JP7764207B2 - Excavation and mixing equipment and deep mixing treatment method - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies. (1) February 17, 2021: Publication of a publication entitled "DG Column Method - Slurry-based Mechanically Agitated Deep Mixing Treatment Method - Quality and Construction Management Guidelines."

(2) March 6, 2021: Publication entitled "DG Column Method - Slurry-based Mechanically Agitated Deep Mixing Treatment Method - GBRC Performance Certification (No. 22-20)"

Article 30, Paragraph 2 of the Patent Act applies (3) April 14, 2021 Website https://www.gbrc.or.jp/ https://www.gbrc.or.jp/building_confirm/ https://www.gbrc.or.jp/building_confirm/gijyutu_ninsho/ https://www.gbrc.or.jp/search/gijyutu.php? Published at go_search=true&display_order=agent&display_sort=desc&page=9

(4) July 30, 2021: Publication of a publication entitled "NEW TECHNOLOGY TO SUPPORT PEACE OF MIND DG Column Method, Slurry-Based Mechanically Agitated Deep Mixing Treatment Method, Construction Technology Performance Certification/GBRC Performance Certification No. 20-22."

Article 30, Paragraph 2 of the Patent Act applies. (5) May 24, 2021. Published on the website https://www.daiwalantec.jp/index.html https://www.daiwalantec.jp/reinforcement/

Article 30, Paragraph 2 of the Patent Act applies (6) August 16, 2021 Website https://www.gbrc.or.jp/ https://www.gbrc.or.jp/building_confirm/ https://www.gbrc.or.jp/building_confirm/gijyutu_ninsho/ https://www.gbrc.or.jp/search/gijyutu.php? Published at go_search=true&display_order=agent&display_sort=desc&page=9

Article 30, Paragraph 2 of the Patent Act applies. (7) August 27, 2021: Publication entitled "DG Hybrid Method Explanatory Material"

(8) August 16, 2021: Publication of "DG Hybrid Construction Method: Explanatory Materials for Performance Certification" and "DG Hybrid Construction Method: Design and Construction Guidelines"

(9) October 25, 2021: Publication of a publication entitled "NEW TECHNOLOGY TO SUPPORT PEACE OF MIND DG Hybrid Method - Pile-shaped Ground Reinforcement Method Using Ground Improvement Bodies with Checkered Steel Pipes - Construction Technology Performance Certification/GBRC Performance Certification No. 21-06"

The present invention relates to an excavation and mixing device and a deep mixing method for constructing columns in the ground by mechanically mixing and stirring the slurry (cement milk), which is a mixture of cement-based solidification material and water, while injecting the slurry into the ground.

Deep mixing methods using excavation and mixing equipment have been used for some time. Deep mixing methods are used to improve the ground for structures such as buildings, structures, and retaining walls. They involve injecting a slurry made by mixing a cement-based solidification material with water into the ground, mechanically mixing and stirring the slurry and soil, and creating columns (columnar improvement bodies) in the ground. These columns reinforce the ground and support the structure. In this specification, "cement-based solidification material" refers to cement and other solidification materials whose main component is cement, used to solidify soil. These materials are also commonly referred to as "solidification materials." In this specification, "slurry" refers to a liquid made by mixing a cement-based solidification material with water, and is also commonly referred to as "cement milk."

For example, as disclosed in Japanese Patent Application Laid-Open No. 2019-214911 (Patent Document 1), Japanese Patent Application Laid-Open No. 2017-048616 (Patent Document 2), and Utility Model Registration No. 3215453 (Patent Document 3), conventional excavating and stirring devices are configured with a cylindrical rotating shaft, a drilling blade, a stirring blade, and a co-rotation prevention blade. A conduit for supplying slurry is formed inside the cylindrical rotating shaft, and the slurry is discharged into the ground from a slurry discharge hole formed at the tip of the rotating shaft. The drilling blade excavates the ground, and the excavated soil and slurry are mixed and stirred by the stirring blade. Furthermore, when the excavating and stirring device excavates and mixes the ground, the co-rotation prevention blade abuts against the wall of the excavated hole and remains stationary. When stationary, the co-rotation prevention blade prevents the soil and slurry being mixed and stirred from rotating together.

Japanese Patent Application Laid-Open No. 2019-214911 Japanese Patent Application Laid-Open No. 2017-048616 Utility Model Registration No. 3215453

With the conventional excavation and mixing equipment described above, when excavating and mixing the ground, the slurry is discharged into the ground using only the pressure of the pressure pump. As a result, the slurry does not spread throughout the entire column that is ultimately constructed, and unsolidified soil lumps become mixed into the column, resulting in inconsistent column strength.

