JPH0336395A - Earth auger for cast-in-place pile and its auger head - Google Patents

Abstract

PURPOSE:To prevent earth from falling when pulling up the main body of an earth auger by installing a helical band on the outer periphery of a helical blade fixed to a hollow shaft, and also attaching to the end of the main body a head provided with a helical band and an elastic plate similar to those of the main body, and having a bottom plate. CONSTITUTION:An earth auger main body 4 is comprised of a screw blade 2 fixed around a hollow shaft 1 and a helical band 3 installed on the outer periphery of the blade. An auger head 9 provided with a screw blade 6 and a helical band 30 both similar to those of the main body 4, a drilling bit 31, a bottom plate 35 and an elastic plate 40 serving as a nonreturn valve is attached to the end of the main body 4. Earth is prevented from collapsing during drilling and is also prevented from falling when the auger is pulled up. Thus, earth remaining in the drilled hole is surely removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an earth auger and its auger head used in cast-in-place concrete shafts, which are often used as foundations in construction work.

(Conventional technology) Conventional methods for constructing cast-in-place piles include the Benotoe method,
There are reverse construction methods, earth drill construction methods, deep foundation construction methods, etc., but the present invention is relatively related to construction methods that are close to the conventional earth drill construction methods.

In the earth drilling method, as a general rule, hole walls are not protected, and the hole is dug using a rotating packet. When hole wall protection is required, muddy water using bentonite or the like is used.

However, in excavation work using a rotary packet, once the packet is full of excavated soil, the process of first pulling up the packet to carry the soil outside and then reinserting the packet into the hole is repeated. Therefore, there was a problem in that the drilling work was prolonged by the time required to discharge the earth and sand inside the packet.

In addition, when muddy water such as bentonite is used to protect the hole wall, the excavated earth and sand are mixed with bentonite, and the industrial waste that is a mixture of these substances can cause pollution if not properly treated. There was a problem with that.

In order to solve the above-mentioned problems, the present applicant first provided a grounding device in which a spiral screw blade was provided around a hollow shaft, and a spiral band was provided on the outer periphery of the screw blade, which was parallel to the outer peripheral surface of the hollow shaft. After excavating the ground to a predetermined depth using an earth auger with an auger head equipped with a check plate on the tip of the auger body to prevent the backflow of excavated earth and sand when the auger is reversed, the earth auger is reversed. When pulling up the earth auger together with the excavated soil, bentonite is injected through the hole in the hollow shaft to replace the excavated soil and bentonite in the borehole, and then, after inserting reinforcing bars into the borehole, the tremie pipe is concrete is poured sequentially from the bottom to replace bentonite and concrete;
We have applied for a cast-in-place pile construction method and its device (Japanese Patent Application No. 1-1174), which is based on related technology.

The outline will be explained below based on FIG. 5 to FIG. 1O.

Figures 5 to 9 show an embodiment of this earth auger for cast-in-place piles.

In this embodiment, a hollow shaft 1 having a hole 1a in the center is used.
A spiral screw blade 2 (see FIG. 6) is provided around the screw blade 2, and a spiral band 3 parallel to the outer peripheral surface of the hollow shaft 1 is wound around the outer periphery of the screw blade 2 as shown in FIG. The earth auger main body 4 is integrally formed by being fixed to the screw blade 2 by welding or the like. Note that 1b is the hollow shaft 1
The joint insertion shaft part lc provided at the upper end is a joint shaft cylinder part provided at the lower end of the hollow shaft 1.

Further, as shown in Figs. 5.7 and 8.9, spiral screw blades 6 are provided around the hollow shaft 5 having a hole 5a in the center, and the screw blades 6 are provided especially in the lower part of the hollow shaft 5 as necessary. Reduce 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 excavated earth and sand when the screw blade is reversed is provided near the tip of the screw blade II6 to integrally form an auger head 9.

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

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

Next, a cast-in-place pile construction method using the earth auger 13 configured as described above will be explained 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 vertically placed in front of the swivel 18, and 21 is a In the backstay, 22 is a back tensioner, and 23 is a rotary drive device for an earth auger suspended from the front of the leader 20 so as to be able to rise and fall freely.

