JPS63284311A - Soil hardening improver and stirring blade for soft clayey ground - Google Patents

Abstract

PURPOSE:To uniformly mix soft ground with a hardener by providing a rotary blade turning around the horizontal shaft for a stirrer to mix soil with a soil hardener liquid. CONSTITUTION:A stirrer is provided for the upper part of an excavator 51, e.g., auger, to excavate soft clayey ground, and the shaft 51 constituting the stirrer 5 is provided with a number of horizontally provided rotary shafts 53 and rotary shafts 52 made up of cross-shaped blades 54 from view of the end of the shaft 53. A chain 100 set in the wall of the shaft 51 is engaged with bevel gears 200, 240, and 260, the bevel gear 240 is connected to the shaft 53, and the blade 52 is forcibly turned.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a ground improvement device for soft clay layers, and in particular, the present invention relates to a soil improvement device for soft clay layers, and in particular, a soft clay layer that is optimal for injecting a cement-based hardening material into soft soil and uniformly mixing the hardening material and soft soil. The present invention relates to a soil hardening improvement device for a clay layer and a stirring blade.

[Conventional technology]

In the construction of a modern social state, there are various construction location conditions, and these various construction location conditions must be overcome. In recent years, it has become increasingly common for high-rise buildings to be constructed on soft ground that is not suitable for construction site conditions for high-rise buildings. Unless high-rise buildings are constructed on soft ground that is not suitable for such construction site conditions, it is not possible to make effective use of the limited national land. Conventionally, in response to such problems, replacement construction methods, sand drain construction methods, compacted sand pile construction methods, etc. are well known. However, recently, due to environmental conservation and pollution prevention considerations, it has become difficult to excavate trenches, treat soft soil, and collect high-quality sand, making it impossible to use conventional methods. Therefore, in recent years, efforts have been made to develop soft ground improvement methods using cement. This involves injecting a cement-based hardening material into the soft ground, forcing the hardening material and the top of the soft ground to mix by rotating a blade horizontally, and using the hardening reaction to strengthen the soft soil itself. The aim is to That is,
Soft soil and cement milk are forcibly stirred and mixed mechanically by rotating blades laterally, liquefied once, and solidified by the chemical reaction of the cement to create strong panels. For this forced stirring, a stirrer as shown in FIG. 20 is used. That is, the shaft 1000, on which the rotational drive device is installed at the upper end, is provided with a set of three blades 1020 extending in the radial direction from the center line of the shaft 1000 in four stages with an opening of 120 degrees. A perforating member 1030 such as an auger is provided at the tip of this shaft 1000. Also, shaft 100
A guide member 1040 is attached to the guide pile 1050 so as to fall straight down along the outer surface of the guide pile 1050. By rotating this shaft 1010 in the direction shown by arrow A in FIG. 20, the blades 1020 rotate in the same direction as the shaft 10010 and stir while drilling. The improvement of soft soil using this agitator is carried out by the method shown in FIG. 21. That is, first, in FIG. 21 (A), set the stirring shaft 1010 at the stirring point of the improved softness ±2000,
Stirring and settling are started, and as shown in FIG. 21(B), hardening liquid (cement milk) is injected while stirring and settling. Next, as shown in FIG. 21(C), when the material is stirred and deposited to the designed depth, the agitator is pulled up as shown in FIG. 21(D). It is also possible to inject the cement milk when the stirrer is pulled up. Then, as shown in FIG. 21(E), the process ends when the agitator is lifted up to the ground surface.

