Site Improvement Devices

Abstract

A ground improvement device that has a simple structure and can reliably be put into an expanded diameter state to excavate a desired area. [Solution] The device comprises a main body portion 10 or a main shaft portion 20 that is connected to a rotary drive device and rotates, a pair of support portions provided on the main shaft portion 20 facing radially, an enlarged head portion 50 rotatably attached to the support portions, and a pair of expansion bars 60 provided on the main shaft portion 20 or the main body portion 10 and capable of engaging with the enlarged head portion 50. When the rotary drive device rotates in reverse, the main body portion 10 and the main shaft portion 20 rotate in reverse and the tip of the enlarged head portion 50 rotates so that the tip of the enlarged head portion 50 is aligned in the radial direction of the main shaft portion 20, and the expansion bars 60 engage with the enlarged head portion 50, rotating the tip of the enlarged head portion 50.

Description

[Technical field]

[0001] The present invention relates to a ground improvement device that excavates and mixes ground, and in particular to a ground improvement device that can expand an excavation area when a predetermined depth is reached. [Background technology]

[0002] Soil improvement, which involves excavating and improving the ground, has been widely practiced in the past. This type of ground improvement is essential for improving the stability of the ground in building foundations and road construction.

[0003] In such ground improvement work, there is a method known as expanded foot consolidation, in which the ground is excavated in the supporting layer using a core excavation method or a pre-boring method, and a foot consolidation bulb is constructed by injecting a foot consolidation liquid (cement milk) into the expanded excavation, thereby increasing the tip bearing capacity of the precast pile.

[0004] In such an expansion foot protection method, an expansion excavation device is used that has an expansion wing that is switched from a reduced-diameter state to an expanded-diameter state by earth pressure when the drilling rod is rotated in the opposite direction, or that has an expansion wing that is switched between a reduced-diameter state and an expanded-diameter state by a fluid pressure cylinder such as hydraulic or water pressure.

[0005] In such a device, the expansion wing is in a contracted state until the predetermined depth is reached, and when the predetermined depth is reached, the expansion wing is in an expanded state, so that the excavation area can be expanded when the predetermined depth is reached without excavating an unnecessary wide area until the predetermined depth is reached, and the work can be performed efficiently. For ground improvement under such conditions, for example, a ground improvement excavator as described in Patent Document 1 has been developed.

[0006] The ground improvement excavator described in Patent Document 1 has an expandable and contractible excavation impeller attached to a drilling rod. The impeller is attached to a pair of brackets arranged opposite to the axial direction of the drilling rod, and swings toward the drilling rod when the drilling rod rotates forward and swings away from the rod due to earth pressure when the drilling rod rotates backward.

[0007] The mixing blade is composed of an arc-shaped reinforcing plate, a shaft, a tip bit, and multiple bits, and is characterized by being contained within the drilling head when the drilling rod is rotating in the forward direction, and by the distance between the bits being more than twice the distance between the tips of the brackets when the rod is rotating in the reverse direction.

[0008] With this ground improvement device, the diameter of the improvement body can be made larger for the same pilot hole diameter, which reduces the number of holes required to improve the same area of ​​ground.In addition, the device is simpler than devices that use fluid pressure cylinders such as hydraulic or water pressure to switch the expansion wings between a reduced diameter state and an expanded diameter state. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2003-301453 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, the ground improvement device described in Patent Document 1 is simple because it does not use a cylinder or the like, but it is expected that the stirring blades will expand due to earth pressure when the excavation rod is reversed, and there are cases where the stirring blades do not expand. If the stirring blades do not expand, it is not possible to excavate the specified area, which can cause a major problem in that it interferes with construction work after excavation.

