JPH0772468B2 - Earth auger and its auger head for cast-in-place pile - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an earth auger and an auger head thereof used in the construction of cast-in-place concrete piles, which are frequently used as a foundation in 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 present invention is relatively related to a construction method close to the conventional earth drill construction method.

In principle, the earth drill method does not protect the hole wall, but excavates it with a rotating bucket in a bare digging process. When it is necessary to protect the hole wall, muddy water containing bentonite is used.

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

In order to solve the above-mentioned problems, the present applicant has previously provided a ground provided with a spiral screw blade around the hollow shaft and a spiral band parallel to the outer peripheral surface of the hollow shaft on the outer periphery of the screw blade. Use the earth auger with an auger head that has a check plate to prevent backflow of earth and sand excavated at the time of reversing at the tip of the auger body, excavate the ground to a predetermined depth, and then reverse the earth auger once. When pulling up the earth auger together with the excavated soil, bentonite is injected from the hole in the hollow shaft to replace the excavated soil and bentonite in the borehole, and then the reinforcing bar is inserted into the borehole, followed by the tremie pipe. Placing concrete sequentially from the bottom to replace the bendnite and concrete,
We applied for a cast-in-place pile construction method and its equipment (Japanese Patent Application No. 1-1174), which is based on the technology related to this.

The outline will be described below with reference to FIGS. 5 to 10.

5 to 9 show one embodiment of the earth auger for this cast-in-place pile.

In this embodiment, a spiral screw blade 2 (see FIG. 6) 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. 5, 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. 5, 7, 8 and 9, 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 Reduce the pitch. And this screw blade 6
An excavation bit 7 is provided at the lower end of the screw, and a check plate 8 for preventing a backflow of the excavated earth and sand during reverse rotation is provided with a screw blade 6
The auger head 9 is integrally formed by being provided near the tip of the auger head 9.

As shown in FIG. 8, 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 indicated by ′, and when it is rotated in reverse, it is rotated to the position shown in the solid line diagram 8 so that the earth and sand in the grooves 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 cylindrical portion 1c of FIG. 5 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, a cast-in-place pile construction method using the earth auger 13 configured as described above 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 construction method, as shown in FIG. 10 (I), an earth auger 13 is hung below a rotary drive device 23 provided on the front surface of a leader 20 of a drilling machine 16 so as to be lifted and lowered, and the earth auger 13 is rotated. While pushing into the ground 15.

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. 10 (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. 10 (II), the drilling work is continued until the earth auger 13 reaches a predetermined depth. Fig. 10 (II)
In the case of, only one earth auger 13 is shown.
If the earth auger of the book alone does not reach the predetermined depth, the earth auger main body 4 may be sequentially connected to form a hole.

Next, as shown in FIG. 10 (III), when the depth of the hole 25 reaches a predetermined depth, the earth auger 13 is once reversed. When the auger head 9 of the earth auger 13 rotates in the reverse direction, the check plate 8 rotates from the position of the chain double-dashed line diagram 8'to the position of the solid line diagram 8 as described above with reference to FIG. Prevents the backflow of excavated earth and sand 24 that is stuck in. 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 detached 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 hole 25 as described above, next, as shown in FIG. 10 (IV),
A reinforcing bar 27 is inserted into the bentonite 26 in the hole 25 and is arranged at a predetermined position.

Then, as shown in FIG. 10 (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.

Figure 10 (VI) shows the cast-in-place reinforced concrete pile completed as described above.

Further, in this 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, in this construction method, the spiral screw blade 2 is provided around the hollow shaft 1, and the spiral band 3 parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of the screw blade 2.
Since the earth auger main body 4 provided with is used, the excavated earth and sand 24 is removed by the screw blade 2 and the spiral band 3 from the hollow shaft 1
It will be held around without falling off.

Further, an auger head 9 provided with a check plate 8 for preventing the backflow of the earth and sand 24 excavated at the time of reverse rotation is connected to the tip of the earth auger body 4, and the ground auger 13 is used for ground 15
After excavating the earth auger to a predetermined depth, the earth auger 13 was once reversed and then the earth auger 13 was pulled up. 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, bentonite 26 is injected from the holes 1a and 5a in the hollow shafts 1 and 5 to replace the excavated soil 24 and the bentonite 26 in the drill hole 25, and then in the drill hole 25. After inserting the reinforcing bar 27 into the steel, the tremie pipe 28 was used to sequentially place concrete 29 from the bottom to replace the bentonite 26 and the concrete 29. It is possible to dig up to the depth of, and by pulling up this earth auger 13,
The excavated soil 24 and the bentonite 26 in the inside can be replaced, and in the case of being unreinforced, the excavated soil 24 and the concrete 29 can be directly replaced.

