JP2019196591A - Excavating and stirring head - Google Patents

Abstract

To provide an excavating and stirring head which make it possible to continuously construct a steel pipe soil cement pile by reducing resistance to excavation by a hard ground.SOLUTION: An excavating and stirring head includes: excavating blades 3 at a tip portion of a rotation axis 2; and stirring blades 4 and corotation preventing blades 5 above the excavating blades 3. The corotation preventing blade 5 comprises a corotation preventing blade base portion 8 and a corotation preventing blade tip portion 9. The corotation preventing blade tip portion 9 is connected to the corotation preventing blade base portion 8 by a fulcrum pin 13 and a shear pin 14 in a direction perpendicular to a longer direction of the corotation preventing blade 5. When the shear pin 14 is broken by receiving shearing force equal to or larger than prescribed force by resistance to excavation of a ground, the corotation preventing blade tip portion 9 rotates about the fulcrum pin 13. The corotation preventing blade base portion 8 and the corotation preventing blade tip portion 9 include contact portions 9d, 12a which come in contact with each other when the corotation preventing blade tip portion 9 rotates about the fulcrum pin 13 by an angle equal to or larger than a prescribed angle. Frictional resistance between the contact portions 9d, 12a restricts rotation of the corotation preventing blade tip portion 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an excavation stirring head for steel pipe soil cement pile construction used in the construction of a steel pipe soil cement pile composed of a soil cement column and a steel pipe, and in particular, reduces the resistance to excavation by the hard ground even after reaching the hard ground. In addition to enabling continuous construction of steel pipe soil cement piles, the construction can be quickly raised to the surface after completion of construction.

  The steel pipe soil cement pile is constructed by constructing a soil cement column made of excavated soil and a solidified material (for example, cement milk) in the ground, and substituting a steel pipe such as a steel pipe with an external projection in the ground. In addition, the soil cement column is, for example, mixed agitation having a drilling blade (2), a stirring blade (3), and a co-rotation preventing blade (4) on a drilling shaft (1) as disclosed in Patent Document 1. While excavating the ground with the excavating blade (2), the solidified material is discharged from the tip of the excavating shaft (1), and the excavated soil and the solidified material are mixed with the stirring blade (2) and the anti-rotation blade (4). It is built by mixing and stirring.

  In particular, the co-rotation prevention blade (4) is installed between the excavation blade (2) and the stirring blade (3) in a rotation-free state, and is longer than the excavation blade (2) and the stirring blade (3), and has a tip. If the excavation blade (2) and the stirring blade (3) rotate along with the excavation shaft (1) in the ground without rotating, the excavation blade (2) and the agitation blade (3) do not rotate and cut the surrounding ground. It advances with the excavating blade (2) and the stirring blade (3).

  For this reason, when reaching the hard ground, there is a possibility that a large excavation resistance acts on the co-rotation preventing wing (4) and the construction efficiency is greatly reduced, or even the construction of the soil cement column becomes impossible.

  As an apparatus for solving these problems, for example, Patent Document 2 discloses a drilling blade (2) and a stirring blade that are attached to a tip of a drilling rod (1) and a position above the drilling rod (1) and rotate together with the drilling rod (1). (4) An invention of an excavation rod for ground improvement having a co-rotation prevention blade (3) installed in a rotation-free state between the excavation blade (2) and the stirring blade (4) is disclosed.

  In particular, the co-rotation prevention wing (3) is pivotally supported by the bracket (7) fixed to the boss (5) circumscribing the excavation rod (1) in a rotation-free state so as to be rotatable upward from the horizontal state, And when it is horizontal, it extends to the front of the excavating blade (2) and the stirring blade (4).

  In addition, when the co-rotation prevention wing (3) rotates upward and becomes inclined, the urging means (9) and the co-rotation prevention wing return the co-rotation prevention wing (3) to the original horizontal state. A biasing means (9) is provided with a shear pin (10) that maintains the horizontal state of (3) and breaks by a rotational force of a certain amount or more and allows the co-rotation prevention wing (3) to rotate upward. A spring with a small number of springs is used.