[Problems to be solved by the invention]

In the conventional construction method of injecting cement milk while stirring, the cement milk is poured into the shaft 1010 while drilling a soft hole of ±2000 mm with the perforating member 1030.
It is poured out from inside and stirred with a blade 1020. However, in such conventional stirring, the stirring blade 1020 only rotates laterally in the same direction as the shaft 1010, as shown by arrow B in FIG. Therefore, the cement milk poured out from inside the shaft 1010 is not sufficiently mixed with the soil and gravel softened by the perforating member 1030 and the blades 1020, and as shown in FIG. 3000 gravel and 400 concrete blocks
There is a problem that 0 and 0 are layered or formed as a plurality of blocks. For this reason, using conventional methods, soft soil cannot be improved sufficiently.
The problem is that soft soil cannot be improved to hard soil. ,

[Means to solve the problem]

The first invention of the present application is capable of injecting a cement-based hardening material into soft ground to uniformly mix the hardening material and the soft soil, and includes an excavation part having digging teeth that excavates by rotating; The excavator is equipped with a ball that presses and settles the excavation part, and a means for injecting a soil hardening liquid into the excavated earth and gravel through the pole, and the excavation part is rotated to break down the earth and gravel while digging. The above-mentioned high-quality hardening liquid is injected into the crushed earth and gravel by pressure, and the above-mentioned pole and the above-mentioned excavation part are provided with a mechanism that rotates in synchronization, and the above-mentioned pole is provided with a rotary blade that rotates back and forth in the excavation direction. be. The second invention of the present application is capable of injecting a cement-based hardening material into soft ground and uniformly mixing the hardening material and soft soil. In this device, a rotor blade having one or more blades is rotatably provided on a shaft that can be detachably connected to the pole, and is provided with one or more blades at appropriate locations on the circumferential surface of the rotating shaft. The third invention of the present application is capable of injecting a cement-based hardening material into soft ground to uniformly mix the hardening material and the soft soil, and includes a shaft whose one end is configured to be detachably attached to a drive member; The rotary blade is configured such that a groove is wound spirally around the shaft at a predetermined distance, and a rotary blade is rotatably suspended between the shaft and the groove.

