Ground improvement mixing method and its apparatus

Abstract

After excavation of the excavation hole, crushing of the excavated soil and mechanical stirring and mixing of the crushed soil and the ground improvement material can be efficiently performed within the cylinder. 【Solution means】After excavation of the excavation hole by the lower excavation stirring blade 6, crushing of the excavated soil by the ring inner stirring blade 7 and mechanical stirring and mixing of the crushed soil and the ground improvement material can be efficiently performed within the stirring and mixing region ring 5. Therefore, the stirring and mixing of the ground improvement material and the excavated soil can be made uniform, and good-quality ground improvement can be achieved. From the discharge hole 22, the ground improvement material is jetted in a linear and / or planar shape, upward, horizontally, and downward at high pressure toward the inside of the stirring and mixing region ring 5 to finely crush the ground improvement soil and enhance the stirring effect.

Description

Technical Field

[0001] The present invention relates to a ground improvement mixing method and apparatus for mixing a ground improvement material and excavated soil within a cylinder. More specifically, the present invention relates to a ground improvement mixing method and apparatus for mixing excavated soil and a ground improvement material within a cylindrical rotating mixing region ring in a single-shaft ground improvement mixing apparatus.

Background Art

[0002] Although various methods have been proposed for ground improvement, a method is known in which an excavation hole is formed in the ground, a ground improvement material such as cement is injected into the excavated soil of the excavation hole, and the mixture is solidified by mixing with a stirring blade to form a ground improvement column such as a pile. During construction, in particular, the stirring blade and the improved soil may become integrated and rotate together in a lump. To prevent this co-rotation, a method is also known in which a co-rotation prevention blade that can freely rotate with a bearing on a drive shaft is provided, and this co-rotation prevention blade is fixed to the wall surface of the excavation hole during construction.

[0003] Under such circumstances, when mixing and stirring a ground improvement material and excavated soil with a stirring blade, in order to improve the stirring effect and prevent co-rotation, a method has been proposed in which a non-rotating cylindrical steel pipe (cylindrical body) is moved along the hole wall of the excavation hole while mixing and stirring inside this steel pipe (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in conventional cylindrical steel pipes, where soil improvement materials and excavated soil are mixed using mixing blades, when improving soil that is viscous and clayey and contains moisture, the soil may form lumps and rotate together, even with the anti-rotation blades. Soil improvement work on such soil can lead to interruptions in work to remove the lumps, uneven mixing, and a decline in the quality of the soil improvement work.

[0006] In view of the above background, the present invention achieves the following objects. The object of the present invention is to provide a ground improvement mixing method and device that can prevent the formation of lumps of excavated soil by injecting a ground improvement material at high pressure and finely pulverizing it simultaneously with mechanical mixing in the ground improvement of an excavated hole. Another object of the present invention is to provide a ground improvement mixing method and an apparatus therefor, which can efficiently crush excavated soil after excavating a hole, and mechanically mix and mix the crushed soil with ground improvement material within a cylinder. Yet another object of the present invention is to provide a ground improvement mixing method and device which can homogenize the mixing of ground improvement material and excavated soil to achieve high-quality ground improvement. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention takes the following measures. The ground improvement mixing method of the present invention 1 is a ground improvement device that is rotated by a rotary drive device for excavating the ground to excavate a hole, mixing the excavated soil with a ground improvement material, and performing ground improvement in the hole, and includes a single shaft having a tip bit for drilling ground at its lower end, a mixing blade that is fixed to the single shaft and mixes the excavated soil and the ground improvement material in the hole, and a co-rotation prevention blade that is rotatably attached to the single shaft, the outer peripheral end of which engages with the peripheral wall of the hole to stop rotation, and rotates relative to the rotation of the mixing blade and the tip bit to mix and mix the excavated soil together with the ground improvement material, A cylindrical stirring and mixing area ring is fixed to the single shaft at a position lower than the stirring blade and the anti-rotation blade and higher than the tip bit, and rotates together with the single shaft. At the lowermost position within the stirring and mixing area ring, a lower-stage excavation stirring blade is fixed to the single shaft and has a bit for excavation to excavate the excavation hole. Within the stirring and mixing area ring, a ring inner stirring blade is fixed to the single shaft at a position above the lower-stage excavation stirring blade to crush the excavated soil and stir and mix the excavated soil and the ground improvement material. The ground improvement material is at 5 to 30 MPa disposed with discharge holes on the single shaft for jetting and the stirring and mixing area ring has a friction reducing plate for reducing the friction on the inner peripheral surface of the excavation hole on the outer periphery and a bit for excavation arranged at the lower end By doing so, within the stirring and mixing area ring, the ground improvement material is jetted from the discharge holes to the ground excavated by the lower-stage excavation stirring blade, and the ground and the ground improvement material are stirred and mixed by the ring inner stirring blade.

