JP2013129987A - Ground improvement machine and ground improvement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground improvement machine including a rotary type stirring device for increasing the support force of a ground improvement body from the ground positioned below the ground improvement body by forming a section of the ground improvement body (especially, the lower end section of the ground improvement body) having a large cross-sectional area in a horizontal direction including an area exceeding a rotational orbit of a stirring claw.SOLUTION: The ground improvement machine including a stirring device having a plurality of stirring claws 20 which rotate in a vertical direction includes a plurality of auxiliary stirring claws 21 each of which has a rotation radius which is equal to or less than a rotation radius A of the stirring claw 20 in a normal rotation (a) of the stirring claw 20, and each of which has a rotation radius B which is larger than the rotation radius A of the stirring claw 20 in a reverse rotation (b) of the stirring claw 20.

Description

  The present invention provides a ground improvement machine provided with a stirring device having a plurality of stirring claws rotating in the vertical direction (hereinafter also referred to as a rotary stirring device), and a ground and a solidified material slurry using the ground improvement machine. The present invention relates to a ground improvement method for forming a ground improvement body by mixing and stirring.

2. Description of the Related Art Conventionally, a ground improvement machine including a mobile base machine such as a backhoe and a rotary stirring device for mixing and stirring the ground (particularly, soft ground) and a solidified material slurry is known. Some of such ground improvement machines can obtain a ground penetration depth of 10 m or more to form a long prismatic ground improvement body (see Patent Document 1).
However, when using a ground improvement machine equipped with a rotary stirring device, the strength of the prismatic ground improvement body itself can be sufficiently increased by the solidifying slurry, but the horizontal cross-sectional area of the ground improvement body Since the size is determined by the rotation trajectory of a plurality of stirring claws for excavating the ground, for example, a portion of the ground improvement body having a large horizontal cross-sectional area including a region exceeding the rotation trajectory of the stirring claws is formed. Thus, it was not possible to increase the supporting force of the ground improvement body from the ground located below the ground improvement body (see FIGS. 4 and 5 of Patent Document 2).

JP 2009-221770 A JP 2006-144536 A

As described above, when performing ground improvement work with a ground improvement machine equipped with a rotary stirring device, the portion of the ground improvement body having a large cross-sectional area in the horizontal direction including the region exceeding the rotation trajectory of the stirring claws (particularly, It was not possible to increase the supporting force of the ground improvement body from the ground located below the ground improvement body by forming the lower end portion of the ground improvement body.
Therefore, the present invention is a ground improvement machine equipped with a rotary stirring device, and is a portion of a ground improvement body having a large horizontal cross-sectional area including a region exceeding the rotation trajectory of the stirring claws (particularly, ground improvement). A ground improvement machine capable of increasing the supporting force of the ground improvement body from the ground located below the ground improvement body, and solidifying with the ground using the ground improvement machine It aims at providing the ground improvement construction method which mixes and stirs material slurry and forms a ground improvement body.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor compared the rotary stirring device of the ground improvement machine equipped with the rotary stirring device with a stirring claw during the normal rotation of the stirring claw of the rotary stirring device. If a plurality of auxiliary stirring claws having a rotation radius smaller than the rotation radius and a rotation radius larger than the rotation radius of the stirring claws are added at the time of reverse rotation of the stirring claws, the lower end portion of the ground improvement body is formed. Sometimes, by rotating the stirring claw reversely, a portion of the ground improvement body having a larger radius (large width in the horizontal direction) than when the stirring claw is rotated forward can be formed. It has been found that the supporting force of the ground improvement body from the ground located below can be increased, and the present invention has been completed.

