JP7779534B2 - Crushed stone pile forming attachment and crushed stone pile forming device equipped with the same - Google Patents

Description

The technology disclosed in this specification relates to an attachment for forming crushed stone piles and a crushed stone pile forming device equipped with the attachment.

A method of forming crushed stone piles underground is used for ground improvement, such as countering liquefaction. One method of forming crushed stone piles underground is to use an attachment that is inserted into the ground to create a space. This type of attachment includes a cylindrical portion with a crushed stone insertion hole formed on its side, and a shaft that is rotatably positioned within the cylindrical portion. The upper end of the shaft is connected to the output shaft of the drive unit by a hollow joint rod. Therefore, when the drive unit is driven, its rotational force is transmitted to the shaft via the joint rod, causing the shaft to rotate. The shaft is then rotated in the forward direction to insert the attachment and create a space in the ground. Once the attachment is inserted into the ground, crushed stone is introduced into the internal space of the cylindrical portion, and the attachment is removed by rotating the shaft in the reverse direction to form the crushed stone pile. For example, Patent Document 1 discloses an example of an attachment for forming crushed stone piles.

JP 2010-248885 A

This type of attachment is equipped with a one-way clutch mechanism at the upper end of the cylindrical portion. The one-way clutch mechanism rotates the cylindrical portion when the shaft is rotated in the forward direction, and stops the cylindrical portion from rotating when the shaft is rotated in the reverse direction. A bearing portion is provided immediately above the one-way clutch mechanism, and this bearing rotatably supports the joint rod at a position halfway between the upper and lower ends. Large forces act on the shaft during underground excavation or the formation of crushed stone pillars, and these forces are transmitted to the joint rod. Because the joint rod's movement in directions perpendicular to the axis is restricted by the bearing portion, stress is likely to concentrate at the point where the joint rod is supported by the bearing portion, creating the possibility that the joint rod may break near that point. If the joint rod were to break, the connected drive unit and cylindrical portion would separate, potentially causing the cylindrical portion to fall off the drive unit.

This specification discloses technology that can prevent the cylindrical portion from falling off the drive unit even if the connection between the output shaft of the drive unit and the shaft inside the crushed stone pile formation attachment breaks.

The attachment disclosed in this specification is a crushed stone pile forming attachment that is attached to a crushed stone pile forming device that forms a crushed stone pile in a space formed underground. It is inserted into the ground to form a space, and rises from the ground to form a crushed stone pile in the space. This attachment comprises a cylindrical portion with a crushed stone injection port formed on its side, a shaft that is rotatably arranged within the cylindrical portion and rotates by driving force from a drive unit, a hollow joint rod having a first end and a second end, the first end connected to the output shaft of the drive unit and the second end connected to the shaft, and a core member that is arranged within the joint rod and whose upper end engages with the first end of the joint rod and whose lower end engages with the second end of the joint rod.

In the above attachment, even if the joint rod connecting the output shaft of the drive unit and the shaft breaks midway, the core material housed inside it will lock onto the first end and second end, respectively. This makes it easier to maintain the connection between the output shaft and the shaft, preventing the cylindrical portion from falling off the drive unit.

This specification also discloses a crushed stone pile forming device equipped with the above-mentioned attachment. That is, the crushed stone pile forming device disclosed in this specification includes the above-mentioned attachment and a drive unit that generates rotational driving forces in the forward and reverse directions to drive the attachment. With this crushed stone pile forming device, even if the connecting portion (joint shaft) between the output shaft of the drive unit and the shaft inside the attachment breaks, it is possible to prevent the cylindrical portion from falling off the drive unit.

1 is a diagram showing a schematic configuration of a crushed stone pile forming device according to a first embodiment. FIG. 2 is a view of only the attachment shown in FIG. 1 viewed from a different angle. FIG. 4 is a vertical cross-sectional view showing a connecting portion between the drive device and the cylindrical portion. 1A is a longitudinal cross-sectional view showing a joint rod, and FIG. 1B is a side view of a core material constituting the joint rod. FIG. 10 is a partial vertical cross-sectional view showing a main part of a joint rod according to another embodiment. FIG. 10 is a partial vertical cross-sectional view showing a main part of a joint rod according to another embodiment. FIG. 10 is a side view of the crushed stone pile forming device when transporting the soil improvement machine with the attachment attached.