[0008] The ground improvement stirring method of the second invention of the present invention is the same as that of the first invention ground improvement stirring method wherein the jetting of the ground improvement material from the discharge holes is characterized in that it is jetted in a linear and / or planar shape in one or more directions selected from the upward, lateral, and downward directions. The ground improvement stirring device of the present invention 1 is rotationally driven by a rotational drive device for excavating the ground to form an excavation hole, mixing the excavated soil and the ground improvement material, and performing ground improvement within the excavation hole. It includes a single shaft having a tip bit for ground boring at the lower end, a stirring blade fixed to the single shaft for stirring the excavated soil and the ground improvement material within the excavation hole, and an anti-rotation blade rotatably provided on the single shaft, with the outer peripheral end engaging with the peripheral wall of the excavation hole to stop rotation, and relatively rotating with the rotation of the stirring blade and the tip bit to mix and stir the excavated soil with the ground improvement material. In the ground improvement device, a cylindrical stirring and mixing area ring is fixed to the single shaft at a position lower than the stirring blade and the anti-rotation blade and higher than the tip bit, and rotates together with the single shaft; At the lowermost position within the stirring and mixing area ring, a lower-stage excavation stirring blade fixed to the single shaft, with a plurality of bits for excavation arranged in the diameter direction of the excavation hole; Within the stirring and mixing area ring, at an upper position of the lower-stage excavation stirring blade, a ring inner stirring blade fixed to the single shaft, for crushing the excavated soil excavated by the lower-stage excavation stirring blade and for stirring and mixing the excavated soil and the ground improvement material; The ground improvement material within the stirring and mixing area ring at 5 to 30 MPa A discharge hole provided on the single shaft for injecting the ground improvement material and consists of The stirring and mixing area ring is characterized in that on the outer periphery, there is a friction reduction plate for reducing the friction with the inner peripheral surface of the excavation hole, and bits for excavation are arranged at the lower end. The present invention 2 The ground improvement stirring device of the present invention ground improvement stirring device of 1 In the present invention, the discharge hole injects the ground improvement material in one or more directions selected from the upward, lateral, and downward directions in a linear and / or planar shape. The present invention 3 The ground improvement stirring device of the present invention ground improvement stirring device of 1 or 2 In the present invention, the ring inner stirring blade S Is in a shape like the Chinese character "zi".

Advantages of the Invention

[0009] The ground improvement stirring method and its device of the present invention can efficiently perform the crushing of the excavated soil after excavation by the lower-stage excavation stirring blade and the mechanical stirring and mixing of the crushed soil and the ground improvement material within the stirring and mixing area ring. Therefore, the stirring and mixing of the ground improvement material and the excavated soil can be made uniform, and good-quality ground improvement can be achieved.

Brief Explanation of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

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Figure 5

Figure 6

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Figure 10

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the stirring head of the ground improvement stirring device according to the embodiment of the present invention will be described with reference to the drawings. Figure 1 is an overall perspective view showing the stirring head of the ground improvement stirring device according to the embodiment of the present invention, and is an overall perspective view seen from the lower end side. Figure 2 is an overall perspective view seen from the lower end side showing the state where the stirring head of Figure 1 is rotated 90 degrees counterclockwise, Figure 3 is an overall perspective view of the stirring head of Figure 2 as seen from the upper end side, and Figure 4 is an overall perspective view of the stirring head of Figure 3 rotated 90 degrees counterclockwise as seen from the upper end side. Figure 5 is a front view showing the stirring head of the ground improvement stirring device according to the embodiment of the present invention, Figure 6 is a view taken in the direction of arrow P of Figure 5, Figure 7 is a view taken in the direction of arrow Q of Figure 5, Figure 8 is a view taken in the direction of arrow R of Figure 5, and Figure 9 is a sectional view taken along line A-A of Figure 5. As shown in Figures 1 to 9, the stirring head 1 is mounted on a head (not shown) of a ground improvement machine body that can move on the ground and is rotationally driven.

