Excavation and mixing equipment and deep mixing treatment method

Abstract

To provide an excavation and agitation device which can diffuse a slurry to the whole of a column that is finally constructed and can effectively prevent a corotation phenomenon, and thereby can construct a column of high quality without variation in strength.SOLUTION: An excavation and agitation device includes: a cylindrical rotation shaft 10 where a slurry discharge hole is formed at the tip; an excavation blade 20 which is fixed to the tip of the rotation shaft 10 and is mounted with an excavation claw for excavating the ground; an agitation blade 30 which is fixed to a part other than the tip of the rotation shaft 10, and agitates the ground; a corotation prevention blade 40 which is fixed to a boss 41 rotatably mounted on the outside of a part other than the tip of the rotation shaft 10 and prevents rotation of the rotation shaft 10 from being transmitted by the boss 41; and a nozzle 60 which is mounted on the slurry discharge hole of the rotation shaft 10, has a flow channel of the slurry having a smaller diameter toward an outlet from an inlet provided therein, accelerates a flow of the slurry and jets the slurry into the ground.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] 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 and soil while injecting a slurry (cement milk) made by mixing a cement-based solidification material with water into the ground. [Background technology]

[0002] 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 constructing columns (columnar improvement bodies) in the ground. The columns reinforce the ground and support the structure. In this specification, the term "cement-based solidification material" refers to a solidification material containing cement as its main component for the purpose of solidifying soil, and is sometimes referred to as a "solidification material." In this specification, the term "slurry" refers to a liquid made by mixing a cement-based solidification material with water, and is sometimes referred to as "cement milk."

[0003] 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, on which an excavating blade, an agitating blade, and a co-rotation prevention blade are provided. 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 excavating blade excavates the ground, and the excavated soil and slurry are mixed and stirred by the agitating 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 stopped, the co-rotation prevention blade prevents the soil and slurry being mixed and stirred from rotating together. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-214911 [Patent Document 2] Japanese Patent Application Publication No. 2017-048616 [Patent Document 3] Utility Model Registration No. 3215453 Summary of the Invention [Problem to be solved by the invention]

[0005] In 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 is not dispersed throughout the entire column that is ultimately constructed, and unsolidified soil lumps are mixed into the column, resulting in variations in the strength of the column.

[0006] Furthermore, conventional excavation and mixing devices are equipped with anti-rotation blades, but they are unable to remove lumps of soil that have adhered to the blades. As the excavation and mixing of the ground progresses using the excavation and mixing device, the soil adheres to the blades over time, forming lumps, causing the blades and the soil lumps to rotate together. This co-rotation phenomenon results in insufficient mixing of the slurry and soil by the blades, resulting in insufficient strength for the final column.

[0007] Furthermore, with conventional excavation and mixing devices, the problem of the slurry not being sufficiently spread and the problem of co-rotation sometimes occurred at the same time, making it difficult to always build columns of the specified quality.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an excavation and mixing device and a deep mixing treatment method that can spread slurry throughout the entire column that is ultimately constructed and effectively prevent the co-rotation phenomenon, thereby making it possible to construct high-quality columns with no variation in strength. [Means for solving the problem]

[0009] (1) In order to achieve the above object, the excavating and stirring device of the present invention is an excavating and stirring device for constructing a column in the ground by mechanically mixing and stirring a slurry, which is a mixture of cement-based solidification material and water, while injecting the slurry into the ground, and the excavating and stirring device comprises: a cylindrical rotating shaft having an internal conduit for supplying the slurry into the ground and having 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 thereto for excavating the ground; a stirring blade fixed to a part 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 part of the rotating shaft other than the tip, and the boss does not transmit the rotation of the rotating shaft; 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 injecting it into the ground.

[0010] (2) Preferably, in the drilling and stirring device of (1) above, two or more of the slurry discharge holes are formed at the tip of the rotary shaft, and the nozzle is attached to each of the two or more slurry discharge holes.

[0011] (3) Preferably, in the drilling and stirring device of (1) or (2) above, the nozzle has an outlet diameter of 5 mm to 25 mm, and the nozzle is detachably attached to the slurry discharge hole.

[0012] (4) Preferably, in any of the excavating and mixing devices (1) to (3) above, a nozzle cover is provided at the tip of the rotating shaft to prevent soil from the ground from covering the nozzle when the rotating shaft is rotated in one direction.

[0013] (5) Preferably, in any of the drilling and stirring devices (1) to (4) above, 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.

[0014] (6) Preferably, in the excavating and stirring device of any one of (1) to (5) above, a blade extending vertically is fixed to the boss to which the anti-co-rotation blade is fixed.

[0015] (7) Preferably, in the excavation and stirring device of (6) above, the anti-rotation blade is approximately U-shaped or approximately Y-shaped, and is provided with 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.