As shown in FIG. 10 (1), this construction method involves suspending an earth auger 13 below a rotary drive device 23 that is movable up and down on the front surface of a leader 20 of a drilling machine 16, and rotating this earth auger 13. Push it into the ground 15 while doing so.

In this way, the earth and sand excavated through the excavation bit 7 at the lower end of the auger head 9 at the bottom of the earth auger 13 is rolled up by the screw blades 6, and then enters between the screw blades 2 of the earth auger main body 4. do.

During this time, the earth auger 13 gradually penetrates into the ground 15, and as a result, as shown in FIG.
The groove between the screw blades 6 and 2 of the earth auger 13 in 5 is filled with excavated earth and sand 24.

Then, as shown in Figure 1O (II), the earth auger 1
3. Continue drilling until the specified depth is reached. 7th 1st
In the case of diagram O (If), only one earth auger 13 is shown, but if the specified depth cannot be reached with only one earth auger, connect the earth auger bodies 4 one after another and drill the hole. good.

Next, as shown in FIG. 10 (III), when the depth of the borehole 25 reaches a predetermined depth, the earth auger 13
Reverse. When the auger head 9 of the earth auger 13 is reversed, the check plate 8 rotates from the position shown by the chain double-dashed line 8' to the position shown by the solid line 8, as described above with reference to FIG. Excavated earth and sand stuck in 24
prevent backflow. In this case, the earth auger body 4
The earth and sand 24 stuck between the screw blades 2 and 2 does not fall off from the earth auger body 4 even after the earth auger body 4 is pulled up to the ground, especially because of the spiral band 3.

Note that when this earth auger 13 is pulled up, 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 process, the earth and sand 24 excavated by pulling out the earth auger 13
is discharged to the outside, and bentonite 26 is replaced in the borehole 25.

Once the earth auger 13 has been completely pulled out of the borehole 25 as described above, reinforcing bars 27 are inserted into the bentonite 26 in the borehole 25 and placed in a predetermined position, as shown in FIG. 10 (TV). Place it at the position.

Next, as shown in FIG. 10(V), the tray ξ-pipe 28 is inserted into the borehole 25, and the concrete 29 is sequentially poured from the bottom.
is placed to replace bentonite 26 and concrete 29.

FIG. 10 (Vl) shows the cast-in-place reinforced concrete shaft completed as described above.

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

Further, if the ground 15 is a loam layer or a silt layer, and the wall of the excavated hole is difficult to collapse, injection of liquid such as bentonite or water after the earth auger 13 excavates the hole may be omitted.

Furthermore, if there is no need to insert reinforcing bars into the cast-in-place pile, concrete may be placed directly through the hole in the hollow shaft of the earth auger 13 when the earth auger 13 is pulled up after the hole has been dug. .

As mentioned above, in this construction method, a spiral screw blade jiB, 2 is provided around the hollow shaft 1, and a 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 auger body 4 is used, the excavated earth and sand 24 is held around the hollow shaft 1 by the screw blades 2 and the spiral band 3 without falling off.

Further, an auger head 9 is connected to the tip of the earth auger body 4, and the auger head 9 is provided with a check plate 8 that prevents the backflow of the excavated earth 24 when the earth auger is reversed. After digging, the earth auger 13 was reversed and then pulled up, so the earth and sand 2 accumulated in the groove of the earth auger 13 were removed.
4 is prevented from flowing backward by the check Fi8, and
The excavated soil 24 is held in the groove over the entire length of the earth auger 13 and is pulled up to the outside. When the earth auger 13 is pulled up, bentonite 26 is injected through the holes 1a and 5a in the hollow shafts 1 and 5 to replace the bentonite 26 with the excavation ±24 in the borehole 25, and then the bentonite 26 is injected into the borehole 25. After inserting reinforcing bar 27 into
Since the concrete 29 is poured sequentially from the bottom through the pipe 28 to replace the bentonite 26 and the concrete 29, this construction method allows the earth auger 13 to continuously excavate holes to a predetermined depth. ,
By pulling up this earth auger 13, the excavation hole 25
Bentonite 26 can be replaced with excavation ± 24 inside, and in the case of unreinforced steel, excavation ± 24 and concrete 29 can also be directly replaced.

As mentioned above, according to this method, the earth auger 13 can perform continuous drilling work, and as a result of experiments, an efficiency improvement of approximately twice was achieved when compared with the conventional earth drilling method. Ta.