[0011] The present invention has been proposed to solve the above problems, and has an object to provide a soil improvement device with a simple structure while reliably enlarging the diameter thereof to excavate a desired area. [Means for solving the problem]

[0012] (1) A ground improvement device includes a main body or main shaft connected to a rotary drive device and rotating, a drilling bit provided at the tip of the main shaft, a pair of support parts provided on the main shaft part radially opposed to the base end side of the drilling bit part, an enlarged head part rotatably attached to the support parts, and a pair of expansion bars provided on the main shaft part or the main body part and engageable with the enlarged head part, wherein when the rotary drive device rotates in the forward direction, the main body and the main shaft rotate in the forward direction and the tip of the enlarged head part rotates so that the tip of the enlarged head part is aligned in the circumferential direction of the main shaft part, and when the rotary drive device rotates in the reverse direction, the main body and the main shaft rotate in the reverse direction and the tip of the enlarged head part rotates so that the tip of the enlarged head part is aligned in the radial direction of the main shaft part, and the expansion bars engage with the enlarged head part to rotate the tip of the enlarged head part.

[0013] (2) In the ground improvement device of (1) described above, the main body portion is connected to the rotation drive member, and the main shaft portion is supported by the main body portion and extends in the direction of the rotation axis.

[0014] (3) In the ground improvement device of (1) described above, the expansion bar is journalled to the main shaft portion, and by engaging one end with the expansion head portion and the other end with the support protrusion portion of the main body portion, it assists the expansion head portion in rotating in a direction away from the main shaft portion.

[0015] (4) In the ground improvement device of (2) described above, when the main shaft portion switches from a state in which it rotates synchronously with the forward rotation of the main body portion to a state in which it rotates in reverse, it spins freely for a predetermined angle and then rotates in reverse again in synchronization with the main shaft portion.

[0016] (5) In the ground improvement device of (1) described above, the enlarged head portion is provided with an enlarged display portion that allows confirmation that the tip of the enlarged head portion has rotated so that the tip of the enlarged head portion is aligned radially along the main shaft portion.

[0017] (6) In the ground improvement device of (1) described above, the expansion bar is provided with the other end fixed to the main body portion, and one end is engaged with the expansion head portion to rotate the tip of the expansion head portion.

[0018] (7) The ground improvement system of the present invention comprises a rotary drive device capable of switching between forward and reverse rotation, a main body or main shaft connected to the rotary drive device and rotating, a drilling bit provided at the tip of the main shaft, a pair of support parts provided on the main shaft part radially opposed to the base end side of the drilling bit part, an enlarged head part rotatably attached to the support parts, and a pair of expansion bars provided on the main shaft part or the main body and engageable with the enlarged head part, wherein when the rotary drive device rotates forward, the main body and the main shaft rotate forward and the tip of the enlarged head part rotates so that the tip of the enlarged head part is aligned in the circumferential direction of the main shaft part, and when the rotary drive device rotates reversely, the main body and the main shaft rotate reversely and the tip of the enlarged head part rotates so that the tip of the enlarged head part is aligned in the radial direction of the main shaft part, and the expansion bar engages with the enlarged head part to rotate the tip of the enlarged head part.

[0019] (8) A method of expanding an improvement area of ​​a ground improvement device includes rotating a rotary drive device in the forward direction, rotating a main body and a main shaft in the forward direction in synchronization with the rotary drive device, rotating the rotary drive device in the reverse direction, rotating one of the main body or the main shaft in the reverse direction in synchronization with the rotary drive device, allowing the other of the main body or the main shaft to spin freely for a predetermined angle and then rotating in the reverse direction again in synchronization with the main body or the main shaft, and the reverse rotation of one of the main body or the main shaft causes an expansion bar to engage with the expansion head and rotate the tip of the expansion head. Effect of the Invention

[0020] According to the present invention, the ground improvement device can be simplified in structure and reliably expanded in diameter to excavate a desired area. [Brief description of the drawings]

[0021] [Figure 1] FIG. 2 is a side view showing a ground improvement system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a side view showing the ground improvement device of the ground improvement system shown in FIG. 1 in an expanded diameter state. [Diagram 3] FIG. 2 is a front view showing the soil improvement device of the soil improvement system shown in FIG. 1 in an expanded diameter state. [Figure 4] 1A and 1B are bottom cross-sectional views for explaining the expanded and contracted states of a rotary bit of a ground improvement device according to an embodiment of the present invention, in which (A) shows the expanded state and (B) shows the contracted state. [Diagram 5] A front cross-sectional view showing the main body, main shaft, and enlarged head of the ground improvement device according to the embodiment of the present invention. [Figure 6] 2 is a top cross-sectional view showing the engagement relationship between the main body portion and the main shaft portion of the ground improvement device according to the embodiment of the present invention. FIG. [Figure 7] This is a front view to explain the operation of the expansion bar of the ground improvement device of the embodiment of the present invention, where (A) shows a state in which the expansion bar is in a free position, and (B) shows a state in which the expansion bar is in a position along the rotation axis direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, a ground improvement system S according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the left-right direction in Fig. 1 is referred to as a first direction X, the up-down direction in Fig. 1 is referred to as a second direction Y, and the direction perpendicular to the paper surface in Fig. 1 is referred to as a third direction Z.

