JP5380064B2 - Pile hole drilling method and pile hole drilling head - Google Patents

Description

  The present invention relates to a pile hole excavation method and a pile hole excavation head used when excavating various pile holes.

  When excavating a substantially vertical pile hole in the ground and burying a reinforcing steel cage or ready-made pile in the pile hole to construct a pile structure, an excavation rod was used. The excavation rod has an excavation head for excavating the ground at the lower end, and the excavation head has an excavation blade at the lower end of the spiral blade, and has a structure for digging the ground like a cone (for example, Patent Documents 1 to 3). 4).

  However, the excavation head having this structure is effective when the diameter is small, but the excavation efficiency is low and the excavation head is large when the diameter is large. Furthermore, with this type of excavation head, only one diameter of the pile hole can be excavated with one excavation head, and when an enlarged rooted portion is formed, the diameter expansion mechanism becomes complicated. was there.

Therefore, the applicant has developed a drilling head in which a swingable drilling arm is attached to a horizontal axis, and has solved such a problem (for example, Patent Document 5).
JP-A-8-302688 JP 2004-293267 A JP 2006-207320 A JP2007-162215 JP-A-8-338020

  In the case of the excavation head provided with the swingable excavation arm, a sufficient excavation speed may not be obtained depending on the ground conditions, such as a relatively small-diameter pile hole or a solid ground. It needed some ingenuity.

  However, in the present invention, since the swinging arm having the second excavating blade formed at the tip is provided above the first excavating blade with the spiral blade, the above-mentioned problem can be achieved without making the second excavating blade a special structure. The point was solved.

That is, this invention is a head for excavation attached to the tip of an excavation rod installed in a rotating device on the ground, and is a pile hole excavation head characterized by considering all the following conditions.
(1) A second head main body having a connection portion with the excavation rod at the upper end is provided above the first excavation head main body.
(2) a lower end portion of the first head body, providing a first digging edge which can drill the entire Kuiana bottom with diameter D _0.
(3) In the first head body, a spiral blade is provided continuously above the first excavation blade.
(4) A horizontal axis is installed on the second head body in a diametrical direction with respect to the axis of the excavation rod, and an excavation arm having a second excavation blade at the tip of the horizontal axis is swingable. Install. The second head main body and the excavating arm have a structure not provided with a power mechanism for swinging.
(5) When the diameter of the rotation trajectory of the second excavation blade is D when the excavation rod is rotated,
D ₀ <D
It was.
(6) The height of the cutting edge of the second excavating blade is positioned below the upper end of the spiral blade in a state where the excavating arm hangs downward.

In the above, when the excavating rod is rotated forward and the excavating arm swings to excavate the diameter D, the height position of the second excavating blade is positioned at the height near the upper end of the spiral blade. Thus, a pile hole excavation head comprising both head bodies and excavation arms. Also, drilling arm, the Kaido軌traces of the second digging edge of when the forward rotation drilling rod and the diameter D _1, the diameter the rotation locus of the second excavating blade when the reverse rotation of the drill rod D ₂ If
D ₁ <D ₂
The pile hole excavation head is characterized by being configured as follows.

Further, the invention of the excavation method is a method for excavating a pile hole by attaching an excavation head to the tip of a excavation rod installed in a rotating device on the ground, and the pile hole is performed by the following procedure Excavation method.
(1) The excavation head has a first excavation blade capable of excavating a pile hole bottom with a diameter D ₀ at the tip of the spiral blade, and is provided above the spiral blade in a direction perpendicular to the axis of the excavation rod. Provided on the excavating arm that swings around the support shaft, provided with a second excavating blade at the tip of the excavating arm, and with the excavating arm hanging downward, the height of the cutting edge of the second excavating blade, It was comprised so that it might be located below the upper end of the said spiral blade .
(2) First, the excavation arm is set to the first swing angle, the excavation rod is rotated forward, and the ground is excavated with the first excavation blade and the spiral blade.
(3) At this time, the excavation arm swings based on the setting, and with the lowering of the excavation head, the height position excavated by the phase position excavation blade and the spiral blade is the second excavation blade, while a larger Kuianakabe drilling pile holes wall of D _1.
(4) Once drilling shank of the pile bore diameter D _1, then, the excavating arm is set to the second swing angle, the drill rod and the normal rotation or reverse rotation, the Kuiana An enlarged rooting portion having a diameter D ₂ (D ₂ > D ₁ ) is formed at the lower end portion of the shaft portion by the second excavation blade.
(5) When the excavation of the enlarged root is completed, the excavation rod and excavation head are lifted to the ground.