That is, the present invention provides the following [1] to [5].
[1] A ground improvement machine provided with a stirring device (rotary stirring device) having a plurality of stirring claws that rotate in the vertical direction, and having a rotation radius that is equal to or less than the rotation radius of the stirring claws during the normal rotation of the stirring claws. And a ground improvement machine comprising a plurality of auxiliary stirring claws having a rotation radius larger than the rotation radius of the stirring claws when the stirring claws are reversely rotated.
[2] A stirring claw mounting plate for supporting the plurality of stirring claws and the plurality of auxiliary stirring claws, and the stirring claw and the auxiliary stirring claws are alternately formed on the stirring claw mounting plate. The ground improvement machine according to [1] above.
[3] The auxiliary stirring claw has a curved shape. When the stirring claw is rotated forward, the auxiliary stirring claw is rotated so as to fall toward the concave portion of the curved shape by receiving earth pressure. It has a rotation radius equal to or less than the rotation radius of the stirring claw, and at the time of reverse rotation of the stirring claw, receives earth pressure, rotates to rise toward the convex portion of the curved shape, The ground improvement machine according to the above [1] or [2], which has a rotation radius larger than the rotation radius of the stirring claw.
[4] The rotation of the auxiliary stirring claw supported by two stirring claws located at both ends of the plurality of stirring claws and inserted through a through hole formed in the stirring claws other than the two stirring claws. The above-mentioned [1] to [3], which have a rotating shaft for movement, and wherein the plurality of auxiliary stirring claws are fixed to the rotating shaft and rotate with the rotation of the rotating shaft. The ground improvement machine described in any one.
[5] A ground improvement method using the ground improvement machine according to any one of [1] to [4], wherein the stirring device is lowered in the ground while the stirring claw is rotated forward. And when the stirring device reaches a desired depth in the ground, the stirring claws are rotated in reverse, and the solidifying material slurry is discharged to mix and stir the solidifying material slurry and the ground. The lower end portion forming step for forming the lower end portion of the ground improvement body having a radius larger than the rotation radius of the stirring claw, and (a) a method of performing only forward rotation, and (b) performing only reverse rotation of the stirring claw. And (c) an ascending step of ascending the agitator while rotating by any one of the method of performing at least one forward rotation and one reverse rotation, and the descending step In one or both of the above ascending steps The ground improvement construction method is characterized in that the solidification material slurry is discharged, and the solidification material slurry and the ground are mixed and stirred to form a portion of the ground improvement body other than the lower end portion of the ground improvement body.

According to the ground improvement machine of the present invention, when the stirring device descends in the ground, the stirring claw is rotated forward to form a prismatic ground stirring portion without generating a large resistance due to the auxiliary stirring claw. The stirring device can be efficiently lowered to the desired depth (the deepest point), and when the stirring device reaches the desired depth (the deepest point), the solidified material is rotated while the stirring claws are rotated in the reverse direction. By discharging the slurry, the ground improvement body having a shape with a larger projected area in the vertical direction than the prismatic ground stirring portion (specifically, a shape corresponding to the maximum turning radius of the auxiliary stirring claws) is obtained. The lower end portion can be formed, and as a result, the supporting force of the ground improvement body from the ground located below the ground improvement body can be increased.
Further, according to the ground improvement machine of the present invention, when the stirring device reaches a desired depth (the deepest point), the rotation radius of the auxiliary stirring claw is discharged by discharging the solidified material slurry while rotating the stirring claw backward. Compared to the case where the auxiliary stirring claw is not used, the ground improvement body can be formed up to the lower part of the ground by the length obtained by subtracting the rotation radius of the stirring claw from the above. In particular, at the deepest point of the ground to be improved (for example, soft ground), the ground improvement body to a deeper point than the case where there is no auxiliary stirring claw in the hard ground (supporting ground) below the ground. Can be made to bite in securely, and the supporting force of the ground improvement body by the supporting ground can be increased.
Since the ground improvement body formed using the ground improvement machine of the present invention has a large supporting force from the ground located below the ground improvement body, it has high stability even in soft ground.

