JP6843348B2 - Crushed stone pile forming device and manufacturing method of crushed stone pile - Google Patents

Description

The technique disclosed herein relates to a crushed stone pile forming apparatus and a method for manufacturing a crushed stone pile.

A method of forming crushed stone piles in the ground is used for ground improvement such as liquefaction countermeasures. For example, the crushed stone pile forming device disclosed in Patent Document 1 includes an attachment that is inserted into the ground to form a space and forms a crushed stone pile in the space while rising from the ground. The attachment includes a cylindrical portion and a spiral portion that is rotatably arranged within the cylindrical portion and excavates the ground. Fins arranged in a spiral shape are provided on the outer circumference of the cylindrical portion. The spiral part excavates the ground while inserting the attachment by rotating in the forward rotation direction. Crushed stone is thrown into the internal space of the cylindrical part, and the spiral part forms a crushed stone pile while pulling out the attachment by rotating in the reverse direction.

Japanese Unexamined Patent Publication No. 7-127044

The crushed stone pile forming device of Patent Document 1 forms a space for forming a crushed stone pile by excavating the spiral portion in the ground. The earth and sand excavated by the spiral portion is discharged to the ground surface by the fins provided on the outer circumference of the cylindrical portion through the space for forming the crushed stone pile and the outer circumference of the cylindrical portion. However, a part of earth and sand may enter the cylindrical portion from the tip of the spiral portion. If earth and sand enter the cylindrical portion from the tip of the spiral portion, the crushed stones thrown into the internal space of the cylindrical portion and the earth and sand invaded from the spiral portion are mixed, and the strength of the formed crushed stone pile may decrease. The present specification discloses a technique for suppressing a decrease in the strength of a crushed stone pile.

The crushed stone pile forming apparatus disclosed in the present specification forms a crushed stone pile in the space formed in the ground. The crushed stone pile forming device is an attachment that is inserted into the ground to form a space and forms a crushed stone pile in the space while rising from the ground, a driving device that generates a rotational driving force, and an attachment that is installed on the ground surface. It is provided with a crushed stone holder having a through hole through which it can be penetrated. The attachment includes a cylindrical portion and a spiral portion that is rotatably arranged within the cylindrical portion and is connected to a drive device to excavate the ground. The crushed stone holder is configured so that crushed stone can be thrown into the space inside the through hole surrounded by the tip of the attachment, the ground surface, and the crushed stone holder before the attachment is inserted into the ground. In the state after the attachment is inserted into the ground, the attachment is inserted into the ground in a state of penetrating the through hole of the crushed stone holder.

In the above-mentioned crushed stone pile forming device, the crushed stone holder is configured so that crushed stone can be thrown into the space inside the through hole before the attachment is inserted into the ground, and the attachment is inserted into the ground. In the later state, the attachment is configured to penetrate the through hole. That is, when forming a crushed stone pile, first, the crushed stone holder is installed on the ground surface, and the attachment is positioned at the position of the through hole of the crushed stone holder. Then, before the attachment is inserted into the ground, the crushed stone is thrown into the space inside the through hole of the crushed stone holder. After that, the attachment penetrates through the through hole in the state where the crushed stone is thrown and is inserted into the ground. At that time, the crushed stone can be arranged at the tip of the spiral portion by penetrating the through hole while the spiral portion of the attachment rotates. That is, the crushed stone is pressed toward the ground surface by the pressure when the spiral portion excavates the ground, and the crushed stone is held by the tip of the spiral portion and the cylindrical portion. Then, the spiral portion can be excavated in the ground while holding the crushed stone at its tip. As a result, it is possible to prevent the earth and sand discharged by excavation in the ground from entering the cylindrical portion from the tip of the spiral portion. Therefore, it is possible to suppress the mixing of earth and sand into the crushed stone pile, and it is possible to suppress a decrease in the strength of the crushed stone pile.