[0023] In addition, in the ground improvement system S according to this embodiment, since the rotary drive device 2 rotates around an axis extending in the second direction Y, the second direction Y is also referred to as the rotational axis direction Y or simply the axial direction Y. The rotational direction relative to the rotational axis direction is also referred to as the rotational circumferential direction, and the direction perpendicular to the rotational circumferential direction is also referred to as the rotational radial direction. Furthermore, the downward direction in the rotational axis direction is also referred to as the tip side or tip side, and the upward direction is also referred to as the base side or base direction. In this embodiment, the clockwise direction when viewed from above and below in the second direction Y is described as the forward rotation, and the reverse direction is described as the reverse rotation.

[0024] In addition, in this embodiment, the joining, coupling, and connection of each member and each part is performed by a general appropriate means such as welding, screws, bolts B, and lock pins, unless otherwise specified. <Configuration of Ground Improvement System S> As shown in Fig. 1, the ground improvement system S includes a large base machine 1 such as a pile driver, a rotation drive device 2 such as an auger device attached to the tip of the leader of the base machine 1, and a ground improvement device 3 attached to the rotation drive device 2. According to the ground improvement system S of the present invention, the ground improvement device 3 excavates the ground underground. The rotation drive device 2 rotates around the up-down direction (rotation axis direction Y).

[0025] 2 to 6, the ground improvement device 3 is attached to the tip of the rotation drive device 2 in the rotation axis direction Y. The ground improvement device 3 is formed with a flow path R for injecting a root strengthening liquid (cement milk) or the like into the soil during ground improvement (see FIG. 5).

[0026] The ground improvement device 3 comprises a main body 10 attached to the rotary drive device 2, a main shaft portion 20 extending from the main body portion 10 in the axial direction Y, a drilling bit portion 30 provided at the tip of the main shaft portion 20, a pair of expansion head support portions 40 provided on the main shaft portion 20 at the base end side of the drilling bit portion 30, an expansion head portion 50 rotatably supported on each expansion head support portion 40, and a pair of expansion bars 60 rotatably provided on the main shaft portion 20 at the base end side of the expansion head support portion 40.

[0027] The main body 10 is attached to the tip of the rotation drive device 2 and includes a main body connecting part 11 extending in the rotation axis direction Y, a cylindrical main body support part 12 provided below the main body connecting part 11 and supporting the main shaft part 20, and a plate-shaped screw part 13 provided in a spiral shape around the main body support part 12. The main body 10 is connected to the rotation drive device 2 by the main body connecting part 11, and the rotational force of the rotation drive device 2 is transmitted from the main body connecting part 11, causing each part of the main body 10 to rotate forward or backward integrally.

[0028] The main body support part 12 is provided with a pair of rotational engagement parts 14 having rotational engagement parts 14a, 14b provided opposite to each other on the inner peripheral surface of the cylindrical shape, a first sliding member 15, and a second sliding member 16 (see FIG. 5). The pair of rotational engagement parts 14 are arranged to face each other with a gap therebetween in the circumferential direction. Each rotational engagement part 14 is formed in a roughly fan shape opening at 30° (see FIG. 6). The first sliding member 15 is provided in a portion that contacts a first cylindrical part 22a described below, and the second sliding member 16 is provided in a portion that contacts a third cylindrical part 22c.

[0029] The main shaft portion 20 includes a cylindrical shaft portion 21 extending in the rotation axis direction, and a generally cylindrical shaft support portion 22 coupled to the shaft portion 21 and extending in the rotation axis direction (see FIG. 5). Thus, the main shaft portion 20 extends in the rotation axis direction.

