JP2003247229A - Drilling and agitating equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide drilling and agitating equipment uniformly injecting an improving agent into the soil and sufficiently agitating it. <P>SOLUTION: This drilling and agitating equipment is rotatably provided with a tubular outer shaft 40 and an inner shaft 31 inside the outer shaft 40 respectively, and provided with a double-pipe shaft 30 having improving agent feed passages 41 and 32 in the outer shaft and the outer shaft respectively, an agitating vane 42a provided in the outer shaft, a drilling vane 33 provided in the inner shaft, and a first improving agent delivery port 35 in the drilling vane. The drilling vane may be provided with a second improving agent delivery port 35. The agitating vane is provided with a first agitating vane 43a installed in the outer shaft and a second agitating vane 44a attached to the first agitating vane approximately in parallel in the rotating direction in the plane view and slantly attached to the outer shaft center in the side view. This equipment is provided with a plurality of agitating vanes and preferably, the respective second agitating vanes are so disposed that, when being rotated once, the respective loci drawn by the respective second agitating vanes are mutually different. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hole drilling and agitating device for drilling a hole in the ground, discharging an improving agent, and stirring with soil to improve the soil.

[0002]

2. Description of the Related Art Conventionally, when improving a soft ground or improving contaminated soil, a boring machine is used to drill a hole in the ground and inject a soil improvement agent into the soil to improve the soil and the improvement agent. There is a method for improving soil by stirring. Various devices have been proposed for the device. As one example, Japanese Patent Laid-Open No. 6-193048 and Japanese Patent Publication No.
There is one disclosed in Japanese Patent Laid-Open No. 100934.

FIG. 10 is a schematic side view of a self-propelled underground boring and stirring apparatus 50 showing a general underground structure forming construction described in JP-A-6-193048. Figure 10
At the reader 52, which is held almost vertically on the carriage 51,
Auger 5 attached so that it can move vertically along the
3, an underground mixer 60 is provided at the tip.
A swivel joint 54 is provided above the auger 53, and is connected to a modifying agent supply device 55 installed on the ground by a supply pipe 56. When working, the auger 53
While drilling the ground with the modifier feed device 55 to the auger 5
The improving agent is supplied to the tip of No. 3, and the improving agent is discharged into the soil in the underground mixer 60 and stirred with the soil to improve the soil.

FIG. 11 is a partial sectional perspective view of an underground mixer 60 disclosed in Japanese Patent Laid-Open No. 6-193048. In FIG. 11, a drum casing 63 is attached to an outer shaft 61 which is rotationally driven by a drive device (not shown) via a plurality of inward stirring blades 62. An outer stirring blade 65 is attached to a hollow inner shaft 64 that is rotatably inserted in the outer shaft 61 and is rotationally driven in the opposite direction to the outer shaft 61 by the drive unit. And the outward stirring blades 65 are alternately arranged in the axial direction. A bit-type stirring blade 66 is attached to the tip of the inner shaft 64, and the inward stirring blade 6 of the inner shaft 64 is attached.
A plurality of improving agent injection nozzles 67 are opened in the side surface portion between the 2 and the outward stirring blade 65 and the tip side surface portion.
The improving agent supplied to the passage 68 provided therein is injected from the improving agent injection nozzle 67 into the soil.

The bit type stirring blade 66 driven by a driving device moves downward while drilling the ground, and sprays the modifying agent from the modifying agent injection nozzle 67 into the soil. At this time, the inward stirring blade 62 and the outward stirring blade 65 rotate in mutually opposite directions to stir the soil and the improving agent.

FIG. 12 is a schematic side sectional view of a double pipe hole kneading machine 70 disclosed in Japanese Patent Publication No. 7-100934. In FIG. 12, an outer pipe shaft 73 is provided on the outer periphery of the inner shaft 72.
Is fitted to form a double pipe shaft 71, and the inner shaft 7
2 and the outer tube shaft 73 rotate separately.
A plurality of stirring and kneading blades 74 are provided on the outer surface of the outer tube shaft 73, and holes 75 for discharging the liquid improving agent are formed on the side surface of the outer tube shaft 73. A drill bit 76 is provided at the tip of the inner shaft 72, and a plurality of lower stirring and kneading blades 77 are provided on the outer surface of the inner shaft 72 above the drill bit 76. The inner shaft 72 is provided with holes 78 through which the improving agent is discharged at the tip and side surfaces thereof.