[0012] The drive shaft (single shaft) 2 of the stirring head 1 is connected to a rotary drive device mounted on the head of the ground improvement machine main body and is rotationally driven. The ground improvement material pumped from the ground improvement machine main body is injected into the injection hole 21 at the upper end of the hollow drive shaft 2. The injected ground improvement material is discharged from the discharge hole 22 on the lower end side of the drive shaft 2 and is stirred with the excavated soil in the excavation hole. Three discharge holes 22 are formed at 120-degree intervals on the outer periphery near the lower end of the drive shaft 2, and the ground improvement material is sprayed simultaneously in the upward, horizontal, and downward directions at high pressure (5 to 30 MPa). A plurality of tip bits 24 for ground boring are fixed to the lower end portion (excavation hole bottom side) of the drive shaft 2.

[0013] An upper stirring blade 31 and a lower stirring blade 32 are integrally fixed to the upper part of the drive shaft 2 by welding or the like. The upper stirring blade 31 and the lower stirring blade 32 are spaced apart in the central axis direction (vertical direction) of the drive shaft 2 and are arranged with a phase difference of about 90 degrees. Further, the upper stirring blade 31 and the lower stirring blade 32 are attached so as to face each other 180 degrees on both sides in the radial direction of the drive shaft 2 in a direction orthogonal to the central axis of the drive shaft 2. Further, the upper stirring blade 31 and the lower stirring blade 32 are attached in a flat plate shape and intersect with the plane including the central axis of the drive shaft 2. For each of the upper stirring blade 31 and the lower stirring blade 32, one inclination direction in the radial direction is opposite to the other inclination direction in the radial direction. When the drive shaft 2 is rotationally driven (forward rotation), the upper stirring blade 31 and the lower stirring blade 32 lift the excavated soil upward while stirring it and push it downward to the bottom side of the excavation hole while stirring the excavated soil.

[0014] A co-rotation prevention blade 4 is rotatably attached to the drive shaft 2 below the lower stirring blade 32. The bearing portion 41 at the center of the co-rotation prevention blade 4 is rotatably supported by the upper and lower flange portions 23, 23 integral with the drive shaft 2. Flat plate-shaped wing bodies 42, 42 are fixed to the outer peripheral surface of the bearing portion 41 at positions facing each other 180 degrees by bolts. The wing bodies 42, 42 are attached so as to face each other 180 degrees on both sides in the radial direction of the drive shaft 2. Further, the wing bodies 42, 42 are attached parallel to the plane including the central axis of the drive shaft 2. Therefore, the co-rotation prevention blade 4 bites into the inner peripheral wall surface (not shown) of the excavation hole, and the co-rotation prevention blade 6 does not rotate even when the drive shaft 2 is rotationally driven.

[0015] On the drive shaft 2, a cylindrical stirring and mixing region ring 5 is fixed at a position below the anti-rotation preventing wing 4 and above the tip bit 24 by means of an S-shaped inner stirring wing 7 or the like. At a position below the fixed plate 51 and at the lowermost position of the stirring and mixing region ring 5 and above the tip bit 24, a lower excavation stirring wing 6 is integrally fixed to the drive shaft 2 by welding or the like. The lower excavation stirring wing 6 is attached in a direction orthogonal to the central axis of the drive shaft 2 and facing 180 degrees to both sides in the radial direction of the drive shaft 2. Further, the lower excavation stirring wing 6 is attached in a flat plate shape and intersects the plane including the central axis of the drive shaft 2. One inclination direction in the radial direction of the lower excavation stirring wing 6 is opposite to the other inclination direction in the radial direction. A plurality of bits 61 for excavating excavation holes are fixed to the lower excavation stirring wing 6 in the diameter direction of the excavation holes.

[0016] Friction reducing plates (for example, a pin plate with a plurality of carbide pins driven in) 62 for reducing the friction on the inner peripheral surface of the excavation holes are fixed to the outermost peripheral bits 61, 61 of the lower excavation stirring wing 6. The friction reducing plate 62 protrudes slightly outside the outer peripheral surface 54 of the stirring and mixing region ring 5. Since the friction reducing plate 62 protrudes slightly outside the outer peripheral surface 54 of the stirring and mixing region ring 5, the friction between the outer peripheral surface 54 of the stirring and mixing region ring 5 and the surrounding ground during the excavation of the excavation holes can be alleviated, and the ground outside the outer peripheral surface 54 can be loosened. The outer diameter dimension of the outer peripheral surface 54 of the stirring and mixing region ring 5 is the same as the rotational outer diameter of the upper stirring wing 31 and the lower stirring wing 32. Further, the rotational outer diameter of the anti-rotation preventing wing 4 is formed larger than the outer diameter dimension of the outer peripheral surface 54 of the stirring and mixing region ring 5.