Further, in the method for manufacturing a crushed stone pile disclosed in the present specification, the crushed stone pile includes a cylindrical portion and a spiral portion rotatably arranged in the cylindrical portion and connected to a drive device to excavate the ground. It is formed using an attachment for forming crushed stone piles. The method of manufacturing the crushed stone pile is an excavation process in which the spiral part and the cylindrical part are integrally rotated by a drive device to excavate the ground while inserting the attachment into the ground, and the attachment is inserted into the ground. It is equipped with a crushed stone throwing step of throwing crushed stone into the space inside the cylindrical part formed in the ground and a forming step of forming a crushed stone pile with the crushed stone thrown into the cylindrical part while raising the attachment from the ground. There is. In the excavation process, the attachment is inserted into the ground while holding the crushed stone supplied from the tip side of the spiral portion at least at the tip of the spiral portion.

In the above method for manufacturing a crushed stone pile, in the excavation process, the attachment excavates the ground while holding the crushed stone at at least the tip of the spiral portion. Therefore, the same effect as that of the above-mentioned crushed stone pile forming device can be obtained.

The figure which shows the schematic structure of the crushed stone pile forming apparatus which concerns on Example. The cross-sectional view which shows the structure of the cylindrical part and the spiral part of the attachment which concerns on Example. The perspective view which shows the crushed stone holder which concerns on Example. Top view showing the crushed stone holder according to the Example. The flowchart which shows the manufacturing method of the crushed stone pile using the crushed stone pile forming apparatus which concerns on Example. It is a figure which shows the manufacturing method of the crushed stone pile using the crushed stone pile forming apparatus which concerns on an Example, and shows the state which installed the crushed stone holder. It is a figure which shows the manufacturing method of the crushed stone pile using the crushed stone pile forming apparatus which concerns on an Example, and shows the state which put the crushed stone into the crushed stone holder. It is a figure which shows the manufacturing method of the crushed stone pile using the crushed stone pile forming apparatus which concerns on an Example, and shows the state which inserted the attachment into the crushed stone holder. It is a figure which shows the manufacturing method of the crushed stone pile using the crushed stone pile forming apparatus which concerns on an Example, and shows the state which the attachment is excavating in the ground.

The main features of the examples described below are listed. It should be noted that the technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Absent.

(Characteristic 1) In the crushed stone pile forming apparatus disclosed in the present specification, the driving device may generate rotational driving forces in the forward rotation direction and the reverse rotation direction. Further, the spiral portion may be excavated in the ground by rotation in the forward rotation direction, and pressure may be applied to the crushed stone by rotation in the reverse rotation direction. According to such a configuration, the spiral portion can excavate a space for forming a crushed stone pile in the driving of the forward rotation, and can apply pressure to the crushed stone in the driving in the reverse direction. Therefore, the main work from excavation to formation of crushed stone piles can be performed consistently.

(Characteristic 2) In the crushed stone pile forming apparatus disclosed in the present specification, the attachment may further include a crushed stone storage portion for storing crushed stone to be charged into the cylindrical portion. Further, the amount of crushed stone that can be stored in the crushed stone storage unit at one time may be greater than or equal to the total amount of crushed stone required to form a crushed stone pile. With such a configuration, the crushed stone storage section can store the entire amount of crushed stone required to form a crushed stone pile. Therefore, the entire amount of crushed stone, which is the material of the crushed stone pile, can be charged by one loading operation. Therefore, it is not necessary to additionally add crushed stone when forming the crushed stone pile, and the crushed stone pile can be formed efficiently in a short time.

(Feature 3) In the method for manufacturing a crushed stone pile disclosed in the present specification, an installation process of installing a crushed stone holder having a through hole through which an attachment can penetrate is installed on the ground surface, and an installed crushed stone holder and an attachment before the excavation process. By inserting the attachment into the through hole of the crushed stone holder while rotating the spiral part and the cylindrical part integrally by the driving device, the spiral part is thrown into the space inside the through hole surrounded by the tip and the ground surface. The step of holding the crushed stone charged in the charging step at least at the tip of the portion may be executed. According to such a configuration, the crushed stone holder can be arranged on the ground surface and the crushed stone can be arranged in the through hole of the crushed stone holder before the excavation process. Therefore, before the excavation process, crushed stone can be supplied from the tip end side of the spiral portion to suitably hold the crushed stone at least at the tip end of the spiral portion.