[0030] The shaft support portion 22 includes, from the tip side to the base end side, a first cylindrical portion 22a having a cylindrical shape, a second cylindrical portion 22b having a cylindrical shape, a third cylindrical portion 22c having a cylindrical shape, a disk-shaped base portion 22d, and a pair of rotationally engaged portions 24 having rotationally engaged portions 24a, 24b (see FIGS. 5 and 6).

[0031] Specifically, as shown in FIG. 5, the first columnar portion 22a has a columnar main body and a protruding portion protruding downward from the main body with approximately the same diameter as the shaft portion 21. The protruding portion is coupled to the shaft portion 21 so as to receive the base end of the shaft portion 21. The second columnar portion 22b has a smaller radial dimension than the first columnar portion 22a so as to have a predetermined gap from the inner circumferential surface of the main body portion 10, and is provided with a rotationally engaged portion 24. The third columnar portion 22c has a smaller radial dimension than the second engaging portion. The first columnar portion 22a, the second columnar portion 22b, and the third columnar portion 22c are integrally formed.

[0032] The base portion 22d has an outer diameter that is approximately the same as that of the first cylindrical portion 22a in the radial direction, and is connected to the third cylindrical portion 22c by a bolt B. As a result, the shaft support portion 22 of the main shaft portion 20 is formed into a shape that fits inside the main body portion 10 by the first cylindrical portion 22a, the second cylindrical portion 22b, the third cylindrical portion 22c, and the base portion 22d, and is supported by the main body support portion 12.

[0033] In addition, the first sliding member 15 and the second sliding member 16 reduce friction with the shaft support portion 22 when the main body portion 10 rotates. In this embodiment, sliding portions are provided at positions corresponding to the first cylindrical portion 22a and the third cylindrical portion 22c. As a result, the main shaft portion 20 is supported rotatably with respect to the main body portion 10.

[0034] 6, the pair of rotationally engaged parts 24 are formed in a sector shape opening at 45° along the circumference of the second cylindrical part 22b, and are arranged to face each other at a distance in the circumferential direction. The main shaft part 20 is fitted to the main body part 10 so that each rotationally engaged part 24 is arranged on both sides between the pair of rotationally engaging parts 14 in the circumferential direction of the main body part 10. This allows the main shaft part 20 to rotate within a predetermined angular range relative to the main body part 10.

[0035] 2, the drilling bit section 30 has a point bit 31 protruding in the second direction Y from the tip of the main shaft section 20, and a pair of main body bits 32 extending in the first direction X from the tip of the main shaft section 20. The pair of main body bits 32 each have a pair of bit extension portions 32a extending in the first direction X and three bit protrusions 32b protruding toward the tip from each bit extension portion 32a.

[0036] The bit protrusions 32b are provided with a predetermined shape and angle so as to excavate soil when the main shaft portion 20 rotates forward (see FIG. 3). That is, the three bit protrusions 32b provided on one bit extension portion 32a and the three bit protrusions 32b provided on the other bit extension portion 32a are formed with an angle so as to protrude in opposite directions.

[0037] The pair of enlarged head support parts 40 are disposed between the drilling bit part 30 and the main body part 10, and are provided opposite to each other with a circumferential gap on the shaft part 21 of the main shaft part 20. Each of the enlarged head support parts 40 has an upper bracket 41, a lower bracket 42, and a column shaft part 43.

[0038] The upper bracket 41 and the lower bracket 42 each have a through hole that supports the column shaft portion 43. The column shaft portion 43 has a cylindrical portion inserted into the through hole of the upper bracket 41 and the through hole of the lower bracket 42, and is fixed by engaging the upper end with the upper bracket 41 and the lower end with the lower bracket 42.

[0039] The enlarged head portion 50 includes a pivot support portion 51 that is passed through the column shaft portion 43 to be rotatable relative to the column shaft portion 43, a pivot bit 52 (the tip of the enlarged head portion 50) extending from the pivot support portion 51, and an enlarged display portion 53 for confirming that the pivot bit 52 is in an expanded diameter state. The upper bracket 41 and the lower bracket 42 of the enlarged head support portion 40 have through holes with a diameter slightly larger than the diameter of the cylindrical portion of the column shaft portion 43, and the column shaft portion 43 is rotatably supported by being attached through the through holes.