Furthermore, conventional excavation and mixing equipment was equipped with anti-rotation blades, but these were unable to remove lumps of soil that had adhered to the blades. In other words, as the excavation and mixing equipment continued to excavate and mix the ground, soil would adhere to the blades over time, forming lumps, causing the blades and soil lumps to rotate together. This co-rotation phenomenon resulted in insufficient mixing of the slurry and soil by the blades, and the resulting column lacked strength.

Furthermore, with conventional excavation and mixing equipment, problems such as insufficient spreading of the slurry and co-rotation could occur simultaneously, making it difficult to consistently build columns of the required quality.

The present invention was made in consideration of the above-mentioned problems, and aims to provide an excavation and mixing device and deep mixing method that can spread slurry throughout the entire column that is ultimately constructed and effectively prevent co-rotation, thereby enabling the construction of high-quality columns with consistent strength.

(1) In order to achieve the above-mentioned object, the excavating and mixing apparatus of the present invention is an excavating and mixing apparatus for constructing columns in the ground by mechanically mixing and mixing a slurry, which is a mixture of cement-based solidification material and water, while injecting the slurry into the ground. The excavating and mixing apparatus comprises: a cylindrical rotating shaft having an internal conduit for supplying the slurry into the ground and a slurry discharge hole at its tip that communicates with the conduit; an excavating blade fixed to the tip of the rotating shaft and having an excavation claw attached to it for excavating the ground; an mixing blade fixed to a portion of the rotating shaft other than the tip and for stirring the ground; an anti-rotation blade fixed to a boss rotatably attached to the outside of a portion of the rotating shaft other than the tip and which does not transmit the rotation of the rotating shaft by the boss; and a nozzle attached to the slurry discharge hole of the rotating shaft, having an internal flow path for the slurry that decreases in diameter from the inlet to the outlet, and for accelerating the flow of the slurry and spraying it into the ground.

(2) Preferably, in the drilling and stirring device of (1) above, two or more slurry discharge holes are formed at the tip of the rotating shaft, and the nozzle is attached to each of the two or more slurry discharge holes.

(3) Preferably, in the drilling and stirring device described in (1) or (2) above, the nozzle outlet has a diameter of 5 mm to 25 mm, and the nozzle is detachably attached to the slurry discharge hole.

(4) Preferably, in any of the excavating and mixing devices described above in (1) to (3), a nozzle cover is provided at the tip of the rotating shaft to prevent soil from covering the nozzle when the rotating shaft is rotated in one direction.

(5) Preferably, in any of the above (1) to (4) drilling and stirring devices, three or four pairs of stirring blades are provided, and the stirring blades of each set are fixed symmetrically at different positions on the rotating shaft other than the tip.

(6) Preferably, in any of the excavating and stirring devices (1) to (5) above, a blade extending vertically is fixed to the boss to which the anti-rotation blade is fixed.

(7) Preferably, in the excavating and stirring device of (6) above, the anti-rotation blade is approximately U-shaped or approximately Y-shaped, and has two or three bosses for fixing two or three ends of the anti-rotation blade, respectively, and the blade is fixed to at least one of the bosses.

(8) In order to achieve the above-mentioned object, the deep mixing method of the present invention is a deep mixing method that uses any of the excavation and stirring devices described above in (1) to (7) to construct a column in the ground by mechanically mixing and stirring the slurry and soil while injecting a slurry obtained by mixing a cement-based solidification material with water into the ground, and by rotating the excavation and stirring device in one direction and spraying the slurry from the nozzle while moving it through the ground, excavating the ground from the position where the head of the column will be formed to the position where the tip of the column will be formed, and The process includes the steps of mixing and stirring the slurry and soil, stopping the spraying of the slurry from the nozzle and holding the excavating and stirring device in a position where the tip of the column will be formed until a predetermined time has elapsed, and, after the predetermined time has elapsed, retracting the excavating and stirring device approximately the height of the excavating and stirring device while rotating it in the opposite direction, advancing the excavating and stirring device to a position where the tip of the column will be formed while rotating it in one direction, and retracting the excavating and stirring device to a position where the head of the column will be formed while rotating it in the opposite direction.