The crushed stone pile forming apparatus 100 according to this embodiment will be described. As shown in FIG. 1, the crushed stone pile forming device 100 includes a ground improvement machine 50 as a construction machine, an attachment 10 mounted on the ground improvement machine 50, and a crushed stone holder 30 supported by the ground improvement machine 50. I have. As shown in FIG. 1, the ground improvement machine 50 includes a ground improvement machine main body structure 1, a cabin 7 as a driver's seat, a crawler 6 which is an endless track capable of moving on rough terrain with low ground pressure, and a construction time. The outrigger 5 that suppresses the swing of the ground improvement machine 50 is provided. The size of the ground improvement machine 50 is not particularly limited, but for example, one of 10 tons or more and 15 tons or less can be preferably used, and in this embodiment, one of 10 tons is used. That is, the crushed stone pile forming device 100 of this embodiment forms a crushed stone pile having a relatively small underground depth of about 5 m, and a small one can be used as the ground improvement machine 50.

The ground improvement machine 50 further includes a drive device 11 that supplies a rotational driving force to the attachment 10 via a motor output shaft 27, a leader 4 having an elevating guide rail 9, and a leader as a configuration for operating the attachment 10. It includes a leader mounting base 2 for supporting the leader 4, a hydraulic cylinder 3 for controlling the inclination of the leader 4, and an extension pedestal 8 integrally formed with the leader 4 at the lower end of the leader 4. ..

The attachment 10 includes a cylindrical portion 12 provided with fins 13, a spiral portion 14, a hanger stay 64 having a bifurcated fork shape, a top cover case 55 having a cam convex 63, and crushed stone used as a material for a crushed stone pile. It is provided with a crushed stone storage unit 15 capable of storing the crushed stone, and a construction management device 51 for managing the construction state by the attachment 10.

FIG. 2 is a cross-sectional view showing the configuration of the cylindrical portion 12 and the spiral portion 14. In FIG. 2, the crushed stone storage unit 15 is not shown. The spiral portion 14 is integrally formed with the rotary input shaft 26 and the core rod 22. The rotary input shaft 26 is connected to the motor output shaft 27 of the drive device 11. The rotary input shaft 26 rotates according to the rotational driving force of the motor output shaft 27, and transmits the rotational driving force to the spiral portion 14 via the integrally coupled core rod 22. An excavation blade is provided at the tip of the spiral portion 14. The excavation blade is formed in a spiral shape in which the diameter increases toward the tip of the spiral portion 14. Approximately the entire excavation blade is arranged in the cylindrical portion 12, and only a part of the tip of the excavation blade protrudes from the tip of the cylindrical portion 12.

The core rod 22 is rotatably connected to the cylindrical portion 12 by the bearing tube 23 and the radiation stay 24, and shares the rotating shaft with the cylindrical portion 12. On the other hand, the cylindrical portion 12 has spiral fins 13 around it. The fin 13 has a spiral shape in the same direction as the spiral of the spiral portion 14 (that is, the excavation blade). That is, when excavating, the cylindrical portion 12 and the spiral portion 14 rotate in the same direction. As a result, the excavated earth and sand generated by the excavation of the spiral portion 14 is transported to the ground surface by the fins 13. The diameter of the cylindrical portion 12 is not particularly limited and can be appropriately determined according to the diameter of the crushed stone pile to be formed. For example, it can be 150 mm or more and 400 mm or less, and is set to 165 mm in this embodiment. By setting the diameter of the cylindrical portion 12 to 150 mm or more, it is possible to form a space for forming a crushed stone pile having strength suitable for ground improvement. On the other hand, by setting the diameter of the cylindrical portion 12 to 400 mm or less, it is possible to form a crushed stone pile using a relatively small ground improvement machine 50.