In the double pipe drilling and kneading machine 70, the inner shaft 72 is rotated by high torque to be drilled by the drilling bit 76, and the outer pipe shaft 7
Lower while rotating 3 at high speed. At this time, the outer tube shaft 7
The improver is discharged from holes 75 and 78 provided in the inner shaft 72 and the inner shaft 72, respectively, and the soil and the improver are mixed and kneaded by the stirring and kneading blade 74 and the lower stirring and kneading blade 77.

[0008]

However, the above-mentioned Japanese Patent Laid-Open No. 6-193048 and Japanese Patent Publication No. 7-100934.
In the configuration of the conventional hole agitating device disclosed in Japanese Patent Laid-Open Publication No. 2005-242242, an injection port for injecting the improving agent into the soil (the improving agent injection nozzle 67 in the first conventional technique, or the hole 75 in the second conventional technique,
78) is the inner shaft 64, or the inner shaft 72 and the outer pipe shaft 7, respectively.
Since the modifier is provided on the side surface of No. 3, the modifier is largely supplied to the periphery of those shafts, but is not sufficiently supplied to the tips of the stirring blades. For this reason, the improving agent may not be uniformly distributed in the soil, which may cause unevenness in the soil quality. Also, the shape of the stirring blade is a flat plate provided at right angles to the axis,
Alternatively, since the blades are only slightly inclined inward and outward, the stirring blade cuts the same plane in the soil during rotation, which may result in insufficient stirring.

The present invention has been made by paying attention to the above problems, and it is possible to uniformly inject the improver into the soil and sufficiently stir the mixture to obtain improved soil having no unevenness and good quality. The purpose is to provide a stirrer.

[0010]

[Means for Solving the Problems, Actions and Effects] In order to achieve the above-mentioned object, the first invention is to supply an improving agent into the ground which has been drilled, and to mix and mix the soil and the improving agent. In a drilling stirrer for improving soil quality, the drilling stirrer comprises:
It is composed of a tubular outer shaft that is rotationally driven separately and an inner shaft that is inserted into the outer shaft with a gap, and an outer shaft improving agent supply passage and an inner shaft improving agent supply passage are provided in each of the outer shaft and the inner shaft. A double tube shaft, a plurality of stirring blades provided on the outer side of the outer shaft, a drilling blade provided on the tip of the inner shaft, and a plurality of stirring blades provided on the respective stirring blades. It is configured to have a first improving agent discharge port.

According to the first aspect of the present invention, since the plurality of first improving agent discharge ports are provided on the stirring blade provided on the outer side of the outer shaft of the double tube shaft, the soil around the rotating stirring blade is surely secured. The improver can be injected and stirred and mixed. Therefore, the improving agent can be uniformly distributed over the entire area of the drilled hole, and improved soil of good quality can be obtained.

A second aspect of the present invention is a drilling stirrer for supplying an improving agent into the ground to which the hole has been drilled, and stirring and mixing the soil and the improving agent to improve the soil quality. A tubular outer shaft that is driven to rotate by an inner shaft and an inner shaft that is inserted into the outer shaft with a gap, and has an outer shaft improving agent supply passage and an inner shaft improving agent supply passage in each of the outer shaft and the inner shaft. A heavy pipe shaft, a plurality of stirring blades provided outside the outer shaft, a boring blade provided at the tip of the inner shaft, and a second improving agent discharge port provided in the boring blade. And is configured to have.

According to the second aspect of the invention, since the second improving agent discharge port is provided in the drilling blade provided at the tip of the inner shaft, the modifying agent can be surely injected into the soil around the rotating drilling blade. Since the improving agent can be injected into the entire area of the hole while drilling and drilling and mixing can be performed, good quality improved soil can be obtained.

A third invention is the first invention according to the first invention.
The improving agent discharge port is opened in a direction opposite to the rotating direction of the stirring blade.

According to the third aspect of the present invention, since the stirring blade rotates in the direction opposite to the opening direction of the first improving agent discharge port, there is no possibility that the first improving agent discharge port will be clogged with soil during rotation in the soil, and it is possible to assure the reliability. The improver can be poured into the soil.

A fourth invention is the first or second invention,
The stirring blade is attached to the first stirring blade extending in the radial direction of the outer shaft, and is attached to the first stirring blade, and is substantially parallel to the rotation direction of the first stirring blade in a plan view and in a side view. The second stirring blade is attached obliquely to the axis of the outer shaft.