Another invention of the excavation method is a method of excavating a pile hole by attaching an excavation head to the tip of a excavation rod installed in a rotating device on the ground, which is performed in the following procedure. It is a pile hole excavation method.
(1) The excavation head has a first excavation blade capable of excavating a pile hole bottom with a diameter D ₀ at the tip of the spiral blade, and is provided above the spiral blade in a direction perpendicular to the axis of the excavation rod. Provided on the excavating arm that swings around the support shaft, provided with a second excavating blade at the tip of the excavating arm, and with the excavating arm hanging downward, the height of the cutting edge of the second excavating blade, It comprises so that it may be located below the upper end of the said spiral blade .
(2) First, the excavation arm is set to the first swing angle, the excavation rod is rotated forward, and the ground is excavated with the first excavation blade and the spiral blade.
(3) At this time, the excavating arm swings based on the setting, and with the lowering of the excavating head, the height position excavated by the phase position excavating blade and the spiral blade is the second excavating blade, A pile hole wall with a diameter D is excavated while expanding the pile hole wall.
(4) When the excavation of the pile hole is completed, the excavation rod and excavation head are lifted to the ground.

  Since the second head main body provided with the excavating arm having the second excavating blade at the tip is swingably provided above the first head main body having the first excavating blade with the spiral blade, the first excavating blade and Since the clot that could not be crushed by the spiral blade is crushed by the excavating arm with the second excavating blade, the residual clot can be remarkably reduced and can be removed even if there are underground obstacles.

  Depending on the soil quality, the excavation arm is closed and the first excavation blade and the spiral blade are excavated mainly, or the excavation arm is opened wide and the second excavation blade is excavated, and the soil condition and pile to be excavated Depending on the structure of the hole, the excavation efficiency of the pile hole can be increased with one excavation head.

(1) The excavation head 30 of the present invention is used by being connected to the lower end of an excavation rod 45 that is coupled to a rotating device (auger) of a ground pile driving machine. The excavation head 30 has a rod connecting portion 13 with an excavation rod 45 above the first head main body 1 having the first excavation blades 6, 6 and connects the second head main body 11 having the second excavation blade. Install and configure (FIG. 1).

(2) The first head body 1 has two spiral blades 3 and 3 attached to the first head main body 1 with a 180 ° phase shift, and the first excavation blades 6 and 7 are attached to the lower ends 4a and 4a of the spiral blades 3 and 3, respectively. Fix it downward. The maximum outer diameter of the row 8 of the spiral blades 3 and 3 or the first excavation blades 6 and 7 is formed by the diameter _D01 .

(3) The rod connecting portion 13 connected to the excavation rod 45 is formed at the upper end of the second head main body 11, and the excavation rod is formed at the upper end of the second head main body 11 at a right angle with the shaft 46 of the excavation rod 45. Oscillating shafts (horizontal axes) 15 and 15 are formed in the diameter direction of 45 and in the horizontal direction. The upper end 18 of the excavation arm 17 having the second excavation blades 21, 21 formed at the lower end is attached to the swing shaft 15 so as to be swingable.
The height of the cutting edge 21 a of the second excavating blade 21 is located below the upper end 4 of the spiral blade 3 with the excavating arm 17 hanging downward. When the second head body 11, drill rod 45 is reversely rotated, the drilling arm 17 swings to the other side, to allow drilling diameter D _2, a stopper for restricting the maximum swing angle of the digging arm 17 23, 23 are attached, and a stopper receiving recess 24 into which the biased stopper 23 can be fitted is formed on the back surface of the excavating arm 17.
The excavation head 30 of this invention is comprised as mentioned above (FIG. 1). In this excavation head 30, the shaft portion 41 of the pile hole 40 can be excavated with a diameter D ₁ (FIGS. 2A and 2B), and the enlarged rooted portion 42 can be excavated with a diameter D ₂ (FIGS. 2C and 2D). .