(9) In order to achieve the above-mentioned object, the deep mixing treatment method of the present invention is a deep mixing treatment method that uses any of the excavation and stirring devices described above in (1) to (7) to construct a column in the ground by injecting a slurry obtained by mixing a cement-based solidification material with water into the ground and mechanically mixing and stirring the slurry and soil, and includes the steps of: rotating the excavation and stirring device in one direction while moving it through the ground to excavate the ground to an arbitrary position between the position where the head of the column is to be formed and the position where the tip of the column is to be formed; continuing to rotate the excavation and stirring device in one direction while spraying the slurry from the nozzle while moving it through the ground to excavate the ground from the arbitrary position to the position where the tip of the column is to be formed and mixing and stirring the slurry and soil; stopping the spraying of the slurry from the nozzle and stopping the spraying of the slurry from the nozzle for a predetermined time; the excavation and stirring apparatus is held at a position where the tip of the column is to be formed until a predetermined time has elapsed; after the predetermined time has elapsed, the excavation and stirring apparatus is rotated in the reverse direction while being retracted approximately the height of the excavation and stirring apparatus; the excavation and stirring apparatus is rotated in one direction while advancing to a position where the tip of the column is to be formed; the excavation and stirring apparatus is rotated in the reverse direction while being retracted to a position where the head of the column is to be formed; the excavation and stirring apparatus is rotated in one direction and the slurry is sprayed from the nozzle while advancing through the ground, thereby mixing and stirring the slurry and soil from the position where the head of the column is to be formed to the arbitrary position; and the steps of stopping the spray of the slurry from the nozzle and retracting the excavation and stirring apparatus from the arbitrary position to the position where the head of the column is to be formed while rotating in the reverse direction.

(10) Preferably, in the deep mixing method described in (8) or (9) above, the slurry and soil are mixed and stirred from the position where the head of the column is to be formed to the position where the tip of the column is to be formed, and after the excavation and stirring device is raised from the ground, a checkered steel pipe is inserted into the mixed and stirred slurry and soil, thereby constructing the column integrated with the checkered steel pipe in the ground.

In the excavation and mixing equipment and deep mixing method of the present invention, slurry is injected into the ground at a higher-than-normal pressure using a nozzle attached to the slurry discharge hole. This allows the slurry to be dispersed throughout the entire column that will ultimately be constructed. In addition, a blade attached to the boss of the anti-rotation blade can remove lumps of soil that have adhered to the mixing blade, effectively preventing the co-rotation phenomenon. These synergistic effects make it possible to construct high-quality columns with consistent strength.

1 is a front view showing an excavating and stirring apparatus according to a first embodiment of the present invention. FIG. FIG. 2 is a right side view showing the drilling and stirring device according to the first embodiment. Figure 3(a) is an enlarged view of the tip of the excavating and stirring apparatus of Figure 1. Figure 3(b) is a cross-sectional view taken along line A-A in Figure 3(a). Figure 3(c) is a front view showing a nozzle provided at the tip of the excavating and stirring apparatus. Figure 3(d) is a right side view showing the nozzle. Figure 3(e) is a cross-sectional view showing the nozzle. FIG. 4 is a front view showing a drilling and stirring apparatus according to a second embodiment of the present invention. 1 is a schematic diagram showing a deep mixing treatment method according to a first embodiment of the present invention. FIG. FIG. 10 is a schematic diagram showing the first half of a deep mixing treatment method according to a second embodiment of the present invention. FIG. 10 is a schematic diagram showing the second half of the deep mixing treatment method according to the second embodiment. FIG. 10 is a schematic diagram showing a deep mixing treatment method according to a third embodiment of the present invention. 10 is a schematic diagram showing the main parts of a modified example of the excavating and stirring device of the present invention. FIG.

1. First Embodiment of Excavating and Stirring Apparatus A first embodiment of the excavating and stirring apparatus of the present invention will be described with reference to FIGS. 1 to 3. FIG.

As shown in Figures 1 and 2, the excavating and mixing device 1 is primarily composed of a rotating shaft 10, an excavating blade 20, an mixing blade 30, a co-rotation prevention blade 40, and a blade 50.

1.1 Rotating Shaft As shown in Figures 1, 2, and 3(b), the rotating shaft 10 is a cylindrical member having an internal conduit 10a. A slurry 100 (see Figures 5 to 7), which is a mixture of a cement-based solidification material and water, is supplied to this conduit 10a. A grout pump (not shown) is used to supply the slurry 100. For example, the diameter of the rotating shaft 10 is 139 mm, and the overall length is 883 mm.

Two slurry discharge holes 10b that communicate with the conduit 10a are formed at the tip of the rotating shaft 10. The two slurry discharge holes 10b are arranged at symmetrical positions at the tip of the rotating shaft 10. The slurry discharge holes 10b are circular, and have a female thread formed on their inner circumferential surface. For example, the inner diameter of the slurry discharge hole 10b is 36 mm. The nozzles 60, described below, are replaceably attached to the two slurry discharge holes 10b with screws.