【Example】

Examples of the present invention will be described below. FIG. 1 shows a first embodiment of the first invention of the present application. In the figure, a soil hardening improvement device 1 for a soft clay layer is configured to be supported and guided by a leader 2. The soil hardening improvement device 1 for a soft clay layer is composed of a driving section 3, a pole 4, an agitating section 5, and an excavating section 6. 7 is a slide steady rest. The drive section 3 descends downward along the leader 2, and has the effect of suppressing the pole 4 downward. The pole 4 is detachably fixed to the drive section 3, and the stirring section 5 is fixed to the lower end of the pole 4. A drilling part 6 such as an auger is rotatably fixed to the lower end of the stirring part 5. The stirring section 5 has a configuration as shown in FIG. Second
The figure shows the agitator digging into excavated earth and sand A91 of soft soil 9. In the figure, a shaft 51 constituting the agitating section 5 is provided with a plurality of rotary blades 52 rotatably arranged on the same stage (in FIG. 2, two rotary blades 52 are located at opposing positions). Further, the rotary blades 52 are provided in multiple stages (five stages in FIG. 2). The rotary blade 52 is composed of a rotating shaft 53 and blades 54. The blades 54 are provided at four locations on the rotating shaft 53 in a cross shape when viewed from the end surface of the shaft, and three blades are provided in the longitudinal direction of the rotating shaft 53. A predetermined interval is provided between these three blades 54. Further, holes 55 and 56 are provided at the lower part of the shaft 51 for pouring soil hardening liquid (cement milk) into the earth and gravel 91. The number and diameter of the holes 55 and 56 vary depending on the depth and size of the holes. Further, at the lower end of this shaft 51, an excavation part 6 is rotatably provided via a joint 8. This excavation part 6
is composed of a rotating shaft 61 and a spiral tooth 62 provided on the shaft 61. Each of the rotary blades 52 is configured to be forcibly rotated by a drive mechanism as shown in FIG. That is, a shaft 51 of the stirring section 5 is fixed to the pole 4 via a joint 9. This pole 4
A chain 100 is configured to be able to run within the wall. One end of this chain 100 is suspended from a gear 230 of a rotating shaft 210 of a bevel gear 200. Further, the other end of the chain 100 is suspended by a rotational drive device (not shown) provided within the drive section 3. Further, the rotating shaft 210 of this bevel gear 200 is rotatably provided on the outer wall 280 of the shaft 51 via a bearing 220. This bevel gear 200 is screwed with a bevel gear 240. This bevel gear 24
0, a rotating shaft 53 of a rotary blade 52 is fixed. This rotating shaft 53 is provided to penetrate the outer wall 280 and is supported by a bearing 250. Further, a bevel gear 260 is screwed into this bevel gear 240, and this bevel gear 260 is supported by a rotating shaft 270 on the outer wall. Furthermore, another bevel gear is threadedly engaged with this bevel gear 260, and by threading the bevel gears one after another in this way, the rotary blades 52 on the same plane can be rotated by the drive of the chain 100. A plurality of chains 100 are provided, and all the rotary blades can rotate at the same time. Therefore, according to this embodiment, stirring and mixing is performed as shown by arrow C1D in FIG. As shown in Figure (B), the cement milk mixed earth and gravel 92 is uniformly mixed over the entire length of the hole. The agitation back and forth in the excavation direction as shown by arrows C and D in FIG. 4(A) may be a simple back and forth movement rather than rotational agitation in the fore and aft direction. Also, Figure 4 (A)
In this case, the stirring directions (arrows C and D) are the same, but the left and right directions may be different, and the stirring direction may be reversed before and after excavation (up and down in FIG. 3(A)). in this case,
This can be easily achieved by using one more bevel gear to rotate the rotor blade 52. FIG. 5 shows a second embodiment of the first invention of the present application. This embodiment is provided with a cylindrical body 57 that surrounds the rotor blade 52 of the embodiment shown in FIG. 1 from the outside. This cylinder 5
One end of a rotating shaft 53 of each rotary blade 52 is rotatably provided on the inner wall of the rotary blade 7 . That is, the cylindrical body 57 is supported by the rotating shaft 53 of each rotary blade 52. Therefore, according to this embodiment, the cylinder body 57 can absorb the vibration that occurs when the rotary blade 52 rotates. Further, according to this embodiment, since the earth, gravel and cement milk are stirred and mixed within the cylinder 57, the agitated material does not escape to the outside, and the soil can be uniformly hardened in a columnar shape. A third embodiment of the first invention of the present application is shown in No. 5 (21). 310 is fixed to this joint 310.
A through hole 315 having the same inner diameter as the through hole 315 is provided, and a cylindrical inner shaft 320 having the same inner diameter as the through hole 315 is fixed to the joint 310. A joint 350 is fixed to the lower end of this inner shaft 320. This joint 350 has an excavation section 50.