(4) In the drilling head 30, the shaft portion 41 of diameter _{D 1,} can drilled Kuiana 40 having an enlarged root consolidated portion 42 of diameter _{D 2} (FIG. 2), the conventional Similarly, this Kuiana 40, Foundation piles are constructed by burying ready-made piles and steel bars. In this case, it may be a D ₁ without enlarging the root hardened portion. Further, the maximum diameter D ₀₁ of the spiral blade 3,3, is set smaller than the inner diameter of the ready-made piles to be used, can be applied to medium-drilling method.

  An embodiment of the excavation head 30 of the present invention will be described based on the drawings.

(1) The excavation head 30 according to the present invention has a rod connecting portion 13 connected to the excavation rod 45 at the upper end continuously from the first head body 1 having the first excavation blades 6 and 6, and The second head main body 11 having two excavating blades is connected and configured.

(2) The first head body 1 has two spiral blades 3 and 3 attached to the first head main body 1 with a 180 ° phase shift, and the first excavation blades 6 and 7 are attached to the lower ends 4a and 4a of the spiral blades 3 and 3, respectively. Fix it downward. The spiral blades 3 and 3 are formed to have a diameter D ₀₁ at the upper end 2 of the first head body 1 and a diameter D ₀₂ (D ₀₂ <D ₀₁ ) at the lower end 2 a of the first head body 1.

The first excavation blades 6 and 6 are arranged at the lower end 2a (diameter D ₀₂ ) of the first head body 1 so that the bottom of the pile hole 40 (pile hole shaft portion 41) to be excavated can be excavated without fail in the row 8. Yes. Further, the first excavating blades 6 and 7 are composed of a central blade 7 located at the center (near the rod shaft 46) along the row 8 and peripheral blades 6 and 6 on the outer peripheral side thereof. The central blade 7 is formed in a thick plate shape along the row 8 with the tip sharpened and the blade tip directed in the vertical direction. The cutting edge 6a of the peripheral blade 6 is an extension line that extends obliquely downward along the direction in which the spiral blade 3 of the spiral blade 3 rotates downward, and is formed slightly downward.

  The number of turns of the spiral blade 3 is about 90 degrees (about "1/4" circumference) from the upper end 4 to the lower end 4a, but it is sufficient if it is formed at least about "1/5" circumference (72 degrees). .

  A connecting convex portion with the second head main body 11 is formed on the upper end portion of the first head main body 1 (not shown).

(3) The second head main body 11 has a quadrangular prism shape, and the upper end portion is formed with the rod connecting portion 13 that is connected to the lower end portion of the excavation rod 45, and the lower portion is formed with the bulging portions 12 and 12 in the substantially horizontal direction. And the connection recessed part (not shown) connected with the connection convex part of the 1st head main body 1 is formed in a lower end part (lower end part of the bulging parts 12 and 12).

  A swing shaft is provided at the upper end of the second head body 11 so as to be substantially perpendicular to the axis of the second head body 11 (axis 46 of the excavation rod 45), in a substantially horizontal direction passing through the axis, and in the diameter direction of the excavation rod 45. (Horizontal axis) 15 and 15 are formed. The oscillating shafts 15 and 15 can be either integrated or divided. The upper end portion 18 of the excavation arm 17 having the second excavation blades 21, 21 formed at the lower end portion is attached to the swing shaft 15 so as to be rotatable (swingable). The excavating arm 17 has a shape bent toward the outside so that the excavating arms 17 and 17 approach the intermediate portion 18a and leave at the lower end portions 18b and 18b. The 2nd excavation blades 21 and 21 are attached along the direction which extends the lower end part 18b diagonally downward. Therefore, the second excavation blade 21 is formed with the cutting edge 21a obliquely downward (extended in the axial direction of the excavation arm) and outward (radial with respect to the rod shaft 46).

  Further, the height of the cutting edge 21a of the second excavating blade 21 overlaps with the height of the spiral blade 3 with the excavating arm 17 hanging downward (located between the upper end 4 and the lower end 4a). 6 and 6 are located immediately above. Therefore, when the excavation rod 45 rotates forward and the excavation arm 17 swings to one side, the second excavation blade 21 is at a height position overlapping the vicinity of the upper end 4 of the spiral blades 3 and 3.

  The swing shaft 15 is formed in the same direction as the row 8 in which the first excavation blades 6 and 7 of the first head body 1 are provided (that is, the direction of the lower end 4a of the spiral blade 3). Further, the swing shaft 15 is formed at an angle orthogonal to the row 9 of the upper end 4 of the spiral blade 3, that is, the swinging arc (fan-shaped) surface of the excavating arm 17 and the row 9 are formed in parallel. Therefore, the height position of the tip of the excavation arm 17 (tip 21a of the second excavation blade 21) and the height position of the upper end 4 of the spiral blade 3 can be made as close as possible.