According to the fourth invention, the soil is stirred by the first stirring blade extending in the radial direction of the outer shaft and at the same time by the second stirring blade mounted on the first stirring blade. Since the stirring blade is obliquely attached to the outer shaft center in a side view, soil is surely mixed inside and outside in the radial direction of rotation of the stirring blade. Thereby, the soil and the improver can be mixed sufficiently and uniformly.

In a fifth aspect based on the fourth aspect, a plurality of the agitating blades are provided, and the second agitating blades of the respective agitating blades of the respective agitating blades of the respective agitating blades are rotated when the outer shaft makes one revolution. It is arranged so that the drawn loci are different from each other.

According to the fifth invention, when the outer shaft makes one rotation, the trajectories drawn by the respective second stirring blades of the plurality of stirring blades are different from each other, so that the soil is finely sheared by these second stirring blades. Since it is evenly stirred in the vertical direction and the rotating direction, the soil and the improving agent can be uniformly and sufficiently kneaded. Therefore, it is possible to reliably obtain good quality improved soil.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic side view of the hole-stirring device 1 of the first embodiment. In FIG. 1, a support 3 is engaged with a reader 2 so as to be slidable in a vertical direction, and a speed reducer 5 having a hydraulic motor 4 is attached to the support 3. At the bottom of the speed reducer 5, the first swivel joint 1
A double tube shaft 30 having an inner shaft 31 and an outer shaft 40 externally inserted on the inner shaft 31 is attached via the planetary gear speed reducer 20. Inner shaft 3 protruding downward from the outer shaft 40
A drilling blade 33 is provided at the lower end portion of 1. Also,
A second swivel joint 11 is provided at the upper end of the outer shaft 40, and a plurality of stirring blades 42a, 42b, 4 are provided at the lower end.
2c and 42d are provided. Further, a first supply pipe 12 and a second supply pipe 13 are connected to the first swivel joint 10 and the second swivel joint 11, respectively. The improving agent is supplied via the.

FIG. 2 is a partial sectional view showing the construction of the inner shaft and outer shaft driving portions. In FIG. 2, the first swivel joint 10 is fixedly mounted on the support 3, and the output shaft 6 of the speed reducer 5 and the upper end of the inner shaft 31 of the double pipe shaft 30 attached to the first swivel joint 10. Are connected to each other via a first swivel joint 10. A carrier 23 that rotatably supports a planetary gear 22 of the planetary gear speed reducer 20 is fixed to a lower portion of the first swivel joint 10, and the sun gear 21 meshing with the planetary gear 22 is an inner shaft 31. The ring gear 24 is fixed to the outer shaft 40. The first supply pipe 12 is connected via a first swivel joint 10 to an inner shaft improving agent supply passage 32 axially provided in an inner shaft 31. The second supply pipe 13 is an outer shaft improving agent formed between the inner shaft 31 and the outer shaft 40 of the double pipe shaft 30 via the second swivel joint 11 fixed to the lower portion of the support body 3. It is connected to the supply passage 41.

FIG. 3 is a view taken in the direction of arrows AA in FIG. 1, and is a plan view showing the structure of an example of the drilling blade 33. In FIG.
The three bits 34, 34, 34 constituting the boring blade 33 communicate with the inner shaft improving agent supply passage 32 and are radially opened from the inner shaft improving agent supply passage 32 toward the tip end. 2 improver discharge ports 35, 36 are provided. The second improving agent discharge port 35 opens near the tip of the drilling radius R of each bit 34, and the second improving agent discharge port 36 opens at a position approximately half the drilling radius R.

FIG. 4 is a view taken in the direction of arrows BB in FIG. 1, and is a plan view showing the structure of an example stirring blade. In FIG. 4, four stirring blades 42a, 42b, 42c, 42d are fixedly mounted on the outer shaft 40 in directions orthogonal to each other around the axis. The stirring blade 42a is a hollow first stirring blade 43a extending in the radial direction of the outer shaft 40 and a second stirring blade 42a attached to the first stirring blade 43a in a direction perpendicular to the radial direction of the outer shaft 40. And a stirring blade 44a. An improving agent supply hole 45a communicating with the outer shaft improving agent supply passage 41 is provided in the first stirring blade 43a in the longitudinal direction of the stirring blade, and the improving agent supply hole 45a has a first stirring blade indicated by an arrow P in the drawing. A first opening that opens in the horizontal direction opposite to the rotation direction of 43a.
A plurality of improving agent discharge ports 46a are provided from the base end portion to the tip end portion of the first stirring blade 43a. The stirring blade 42b similarly includes a first stirring blade 43b and a second stirring blade 44b, and the first stirring blade 43b is provided with an improving agent supply hole 45b and a first improving agent discharge port 46b. The stirring blade 42c includes a first stirring blade 43c and a second stirring blade 44c, and the first stirring blade 43c is provided with an improving agent supply hole 45c and a first improving agent discharge port 46c. Further, the stirring blade 42d is provided with a first stirring blade 43d and a second stirring blade 44d, and the first stirring blade 43d is provided with an improving agent supply hole 45d and a first improving agent discharge port 46d.