(Feature 1) In the attachment disclosed in this specification, the joint rod may include a cylindrical main body having a first opening on the first end side and a second opening on the second end side, a first end member joined to the first opening of the cylindrical main body, and a second end member joined to the second opening of the cylindrical main body. With this configuration, the upper end of the core material housed inside the cylindrical main body can be joined to the first end member on the first opening side, and the lower end can be joined to the second end member on the second opening side. This allows the first end member and the second end member to be maintained in a connected state by the core material.

(Feature 2) In the attachment disclosed herein, the upper end of the core material may be welded to the first end member while being inserted through a first central hole in the first end member. This configuration allows the upper end of the core material to be firmly fixed to the first end member.

(Feature 3) In the attachment disclosed in this specification, the lower end of the core material may be fitted into a second central hole in the second end member. The second end member side of the joint rod is disposed inside the cylindrical portion. With this configuration, the lower end of the core material is fixed to the second end member without welding. Furthermore, even if the lower end of the core material is located in a location where welding is difficult, the lower end of the core material can be fixed to the second end member relatively easily.

(Feature 4) In the attachment disclosed herein, a support recess may be formed at the upper end opening of a first central hole in the first end member, a first enlarged diameter portion with a diameter larger than the first central hole may be formed at the upper end of the core member, and the first enlarged diameter portion may be supported by the support recess. With this configuration, even if a force is applied to the core member toward the second end member, the first enlarged diameter portion will not pass through the first central hole but will abut against the support recess and be supported. Therefore, even if the upper end of the core member is not fixed to the first end member by welding or the like, the upper end of the core member will be held without slipping out of the first end member.

(Feature 5) In the attachment disclosed in this specification, an expanded diameter space may be formed at the lower end opening of the second central hole of the second end member, and a second expanded diameter section with a larger diameter than the second central hole may be formed at the lower end of the core member, with the second expanded diameter section being disposed within the expanded diameter space. With this configuration, even if a force is applied to the core member toward the first end member, the second expanded diameter section will not pass through the second central hole but will remain and be supported within the expanded diameter space. Therefore, even if the lower end of the core member is not fixed to the second end member by welding or the like, the lower end of the core member will be held without slipping out of the second end member.

(Feature 6) The attachment disclosed in this specification may further include a bearing portion provided at one end of the cylindrical portion, and the bearing portion may rotatably support the joint rod at a position intermediate the first end and the second end.

The crushed stone pile forming device 100 according to this embodiment will now be described. As shown in FIG. 1, the crushed stone pile forming device 100 comprises a soil improvement machine 40 as a construction machine, and an attachment 10 attached to the soil improvement machine 40. As shown in FIG. 1, the soil improvement machine 40 comprises a soil improvement machine main body structure 1, a cabin 7 as a driver's seat, crawlers 6 as endless tracks that can move over uneven ground with low ground pressure, and outriggers 5 that suppress shaking of the soil improvement machine 40 during construction.

The ground improvement machine 40 further includes, as components for operating the attachment 10, a drive unit 11 that supplies rotational driving force to the attachment 10 via an output shaft 27, a leader 4 having lifting guide rails 9, a lifting platform 17 that raises and lowers the drive unit 11 and attachment 10 along the lifting guide rails 9, a leader mounting base 2 for supporting the leader 4, a hydraulic cylinder 3 that controls the tilt of the leader 4, and an extension column 8 that is formed integrally with the leader 4 at the lower end of the leader 4.

