JP2013249682A - Ground agitation device and manufacturing method of ground improvement square column body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground agitation device capable of forming a ground improvement square column body underground, in simple configuration, and a manufacturing method of the ground improvement square column body employing the ground agitation device.SOLUTION: A ground agitation device 10 comprises a tubular main body 11, a first blade 18, a pipe member 12, arms 13, 14, second blades 19a, 19b and a drive transmission section. The main body 11 is rotated while supporting the upper end portion thereof. The first blade 18 protrudes in a direction crossing a vertical direction 5 and is rotated together with the main body 11. The pipe member 12 is externally fitted to the main body 11 in a rotatable manner higher than the first blade 18. The arms 13, 14 protrude from the pipe member 12 oppositely in a horizontal direction 6. The second blades 19a, 19b protrude in a direction crossing a length direction of the arms 13, 14, respectively, and are rotated around the length direction of the arms 13, 14. The drive transmission section transmits the rotation of the main body 11 to the second blades 19a, 19b. At least a part of the shape formed by projecting the second blades on a virtual plane orthogonal with the length direction of the main body 11 is located outside of a circle formed by a rotation locus of the first blade 18.

Description

  The present invention relates to a ground agitating device that is used by being penetrated into the ground, and a method for manufacturing a ground-improved prismatic body using the ground agitating device.

If the ground that is the foundation of the structure is soft ground that lacks support and strength, ground reinforcement work is required. A mixed treatment method is known as ground reinforcement work. The mixed treatment method is
This is a construction method in which a cement-based solidifying material slurry is poured into the ground and then stirred and mixed to form a pile-shaped ground improvement body (column) in the ground. As a method of pouring the solidified material into the ground and stirring it, a method of penetrating a bar-shaped ground stirring device into the ground with a heavy machine or the like is known.

  For example, in Patent Document 1, a stirring shaft 10 (ground stirring device) is drilled and penetrated into an improvement target portion of the ground while rotating around an axis, and a second member provided on a tip member of the stirring shaft 10 in the process. A method of injecting a fluidity improver (solidifying agent) from the injection port 16 is disclosed.

  Patent Document 2 discloses a support 1, stirring bodies 4A, 4B, 5A, and 5B that are rotatably attached to the support 1 around a horizontal rotation axis, and a drive source that applies a rotational force to the stirring body. A method using a ground agitator comprising 6A is disclosed.

JP 2011-256541 A JP 2003-342947 A

  In the mixing treatment method using the ground stirring device, the shape and size of the ground improvement body to be formed depend on the ground stirring device. For example, in the invention described in Patent Document 1, since the stirring shaft 10 is rotated around the rotation axis along the vertical direction and stirring is performed, the shape of the ground improvement body formed is approximately circular in plan view. Become.

  In order to form the ground improvement body over a wider section, the above-described series of steps may be performed a plurality of times while shifting the target section where the ground improvement body is formed by one penetration. For example, in the “tangent circle arrangement”, the circular target sections are set adjacent to each other. However, when circles having the same diameter are adjacent to each other, a gap is always interposed, so that the formed ground improvement body is in a state where the portion corresponding to the boundary of the target section is not sufficiently stirred. In order to solve this problem, in the “wrap arrangement”, a part of the target section is overlapped. However, in this case, since the construction is performed a plurality of times for the overlapping sections, the work efficiency is lowered.

  Moreover, in the invention described in Patent Document 2, since the stirring bodies 4A, 4B, 5A, and 5B are rotated by rotating around the horizontal rotation axis, the shape of the ground improvement body to be formed is in a plan view. Expected to be roughly rectangular. Hereinafter, a substantially rectangular ground improvement body in plan view is referred to as a ground improvement prism.

  In such a method, adjacent target sections can be agitated without gaps. However, in the ground stirring device of Patent Document 2, an endless chain 63 and a second endless chain 23 that transmit the driving force of the driving source 6A to the stirring bodies 4A, 4B, 5A, and 5B are provided inside the ground stirring device. Therefore, the structure of the ground stirring device becomes complicated.

  This invention is made | formed in view of the said situation, The objective used the ground stirring apparatus which can form a ground improvement prismatic body in the ground by simple structure, and the said ground stirring apparatus. It is providing the manufacturing method of a ground improvement prismatic body.

  (1) A ground agitating device according to the present invention includes a cylindrical main body that is rotated with its upper end supported, and a first blade that projects in a direction intersecting the longitudinal direction of the main body and rotates integrally with the main body. And a connecting member that is rotatably fitted relative to the main body above the first wing, and in which the arms protrude in opposite directions in a direction orthogonal to the longitudinal direction of the main body. A second wing projecting in a direction intersecting with the longitudinal direction of the arm, and rotating around the longitudinal direction of the arm; and a drive transmission unit for transmitting the rotation of the main body to the second wing. I have. At least a part of the shape obtained by projecting the second wing onto a virtual plane orthogonal to the longitudinal direction of the main body is outside the circle formed by the rotation locus of the first wing.

  When the main body is rotated in a state where the lower end side of the ground agitating device is inserted into the ground, the first wing rotates integrally with the main body to stir the ground. Further, the rotation of the main body is transmitted to the second wing via the drive transmission unit, and the second wing is rotated around an axis substantially along the horizontal direction. Since a part of the shape formed by projecting the second wing onto a virtual plane perpendicular to the longitudinal direction of the main body is outside the circle formed by the rotation trajectory of the first wing, the two second wings are Stir both sides of a circular area where one blade can stir. As a result, the section stirred by the first wing and the two second wings is substantially rectangular in plan view. That is, a ground improvement prismatic body can be formed in the ground.

  (2) The connection member includes a cylindrical member that is positioned with respect to the longitudinal direction of the main body and is externally fitted to the main body, and the arm protrudes to the outside of the cylindrical material. May be.

  In this configuration, a structure for rotating the second blade is easily realized.

  (3) The main body includes a cylindrical first member having an opening at a lower end, and a cylindrical second member provided with the first wing and inserted into the opening of the first member. And the said cylinder material may be arrange | positioned in the connection location of the said 1st member and the said 2nd member.

  In this configuration, the main body is composed of the first member and the second member, whereby assembly of the ground agitating device is facilitated. Moreover, it becomes possible to transfer the ground agitating device in a state where the main body is separated, and to assemble immediately before construction.

  (4) The distance between the tips of the two second wings along the longitudinal direction of the arm and the maximum diameter of the second wing may be greater than or equal to the maximum diameter of the first wing.

  (5) You may have the flow path through which the solidification agent inject | poured into the ground is distribute | circulated and discharged along the longitudinal direction of the said main body.

  In this configuration, the solidifying agent can be distributed along the longitudinal direction of the main body.

  (6) The present invention provides a method for producing a ground-improved prismatic body that forms a ground-improved prismatic body in the ground using the above-described ground agitating device and a penetration device capable of rotationally press-fitting the ground agitating device into the ground. Can also be taken as. The manufacturing method of the ground improved prismatic body according to the present invention includes a penetration step of press-fitting the ground stirring device into the ground while the main body is supported by the penetration device and rotating, and the first blade that is penetrated into the ground. Or a solidifying agent mixing step of rotating the first blade and the second blade while discharging the solidifying agent in the vicinity of the second blade, and the penetration step and the solidifying agent mixing step are It is constructed several times adjacent to the target section where the body is to be formed.

  Since the ground improvement prismatic body manufactured by such a method sufficiently stirs the portion corresponding to the boundary of the target section, the supporting force is improved.