(Problems to be Solved by the Invention) As mentioned above, the construction method and device shown in FIGS. There is no spiral band for retaining the soil, and the check plate 8 that prevents the backflow of the excavated soil 24 when the earth auger 13 reverses is installed at a position considerably recessed from the tip of the excavation bit 7. Therefore, after the drilling by the earth auger 13 is completed, the hole shown in Fig. 10 (
As shown in III), there is a problem in that when the earth auger 13 is pulled up, the excavated earth and sand once held at the lower end of the auger head 9 may collapse to the bottom of the borehole 25 in some cases.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, a spiral screw blade is provided around a hollow shaft, and a spiral screw blade is provided on the outer periphery of the screw blade 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 spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of the screw blade, and a spiral band parallel to the outer peripheral surface of the hollow shaft is provided around the hollow shaft. Along with providing a drilling bit at the end,
A bottom plate is provided on the excavation bit and the portion in front of it except for an appropriate area, and an elastic plate capable of covering the void in the bottom plate is provided inside the bottom plate with one end fixed to the bottom plate, and the excavation bit is fixed to the bottom plate. An auger head is formed so as to be openable and closable with respect to the bottom plate surface, and this auger head is connected to the tip of the earth auger body to constitute an earth auger for a cast-in-place pile.

Further, in the present invention, double spiral screw blades are provided around the hollow shaft, spiral bands parallel to the outer peripheral surface of the hollow shaft are provided on the outer periphery of these screw blades, and spiral bands are provided at the ends of the screw blades, respectively. Along with providing a drilling bit,
A bottom plate is provided on these drilling bits and a portion other than an appropriate area in front thereof, and an elastic plate capable of covering the void in the bottom plate is provided inside the bottom plate with one end fixed to the bottom plate. The auger head is configured such that the auger head can be freely opened and closed with respect to the bottom plate surface.

Furthermore, it is preferable that the spiral band provided on the outer periphery of the screw blade of the earth auger body and the auger head is fixed to the screw blade while being biased upward.

(Function) As described above, in the present invention, a spiral screw blade is provided around the hollow shaft of the earth auger body and the auger head, and a spiral screw blade is provided on the outer periphery of the screw blade parallel to the outer peripheral surface of the hollow shaft. Since the spiral band is provided, the excavated soil is held around the hollow shaft by the screw blades and the spiral band.

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

Note that if the spiral band provided on the outer periphery of the earth auger body and the screw blade of the auger head is fixed to the screw blade by being biased upwardly, the ability to prevent the excavated soil from collapsing can be further improved.

Further, in the present invention, double spiral screw blades are provided around the hollow shaft of the auger head, a spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of these screw blades, and an end of the screw blade is provided with a spiral band parallel to the outer peripheral surface of the hollow shaft. A drilling bit is provided in each part, and a bottom plate is provided in the part excluding these drilling bits and an appropriate area in front of the drilling bit, and an elastic plate capable of covering the void in the bottom plate is placed inside the bottom plate, and one end thereof is attached to the bottom plate. Since the elastic plate is fixed to the auger head when digging a hole, the elastic plate bends upward to accommodate the soil excavated by the bit inside the auger head, but when the hole is finished and the auger head is pulled up, the elastic plate bends upward. When the condition returns, the opening provided in the bottom plate can be automatically closed to prevent excavated soil from falling into the auger head.

Therefore, by using this auger head, it is possible to reliably eliminate the remaining soil inside the excavation tag.

(Example) Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 4. In FIG.

FIG. 1 shows an embodiment of the 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 l having a hole 1a in the center, and a spiral band 3 parallel to the outer peripheral surface of the hollow shaft 1 is wound around the outer periphery of the screw blade 2. At the same time, the earth auger main body 4 is integrally formed by being fixed to the screw blade 2 by welding or the like. Note that 1b is a joint insertion part provided at the upper end of the hollow shaft 1, and 1c
is a shaft cylinder portion for a joint 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 provided doubly around the hollow shaft 5 having a hole 5a in the center, and the hollow shaft 5 is provided around the outer periphery of these screw blades 6.
A spiral band 30 is provided parallel to the outer circumferential surface of the auger head, and a drilling bit 31 is provided at each end of the screw blade 6 to be pivotally supported by a shaft 32 provided horizontally at the bottom of the auger head.