Each second stirring blade 44a, 44b, 4
The width W of 4c and 44d is set to a predetermined dimension that exceeds the outer diameter dimension of the outer shaft 40. In addition, as shown in FIG.
The stirring blades 42a and 42b are provided on the same axis and with a phase difference of 180 degrees in the rotation direction of the outer shaft 40 (that is, facing each other), while the stirring blades 42c and 42d are the stirring blades 42a and 42d. There is a 90-degree phase difference in the rotation direction of the outer shaft 40 with respect to 42b (that is, in the direction perpendicular to it), and the axial centers of the second stirring blades 44a and 44b are substantially aligned with the positions of the lower ends thereof. Are provided so as to face each other. Further, these stirring blades 42a, 42b, 42 are provided below the outer shaft 40.
Two sets are provided side by side in the axial direction, with c and 42d as one set.

FIG. 5 is a view taken along the line CC in FIG. 4, and is a side view showing an example of the configuration of the stirring blades 42a and 42b. The second stirring blade 44a having a rectangular shape is substantially perpendicular to the axis of the first stirring blade 43a fixed to the outer shaft 40 by extending in the radial direction thereof (that is, in a plan view as shown in FIG. 4). ,
It is attached substantially parallel to the rotation direction) and is attached obliquely to the axis line XX of the outer shaft 40. Similarly, the second stirring blade 44b of the stirring blade 42b also has an axis X of the outer shaft 40.
-The second stirring blade 4 is installed obliquely with respect to -X
4a and the 2nd stirring blade 44b incline in the same direction.

FIG. 6 is a view taken in the direction of arrows D--D in FIG. 4, and is a side view showing an example of the configuration of the stirring blade 42c and the stirring blade 42d. A first member fixed to the outer shaft 40 by extending in the radial direction thereof
A rectangular second stirring blade 44c attached to the stirring blade 42c substantially parallel to the rotation direction in plan view shown in FIG.
Is bent at a substantially central portion in the vertical direction, and its upper and lower portions are inclined in opposite directions with respect to the axis X-X of the outer shaft 40 and are formed in a dogleg shape as a whole. Similarly, the second stirring blade 44d of the stirring blade 42d is also formed in a V shape in which the upper portion and the lower portion are inclined in opposite directions with respect to the axis line XX of the outer shaft 40. Then, these second stirring blades 44
The a, 44b, 44c, and 44d are arranged such that the loci drawn by the outer shaft 40 are different from each other when the outer shaft 40 makes one rotation.

Next, the operation will be described. In FIG. 2, when the output shaft 6 is rotationally driven by the hydraulic motor 4 via the speed reducer 5, the sun gear 21 and the inner shaft 31 rotate in the same direction as the output shaft 6. The ring gear 24 and the outer shaft 40
And rotate in the opposite direction via the planetary gear 22.
Therefore, the outer shaft 40 has low rotation and high torque with respect to the inner shaft 31.

In FIGS. 1, 2 and 3, the drilling blades 33 rotate to drill the ground, and the modifying agent supplied from the first supply pipe 12 serves as the modifying agent discharge ports 35, 35 of the bit 34.
36 is discharged into the ground. Since the improving agent discharge ports 35 and 36 are opened at approximately the tip of the bit 34 and at a position approximately half the drilling radius R, the modifying agent is uniformly supplied and agitated by the drilling blade 33.

1, 2, and 4, when the outer shaft 40 rotates, the stirring blades 42a, 42b, 42c, 42d stir the soil cut by the boring blade 33. At the same time, the improving agent supplied from the second supply pipe 13 is the first improving agent discharge port 46.
It is discharged into the ground from a, 46b, 46c and 46d. The first improving agent discharge ports 46a, 46b, 46c, 46d are the first
Since the stirring blades 43a, 43b, 43c, 43d are open at a plurality of locations from the base end portion to the tip end portion, the stirring blades 43a, 43b, 43c, 43d are uniformly supplied over the entire drilling area, stirred and kneaded with the soil.