0 is fixed. Moreover, the surface of this joint 310 on the excavation part 500 side,
Bevel gears 370 and 380 are formed on each of the surfaces of the joint 330 on the ball 300 side along the outer peripheral surface of the inner shaft. Further, on the outside of this inner shaft 320, a cylindrical outer shaft 340 is arranged at a predetermined distance from the inner shaft 320, and a bearing 3 is connected to the joint 310 side.
50 is rotatably provided on the joint 330 side by a bearing 360. This inner shaft 320
A bevel gear 410 is provided in the gap between the outer shaft 340 and the outer shaft 340 so as to be screwed into the bevel gear 370 . This bevel gear 410 is connected to a bearing 412 by a rotating shaft 412.
It is pivotally supported by the outer shaft 340 via the outer shaft 340 . A bevel gear 420 is provided to be screwed onto this bevel gear 410. A rotating shaft 425 of the rotary blade 400 is fixed to this bevel gear 420 . In this way, the combination of bevel gears enables interlocking with all rotary blades. Similarly, a bevel gear 440 is screwed to the bevel gear 380, and this bevel gear 440 is connected to the rotating shaft 44.
2 through the outer shaft 34 through the bearing 444.
It is pivoted at 0. A bevel gear 450 fixed to a rotating shaft 455 of the rotor blade is screwed into this bevel gear 440 . A bevel gear 460 is fixed to this bevel gear 450, and all bevel gears are connected to a bevel gear 370 of the joint 310 and a bevel gear 380 of the joint 330. Therefore, when the ball 300 rotates in the direction shown by the arrow F, the joint 310 . Joint 3 via inner shaft 320
30 rotates in the direction shown by arrow G. Then, the bevel gear 410 screwed into the bevel gear of the joint 310,
500 rotate in the directions shown by arrows H and J, respectively. On the other hand, bevel gears 440 and 600 screwed into bevel gear 380 of joint 330 rotate in the directions shown by arrows K and -, respectively. Therefore, when the ball 300 rotates, the rotor blade 400 moves toward the pole 30 due to the resistance of the gravel.
In addition to moving in the same direction as 0, each rotor blade 400 also rotates in the longitudinal direction of the shaft due to the action of the bevel gear. Therefore, according to this embodiment, a drive source for rotating the rotary blade 400 in the longitudinal direction of the shaft is not required. FIG. 7 shows a first embodiment of the second invention of the present application. In the figure, the stirring R700 is connected to a shaft 720 fixed to a drive shaft (not shown) via a joint 710.
A rotary blade 730 rotatably fixed to this shaft 720, and a cylindrical body 7 that encloses this rotary blade 730.
40. A plurality of rotary blades 730 are rotatably provided at one end of the shaft 720 . The other end of the rotary blade 730 is rotatably attached to the inner wall of the cylindrical body 740. This cylindrical body 740 is connected to the rotor blade 73
0 is fitted inside. The rotary blade 730 is attached to the shaft 720 and the cylinder body 740 in the eighth
It is configured as shown in the figure. i.e. 73 to rotation 5
0 is provided with bearings 750, 760 at both ends thereof, and a shaft 770 is attached to these bearings 750, 760.
is fitted. This shaft 770 is fixed to the shaft 720 and the cylindrical body 740. Therefore, rotor blade 7
30 is supported by a shaft 770 via bearings 750 and 760, and is configured to rotate freely around this shaft 770. As described above, in this embodiment, the rotor blade 730 is free to rotate. Other embodiments of the rotor blade 730 are shown in FIGS. 9-11. The rotor blade 810 shown in FIG. 9 is formed into a triangular prism shape. 815 is a bearing. Further, the rotor blade 820 shown in FIG. 10 has four plate-shaped blades arranged in a cross shape when viewed from the shaft end surface. 825 is a bearing. The rotary blade 830 shown in FIG. 11 has a plurality of blades 832 curved with respect to the rotating direction attached to a rotating shaft 834, and 836 is a bearing. 12 shows a first embodiment of the second invention of the present application. That is, rotary bearings 780 and 790 are provided on the outer wall of the shaft 720 and the inner wall of the cylindrical body 740, and both ends of the shaft 770 of the rotation ff730 are rotatably fitted in the rotary bearings 780 and 790. An embodiment of the rotor blade used in FIG. 12 is shown in FIG. 13. That is, the rotation g840 is constructed by attaching three plate-shaped blades to a shaft 842, and the difference from the rotary blade shown in FIGS. 9 to 11 is that the rotary blade shown in FIGS. The point is that the rotor itself is equipped with a bearing. In this way, even if the rotor blades can rotate freely. By rotating the shaft 52, the shaft 52 rotates due to the resistance between the earth and gravel and the cement milk, and can perform appropriate agitation and mixing. FIG. 14 shows that the shaft of the stirring section 5 is changed from a cylindrical shaft to a rectangular tube shape. A soil hardening material (cement milk) is attached to the lower end of this rectangular cylindrical shaft 900.
A hole 910 is provided for injecting. It is more effective to provide the holes 910 at different heights on each of the four sides. FIG. 15 shows a first embodiment of the third invention of the present application. In the figure, the stirring teeth 600 are Shirt I・610,