As mentioned above, according to this construction method, since the earth auger 13 can continuously perform the drilling work, as a result of the experiment, the efficiency is about doubled as compared with the conventional earth drill construction method. It was

(Problems to be Solved by the Invention) As described above, the construction method and apparatus shown in FIGS. 5 to 10 are epoch-making, but the excavated soil is formed on the outer peripheral portion of the screw blade 6 of the auger head 9. Since there is no spiral band to hold the earth auger 13 and the mounting position of the check plate 8 that blocks the backflow of the earth and sand 24 excavated when the earth auger 13 is reversed, is considerably deep from the tip of the excavation bit 7, When the earth auger 13 finishes the drilling and the earth auger 13 is pulled up, as shown in FIG. 10 (III), in some cases, the excavated sand once held at the lower end of the auger head 9 is There was a problem that it could collapse to the bottom of 25.

(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 screen blade is parallel to the outer peripheral surface of the hollow shaft. The earth auger body is formed by providing a spiral band, 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. An excavating bit is provided at the end, and a bottom plate is provided at a portion excluding this excavating bit and an appropriate area in front of the excavating bit, and an elastic plate that can cover the void of this bottom plate is provided on the inside of the bottom plate with one end as the bottom plate. The drill bit is fixedly provided, and the auger head is formed so as to be openable and closable with respect to the bottom plate surface, and the auger head is connected to the tip portion of the earth auger main body to cast in place. A ground auger for the.

Further, in the present invention, a spiral screw blade is provided in a double manner around the hollow shaft, a spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of these screw blades, and the screw blade is provided at each end of the screw blade. With a drill bit,
A bottom plate is provided in a portion excluding these drill bits and an appropriate area in front thereof, and an elastic plate capable of covering a void in the bottom plate is provided inside the bottom plate with one end fixed to the bottom plate. The auger head is configured to be openable and closable with respect to the bottom plate surface.

It is preferable that the spiral band provided on the outer periphery of the screw blade of the earth auger main body and the auger head is biased upward with respect to the screw blade and fixed.

(Operation) As described above, in the present invention, the spiral auger is provided around the earth auger body and the hollow shaft of the auger head, and the spiral of the screw vane is parallel to the outer peripheral surface of the hollow shaft. Since the band is provided, the excavated earth and sand will be held around the hollow shaft by the screw blade and the spiral band.

In particular, in the present invention, since the spiral band is also provided on the auger head, the holding force of the excavated soil at the auger head portion is increased, and the collapse of the excavated soil can be further reduced.

If the spiral band provided on the outer circumference of the screw blade of the earth auger body and the auger head is biased upward and fixed to the screw blade, the collapse preventing performance of the excavated soil is further improved.

Further, in the present invention, a spiral screw blade is provided around the hollow shaft of the auger head in a double manner, and a spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of the screw blade, and the end of the screw blade is provided. Each of the parts is provided with a drill bit, and a bottom plate is provided in a part excluding the drill bit and an appropriate area in front of the drill bit, and an elastic plate capable of covering a void in the bottom plate is provided on the inner side of the bottom plate at one end thereof. The elastic plate bends upward to accommodate the excavated soil by the bit inside the auger head during the drilling, but when the drilling is completed and the auger head is pulled up, the elastic plate is horizontal. By returning to the state, the opening provided in the bottom plate can be automatically closed to prevent the excavated soil in the auger head from falling.

Therefore, by using this auger head, it is possible to surely eliminate the residual soil in the drill hole.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. In the figure, the same reference numerals as those used in the previous description denote the same elements.

FIG. 1 shows an embodiment of an earth auger for cast-in-place piles according to the present invention.

In this embodiment, a spiral screw blade 2 is provided around a hollow shaft 1 having a hole 1a in the center, and a spiral band 3 parallel to the outer peripheral surface of the hollow shaft 1 is provided on the outer periphery of the screw blade 2.
Is wound and fixed to the screw blade 2 by welding or the like to integrally form the earth auger body 4. Note that
Reference numeral 1b denotes a joint insertion portion provided at the upper end of the hollow shaft 1, and 1c denotes a joint shaft cylinder portion provided at the lower end of the hollow shaft 1.

Further, as shown in detail in FIGS. 2 to 4, spiral screw blades 6 are doubly provided around the hollow shaft 5 having a hole 5a at the center, and the outer periphery of the hollow shaft 5 is provided on the outer periphery of these screw blades 6. A spiral band 30 parallel to the surface is provided, and the screw blade 6
A drill bit 31 is provided at each end of the shafts and is pivotally supported by a shaft 32 that is provided laterally at the bottom of the auger head.