[0040] The rotating bit 52 is configured so that its tip faces the opposite direction of rotation during forward rotation so as to be less susceptible to resistance from the soil due to rotation, and is oriented along the circumferential direction of the shaft portion 21 (reduced diameter state) as shown in Fig. 4(B). The rotating bit 52 is configured so that its tip faces the direction of rotation during reverse rotation so as to be less susceptible to resistance from the soil due to rotation, and is oriented so as to extend along the radial direction of rotation (expanded diameter state) as shown in Fig. 4(A). The rotating bit 52 is formed into a shape that allows it to excavate.

[0041] The enlarged display portion 53 allows confirmation that the enlarged head has been enlarged in the ground when the ground improvement device 3 is raised to the ground surface. In this embodiment, the enlarged display portion 53 includes a cylindrical portion extending in the axial direction Y provided on the upper bracket 41 of the enlarged head support portion 40, and a rod-shaped member (not shown) passing through and fixed toward the tip of the cylindrical portion. The cylindrical portion is provided at a position where the rod-shaped member collides with the rotating bit 52 and breaks when the rotating bit 52 is in an enlarged state. By visually checking whether the rod-shaped member of the enlarged display portion 53 raised to the ground surface is broken or not, it can be confirmed whether the enlarged head portion 50 has been enlarged in diameter.

[0042] The expansion bar 60 is formed in a rod shape with roughly rectangular sides, and its center is rotatably supported by the main shaft portion 20. The expansion bar 60 has a length dimension that allows it to engage with both the enlarged head portion 50 and the support protrusion portion 17 of the main body portion 10 when extended along the rotation axis direction Y.

[0043] The support protrusion 17 of the main body 10 is provided on the same side as the side with which the expansion head 50 engages when the expansion bar 60 is aligned along the axial direction Y. When the expansion bar 60 engages with the expansion head 50, the expansion bar 60 engages with the support protrusion 17, so that the expansion bar 60 maintains a position extending along the axial direction Y.

[0044] <Magnifying head operation> In the ground improvement device 3, the main body 10 rotates forward when the rotary drive device 2 rotates forward, and rotates backward when the rotary drive device 2 rotates backward. That is, the main body 10 is connected to the rotary drive device 2 and rotates in synchronization with the rotary drive device 2.

[0045] 6, when the main body 10 rotates forward, one rotation engaged portion 24a of the main body 10 engages with one rotation engaging portion 14a of the main body 10, and the other rotation engaged portion 24b of the main body 10 engages with the other rotation engaging portion 14b of the main body 10, thereby rotating forward. On the other hand, when the main body 10 rotates reversely, one rotation engaged portion 24a of the main shaft 20 engages with the other rotation engaging portion 14b of the main body 10, and the other rotation engaged portion 24b of the main body 10 engages with one rotation engaging portion 14a of the main body 10, thereby rotating reversely.

[0046] Furthermore, when the rotation of the main body 10 switches from forward rotation to reverse rotation, one rotation engaging portion 14a of the main body 10 is released from engagement with one rotation engaged portion 24a of the main shaft 20, and moves toward and engages with the other rotation engaged portion 24b of the main shaft 20. At the same time, the other rotation engaging portion 14b of the main body 10 is released from engagement with the other rotation engaged portion 24b of the main shaft 20, and moves toward and engages with one rotation engaged portion 24a of the main shaft 20. During this period, that is, while the rotation engaging portion 14 moves from being released from engagement with the rotation engaged portion 24 to being newly engaged with the rotation engaged portion 24, the main shaft 20 does not rotate, and only the main body 10 rotates in the reverse direction.

[0047] As shown in FIG. 7, in the ground improvement device 3, when the rotary drive device 2 shifts from forward rotation to reverse rotation, only the main body 10 rotates in the reverse direction, the support protrusion 17 of the main body 10 engages with the other end of the expansion bar 60, and one end of the expansion bar 60 rotates toward the expansion head 50. As a result, one end of the expansion bar 60 engages with the expansion head 50, and the expansion head 50 enters an expanded state. As the expansion head 50 enters an expanded state, the main shaft 20 also begins to rotate in the reverse direction, and the expansion head 50 is reliably expanded under soil pressure. The position of the expansion bar 60 is free due to soil pressure during forward rotation.