It is composed of hollow teeth 620 and 625 and a rotary blade 630. A joint 611 connected to a rotational drive member (not shown) is fixed to one end of the shaft 610. Usually, it is jointed to the tip of the ball 4 shown in FIG. Further, the other end of this shaft 610 is configured to be able to discharge soil hardening liquid (cement milk) 640. This soil hardening liquid (cement milk) 640 is guided inside the shaft 610 via a pole or the like connected to the joint 611 of the shaft 610, and the inside of the shaft 610 is hollow. Further, around this shaft 610, there are band-shaped groove teeth 620 and groove teeth 6.
25 are spirally wound around the shaft 610 at a predetermined distance with a phase difference of 180°. The groove teeth 620 and the groove teeth 625 are as shown in FIG.
It is fixed to the shaft 610 by a fixed shaft 631 that supports rotation g6ao. A plurality of fixed shafts 631 are attached in a direction perpendicular to the central axis of the shaft 610. A cylindrical rotating shaft 632 is fitted into the fixed shaft 631, and a bearing 633 is fixed to an end of the rotating shaft 632. This bearing 633 allows the rotating shaft 632 to
It is configured so that the peripheral surface of the fixed shaft can be rotated. This rotating shaft 632 is provided with two blades 634 and 635. The rotation of the blades 634 and 635 stirs and mixes the soft earth and gravel dug down by the digging teeth 620 and the cement milk. This rotor blade 630
As is clear from Fig. 5, they are installed at every 45° between each groove. The rotary blades 630 do not necessarily need to be provided every 45° as shown in this embodiment, but are provided at 3° intervals.
It can be provided at any angle within the range of ~1800, and in this case the number of rotary blades may be greater or less. Further, the location of the rotary blades and the number thereof can be changed as appropriate depending on the properties of the soft soil, such as the stickiness of the soft soil. In this way, all the rotary blades 630 are configured to be rotatable in both directions, as shown by the arrow F in FIG. 15. Further, when digging, the shaft 610 is rotated in the direction shown by arrow H in FIG. 15. Therefore, according to this embodiment, the rotary blades can stir the soft soil while digging it up with the digging teeth 620 and 625. Further, the blades 635 of the rotary blade 630 are not limited to a two-blade rotary blade, but may be a rotary blade as shown in FIG. 17. That is, FIG. 17(A) shows a rotary blade 650 provided in a triangular shape. 65 in the diagram
5 is a bearing. Also, in FIG. 17(B),
A rotary blade 660 is shown in which four plate-shaped blades are arranged in a cross shape when viewed from the shaft end surface. In the figure, 665 is a bearing. Further, FIG. 17(C) shows a rotary blade 670 in which a plurality of blades 674 curved with respect to the rotational direction are attached to a rotating shaft 676, and 672 is a bearing. In addition, in FIG. 17(D), a plate-shaped blade 6 is attached to the rotating shaft 682.
A rotor blade 680 is shown in which the rotor blade 84 is provided in a trident shape at 120° when viewed from the end face of the three-bladed shaft. In the figure, 686 is a bearing. Further, FIG. 17(E) shows another embodiment of the rotor blade of the third invention of the present application. The rotary blade 950 according to this embodiment has auger-shaped blades 954 and 956 provided on a hollow rotating shaft 952. Although the soil is soft, it is not only completely clayey, but is also soft enough to be unsuitable for construction, but it can also be quite resistant to agitation. In such a case, by using an auger-shaped rotary blade as in this embodiment, it becomes possible to further dig up and stir the gravel that has been dug up by the digging teeth. Note that 958 in the figure is a bearing. FIG. 18 shows a second embodiment of the third invention of the present application. This embodiment differs from the first embodiment shown in FIG. A tooth 691 facing the same direction is formed at the point where a tooth 690 is provided on the outside.
692, and these teeth 691 and 692 are connected and fixed by a fixing member 693, respectively. Further, the teeth 691 and 692 are fixed to the tip of the shaft 610, facing each other. Therefore, according to this embodiment, the lower part of the shaft 610 can be easily dug down, and stirring can be performed more smoothly. FIG. 19 shows a third embodiment of the third invention of the present application. This embodiment differs from the second embodiment shown in FIG. 18 in that the lower end portions of the excavating teeth 6010 and 6020 are formed into an auger shape. That is, the lower end of the digging tooth 6010 is shaped like an auger, and from the middle, it becomes a band-shaped digging tooth 6010, and there is a predetermined interval between the band-shaped digging tooth 6010 and the shaft 610. A plurality of rotary blades 630 are provided at this interval. It goes without saying that all of the rotor blades shown in FIGS. 17(A) to (E) can be used as the rotor blades used in this embodiment. Therefore, according to this embodiment, soft soil can be sufficiently dug down. In addition, although the rotating blade of the stirring blade having the digging teeth described in the third invention of the present application is free to rotate in each embodiment, it can be similarly carried out with the same configuration as the second invention of the present application. .