[0017] Within the stirring and mixing area ring 5, at the upper position of the lower excavation stirring blade 6, an S-shaped in-ring stirring blade 7 is fixed to the drive shaft 2 and the inner peripheral surface 52 of the stirring and mixing area ring 5, crushing the excavated soil excavated by the lower excavation stirring blade 6 and stirring and mixing the excavated soil and the ground improvement material. Since the S-shaped in-ring stirring blade 7 is curved in the horizontal and vertical directions, the excavated soil can be stirred in the horizontal and vertical directions. Also, the in-ring stirring blade 7 has the effect of preventing deformation of the stirring and mixing area ring 5 due to earth pressure. The in-ring stirring blade 7 is attached at a right angle to the lower excavation stirring blade 6, but the attachment angle can be arbitrarily changed.

[0018] Since the stirring and mixing area ring 5 is fixed to the drive shaft 2, it rotates together with the drive shaft 2. However, a plurality of bits 53 for excavation are fixed at equal angular intervals on the circumference of the lower end of the stirring and mixing area ring 5, so the straightness is good and the excavation hole is kept vertical. Also, simultaneously with the mechanical stirring by the S-shaped in-ring stirring blade 7, the ground improvement material is injected at a high pressure (5 - 30 MPa) and pulverized, so that the excavated soil can be prevented from forming lumps. The injection angle of the ground improvement material injected upward from the discharge hole 22 is set so that it reaches near the upper end of the stirring and mixing area ring 5, and the injection angle of the ground improvement material injected downward is set so that it reaches near the lower end of the stirring and mixing area ring 5. It is desirable to change this injection angle according to the inner diameter dimension of the excavation hole (outer diameter dimension of the stirring and mixing area ring 5). Furthermore, since the crushing of the excavated soil by the lower excavation stirring blade 6 by the in-ring stirring blade 7 and the mechanical stirring and mixing of the crushed soil and the ground improvement material can be efficiently performed within the stirring and mixing area ring 5, the stirring and mixing of the ground improvement material and the excavated soil can be made uniform, and good-quality ground improvement can be achieved.

[0019] [Other examples of ground improvement materials] The above-described method of discharging the ground improvement material was to linearly inject the ground improvement material in one direction from a single discharge hole 22. The injection method of the ground improvement material of the present invention is not limited to this. The injection of the ground improvement material varies depending on the characteristics of the soft ground, the water content, the desired properties when solidified after construction, etc. In order to perform uniform ground improvement, it is necessary to prevent the formation of lumps during stirring. Figures 10(a) to (d) are schematic diagrams showing other examples of the method of discharging the ground improvement material. The injection method of the ground improvement material shown in Figure 10(a) is an example of simultaneously linearly injecting in three directions: obliquely upward, horizontally (laterally), and obliquely downward from a single discharge hole 22a provided on the drive shaft 2. The discharge holes 22a are arranged on the outer periphery of the drive shaft 2, and three are arranged at 120-degree angular intervals toward the inner periphery of the stirring and mixing region ring 5. The injection method of the ground improvement material shown in Figure 10(b) is an example that combines linear and planar (fan-shaped) injections. The discharge holes 22b inject linearly in two directions: obliquely upward and obliquely downward, but inject in a fan-shaped plane in the horizontal direction. The fan-shaped injection is performed by forming the shape of the discharge hole into a slit.

[0020] The injection method of the ground improvement material shown in Figure 10(c) is an example that combines linear and planar (fan-shaped) injections. The discharge hole 22c injects in a fan-shaped plane in the horizontal direction and linearly in the obliquely downward direction. The discharge holes 22c' at other angular positions inject only in a fan-shaped plane in the horizontal direction. The injection method of the ground improvement material shown in Figure 10(d) is an example that combines linear and planar (fan-shaped) injections. The discharge hole 22d injects in a fan-shaped plane in the obliquely upward direction and linearly in the obliquely downward direction. The discharge holes 22d' at other angular positions inject only in a fan-shaped plane in the oblique direction. As described in detail above, the injection from the discharge holes of the ground improvement material is optimized to be linear and / or planar in one or more directions selected from the upward, lateral, and downward directions according to the properties of the ground, etc.