It is a front view which shows an example of the ground improvement machine of this invention. The side view which shows the position of the auxiliary stirring claw at the time of forward rotation of the stirring apparatus of the ground improvement machine of this invention ((a) in a figure), and the side view which shows the position of the auxiliary stirring claw at the time of reverse rotation (in the figure) (B)). The figure for demonstrating rotation of the auxiliary stirring claw at the time of forward rotation of the stirring apparatus shown in FIG. 2 ((a) in a figure), and the figure for demonstrating rotation of the auxiliary stirring claw at the time of reverse rotation ((B) in the figure). It is the figure ((a) in a figure) which shows an example of the attachment position of the auxiliary stirring nail in the ground improvement machine of this invention, and the figure ((b) in a figure) which shows another example of this attachment position. The perspective view ((a) in the figure) near the lower end of the prismatic ground stirring portion formed in the descending step in the ground improvement method of the present invention, and a perspective view showing an example of the ground improvement body (( b)). It is a perspective view which shows the other example of the ground improvement body formed using the ground improvement machine of this invention.

Hereinafter, embodiments of the ground improvement machine of the present invention will be described with reference to the drawings.
In FIG. 1, a ground improvement machine 1 according to the present invention includes a base machine 4 in which a revolving body 3 is mounted on a traveling body 2, a swingable arm 5 attached to the base machine 4, A frame 6 hanging from the end portion and a stirring device 7 attached to the lower end of the frame 6 are provided.
A driver's seat is provided inside the revolving structure 3. The driver can control each part of the traveling body 2, the revolving body 3, the arm 5, and the stirring device 7 at the driver's seat.
The frame 6 is, for example, a hollow tubular member having a rectangular cross-sectional shape, and a hose (not shown) for supplying a solidifying material slurry is attached to the outside of the frame 6. The piping for driving the stirring device 7 is accommodated. The axis of the frame 6 (the center point of the rectangular cross-sectional shape) extends in the vertical direction. The frame 6 may be referred to as a casing.
The length of the frame 6 can be appropriately determined according to the length of excavation planned for the ground improvement work.

The stirring device 7 includes a support body 8 attached to the lower end of the frame 6, a rotating shaft 10 extending in the horizontal direction supported by the support body 8, and a stirring blade 11 supported by the rotating shaft 10 and rotatable in the vertical direction. Have
The support 8 includes, for example, a hollow tubular portion having a rectangular cross-sectional shape that extends below the frame 6. In the internal space of the hollow tubular portion of the support 8, piping for driving the stirring device 7 and the like are accommodated. The motor 9 is disposed above the stirring blade 11 as a component of the support 8. A motor 9 as a drive source transmits power to a rotating shaft (shaft body) 10 to rotate the stirring blade 11. In addition, an injection port (not shown) for injecting the solidifying material slurry is provided on the upper and lower portions of the support 8. In the ground improvement machine of the present invention, the ground (excavated soil) and the solidified slurry are mixed and stirred by the stirring device 7 to create a ground improvement body.

In FIG. 2, the stirring blade 11 includes a stirring blade portion 11 a having a plurality of stirring claws 20 and a plurality of auxiliary stirring claws 21, and a stirring blade portion 11 b having no auxiliary stirring claws 21 and having only the plurality of stirring claws 20. However, the four agitating blade portions as a whole are configured to form a cross shape by being alternately provided at intervals of 90 degrees in the rotation direction of the agitating blade 11.
FIG. 2 is for explaining the relationship between the rotation trajectory of the stirring claw 20 and the rotation trajectory of the auxiliary stirring claw 21. Details of the mounting positions of the stirring claw 20 and the auxiliary stirring claw 21 on the stirring blade 11 are as follows. This will be described later with reference to FIG.
The stirring claw 20 rotates with the rotating shaft 10 and always has the same rotation radius. The auxiliary stirring claw 21 rotates together with the rotary shaft 10 similarly to the stirring claw 20, but the rotation radius differs depending on the rotation direction as described later.