【Effect of the invention】

As explained above, according to the first invention of the present application, since the soil is stirred back and forth in the excavation direction without being excavated, and at the same time it is stirred in a direction having a predetermined angle with respect to the excavation direction, Layers of gravel and cement milk,
The sand and gravel and the cement milk do not form blocks on their own, and the sand and gravel and the cement milk can be mixed uniformly. In addition, according to the second invention of the present application, it is possible to easily stir soil that is so soft that it does not have an excavated part at the tip by simply attaching it to a device that rotates and descends. However, since it is stirred in a direction with a predetermined angle, when cement milk is mixed into the soil and gravel as in the past, the soil and gravel that has been dug up and the cement milk may form a layer, or the soil and gravel and the cement milk may be separated from each other. Earth and gravel and cement milk can be mixed uniformly without forming blocks. Further, according to the third aspect of the present invention, since the rotary blade is incorporated in the excavation part, the soft soil excavated and crushed can be immediately mixed with the cement milk discharged from the tip of the shaft. For this reason, as the excavation progresses, it is stirred back and forth in the excavation direction, and at the same time it is stirred in a direction that has a predetermined angle to the excavation direction. and cement milk do not form blocks on their own,
It is possible to uniformly mix gravel and cement milk. Furthermore, according to the third invention of the present application, since it can be used alone as an agitator, even if it is used only for stirring soft soil, it can be easily moved by simply attaching it to the tip of a device that rotates and descends. By stirring back and forth in the direction and at the same time stirring in a direction with a predetermined angle to the direction of travel, the soil and gravel that was dug up and the cement milk are layered when mixing cement milk into the soil and gravel, unlike conventional methods. The sand and gravel and the cement milk can be mixed uniformly without causing the sand and gravel and the cement milk to form blocks on their own.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram showing a first embodiment of the first invention of the present application, Fig. 2 is an enlarged front view of the stirring section of the embodiment shown in Fig. 1, and Fig. 3 is a drive of the rotor blade shown in Fig. 2. A partial cross-sectional view showing the mechanism,
Fig. 4 is a diagram for explaining the details of the first invention of the present application, Fig. 5 is an enlarged partial cross-sectional front view showing a second embodiment of the first invention of the present application, and Fig. 6 is a diagram for explaining the first invention of the present application. FIG. 7 is a partially sectional enlarged front view showing the first embodiment of the second invention of the present application, and FIG. 8 is a partially sectional front view showing the third embodiment of the present invention. 9 to 11 are perspective views showing an embodiment of the rotor blade, FIG. 12 is a partially enlarged sectional view showing a second embodiment of the second invention of the present application, and FIG. 13 is a diagram showing the embodiment shown in FIG. FIG. 14 is a perspective view showing the third embodiment of the second invention of the present application, FIG. 15 is an overall perspective view showing the first embodiment of the third invention of the present application, and FIG. 16 is a perspective view of the rotor blade used. Fig. 15 is a partial cross-sectional view of the stirring tooth showing the attachment state of the illustrated rotor blade and the device; Fig. 17 (A) to (
E) is a perspective view showing an embodiment of the rotary blade, FIG. 18 is an overall perspective view showing a second embodiment of the third invention of the present application, FIG. 19 is a perspective view showing a conventional agitator, and FIG. FIG. 21, which is a diagram showing the procedure of the ground improvement method, is a diagram for explaining problems caused by the conventional construction method.