The attachment 10 further includes a one-way clutch mechanism (not shown) between the rotation input shaft 26 and the core rod 22 inside the top cover case 55. The one-way clutch mechanism is in an operating state in which the spiral portion 14 and the cylindrical portion 12 automatically rotate as a unit when driven in the rotational direction during excavation. As a result, the earth and sand excavated by the spiral portion 14 as described above can be discharged to the ground by the fins 13 of the cylindrical portion 12. On the other hand, in the rotational drive in the direction opposite to the rotational direction during excavation, the spiral portion 14 can apply pressure to the crushed stone and the cylindrical portion 12 can automatically stop the rotation. Hereinafter, the direction in which the cylindrical portion 12 and the spiral portion 14 rotate in the same direction, that is, the rotation direction during excavation is referred to as a "forward rotation direction", and the direction in which the spiral portion 12 rotates in the direction opposite to the rotation direction during excavation, that is, the spiral portion. The direction of rotation in which pressure is applied to the crushed stone at 14 is sometimes referred to as the "reversal direction". In this embodiment, the cylindrical portion 12 is provided with the fin 13, but the configuration is not limited to this. For example, when forming a crushed stone pile on soft ground, it is not necessary to discharge the earth and sand to the ground surface, so that the fins of the cylindrical portion can be omitted. That is, in soft ground, unnecessary earth and sand can be compressed and compacted around the space for forming crushed stone piles during excavation. When forming a crushed stone pile in such soil, it is not necessary to discharge the earth and sand to the ground surface, so that an attachment having a cylindrical portion without fins can be used.

The crushed stone storage portion 15 is a hopper that supplies crushed stone to the inside of the cylindrical portion 12, and is arranged above the cylindrical portion 12. The upper end and the lower end of the crushed stone storage portion 15 are open. The opening at the upper end of the crushed stone storage portion 15 is wider than the opening at the lower end. The opening at the lower end of the crushed stone storage portion 15 communicates with the internal space of the cylindrical portion 12. Therefore, the crushed stone storage unit 15 can store the crushed stone and can send the crushed stone charged into the crushed stone storage unit 15 to the internal space of the cylindrical portion 12. When the crushed stone sent out from the crushed stone storage unit 15 is filled in the entire internal space of the cylindrical portion 12, the crushed stone is stored in the through hole of the crushed stone storage unit 15. In such a crushed stone loading operation from the crushed stone storage portion 15, the amount of crushed stone that can be continuously charged at one time (the amount of crushed stone that can be charged into the internal spaces of the crushed stone storage portion 15 and the cylindrical portion 12) is determined by using a crushed stone pile. It is preferable that the total amount of crushed stone required for formation (the amount of crushed stone forming one crushed stone pile) is larger than the total amount of crushed stone, and the amounts of both are substantially the same. If the amount of crushed stone that can be put into the internal space of the crushed stone storage part 15 and the cylindrical part 12 is less than the amount of crushed stone that forms one crushed stone pile, it is necessary to additionally put crushed stone in the middle of forming the crushed stone pile. Will occur. On the other hand, if the amount of crushed stone that can be put into the crushed stone storage unit 15 is excessively larger than the amount of crushed stone that forms one crushed stone pile, the crushed stone storage unit 15 becomes unnecessarily large. As described above, the crushed stone storage portion 15 is arranged above the cylindrical portion 12. Therefore, if the crushed stone storage portion 15 becomes large, it becomes unstable when the attachment 10 is fixed to the crushed stone pile forming device 100. In order to solve this problem, it will be necessary to make the leader 4 thicker or use a larger ground improvement machine 50. In the crushed stone storage unit 15 of this embodiment, the entire amount of crushed stone forming one crushed stone pile can be charged by one charging operation, and the crushed stone cannot be excessively stored. Therefore, it is not necessary to additionally add crushed stone at the time of forming the crushed stone pile, the crushed stone pile can be formed in a short time, and the work efficiency can be improved.