The bulging portion 12 of the second head body 11, when the drill rod 45 is reversely rotated, the drilling arm 17 by a predetermined angle swing, to allow drilling diameter D _2, the maximum swing of the drilling arm 17 Attach stoppers 23 and 23 for regulating the angle. The stopper 23 has a structure that protrudes and protrudes from the surface of the second head body 11 and is biased to the protruding state. On the back surface of the excavating arm 17 (the surface facing the second head main body 11), a stopper receiving recess 24 into which the biased stopper 23 can be fitted is formed.

  Further, in the second head body 11, the stirring plates 25, 25 for stirring and kneading are arranged at a position orthogonal to the swing shaft 15 with the upper and lower positions of the stirring plates 25, 25 being inclined. ing.

(4) The excavation head 30 of the present invention is configured as described above. In the excavation head 30, the shaft portion 41 of the pile hole 40 can be excavated with the diameter D ₁ and the enlarged rooted portion 42 can be excavated with the diameter D ₂ .

  Further, the excavation head 30 is not provided with a driving means such as hydraulic pressure or air pressure for swinging the excavation arms 17, 17. The excavation arms 17, 17 have their own weight, centrifugal force, soil applied to the excavation arm 17. It can be freely swung by pressure.

(5) Other configurations

  In the above-described embodiment, the connection head and the connection head are provided so that the first head body 1 and the second head body 11 can be disassembled. The first head main body 1 and the second head main body 11 can be integrally configured so as to be disassembled (not shown).

  In the above-described embodiment, a stopper that restricts the swing angle of the excavation arm 17 when the excavation rod 45 rotates forward can be provided (not shown). In this case, the excavation diameter of the shaft portion 41 of the pile hole 40 corresponding to the set swing angle is set. Therefore, in this case, since the diameter of the shaft portion 41 can be defined by excavation with the first excavation blade 21 of the excavation arm 17, the diameter of the spiral blade 3 or the diameter of the first excavation blades 6, 6 is set to the pile hole 40. It is also possible to set the diameter smaller than the diameter of the shaft portion 41 (not shown).

Further, in the above embodiment, the diameter of the lower end 4a in diameter of the spiral blade 3,3 has been a D _02, as the same as the diameter D ₀₁ of the upper end 4 may be the same diameter in the helical blade 3,3 overall length (Figure 3). In this case, the lower end 4a of the spiral blade 3,3, since in 4a is formed a first digging edge 6, 7 are arranged in the diameter _{D 01} entire first digging edge 6,6. In this case, the central blade 7 is omitted and the structure is similar to that of the peripheral blade 6 (FIG. 3B).
In the case of the excavation head 30 having the structure shown in FIG. 3, the shaft portion 41 of the pile hole 40 has a diameter D ₁ (FIGS. 4A and 4B), and the enlarged rooting portion 42 has a diameter D ₂ , as in the above embodiment. (Fig. 4 (c) (d)). Moreover, this excavation head 30 is suitable for the ground which is comparatively hard.

  In the above embodiment, the number of turns of the spiral blades 3 and 3 is the amount of “1/4” rotation (90 degrees), but it can also be “1” rotation (360 degrees) (FIG. 5). FIG. 6).

Moreover, in the said Example, the stopper which controls the rocking | fluctuation of the excavation arm 17 at the time of forward rotation can also be provided. For example, drill rod 45 when the drilling arm 17 on one side and forward rotation is swung, the second head body stopper 27,27a for restricting the swing angle of the drilling diameter D ₁ in contact with the drilling arm 17 11 provided (FIGS. 5 (a) FIG. 6 (a)), when the drill rod 45 is drilled arm 17 on the other side rotates in the reverse direction to swing, the swing drilling diameter D ₂ in contact with the drilling arm 17 Stoppers 28 and 28a for restricting the moving angle can be provided on the second head body 11 (FIGS. 5B and 6B).

  Next, the use of the excavation head 30, that is, the invention of the excavation method of the present invention will be described.

(1) At a predetermined pile hole excavation position, the rod connecting portion 13 of the excavation head 30 is connected to the lower end of the excavation rod 45 whose upper end is connected to an auger (not shown), so that the excavation head 30 is brought to the excavation position. Lower (Figure 1).