Japanese Patent Publication No.58-29374 JP 2012-188856 A

  However, the excavation rod for ground improvement disclosed in Patent Document 2 has the biasing means (9) in the soil cement during construction, and therefore the biasing means (9) is caused by the change or variation in the consistency of the soil cement. Performance (spring constant) may change, and the co-rotation prevention blade (3) may not operate properly.

  Further, after the construction, there is a possibility that the urging means (9) may become inoperable due to hardening with the soil cement adhered. However, it is difficult to remove the hardened soil cement during reuse. Therefore, after the construction, the attached soil cement must be carefully removed, which requires a lot of time and effort.

  Furthermore, as shown in FIGS. 9 and 10, the configuration in which the biasing means (9) is built in the hollow cylindrical shaft (15) may cause problems such as a complicated structure and increased cost.

  The present invention has been made in order to solve the above-described problems. In addition to preventing the co-rotation phenomenon of excavated soil, the soil cement can reduce the resistance of the co-rotation preventing wing from reaching the ground even after hitting the hard ground. An object of the present invention is to provide an excavation agitation head capable of efficiently continuing the construction of steel pipe piles.

  The present invention is connected to a drilling rod, and includes a drilling blade, a stirring blade, and a co-rotation preventing blade, and while stirring and mixing with the ground while discharging a solidified material such as cement milk from the tip, a soil cement column is formed. It is an invention of an excavation and stirring head that is constructed and used to embed a steel pipe in the soil cement column, wherein the co-rotation prevention wing includes a co-rotation prevention wing base and a co-rotation prevention wing tip. The anti-rotation blade tip is connected to the co-rotation blade base via a fulcrum pin in a direction orthogonal to the longitudinal direction of the co-rotation blade and a shear pin in a direction orthogonal to the longitudinal direction of the co-rotation blade. When a shearing force greater than a predetermined value acts on the shear pin due to the resistance force received by the tip of the co-rotation preventing wing from the ground, the shear pin breaks, and the tip of the co-rotation preventing wing rotates around the fulcrum pin. And it is characterized in that is possible.

  In particular, when the shear pin receives a shearing force of a predetermined level or more, it breaks, and the tip of the co-rotation preventing wing rotates so as to rotate upward (counterclockwise direction (arrow direction) in FIG. 1) from the horizontal state around the fulcrum pin. By being configured, even if it hits the hard ground during construction of steel pipe soil cement piles, the resistance force by the hard ground is reduced by rotating the tip of the co-rotation prevention wing around the fulcrum pin and turning upward Therefore, the construction of the steel pipe soil cement pile can be carried out continuously without interruption.

  Note that the shearing force of a predetermined value or more is a resistance to excavation due to the hardness of the ground exceeding the shearing strength of the shear pin, and therefore has an optimum shearing strength according to the pushing capacity of the construction machine (excavating machine). By selecting and using the shear pin, the construction of the steel pipe soil cement pile can be performed extremely economically and efficiently.

  In addition, an abutting portion that abuts each other when the anti-rotation blade tip rotates upward by a predetermined angle or more about the fulcrum pin as an axis is formed in the anti-rotation blade base and the anti-rotation blade tip. In addition, by configuring such that the rotation of the tip of the co-rotation preventing wing is restrained by the frictional resistance at the contact portion, the tip of the co-rotation preventing wing can be reliably and firmly fixed in the upward state. .

  Thereby, especially when the excavation stirring head is pulled up after the completion of the excavation process of the steel pipe soil cement pile, it is not difficult to pull up the excavation stirring head because the tip of the co-rotation prevention blade returns to the horizontal state. In addition, the joint rotation prevention wing | tip tip part which turned upward can be returned to a horizontal state by pulling a wire etc. and pulling it strongly and pulling a contact part apart.