As shown in FIGS. 3 and 4, the crushed stone holder 30 includes a main body portion 31 and a crushed stone input portion 32. The main body 31 of the crushed stone holder 30 is provided with a through hole 34 in the coaxial direction with the attachment 10. The through hole 34 is formed in a size that allows the attachment 10 to penetrate. Note that in FIGS. 3 and 4, the holder support portion 16 described later is not shown. The main body 31 is a tubular member whose outer shape is substantially hexagonal when viewed from the axial direction, and the crushed stone input portion 32 is connected to one side (the left side in FIG. 4) of the substantially hexagon. There is. The height dimension of the main body 31 is when the tip of the attachment 10 abuts on the ground surface for excavating the ground (that is, when the attachment 10 is installed upright on the ground surface (shown in FIG. 8). In the state)), the upper end of the main body 31 is set to be located above the tip of the cylindrical portion 12. As a result, an appropriate amount of crushed stone can be held in the crushed stone holder 30 before excavation in the ground by the attachment 10. The crushed stone input portion 32 is configured so that the lower portion coincides with one side of the main body portion 31, and the upper portion is arranged outside the outer periphery of the main body portion 31. Further, as shown in FIG. 1, the crushed stone holder 30 is supported by the extension pedestal 8 by the holder support portion 16. It is supported by the extension pedestal 8 so that the central axis of the crushed stone holder 30 and the central axis of the attachment 10 substantially coincide with each other. Therefore, the attachment 10 penetrates the through hole 34 of the crushed stone holder 30 during excavation and pressure application.

A method of manufacturing a crushed stone pile using the crushed stone pile forming apparatus 100 will be described with reference to FIGS. 5 to 9. As shown in FIG. 5, first, the crushed stone holder 30 is installed at the crushed stone pile forming position on the ground surface (S10). The alignment of the crushed stone holder 30 is performed by adjusting the position and direction of the ground improvement machine 50 by driving the crawler 6. After adjusting the position and direction of the ground improvement machine 50, the ground improvement machine 50 is fixed by the outriggers 5. As a result, it is possible to suppress swinging and misalignment of the ground improvement machine 50 during construction. After fixing the ground improvement machine 50, the crushed stone holder 30 is lowered to a position where it touches the ground surface. The crushed stone holder 30 may be brought into contact with the ground surface without a gap, or a gap may be formed between the crushed stone holder 30 and the ground surface. However, when grounding so as to generate a gap, it is preferable that the gap is smaller than the size of the crushed stone.

The step of installing the crushed stone holder 30 in S10 is performed in a state where the attachment 10 is raised by the leader 4. That is, as shown in FIG. 6, the tip of the attachment 10 is arranged above the crushed stone holder 30. As a result, the crushed stone holder 30, the ground surface, and the space 35 surrounded by the attachment 10 (see FIGS. 4 and 6) are formed. That is, the side surface of the space 35 is surrounded by the crushed stone holder 30, the lower surface is surrounded by the ground surface, and the tip of the attachment 10 is arranged in the upper part of the space 35. As is clear from the figure, the crushed stone holder 30 and the attachment 10 are separated from each other, and the space 35 is an unclosed space.

Next, the crushed stone is put into the through hole 34 of the crushed stone holder 30 (S12). That is, crushed stone is thrown into the space 35. In the present specification, crushed stone has a broad meaning and includes natural objects such as natural crushed stone, gravel and sand, or man-made objects such as concrete fragments, waste tiles and mines. However, if natural objects are used, soil contamination due to ground improvement can be prevented, and the need for future removal of artificial objects can be eliminated in advance by not leaving artificial objects in the ground. Therefore, there is an advantage that the decline in the asset value of the land can be suppressed. On the other hand, if waste such as concrete fragments is used, there is an advantage that the waste can be effectively used as a material for ground improvement. As described above, the crushed stone holder 30 includes a crushed stone input portion 32. Therefore, as shown in FIG. 7, even when the tip of the attachment 10 is arranged in the vicinity of the crushed stone holder 30, the crushed stone can be thrown into the space 35 from the crushed stone throwing portion 32.

In this embodiment, the crushed stone holder 30 includes the crushed stone input portion 32, but the configuration is not limited to this. For example, the crushed stone holder may be configured not to include the crushed stone input portion 32, or may be configured in a tubular shape having a substantially hexagonal shape when the crushed stone holder is viewed in the axial direction. When such a crushed stone holder is used, in the crushed stone holder installation step in S10, the attachment 10 is raised so that a wider space is created between the crushed stone holder and the tip of the attachment 10 than in the state shown in FIG. It is preferable to arrange them. As a result, in the crushed stone charging step of S12, the crushed stone can be easily charged into the through hole of the crushed stone holder.

