Soil improving and agitating apparatus

Abstract

To provide a soil improvement stirring device capable of simplifying a system, having a constitution hardly causing damage, and capable of preventing a co-rotation phenomenon.SOLUTION: The soil improving and agitating apparatus 100 includes a tubular inner pipe 10 extending in a vertical direction, a tubular outer pipe 20 surrounding an outer periphery of the inner pipe 10 coaxially with the inner pipe 10 and rotatable relative to the inner pipe 10 fixed in a non-rotatable manner, an excavating and agitating member 30 provided at a lower end of the outer pipe 20 and rotating with rotation of the outer pipe 20, and an anti-corotation blade 40 projecting from the inner pipe 10 so as to be positioned between the excavating member 31 and the agitating blade 36 in the vertical direction and having a gap with the rotating excavating and agitating member 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ground improvement mixing device. [Background technology]

[0002] One ground improvement method is the mechanical mixing method, in which soil excavated with an excavator is rotated in the ground using a mixing blade to mix and stir the soil with a slurry-like solidification material, creating a solidified body (column) underground, thereby increasing the bearing capacity of soft ground. In this method, a phenomenon called co-rotation can occur, in which the excavated soil mass rotates together with the mixing blade. When this phenomenon occurs, the solidification material and soil are poorly mixed, resulting in the creation of an inhomogeneous solidified body, which may not achieve the desired quality.

[0003] Therefore, as a first technique for preventing co-rotation, a double inner / outer tube is constructed, consisting of an outer tube to which the drilling member and agitator blades are fixed and an inner tube to which another agitator blade is fixed, and the outer tube and inner tube are rotated in opposite directions relative to each other, and drilling is carried out while rotating the agitator blades in opposite directions relative to each other, thereby preventing the co-rotation phenomenon (see, for example, Patent Document 1).

[0004] As a second technique for preventing co-rotation, a co-rotation prevention blade with a radius larger than that of the agitator blade is attached to a rotating shaft to which the drilling member and agitator blade are fixed so that it can rotate freely relative to the rotating shaft, and the horizontal end of the co-rotation prevention blade is fixed by being embedded into the inner wall of the drilled hole while drilling is carried out, thereby preventing the co-rotation phenomenon (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3739620 [Patent Document 2] Japanese Patent Publication No. 2022-015199 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the first co-rotating technique described above requires a configuration for rotating the inner tube and the outer shaft relatively in opposite directions, which poses a problem of making the system complicated.

[0007] In the second anti-rotation technology, the horizontal end of the anti-rotation blade must be engaged with the ground around the borehole as the excavation progresses, and the blade must be inserted vertically downward. This makes penetration difficult, particularly in hard ground, and can lead to damage to the anti-rotation blade.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a ground improvement mixing device that allows for a simplified system, has a configuration that is less likely to break, and can prevent the phenomenon of co-rotation. [Means for solving the problem]

[0009] The ground improvement mixing device of the present invention is characterized by comprising: a tubular inner pipe extending in the vertical direction; a tubular outer pipe coaxially surrounding the outer periphery of the inner pipe and rotatable relative to the inner pipe which is fixed so as not to rotate; an excavation member provided at the lower end, an upper extension member extending upward from the radially outer part of the excavation member, and an agitation blade protruding from the inner surface of the upper extension member toward the inner pipe; an excavation / mixing member provided at the lower end of the outer pipe and rotating as the outer pipe rotates; and an anti-rotation blade protruding from the inner pipe so as to be positioned vertically between the excavation member and the agitation blade, and having a gap between it and the rotating excavation / mixing member.

[0010] According to the ground improvement mixing device of the present invention, the phenomenon of co-rotation, in which the soil excavated by the excavation member rotates together with the mixing blade, can be prevented by the anti-rotation blade that is fixed so that it cannot rotate. This eliminates the need for a mechanism to rotate the inner pipe, which simplifies the system compared to the first anti-rotation technology described above. Furthermore, compared to the second anti-rotation technology described above, it is not necessary to embed the horizontal end of the anti-rotation blade into the inner wall of the excavated hole in order to fix it, which reduces the risk of damage to the anti-rotation blade.