  In addition, the abutting portions that abut against each other gradually taper on the opposing surfaces of the anti-rotation blade base and the anti-rotation blade tip to the opposite circumferential directions of the fulcrum pin around the fulcrum pin. In this case, the contact portions strongly contact each other, so that both the upper end (counterclockwise direction (arrow direction) in FIG. 1) and the lower direction (clockwise direction) in FIG. The rotation can be firmly restrained.

  Further, the tip of the co-rotation preventing wing is connected to the base of the co-rotation preventing wing through a shear pin in a direction perpendicular to the longitudinal direction of the co-rotation preventing wing, and the tip of the co-rotation preventing wing receives from the ground. The shear pin may be configured to break away from the common rotation prevention blade base by breaking the shear pin when a shearing force of a predetermined level or more is applied to the shear pin by a resistance force.

  According to the present invention, in particular, the tip of the co-rotation preventing wing has a fulcrum pin in a direction perpendicular to the longitudinal direction of the co-rotation preventing wing and a shear pin in the direction perpendicular to the longitudinal direction of the co-rotation preventing wing with respect to the base of the co-rotation preventing wing. And when the shearing force of a predetermined level or more acts on the shear pin by the resistance force received from the ground by the anti-rotation blade tip, the shear pin is broken, so that the anti-rotation blade tip is the fulcrum pin. Even if it hits the hard ground during construction of the steel pipe soil cement pile, the tip of the co-rotation wing rotates upwards around the fulcrum pin as a hard part. Since the excavation resistance due to the ground is reduced, the construction of the steel pipe soil cement pile can be continued without interruption.

  In addition, the tip of the co-rotation prevention wing rotates due to the hard ground excavation resistance and turns upward, and then rotates when the contact portions of both the co-rotation prevention wing base and the co-rotation prevention wing tip make strong contact with each other. It can be firmly fixed in the upward upward state. Thus, after the excavation process of the steel pipe soil cement pile, when the excavation agitation head is pulled up, the tip of the co-rotation prevention blade does not return to the horizontal state, and the excavation agitation head can be smoothly pulled up to the ground surface.

FIG. 1A is a front view of an excavation and agitation head according to the present invention, and FIG. 1B is a cross-sectional view taken along line II in FIG. 1A. 2 is an enlarged view of the main part of the excavation and agitation head shown in FIG. 1, FIG. 2 (a) is an enlarged view of the part B in FIG. 1 (b), and FIG. 2 (b) is in FIG. 2 (a). FIG. FIGS. 3 (a), (b), (c), and (d) are explanatory views showing the operation of the tip of the co-rotation preventing wing of the co-rotation preventing wing. It is a front view of an excavation agitation head, illustrating another embodiment of the excavation agitation head of the present invention. 5 (a) and 5 (b) are explanatory views showing the operation of the joint rotation preventing blade tip of the joint rotation preventing blade in the embodiment of FIG. 6 (a), 6 (b), and 6 (c) are explanatory views showing the operation of the tip of the co-rotation preventing wing of the co-rotation preventing wing in the embodiment of FIG. FIGS. 7A and 7B illustrate a modified example of the excavating blade attached to the tip of the rotating shaft, FIG. 7A is a front view, and FIG. 7B is a bottom view.

  1-3 illustrate one embodiment of the present invention. In the figure, the excavation and agitation head 1 includes an excavation blade 3 at the tip of a rotary shaft 2 and a plurality of agitation blades 4 and a common rotation prevention blade 5 above the excavation blade 3.

  The rotary shaft 2 is provided with a discharge port (not shown) of a solidified material (for example, cement milk) injected from the ground through the rotary shaft 2 at the tip, and is freely attachable to and detachable from the excavation rod 6 that is rotated by power at the upper end. The connection part 7 connected to is provided.

  The stirring blades 4 are installed at equal intervals in the axial direction of the rotary shaft 2 and horizontally in the direction perpendicular to the rotary shaft 2, symmetrically installed in both directions of the rotary shaft 2 in the direction perpendicular to the axis of the rotary shaft 2, and the rotary shaft The rotary shaft 2, the excavating blade 3 and the stirring blade 4 are connected to the excavating rod 6 and are configured to rotate together with the excavating rod 6 at the same time. .