This excavation bit 31 is divided into two pieces, left and right, and its planar shape has a plurality of notches 31a on one side of a rectangular shape (see Fig. 2).
(see b)), and the notch 31
By fitting the brackets 33 fixed to the auger head body into the fitting portions a and passing the shaft 32 through the fitting portions, the drilling bit 31 is pivotally supported in a tiltable manner. Note that 34 is a bracket protruding from the center of the bottom of the auger head so as to be interposed between the left and right excavation bits 31.

The excavation bit 31 has a front edge 31b formed to have a wedge-shaped vertical cross section, and has a stepped protrusion 31c protruding from the rear thereof.

Also, the installation position of the drilling bit 31 and an appropriate range in front of the tip 31b side of the drilling bit 31 (in this embodiment, the range of about 90 degrees of intersection angle with the center point of the hollow shaft 5 as the base point)
The bottom plate 35 of the auger head is attached to the hollow shaft 5 except for the
and the lower end of the spiral band 30, and the drilling bit 31 is fixed to the plane of the bottom plate 35 as shown in FIG.
) as shown by the arrows B in FIG.
is fixedly provided at the lower end of the screw blade 6.

Further, 37 indicates the spiral band 30 at the outer peripheral portion of the bottom plate 35.
38 is a bottom circumferential plate formed in a circle with a constant width so as to be continuous with the bottom circumferential plate 37, and 38 is a side bit protruding diagonally downward from the lower end of the spiral band 30 and the bottom circumferential plate 37. It is.

Then, an elastic plate 40 (see FIG. 3(6)) having a planar shape curved into an approximately 1/4 arc shape capable of covering the void 39 (see FIG. 4(a)) of the bottom plate 35 is made of rubber or the like. The elastic plate 40 is made of an elastic material, and one end 40a of the elastic plate 40 is attached to the base 41.
The elastic plate 40 is fixed on the opposite end edge of the drilling bit 31 of the bottom plate 35 via the elastic plate 40, and is arranged so that the free end 40b of the elastic plate 40 can overlap the lower tip of the screw blade 6.

Note that 42 (see FIG. 3(a)) is one end portion 4 of the elastic plate 40.
A stop plate 43 is a set screw for fixing Oa.

Further, as shown in FIGS. 4(a) and 4(b), 44 is a partition plate provided near the lower end inside the hollow shaft 5, and 44a is a partition plate provided on the partition plate 44 at two locations with a phase of 180 degrees. /4 This is a circular discharge port, and one side of a sector-shaped rubber valve 45, which is made by dividing a circular rubber plate into eight equal parts through the center, is inserted into the discharge port 44a through two strip-shaped washers 46. Partition vi4 with screw 47
4 is attached to the opening edge of the hollow shaft 5 so that a fluid such as bentonite or the like 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 indicates a joint insertion shaft portion provided at the upper end of the hollow shaft 5. This shaft portion 5b is inserted into the joint shaft cylindrical portion IC shown in FIG. By inserting bolts 12, the earth auger body 4 and the auger head 9 are connected to form an earth auger 13 for a cast-in-place pile.

When the earth auger 13 configured as described above is used to rotatably excavate the ground, the excavation bit 31 excavates the ground in the state shown in FIG. 3(a), so in this case the elastic plate 40 is in the state shown in FIG. 3(a). The free end 40b is bent upward as shown in the two-dot chain diagram.

Therefore, the excavated earth and sand are transferred between the excavation bit 31 and the elastic plate 4.
0 and is accommodated in the auger head 9.

When the excavation is finished, the rotation of the earth auger 13 is stopped and the earth auger 13 is lifted up. As shown in the solid line diagram in (a), the excavated earth and sand can be prevented from falling by restoring it to the horizontal state.

Note that the cast-in-place pile construction method carried out 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, so a description of the construction method will be omitted.

(Effect of the invention) As described above, in the present invention, the earth auger main body 4,
Further, spiral screw blades 2, 6 are provided around the hollow shaft 1.5 of the auger head 9, and a spiral band 3.3 parallel to the outer peripheral surface of the hollow shaft 1, 5 is provided on the outer periphery of the screw blades 2, 6. 30, the excavated soil is held around the hollow shaft 1.5 by the screw blades 2, 6 and the spiral band 3.30.