  According to the ground stirring device and the method for producing a ground improved prism according to the present invention, the ground improved prism can be formed in the ground by the ground stirring device having a simple configuration.

FIG. 1 shows a ground stirring device 10 according to an embodiment of the present invention. (A) is a front view, (B) is a right side view. FIG. 2 is an exploded front view of the ground stirring device 10. FIG. 3 is a view showing a combined body of the arm 13, the bevel gear 16, and the second blade 19a. (A) is a plan view, (B) is a front view, and (C) is a left side view. FIG. 4 is a schematic diagram showing how the ground stirring device 10 is penetrated into the ground 42 by the penetration device 38. (A) shows a state immediately before penetration, and (B) shows a state where penetration has been completed. (C) has shown the state by which the pipe body 47 was joined after penetration was completed and the ground stirring apparatus 10 penetrated to the deep part of the ground 42 further (refer modification 2). FIG. 5 (A) shows a state in which construction is performed on an adjacent section by “circular contact arrangement” using a conventional ground stirring device. FIG. 5 (B) shows a state in which construction has been performed on adjacent sections using the ground stirring device 10. The stirring region E1 is a region where stirring is sufficiently performed, and the non-stirring region E2 is a region where stirring is insufficient. FIG. 6 shows a ground stirring device 10 according to Modification 1 of the embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. Note that the embodiment described below is merely an example of the present invention, and it is needless to say that the embodiment of the present invention can be changed as appropriate without departing from the gist of the present invention.

[Outline of ground stirring device 10]
The ground agitation device 10 shown in FIG. 1 is used by being rotationally press-fitted into the ground (hereinafter simply referred to as penetration) using a dedicated penetration device 38 (FIG. 4). The ground agitating device 10 includes a main body 11, a cylindrical member 12, arms 13, 14, bevel gears 15, 16, 17, a first blade 18, second blades 19a, 19b, auxiliary blades 37a, 37b, and the like. The 1st wing | blade 18 plays the role which excavates a ground, when the ground stirring apparatus 10 penetrates into the ground. In the ground, the solidified material is discharged into the ground from a plurality of discharge holes (not shown) formed in the ground stirring device 10. The first wing 18 and the second wings 19a and 19b stir and mix the solidified material and the soil and sand constituting the ground. The solidified material is solidified in the ground, and a ground improved prism is formed. Hereinafter, each part which comprises the ground stirring apparatus 10 is demonstrated in detail. In each figure, a vertical direction 5 is defined with reference to the vertical direction, a first horizontal direction 6 orthogonal to the vertical direction 5 is defined, and a second horizontal direction 7 orthogonal to the vertical direction 5 and the first horizontal direction 6 is defined. Is defined.

[Main unit 11]
The main body 11 shown in FIGS. 1 and 2 is joined to a substantially cylindrical cylindrical member 21 (an example of the first member of the present invention) and a lower side of the cylindrical member 21 (an example of the second member of the present invention). And a cylindrical tip member 22 integrated with the cylindrical member 21. The cylindrical member 21 is a steel pipe having a circular cross section perpendicular to the vertical direction 5. Although not shown in the drawing, the cylindrical member 21 is hollow with an internal space. Openings 23 and 24 (FIG. 2) communicating with the internal space are formed at both ends in the longitudinal direction (up and down direction 5). The total length of the cylindrical member 21 is appropriately determined according to the depth at which the ground stirring device 10 is penetrated.

  A bevel gear 15 (an example of a drive transmission unit of the present invention) is fitted around the lower end of the cylindrical member 21 so as to be integrated with the cylindrical member 21. The bevel gear 15 has a tapered shape with a smaller outer diameter toward the lower end side. Although the details will be described later, the bevel gear 15 is engaged with the bevel gears 16 and 17 to transmit the rotational driving force of the main body 11 to the tubular material 12 to the arms 13 and 14.

  Similar to the cylindrical member 21, the tip member 22 is a steel pipe having a circular cross section perpendicular to the vertical direction 5, and has an internal space. A conical perforated portion 43 is formed at the lower end of the tip member 22. The perforating part 43 is pierced into the ground prior to the penetration of the ground agitating device 10 and reduces the resistance received by the ground agitating device 10 from the ground. A locking plate 32 that protrudes in the radial direction is provided substantially at the center of the tip member 22 in the vertical direction 5. The upper side of the locking plate 32 is referred to as the insertion portion 25 (FIG. 2).

  The outer diameter of the insertion portion 25 is slightly smaller than the opening 24. The insertion portion 25 is inserted into an opening 26 (FIG. 2) below the tubular material 12 described later and penetrates the tubular material 12. The insertion portion 25 that has come out from the upper opening 27 (FIG. 2) is inserted into the opening 24 of the cylindrical member 21. The cylindrical member 21 and the insertion portion 25 are fixed and integrated with a bolt or the like to constitute the main body 11. In this state, the cylindrical member 21 and the tip member 22 are rotatable relative to the tubular material 12. That is, the tubular member 12 is rotatably fitted to the main body 11 at a connection portion between the cylindrical member 21 and the tip member 22. On the other hand, the cylinder member 12 is prevented from moving in the vertical direction 5 with respect to the main body 11. Specifically, the downward movement is blocked by the locking plate 32, and the upward movement is blocked by the bevel gear 15.

  The internal space of the main body 11, the cylinder member 12, and the arms 13 and 14 are in communication with each other. In this internal space, the ground agitating device 10 is formed with a flow path (not shown) for supplying the solidifying agent introduced from the opening 23 of the main body 11 to each discharge hole. A slit 46 (FIG. 2) is formed on the side surface of the cylindrical member 21 so that the internal space of the main body 11 communicates with the internal space of the cylindrical member 12.

[Cylinder 12]
1 and 2 has an internal space, and openings 26, 27, 44, and 45 communicating with the internal space are formed. As described above, the insertion portion 25 is inserted into the cylindrical member 12 through the openings 26 and 27. The inner diameters of the openings 26 and 27 are slightly larger than the outer diameter of the insertion portion 25 so as to rotatably support the insertion portion 25. Further, ball bearings or the like that reduce the rotational resistance of the insertion portion 25 may be provided on the periphery of the openings 26 and 27. The external appearance of the cylindrical member 12 can be appropriately changed as long as it has openings 26 and 27 and supports the insertion portion 25 in a rotatable manner. For example, the tubular member 12 may be generally box-shaped or cylindrical.

  Cylindrical fixed shafts 28 and 29 (FIG. 2) protrude from the cylindrical member 12 in the first horizontal direction 6 in the facing direction. The fixed shafts 28 and 29 are inserted into the openings 30 and 31 (FIG. 2) of the arms 13 and 14, respectively, and rotatably support the arms 13 and 14. The openings 44 and 45 described above are formed at the tips of the fixed shafts 28 and 29, respectively. The openings 44 and 45 communicate the internal space of the tubular member 12 with the internal spaces of the arms 13 and 14.

[Arms 13, 14]
The arms 13 and 14 shown in FIGS. 1 and 2 have a generally cylindrical appearance in which openings 30 and 31 are formed on one end side. The inner diameters of the openings 30 and 31 are slightly larger than the outer diameters of the fixed shafts 28 and 29 so as to rotatably support the fixed shafts 28 and 29. Further, ball bearings or the like for reducing the rotational resistance of the fixed shafts 28 and 29 may be provided at the peripheral edges of the openings 30 and 31. The fixed shaft 28 is inserted into the opening 30 of the arm 13, and the fixed shaft 29 is inserted into the opening 31 of the arm 14. The fixed shafts 28 and 29 are arranged so that the central axes coincide with each other.

