JPH0136989Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an auger screw for an earth auger that can employ the in-situ mixing method.

Recently, when constructing foundation piles using an earth auger, instead of the so-called replacement method in which concrete is poured after removing soil with an auger, the existing soil is treated as aggregate, and a cement solution is mixed and stirred into it. The use of in-situ mixing methods to reduce discharged mud is increasing. However, the configuration of this type of auger screw (hollow shaft type) currently in use merely has a forward excavation screw similar to an auger screw. That is, the screw with respect to this rotating shaft has a structure in which wings are attached in the same direction, so the degree of disturbance caused by rotation is poor, and compaction due to pressure against the surrounding wall of the borehole is also weak.
Therefore, a considerable amount of soil is still being dumped onto the ground. In this case, the biggest problem is that the cement solution is also pumped out along with the soil, making disposal of the remaining soil a nuisance and a problem of pollution. Of course, this results in the use of more cement than necessary, which is economically unsatisfactory.

In view of the above-mentioned circumstances, the present invention provides an auger screw with a screw that maximizes the kneading action and has a good degree of disturbance.

That is, the present invention is a hollow shaft type auger screw in which a forward screw portion and a reverse screw portion having an appropriate number of pitches are sequentially and alternately arranged from the lower end on the outer periphery of the rotating shaft portion. be.

Hereinafter, the present invention will be explained based on the drawings of embodiments.

Figures 1 and 2 show the use of a single shaft of an auger screw; 1 is a rotating shaft part that receives torque and has a cement injection hole 2 in the center;
Forward screw portions 3 and reverse screw portions 4 having an appropriate number of pitches (for example, 4 to 5 pitches each) are sequentially and alternately disposed on the outer periphery of the auger screw 5 from the lower end. In this case, when connecting the auger screws 5 one after another, the single auger screw 5 should be configured so that the forward screw part 3 and the reverse screw part 4 are adjacent to each other at the upper and lower positions of the connection part. Of course.

To explain this function, first, when auger excavation is performed using a single shaft, an appropriate number of auger screws 5 are connected using a known connecting means, and the upper ends of the auger screws 5 are supported by the leader part (not shown) of the earth auger machine. The auger head 7 is attached to the coupling portion of the drive device 6, and is provided with an auger head 7 having a solution spouting hole at the lower end of the auger screw 5.

Here, if the auger screw 5 is pushed down to the ground using a known method and rotated in the forward direction, the claws of the auger head 7 will advance while digging up the ground, and the cement liquid will be released from the injection port of the auger head 7. In addition, in this case, the reverse screw portion 4 is substantially reversed on the forward screw portion 3.
Combined with the pushing down action of
This stirred liquid is pressed against the excavation wall to create a soil cement wall. That is, in this auger screw 5, a forward screw part 3 and a reverse screw part 4 are arranged alternately from the bottom several pitches at a time, and the reverse screw part 4 performs a large presser kneading operation. By pressing and compacting the circumferential wall of the borehole, a substantially greater degree of disturbance is obtained, and the compaction wall is expanded without reducing the excavation speed. Therefore, the screw payout amount of the excavated soil is reduced by the expansion of the consolidation wall (soil cement wall), and since the forward and reverse screws 3 and 4 are arranged in several stages, this pressing compaction is improved. This is repeated over and over again, and as a result, there is almost no soil being discharged above the borehole mouth. It should be noted that if the blade angle of the reverse screw part 4 is made a little gentler than the blade angle of the forward screw part 3, the pressing effect will be better and it will be suitable for excavating hard ground.

Further, FIG. 1B shows an embodiment in which the spacing between the forward and reverse screw portions 3 and 4 is changed. That is, a reverse screw part 4 disposed above a forward screw part 3 is provided with a certain gap 8 in relation to the rotating shaft part 1, thereby forming a single-shaft auger screw 5. In this case, the gap 8 becomes a kind of thixotropic acting part of the stirring liquid, so it is suitable for excavating soils such as loamy and silt layers, and it is also possible to use muddy liquid instead of cement liquid.

FIG. 3 shows another embodiment using three auger screws. This is the so-called SMW
This is a soil cement continuous wall construction method called the construction method, and the configuration of this single auger screw 5 is as follows.
Like the single-shaft type, forward screw parts 3 and reverse screw parts 4 are arranged alternately. However, since this SMW method involves a type of overlapping drilling, a configuration is adopted in which parts of the blades of the forward and reverse screw parts 3 and 4 of the three auger screws 5 overlap, respectively. Therefore, in a single auger screw 5, between the forward screw part 3 and the following reverse screw part 4, there is no space between the reverse screw part 4 of the adjacent auger screw 5 or the forward screw part 4. A gap portion 8' with a pitch width l is provided so that a portion of the portion 3 faces and the rotation spheres overlap each other.

In this case, the upper end of each auger screw 5, which has three axes, is attached to a drive device 6 whose adjacent axes rotate in the opposite direction to each other, and the lower end of each auger screw 5 is equipped with a known auger screw. A head 7 is provided. At this time, the heads at both ends are arranged so as to be slightly ahead or behind the center head.

If excavation is performed in this state, the three axes will be integrated by the interference device, the rigidity will be great, and obstacles between the auger heads will be pushed away by the mutually reversing heads, and the auger will be mixed and stirred with the cement solution in the same way as above. This will create a continuous consolidation wall around the circumference of the borehole.

In addition, as in the conventional method, reinforcing bar cages and
Stressed materials such as H-shaped steel are erected.

As mentioned above, the auger screw of the earth auger of the present invention has an extremely high degree of disturbance by alternately arranging the screw structure in the forward screw part and the reverse screw part, which increases excavation efficiency.
In addition, a consolidated wall with high water-stopping properties is obtained. Therefore, not only the amount of soil discharged to the excavation mouth can be minimized, but also the use of cement can be minimized, which is economically advantageous. Furthermore, the present invention has a simple structure, and a head,
Since no changes are caused to the drive unit etc., it can be installed in conventional earth auger machines and has practical effects such as being handled in the same way.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a front view of the auger screw A and B, FIG. 2 is an explanatory diagram of the same in use, and FIG. 3 is an explanatory diagram of another embodiment. 1...Rotating shaft portion, 2...Cement injection hole, 3...
...forward screw section, 4...reverse screw section.

Claims (1)

[Scope of utility model registration request] This earth auger auger screw is a hollow shaft type auger screw in which forward screw parts and reverse screw parts with an appropriate number of pitches are sequentially and alternately arranged on the outer periphery of the rotating shaft part from the lower end.