In particular, in the present invention, the auger head 9 also has a spiral band 30.
Since this auger head is provided, the holding power of the excavated soil is increased, and the collapse of the excavated soil can be further reduced.

In addition, as in the embodiment shown in FIGS. 1 to 4, the earth auger main body 4
If the spiral band 3.30 provided on the outer periphery of the screw blade 2.6 of the auger head 9 is biased upward and fixed to the screw blades 2, 6, the collapse prevention performance of the excavated soil is further improved.

Further, in the present invention, a double spiral screw blade 6 is provided around the hollow shaft 5 of the auger head 9, and a spiral band 30 parallel to the outer peripheral surface of the hollow shaft 5 is provided on the outer periphery of each screw blade 6. A drilling bit 31 is provided at each end of the screw blade 6, and a bottom plate 35 is provided at a portion other than these drilling bits 31 and an appropriate area in front of the drilling bit 31, and a hollow space 39 of the bottom plate 35 is covered. Since the elastic plate 40 is provided inside the bottom [35 with one end 40a thereof fixed to the bottom plate 35, the elastic plate 40 bends upward when digging a hole and accommodates the soil excavated by the bit 31 inside the auger head 9. However, when the auger head 9 is pulled up after drilling is completed, the elasticity 140 returns to the horizontal state and automatically closes the opening provided in the bottom 135 to prevent excavated soil from falling inside the auger head 9. be able to.

Therefore, by using this auger head 9, it is possible to reliably eliminate the remaining soil in the dugout.

As described above, according to the present invention, an excellent effect can be obtained in that the cast-in-place pile method can be carried out easily, quickly and accurately compared to conventional methods.

[Brief explanation of drawings]

Figure 1 is an overall view of the earth auger according to the present invention, and Figure 2 (
A) is an elevational view of the auger head at the bottom, FIG. 3(C) is a bottom view thereof, FIG.
4(a) is a partial view showing the lower end of the hollow shaft of the auger head, FIG. 4(6) is a cross-sectional view taken along line X-X, and FIG. Fig. 6 is a partial view showing the state of the earth auger in the process of manufacture, Fig. 7 is a bottom view of Fig. 5, Fig. 8 is an elevational view showing an example of the auger head, Fig. 9 is The bottom view and FIGS. 10(1) to (Vl) are explanatory diagrams of the process of the cast-in-place pile construction method using the earth auger of FIG. 5. 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... Boring machine 20... Leader 23... Rotation drive device 24... Excavated earth and sand 25...・Drill hole 26...
・Bentonite 27...Reinforcing bar 28...Tremy tube 29...Concrete 30...Spiral body
31...Drilling bit 35...Bottom plate
36...Supporting member 37...Bottom circumferential plate 3
8... Side bit 39... Blank space 40
... Elastic plate 44 ... Partition plate 45 ... Rubber valve 47 ... Screw 44a ... Discharge port 46 ... Washer

Claims (1)

[Claims] 1. A spiral screw blade is provided around a hollow shaft, and a spiral band parallel to the outer circumferential surface of the hollow shaft is provided on the outer periphery of the screw blade to form an earth auger body. A spiral screw blade is provided around the shaft, a spiral band parallel to the outer peripheral surface of the hollow shaft is provided on the outer periphery of the screw blade, a drilling bit is provided at the end of the screw blade, and the drilling bit and its A bottom plate is provided in a portion excluding an appropriate area in front, an elastic plate capable of covering the empty space of the bottom plate is provided inside the bottom plate with one end fixed to the bottom plate, and the drilling bit is placed against the bottom plate surface. An earth auger for cast-in-place piles, which has an auger head that can be opened and closed freely, and this auger head is connected to the tip of the earth auger body. 2. A double spiral screw blade is provided 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 a drilling bit is provided at each end of the screw blade. At the same time, a bottom plate is provided on the part excluding the drilling bit and an appropriate area in front of it,
An auger head for a cast-in-place pile, in which 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, and the excavation bit can be opened and closed with respect to the bottom plate surface. 3. The earth auger body for cast-in-place piles according to claim 1 or 2, wherein a spiral band provided on the outer periphery of the screw blade of the earth auger body and the auger head is fixed to the screw blade while being biased upward. and Ogre Head.