  After being inserted into the openings 30 and 31, a retaining member (not shown) for retaining is attached to the tips of the fixed shafts 28 and 29. This locking member is locked in the first horizontal direction 6 inside the arms 13 and 14, and the fixed shafts 28 and 29 are prevented from coming out of the openings 30 and 31. Although the thing of arbitrary shapes is used for a locking member, it is a ring shape as an example. However, the fixing shafts 28 and 29 may be provided with a means for preventing the slippage different from this.

  Bevel gears 16 and 17 are fitted around the ends of the arms 13 and 14 on the cylindrical member 12 side. The bevel gears 16 and 17 have the same tapered shape as the bevel gear 15. The bevel gears 16 and 17 mesh with the bevel gear 15, respectively. Second wings 19a and 19b, which will be described later, are formed on the other ends of the arms 13 and 14, respectively.

[First wing 18]
The first wing 18 shown in FIGS. 1 and 2 is provided around the lower end portion of the main body 11, specifically, above the perforated portion 43 in the tip member 22. The first blade 18 is composed of two elongated steel plates that protrude in opposite directions perpendicular to the vertical direction 5. The steel plates are inclined and curved in the same direction as viewed from the outer peripheral side.

  When the first wing 18 is in contact with the ground and rotated in a predetermined direction (clockwise as viewed from above in the present embodiment) while the main body 11 is pressed downward, the first wing 18 moves over the ground surface. After excavation, the ground stirring device 10 is penetrated into the ground. In addition, after the first blade 18 is buried in the ground, the first blade 18 functions as a screw, and generates a downward propulsive force that penetrates the ground stirring device 10 into the ground. Further, after the solidified material is discharged from the discharge hole, the solidified material and the soil and sand constituting the ground are agitated and mixed by the rotation of the first blade 18.

  Although the 1st wing | blade 18 is attached to the front-end | tip member 22 by arbitrary methods, for example, after inserting in the slit (not shown) formed in the side surface of the front-end | tip member 22, you may be fixed by welding etc.

  However, the shape of the first blade 18 described above is merely an example. If the 1st wing | blade 18 excavates the ground and stirs and mixes the solidification material and the soil and sand which comprise the ground, you may be comprised in the shape different from the thing of this embodiment.

[Second wing 19a, 19b]
Second wings 19a and 19b shown in FIGS. 1, 2 and 3 are formed at the ends of arms 13 and 14 opposite to the openings 30 and 31, respectively. FIG. 3 shows only the second wing 19a, but the second wings 19a and 19b are configured in the same shape.

  The second wings 19a and 19b are constituted by two substantially T-shaped steel plates that protrude from the arms 13 and 14 in opposite directions perpendicular to the first horizontal direction 6, respectively. That is, the second blades 19a and 19b are configured by a total of four steel plates. In this steel plate, a portion corresponding to a vertical line of the alphabet “T” is referred to as a protruding portion 34, and a portion corresponding to a horizontal line is referred to as a developed portion 35. The tips of the protrusions 34 are connected to the arms 13 and 14, respectively. As shown in FIG. 3A, the projecting portions 34 facing each other via the arms 13 and 14 are twisted in directions opposite to each other. Therefore, as shown in FIG. 3C, the two expanded portions 35 intersect each other when viewed from the longitudinal direction of the protruding portion 34. This shape is for the second blades 19a and 19b to efficiently agitate and mix the ground.

  The outer peripheral surface of the development part 35 is formed in a curved surface shape. A plurality of barbs 36 are projected along the outer peripheral surface of the deployment part 35. The tip of the spine 36 is pointed and has a shape that makes it easy to pulverize the hard soil that constitutes the ground.

  The distance L2 (FIG. 1A) between the tips of the two second blades 19a and 19b is longer than the maximum diameter L1 of the first blade 18 (FIG. 1B). Further, the maximum diameter L3 (FIG. 1B) of the second blades 19a and 19b is longer than L1. That is, when viewed from the vertical direction 5, a part of the second wings 19 a and 19 b is outside the circle formed by the rotation trajectory of the first wing 18.

  In such a configuration, the second blades 19a and 19b can stir and mix up to regions outside the first horizontal direction 6 and the first horizontal direction 7 from the region where the first blade 18 can stir the ground. It is. The section agitated and mixed by the first blade 18 and the second blades 19a and 19b has a generally rectangular shape of L2 × L3 when viewed from the vertical direction 5. However, L2 and L3 may be the same length as L1 at the shortest.

[Auxiliary wings 37a, 37b]
Further, auxiliary wings 37a and 37b for assisting the stirring and mixing of the ground are provided on the side surfaces of the cylindrical member 21 and the tip member 22, respectively. The auxiliary wing 37 a of the cylindrical member 21 is provided on the upper side of the bevel gear 15, and the auxiliary wing 37 b of the tip member 22 is provided on the lower side of the locking plate 32. The auxiliary wings 37a and 37b are elongated plates that protrude from the side surfaces of the cylindrical member 21 and the tip member 22, respectively. The auxiliary wings 37a and 37b are 90 ° out of phase in the circumferential direction, and the cylindrical member 21 And four pieces are arranged for each tip member 22. The auxiliary blades 37a and 37b are inclined in the same direction as the first blade 18 as viewed from the outside. The length of the auxiliary blade 37 in the radial direction (longitudinal direction) is shorter than that of the first blade 18 and is long enough not to interfere with the second blades 19a and 19b.

[Penetration device 38]
The penetration device 38 shown in FIG. 4 is used to penetrate the ground stirring device 10 into the ground. Since the penetration device 38 is known, an example of its configuration will be briefly described. The penetration device 38 according to the present embodiment includes a support column 39, an auger 40 attached to the support column 39, a vehicle body 41, and the like.

  The auger 40 supports the upper end of the main body 11 and generates torque for rotation. In addition, the auger 40 can move in the vertical direction 5 along the support column 39 in a state where torque is applied to the main body 11. Driving force is transmitted from different motors (not shown) for rotation of the main body 11 and vertical movement of the auger 40. When the auger 40 moves downward with the main body 11 supported, the ground stirring device 10 is pressed against the ground. In this state, the ground stirring device 10 penetrates into the ground by rotating the main body 11.

  The support column 39 is supported by an arbitrary method, but is attached to and supported by the vehicle body 41 in the present embodiment. The vehicle body 41 is a heavy machine, and the auger 40 can be operated from the cockpit.

  However, as long as the penetration device 38 penetrates the ground agitating device 10 into the ground, a different structure may be used. For example, the penetrating device 38 is not necessarily integrated with the vehicle body 41.

[Formation of ground improved prisms]
Hereinafter, a method of forming the ground improved prismatic body in the ground using the ground stirring device 10 and the penetration device 38 described above will be described. As shown in FIG. 4A, the ground stirring device 10 is placed on the ground 42 of the target section. The perforated part 43 is pierced into the ground 42 and the ground stirring device 10 is self-supporting. In this state, the upper end portion of the main body 11 is supported by the auger 40.

  A force that moves downward acts on the auger 40, and at the same time, torque is applied to the main body 11. The direction of the torque is the direction in which the first blade 18 produces a downward driving force (clockwise as viewed from above in the present embodiment).