[0011] In the ground improvement mixing device of the present invention, the inner pipe has a supply port at its upper end through which a liquid or slurry material is supplied and a discharge port at its lower end through which the liquid or slurry material is discharged, and it is preferable that the tip of the inner pipe is located inside the through hole formed in the excavation member.

[0012] In this case, it is possible to supply a liquid such as water or a slurry such as a solidification material to the part excavated by the excavation member through the fixed inner pipe. Also, unlike the first and second co-rotation prevention techniques described above, there is no need to provide a swivel mechanism or other configuration required to supply water or a solidification material through a rotatable inner pipe or rotating shaft, which simplifies the system.

[0013] In the ground improvement mixing device of the present invention, the excavating and mixing member preferably has a connecting member that connects the upper extension member and a lower part of the outer pipe.

[0014] In this case, the anti-rotation blade is positioned between the excavating member and the agitating blade in the vertical direction, and the excavating / agitating member that does not interfere with the anti-rotation blade can be easily installed using the connecting member.

[0015] In addition, in the ground improvement mixing device of the present invention, it is preferable to provide a detection means that is provided at the upper part of the inner pipe in a portion exposed from the outer pipe and that detects the rotational torque acting on the inner pipe.

[0016] The shear force of the soil being stirred by the mixing blades acts as a rotational torque on the anti-rotation blades. Therefore, by detecting the rotational torque acting on the anti-rotation blades via the rotational torque acting on the inner pipe with a detection means provided on the part exposed from the outer pipe, it becomes possible to easily determine whether the co-rotation phenomenon is occurring. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional view showing a ground improvement mixing device according to an embodiment of the present invention. [Figure 2] Enlarged view of the bottom of Figure 1. [Figure 3] 10 is a graph showing an example of the relationship between time, the detected value of the rotation sensor, and the depth. DETAILED DESCRIPTION OF THE INVENTION

[0018] A ground improvement mixing device 100 according to an embodiment of the present invention will be described with reference to Figures 1 and 2. The ground improvement mixing device 100 mainly comprises an inner pipe 10, an outer pipe 20, an excavating and mixing member 30, a co-rotation prevention blade 40, and a detection means 50. The inner pipe 10 and the outer pipe 20 form a double pipe structure.

[0019] The number of inner pipes 10 and outer pipes 20 connected in the vertical direction corresponds to the depth of the excavated hole. An anti-corotation blade 40 is provided at the bottom of the lowest inner pipe 10, an excavating / stirring member 30 is provided at the bottom of the lowest outer pipe 20, and a detection means 50 is provided at the top of the highest inner pipe 10. However, there may be only one inner pipe 10 and one outer pipe 20 each.

[0020] The ground improvement mixing device 100 is installed in a construction machine, such as a pile driver or a small pile driver, used in a single-shaft mechanical mixing method (not shown). The construction machine includes a rotating shaft that rotates the outer pipe 20, a mechanism for rotating the rotating shaft, a mechanism for raising and lowering the rotating shaft, a leader and mast, heavy machinery for supporting the leader and mast, plant equipment capable of producing and storing a solidification material such as cement milk, and a supply means for supplying the solidification material from the plant equipment. Note that instead of the solidification material, a liquid such as water or a slurry-like material other than a solidification material may be supplied.

[0021] The inner pipe 10 is a cylindrical member extending vertically. The upper part of the inner pipe 10 is fixed to a member that is provided on the leader of the construction machine so as to be able to ascend and descend, and is configured so as not to be able to rotate.