As shown in Figures 1 and 2, the attachment 10 comprises a cylindrical portion 12 provided with fins 13, a shaft 22 (shown in Figure 3), a joint rod 26, a spiral portion 14, an enclosing frame 30 for preventing the cylindrical portion 12 from vibrating, a hanger stay 18 attached to the lifting platform 17, a top cover case 16, a crushed stone feeding device 32, a support plate 37 supporting the enclosing frame 30, a support arm 39 supporting the crushed stone feeding device 32, and a construction management device 41 for managing the construction status of the attachment 10.

The cylindrical portion 12 has a crushed stone insertion hole 15 formed in the axial direction on its side. The crushed stone insertion hole 15 extends in the axial direction of the cylindrical portion 12 and is closed by an opening/closing door 20 made of elastically deformable rubber or resin.

The crushed stone feeding device 32 includes a hopper section 33 and a chute section 34 disposed below the hopper section 33. The crushed stone feeding hole 15 is closed by the opening/closing door 20 when the attachment 10 is excavating underground. This prevents soil and sand from entering the cylindrical section 12 through the crushed stone feeding hole 15. Furthermore, when crushed stone is to be fed into the cylindrical section 12, the opening/closing door 20 is opened. This allows the crushed stone fed into the crushed stone feeding device 32 to be fed into the cylindrical section 12 through the crushed stone feeding hole 15. Furthermore, because the crushed stone feeding hole 15 is formed as a long hole along the axial direction, the crushed stone can be fed into the cylindrical section 12 without changing the crushed stone feeding position, even when the cylindrical section 12 is raised.

As shown in Figures 1 and 2, the helical portion 14 is located at the tip of the cylindrical portion 12 and is connected to the tip of the shaft 22 (shown in Figure 3) so that they can rotate together. An excavation blade is provided at the tip of the helical portion 14. The excavation blade is formed in a spiral shape with a diameter that increases toward the tip of the helical portion 14. Almost the entire excavation blade is disposed within the cylindrical portion 12, with only a portion of the tip of the excavation blade protruding from the tip of the cylindrical portion 12. A helical fin 13 is provided around the outer periphery of the cylindrical portion 12. The fin 13 has a helical shape that rotates in the same direction as the helix of the helical portion 14 (i.e., the excavation blade). In other words, during excavation, the cylindrical portion 12 and the helical portion 14 rotate in the same direction. As a result, the excavated soil produced by excavation by the helical portion 14 is transported to the ground surface by the fin 13.

As shown in Figure 3, the shaft 22 is a member rotatably arranged along its central axis within the cylindrical portion 12, and is made of a steel pipe with a fixed diameter (approximately 8 cm). Radial stays 24 are provided at multiple locations within the cylindrical portion 12, and bearing tubes 23 are fixed via these radial stays 24. The shaft 22 is supported by being inserted into these bearing tubes 23.

The base end of the shaft 22 is connected to a joint rod 26. The joint rod 26 is positioned with a portion of it protruding from the upper end of the cylindrical portion 12, and is connected to the output shaft 27 of the drive unit 11. The joint rod 26 rotates in response to the rotational driving force of the output shaft 27, and transmits this rotational driving force to the helical portion 14 via the shaft 22, which is integrally connected to the joint rod 26. The detailed configuration of the joint rod 26 will be described later.

The top cover case 16 is attached to the rear end (base end) of the cylindrical portion 12 and is integrated with the cylindrical portion 12. The joint rod 26 passes through the top surface of the top cover case 16 and is rotatably supported by the top cover case 16. Therefore, even when the joint rod 26 (shaft 22) is driven to rotate, the cylindrical portion 12 does not rotate with the joint rod 26 (shaft 22) and remains free to move.