(A) in FIG. 2 shows the state of the stirring blade 11 when the stirring claw 20 is rotating in the direction of the arrow in the drawing (the direction opposite to the rotating direction of the hands of the watch). In this case, the auxiliary stirring claw 21 of the stirring blade portion 11a is in a collapsed state and is within the range of the rotation trajectory of the stirring claw 20 (indicated by symbol A in the figure). That is, in this case, the auxiliary stirring claw 21 has a rotation radius equal to or less than the rotation radius of the stirring claw 20. In addition, the rotation state of the stirring blade 11 (or the stirring claw 20) that causes the auxiliary stirring claw 21 to fall is referred to as “forward rotation” in the present specification.
(B) in FIG. 2 shows the state of the stirring blade 11 when the stirring claw 20 is rotating in the direction of the arrow in the drawing (the same direction as the rotating direction of the hands of the watch). In this case, the auxiliary stirring claw 21 is in a raised state and has a rotation trajectory (indicated by symbol B in the figure) that exceeds the rotation trajectory of the stirring claw 20 (indicated by symbol A in the figure). That is, in this case, the auxiliary stirring claw 21 has a rotation radius larger than the rotation radius of the stirring claw 20. In addition, the rotation state of the stirring blade 11 (or the stirring claw 20) in which the auxiliary stirring claw 21 is raised is referred to as “reverse rotation” in the present specification.

(A), (b) in FIG. 3 is a figure for demonstrating rotation of the auxiliary stirring nail | claw 21 corresponding to (a), (b) in FIG. 2, respectively.
In FIG. 3, the auxiliary stirring claw 21 has a curved shape, and has a convex portion 21 </ b> A and a concave portion 21 </ b> B as the contour of the curved shape.
The auxiliary stirring claw 21 is fixed to the rotating shaft 22 for rotating the auxiliary stirring claw, and can rotate with the rotation of the rotating shaft 22. As shown in FIG. 4, the rotating shaft 22 is rotatably supported by bearings provided on two stirring claws located at both ends of the plurality of stirring claws 20, and the stirring claws at the both ends are also supported. It is rotatably inserted in a through hole formed in the stirring claw other than the above.

As shown in FIGS. 3A and 3B, the auxiliary stirring claw 21 is fixed to the end of the arm 30 that is rotationally driven by the rotating shaft 10 (see FIGS. 2 and 4) of the stirring blade 11. Further, a range of rotation is determined by contacting the surface of the stirring claw mounting plate 31.
3 (a), the auxiliary stirring claw 21 receives earth pressure from below in the drawing and rotates so as to fall toward the concave portion 21B, so that the surface 21b and the surface 21c are the stirring claw mounting plate. The surface 21 a is in contact with the stirring claw mounting plate 31.
On the other hand, in (b) of FIG. 3, the auxiliary stirring claw 21 receives earth pressure from above in the drawing and rotates so as to rise up toward the convex portion 21A, and the surfaces 21a and 21b are stirred. The claw mounting plate 31 is lifted up and the surface 21 c is in contact with the stirring claw mounting plate 31. Thus, the auxiliary stirring claw 21 can be rotated between (a) and (b) in FIG.
Note that an elastic member such as a spring may be attached to the auxiliary stirring claw 21 so that the state (a) in FIG. 3 is always obtained when an external force such as earth pressure does not work.

In FIG. 4A, a pair of stirring blades 11 are disposed on both the left and right sides of the support 8.
Each of the pair of stirring blades 11 includes two stirring blade portions 11a having the auxiliary stirring claws 21 and two stirring blade portions 11b having no auxiliary stirring claws 21 as described above.
Among these, as shown in FIG. 4A, the stirring blade portion 11 a includes an arm portion 30 extending radially outward from the rotary shaft 10 and a horizontally extending plate fixed to the tip of the arm portion 30. A stirring claw mounting plate 31 which is a body, a plurality of stirring claws 20 fixed to the stirring claw mounting plate 31 and extending from the stirring claw mounting plate 31 toward the opposite side of the arm portion 30, A rotating shaft 22 pivotally supported by the stirring claws 20 at both ends, and a plurality of auxiliary stirring claws 21 fixed to the rotating shaft 22 and extending from the vicinity of the stirring claw mounting plate 31 toward the opposite side of the arm portion 30 (in the drawing, (Hatched). The auxiliary stirring claw 21 is not fixed to the stirring claw mounting plate 31, has an appropriate space between the auxiliary claw mounting plate 31, and rotates as the rotary shaft 22 rotates.