[0022] Then, the solidification material is supplied into the inner pipe 10 by the aforementioned supply means through a supply port 11 formed at the upper end of the inner pipe 10. Then, this solidification material is discharged to the outside from a discharge port 12 formed at the tip of the inner pipe 10. The tip of the lowest inner pipe 10 is located inside a through-hole formed in an excavation member 31, which will be described later, and the solidification material is discharged into the soil excavated by the excavation member 31.

[0023] The outer pipe 20 is a circular tubular member that coaxially surrounds the outer periphery of the inner pipe 10 and is rotatable relative to the fixed inner pipe 10. Although not shown in detail, the outer pipe 20 has an upper portion fixed by a gripping member to a rotatable rotation shaft of a drive unit 21 that is mounted on the leader of the construction machine so that it can be raised and lowered. This makes the outer pipe 20 rotatable. The outer pipe 20 may be a square pipe or a rectangular pipe, for example.

[0024] The drilling and stirring member 30 here is composed of a drilling member 31, a lower boss 32, an upper boss 33, an upper extension member , a connecting member 35, and a stirring blade .

[0025] The drilling member 31 is provided at the lower end of the drilling and stirring member 30. A plurality of drilling bits 31a are fixed to the drilling member 31 by welding or the like.

[0026] The lower boss 32 is disk-shaped and is fixed by welding or the like to the upper part of the excavation member 31. A through hole that passes through in the vertical direction is formed in the center of the lower boss 32, and this through hole is configured to communicate with a through hole that is formed in the excavation member 31 and through which the inner pipe 10 is inserted.

[0027] The upper boss 33 is a thick, disk-shaped member having a hexagonal shaft 33a at its upper end and fixed by spline fitting to the lower end of the outer tube 20. A through-hole penetrating vertically is formed in the center of the upper boss 33, and this through-hole is configured to communicate with a through-hole formed in the outer tube 20, through which the inner tube 10 is inserted.

[0028] The upper extension member 34 extends upward from the radially outer portion of the drilling member 31. Here, the upper extension member 34 extends vertically upward from the radially outer end of the drilling member 31. However, the upper extension member 34 is not limited to this, and may have a base end located inside the radially outer end of the drilling member 31, or may extend obliquely upward in a straight or curved manner rather than vertically. Here, the shape of the upper extension member 34 is flat, but is not limited to this.

[0029] The connecting member 35 extends from the upper part of the upper extension member 34 and is connected to the outer pipe 20 via the upper boss 33. Here, the connecting member 35 extends horizontally from the upper end of the upper extension member 34. However, the connecting member 35 is not limited to this, and may have a base end below the upper end of the upper extension member 34, or may extend obliquely in a straight or curved manner rather than horizontally. It is preferable that the connecting member 35 be inclined upward toward the inside in the radial direction, since this makes it difficult for the mixed soil to rest on the upper surface of the connecting member 35. Here, the shape of the connecting member 35 is flat, but is not limited to this. The connecting member 35 also functions as a stirring member for stirring the excavated soil.

[0030] The agitator blade 36 is configured to extend horizontally from the vertical middle of the inner surface of the upper extension member 34 toward the inner pipe 10 to the vicinity of the inner pipe 10. However, the agitator blade 36 is not limited to extending horizontally, and may extend obliquely in a straight or curved manner. The agitator blade 36 is located above the excavation member 31. Two agitator blades 36 are formed here, extending in opposite directions at 180° from each other.

[0031] In addition, the agitating blades 36 are formed at the same height position from the center of the upper extension member 34. However, the position at which the agitating blades 36 are formed is not limited to this. For example, the agitating blades 36 may be formed at a position shifted in the vertical direction from the center of the upper extension member 34, and the height positions at which multiple agitating blades 36 are formed may be different. Furthermore, multiple agitating blades 36 may be formed at different height positions on one upper extension member 34.