Next, the spiral portion 14 holds the crushed stone (S14). That is, as shown in FIG. 8, the attachment 10 is inserted into the through hole 34 of the crushed stone holder 30. At this time, while driving the drive device 11, the attachment 10 arranged on the upper part of the crushed stone holder 30 is lowered. The drive device 11 drives the cylindrical portion 12 and the spiral portion 14 so as to rotate in the forward rotation direction. Therefore, the attachment 10 is inserted into the through hole of the crushed stone holder 30 while rotating in the forward rotation direction. Since the spiral portion 14 enters the crushed stone holder 30 while rotating, the crushed stone in the through hole is inserted while being taken in between the spirals (excavation blades) of the spiral portion 14. A part of the crushed stone taken in between the spirals (excavation blades) of the spiral portion 14 also enters the cylindrical portion 12. Therefore, when the spiral portion 14 penetrates the through hole 34 of the crushed stone holder 30 and reaches the ground surface, the crushed stone is held at the tips of the spiral portion 14 and the cylindrical portion 12 (state shown in FIG. 8).

Next, the attachment 10 is inserted into the ground to excavate the ground (S16). As shown in FIG. 9, after the spiral portion 14 penetrates the through hole 34 and reaches the ground surface, the attachment 10 is further lowered and the underground portion is excavated by the spiral portion 14. At this time, similarly to S14, the driving device 11 is driven so that the cylindrical portion 12 and the spiral portion 14 rotate in the forward rotation direction. That is, in S14 and S16, the cylindrical portion 12 and the spiral portion 14 are continuously rotated in the forward rotation direction. Therefore, the crushed stone introduced in S14 is held at the tip of the spiral portion 14, and the attachment 10 is excavated to a predetermined depth while holding the crushed stone at the tip of the spiral portion 14. The crushed stone held at the tips of the spiral portion 14 and the cylindrical portion 12 is pressed upward by the pressure when excavating the ground, and is suitably held by the spiral portion 14 and the cylindrical portion 12. Further, the earth and sand discharged by excavation in the ground is carried to the outer circumference of the cylindrical portion 12 and discharged to the ground surface by the fins 13. At this time, since the crushed stone is held at the tips of the spiral portion 14 and the cylindrical portion 12, it is possible to prevent the earth and sand discharged by excavation from entering the cylindrical portion 12. When the attachment 10 reaches a predetermined depth, the driving of the forward rotation of the driving device 11 is stopped, and the excavation is completed.

Next, the crushed stone is put into the crushed stone storage unit 15 (S18). When the excavation process is completed in S16, the attachment 10 is in a state of being inserted into the ground. That is, the attachment 10 is in a state of being lowered to the lowest position. Therefore, the crushed stone storage portion 15 arranged at the upper part of the attachment 10 moves to a position close to the ground surface. In S18, crushed stone is charged from the crushed stone storage portion 15 arranged near the surface of the earth. At this time, the entire amount of crushed stone required to form one crushed stone pile is input from the crushed stone storage unit 15.

As described above, the amount of crushed stone that can be input from the crushed stone storage unit 15 in one operation is larger than the amount of crushed stone that forms one crushed stone pile. Therefore, in a state where the crushed stone storage portion 15 is arranged near the ground surface, the entire amount of crushed stone forming the crushed stone pile can be charged in one operation. In the crushed stone charging step of S18, since the crushed stone storage portion 15 is lowered to the position closest to the ground surface, the potential energy required for charging the crushed stone can be minimized. If crushed stone is thrown in during the formation of the crushed stone pile, the attachment 10 is higher than the state in S18. That is, the crushed stone storage portion 15 which is the crushed stone input port is also located above. Therefore, since the additional crushed stone input work does not occur, the work time can be shortened and the increase in energy required for the crushed stone input can be suppressed.

Finally, the attachment 10 is raised to form a crushed stone pile in the ground (S20). The formation of the crushed stone pile is performed by discharging the crushed stone while pressurizing it into the space formed by excavation. At this time, the drive device 11 is driven so that the spiral portion 14 rotates in the reverse direction. In the crushed stone charging step of S18, the total amount of crushed stone required to form one crushed stone pile is charged into the cylindrical portion 12 and the crushed stone storage portion 15. Therefore, in S20, the crushed stone pile can be formed without adding additional crushed stone.