  The co-rotation prevention blade 5 is horizontally installed between the pair of upper and lower stirring blades 4 and 4 in the direction perpendicular to the axis of the rotary shaft 2 and symmetrically on both sides of the rotary shaft 2. The co-rotation preventing wing 5 includes a co-rotation prevention wing base 8 and a co-rotation prevention wing tip 9 positioned on the tip side thereof, and is longer than the excavation wing 3 and the stirring wing 4.

  The co-rotation preventing wing base 8 is composed of a rotating sleeve 10 circumscribing the rotating shaft 2 in a rotation-free state, and a bracket 11 installed horizontally on the side of the rotating sleeve 10 in the direction perpendicular to the axis of the rotating shaft 2. In addition, a loose fitting groove 12 is formed at the tip of the bracket 11. The loose fitting groove 12 is open in the distal direction of the co-rotation preventing blade base 8 and is formed continuously in the vertical direction.

  The co-rotation prevention blade tip 9 is formed in a thin plate shape in the axial direction of the rotary shaft 2 from the rotary support portion 9a and the cutter portion 9b located on the tip side of the rotary support portion 9a. A blade shape 9c that is formed in a plate shape that is long in the perpendicular direction and that has an arc shape from the upper end side to the lower end side is formed at the tip of the cutter portion 9b.

  The rotation support portion 9a is loosely fitted in the loose fitting groove 12 of the bracket 11 and is freely rotatable in the vertical direction together with the cutter portion 9b by a fulcrum pin 13 in a direction orthogonal to the longitudinal direction of the co-rotation preventing wing 5 on the bracket 11. It is pivotally supported. Further, the rotation support portion 9a is fixed in a state where the cutter portion 9b extends horizontally in the tip direction of the co-rotation preventing blade base 8 by a shear pin 14 in a direction orthogonal to the longitudinal direction of the co-rotation prevention blade 5. And it is being fixed to the state extended ahead from the front-end | tip of the excavation blade 3 and the stirring blade 4. FIG.

  As the shear pin 14, a support pin made of a material that has a shear strength smaller than that of the fulcrum pin 13 and that breaks when a predetermined or greater shear force acts is used. The shearing force exceeding the predetermined value is the resistance to excavation due to the hardness of the ground exceeding the shearing strength of the shear pin 14. Therefore, the shearing pin having the optimum shearing strength according to the pushing capacity of the construction machine (excavator). By selecting and using 14, steel pipe soil cement piles can be constructed very economically and efficiently.

  Further, on the inner side surface of the loose fitting groove 12 and the side surface of the rotation support portion 9a, the co-rotation preventing blade tip portion 9 is predetermined in the vertical direction (counterclockwise direction (arrow direction) in FIG. 1) with the fulcrum pin 13 as an axis. Contact portions 12a and 9d that contact each other when rotated more than an angle are formed, and the rotation of the co-rotation preventing blade tip portion 9 is upward (the arrow in FIG. 1) due to the frictional resistance between the contact portions 12a and 9c. The rotation in both the upward and downward directions is restricted at a predetermined angle.

  The contact portions 9d and 12a are each formed in a taper shape by gradually rising in the opposite circumferential directions of the fulcrum pin 13 around the fulcrum pin 13. For example, the contact portion 9d is formed in a taper shape that gradually rises upward (in the direction of the arrow in FIG. 1) around the fulcrum pin 13, and the contact portion 12a gradually decreases downward. It is formed in the taper shape which protrudes. The abutting portions 9d and 12a may be formed at symmetrical positions on both sides of the common rotation preventing blade tip portion 9.