[0048] <Modification> In this embodiment, the ground improvement device 3 has been described as being connected to and rotated by the rotary drive device 2. However, the ground improvement device 3 may be one including the rotary drive device 2.

[0049] In this embodiment, the ground improvement device 3 has been described as rotating the main body 10 connected to the rotary drive device 2, and rotating the main shaft portion 20 through the rotation of the main body 10. However, the ground improvement device 3 may also be configured to rotate the main shaft portion 20 through the rotary drive device 2, and rotate the main body portion 10 through the rotation of the main shaft portion 20.

[0050] In this embodiment, the main body portion 10 has been described as including the main body connecting portion 11, the main body supporting portion 12, and the screw portion 13. However, the main body portion 10 may have another configuration as long as it supports the main shaft portion 20 and rotates the main shaft portion 20 in synchronization under predetermined conditions.

[0051] In this embodiment, the main shaft portion 20 has been described as including the shaft portion 21 and the shaft support portion 22. However, the main shaft portion 20 may have another configuration as long as a cutting bit is attached to the main shaft portion 20, the main shaft portion 20 receives the rotational force of a rotary drive device, and rotates to perform cutting.

[0052] In this embodiment, the drilling bit unit 30 is described as having a tip bit 31 and a main bit 32 consisting of a bit extension 32a and three bit protrusions 32b. However, the drilling bit unit 30 may have another configuration as long as it can perform drilling during forward rotation.

[0053] In this embodiment, the enlarged head support part 40 includes an upper bracket 41, a lower bracket 42, and a column shaft part 43, and is provided on the shaft part 21 of the main shaft part 20 so as to face each other with a circumferential gap therebetween. However, the enlarged head support part 40 may have another configuration as long as it can rotatably support the enlarged head part 50.

[0054] In the present embodiment, the expanding head portion 50 has been described as including a rotation support portion 51 that is passed through the column shaft portion 43 so as to be rotatable relative to the column shaft portion 43, and a rotating bit 52 (the tip of the expanding head portion) extending from the rotation support portion 51. However, the expanding head portion 50 may have another configuration as long as the rotating bit can rotate from a reduced diameter state to an expanded diameter state.

[0055] In this embodiment, the expansion bar 60 is described as being pivotally supported on the main shaft portion. However, as long as the expansion bar has the function of putting the enlarged head portion into an expanded diameter state when the rotation drive device 2 switches from forward rotation to reverse rotation, the expansion bar may be attached to the main body portion or may be fixedly attached instead of being pivotally supported.

[0056] In this embodiment, the enlarged display portion is provided with a cylindrical upper portion extending in the axial direction on the upper bracket 41 of the enlarged head support portion 40, and a rod-shaped member (not shown) is passed through the cylindrical portion toward the distal end and fixed thereto. However, the enlarged display portion 53 may have a different configuration as long as it is possible to confirm that the enlarged head has been enlarged in diameter.

[0057] The ground improvement system S according to the embodiment of the present invention has been described above. However, the ground improvement system S is not limited to the above embodiment, and may have other configurations within the scope of achieving the object of the invention. [Industrial Applicability]

[0058] The present invention can be used in civil engineering works such as ground improvement works. [Explanation of symbols]

[0059] 1: Base machine 2: Rotation drive unit 3: Ground improvement equipment 10: Main body 11: Main body connection part 12: Main body support part 13: Screw section 14: Rotation engagement part 14a: Rotational engagement part 14b: Rotational engagement part 15: First sliding member 16: Second sliding member 17: Support protrusion 20: Main shaft part 21: Shaft section 22: Shaft support 22a: First cylindrical section 22b: Second cylindrical section 22c: Third cylindrical section 22d: Base 24: Rotating engaged part 24a: Rotation engaged part 24b: Rotation engaged part 30: Drilling bit section 31: Pointed bit 32: Body bit 32a: Bit extension 32b: Bit protrusion 40: Enlarged head support 41: Upper bracket 42: Lower bracket 43:Column shaft part 50: Enlarged head section 51: Rotation support part 52: Rotating bit 53: Enlarged sign area 60: Expanding bar B: Bolt R: Flow path S: Ground improvement system