[0032] Here, each agitator blade 36 has a T-shaped cross section consisting of a rectangular flat plate extending vertically and a rectangular flat plate extending horizontally located at the upper end of this flat plate. However, the shape of the agitator blade 36 is not limited to this, and may be a simple flat plate, an inclined flat plate, a curved plate, or any of various conventional shapes.

[0033] The stirring blade 36 has a radial length that is smaller than that of the drilling member 31. This prevents the stirring blade 36 from interfering with the inner pipe 10 and a boss 41 (described later) when the stirring blade 36 rotates in accordance with the rotation of the drilling / stirring member 30.

[0034] The anti-rotation blade 40 here protrudes from a cylindrical boss 41 fixed to the outer circumferential surface of the inner pipe 10 by welding or the like. The anti-rotation blade 40 is non-rotatable, just like the inner pipe 10. The anti-rotation blade 40 here is located midway between the excavation member 31 and the mixing blade 36 in the vertical direction. The radial length of the anti-rotation blade 40 is shorter than that of the excavation member 31. This prevents interference between the rotating excavation / mixing member 30 and the anti-rotation blade 40.

[0035] Here, the anti-rotation blades 40 are configured to extend horizontally radially outward to the vicinity of the upper extension member 34 at the vertical midpoint between the excavation member 31 and the agitator blade 36, and at the vertical midpoint between the agitator blade 36 and the connecting member 35. Here, two anti-rotation blades 40 are formed at each position, extending in opposite directions by 180°. Note that the agitator blade 36 and the anti-rotation blade 40 are not limited to two blades with an angle of 180° between the blades, but may be three blades with an angle of 120° between the blades, four blades with an angle of 90° between the blades, or a single blade. Furthermore, the number of blades in the agitator blade 36 and the anti-rotation blade 40 may be the same or different.

[0036] Here, two anti-rotation blades 40 are formed at different height positions. However, the positions at which the anti-rotation blades 40 are formed are not limited to this. For example, they may be formed at different positions between the excavation member 31 and the mixing blade 36 in the vertical direction, or they may be formed at different positions between the mixing blade 36 and the connecting member 35 in the vertical direction.

[0037] Here, each anti-rotation vane 40 is composed of a rectangular flat plate extending in the vertical direction. However, the shape of the anti-rotation vane 40 is not limited to this, and it may be an inclined flat plate, curved, or may have the same shape as various conventional anti-rotation vanes that rotate relative to one another.

[0038] The anti-rotation blade 40 has a radial length that is smaller than that of the excavating member 31. This prevents the anti-rotation blade 40 from interfering with the inner wall surface of the excavation hole. In addition, there is a gap between the anti-rotation blade 40 and the inner surface of the extension member 34 of the rotating excavating / stirring member 30. This prevents interference between the excavating / stirring member 30 and the anti-rotation blade 40.

[0039] The boss 41 is sandwiched vertically between the lower boss 32 and the upper boss 33 of the excavating / stirring member 30, thereby positioning the anti-rotation blade 40 vertically relative to the excavating / stirring member 30.

[0040] The detection means 50 is provided at the top of the inner pipe 10, at a portion where the inner pipe 10 is exposed from the outer pipe 20. The detection means 50 is a rotational torque sensor that detects the rotational torque (torsion moment) acting on the inner pipe 10. Here, the rotational torque sensor 50 is installed on a member that is provided at the upper end of the inner pipe 10 so as not to block the supply port 11 of the inner pipe 10 and that can raise and lower the leader of the construction machine. This rotational torque sensor 50 makes it possible to detect the rotational torque acting on the anti-corotation vane 40 via the rotational torque acting on the inner pipe 10.

[0041] According to the above-described ground improvement mixing device 100 of the embodiment of the present invention, the phenomenon of the soil excavated by the excavation member 31 rotating together with the mixing blade 36 is prevented by the fixed anti-rotation blade 40.