  In a state where the lower end portion of the ground stirring device 10 is buried in the ground 42, the arms 13 and 14 receive resistance from the ground 42. Thereby, the cylinder 12 does not rotate integrally with the main body 11, and the main body 11 rotates relative to the cylinder 12. The rotation of the main body 11 is transmitted to the arms 13 and 14 via the bevel gears 15, 16 and 17. As a result, the second blades 19a and 19b rotate integrally with the arms 13 and 14.

  In the process in which the ground agitating device 10 is inserted, the first blade 18 excavates the ground 42 in advance, and the second blades 19a and 19b and the auxiliary blades 37a and 37b further agitate the region excavated by the first blade 18. To do. At the same time, the second wings 19 a and 19 b excavate a region further outside the region excavated by the first wing 18. The process of penetrating the ground stirring device 10 into the ground 42 is an example of the penetrating process of the present invention.

  After the ground agitation device 10 has penetrated to the target depth (the state in FIG. 4B), the direction of the torque applied to the main body 11 is reversed. As a result, the rotation of the main body 11 is reversed, and the first blade 18 generates an upward driving force. At the same time, an upward force is applied to the auger 40, and the ground agitating device 10 is raised.

  The solidifying agent is poured into the flow path inside the ground agitator 10 while repeating the ascent and descent of the ground agitator 10. As the solidifying agent, a cement-based one is generally used. After passing through the flow path, the solidifying agent is discharged into the ground from each discharge hole. The solidifying agent may be supplied from the penetration device 38 to the ground agitation device 10 or may be supplied from different equipment to the ground agitation device 10 via a tube or the like. The first wing 18, the second wings 19a and 19b, and the auxiliary wings 37a and 37b stir and mix the soil and sand constituting the ground 42 and the solidifying agent. This step is an example of the solidifying agent mixing step of the present invention.

  After the agitation and mixing are sufficiently performed, the ground agitating device 10 is raised and removed from the ground 42. Thereafter, the solidifying agent remaining in the ground is solidified, so that a substantially rectangular parallelepiped ground improved prism is formed in the ground. This ground improvement prismatic body is substantially rectangular of L2 × L3 when viewed from the vertical direction 5. Moreover, the ground improvement prismatic body is formed from the ground surface to the deepest part where the 1st wing | blade 18 penetrated.

  If necessary, the ground-improved prismatic body can be formed in a wider section by executing the above-described series of steps a plurality of times while shifting the target section that penetrates the ground stirring device 10.

[Operational effects of this embodiment]
In the ground stirring device 10 according to the present embodiment, the ground improved prismatic body can be formed in a generally rectangular section of L2 × L3 in plan view. Thereby, a ground improvement prismatic body can be formed in a rectangular adjacent section without a gap.

  Details will be described below. In the conventional configuration not including the second wings 19a and 19b, the ground improvement body is formed in a substantially circular section by a single construction. Therefore, when the construction is performed a plurality of times by the “circular contact arrangement”, as shown in FIG. 5A, the non-stirring region E2 with insufficient stirring is formed in the gap between the stirring regions E1 where stirring is performed. It is formed.

  On the other hand, in the ground agitation device 10 according to the present embodiment, since the ground improvement prismatic body is formed in the L2 × L3 section by one construction, as shown in FIG. E1 can be arranged adjacent to each other without a gap. Thereby, the supporting force of the ground improvement prism body formed as a whole improves rather than the conventional ground improvement body. In FIG. 5B, an example of L2 = L3 is shown.

  Further, in the ground agitation device 10 according to the present embodiment, the rotation of the main body 11 is transmitted to the second blades 19a and 19b via the bevel gears 15, 16, and 17, so that the second blades 19a and 19b are rotated. The configuration is easily realized and the configuration of the penetrating device 38 is simplified. That is, as the penetration device 38, a known device that simply penetrates the ground stirring device 10 into the ground can be used.

  Moreover, since the main body 11 is comprised from the cylindrical member 21 and the front-end | tip member 22, the assembly of the ground stirring apparatus 10 is easy. In particular, it is possible to transfer the ground stirring device 10 in a disassembled state and immediately assemble it before construction.

  Further, the bevel gear 15 and the locking plate 32 prevent the cylindrical member 12 from moving in the vertical direction 5.

[Modification 1]
As shown in FIG. 6, a housing 48 that accommodates the bevel gears 15, 16, and 17 may be used instead of the tubular member 12. The point that the housing 48 is rotatably fitted to the main body 11 and the point that the housing 48 rotatably supports the arms 13 and 14 are the same as those of the cylindrical member 12 described above. In FIG. 6, the housing 48 is shown in a cubic shape, but the shape can be changed as appropriate.

[Modification 2]
Moreover, when the length of the ground stirring apparatus 10 is insufficient to reach the first wing 18 and the second wings 19 a and 19 b to the target depth, the pipe body 47 may be joined to the main body 11.

  In detail, after penetrating the ground agitating device 10 until the upper end of the main body 11 is located near the ground surface (state of FIG. 4B), the pipe body 47 is joined to the upper end of the main body 11. The tubular body 47 has a cylindrical shape similar to that of the cylindrical member 21. For joining the pipe bodies 47, a technique such as welding may be used, or a dedicated joint may be used. Subsequently, the auger 40 is connected to the upper end of the tubular body 47, and the ground agitating device 10 integrated with the tubular body 47 is penetrated into the deeper portion of the ground 42 (state shown in FIG. 4C).

[Modification 3]
The number and shape of the first wing 18 and the second wings 19a and 19b described above are merely examples, and can be appropriately changed by those skilled in the art. For example, a total of four first blades 18 and second blades 19a and 19b may be projected with a phase shift of 90 ° in the circumferential direction. Moreover, the 1st blade | wing 18 may be comprised, for example in the spiral shape.

[Modification 4]
In order to transmit the rotation of the main body 11 to the second wings 19a and 19b, a method different from the above-described embodiment may be used. For example, the arms 13 and 14 do not need to rotate integrally with the second wings 19a and 19b, and may support the second wings 19a and 19b rotatably. The rotational driving force for the second wings 19a and 19b may be transmitted to the second wings 19a and 19b via, for example, a rotation shaft provided inside the arms 13 and 14.

[Modification 5]
In the above-described embodiment, the flow path and the discharge hole formed in the ground stirring device 10 are used to flow the solidifying agent into the ground, but the solidifying agent may be supplied to the ground in a different manner. Good. For example, the flow path may be a tube or a slit provided outside the main body 11. Alternatively, the solidifying agent may be poured into the ground by a device independent of the ground stirring device 10.

10 ... Ground stirring device 11 ... Body 15, 16, 17 ... Bevel gear (drive transmission unit)
18 ... 1st wing | blade 19a, 19b ... 2nd wing | blade 12 ... cylinder material (connection member)
13, 14 ... Arm (connection member)
21 ... Cylindrical member (first member)
22 ... Tip member (second member)
38 ... Penetration device 42 ... Ground 47 ... Tube

  The present invention relates to a ground agitating device that is used by being penetrated into the ground, and a method for manufacturing a ground-improved prismatic body using the ground agitating device.

If the ground that is the foundation of the structure is soft ground that lacks support and strength, ground reinforcement work is required. A mixed treatment method is known as ground reinforcement work. The mixed processing method is
This is a construction method in which a cement-based solidifying material slurry is poured into the ground and then stirred and mixed to form a pile-shaped ground improvement body (column) in the ground. As a method of pouring the solidified material into the ground and stirring it, a method of penetrating a bar-shaped ground stirring device into the ground with a heavy machine or the like is known.