The excavating and stirring device 1 of this embodiment can select either two or one slurry discharge holes 10b for discharging the slurry 100, depending on the amount of slurry required for ground improvement. When two slurry discharge holes 10b are used, a nozzle 60 is attached to each of the two slurry discharge holes 10b. On the other hand, when one slurry discharge hole 10b is used, a nozzle 60 is attached to one of the slurry discharge holes 10b, and a bolt (not shown) is screwed into the other slurry discharge hole 10b to close the other slurry discharge hole 10b.

A joint 11, shown in Figures 1 and 2, is fixed to the rear end of the rotating shaft 10. A conduit (not shown) is formed inside the joint 11, and slurry 100 is supplied from this conduit to the conduit 10a of the rotating shaft 10. The rotating shaft 10 is connected to a rod 80 (see Figures 5 to 7) of a construction machine (not shown) via the joint 11. For example, the maximum diameter of the rod 80 is approximately the same as that of the rotating shaft 10, and the total length is 3 to 6 m.

1.2 Excavation Blades As shown in FIG. 2, the excavation and stirring device 1 includes two excavation blades 20. The two excavation blades 20 are fixed at positions symmetrical to each other at the tip of the rotating shaft 10. Two first excavation claws 21 are attached to the inner side in the longitudinal direction of each excavation blade 20. Furthermore, one cutting claw 23 is attached to the outer side in the longitudinal direction of each excavation blade 20. Furthermore, two second excavation claws 22 are fixed vertically to the tip surface of the rotating shaft 10. For example, the total length of one excavation blade 20 is 330 mm. The total diameter of the two excavation blades 20 and the diameter of the rotating shaft 10 forms an excavated hole in the ground with a diameter of approximately 800 mm.

1.3 Stirring Blades As shown in Figures 2 and 3, the excavating and stirring device 1 has three sets of two stirring blades 30, for a total of six stirring blades 30. All six stirring blades 30 are fixed to the rotating shaft 10 closer to the rear end than the drilling blades 20. The sets of two stirring blades 30 are arranged symmetrically to each other on the rotating shaft 10. Of the three sets of stirring blades 30 arranged at the top, middle, and bottom of the rotating shaft 10, the middle set of stirring blades 30 is arranged 90° shifted from the two sets of stirring blades 30 above and below. Each set of stirring blades 30 arranged on the rotating shaft 10 is attached with one lifting claw 31. The lifting claw 31 is arranged on the outer side of the stirring blade 30 in the longitudinal direction. For example, the total length of one stirring blade 30 is 330 mm, the same as the drilling blade 20.

1.4 Rotation Prevention Wings As shown in FIG. 1 , the excavating and stirring device 1 includes a set of two rotation prevention wings (free wings) 40. Each rotation prevention wing 40 is roughly U-shaped, with two horizontal sections connected by one vertical section. The ends of the two horizontal sections of the rotation prevention wing 40 are fixed to two bosses 41, respectively. Each of the two bosses 41 is rotatably attached to two collars 42 attached to the outside of the rotating shaft 10. The bosses 41 are configured to be able to rotate freely while contacting the outer surfaces of the collars 42. This prevents the rotation of the rotating shaft 10 and the collars 42 from being transmitted to the rotation prevention wing 40. By constructing the collars 42 from wear-resistant steel plate, wear due to contact with the rotation prevention wing 40 is reduced.

Each anti-rotation blade 40 is composed of two horizontal sections, one above the other, extending horizontally, and one vertical section connected to these two horizontal sections. For example, the horizontal projection length of one anti-rotation blade 40 from the rotation axis 10 to the vertical section is 430 mm, which exceeds the overall length of the excavating blades 20 and mixing blades 30. The vertical section of the anti-rotation blade 40 abuts against the wall of the excavation hole when the excavating and mixing device 1 excavates and mixes the ground. This keeps the anti-rotation blade 40 stationary. The soil and slurry 100 mixed and mixed by the mixing blade 30 come into contact with the horizontal section of the stationary anti-rotation blade 40, preventing the soil and slurry 100 from rotating together.

2, the excavation and mixing device 1 is equipped with two blades 50. The two blades 50 are fixed to the two bosses 41 to which the anti-rotation blades 40 are attached. The blades 50 have a plate surface extending vertically, and this plate surface can be brought into contact with and remove lumps of soil adhering to the mixing blades 30.

1.6 Nozzle As shown in Figures 3(a) and 3(b), two nozzles 60 are interchangeably attached to the two slurry discharge holes 10b at the tip of the rotating shaft 10. The present invention is based on a conventional deep mixing method using a mechanical agitation system that uses a cement-based solidification slurry 100. The nozzle 60 attached to the slurry discharge port 10b sprays the slurry 100 at a higher pressure than usual. Spraying the slurry 100 from the nozzle 60 promotes mixing and agitation of the soil and the slurry 100, ensuring that the slurry 100 is thoroughly dispersed throughout the entire column that is ultimately constructed. This enables the construction of high-quality columns with minimal variation in strength.

