JPH0649975B2 - Earth auger for cast-in-place piles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an earth auger used in a construction method for cast-in-place concrete piles, which is frequently used as a foundation for construction work.

(Prior art) As a construction method for cast-in-place piles, the Benoto construction method has been
Although there are a reverse construction method, an earth drill construction method, a deep foundation construction method, and the like, the earth auger of the present invention is similar to a conventional earth drill.

(Problems to be solved by the invention) In the earth drill method, as a general rule, hole wall protection is not carried out, but excavation is carried out by a rotating bucket in bare digging. When hole wall protection is required, bentonite or the like was used. It uses muddy water.

However, when the bucket is filled with excavated soil, the excavation work using the rotating bucket is performed by repeatedly pulling up the bucket to carry out the earth and sand and then inserting the bucket into the hole again. Therefore, there is a problem that the drilling work is prolonged for the time required to discharge the sediment in the bucket.

When muddy water such as bentonite is used to protect the hole walls, excavated earth and sand mix with bentonite, which may cause pollution if industrial waste, which is a mixture of these, is not treated appropriately. There was a problem that

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the present invention, a spiral screw blade is provided around the hollow shaft, and the outer periphery of the screw blade is parallel to the outer peripheral surface of the hollow shaft. A spiral band is provided to form the earth auger body, a spiral screw blade is provided around the hollow shaft, a drill bit is provided at the end of this screw blade, and a reverse flow that prevents the reverse flow of earth and sand excavated during reverse rotation is provided. A stop plate is provided near the tips of the screw blades to form an auger head, and the auger head is connected to the tip portion of the earth auger body to form an earth auger for cast-in-place pile.

(Operation) As described above, the earth auger of the present invention is an earth auger in which a spiral screw blade is provided around the hollow shaft, and a spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of the screw blade. Since it has a main body, the excavated earth and sand will be retained around the hollow shaft by the screw blades and the spiral band.

The earth auger body has a tip connected to an auger head provided with a check plate for preventing the backflow of earth and sand excavated during reverse rotation, so the earth auger is used to excavate the ground to a predetermined depth. After that, if the earth auger is reversed once and then the earth auger is pulled up, the earth and sand accumulated in the groove of the earth auger is prevented from flowing backward by the check plate, and the excavated soil is excavated over the entire length of the earth auger. It can be pulled up to the outside while being held in the groove. And when this earth auger is pulled up, bentonite is injected from the hole in the hollow shaft to replace the excavated soil and bentonite in the hole, and then the reinforcing bar is inserted into the hole, and then the tremie pipe is used to insert the bottom part. If more concrete is sequentially poured to replace the bentonite and the concrete, it is possible to continuously dig up to a predetermined depth with the earth auger, and by pulling up this earth auger, excavated soil in the pit And bentonite can be replaced, and if unreinforced, excavated soil can be directly replaced with concrete.

Therefore, according to the earth auger of the present invention, the working efficiency is remarkably improved, and when the earth auger is pulled up, the earth and sand are less likely to collapse in the hole, so that slime hardly remains at the bottom of the hole.

In addition, since mud water such as bentonite is statically replaced with excavated soil, it is not necessary to mix the excavated soil with bentonite to produce industrial waste that may cause pollution.
The excavated soil by the earth auger of the present invention is discharged to the outside without being mixed with bentonite or the like, so that the excavated soil is not disposed of and is effectively used as buried soil. It can also be used.

(Example) Hereinafter, the Example of this invention is described about drawing. 1 to 5 show an earth auger for cast-in-place piles according to the present invention.

In this embodiment, a spiral screw blade 2 (see FIG. 2) is provided around a hollow shaft 1 having a hole 1a at the center, and the screw blade 2 has an outer periphery parallel to the outer peripheral surface of the hollow shaft 1. The spiral band 3 is wound as shown in FIG. 1 and is fixed to the screw blade 2 by welding or the like to integrally form the earth auger body 4. Reference numeral 1b is a joint insertion shaft portion provided at the upper end portion of the hollow shaft 1, and 1c is a joint shaft cylinder portion provided at the lower end portion of the hollow shaft 1.