The attachment 10 further includes a rotational drive force transmission unit and a reverse prevention unit within the top cover case 16. The rotational drive force transmission unit is a one-way clutch mechanism C1 that automatically rotates the helical portion 14 (joint rod 26 and shaft 22) and the cylindrical portion 12 as a single unit when driving the helical portion 14 in the rotational direction during excavation. This allows the soil excavated by the helical portion 14 to be discharged to the ground using the fins 13 on the cylindrical portion 12, as described above. On the other hand, when driving the helical portion 14 in the direction opposite to the rotational direction during excavation, the rotational drive force transmission unit rotates the helical portion 14 in the reverse direction, applying pressure to the crushed stone and interrupting the transmission of power from the helical portion 14 (joint rod 26 and shaft 22) to the cylindrical portion 12, stopping the rotation of the cylindrical portion 12. When driving the helical portion 14 in the direction opposite to the rotation direction during excavation, the anti-reverse portion restricts the rotation of the cylindrical portion 12 so that the stopped cylindrical portion 12 does not rotate in either the excavation rotation direction or the reverse direction. Hereinafter, the direction in which the cylindrical portion 12 and the helical portion 14 rotate in the same direction, i.e., the rotation direction during excavation, will be referred to as the "forward direction," and the direction in which they rotate opposite to the rotation direction during excavation, i.e., the rotation direction in which the helical portion 14 applies pressure to the crushed stone, will be referred to as the "reverse direction." In addition, the forward direction will be described as right rotation (clockwise), and the reverse direction will be described as left rotation (counterclockwise).

The attachment 10 further includes a bearing 57 provided at one end of the cylindrical portion 12. This bearing 57 is specifically provided in the center of the upper end surface of the top cover case 16, and the joint rod 26 is inserted through its center hole.

The cylindrical portion separation prevention mechanism of the attachment 10 of this embodiment will now be described in detail with reference to Figures 4(a) and (b). Because the cylindrical portion separation prevention mechanism is provided in the joint rod 26, the configuration of the joint rod 26 will be described first.

As shown in FIG. 4(a), the joint rod 26 of this embodiment is hollow and has a first end 26a and a second end 26b. The first end 26a is located at the top in FIG. 4(a) and is connected to the output shaft 27 of the drive unit 11. The second end 26b is located at the bottom in FIG. 4(a) and is connected to the upper end of the shaft 22. The joint rod 26 includes a cylindrical main body 61 and a first end member 62 and a second end member 63 attached to the cylindrical main body 61. The cylindrical main body 61 is made of a cylindrical steel pipe having a first opening 26c opening to the first end 26a and a second opening 26d opening to the second end 26b. The cylindrical main body 61 has a rod accommodating space 66 therein. The first end member 62 is a columnar member having a first center hole 64 and a first fitting portion 62c at its lower end. The first fitting portion 62c is fitted into the first opening 26c of the cylindrical main body 61 and is joined to the cylindrical main body 61. The joint between the cylindrical main body 61 and the first end member 62 is fixed by welding. The second end member 63 is a cylindrical member having a second center hole 65 and an expanded diameter space 63b communicating therewith, and has a second fitting portion 63c at its upper end. The second fitting portion 63c is fitted into the second opening 26d of the cylindrical main body 61 and is joined to the cylindrical main body 61. The joint between the cylindrical main body 61 and the second end member 63 is fixed by welding. The cylindrical main body 61, located midway between the first end 26a and the second end 26b of the joint rod 26, is rotatably supported on its outer circumferential surface by the bearing portion 57.

As shown in FIG. 4(b), a core member 71 is disposed inside the joint rod 26 of this embodiment to maintain the first end 26a and second end 26b of the joint rod 26 in a connected state even if the joint rod 26 breaks. The core member 71 is a component constituting the main part of the mechanism that maintains the cylindrical portions in a connected state and is made of a metal rod with a circular cross section. Most of the core member 71 is located within the rod accommodating space 66 of the cylindrical main body 61. The upper end 71a of the core member 71 is inserted through the first center hole 64 of the first end member 62 and extends to the upper end opening 62a of the first center hole 64. In this state, the upper end 71a of the core member 71 is welded and fixed to the first end member 62. Meanwhile, the lower end 71b of the core member 71 is fitted into the second center hole 65 of the second end member 63 and is thereby fixed to the second end member 63. As a result, the upper end 71a of the core material 71 is welded to the first end member 62 on the first opening 26c side, and the lower end 71b is fitted into the second end member 63 on the second opening 26d side. This ensures that the first end member 62 and the second end member 63 remain connected to each other even if the joint rod 26 breaks.