(2) When the first excavating blades 6 and 7 are put on the ground and the auger is rotated forward, the excavating rod 30 is also rotated forward, and the first excavating blades 6 and 7 and the spiral blades 3 and 3 are engaged with the ground. while, drilling Kuiana diameter _{D 01} (FIG. 2 (a)). At this time, the side wall of the pile hole is a rough wall surface according to the spiral blade.

(3) Since the auger is rotating forward, the excavating arms 17 and 17 are swung to one side by their own weight and centrifugal force. Furthermore, due to the earth pressure of the excavated soil supplied upward from the spiral blades 3, 3, the second excavating blades 21, 21 swing with an opening of the diameter D ₁ , and smooth the rough side wall while grinding the rough pile hole side wall. The pile hole walls are leveled by the plates 25 and 25. At this time, since the first excavation blades 21 and 21 cut the pile hole wall immediately above the upper ends 4 and 4 of the spiral blades 3 and 3, the pile hole can be excavated efficiently.

(4) Once excavation to a predetermined depth, once the auger stops rotating, from the lower end of the pile hole 40 (lower end of the enlarged root consolidation part 42 to be formed) or the upper end of the expansion root consolidation part 42 to be excavated From the height, reverse the auger. The reverse rotation of the auger, drilling arms 17, 17 swung to the opposite side, it opens to a diameter D ₂ while scraping Kuianakabe, stopper 23 and the stopper receiver 24 is fitted, keeping the diameter D ₂ if you ask while moving the drill head 30 vertically and can form an enlarged root consolidated portion 42 of diameter _{D 2} (FIG. 2 (c) (d)) .

(5) Once the predetermined enlarged root fixing portion 42 has been formed, once the auger is stopped and the excavating rod 45 is pushed down and rotated forward, a gap is formed between the second head body 11 and the excavating arm 17. As a result, the fitting between the stopper 23 and the stopper receiver 24 is released, so that the excavation arms 17 and 17 can be suspended, and the excavation head 30 can be lifted to the ground together with the excavation rod 45 (FIG. 1).

  In this state, the excavating arms 17 and 17 with the second head main body 11 and the second excavating blade 21 are flat and accommodated in the spiral blades 3 and 3, so that the excavating arm 17 and the like are pile wall walls when pulled up. Will not disturb you.

(6) When the excavation head 30 is pulled up, the pile hole 40 is filled with cement milk according to a conventional method, and after the excavation head 30 is pulled up, a ready-made pile is embedded in the pile hole 40 (not shown). .

  In addition, according to the conventional method, a reinforcing bar can be inserted into the pile hole 40 and filled with concrete (not shown).

It is an Example of the pile hole excavation head of this invention, (a) is a front view, (b) is a right view. In the use state of the pile hole excavation head of the present invention, (a) is a plan view during normal rotation, (b) is a front view during normal rotation, (c) is a plan view during reverse rotation, and (d) is reverse It is a front view at the time of rotation. In another embodiment of the pile hole drilling head of the present invention. (A) is a front view, (b) is a right side view. In the state of use of another pile hole excavation head of the present invention, (a) is a plan view during forward rotation, (b) is a front view during forward rotation, (c) is a plan view during reverse rotation, (d) FIG. 3 is a front view during reverse rotation. It is a front view of the Example of the other pile hole excavation head of this invention, (a) at the time of forward rotation, (b) represents the time of reverse rotation, respectively. It is a front view of the Example of the other pile hole excavation head of this invention, (a) at the time of forward rotation, (b) represents the time of reverse rotation, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st head main body 2 The upper end 2a of a 1st head main body The lower end 3 of a 1st head main body 4 Spiral blade 4 The upper end 4a of a spiral blade 6 The lower end 6 of a spiral blade 1st excavation blade (peripheral blade)
6a Cutting edge 7 of the first excavating blade Central blade (first excavating blade)
8 Row of first excavating blades (row of lower end 4a of spiral blade)
9 rows (upper end 4 of spiral blade)
11 Second head main body 12 Swelling portion 13 of second head main body 13 Rod connecting portion 15 Oscillating shaft 17 Excavation arm 18 Upper end portion 18a of excavation arm Intermediate portion 18b of excavation arm Lower end portion 21 of excavation arm Second excavation blade 21a 2 Cutting edge 23 of excavation blade Stopper 24 Stopper receiving recess 27, 27a Stopper 28, 28a Stopper 25 Stirring plate 30 Pile hole excavation head 40 Pile hole 41 Pile hole shaft part 42 Pile hole enlarged root part 45 Excavation rod 46 Excavation rod Axis of