  For example, in Patent Document 1, a stirring shaft 10 (ground stirring device) is drilled and penetrated into an improvement target portion of the ground while rotating around an axis, and a second member provided on a tip member of the stirring shaft 10 in the process. A method of injecting a fluidity improver (solidifying agent) from the injection port 16 is disclosed.

  Patent Document 2 discloses a support 1, stirring bodies 4A, 4B, 5A, and 5B that are rotatably attached to the support 1 around a horizontal rotation axis, and a drive source that applies a rotational force to the stirring body. A method using a ground agitator comprising 6A is disclosed.

JP 2011-256541 A JP 2003-342947 A

  In the mixing treatment method using the ground stirring device, the shape and size of the ground improvement body to be formed depend on the ground stirring device. For example, in the invention described in Patent Document 1, since the stirring shaft 10 is rotated around the rotation axis along the vertical direction and stirring is performed, the shape of the ground improvement body formed is approximately circular in plan view. Become.

  In order to form the ground improvement body over a wider section, the above-described series of steps may be performed a plurality of times while shifting the target section where the ground improvement body is formed by one penetration. For example, in the “tangent circle arrangement”, the circular target sections are set adjacent to each other. However, when circles having the same diameter are adjacent to each other, a gap is always interposed, so that the formed ground improvement body is in a state where the portion corresponding to the boundary of the target section is not sufficiently stirred. In order to solve this problem, in the “wrap arrangement”, a part of the target section is overlapped. However, in this case, since the construction is performed a plurality of times for the overlapping sections, the work efficiency is lowered.

  Moreover, in the invention described in Patent Document 2, since the stirring bodies 4A, 4B, 5A, and 5B are rotated by rotating around the horizontal rotation axis, the shape of the ground improvement body to be formed is in a plan view. Expected to be roughly rectangular. Hereinafter, a substantially rectangular ground improvement body in plan view is referred to as a ground improvement prism.

  In such a method, adjacent target sections can be agitated without gaps. However, in the ground stirring device of Patent Document 2, an endless chain 63 and a second endless chain 23 that transmit the driving force of the driving source 6A to the stirring bodies 4A, 4B, 5A, and 5B are provided inside the ground stirring device. Therefore, the structure of the ground stirring device becomes complicated.

  This invention is made | formed in view of the said situation, The objective used the ground stirring apparatus which can form a ground improvement prismatic body in the ground by simple structure, and the said ground stirring apparatus. It is providing the manufacturing method of a ground improvement prismatic body.

(1) A ground agitating device according to the present invention includes a cylindrical main body that is rotated with its upper end supported, and a first blade that projects in a direction intersecting the longitudinal direction of the main body and rotates integrally with the main body. And a connecting member that is rotatably fitted relative to the main body above the first wing, and in which the arms protrude in opposite directions in a direction orthogonal to the longitudinal direction of the main body. A second wing projecting in a direction intersecting with the longitudinal direction of the arm, and rotating around the longitudinal direction of the arm; and a drive transmission unit for transmitting the rotation of the main body to the second wing. I have. At least a part of the shape obtained by projecting the second wing onto a virtual plane orthogonal to the longitudinal direction of the main body is outside the circle formed by the rotation locus of the first wing. The main body and the arm each have a flow path through which a solidifying agent injected into the ground is circulated and discharged along the longitudinal direction, and each flow path is communicated in the internal space of the connection member.

When the main body is rotated in a state where the lower end side of the ground agitating device is inserted into the ground, the first wing rotates integrally with the main body to stir the ground. Further, the rotation of the main body is transmitted to the second wing via the drive transmission unit, and the second wing is rotated around an axis substantially along the horizontal direction. Since a part of the shape formed by projecting the second wing onto a virtual plane perpendicular to the longitudinal direction of the main body is outside the circle formed by the rotation trajectory of the first wing, the two second wings are Stir both sides of a circular area where one blade can stir. As a result, the section stirred by the first wing and the two second wings is substantially rectangular in plan view. That is, a ground improvement prismatic body can be formed in the ground. Moreover, a necessary solidifying agent can be distributed along the flow path.

  (2) The connection member includes a cylindrical member that is positioned with respect to the longitudinal direction of the main body and is externally fitted to the main body, and the arm protrudes to the outside of the cylindrical material. May be.

  In this configuration, a structure for rotating the second blade is easily realized.

  (3) The main body includes a cylindrical first member having an opening at a lower end, and a cylindrical second member provided with the first wing and inserted into the opening of the first member. And the said cylinder material may be arrange | positioned in the connection location of the said 1st member and the said 2nd member.

  In this configuration, the main body is composed of the first member and the second member, whereby assembly of the ground agitating device is facilitated. Moreover, it becomes possible to transfer the ground agitating device in a state where the main body is separated, and to assemble immediately before construction.

  (4) The distance between the tips of the two second wings along the longitudinal direction of the arm and the maximum diameter of the second wing may be greater than or equal to the maximum diameter of the first wing.

(5) The present invention provides a method for producing a ground-improved prismatic body that forms a ground-improved prismatic body in the ground using the above-described ground agitating device and a penetration device capable of rotationally press-fitting the ground agitating device into the ground. Can also be taken as. The manufacturing method of the ground improved prismatic body according to the present invention includes a penetration step of press-fitting the ground stirring device into the ground while the main body is supported by the penetration device and rotating, and the first blade that is penetrated into the ground. Or a solidifying agent mixing step of rotating the first blade and the second blade while discharging the solidifying agent through the flow path in the vicinity of the second blade, and the penetration step and the solidifying agent The mixing process is performed a plurality of times adjacent to the target section where the ground improvement prismatic body is to be formed.

  Since the ground improvement prismatic body manufactured by such a method sufficiently stirs the portion corresponding to the boundary of the target section, the supporting force is improved.

  According to the ground stirring device and the method for producing a ground improved prism according to the present invention, the ground improved prism can be formed in the ground by the ground stirring device having a simple configuration.

FIG. 1 shows a ground stirring device 10 according to an embodiment of the present invention. (A) is a front view, (B) is a right side view. FIG. 2 is an exploded front view of the ground stirring device 10. FIG. 3 is a view showing a combined body of the arm 13, the bevel gear 16, and the second blade 19a. (A) is a plan view, (B) is a front view, and (C) is a left side view. FIG. 4 is a schematic diagram showing how the ground stirring device 10 is penetrated into the ground 42 by the penetration device 38. (A) shows a state immediately before penetration, and (B) shows a state where penetration has been completed. (C) has shown the state by which the pipe body 47 was joined after penetration was completed and the ground stirring apparatus 10 penetrated to the deep part of the ground 42 further (refer modification 2). FIG. 5 (A) shows a state in which construction is performed on an adjacent section by “circular contact arrangement” using a conventional ground stirring device. FIG. 5 (B) shows a state in which construction has been performed on adjacent sections using the ground stirring device 10. The stirring region E1 is a region where stirring is sufficiently performed, and the non-stirring region E2 is a region where stirring is insufficient. FIG. 6 shows a ground stirring device 10 according to Modification 1 of the embodiment.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. Note that the embodiment described below is merely an example of the present invention, and it is needless to say that the embodiment of the present invention can be changed as appropriate without departing from the gist of the present invention.