Next, we will explain the operation of the crushed stone pile forming device 100 when it forms a crushed stone pile.

First, the attachment 10 is aligned. The attachment 10 is aligned by adjusting the position and direction of the soil improvement machine 40 by driving the crawlers 6. After adjusting the position and direction of the soil improvement machine 40, the soil improvement machine 40 may be fixed to the ground by the outriggers 5. This makes it possible to prevent the soil improvement machine 40 from shaking or shifting position during construction.

The attachment 10 is then inserted into the ground to excavate it. Specifically, after the soil improvement machine 40 is fixed to the ground, the drive unit 11 is driven to lower the attachment 10. At this time, the drive unit 11 is driven to generate a rotational drive force in the forward direction. As described above, when the drive unit 11 generates a rotational drive force in the forward direction, the rotational drive force transmission unit rotates the spiral portion 14 and cylindrical portion 12 in the forward direction. This allows the attachment 10 to be inserted into the ground and excavate it. The soil and sand discharged by the excavation in the ground is carried to the outer periphery of the cylindrical portion 12 and discharged to the surface by the fins 13. When the attachment 10 reaches a predetermined depth, the forward rotation of the drive unit 11 is stopped, and excavation ends.

Next, the attachment 10 is raised, and a crushed stone pile is formed in the ground. The crushed stone pile is formed as follows: First, with the opening/closing door 20 open, crushed stone is loaded into the crushed stone loading device 32. The crushed stone loaded into the crushed stone loading device 32 is then dumped into the cylindrical portion 12 through the crushed stone loading hole 15. Next, the drive unit 11 is driven to generate a rotational driving force in the reverse direction. The spiral portion 14 then rotates in the reverse direction, pushing the crushed stone loaded into the cylindrical portion 12 out of the cylindrical portion 12. This pushes the attachment 10 out of the ground, and a crushed stone pile is formed in the space formed by the cylindrical portion 12. As described above, when the drive unit 11 generates a rotational driving force in the reverse direction, only the spiral portion 14 rotates in the reverse direction due to the rotational driving force transmission unit, and the cylindrical portion 12 does not rotate in either the forward or reverse direction. This prevents the position of the crushed stone injection hole 15 provided in the cylindrical portion 12 from changing circumferentially, and allows crushed stone to be injected into the cylindrical portion 12 without adjusting the position of the crushed stone injection device 32. Then, when the attachment 10 is pushed out to the ground surface, the driving device 11 stops driving in the reverse direction, completing the formation of the crushed stone pile.

In this type of attachment 10, the joint rod 26 is rotatably supported by the bearing 57 at a position midway between the upper end 26a and the lower end 26b. Therefore, large stresses tend to concentrate at the point on the joint rod 26 where the bearing 57 supports it, which could cause the joint rod 26 to break (fracture) near that point (for example, position P1 shown in Figure 3).

Therefore, in the attachment 10 of this embodiment, a core material 71 is disposed within the hollow joint rod 26 that connects the output shaft 27 and the shaft 22. The core material 71 connects the first end 26a and the second end 26b of the joint rod 26 so that they remain connected even if the joint rod 26 breaks. Therefore, in the attachment 10 described above, even if the joint rod 26 breaks midway, the upper end 71a of the core material 71 housed therein engages with the first end 26a, and the lower end 71b of the core material 71 engages with the second end 26b, maintaining the connected state between the first end 26a and the second end 26b (i.e., the connected state between the output shaft 27 side and the shaft 22 side is maintained). This prevents the cylindrical portion 12 from unintentionally falling off the drive device 11. This prevents the cylindrical portion 12 from unintentionally separating from the drive device 11 and tipping or rolling. Furthermore, when transporting the soil improvement machine 40, as shown in FIG. 7, it may be transported with the attachment 10 attached to the soil improvement machine 40. That is, the soil improvement machine 40 may be transported with the leader 4 horizontal, thereby horizontally positioning the attachment 10. In this case, if the core material 71 is not installed, if the joint rod 26 breaks, there is a possibility that the attachment 10 will fall off the drive unit 11 and onto the ground. However, in the soil improvement machine 40 of this embodiment, the core material 71 is disposed within the joint rod 26, and the core material 71 maintains the connection between the drive unit 11 and the attachment 10. This prevents the attachment 10 from unintentionally falling off when the soil improvement machine 40 is transported.