As shown in Figures 3(c) to 3(e), the nozzle 60 in this embodiment is composed of a hexagonal head 61, a male threaded portion 62 for threading into the female threaded portion of the slurry discharge outlet 10b, and a tapered flow path 63 that accelerates the flow of the slurry 100. The outlet 63b of the nozzle 60 has a smaller diameter than the inlet 63a.

The diameter of the nozzle 60 outlet 63b is determined by the number of nozzles 60 used and the amount of slurry 100 discharged per unit time, and is, for example, within the range of 5 mm to 25 mm. Specific examples of the diameter of the nozzle 60 outlet 63b, the number of nozzles 60, and the drilling/agitating blade diameter when discharging 50 to 500 liters of slurry 100 per minute are shown in Table 1 below. The drilling/agitating blade diameter is the sum of the overall length of one set of drilling blades 20 or agitating blades 30 and the diameter of the rotating shaft 10. For example, the drilling/agitating blade diameter in this embodiment is 330 mm + 330 mm + 139 mm ≒ 800 mm.

As shown in Figures 3(a) and (b), nozzle covers 70 corresponding to each of the two nozzles 60 are provided at the tip of the rotating shaft 10. The nozzle covers 70 are semicircular walls with a diameter that covers the nozzles 60, and are arranged in the forward rotation direction of the rotating shaft 10 shown in Figure 3(b). When the rotating shaft 10 is rotated forward to excavate and mix the ground, they prevent soil from covering the nozzles 60. Such nozzle covers 70 prevent damage to the nozzles 60 and backflow of soil into the rotating shaft 10, maintaining smooth spraying of the slurry 100.

2. Second Embodiment of Excavation and Stirring Apparatus While the excavation and stirring apparatus 1 of the first embodiment described above is configured with three sets of six stirring blades 30 on the rotating shaft 10, the number of stirring blades 30 is not limited to six. As shown in FIG. 4 , the excavation and stirring apparatus 2 of the second embodiment may be configured with four sets of eight stirring blades 30 on the rotating shaft 10. In this case, it is preferable that the anti-rotation blade 40 has a generally Y-shape, with three horizontal sections connected by one vertical section. Such a generally Y-shape anti-rotation blade 40 is fixed to three bosses 41. Each of the three bosses 41 is rotatably attached to three collars 42 attached to the top, middle, and bottom positions of the rotating shaft 10. A blade 50 is fixed to each of the three bosses 41. The middle blade 50 is located 180° opposite the upper and lower blades 50 and is not shown in FIG. 4.

3. Deep Mixing Treatment Method of First Embodiment The deep mixing treatment method of the first embodiment of the present invention will be described with reference to FIG.

As shown in Figure 5, the deep mixing treatment method of the first embodiment uses the excavation and stirring device 1 of the first embodiment described above to construct a column in the ground by mechanically mixing and stirring the slurry 100 and soil while injecting the slurry 100 into the ground. The deep mixing treatment method of the first embodiment constructs one column in the ground by moving the excavation and stirring device 1 back and forth once (one cycle).

The symbols "A" to "F" in Figure 5 indicate the various steps involved in the deep mixing treatment method of the first embodiment. The excavating and stirring device 1 is connected to the rod 80 of a construction machine (not shown) and moves forward or backward through the ground while rotating forward or backward. "Forward rotation" refers to the clockwise direction shown in Figure 3(b), and "reverse rotation" refers to the counterclockwise direction shown in Figure 3(b). For the deep mixing treatment method of the first embodiment, various construction machines can be used, depending on the site and construction conditions, such as a crawler-type three-point support machine, backhoe, small crawler type, crawler crane type, and pole erection vehicle. Note that the excavating and stirring device 1 of the first embodiment is merely an example, and the excavating and stirring device 2 of the second embodiment may also be used.

3.1 Excavation, Mixing and Stirring, and Slurry Discharge First, as shown in A to C in FIG. 5, the excavation and stirring device 1 is rotated forward, and the slurry 100 is sprayed from the nozzle 60 while the device is advanced through the ground, thereby excavating the ground from the position where the head of the column is to be formed to the position where the tip of the column is to be formed, and mixing and stirring the soil and the slurry 100.

3.2 Column Tip Treatment Next, as shown in C and D in Fig. 5, spraying of the slurry 100 from the nozzle 60 is stopped, and the excavating and stirring apparatus 1 is held at the position where the tip of the column will be formed until a predetermined time has elapsed. Next, as shown in E in Fig. 5, after the predetermined time has elapsed, the excavating and stirring apparatus 1 is rotated in the reverse direction and retreated approximately the height of the excavating and stirring apparatus 1. Next, as shown in F in Fig. 5, the excavating and stirring apparatus 1 is rotated forward and advanced to the position where the tip of the column will be formed. Through the above steps, the soil at the tip of the column and the slurry 100 are thoroughly stirred and mixed.