In this embodiment, the underground is excavated while holding crushed stone at the tip of the cylindrical portion 12 and the tip of the spiral portion 14. Therefore, it is possible to prevent the earth and sand discharged by excavation from invading the tip of the cylindrical portion 12 and the tip of the spiral (excavation blade) of the spiral portion 14. Therefore, it is possible to reduce the amount of earth and sand mixed in the crushed stone pile, and it is possible to suppress the decrease in the strength of the crushed stone pile.

Further, the crushed stone holder 30 of this embodiment is configured to have a substantially hexagonal shape when viewed from the axial direction. Therefore, as shown in FIG. 4, the dimensions of a straight line passing through the center O of the through hole 34 and having both ends in contact with the crushed stone holder 30 (specifically, the main body 31) (for example, L1 and L2 shown in FIG. 4). ) Are not the same over the entire circumference (hereinafter, the straight lines exemplified by L1 and L2 are referred to as the diameter of the crushed stone holder 30 for convenience of explanation). As a result, two effects can be obtained at the time of excavation and at the time of forming a crushed stone pile. That is, the shortest distance among the diameters of the crushed stone holder 30 is the length of a straight line connecting the center (for example, point 36) and the center O of each side of the hexagon (for example, L1). When the attachment 10 is inserted into the crushed stone holder 30, the gap between the crushed stone holder 30 and the attachment 10 becomes smaller in the vicinity of the point 36. Therefore, the attachment 10 is guided by the crushed stone holder 30, and the swing caused by the raising and lowering of the attachment 10 can be suppressed. On the other hand, the longest distance among the diameters of the through hole 34 is the length of a straight line connecting the apex (for example, point 37) of the hexagon and the center O (for example, L2). When the attachment 10 is inserted into the crushed stone holder 30, the gap between the crushed stone holder 30 and the attachment 10 becomes large in the vicinity of the point 37. Therefore, the earth and sand generated during excavation is likely to be discharged from the ground to the ground surface near the point 37. Therefore, the crushed stone holder 30 of this embodiment can suppress the rocking that occurs when the attachment 10 is raised and lowered, and can suitably discharge the earth and sand generated during excavation. The shape of the crushed stone holder is not particularly limited as long as it is configured so that the crushed stone can be thrown into the space formed by the crushed stone holder and the ground surface. For example, the shape of the crushed stone holder is circular in the axial direction. It may be configured. Even if it is configured in such a shape, it is possible to suppress the invasion of excavated earth and sand into the tips of the cylindrical portion 12 and the spiral portion 14.

In this embodiment, the crushed stone holder 30 is supported by the extension pedestal 8, but the structure is not limited to this. For example, the crushed stone holder may be configured separately from the ground improvement machine 50. Even with such a configuration, if the crushed stone can be thrown into the space between the through hole of the crushed stone holder and the ground surface, and then the attachment 10 can be inserted into the through hole of the crushed stone holder, the cylindrical portion 12 and the spiral portion can be formed. The excavation process can be performed while holding the crushed stone at the tip of 14. Therefore, the same action and effect as in this example can be obtained.

Further, in this embodiment, the crushed stone storage portion 15 is provided above the attachment 10, but the configuration is not limited to this. For example, the structure may be such that the crushed stone can be thrown from the axial side surface of the cylindrical portion of the attachment, or the crushed stone may be thrown in with the attachment raised.