Claims (15)

[Claims] (1) An excavation part having digging teeth that excavates by rotating, a pole that presses and settles the excavation part, and a means for injecting a soil hardening liquid into the excavated earth and gravel through the pole, The soil hardening liquid is injected into the soil and gravel by rotating the excavation section and digging while the soil hardening liquid is dug into the excavation section, wherein a mechanism for rotating the pole and the excavation section in synchronization is provided; , a soil hardening improvement device for a soft clay layer, characterized in that the pole is provided with a rotary blade that rotates back and forth in the excavation direction. (2) A soil hardening improvement device for a soft clay layer, as set forth in claim 1 of the patent register, characterized in that a plurality of the rotary blades are provided. (3) A soil hardening improvement device for a soft clay layer, as set forth in claim 1 or 2 of the patent register, wherein the rotor blade is rotated by forced rotation means. (4) The soil hardening of the soft clay layer as set forth in claim 2 or 3 of the patent record, wherein the rotating directions of the rotary blades adjacent to each other before and after the excavation direction are opposite directions. Improved equipment. (5) Claims 1, 2, 3, and 4 of the patent record
In the item described in any one of the paragraphs, the rotor blade is
A soil hardening improvement device for a soft clay layer characterized by being formed into a triangular prism shape. (6) Claims 1, 2, 3, and 4 of the patent record
In the item described in any one of the paragraphs, the rotor blade is
A soil hardening improvement device for a soft clay layer, characterized in that blades formed in a plate shape are installed in a radial direction from the central axis of a rotating shaft. (7) The invention described in claim 6 of the patent record, characterized in that the blade of the rotary blade is divided into several pieces, and a predetermined interval is provided between each of the divided blades. A soil hardening improvement device for soft clay layers. (8) In a device that is connected to a pole equipped with a descending means to agitate the soil and gravel, a shaft that can be detachably connected to the pole is provided with one or more blades at appropriate locations on the circumferential surface of the rotating shaft. A stirring blade characterized in that a rotary blade is rotatably provided. (9) The stirring blade according to claim 8 of the Patent Register, characterized in that the rotary blade is rotated by rotational drive means. (10) The stirring blade according to claim 8 or 9 of the Patent Register, wherein the rotary blade is formed into a triangular prism shape. (11) In the product described in Claim 8 or 9 of the Patent Register, the rotary blade is provided with plate-shaped blades erected in a radial direction from the central axis of the rotating shaft. A stirring blade featuring (12) In the device described in claim 8 or 9 of the patent register, the blade of the rotor is divided into several parts, and a predetermined interval is provided between each of the divided blades. A stirring blade characterized by: (13) A shaft whose one end is configured to be detachably attached to a drive member, a grooved tooth wound around the shaft in a spiral manner while being separated from the shaft by a predetermined distance, and a rotor blade rotatably provided between the shaft and the grooved tooth. An agitation tooth characterized by being configured in a suspended manner. (14) The stirring tooth according to claim 13 of the patent record, characterized in that the lower end of the tooth is formed into an auger shape. (15) The stirring tooth according to claim 13 or 14 of the patent register, wherein the shaft is provided with a tip tooth at its tip.