In addition, in the joint rod 26 of this embodiment, the upper end 71a of the core material 71 is inserted through the first central hole 64 of the first end member 62 and is welded and fixed to the first end member 62. This allows the upper end 71a of the core material 71 to be firmly fixed (an example of locking) to the first end member 62.

In addition, in the joint rod 26 of this embodiment, the lower end 71b of the core material 71 is fitted (an example of locking) into the second center hole 65 of the second end member 63, and the second end member 63 side of the joint rod 26 is disposed inside the cylindrical portion 12. Therefore, the core material 71 restricts movement of the second end member 63 in the direction perpendicular to its axis, and as a result, the cylindrical portion 12 restricts movement of the second end member 63 (and the shaft 22) in the direction perpendicular to its axis. Therefore, even if the lower end 71b of the core material 71 is not welded to the second end member 63, it is possible to prevent the lower end 71b of the core material 71 from coming off the second center hole 65 of the second end member 63. Therefore, even if the lower end 71b of the core material 71 is located in a location where welding is difficult, it is relatively easy to secure the lower end 71b of the core material 71 to the second end member 63.

In the joint rod 26 of this embodiment described above, the upper end 71a of the core material 71 is inserted through the first center hole 64 of the first end member 62 and welded to the upper end opening 62a of the first end member 62. However, this is not limited to this, and the upper end of the core material can be engaged with the first end member in various ways. For example, in another embodiment of the joint rod 26A shown in FIG. 5, a support recess 62b is formed in the upper end opening 62a of the first center hole 64 of the first end member 62. Furthermore, a first enlarged diameter portion 72 having a diameter larger than the first center hole 64 is formed in the upper end 71a of the core material 71. The first enlarged diameter portion 72 may then be supported by the support recess 62b. When assembling the joint rod 26A, the lower end 71b of the core material 71 is inserted through the upper end opening 62a of the first center hole 64. With this configuration, even if a force is applied to the core 71 in a direction that separates the first end member 62 and the upper end 71a of the core 71 (i.e., a force that pulls the core 71 downward in the figure), the first expanded diameter portion 72 does not pass through the first center hole 64 but abuts against the support recess 62b and is supported. Therefore, even if the upper end 71a of the core 71 is not fixed to the first end member 62 by welding or the like, the upper end 71a of the core 71 is held (locked) without slipping out of the first end member 62. Note that, while the first expanded diameter portion 72 is cylindrical in the alternative embodiment shown in FIG. 5, this is not limiting and the shape may be, for example, rectangular, spherical, or conical.

In addition, in the joint rod 26 of this embodiment, the lower end 71b of the core material 71 is fitted into the second center hole 65 of the second end member 63. However, this is not limited to this, and the lower end of the core material can be engaged with the second end member in various ways. For example, in another embodiment of the joint rod 26B shown in FIG. 6, an expanded diameter space 63b is formed in the lower end opening 63a of the second center hole 65 of the second end member 63. A second expanded diameter portion 73 having a larger diameter than the second center hole 65 is formed in the lower end 71b of the core material 71. This second expanded diameter portion 73 may be disposed within the expanded diameter space 63b. When assembling the joint rod 26B, the upper end 71a of the core material 71 is inserted through the lower end opening 63a of the second center hole 65. With this configuration, even if a force is applied to the core 71 in a direction that separates the second end member 63 and the lower end 71b of the core 71 (i.e., a force that pulls the core 71 upward in the figure), the second expanded diameter portion 73 does not pass through the second center hole 65 and remains supported within the expanded diameter space 63b. Therefore, even if the lower end 71b of the core 71 is not fixed to the second end member 63 by welding or the like, the lower end 71b of the core 71 is retained (locked) without slipping out of the second end member 63. Note that, while the second expanded diameter portion 73 is spherical in the alternative embodiment shown in FIG. 6, this is not limiting and may be, for example, rectangular, cylindrical, or conical.