Further, in this embodiment, the ground improvement machine 50 of 10 tons or more and 50 tons or less is used, but the configuration is not limited to this. The size of the ground improvement machine is not limited, and for example, a ground improvement machine of 50 tons or more and 100 tons or less can be used. When such a relatively large ground improvement machine is used, an attachment having a large diameter of the cylindrical portion (for example, 400 mm to 500 mm) can be used, and excavation can be performed to a depth of, for example, 5 m to 30 m. Therefore, the crushed stone pile can be formed deep in the ground. Even with such a configuration, by excavating with the crushed stone held at the tips of the cylindrical portion and the spiral portion using the crushed stone holder 30 of the present embodiment, earth and sand invade the cylindrical portion and the spiral portion. Can be suppressed. That is, if it is an apparatus for forming a crushed stone pile in the space excavated by the spiral portion, the same action and effect as in this embodiment can be obtained by using the same crushed stone holder 30 as in this embodiment. Therefore, the crushed stone pile forming apparatus and the method for manufacturing the crushed stone pile disclosed in the present specification can be applied to various known construction methods for forming the crushed stone pile, for example, a sand compaction construction method, a gravel drain method, a CDP construction method and the like. Can be applied to.

Although specific examples of the techniques disclosed in the present specification have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples illustrated above. In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

4: Leader 8: Extension pedestal 10: Attachment 11: Drive device 12: Cylindrical part 13: Fin 14: Spiral part 15: Crushed stone storage part 30: Crushed stone holder 31: Main body part 32: Crushed stone input part 34: Through hole 35: Space 50: Ground improvement machine 100: Crushed stone pile forming device

Claims (5)

A crushed stone pile forming device that forms crushed stone piles in the space formed in the ground.
An attachment that is inserted into the ground to form the space and rises from the ground to form the crushed stone pile in the space.
A drive device that generates rotational driving force and
It is equipped with a crushed stone holder that is installed on the surface of the earth and has a through hole through which the attachment can penetrate.
The attachment includes a cylindrical portion having an internal space and a spiral portion rotatably arranged in the cylindrical portion and connected to the driving device to excavate the underground.
The crushed stone holder
In the state before the attachment is inserted into the ground, the crushed stone can be thrown into the space in the through hole surrounded by the tip of the attachment, the ground surface and the crushed stone holder.
In the state after the attachment is inserted into the ground, the attachment is inserted into the ground with the attachment penetrating the through hole of the crushed stone holder .
The attachment is a crushed stone pile forming device configured to be able to hold crushed stones thrown into the crushed stone holder in the internal space at the tip of the cylindrical portion during excavation. The driving device generates rotational driving force in the forward rotation direction and the reverse rotation direction.
The crushed stone pile forming apparatus according to claim 1, wherein the spiral portion excavates the underground by rotation in the forward rotation direction and applies pressure to the crushed stone by rotation in the reverse rotation direction. The attachment further includes a crushed stone storage portion for storing crushed stone to be charged into the cylindrical portion.
The crushed stone pile forming apparatus according to claim 1 or 2, wherein the amount of crushed stone that can be stored in the crushed stone storage unit at one time is equal to or more than the total amount of crushed stone required for forming the crushed stone pile. A crushed stone pile formed by using an attachment for forming a crushed stone pile including a cylindrical portion having an internal space and a spiral portion rotatably arranged in the cylindrical portion and connected to a drive device to excavate the ground. It is a manufacturing method of
An excavation process in which the spiral portion and the cylindrical portion are integrally rotated by the drive device to excavate the ground while inserting the attachment into the ground.
A crushed stone throwing step of throwing crushed stone into the space inside the cylindrical portion formed in the ground by inserting the attachment into the ground,
It is provided with a forming step of forming a crushed stone pile by crushed stones thrown into the cylindrical portion while raising the attachment from the ground.
In the excavation step, the crushed stone pile is characterized in that the attachment is inserted into the ground while holding the crushed stone supplied into the internal space from the tip end side of the spiral portion at least at the tip of the spiral portion. Manufacturing method. Before the excavation process
An installation process in which a crushed stone holder having a through hole through which the attachment can penetrate is installed on the ground surface, and
A loading step of loading crushed stone into the space in the through hole surrounded by the installed crushed stone holder, the tip of the attachment, and the ground surface.
By inserting the attachment into the through hole of the crushed stone holder while integrally rotating the spiral portion and the cylindrical portion by the driving device, the crushed stone charged in the charging step is inserted into at least the tip of the spiral portion. The method for manufacturing a crushed stone pile according to claim 4, wherein the step of holding and the step of performing the steps are performed.

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