As shown in FIG. 4A, the stirring blade 11 includes a stirring blade portion 11a provided with four stirring claws 20 and three auxiliary stirring claws 21, and three stirring claws 20 and two auxiliary blades. It has what the stirring nail | claw 21 was provided. In any of these two types of stirring blade portions 11a, the stirring claws 20 and the auxiliary stirring claws 21 are alternately provided with appropriate intervals. By combining the two types of stirring blade portions 11a, the uniformity of ground stirring can be enhanced.
The two stirring blade portions 11b not having the auxiliary stirring claws 21 are arranged so as to intersect perpendicularly with respect to the two stirring blade portions 11a in FIG. These two stirring blade portions 11b can be configured as a combination of a stirring blade portion 11b having five stirring claws 20 and a stirring blade portion 11b having four stirring claws 20, for example. In this case, if the rotation trajectory of the stirring blade portion 11b having the five stirring claws and the rotation locus of the stirring blade portion 11b having the four stirring claws do not overlap, the uniformity of the ground stirring can be improved. Can be increased.

A stick-shaped attached earthing bit 32 is fixed to the arm 30 so as to extend in the horizontal direction. The stirring claw mounting plate 31 is a plate body extending in the horizontal direction as described above, and always extends in the horizontal direction even if the position of the stirring claw mounting plate 31 is changed by the rotation of the rotating shaft 10.
Instead of the form shown in FIG. 4A, the form shown in FIG. 4B may be adopted. In this case, the auxiliary stirring claw 21 is disposed in the vicinity of the stirring claw 20 (for example, a position where they are brought into contact with each other or a slight gap is interposed).
The form shown in FIG. 4A is advantageous in that the uniformity of ground agitation can be improved. On the other hand, since the auxiliary stirring claw 21 is provided in the vicinity of the stirring claw 20 in the form shown in FIG. 4B, there is an advantage that it is easy to excavate even when the hardness of the ground is relatively high.

Next, the ground improvement method of the present invention will be described.
An example of the ground improvement method of the present invention is a ground improvement method using the above-described ground improvement machine. (A) While the stirring claw 20 is rotated forward, the stirring device 7 is lowered in the ground. Then, the solidifying material slurry is discharged, and the solidifying material slurry and the ground are mixed and stirred to form a ground stirring portion (a part of the ground improvement body) 40 ((a) of FIG. 2 and ( a)) and when the stirring device 7 reaches a desired depth in the ground, the stirring claws 20 are rotated in reverse, and the solidified material slurry is discharged to mix and stir the slurry and the ground. A lower end portion forming step (see FIGS. 2B and 5B) for forming the lower end portion 41 of the ground improvement body having a radius larger than the rotation radius of 20, and the stirring claw 20 While rotating, raise the stirring device 7 to complete the ground improvement body. Increasing step of, is intended to include.
In this example, only the lower end portion of the ground improvement body has a larger projected area in the vertical direction than the other portions. In this case, there are advantages that the stirring device 7 can be efficiently lowered and raised in the ground, and the supporting force of the ground improvement body from the ground below the ground improvement body is increased.