Further, as shown in FIGS. 1, 3, 4, and 5, a spiral screw blade 6 is provided around the hollow shaft 5 having a hole 5a at the center, and particularly, in the lower portion of the hollow shaft 5, the screw blade 6 may be formed as necessary. Reduce the pitch. An excavation bit 7 is provided at the lower end of the screw blade 6, and a check plate 8 for preventing the backflow of the earth and sand excavated at the time of reverse rotation is provided near the tip of the screw blade 6 to integrally form an auger head 9.

As shown in FIG. 4, for example, the check plate 8 is rotatably supported by a pin 11 on a bracket 10 protruding from the screw blade 6 as shown by an arrow A. It is located at the position 8 ', and when it is reversed, it rotates to the position shown in the solid line diagram 8 so that the earth and sand in the groove between the screw blades 6 do not flow backward due to excavation.

In the figure, 5b is a joint insertion shaft portion provided at the upper end of the hollow shaft 5, and the shaft portion 5b should be inserted into the joint shaft cylinder portion 1c of FIG. 1 to insert the two bolts 12. The earth auger main body 4 and the auger head 9 are connected to form an earth auger 13 for cast-in-place pile.

Next, the cast-in-place pile construction method using the above-described earth auger 13 of the present invention will be described with reference to FIG.

In the figure, 15 is the ground, 16 is a drilling machine, 17 is its crawler, 18 is a swivel mounted on the crawler 17, 19 is an outrigger, 20 is a leader standing vertically in front of the swivel 18, 21 is The back stay, 22 is a back tensioner, and 23 is a rotary drive device for an earth auger that is hung vertically on the front surface of the reader 20.

In this method, as shown in FIG. 6 (I), the drilling machine 16
Rotation drive device 23 that can be lifted up and down in front of the leader 20
Suspend the earth auger 13 below the
Push 13 into ground 15 while rotating 13.

By doing so, the earth and sand excavated through the excavation bit 7 at the lower end of the auger head 9 below the earth auger 13 is rolled up by the screw blades 6, and then enters between the screw blades 2 of the earth auger body 4. To do.

Since the earth auger 13 gradually penetrates into the ground 15 during this time, as a result, as shown in FIG. 6 (I), excavated earth and sand 24 in the groove between the screw blades 6 and 2 of the earth auger 13 in the ground 15 Is full.

Then, as shown in FIG. 6 (II), the drilling work is continued until the earth auger 13 reaches a predetermined depth. In the case of FIG. 6 (II), only one earth auger 13 is shown, but if the depth is not reached with only one earth auger, the earth auger main body 4 is sequentially connected to drill a hole. I'll do it.

Next, as shown in FIG. 6 (III), when the depth of the hole 25 reaches a predetermined depth, the earth auger 13 is once reversed. 4th when the auger head 9 of the Earth auger 13 reverses
As described above with reference to the figure, the non-return plate 8 has a two-dot chain line diagram 8 '.
From the position shown in Fig. 8 to the position shown in the solid line 8 to prevent backflow of the excavated earth and sand 24 trapped between the screw blades 6 and 6. Further, in this case, since the earth and sand 24 that is trapped between the screw blades 2 and 2 of the earth auger body 4 has the spiral band 3 in particular, the earth auger body 4 should be removed from the earth auger body 4 even after being pulled up to the ground. There is no.

When pulling up the earth auger 13, bentonite 26 is injected through the holes 1a and 5a in the hollow shafts 1 and 5 of the earth auger 13. Therefore, in this step, the earth and sand 24 excavated by pulling out the earth auger 13 is discharged to the outside, and the bentonite 26 is replaced in the excavated hole 25.

When the earth auger 13 is completely pulled out from the inside of the pit 25 as described above, the reinforcing bar 27 is then inserted into the bentonite 26 inside the pit 25 as shown in FIG. Place it in the position.

Then, as shown in FIG. 6 (V), the tremie pipe 28 is bored.
It is inserted into 25, and concrete 29 is sequentially placed from the bottom to replace bentonite 26 and concrete 29.

FIG. 6 (VI) shows the cast-in-place reinforced concrete pile completed as described above.

Further, in the above construction method, water may be injected instead of the bentonite 26 described above.

When the ground 15 is a loam layer or a silt layer where the excavated hole wall is unlikely to collapse, injection of bentonite or a liquid such as water after the excavation by the earth auger 13 may be omitted.