Claims

1. a rotating body or spindle connected to a rotary drive; A drilling bit portion provided at the tip of the main shaft portion; A pair of support portions provided on the main shaft portion radially opposed to each other on the base end side of the drilling bit portion; an enlarged head portion pivotally attached to the support portion; a pair of expansion bars provided on the main shaft or the main body above the enlarged head, the expansion bars having a length extending to a lower end of the enlarged head, and engageable with the enlarged head; When the rotary drive device rotates in the forward direction, the main body and the main shaft rotate in the forward direction, and the tip of the enlarged head rotates so that the tip of the enlarged head is aligned in the circumferential direction of the main shaft, When the rotary drive device rotates in the reverse direction, the main body and the main shaft rotate in the reverse direction, and the tip of the enlarged head rotates so that the tip of the enlarged head extends in the radial direction of the main shaft, and the enlargement bar reaches the lower end of the enlarged head and engages with the enlarged head, thereby rotating the tip of the enlarged head, The main body portion includes a main body connecting portion that is connected to the rotation drive device and extends in a rotation axis direction, and a cylindrical main body support portion that is provided below the main body connecting portion and supports the main shaft portion, The main shaft portion is supported by the main body portion and extends in a direction of a rotation axis, A ground improvement device, characterized in that the main body support portion is provided with a first sliding member that contacts and slides against the main shaft portion on an inner peripheral surface of a cylindrical shape, and a second sliding member.

2. The tip of the enlarged head portion is aligned in the radial direction of the main shaft portion. The ground improvement device according to claim 1, further comprising an enlarged display section that allows confirmation of rotation when the device is pulled up to the ground.

3. a rotating body or spindle connected to a rotary drive; A drilling bit portion provided at the tip of the main shaft portion; A pair of support portions provided on the main shaft portion radially opposed to each other on the base end side of the drilling bit portion; an enlarged head portion pivotally attached to the support portion; a pair of expansion bars provided on the main shaft or the main body above the enlarged head, the expansion bars having a length extending to a lower end of the enlarged head, and engageable with the enlarged head; When the rotary drive device rotates in the forward direction, the main body and the main shaft rotate in the forward direction, and the tip of the enlarged head rotates so that the tip of the enlarged head is aligned in the circumferential direction of the main shaft, When the rotary drive device rotates in the reverse direction, the main body and the main shaft rotate in the reverse direction, and the tip of the enlarged head rotates so that the tip of the enlarged head extends in the radial direction of the main shaft, and the enlargement bar reaches the lower end of the enlarged head and engages with the enlarged head, thereby rotating the tip of the enlarged head, The expansion bar is journalled to the main shaft portion, A ground improvement device, characterized in that a tip of the enlarged head portion is rotated by engaging one end with the enlarged head portion and engaging the other end with the support protrusion portion of the main body portion.

4. The main shaft portion is The ground improvement device according to claim 3, wherein when switching from a state in which the main body rotates synchronously with the forward rotation to a state in which the main shaft rotates in reverse, the main body rotates freely for a predetermined angle, and then rotates in reverse again in synchronization with the main shaft.

5. A rotary drive device capable of switching between forward and reverse rotation; A main body or a main shaft portion that is connected to the rotary drive device and rotates; A drilling bit portion provided at the tip of the main shaft portion; A pair of support portions provided on the main shaft portion radially opposed to each other on the base end side of the drilling bit portion; an enlarged head portion pivotally attached to the support portion; a pair of expanding bars provided on the main shaft or the main body above the enlarged head, extending in a rod-like shape to a lower end of the enlarged head, and engageable with the enlarged head; When the rotary drive device rotates in the forward direction, the main body and the main shaft rotate in the forward direction, and the tip of the enlarged head rotates so that the tip of the enlarged head is aligned in the circumferential direction of the main shaft, When the rotary drive device rotates in the reverse direction, the main body and the main shaft rotate in the reverse direction, and the tip of the enlarged head rotates so that the tip of the enlarged head extends in the radial direction of the main shaft, and the enlargement bar reaches the lower end of the enlarged head and engages with the enlarged head, thereby rotating the tip of the enlarged head, The main body portion includes a main body connecting portion that is connected to the rotation drive device and extends in a rotation axis direction, and a cylindrical main body support portion that is provided below the main body connecting portion and supports the main shaft portion, The main shaft portion is supported by the main body portion and extends in a direction of a rotation axis, A ground improvement system, characterized in that the main body support portion is provided with a first sliding member that contacts and slides against the main shaft portion on an inner peripheral surface of a cylindrical shape, and a second sliding member.