[Outline of ground stirring device 10]
The ground agitation device 10 shown in FIG. 1 is used by being rotationally press-fitted into the ground (hereinafter simply referred to as penetration) using a dedicated penetration device 38 (FIG. 4). The ground agitating device 10 includes a main body 11, a cylindrical member 12, arms 13, 14, bevel gears 15, 16, 17, a first blade 18, second blades 19a, 19b, auxiliary blades 37a, 37b, and the like. The 1st wing | blade 18 plays the role which excavates a ground, when the ground stirring apparatus 10 penetrates into the ground. In the ground, the solidified material is discharged into the ground from a plurality of discharge holes (not shown) formed in the ground stirring device 10. The first wing 18 and the second wings 19a and 19b stir and mix the solidified material and the soil and sand constituting the ground. The solidified material is solidified in the ground, and a ground improved prism is formed. Hereinafter, each part which comprises the ground stirring apparatus 10 is demonstrated in detail. In each figure, a vertical direction 5 is defined with reference to the vertical direction, a first horizontal direction 6 orthogonal to the vertical direction 5 is defined, and a second horizontal direction 7 orthogonal to the vertical direction 5 and the first horizontal direction 6 is defined. Is defined.

[Main unit 11]
The main body 11 shown in FIGS. 1 and 2 is joined to a substantially cylindrical cylindrical member 21 (an example of the first member of the present invention) and a lower side of the cylindrical member 21 (an example of the second member of the present invention). And a cylindrical tip member 22 integrated with the cylindrical member 21. The cylindrical member 21 is a steel pipe having a circular cross section perpendicular to the vertical direction 5. Although not shown in the drawing, the cylindrical member 21 is hollow with an internal space. Openings 23 and 24 (FIG. 2) communicating with the internal space are formed at both ends in the longitudinal direction (up and down direction 5). The total length of the cylindrical member 21 is appropriately determined according to the depth at which the ground stirring device 10 is penetrated.

  A bevel gear 15 (an example of a drive transmission unit of the present invention) is fitted around the lower end of the cylindrical member 21 so as to be integrated with the cylindrical member 21. The bevel gear 15 has a tapered shape with a smaller outer diameter toward the lower end side. Although the details will be described later, the bevel gear 15 is engaged with the bevel gears 16 and 17 to transmit the rotational driving force of the main body 11 to the tubular material 12 to the arms 13 and 14.

  Similar to the cylindrical member 21, the tip member 22 is a steel pipe having a circular cross section perpendicular to the vertical direction 5, and has an internal space. A conical perforated portion 43 is formed at the lower end of the tip member 22. The perforating part 43 is pierced into the ground prior to the penetration of the ground agitating device 10 and reduces the resistance received by the ground agitating device 10 from the ground. A locking plate 32 that protrudes in the radial direction is provided substantially at the center of the tip member 22 in the vertical direction 5. The upper side of the locking plate 32 is referred to as the insertion portion 25 (FIG. 2).

  The outer diameter of the insertion portion 25 is slightly smaller than the opening 24. The insertion portion 25 is inserted into an opening 26 (FIG. 2) below the tubular material 12 described later and penetrates the tubular material 12. The insertion portion 25 that has come out from the upper opening 27 (FIG. 2) is inserted into the opening 24 of the cylindrical member 21. The cylindrical member 21 and the insertion portion 25 are fixed and integrated with a bolt or the like to constitute the main body 11. In this state, the cylindrical member 21 and the tip member 22 are rotatable relative to the tubular material 12. That is, the tubular member 12 is rotatably fitted to the main body 11 at a connection portion between the cylindrical member 21 and the tip member 22. On the other hand, the cylinder member 12 is prevented from moving in the vertical direction 5 with respect to the main body 11. Specifically, the downward movement is blocked by the locking plate 32, and the upward movement is blocked by the bevel gear 15.

  The internal space of the main body 11, the cylinder member 12, and the arms 13 and 14 are in communication with each other. In this internal space, the ground agitating device 10 is formed with a flow path (not shown) for supplying the solidifying agent introduced from the opening 23 of the main body 11 to each discharge hole. A slit 46 (FIG. 2) is formed on the side surface of the cylindrical member 21 so that the internal space of the main body 11 communicates with the internal space of the cylindrical member 12.

[Cylinder 12]
1 and 2 has an internal space, and openings 26, 27, 44, and 45 communicating with the internal space are formed. As described above, the insertion portion 25 is inserted into the cylindrical member 12 through the openings 26 and 27. The inner diameters of the openings 26 and 27 are slightly larger than the outer diameter of the insertion portion 25 so as to rotatably support the insertion portion 25. Further, ball bearings or the like that reduce the rotational resistance of the insertion portion 25 may be provided on the periphery of the openings 26 and 27. The external appearance of the cylindrical member 12 can be appropriately changed as long as it has openings 26 and 27 and supports the insertion portion 25 in a rotatable manner. For example, the tubular member 12 may be generally box-shaped or cylindrical.

  Cylindrical fixed shafts 28 and 29 (FIG. 2) protrude from the cylindrical member 12 in the first horizontal direction 6 in the facing direction. The fixed shafts 28 and 29 are inserted into the openings 30 and 31 (FIG. 2) of the arms 13 and 14, respectively, and rotatably support the arms 13 and 14. The openings 44 and 45 described above are formed at the tips of the fixed shafts 28 and 29, respectively. The openings 44 and 45 communicate the internal space of the tubular member 12 with the internal spaces of the arms 13 and 14.

[Arms 13, 14]
The arms 13 and 14 shown in FIGS. 1 and 2 have a generally cylindrical appearance in which openings 30 and 31 are formed on one end side. The inner diameters of the openings 30 and 31 are slightly larger than the outer diameters of the fixed shafts 28 and 29 so as to rotatably support the fixed shafts 28 and 29. Further, ball bearings or the like for reducing the rotational resistance of the fixed shafts 28 and 29 may be provided at the peripheral edges of the openings 30 and 31. The fixed shaft 28 is inserted into the opening 30 of the arm 13, and the fixed shaft 29 is inserted into the opening 31 of the arm 14. The fixed shafts 28 and 29 are arranged so that the central axes coincide with each other.

  After being inserted into the openings 30 and 31, a retaining member (not shown) for retaining is attached to the tips of the fixed shafts 28 and 29. This locking member is locked in the first horizontal direction 6 inside the arms 13 and 14, and the fixed shafts 28 and 29 are prevented from coming out of the openings 30 and 31. Although the thing of arbitrary shapes is used for a locking member, it is a ring shape as an example. However, the fixing shafts 28 and 29 may be provided with a means for preventing the slippage different from this.

  Bevel gears 16 and 17 are fitted around the ends of the arms 13 and 14 on the cylindrical member 12 side. The bevel gears 16 and 17 have the same tapered shape as the bevel gear 15. The bevel gears 16 and 17 mesh with the bevel gear 15, respectively. Second wings 19a and 19b, which will be described later, are formed on the other ends of the arms 13 and 14, respectively.

[First wing 18]
The first wing 18 shown in FIGS. 1 and 2 is provided around the lower end portion of the main body 11, specifically, above the perforated portion 43 in the tip member 22. The first blade 18 is composed of two elongated steel plates that protrude in opposite directions perpendicular to the vertical direction 5. The steel plates are inclined and curved in the same direction as viewed from the outer peripheral side.