[0042] Furthermore, compared to the first co-rotation prevention technology described above, there is no need to provide a mechanism for rotating the inner pipe 10. Furthermore, since the solidification material can be supplied from the supply port 11 at the upper end of the fixed inner pipe 10, there is no need to provide a mechanism such as a swivel mechanism required to supply the solidification material via the rotating inner pipe or rotation shaft described above. These features make it possible to simplify the system.

[0043] Furthermore, compared to the second anti-rotation technology described above, there is no need to dig the horizontal end of the anti-rotation wing 40 into the inner wall of the excavation hole in order to fix it, which reduces the risk of damage to the anti-rotation wing 40.

[0044] Furthermore, the presence or absence of the co-rotation phenomenon may be determined by an operator or a detection value monitoring means such as a computer based on the detection value detected by the rotation torque sensor 50. The rotation torque acting on the co-rotation prevention impeller 40 is detected by the rotation torque sensor 50, and this rotation torque includes the shear force of the soil being mixed by the mixing impeller 36.

[0045] Therefore, for example, as shown in the graph in Figure 3, if the detected rotational torque value rises abnormally and an abnormal value is generated when the soil improvement mixing device 100 is pulled out, it can be assumed that a co-rotation phenomenon has occurred. In this case, since there is a risk that an inhomogeneous solidified mass will be created and the desired quality will not be achieved, it is preferable to immediately re-construct the work. Note that, as shown in Figure 3, after the excavation hole is excavated to the bottom, the soil improvement mixing device 100 is once slightly raised. This is to prevent the mixed soil near the bottom end from being insufficiently mixed, since it is only mixed by the lower mixing blades 36.

[0046] Furthermore, since the rotational torque sensor 50 is installed at the top of the inner pipe 10 and is located on the ground, it can be easily linked to a management device mounted on the construction machine via wired or wireless communication, enabling real-time monitoring.

[0047] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the claims. For example, the configuration of the excavating / stirring member 30 is not limited to that described above. The excavating / stirring member 30 can have any configuration as long as the anti-rotation blade 40 is positioned between the excavating member 31 and the stirring blade 36 in the vertical direction and does not interfere with the anti-rotation blade 40. [Explanation of symbols]

[0048] 10...inner pipe, 11...supply port, 12...discharge port, 20...outer pipe, 21...drive device, 30...drilling / mixing member, 31...drilling member, 31a...drilling bit, 32...lower boss, 33...upper boss, 33a...hexagonal shaft, 34...upper extension member, 35...connecting member, 36...mixing blade, 40...anti-co-rotation blade, 41...boss, 50...detection means, rotational torque sensor, 100...ground improvement mixing device.

Claims

1. an inner tube extending in the vertical direction; an outer tube that is rotatable relative to the inner tube, the outer tube being coaxial with the inner tube and surrounding the outer periphery of the inner tube; An excavation / stirring member is provided at the lower end of the outer pipe, and includes an excavation member provided at the lower end, an upper extension member extending upward from the radially outer portion of the excavation member, and an agitation blade protruding from the inner surface of the upper extension member toward the inner pipe, and is provided at the lower end of the outer pipe and rotates as the outer pipe rotates; A ground improvement mixing device characterized by having a co-rotation prevention blade that protrudes from the inner pipe so as to be positioned between the excavation member and the mixing blade in the vertical direction, and has a gap between it and the rotating excavation / mixing member.

2. The inner pipe has a supply port at its upper end through which a liquid or slurry material is supplied and a discharge port at its lower end through which the liquid or slurry material is discharged, and the tip of the inner pipe is located inside the through hole formed in the excavation member.

3. 2. The ground improvement mixing device according to claim 1, wherein the excavation and mixing member has a connecting member that connects the upper extension member and the lower part of the outer pipe.

4. 2. The ground improvement mixing device according to claim 1, further comprising a detection means provided at the upper part of the inner pipe in a portion exposed from the outer pipe, for detecting the rotational torque acting on the inner pipe.

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