This drill bit 31 is divided into two pieces on the left and right, and its planar shape is a plurality of cuts 31a on one side of a rectangular shape (Fig. 2 (b)).
(Refer to FIG. 3), and the brackets 33 fixed to the auger head main body are fitted into the notches 31a, respectively, and the shaft 32 is passed through the fitting portions, whereby the drill bit 31 can be tilted. Support. Reference numeral 34 is a bracket projecting at the center of the bottom portion of the auger head so as to be interposed between the left and right excavation bits 31.

Further, the drill bit 31 has a front edge portion 31b formed so that its vertical cross-sectional shape is a wedge shape, and a stepped projecting piece 31c is projectingly provided on a rear portion thereof.

Also, the mounting position of the drill bit 31 and the drill bit 31
The bottom plate 35 of the auger head is attached to the lower end of the hollow shaft 5 in a portion excluding an appropriate range in front of the tip portion 31b side (in this embodiment, a range of an angle of intersection of about 90 degrees from the center point of the hollow shaft 5). And the lower end of the spiral band 30 are fixedly provided, and the excavation bit 31 can be opened and closed with respect to the plane of the bottom plate 35 as shown by an arrow B in FIG. 3 (a), and at the time of excavation rotation of the earth auger. In order to hold the excavation bit 31 in the excavation posture, a support member 36 that abuts against the protrusion 31c is fixedly provided at the lower end of the screw blade 6.

Further, 37 is a bottom circumferential plate formed in a cylindrical shape with a constant width so as to be continuous with the spiral band 30 on the outer periphery of the bottom plate 35, and 38 is a lower end of the spiral band 30 and the bottom circumferential plate 37. It is a lateral bit projecting obliquely downward on the part.

An elastic plate 4 having a plane shape curved in a substantially 1/4 circular arc shape capable of covering the space 39 (see FIG. 4A) of the bottom plate 35.
0 (see FIG. 3 (b)) is formed of an elastic material such as rubber, and one end 40a of this elastic plate 40 is attached to the bottom plate 35 via the pedestal 41.
It is fixed on the opposite end edge of the excavating bit 31, and is arranged so that the free end 40b of the elastic plate 40 can overlap the lower end of the screw blade 6.

Reference numeral 42 (see FIG. 3 (a)) is a contact plate for fixing one end 40a of the elastic plate 40, and 43 is its set screw.

Further, as shown in FIGS. 4 (a) and (b), 44 is a hollow shaft 5
It is a partition plate provided near the lower end of the
It is a discharge port of approximately 1/4 circular shape provided at two places of 80 degree phase, and one side of a fan-shaped rubber valve 45, which is divided into 8 through a circular rubber plate, is attached to this discharge port 44a. 2 via plate-shaped washer 46
Attach to the opening edge of the partition plate 44 with a screw 47 of the book,
A fluid such as bentonite that is fed through the inside of the hollow shaft 5 can be discharged.

The auger head 9 as shown in FIGS. 2 and 3 is formed as described above.

In FIG. 2 (a), reference numeral 5b denotes a joint insertion shaft portion provided at the upper end of the hollow shaft 5, and the shaft portion 5b is fitted into the joint shaft cylinder portion 1c of FIG. By inserting the bolt 12, the earth auger body 4 and the auger head 9 are connected to form the earth auger 13 for cast-in-place pile.

When the earth auger 13 configured as described above is used to rotate and excavate the ground, the excavating bit 31 excavates the ground in the state of FIG. 3 (a), and in this case, the elastic plate 40 is shown in FIG. 3 (a).
It is bent as shown by the two-dot chain line and the free end portion 40b thereof rises upward.

Therefore, the excavated earth and sand is accommodated in the auger head 9 through the space between the excavation bit 31 and the elastic plate 40.

When the excavation is finished, the rotation of the earth auger 13 is stopped and the earth auger 13 is pulled up, and the elastic plate 40
Is to prevent the excavated earth and sand from falling by restoring the elasticity by itself and the weight of the excavated earth and sand accumulated upward to restore the horizontal state as shown by the solid line diagram in Fig. 3 (a). You can

Since the cast-in-place pile construction method using the earth auger 13 of the present invention configured as described above is the same as that described above with reference to FIG. 10, the description of the construction method is omitted.