In FIG. 4, when the outer shaft 40 rotates, the second stirring blades 44a, 44b, 44c, and 44d have a width W, so that the end of the width W of the second stirring blade 44a is the radius. Difference S between arc M and arc N having the radius at the center of width W
The soil in the area of the second stirring blades 44a, 44b,
The entire length of 44c and 44d in the vertical direction is moved in the rotational direction. Therefore, the soil and the improver are sufficiently kneaded.

FIG. 7 shows that when the outer shaft 40 makes one rotation,
The stirring blades 44a, 44b, 44c, and 44d show loci drawn on the same vertical plane. As aforementioned,
The trajectories are located in different places, and the soil is finely sheared. Therefore, the soil is uniformly and sufficiently agitated together with the radial movement of the soil, and the soil and the improver are well kneaded to obtain a good quality improved soil.

FIG. 8 is a view taken in the direction of arrow F in FIG. 5, and is a front view of the second stirring blade of another embodiment. In FIG. 8, a plurality of comb-teeth-shaped slits 47 are provided at both left and right ends of a rectangular second stirring blade 44e forming the second stirring blades 44a, 44b, 44c, and 44d in the previous embodiment. ing.
Since the soil is agitated when moving in the rotating direction due to the presence or absence of the slit 47, the agitation and mixing of the soil can be further improved.

FIG. 9 is a front view of another embodiment of the double hole punching and stirring device 1a. In FIG. 9, the lower part of the speed reducer 5a having one hydraulic motor 4a is provided with two sets of planetary gear speed reducers 20, 20 at the tip end thereof for drilling blades 3.
Two double tube shafts 30 each of which is composed of an inner shaft 31 having the number 3 and an outer shaft 40 having the stirring blades 42a, 42b ... Are provided in parallel. Note that a configuration with two or more stations is also possible.

In the above embodiment, the stirring blades are arranged so that four blades / set are changed in phase so that they are orthogonal to each other in a plan view. For example, six blades / set are set by changing the phase by 60 degrees. The arrangement and the number / set may be performed in other phases, such as arranging or arranging 3 pieces / set by changing the phase by 120 degrees. Further, two sets of four stirring blades are arranged for one double tube shaft, but the number of sets may be arbitrary (one set or more).

Since the hole-stirring agitator of the present invention is constructed as described above, the following effects can be obtained. Since the first improving agent discharge port is provided on the stirring blade provided on the outer side of the outer shaft of the double pipe shaft, the improving agent can be surely injected into the soil around the rotating stirring blade to stir and mix. . In particular, since the plurality of first improving agent discharge ports are provided from the base end portion to the tip end portion of the stirring blade extending in the radial direction of the outer shaft, the improving agent can be injected almost uniformly over the entire area of the drilled area. For this reason,
The improver can be uniformly distributed in the soil, and good quality improved soil can be obtained. Since the second improving agent discharge port is provided on the drilling blade provided at the tip of the inner shaft, the modifying agent can be surely injected into the soil around the rotating drilling blade, and the modifying agent is provided while drilling. Can be drilled and mixed by pouring into the entire hole.
Further, by providing a plurality of second improving agent discharge ports from the base end portion to the tip end portion of the drilling blade, the modifying agent can be uniformly distributed and mixed throughout the drilling area while drilling. Therefore, good quality improved soil can be obtained.

It is possible to reliably supply the improving agent into the soil without fear that the first improving agent discharge port will be clogged with the soil during the rotation of the soil. The stirring blade includes a first stirring blade that extends in the radial direction of the outer shaft and is attached thereto, and a second stirring blade that is attached in a direction perpendicular to this in a plan view and obliquely with respect to the outer shaft center in a side view. Is equipped with. Therefore, the soil is stirred by both the first stirring blade and the second stirring blade, and the second stirring blade surely mixes the soil inside and outside the radial direction of rotation of the stirring blade. Thereby, the soil and the improver can be mixed sufficiently and uniformly.

Since the shape of the plurality of second stirring blades in the side view (refraction shape, inclination angle, etc.) and the mounting positions are made different, the loci drawn by the respective second stirring blades when the outer shaft makes one rotation. Therefore, the soil is finely sheared, and the soil and the improver can be uniformly mixed and kneaded because the soil is finely sheared and is evenly stirred in the vertical and rotational directions. Therefore,
It is possible to reliably obtain good quality improved soil. The inner shaft and the outer shaft are rotationally driven through the planetary gear speed reducer, and the outer shaft is rotated at low speed and high torque through the ring gear of the planetary gear speed reducer. Can be rotated. For this reason, the stirring blade having the first stirring blade and the second stirring blade can be stably driven to rotate, so that the soil can be finely sheared and stirred, and a good quality improved soil can be obtained.