In the present invention, when raising the stirring device 7, instead of the method of performing only forward rotation as described above, a method of performing only reverse rotation, or a method of performing forward rotation and reverse rotation at least once each, Can be adopted.
Among these, when the method of performing only reverse rotation is adopted, the ground improvement body 42 having a shape as shown in FIG. 6 can be obtained. In addition, the dotted line in FIG. 6 has shown the shape of (b) of FIG. 5 for the comparison. In this case, there is an advantage that the supporting force of the ground improvement body from the ground below the ground improvement body is increased. However, since the rotation radius of the auxiliary stirring claw is large, the resistance from the ground increases, and the speed of ascending of the stirring device 7 in the ground is slightly reduced.
Moreover, when the method of performing forward rotation and reverse rotation at least once each is used, a ground improvement body whose vertical cross-sectional shape is a dumpling shape can be obtained. In this case, there is an advantage that the supporting force of the ground improvement body from below and around the ground improvement body is increased. However, since the rotation radius of the auxiliary stirring claw increases during reverse rotation and the resistance from the ground increases, the speed of ascent of the stirring device 7 in the ground slightly decreases during reverse rotation.
In the present invention, the discharge of the solidifying material slurry may be performed only in the descending process as described above, or may be performed only in the ascending process, or in both the descending process and the ascending process.

DESCRIPTION OF SYMBOLS 1 Ground improvement machine 2 Running body 3 Revolving body 4 Base machine 5 Arm 6 Frame 7 Stirrer 8 Support body 9 Motor 10 Rotating shaft (shaft body) of stirring blade
DESCRIPTION OF SYMBOLS 11 Stirring blade 11a Stirring blade part 11b which has an auxiliary stirring claw Stirring blade part 20 which does not have an auxiliary stirring claw 20 Stirring claw 21 Auxiliary stirring claw 21a-21c Surface 22 of auxiliary stirring claw )
30 Arm 31 Agitating claw mounting plate 32 Adhesive earthmoving bit 40 Ground agitating part (part of ground improvement body)
41 Lower end portion 42 of ground improvement body Ground improvement body

Claims (5)

  A ground improvement machine provided with a stirring device having a plurality of stirring claws that rotate in a vertical direction, having a rotation radius that is equal to or less than the rotation radius of the stirring claws when the stirring claws are rotating forward, and the reverse of the stirring claws A ground improvement machine comprising a plurality of auxiliary stirring claws having a rotation radius larger than the rotation radius of the stirring claws during rotation.   A stirring claw mounting plate for supporting the plurality of stirring claws and the plurality of auxiliary stirring claws, and the stirring claw and the auxiliary stirring claws are alternately formed on the stirring claw mounting plate. The ground improvement machine according to 1.   The auxiliary stirring claw has a curved shape, and when the stirring claw is rotated forward, it receives earth pressure and rotates so as to fall toward the concave portion of the curved shape. When the agitating claw is rotated in reverse, the agitating claw is rotated so as to rise up toward the curved convex portion when receiving the earth pressure. The ground improvement machine according to claim 1 or 2, which has a turning radius larger than the turning radius.   Rotation for rotation of the auxiliary stirring claw pivotally supported by two stirring claws located at both ends of the plurality of stirring claws and inserted through a through hole formed in the stirring claws other than the two stirring claws The shaft according to any one of claims 1 to 3, wherein the plurality of auxiliary stirring claws are fixed to the rotating shaft and are rotated along with the rotation of the rotating shaft. Ground improvement machine. A ground improvement method using the ground improvement machine according to any one of claims 1 to 4,
A lowering step of lowering the stirring device in the ground while rotating the stirring claw forward,
When the stirring device reaches a desired depth in the ground, the stirring claws are rotated in reverse, and the solidification material slurry is discharged to mix and stir the solidification material slurry and the ground. A lower end portion forming step for forming a lower end portion of the ground improvement body having a larger radius,
The stirring claw is rotated by any one of (a) a method for performing only forward rotation, (b) a method for performing only reverse rotation, and (c) a method for performing forward rotation and reverse rotation at least once each. Ascending step to raise the stirring device while
And in any one or both of the descending step and the ascending step, the solidifying material slurry is discharged, and the solidifying material slurry and the ground are mixed and stirred to improve the ground other than the lower end portion of the ground improving body. A ground improvement method characterized by forming a body part.

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