In addition, if it is not necessary to insert the reinforcing bar in the cast-in-place pile, use the earth auger 13 after
When pulling up 13, concrete may be poured directly from the hole in the hollow shaft.

As described above, the earth auger of the present invention is provided with the spiral screw blade 2 around the hollow shaft 1 and the spiral band 3 parallel to the outer peripheral surface of the hollow shaft on the outer periphery of the screw blade 2. Since the auger body 4 is provided, the excavated earth and sand 24 can be held by the screw blades 2 and the spiral band 3 without falling around the hollow shaft 1.

Further, since the auger head 9 provided with a check plate 8 for preventing the backflow of the earth and sand 24 excavated during reverse rotation is connected to the tip of the earth auger body 4, the ground auger 13 is used for the ground 15 After excavating the earth auger to a predetermined depth, once the earth auger 13 is reversed and then the earth auger 13 is pulled up, the earth and sand 24 accumulated in the groove of the earth auger 13 is prevented from flowing backward by the check plate 8. At the same time, the excavated soil 24 is pulled out to the outside while holding the excavated soil 24 in the trench over the entire length of the earth auger 13. When pulling up the earth auger 13, the holes 1a in the hollow shafts 1 and 5 and
The bentonite 26 is injected from 5a to replace the excavated soil 24 and the bentonite 26 in the pit 25, and then the rebar 27 is placed in the pit 25.
After inserting, by placing concrete 29 from the bottom by the tremie pipe 28 in order to replace the bentonite 26 and the concrete 29, it is possible to continuously drill to a predetermined depth by the earth auger 13. At the same time, the earth auger 13 is pulled up,
And bentonite 26 can be replaced, and in the case of no reinforcement, excavated soil 24 and concrete 29 can be directly replaced.

As described above, according to the earth auger 13 of the present invention, it is possible to continuously perform the drilling work, and as a result of the experiment, the efficiency is improved about twice as compared with the conventional earth drilling method.

(Effects of the Invention) Therefore, according to the earth auger of the present invention, work efficiency is remarkably improved, and when the earth auger is pulled up, since earth and sand are less likely to collapse in the hole, slime may remain at the bottom of the hole. Almost never. Therefore, the excellent effect that high quality cast-in-place piles can be obtained is obtained.

Further, according to the earth auger of the present invention, mud water such as bentonite can be statically replaced with excavated soil, so that excavated soil and bentonite are not mixed to produce industrial waste that may cause pollution. . And since the excavated soil by the earth auger of the present invention can be discharged outside without being mixed with bentonite etc., according to the earth auger of the present invention, the excavated soil can be disposed of and the excavated soil can be excavated. Soil can be effectively used as buried soil, etc., and it has excellent effects in terms of pollution prevention and economics.

[Brief description of drawings]

FIG. 1 is an overall view of an earth auger according to the present invention, FIG. 2 is a partial view showing a state in which the earth auger is being manufactured, FIG. 3 is a bottom view of FIG. 1, and FIG. 4 is an example of an auger head. FIG. 5 is a bottom view thereof, and FIGS. 6 (I) to (VI) are process explanatory views of the cast-in-place pile construction method using the earth auger of the present invention. DESCRIPTION OF SYMBOLS 1 ... Hollow shaft, 1a ... Hole 2 ... Screw blade, 3 ... Spiral band 4 ... Earth auger body, 5 ... Hollow shaft 5a ... Hole, 6 ... Screw blade 7 ... Drilling bit, 8 ... Check plate 9 ... Auger head, 13 ... Earth auger 15 ... Ground, 16 ... Drilling machine 20 ... Leader, 23 ... Rotary drive device 24 ... Excavated earth and sand, 25 ... Drilling hole 26 ... Bentonite, 27 ... Rebar 28 ... Tremy pipe, 29 ... Concrete

Claims (1)

[Claims] 1. A spiral auger is provided around a hollow shaft, and a spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of the screw vane to form an earth auger main body, and the earth auger body is formed around the hollow axel. A spiral screw blade is installed on
An excavation bit is provided at the end of this screw blade, and a check plate that prevents the backflow of the earth and sand excavated at the time of reverse rotation is provided near the tip of the screw blade to form an auger head. Earth auger for cast-in-place pile connected to the tip.