3.3 Raising and stirring the excavation and stirring device Then, as shown in F, G, and H in Figure 5, the excavation and stirring device 1 is reversed to mix and stir the soil and slurry 100, while the excavation and stirring device 1 is retracted from the position where the tip of the column is formed to the position where the head of the column is formed. The above steps complete the deep mixing treatment method of the first embodiment.

4. Deep Mixing Treatment Method of Second Embodiment A deep mixing treatment method of a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG.

As shown in Figures 6 and 7, the deep mixing method of the second embodiment divides the section from where the tip of the column is formed to where the head of the column is formed into an upper section and a lower section, and constructs the lower section of the column first and then the upper section of the column, thereby constructing a single column in the ground.

The deep mixing treatment method of the second embodiment described below is effective when the overall length of the column (the length of the ground improvement) is long and it is difficult to lift the excavation and mixing device 1. In addition, the soil and slurry 100 in the lower section of the column that was constructed first bears the weight of the soil in the upper section that will be constructed later. This prevents the soil and slurry 100 in the lower section of the column that was constructed first from overflowing into the upper section of the column that will be constructed later.

The symbols "A" to "N" in Figures 6 and 7 indicate the various steps included in the deep mixing treatment method of the second embodiment. As with the deep mixing treatment method of the first embodiment described above, the excavation and mixing device 1 is connected to the rod 80 of a construction machine (not shown) and moves forward or backward through the ground while rotating forward or backward. The deep mixing treatment method of the second embodiment can also use a variety of construction machines depending on the site and construction conditions. Note that the excavation and mixing device 1 of the first embodiment is merely an example, and the excavation and mixing device 2 of the second embodiment may also be used.

6A and 6B, the excavating and mixing device 1 is rotated forward and advanced through the ground to excavate the ground from the head of the column to approximately the midpoint where the tip will be formed. In other words, the ground is dry excavated from the head of the column to the midpoint without discharging the slurry 100.

Next, as shown in C and D in Figure 6, the excavating and stirring device 1 is rotated forward and the slurry 100 is sprayed from the nozzle 60 while it is advanced through the ground, thereby excavating the ground from the middle position of the column to the position where the tip is formed, and mixing and stirring the soil and slurry 100.

Next, as shown in D and E in Figure 6, the spraying of slurry from the nozzle 60 is stopped, and the excavating and stirring device 1 is held at the position where the tip of the column will be formed until a predetermined time has elapsed. Next, as shown in F in Figure 6, after the predetermined time has elapsed, the excavating and stirring device 1 is rotated in reverse and retreated approximately the height of the excavating and stirring device 1. Next, as shown in G in Figure 6, the excavating and stirring device 1 is rotated forward and advanced to the position where the tip of the column will be formed. Through these steps, the soil at the tip of the column and the slurry 100 are thoroughly stirred and mixed.

Then, as shown in G and H in Figure 6, the excavation and mixing device 1 is rotated in the reverse direction and retracted to the position where the head of the column will be formed. This completes the construction of the lower section of the column in the deep mixing treatment method of the second embodiment.

4.2 Construction of the upper section of the column Next, as shown in I, J, and K in Figure 7, the excavating and mixing device 1 is rotated forward and the slurry is sprayed from the nozzle while it is advanced through the ground, thereby mixing and mixing the soil and the slurry 100 from the position where the head of the column is formed to the intermediate position.

Next, the spraying of slurry from the nozzle is stopped, and the excavating and stirring device 1 is rotated forward as shown by L in Figure 7, and advanced approximately the height of the excavating and stirring device 1. Then, as shown by M and N in Figure 7, the excavating and stirring device 1 is rotated in the reverse direction and retreated from the middle position of the column to the position where the head is formed. This completes the construction of the upper section of the column. This completes the deep mixing treatment method of the second embodiment, and one column is constructed in the ground.

5. Deep Mixing Treatment Method of Third Embodiment A deep mixing treatment method of a third embodiment of the present invention will be described with reference to FIG.

Checkered steel pipes 90, as shown in Figure 8, may be integrated into the column formed in the ground using the deep mixing methods of the first and second embodiments described above. That is, as shown by H in Figure 5 and N in Figure 7, the slurry 100 and soil are mixed and stirred from the position where the head of the column is formed to the position where the tip of the column is formed, and after the excavation and mixing device 1 is raised from the ground, the checkered steel pipes 90 are inserted into the mixed and stirred slurry 100 and soil. This allows a composite column integrated with the checkered steel pipes 90 to be constructed in the ground.