  When the first wing 18 is in contact with the ground and rotated in a predetermined direction (clockwise as viewed from above in the present embodiment) while the main body 11 is pressed downward, the first wing 18 moves over the ground surface. After excavation, the ground stirring device 10 is penetrated into the ground. In addition, after the first blade 18 is buried in the ground, the first blade 18 functions as a screw, and generates a downward propulsive force that penetrates the ground stirring device 10 into the ground. Further, after the solidified material is discharged from the discharge hole, the solidified material and the soil and sand constituting the ground are agitated and mixed by the rotation of the first blade 18.

  Although the 1st wing | blade 18 is attached to the front-end | tip member 22 by arbitrary methods, for example, after inserting in the slit (not shown) formed in the side surface of the front-end | tip member 22, you may be fixed by welding etc.

  However, the shape of the first blade 18 described above is merely an example. If the 1st wing | blade 18 excavates the ground and stirs and mixes the solidification material and the soil and sand which comprise the ground, you may be comprised in the shape different from the thing of this embodiment.

[Second wing 19a, 19b]
Second wings 19a and 19b shown in FIGS. 1, 2 and 3 are formed at the ends of arms 13 and 14 opposite to the openings 30 and 31, respectively. FIG. 3 shows only the second wing 19a, but the second wings 19a and 19b are configured in the same shape.

  The second wings 19a and 19b are constituted by two substantially T-shaped steel plates that protrude from the arms 13 and 14 in opposite directions perpendicular to the first horizontal direction 6, respectively. That is, the second blades 19a and 19b are configured by a total of four steel plates. In this steel plate, a portion corresponding to a vertical line of the alphabet “T” is referred to as a protruding portion 34, and a portion corresponding to a horizontal line is referred to as a developed portion 35. The tips of the protrusions 34 are connected to the arms 13 and 14, respectively. As shown in FIG. 3A, the projecting portions 34 facing each other via the arms 13 and 14 are twisted in directions opposite to each other. Therefore, as shown in FIG. 3C, the two expanded portions 35 intersect each other when viewed from the longitudinal direction of the protruding portion 34. This shape is for the second blades 19a and 19b to efficiently agitate and mix the ground.

  The outer peripheral surface of the development part 35 is formed in a curved surface shape. A plurality of barbs 36 are projected along the outer peripheral surface of the deployment part 35. The tip of the spine 36 is pointed and has a shape that makes it easy to pulverize the hard soil that constitutes the ground.

  The distance L2 (FIG. 1A) between the tips of the two second blades 19a and 19b is longer than the maximum diameter L1 of the first blade 18 (FIG. 1B). Further, the maximum diameter L3 (FIG. 1B) of the second blades 19a and 19b is longer than L1. That is, when viewed from the vertical direction 5, a part of the second wings 19 a and 19 b is outside the circle formed by the rotation trajectory of the first wing 18.

  In such a configuration, the second blades 19a and 19b can stir and mix up to regions outside the first horizontal direction 6 and the first horizontal direction 7 from the region where the first blade 18 can stir the ground. It is. The section agitated and mixed by the first blade 18 and the second blades 19a and 19b has a generally rectangular shape of L2 × L3 when viewed from the vertical direction 5. However, L2 and L3 may be the same length as L1 at the shortest.

[Auxiliary wings 37a, 37b]
Further, auxiliary wings 37a and 37b for assisting the stirring and mixing of the ground are provided on the side surfaces of the cylindrical member 21 and the tip member 22, respectively. The auxiliary wing 37 a of the cylindrical member 21 is provided on the upper side of the bevel gear 15, and the auxiliary wing 37 b of the tip member 22 is provided on the lower side of the locking plate 32. The auxiliary wings 37a and 37b are elongated plates that protrude from the side surfaces of the cylindrical member 21 and the tip member 22, respectively. The auxiliary wings 37a and 37b are 90 ° out of phase in the circumferential direction, and the cylindrical member 21 And four pieces are arranged for each tip member 22. The auxiliary blades 37a and 37b are inclined in the same direction as the first blade 18 as viewed from the outside. The length of the auxiliary blade 37 in the radial direction (longitudinal direction) is shorter than that of the first blade 18 and is long enough not to interfere with the second blades 19a and 19b.

[Penetration device 38]
The penetration device 38 shown in FIG. 4 is used to penetrate the ground stirring device 10 into the ground. Since the penetration device 38 is known, an example of its configuration will be briefly described. The penetration device 38 according to the present embodiment includes a support column 39, an auger 40 attached to the support column 39, a vehicle body 41, and the like.

  The auger 40 supports the upper end of the main body 11 and generates torque for rotation. In addition, the auger 40 can move in the vertical direction 5 along the support column 39 in a state where torque is applied to the main body 11. Driving force is transmitted from different motors (not shown) for rotation of the main body 11 and vertical movement of the auger 40. When the auger 40 moves downward with the main body 11 supported, the ground stirring device 10 is pressed against the ground. In this state, the ground stirring device 10 penetrates into the ground by rotating the main body 11.

  The support column 39 is supported by an arbitrary method, but is attached to and supported by the vehicle body 41 in the present embodiment. The vehicle body 41 is a heavy machine, and the auger 40 can be operated from the cockpit.

  However, as long as the penetration device 38 penetrates the ground agitating device 10 into the ground, a different structure may be used. For example, the penetrating device 38 is not necessarily integrated with the vehicle body 41.

[Formation of ground improved prisms]
Hereinafter, a method of forming the ground improved prismatic body in the ground using the ground stirring device 10 and the penetration device 38 described above will be described. As shown in FIG. 4A, the ground stirring device 10 is placed on the ground 42 of the target section. The perforated part 43 is pierced into the ground 42 and the ground stirring device 10 is self-supporting. In this state, the upper end portion of the main body 11 is supported by the auger 40.

  A force that moves downward acts on the auger 40, and at the same time, torque is applied to the main body 11. The direction of the torque is the direction in which the first blade 18 produces a downward driving force (clockwise as viewed from above in the present embodiment).

  In a state where the lower end portion of the ground stirring device 10 is buried in the ground 42, the arms 13 and 14 receive resistance from the ground 42. Thereby, the cylinder 12 does not rotate integrally with the main body 11, and the main body 11 rotates relative to the cylinder 12. The rotation of the main body 11 is transmitted to the arms 13 and 14 via the bevel gears 15, 16 and 17. As a result, the second blades 19a and 19b rotate integrally with the arms 13 and 14.

  In the process in which the ground agitating device 10 is inserted, the first blade 18 excavates the ground 42 in advance, and the second blades 19a and 19b and the auxiliary blades 37a and 37b further agitate the region excavated by the first blade 18. To do. At the same time, the second wings 19 a and 19 b excavate a region further outside the region excavated by the first wing 18. The process of penetrating the ground stirring device 10 into the ground 42 is an example of the penetrating process of the present invention.

  After the ground agitation device 10 has penetrated to the target depth (the state in FIG. 4B), the direction of the torque applied to the main body 11 is reversed. As a result, the rotation of the main body 11 is reversed, and the first blade 18 generates an upward driving force. At the same time, an upward force is applied to the auger 40, and the ground agitating device 10 is raised.

  The solidifying agent is poured into the flow path inside the ground agitator 10 while repeating the ascent and descent of the ground agitator 10. As the solidifying agent, a cement-based one is generally used. After passing through the flow path, the solidifying agent is discharged into the ground from each discharge hole. The solidifying agent may be supplied from the penetration device 38 to the ground agitation device 10 or may be supplied from different equipment to the ground agitation device 10 via a tube or the like. The first wing 18, the second wings 19a and 19b, and the auxiliary wings 37a and 37b stir and mix the soil and sand constituting the ground 42 and the solidifying agent. This step is an example of the solidifying agent mixing step of the present invention.