(Effects of the Invention) As described above, in the present invention, the earth auger body 4,
And spiral screw blades 2, 6 are provided around the hollow shafts 1, 5 of the auger head 9, and the screw blades
A spiral band 3,30 parallel to the outer peripheral surface of the hollow shaft 1,5 is provided on the outer circumference of 2,6.
Since the above is provided, the excavated earth and sand is held around the hollow shafts 1 and 5 by the screw blades 2 and 6 and the spiral bands 3 and 30.

Particularly, in the present invention, since the spiral band 30 is also provided on the auger head 9, the holding force of the excavated soil at the auger head portion is increased, and the collapse of the excavated soil can be further reduced.

The earth auger body 4 as in the embodiment of FIGS.
If the spiral bands 3 and 30 provided on the outer circumferences of the screw blades 2 and 6 of the auger head 9 are biased upward and fixed to the screw blades 2 and 6, the collapse prevention performance of excavated soil is further improved.

Further, in the present invention, double screw blades 6 are provided around the hollow shaft 5 of the auger head 9, and spiral bands 30 parallel to the outer peripheral surface of the hollow shaft 5 are provided on the outer periphery of the screw blades 6, respectively. A drill bit 31 is provided at each end of the screw blades 6, and a bottom plate is provided at a portion excluding the drill bit 31 and an appropriate area in front thereof.
Since the elastic plate 40 which is provided with 35 and covers the void 39 of the bottom plate 35 is provided by fixing one end 40a of the elastic plate 40 to the bottom plate 35 inside the bottom plate 35, the elastic plate 40 bends upward at the time of digging. The excavated soil by the bit 31 is stored inside the auger head 9, but when the auger head 9 is pulled up after the excavation is completed, the elastic plate 40 returns to the horizontal state and the opening provided in the bottom plate 35 is automatically opened. It is possible to prevent the excavated soil in the auger head 9 from falling down by closing it.

Therefore, if this auger head 9 is used, it is possible to surely eliminate the residual soil in the drill hole.

As described above, according to the present invention, an excellent effect that the cast-in-place pile construction method can be performed easily, quickly and accurately as compared with the conventional construction method is obtained.

[Brief description of drawings]

FIG. 1 is an overall view of an earth auger according to the present invention, FIG. 2 (a) is an elevational view of a lower auger head, FIG. 2 (b) is a bottom view thereof, and FIG. FIG. 4A is a bottom view of the same, FIG. 4A is a partial view showing the lower end of the hollow shaft of the auger head, and FIG. 4B is its XX line. FIG. 5 is a general view of a conventional earth auger, FIG. 6 is a partial view showing a state of the earth auger in the process of being manufactured, FIG. 7 is a bottom view of FIG. 5, and FIG. An elevation view showing an example of the auger head, FIG. 9 is a bottom view thereof, and FIGS. 10 (I) to (VI) are process explanatory views of the cast-in-place pile construction method using the earth auger of FIG. 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 …… Non-return plate 9 …… Auger head, 13 …… Earth auger 15 …… Ground, 16 …… Drilling machine 20 …… Leader, 23 …… Rotary drive device 24 …… Excavated earth and sand, 25 …… Drill hole 26 …… Bentonite, 27 …… Reinforcing bar 28 …… Tremy tube, 29 …… Concrete 30 …… Helical body, 31 …… Drilling bit 35 …… Bottom plate, 36 …… Support member 37 …… Bottom circumferential plate, 38 …… Side bit 39 …… Vacancy, 40 …… Elastic plate 44 …… Partition plate, 44a …… Discharge port 45 …… Rubber valve, 46 …… Washer 47 …… Screw

Claims (3)

[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
A spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer circumference of the screw blade, a drill bit is provided at the end of the screw blade, and a bottom plate is provided on the drill bit and a portion excluding an appropriate area in front of the drill bit. An elastic plate capable of covering the void of the bottom plate is provided inside the bottom plate with one end fixed to the bottom plate, and the excavating bit is opened and closed with respect to the bottom plate surface to form an auger head. An earth auger for cast-in-place piles, which is formed by connecting an auger head to the tip of the earth auger body. 2. A double screw screw blade 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 these screw blades, and each end of the screw blade is excavated. In addition to providing the bit, a bottom plate is provided in a portion excluding these drill bits and an appropriate area in front of the drill bit, and an elastic plate capable of covering the void of the bottom plate is fixed to the bottom plate at one end thereof inside the bottom plate. An auger head for a cast-in-place pile provided with the excavating bit openable and closable with respect to the bottom plate surface. 3. The earth auger for cast-in-place pile according to claim 1, wherein a spiral band provided on the outer periphery of the screw blade of the earth auger body and the auger head is biased upward and fixed to the screw blade. .