown in Fig. 2, that is, it has only one screw blade 2. . The blade 2 has a notched tip, and digging blades 4, 4' are installed in the tip of the notch so as to face the rotating direction of the blade 2. In the figure, 5 indicates the center rod of the head 1a. , the rod 5
A spout 5a for dispensing mortar, cement milk, etc. is formed at the lower end of the screw, and an insertion portion 5b for connecting to the screw body is formed at the upper portion, as in the conventional case. FIGS. 3 to 7 show modified examples of the auger head 1a, and the auger head 1b in FIG. In the auger head 1c shown in FIG. 4, the rod 5 is extended further downward than in the example shown in FIG.

The head 1d shown in FIG. 5 is a rod 5 which is made longer like the head 1c, and the pitch of the blades 2 is shortened to make it longer, and the head 1d shown in FIG.
The head 1f in FIG. 7 has two parallel guide blades 7 and 7' instead of the guide blade 6 in the head 1b in FIG. 3, and the head 1f in FIG. 7 has the guide blade 6 in the head 1c in FIG. A guide blade 8 is provided which protrudes to intersect with the guide blade 8.

Install such an auger head into the screw body 9.
It is used in addition to the steel pipe casing 10, but as shown in FIG. 8, it is used in combination with the steel pipe casing 10. This casing 10 is provided with an excavating blade 11 at its lower end, and the excavating blade 11 may be a blade inserted by welding or the like, or one formed by cutting the lower end of the casing 10 into a sawtooth shape. Although not shown, screw blades may also be provided on the outer peripheral surface of the casing 10, in which case the excavation blade 11 will be implanted at the tip of the screw blade.

In FIG. 8, 9a is a blade on the side of the screw body 9, and the upper end of the blade 2 of the auger head 1b is connected to the lower end of this blade 9a. Further, in FIG. 8, three excavating blades 4, 4', and 4'' are installed at the tip of the blade 2 so as to face in the opposite direction to the excavating blade 11.

Next, an embodiment of the construction method of the present invention will be described in the case of erecting prefabricated piles.The earth auger equipped with the auger head 1b having only the blades 2 as shown in FIG. 8 is introduced into the casing 10. Then, the ground auger and the casing 10 are rotated in opposite directions to cut into the ground 12. At that time, as shown by arrow a in FIG. 9, the casing 10
The tip of the auger head 1b is placed slightly ahead of the auger head 1b. The earth and sand scraped by the excavating blades 4, 4', 4'' of the head 1b and the guide blade 6 within the casing 10 are moved upward along the blades 2, transferred to the blades 9a of the screw body, and transported upward. Note that when the excavating blades 4, 4', 4'' are hit by a boulder or the like, a force is applied that bends the head 1b in the escape direction, but the outer casing 10 excavates in advance, As a result, the auger head 1b can be prevented from actually bending since the area to be excavated by the auger has been cut off from the periphery to make it easier to excavate. When the guide blade 6 is provided, the possibility of further bending is reduced.

By the way, casing 10 and auger head 1
When the heads 1b and 1b are rotated in the same direction, the surrounding ground 12 is moved by the outer casing 10 to the head 1b
The head 1b is rotated in the same direction as the head 1b.
However, this mutual reversal eliminates this inconvenience, and the excavation reaction forces transmitted to the drive unit cancel each other out, which is advantageous for supporting the drive unit.

As described above, even when the ground 12 is dug and the support layer 13 is reached, the casing 10 is advanced as shown by the arrow b in FIG.
After cutting into the support layer 13, the head 1b is advanced so as to eliminate the distance difference between the head 1b and the casing 10, as shown by the arrow c in FIG.

In this way, the support layer 1 within the casing 10
3 is excavated by the head 1b, and since the support layer 13 is separated from the surrounding by the casing 10, even if it is very hard, it can be excavated reliably.

Furthermore, as another embodiment, when cutting the casing 10 into the support layer 13, the distance between the head 1b and the casing 10 may be gradually shortened, and both may be advanced so that the levels are finally made to match.

Next, with the casing 10 still cut into the ground as shown by arrow d in Figure 9, the earth auger is pulled out with or without rotation, and grounded as shown by arrow e in Figure 9 and arrow f in Figure 9. Precast piles 14 such as precast concrete piles or H-shaped steel are erected in the space excavated by the auger, and the gaps are grouted with cement milk, mortar, or the like.

In addition to erecting prefabricated piles as described above, the construction method of the present invention can be similarly applied to piles constructed on site.

As described above, the pile hole construction method of the present invention prevents earth and sand from clogging the cutter head or its vicinity when excavating a pile hole using an earth auger, and furthermore, it is possible to avoid clogging with earth and sand in the cutter head portion or the vicinity thereof, and to prevent the pile hole from being clogged with the surrounding area by using a casing in advance. The edges of the earth auger have been cut to make it easier to excavate and to prevent too much force from being applied to the auger head, allowing the earth auger to dig accurately without bending.

[Brief explanation of drawings]

Figure 1 is a front view of a conventional auger head;
Figures 2 to 7 are front views showing an example of a cutter head used in the construction method of the present invention, Figure 8 is an explanatory front view showing an example of the construction method of the present invention, and Figure 9 is a front view showing an example of a cutter head used in the construction method of the present invention. FIG. 1, 1a to 1f... Auger head, 2, 3...
...Blade, 4,4',4''...Drilling blade, 5...Rod, 5a...Spout, 5b...Joint insertion part,
6, 7, 7', 8... Guide blade, 9... Screw body, 9a... Vane, 10... Casing, 11
...Drilling blade, 12 ... Ground, 13 ... Supporting layer, 1
4... Ready-made pile.

Claims (1)

[Claims] The auger head is equipped with only one screw blade, and a cutting blade is planted in the notch at the tip of the blade in the direction of rotation of the blade, and the earth auger is connected to the auger head to the tip of the auger screw body. A pile hole creation method characterized by introducing the earth auger into an excavation casing having a digging blade at its tip, and cutting into the ground with the casing leading while rotating the earth auger and the casing in opposite directions.