  After the agitation and mixing are sufficiently performed, the ground agitating device 10 is raised and removed from the ground 42. Thereafter, the solidifying agent remaining in the ground is solidified, so that a substantially rectangular parallelepiped ground improved prism is formed in the ground. This ground improvement prismatic body is substantially rectangular of L2 × L3 when viewed from the vertical direction 5. Moreover, the ground improvement prismatic body is formed from the ground surface to the deepest part where the 1st wing | blade 18 penetrated.

  If necessary, the ground-improved prismatic body can be formed in a wider section by executing the above-described series of steps a plurality of times while shifting the target section that penetrates the ground stirring device 10.

[Operational effects of this embodiment]
In the ground stirring device 10 according to the present embodiment, the ground improved prismatic body can be formed in a generally rectangular section of L2 × L3 in plan view. Thereby, a ground improvement prismatic body can be formed in a rectangular adjacent section without a gap.

  Details will be described below. In the conventional configuration not including the second wings 19a and 19b, the ground improvement body is formed in a substantially circular section by a single construction. Therefore, when the construction is performed a plurality of times by the “circular contact arrangement”, as shown in FIG. 5A, the non-stirring region E2 with insufficient stirring is formed in the gap between the stirring regions E1 where stirring is performed. It is formed.

  On the other hand, in the ground agitation device 10 according to the present embodiment, since the ground improvement prismatic body is formed in the L2 × L3 section by one construction, as shown in FIG. E1 can be arranged adjacent to each other without a gap. Thereby, the supporting force of the ground improvement prism body formed as a whole improves rather than the conventional ground improvement body. In FIG. 5B, an example of L2 = L3 is shown.

  Further, in the ground agitation device 10 according to the present embodiment, the rotation of the main body 11 is transmitted to the second blades 19a and 19b via the bevel gears 15, 16, and 17, so that the second blades 19a and 19b are rotated. The configuration is easily realized and the configuration of the penetrating device 38 is simplified. That is, as the penetration device 38, a known device that simply penetrates the ground stirring device 10 into the ground can be used.

  Moreover, since the main body 11 is comprised from the cylindrical member 21 and the front-end | tip member 22, the assembly of the ground stirring apparatus 10 is easy. In particular, it is possible to transfer the ground stirring device 10 in a disassembled state and immediately assemble it before construction.

  Further, the bevel gear 15 and the locking plate 32 prevent the cylindrical member 12 from moving in the vertical direction 5.

[Modification 1]
As shown in FIG. 6, a housing 48 that accommodates the bevel gears 15, 16, and 17 may be used instead of the tubular member 12. The point that the housing 48 is rotatably fitted to the main body 11 and the point that the housing 48 rotatably supports the arms 13 and 14 are the same as those of the cylindrical member 12 described above. In FIG. 6, the housing 48 is shown in a cubic shape, but the shape can be changed as appropriate.

[Modification 2]
Moreover, when the length of the ground stirring apparatus 10 is insufficient to reach the first wing 18 and the second wings 19 a and 19 b to the target depth, the pipe body 47 may be joined to the main body 11.

  In detail, after penetrating the ground agitating device 10 until the upper end of the main body 11 is located near the ground surface (state of FIG. 4B), the pipe body 47 is joined to the upper end of the main body 11. The tubular body 47 has a cylindrical shape similar to that of the cylindrical member 21. For joining the pipe bodies 47, a technique such as welding may be used, or a dedicated joint may be used. Subsequently, the auger 40 is connected to the upper end of the tubular body 47, and the ground agitating device 10 integrated with the tubular body 47 is penetrated into the deeper portion of the ground 42 (state shown in FIG. 4C).

[Modification 3]
The number and shape of the first wing 18 and the second wings 19a and 19b described above are merely examples, and can be appropriately changed by those skilled in the art. For example, a total of four first blades 18 and second blades 19a and 19b may be projected with a phase shift of 90 ° in the circumferential direction. Moreover, the 1st blade | wing 18 may be comprised, for example in the spiral shape.

[Modification 4]
In order to transmit the rotation of the main body 11 to the second wings 19a and 19b, a method different from the above-described embodiment may be used. For example, the arms 13 and 14 do not need to rotate integrally with the second wings 19a and 19b, and may support the second wings 19a and 19b rotatably. The rotational driving force for the second wings 19a and 19b may be transmitted to the second wings 19a and 19b via, for example, a rotation shaft provided inside the arms 13 and 14.

[Modification 5]
In the above-described embodiment, the flow path and the discharge hole formed in the ground stirring device 10 are used to flow the solidifying agent into the ground, but the solidifying agent may be supplied to the ground in a different manner. Good. For example, the flow path may be a tube or a slit provided outside the main body 11. Alternatively, the solidifying agent may be poured into the ground by a device independent of the ground stirring device 10.

10 ... Ground stirring device 11 ... Body 15, 16, 17 ... Bevel gear (drive transmission unit)
18 ... 1st wing | blade 19a, 19b ... 2nd wing | blade 12 ... cylinder material (connection member)
13, 14 ... Arm (connection member)
21 ... Cylindrical member (first member)
22 ... Tip member (second member)
38 ... Penetration device 42 ... Ground 47 ... Tube

Claims (6)

A cylindrical body that is supported and rotated at its upper end;
A first wing projecting in a direction intersecting the longitudinal direction of the main body and rotating integrally with the main body;
A connecting member that is rotatably fitted relative to the main body above the first wing, and in which arms protrude in opposite directions in a direction perpendicular to the longitudinal direction of the main body,
A second wing projecting in a direction intersecting the longitudinal direction of the arm and rotating about the longitudinal direction of the arm;
A drive transmission unit that transmits the rotation of the main body to the second wing,
A ground agitation device in which at least a part of a shape formed by projecting the second wing onto a virtual plane orthogonal to the longitudinal direction of the main body is outside a circle formed by a rotation locus of the first wing. The connecting member has a cylindrical member that is positioned with respect to the longitudinal direction of the main body and is externally fitted to the main body,
The ground agitating device according to claim 1, wherein the arm protrudes to the outside of the cylindrical member. The main body includes a cylindrical first member having an opening at a lower end, and a cylindrical second member provided with the first wing and inserted into the opening of the first member. The ground agitating device according to claim 1 or 2, wherein the cylindrical member is disposed at a connection portion between the first member and the second member.   The distance between the tips of the two second wings along the longitudinal direction of the arm and the maximum diameter of the second wing are each greater than or equal to the maximum diameter of the first wing. The ground agitation device described in 1.   The ground stirring device according to any one of claims 1 to 4, further comprising a flow path through which a solidifying agent injected into the ground is circulated and discharged along the longitudinal direction of the main body. A ground improved prismatic body that forms a ground improved prismatic body in the ground using the ground agitating device according to any one of claims 1 to 5 and a penetrating device capable of rotationally press-fitting the ground agitating device into the ground. A method,
While the main body is supported by the penetration device and rotated, a penetration step of press-fitting the ground stirring device into the ground,
A solidifying agent mixing step of rotating the first wing and the second wing while discharging the solidifying agent to the vicinity of the first wing or the second wing penetrating into the ground,
A method for producing a ground-improved prismatic body, wherein the penetration step and the solidifying agent mixing step are performed a plurality of times adjacent to a target section where a ground-improved prismatic body is to be formed.

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