[Brief description of drawings]

FIG. 1 is a side view of a hole agitating device of the present invention.

FIG. 2 is a partial cross-sectional view of an inner shaft and an outer shaft driving portion of a hole agitating device.

FIG. 3 is a plan view of a boring blade.

FIG. 4 is a plan view of a stirring blade.

5 is a view taken along the line CC of FIG.

FIG. 6 is a view on arrow D-D of FIG. 4.

FIG. 7 is a diagram showing a locus drawn by a second stirring blade.

FIG. 8 is a front view of a second stirring blade of another embodiment.

FIG. 9 is a front view of a hole drilling agitator according to another embodiment.

FIG. 10 is a schematic side view of a self-propelled underground hole stirring device.

FIG. 11 is a partial sectional perspective view of an underground mixer of a conventional underground mixer.

FIG. 12 is a schematic side cross-sectional view of a conventional double pipe hole kneading machine.

[Explanation of symbols]

1, 1a ... Hole agitating device, 4, 4a ... Hydraulic motor, 5,
5a ... reducer, 6 ... output shaft, 10 ... first swivel joint, 11 ... second swivel joint, 12 ... first supply pipe, 13 ... second supply pipe, 20 ... planetary gear speed reducer, 21
... Sun gear, 22 ... Planetary gear, 23 ... Carrier, 24 ... Ring gear, 30 ... Double tube shaft, 31 ... Inner shaft,
32 ... Inner shaft improving agent supply passage, 33 ... Drilling blade, 34 ... Bit, 35, 36 ... Second improving agent discharge port, 40 ... Outer shaft, 41
... Outer shaft improving agent supply passage, 42a, 42b, 42c, 42
d ... Stirring blade, 43a, 43b, 43c, 43d ... First stirring blade, 44a, 44b, 44c, 44d, 44e ... Second
Stirring blades, 45a, 45b, 5c, 45d ... Improving agent supply hole, 46a, 46b, 46c, 46d ... First improving agent discharge port, 47 ... Slit.

Claims (5)

[Claims] 1. A drilling stirrer for injecting an improver into a holed ground, stirring and mixing soil and the improver to improve soil quality, in a tubular outer shaft (40) which is rotationally driven. ),
And an inner shaft (31) inserted with a gap in the outer shaft (40), and the outer shaft (40) and the inner shaft (31) each have an outer shaft improving agent supply passage in the axial direction. (41) and a double pipe shaft (30) having an inner shaft improving agent supply passage (32), a stirring blade (42a) provided on the outer side of the outer shaft (40), and the inner shaft (31) A hole drilling and stirring device comprising: a hole drilling blade (33) provided at the tip end of the hole; and a first improving agent discharge port (46a) provided in the stirring blade (42a). 2. A drilling stirrer for injecting an improver into a holed ground and stirring and mixing soil and the improver to improve soil quality, in a tubular outer shaft (40) which is rotationally driven. ),
And an inner shaft (31) inserted with a gap in the outer shaft (40), and the outer shaft (40) and the inner shaft (31) each have an outer shaft improving agent supply passage in the axial direction. (41) and a double pipe shaft (30) having an inner shaft improving agent supply passage (32), a stirring blade (42a) provided on the outer side of the outer shaft (40), and the inner shaft (31) A hole drilling agitator having a hole drilling blade (33) provided at the tip of the hole and a second improving agent discharge port (35) provided in the hole drilling blade (33). 3. The hole-stirring device according to claim 1, wherein the first improving agent discharge port (46a) is opened in a direction opposite to a rotation direction of the stirring blade (42a). . 4. The hole-stirring device according to claim 1 or 2, wherein the stirring blade (42a) is provided with a first stirring blade (43a) extending in the radial direction of the outer shaft (40). The first stirring blade
A second stirring blade (44a) attached to (43a) and substantially parallel to the rotation direction of the first stirring blade (43a) in a plan view, and obliquely attached to the axis of the outer shaft (40) in a side view. ) And a hole-stirring stirring device. 5. The hole-stirring device according to claim 4,
A plurality of the stirring blades (42a), each stirring blade (42a)
The second stirring blades (44a) are arranged such that the loci drawn by the respective second stirring blades (44a) are different from each other when the outer shaft (40) makes one revolution. Hole stirrer.