As shown in Figure 8, the total length of the checkered steel pipe 90 is preferably the total column length L minus the column diameter D. In this case, the length of the checkered steel pipe 90 does not reach the end-improved portion of the column, which has the same height as the column diameter D. Note that the total length of the checkered steel pipe 90 may also be the same as the total column length L. In other words, the total length of the checkered steel pipe 90 is preferably the total column length L minus a value between 0 and D.

According to the third embodiment of the deep mixing method shown in Figure 8, checkered steel pipes 90, which have numerous irregularities on their surfaces, have strong adhesion to the center of the column. By burying and integrating such checkered steel pipes 90 into the column, the column's resistance can be increased, making it possible to effectively utilize the bearing capacity of the ground.

6. Effects and Benefits In the excavation and mixing devices 1 and 2 of the present embodiment and the deep mixing method using them, the nozzle 60 attached to the slurry discharge hole 10b injects slurry into the ground at a pressure higher than normal. This allows the slurry 100 to be dispersed throughout the entire column that will ultimately be constructed. Furthermore, the blade 50 fixed to the boss 41 of the anti-rotation blade 40 can remove lumps of soil adhering to the mixing blade 30, effectively preventing the co-rotation phenomenon. These synergistic effects make it possible to construct high-quality columns with consistent strength.

Furthermore, when constructing a column integrated with checkered steel pipes 90 in the ground, by burying and integrating checkered steel pipes 90, which have strong adhesive strength, into the column, the column's resistance can be increased, and the bearing capacity of the ground can be effectively utilized.

7. Others The excavation and mixing device and the deep mixing treatment method using the same of the present invention are not limited to the configurations and processes of the above-described embodiments. For example, the following modifications are possible.

The outer shape of the nozzle 60 shown in Figures 3(c) and (d) is not limited to a hexagon. The outer shape of the nozzle 60 can be various shapes, such as a triangle, a rectangle, or a circle. Furthermore, the number of nozzles 60 is not limited to two, and they do not have to be interchangeably attached to the rotating shaft 10. For example, the number of nozzles 60 may be one or three or more. When the drilling/mixing blade diameter is small, between 300 and 600 mm, as shown in Figure 9, one nozzle 60 may be welded to one discharge hole 10b of the rotating shaft 10. Furthermore, the outer shape of the nozzle cover 70 shown in Figures 3(a) and (b) is not limited to a semicircle. As shown in Figure 9, the outer shape of the nozzle cover 70 may be, for example, a circle that covers the nozzle 60 from all directions.

In Figure 2, the two second digging claws 22 provided at the tip of the rotating shaft 10 may be, for example, a single fishtail-shaped claw as shown in Figure 9. The digging blade 20 shown in Figure 2 is configured with small first digging claws 21 and large cutting claws 23. This is because the claws on the outer sides of the digging blade 20 are subject to more severe wear, so the outer claws are provided with larger cutting claws 23. However, as shown in Figure 9, all of the claws provided on the digging blade 20 may be first digging claws 21 of the same size. Furthermore, if the diameter of the digging/mixing blade is small, between 300 and 600 mm, the lifting claw 31 shown in Figure 2 may be omitted.

In the second embodiment of the deep mixing treatment method, the slurry discharge start position at B in Figure 6 is set to approximately the midpoint between the head of the column and the position where the tip is formed. However, the slurry discharge start position is not limited to the midpoint, and can be set to any position between the position where the head of the column is formed and the position where the tip of the column is formed.

1, 2 Excavation and mixing device 10 Rotation shaft 10a Conduction passage 10b Slurry discharge hole 11 Joint 20 Excavation blade 21 First excavation claw 22 Second excavation claw 23 Cutting claw 30 Mixing blade 31 Lifting claw 40 Co-rotation prevention blade (free blade)
41 boss 42 collar 50 blade 60 nozzle 61 head 62 male thread 63 flow path 63a inlet 63b outlet 70 nozzle cover 80 rod 90 checkered steel pipe 100 slurry

Claims (10)