  In such a configuration, even if the excavating blade 3 and the stirring blade 4 are rotated and dug in the ground together with the rotary shaft 2, the common rotation preventing blade 5 has the cutter portion 9b of the common rotation preventing blade tip 9 in the surrounding ground. It does not rotate by biting in, but digs in the ground together with the excavation blade 3 and the stirring blade 4 in the excavation hole. As a result, the solidified material discharged from the solidified material discharge port at the tip of the rotary shaft 2 and the excavated soil are stirred and mixed by the stirring blade 4 and the co-rotation preventing blade 5 to build a soil cement column.

  Further, when the cutter pin 9b of the anti-rotation blade tip 9 hits the hard ground and the shear pin 14 breaks due to a shearing force of a predetermined level or more acting on the shear pin 14, the common rotation prevention blade tip 9 pushes the support pin 13 into place. When the shaft rotates upward and rotates upward by a predetermined angle or more, the contact portion 9d of the rotation support portion 9a and the contact portion 12a of the bracket 11 come into strong contact with each other. The rotation of the tip 9 is constrained. Thereby, since the penetration resistance to the surrounding ground of the co-rotation prevention blade 5 is reduced or eliminated, the soil cement pillar is formed by further excavating the inside of the hard ground. Further, in the construction method in which the steel pipe is sunk in the soil cement simultaneously with the construction of the soil cement pillar, the excavation stirring head 1 can be smoothly pulled up to the ground after the steel pipe has been laid down.

  It should be noted that the length L of the co-rotation prevention blade 5 after the co-rotation prevention blade tip 9 rotates upward about the support pin 13 is the same as the length of the stirring blade 4 or the inner wall surface of the excavation hole (See FIG. 1).

  In such a configuration, when the construction of the steel pipe soil cement pile was experimentally carried out using the excavating and stirring head 1, in the hard ground having a certain hardness or more, the joint rotation preventing blade tip 9 is centered on the support pin 13. By rotating upward and folding, the penetration resistance of the co-rotation preventing wing 5 is reduced or eliminated, and a steel pipe soil cement pile can be formed without any problem even on hard ground.

  4 to 6 illustrate other embodiments of the present invention, in which the rotation support portion 9a of the anti-corotation blade tip portion 9 is loosely fitted in the loose fitting groove 12 of the bracket 11, and is attached to the bracket 11. FIG. They are connected via shear pins 14 in a direction orthogonal to the longitudinal direction of the co-rotation preventing blade 5. Further, since the rear end portion of the rotation support portion 9a is in contact with the bottom surface of the loose fitting groove 12, an upward direction and a downward direction (clockwise direction and counterclockwise direction) about the shear pin 14 of the co-rotation preventing blade tip portion 9 are used. Rotation in the clockwise direction (arrow direction in FIG. 4) is prevented.

  Further, in the bottom face portion of the loose fitting groove 12, the bearing receiving rotation pin 15 is in a direction orthogonal to the longitudinal direction of the co-rotation preventing blade 5 at a position facing the corner portion 9 e at the upper end of the rear end portion of the rotation support portion 9 a. It is attached. A corner portion 9e at the upper end of the rear end portion of the rotation support portion 9a is detachably inserted into the fitting groove 15a formed on the side portion of the bearing pressure receiving rotation pin 15.

  The bearing support rotating pin 15 is made of a steel material higher in strength than the rotation support portion 9a, and is filled with a lubricant (grease) so as to rotate smoothly.

  In such a configuration, the co-rotation preventing wing tip 9 receives the upward digging resistance force from the ground during excavation, and the shear pin 14 is broken when the shear pin 14 is applied with a shearing force of a predetermined level or more. The distal end portion 9 is configured to be disengaged from the co-rotation preventing blade base portion 8. That is, when the co-rotation preventing blade tip 9 receives an upward digging resistance force from the ground during excavation, and the shear pin 14 is subjected to a shearing force of a predetermined level or more, the shear pin 14 is deformed to fractured. The tip portion 9 is detached from the co-rotation preventing blade base 8 while rotating upward along with the bearing receiving rotation pin 15 around the corner portion 9e at the upper end of the rear end portion of the rotation support portion 9a (FIG. 6 (a), (See (b) and (c)).