Explanation of Signs

[0021] 1... Stirring head 2... Drive shaft (single shaft) 21... Injection hole 22... Discharge hole 23…Flange part 24…Tip bit 31…Upper stirring blade 32…Lower stirring blade 4…Anti-rotation wing 41…Bearing part 42…Wing body 5…Stirring and mixing area ring 51…Fixed plate 52…Inner peripheral surface 53…Bit for excavation 54…Outer peripheral surface 6…Lower excavation and stirring blade 61…Bit 62…Friction reduction plate (pin plate) 7…Inner-ring stirring blade

Claims

1. A single shaft having a tip bit for drilling ground at its lower end, which is rotated by a rotary drive device for excavating the ground to excavate a hole, mixing the excavated soil with a ground improvement material, and performing ground improvement in the excavated hole; A mixing blade fixed to the single shaft for mixing the excavated soil and the ground improvement material in the excavated hole; a co-rotation prevention blade that is rotatably provided on the single shaft, the outer peripheral end of which engages with the peripheral wall of the excavated hole to stop rotation, and rotates relative to the rotation of the mixing blade and the tip bit to mix and stir the excavated soil together with the ground improvement material; In the ground improvement device, A cylindrical stirring and mixing zone ring is fixed to the single shaft at a position lower than the stirring blade and the co-rotation prevention blade and above the tip bit, and rotates together with the single shaft; A lower drilling and mixing blade is disposed at the lowest position in the stirring and mixing area ring, the lower drilling and mixing blade is fixed to the single shaft, and has a drilling bit to drill the drilling hole; Within the stirring and mixing area ring, an inner-ring stirring blade is arranged which is fixed to the single shaft at an upper position of the lower-stage excavation stirring blade, and which crushes the excavated soil excavated by the lower-stage excavation stirring blade and stirs and mixes the excavated soil and the ground improvement material; A discharge hole is arranged on the single shaft to inject the ground improvement material into the stirring and mixing area ring at 5 to 30 MPa, The stirring and mixing area ring has a friction reduction plate on the outer periphery for reducing friction on the inner periphery of the drilling hole, and a drilling bit on the lower end. In the stirring and mixing area ring, the soil improvement material is injected from the discharge hole into the ground excavated by the lower excavation stirring blade, and the soil and the soil improvement material are stirred and mixed by the stirring blade inside the ring. A ground improvement mixing method characterized by the above.

2. In the ground improvement mixing method according to claim 1, The soil improvement material is sprayed from the discharge hole in a linear and / or planar manner in one or more directions selected from an upward direction, a lateral direction, and a downward direction. A ground improvement mixing method characterized by the above.

3. A single shaft having a tip bit for drilling ground at its lower end, which is rotated by a rotary drive device for excavating the ground to excavate a hole, mixing the excavated soil with a ground improvement material, and performing ground improvement in the excavated hole; A mixing blade fixed to the single shaft for mixing the excavated soil and the ground improvement material in the excavated hole; a co-rotation prevention blade that is rotatably provided on the single shaft, the outer peripheral end of which engages with the peripheral wall of the excavated hole to stop rotation, and rotates relative to the rotation of the mixing blade and the tip bit to mix and stir the excavated soil together with the ground improvement material; In the ground improvement device, A cylindrical stirring and mixing zone ring is fixed to the single shaft at a position lower than the stirring blade and the co-rotation prevention blade and above the tip bit, and rotates together with the single shaft; A lower drilling and mixing impeller is fixed to the single shaft at the lowest position in the stirring and mixing area ring, and a plurality of drilling bits are arranged in the diameter direction of the drilled hole; A ring-inner agitator is fixed to the single shaft at an upper position of the lower-stage excavation agitator in the agitation mixing area ring, and crushes the excavated soil excavated by the lower-stage excavation agitator and agitates and mixes the excavated soil and the ground improvement material; A discharge hole is provided on the single shaft for injecting the ground improvement material into the stirring and mixing area ring at 5 to 30 MPa, The stirring and mixing zone ring has a friction reduction plate on its outer periphery for reducing friction on the inner periphery of the drilled hole, and a drilling bit on its lower end. A ground improvement mixing device characterized by the above.

4. The ground improvement mixing apparatus according to claim 3, The discharge holes are configured to inject the ground improvement material linearly and / or planarly in one or more directions selected from an upward direction, a lateral direction, and a downward direction. A ground improvement mixing device characterized by the above.

5. The ground improvement mixing apparatus according to claim 3 or 4, The stirring blade in the ring is S-shaped. A ground improvement mixing device characterized by the above.

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