6. A rotary drive device capable of switching between forward and reverse rotation; A main body or a main shaft portion that is connected to the rotary drive device and rotates; A drilling bit portion provided at the tip of the main shaft portion; A pair of support portions provided on the main shaft portion radially opposed to each other on the base end side of the drilling bit portion; an enlarged head portion pivotally attached to the support portion; a pair of expanding bars provided on the main shaft or the main body above the enlarged head, extending in a rod-like shape to a lower end of the enlarged head, and engageable with the enlarged head; When the rotary drive device rotates in the forward direction, the main body and the main shaft rotate in the forward direction, and the tip of the enlarged head rotates so that the tip of the enlarged head is aligned in the circumferential direction of the main shaft, When the rotary drive device rotates in the reverse direction, the main body and the main shaft rotate in the reverse direction, and the tip of the enlarged head rotates so that the tip of the enlarged head extends in the radial direction of the main shaft, and the enlargement bar reaches the lower end of the enlarged head and engages with the enlarged head, thereby rotating the tip of the enlarged head, The expansion bar is journalled to the main shaft portion, A ground improvement system, characterized in that the tip of the enlarged head portion is rotated by engaging one end with the enlarged head portion and engaging the other end with the support protrusion portion of the main body portion.

7. Rotating the rotary drive in the forward direction; rotating the main body and the main shaft in a forward direction in synchronization with the rotation drive device; rotating the rotary drive in a reverse direction; Reversely rotating one of the main body portion and the main shaft portion in synchronization with the rotation drive device. After the other of the main body portion or the main shaft portion is rotated by a predetermined angle, the other is rotated in the reverse direction in synchronization with the one of the main body portion or the main shaft portion. When one of the main body and the main shaft rotates in the reverse direction, an expansion bar provided on the upper side of the enlarged head portion rotatably attached to a pair of supports provided on the main shaft portion extends in a rod-like shape to reach the lower end of the enlarged head portion and engage with the enlarged head portion, thereby rotating the tip of the enlarged head portion, The main body portion includes a main body connecting portion that is connected to the rotation drive device and extends in a rotation axis direction, and a cylindrical main body support portion that is provided below the main body connecting portion and supports the main shaft portion, The main shaft portion is supported by the main body portion and extends in a direction of a rotation axis, A method for expanding an improvement area of ​​a ground improvement device, characterized in that the main body support portion is provided with a first sliding member that slides against the main shaft portion in contact with an inner peripheral surface of a cylindrical shape, and a second sliding member.

8. Rotating the rotary drive in the forward direction; rotating the main body and the main shaft in a forward direction in synchronization with the rotation drive device; rotating the rotary drive in a reverse direction; Reversely rotating one of the main body portion and the main shaft portion in synchronization with the rotation drive device. After the other of the main body portion or the main shaft portion is rotated by a predetermined angle, the other is rotated in the reverse direction in synchronization with the one of the main body portion or the main shaft portion. When one of the main body and the main shaft rotates in the reverse direction, an expansion bar provided on the upper side of the enlarged head portion rotatably attached to a pair of supports provided on the main shaft portion extends in a rod-like shape to reach the lower end of the enlarged head portion and engage with the enlarged head portion, thereby rotating the tip of the enlarged head portion, The expansion bar is journalled to the main shaft portion, A method for expanding an improvement area of ​​a ground improvement device, characterized in that the tip of the enlarged head portion is rotated by engaging one end with the enlarged head portion and the other end with the support protrusion portion of the main body portion.

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