Furthermore, in this embodiment, a metal rod is used as the core material 71, but this is not limited to this. For example, in another embodiment shown in Figures 5 and 6, a metal wire may be used as the core material 71. That is, the configuration shown in Figure 5 may be used for the upper end of the core material 71, and the configuration shown in Figure 6 may be used for the lower end of the core material 71. Whether this configuration is used or a metal wire is used for the core material 71, the cylindrical portion 12 and the drive unit 11 (output shaft 27) can be maintained in a connected state.

In addition, in this embodiment, compaction by reverse rotation of the screw of the attachment 10 was used as a method for pouring crushed stone into a space formed underground to form a crushed stone pile, but this is not limited to this example. The technology disclosed in this specification can also be used in crushed stone pile formation methods that do not rely on compaction by reverse rotation of the screw of the attachment 10.

In addition, while the present embodiment illustrates an attachment 10 that discharges excavated soil to the ground surface (a so-called soil discharge type), the present invention is not limited to this example. The technology disclosed in this specification can also be used in attachments that do not discharge soil, for example.

The above provides a detailed description of specific examples of the technology disclosed in this specification. However, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. For example, in the above embodiment, soil is excavated when the cylindrical portion rotates clockwise. However, this is not limited to such examples. The scope of the present invention also includes a configuration in which soil is excavated when the cylindrical portion rotates in the opposite direction to the above embodiment, or a configuration in which the fixed position of the opening and closing door is reversed from the left to the right to the above embodiment. Furthermore, the technical elements described in this specification or drawings may demonstrate technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

10 Attachment 11 Drive device 12 Cylindrical portion 15 Crushed stone injection hole 22 Shaft 26, 26A, 26B Joint rod 26a First end 26b Second end 26c First opening 26d Second opening 27 Output shaft 57 Bearing portion 61 Cylindrical main body 62 First end member 62a Upper end opening 62b Support recess 63 Second end member 63a Lower end opening 63b Expanded diameter space 64 First central hole 65 Second central hole 71 Core material 72 First expanded diameter portion 73 Second expanded diameter portion 100 Crushed stone pile forming device

Claims (5)

An attachment for forming a crushed stone pile is attached to a crushed stone pile forming device that forms a crushed stone pile in a space formed in the ground, is inserted into the ground to form the space, and forms a crushed stone pile in the space while rising from the ground,
a cylindrical portion having a crushed stone injection hole formed on its side;
a shaft rotatably disposed within the cylindrical portion and rotated by a driving force from a driving device;
a hollow joint rod having a first end and a second end, the first end being connected to an output shaft of the drive device and the second end being connected to the shaft;
a core member disposed within the joint rod, the upper end of which is engaged with the first end of the joint rod and the lower end of which is engaged with the second end of the joint rod;
An attachment for forming crushed stone piles. The attachment for forming crushed stone piles described in claim 1, wherein the joint rod comprises a cylindrical body having a first opening on the first end side and a second opening on the second end side, a first end member joined to the first opening of the cylindrical body, and a second end member joined to the second opening of the cylindrical body. The attachment for forming a crushed stone pile described in claim 2, wherein the upper end of the core material is inserted through a first central hole of the first end member and welded to the first end member. The attachment for forming a crushed stone pile described in claim 2, wherein the lower end of the core material is fitted into a second central hole of the second end member. a support recess is formed at an upper end opening of a first center hole of the first end member;
a first enlarged diameter portion having a diameter larger than that of the first central hole is formed at an upper end of the core material;
The crushed stone pile forming attachment according to claim 2 , wherein the first enlarged diameter portion is supported by the support recess.