  As described above, the support bearing rotating pin 15 made of a high-strength steel material is attached, so that damage to the joint rotation preventing blade base 8 of the joint rotation preventing blade 5 that is repeatedly used can be reduced.

  The length L of the co-rotation prevention blade 5 after the co-rotation prevention blade tip 9 is separated from the co-rotation prevention blade base 8 is approximately the same as the length of the stirring blade 4 or is almost on the inner wall surface of the excavation hole. It is configured to reach a length (see Figure 4).

  7 (a) and 7 (b) show a modification of the excavating blade 3 attached to the tip of the rotating shaft 2, and the excavating blade 3 is formed in a spiral shape in the axial direction of the rotating shaft 2. By using the excavated blades, the advancing force and the stirring and mixing force can be increased.

  In such a configuration, when the construction of the steel pipe soil cement pile was experimentally performed, the shear pin 14 was broken on the hard ground having a certain hardness or more, and the common rotation prevention blade tip 9 was the common rotation prevention blade base 8. By separating from the above, the penetration resistance of the co-rotation preventing wing 5 was reduced or eliminated, and a steel pipe soil cement pile could be formed without any problem even on hard ground.

  The present invention can continuously perform the construction of the steel pipe soil cement pile without interruption even after reaching the hard ground.

DESCRIPTION OF SYMBOLS 1 Excavation stirring head 2 Rotating shaft 3 Excavation blade 4 Stirring blade 5 Co-rotation prevention blade 6 Drilling rod 7 Connection part 8 Co-rotation prevention blade base 9 Co-rotation prevention blade tip
9a Rotation support
9b Cutter section
9c Blade type
9d contact part
9e Corner
10 Rotating sleeve
11 Bracket
12 Free fitting groove
12a Contact part
13 fulcrum pin
14 Sharpin
15 Bearing support rotating pin

Claims (3)

  Connected to the drilling rod, equipped with a drilling blade, a stirring blade, and a co-rotation prevention blade, discharged cement milk from the tip, mixed with the ground and built a soil cement column, and a steel pipe in the soil cement column In the excavation and agitation head used for burying, the co-rotation preventing wing includes a co-rotation prevention wing base and a co-rotation prevention wing tip, and the co-rotation prevention wing tip is connected to the co-rotation prevention wing base. On the other hand, it is connected via a fulcrum pin in a direction orthogonal to the longitudinal direction of the co-rotation preventing wing and a shear pin in a direction orthogonal to the longitudinal direction of the co-rotation preventing wing, and the resistance force received by the tip of the co-rotation preventing wing from the ground The shear pin breaks when a shearing force of a predetermined level or more is applied to the shear pin, so that the tip of the co-rotation preventing blade is rotatable about the fulcrum pin. Drilling stirring head that.   2. The excavation and agitation head according to claim 1, wherein the co-rotation preventing blade base and the co-rotation preventing blade tip are mutually connected when the tip of the co-rotation preventing blade rotates more than a predetermined angle about the fulcrum pin. An excavation and agitation head, wherein an abutting portion that abuts is formed, and the rotation of the tip of the co-rotation preventing blade is restricted by frictional resistance in the abutting portion.   Connected to the excavation rod, and equipped with excavation blades, agitation blades, and co-rotation prevention blades, discharge cement milk from the tip and mix and agitate with the ground to build a soil cement column, and in the soil cement column In the excavation and agitation head used to embed a steel pipe, the co-rotation prevention wing includes a co-rotation prevention wing base and a co-rotation prevention wing tip, and the co-rotation prevention wing tip is the co-rotation prevention wing base. On the other hand, it is connected via a shear pin in a direction orthogonal to the longitudinal direction of the co-rotation prevention wing, and when a shear force of a predetermined level or more acts on the shear pin by a resistance force received by the tip of the co-rotation prevention wing from the ground, An excavation and agitation head, wherein the shear pin is broken so that the tip of the joint prevention blade is detached from the joint prevention blade base.

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