Claims (5)

A pile drilling head, which is an excavation head attached to the tip of a drilling rod installed on a rotating device on the ground, characterized by considering all of the following conditions.
(1) A second head main body having a connection portion with the excavation rod at the upper end is provided above the first excavation head main body.
(2) a lower end portion of the first head body, providing a first digging edge which can drill the entire Kuiana bottom with diameter D _0.
(3) In the first head body, a spiral blade is provided continuously above the first excavation blade.
(4) A horizontal axis is installed on the second head body in a diametrical direction with respect to the axis of the excavation rod, and an excavation arm having a second excavation blade at the tip of the horizontal axis is swingable. Install. The second head main body and the excavating arm have a structure not provided with a power mechanism for swinging.
(5) When the diameter of the rotation trajectory of the second excavation blade is D when the excavation rod is rotated,
D ₀ <D
It was.
(6) The height of the cutting edge of the second excavating blade is positioned below the upper end of the spiral blade in a state where the excavating arm hangs downward. When the excavating rod is rotated forward and the excavating arm swings to excavate with a diameter D, the heads of both heads are positioned so that the height position of the second excavating blade is located near the upper end of the spiral blade. The pile hole excavation head according to claim 1, wherein the excavation arm is constituted. Drilling arm, the drill rod positively rotated Kaido軌traces of the second digging edge when the diameter D _1, and the rotation locus of the second excavating blade when the reverse rotation of the drill rod and the diameter D ₂ If
D ₁ <D ₂
The pile hole excavation head according to claim 1, wherein the pile hole excavation head is configured as follows . A method for excavating a pile hole by attaching an excavation head to the tip of an excavation rod installed in a rotating device on the ground, which is performed by the following procedure.
(1) The excavation head has a first excavation blade capable of excavating a pile hole bottom with a diameter D ₀ at the tip of the spiral blade, and is provided above the spiral blade in a direction perpendicular to the axis of the excavation rod. Provided on the excavating arm that swings around the support shaft, provided with a second excavating blade at the tip of the excavating arm, and with the excavating arm hanging downward, the height of the cutting edge of the second excavating blade, It was comprised so that it might be located below the upper end of the said spiral blade .
(2) First, the excavation arm is set to the first swing angle, the excavation rod is rotated forward, and the ground is excavated with the first excavation blade and the spiral blade.
(3) At this time, the excavation arm swings based on the setting, and with the lowering of the excavation head, the height position excavated by the phase position excavation blade and the spiral blade is the second excavation blade, while a larger Kuianakabe drilling pile holes wall of D _1.
(4) Once drilling shank of the pile bore diameter D _1, then, the excavating arm is set to the second swing angle, the drill rod and the normal rotation or reverse rotation, the Kuiana An enlarged rooting portion having a diameter D ₂ (D ₂ > D ₁ ) is formed at the lower end portion of the shaft portion by the second excavation blade.
(5) When the excavation of the enlarged root is completed, the excavation rod and excavation head are lifted to the ground. A method for excavating a pile hole by attaching an excavation head to the tip of an excavation rod installed in a rotating device on the ground, which is performed by the following procedure.
(1) The excavation head has a first excavation blade capable of excavating a pile hole bottom with a diameter D ₀ at the tip of the spiral blade, and is provided above the spiral blade in a direction perpendicular to the axis of the excavation rod. Provided on the excavating arm that swings around the support shaft, provided with a second excavating blade at the tip of the excavating arm, and with the excavating arm hanging downward, the height of the cutting edge of the second excavating blade, It comprises so that it may be located below the upper end of the said spiral blade .
(2) First, the excavation arm is set to the first swing angle, the excavation rod is rotated forward, and the ground is excavated with the first excavation blade and the spiral blade.
(3) At this time, the excavating arm swings based on the setting, and with the lowering of the excavating head, the height position excavated by the phase position excavating blade and the spiral blade is the second excavating blade, A pile hole wall with a diameter D is excavated while expanding the pile hole wall.
(4) When the excavation of the pile hole is completed, the excavation rod and excavation head are lifted to the ground.

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