An excavation and mixing device for constructing a column in the ground by mechanically mixing and mixing a slurry obtained by mixing a cement-based solidification material with water into the ground,
a cylindrical rotating shaft having a conduit therein for supplying the slurry into the ground and having a slurry discharge hole at its tip end that communicates with the conduit;
an excavation wing fixed to a tip end of the rotary shaft, extending horizontally from the rotary shaft, and having an excavation claw attached thereto for excavating the ground;
A stirring blade fixed to a portion other than the tip of the rotating shaft for stirring the ground;
a co-rotation prevention blade that is fixed to a boss that is rotatably attached to the outside of a portion of the rotary shaft other than the tip end portion, and that prevents the rotation of the rotary shaft from being transmitted by the boss;
a nozzle having a male screw portion that is screwed into a slurry discharge hole located at the tip of the rotary shaft, and a hexagonal head portion that is continuous with the male screw portion, and a tapered flow path that extends horizontally from an inlet and tapers toward an outlet, for accelerating the flow of the slurry and injecting it from the head into the rotational orbit of the drilling blade ;
A drilling and stirring device comprising: The drilling and stirring device according to claim 1 , wherein two or more of the slurry discharge holes are formed in the tip of the rotary shaft, and the nozzle is attached to each of the two or more slurry discharge holes. 3. The excavating and stirring device according to claim 1, wherein the nozzle has an outlet diameter of 5 mm to 25 mm, and the nozzle is detachably attached to the slurry discharge hole. A nozzle cover for preventing the soil of the ground from covering the nozzle when the rotating shaft is rotated in one direction is provided at the tip of the rotating shaft. The excavating and stirring apparatus according to any one of claims 1 to 3. The excavation and stirring device according to any one of claims 1 to 4, wherein three or four sets of two stirring blades are provided, and the stirring blades of each set are fixed at symmetrical positions in different parts other than the tip of the rotating shaft. The excavating and stirring device according to any one of claims 1 to 5, wherein a blade extending vertically is fixed to the boss to which the co-rotation prevention blade is fixed. The anti-rotation blade is approximately U-shaped or approximately Y-shaped, and has two or three bosses for fixing two or three ends of the anti-rotation blade, respectively, and the blade is fixed to at least one of the bosses. Excavation and stirring device as described in claim 6. A deep mixing method for constructing a column in the ground by mechanically mixing and stirring the slurry and soil while injecting a slurry obtained by mixing a cement-based solidification material with water into the ground using the excavation blade stirring device according to any one of claims 1 to 7.
A process of rotating the excavation and stirring device in one direction and moving the device through the ground while spraying the slurry from the nozzle, thereby excavating the ground from the position where the head of the column is formed to the position where the tip of the column is formed, and mixing and stirring the slurry and soil;
A step of stopping the spraying of the slurry from the nozzle and holding the excavating and stirring device at a position where the tip of the column is formed until a predetermined time has elapsed;
After the predetermined time has elapsed, the excavating and stirring device is rotated in the reverse direction while being retreated approximately by the height of the excavating and stirring device;
A step of rotating the excavation and stirring device in one direction and advancing it to a position where the tip of the column is formed;
A step of retracting the excavation and stirring device to a position where the head of the column is formed while rotating it in a reverse direction;
A deep mixing treatment method comprising: A deep mixing method for constructing a column in the ground by mechanically mixing and stirring the slurry and soil while injecting a slurry obtained by mixing a cement-based solidification material with water into the ground using the excavation blade stirring device according to any one of claims 1 to 7.
A step of excavating the ground to an arbitrary position between a position where the head of the column is formed and a position where the tip of the column is formed by rotating the excavation and stirring device in one direction and moving it through the ground;
A process of excavating the ground from the arbitrary position to a position where the tip of the column is formed by rotating the excavation and stirring device in one direction and spraying the slurry from the nozzle while moving through the ground, and mixing and stirring the slurry and soil;
A step of stopping the spraying of the slurry from the nozzle and holding the excavating and stirring device at a position where the tip of the column is formed until a predetermined time has elapsed;
After the predetermined time has elapsed, the excavating and stirring device is rotated in the reverse direction while being retreated approximately by the height of the excavating and stirring device;
A step of rotating the excavation and stirring device in one direction and advancing it to a position where the tip of the column is formed;
A step of retracting the excavation and stirring device to a position where the head of the column is formed while rotating it in a reverse direction;
A process of rotating the excavation and stirring device in one direction and moving the excavation and stirring device through the ground while spraying the slurry from the nozzle, thereby mixing and stirring the slurry and soil from the position where the head of the column is formed to the arbitrary position;
A step of stopping the spraying of the slurry from the nozzle and retracting the drilling and stirring device from the arbitrary position to a position where the head of the column is formed while rotating the drilling and stirring device in a reverse direction;
A deep mixing treatment method comprising: 10. The deep mixing treatment method according to claim 8 or 9, wherein the slurry and soil are mixed and stirred from the position where the head of the column is to be formed to the position where the tip of the column is to be formed, and after the excavation and stirring device is pulled up from the ground, a checkered steel pipe is inserted into the mixed and stirred slurry and soil, thereby constructing the column integrated with the checkered steel pipe in the ground.