[0016] (8) In order to achieve the above object, the deep mixing method of the present invention is a deep mixing method that uses any one 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, which is a mixture of a cement-based solidification material and water, into the ground, and the slurry and soil are injected into the ground by rotating the excavation and stirring device in one direction and spraying the slurry from the nozzle while moving the excavation and stirring device through the ground, thereby excavating the ground from a position where the head of the column is to be formed to a position where the tip of the column is to be formed, and The method 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 at a position where the tip of the column is to be formed until a predetermined time has elapsed, and after the predetermined time has elapsed, rotating the excavating and stirring device in the reverse direction while retreating it approximately the height of the excavating and stirring device, rotating the excavating and stirring device in one direction while advancing it to a position where the tip of the column is to be formed, and rotating the excavating and stirring device in the reverse direction while retreating it to a position where the head of the column is to be formed.

[0017] (9) In order to achieve the above object, the deep mixing method of the present invention is a deep mixing method for constructing a column in the ground by using an excavation and stirring device of any one of (1) to (7) above to mechanically mix and stir the slurry, which is a mixture of a cement-based solidification material and water, into the ground, while injecting the slurry into the ground, and mechanically mixing and stirring the slurry and soil, the method comprising the steps of: rotating the excavation and stirring device in one direction while moving it through the ground to excavate the ground up to an arbitrary position between a position where the head of the column is to be formed and a position where the tip of the column is to be formed; excavating the ground from the arbitrary position to a position where the tip of the column is to be formed and mixing and stirring the slurry and soil by moving it through the ground while rotating the excavation and stirring device in one direction and injecting the slurry from the nozzle; and stopping the injection of the slurry from the nozzle and injecting the slurry for a predetermined time. the excavation stirring apparatus is rotated in one direction while advancing to the position where the tip of the column is to be formed; the excavation stirring apparatus is rotated in the reverse direction while advancing to the position where the head of the column is to be formed; the excavation stirring apparatus is rotated in the reverse direction while advancing to the position where the head of the column is to be formed; the excavation 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 excavation stirring apparatus is rotated in the reverse direction 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.

[0018] (10) Preferably, in the deep mixing method of (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. [Effects of the Invention]

[0019] In the excavation and mixing equipment and deep mixing method of the present invention, the slurry is injected into the ground at a higher pressure than usual 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 fixed to the boss of the anti-rotation blade can remove lumps of soil adhering to the mixing blade, effectively preventing the co-rotation phenomenon. These synergistic effects make it possible to construct high-quality columns with consistent strength. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a front view showing an excavating and stirring apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a right side view showing the excavating and stirring apparatus according to the first embodiment. [Figure 3] Figure 3(a) is an enlarged view of the tip of the excavating and stirring device of Figure 1. Figure 3(b) is a cross-sectional view taken along line AA of Figure 3(a). Figure 3(c) is a front view showing a nozzle provided at the tip of the excavating and stirring device. Figure 3(d) is a right side view showing the nozzle. Figure 3(e) is a cross-sectional view showing the nozzle. [Figure 4] FIG. 4 is a front view showing an excavating and stirring apparatus according to a second embodiment of the present invention. [Figure 5] 1 is a schematic diagram showing a deep mixing treatment method according to a first embodiment of the present invention. FIG. [Figure 6] 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. [Figure 7]FIG. 10 is a schematic diagram showing the second half of the deep mixing treatment method according to the second embodiment. [Figure 8] FIG. 10 is a schematic diagram showing a deep mixing treatment method according to a third embodiment of the present invention. [Figure 9] 10 is a schematic diagram showing the main parts of a modified example of the excavating and stirring device of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] 1. First embodiment of the excavation and stirring device A drilling and stirring apparatus according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

[0022] As shown in FIGS. 1 and 2, the excavating and stirring device 1 is mainly composed of a rotary shaft 10, an excavating blade 20, an stirring blade 30, a co-rotation prevention blade 40, and a blade 50.

[0023] 1.1 Rotation axis As shown in Figures 1, 2, and 3(b), the rotating shaft 10 is a cylindrical member having a conduit 10a therein. A slurry 100 (see Figures 5 to 7) made by mixing a cement-based solidification material with 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.

[0024] Two slurry discharge holes 10b communicating 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 an internal thread formed on their inner circumferential surfaces. For example, the inner diameter of the slurry discharge hole 10b is 36 mm. Nozzles 60, which will be described later, are replaceably attached to the two slurry discharge holes 10b with screws.

[0025] Here, the excavating and stirring apparatus 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 discharge 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.

[0026] 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.

[0027] 1.2 Drilling blade As shown in FIG. 2, the excavating and stirring device 1 includes two excavating blades 20. The two excavating blades 20 are fixed at positions symmetrical to each other at the tip of the rotating shaft 10. Two first excavating claws 21 are attached to the inner side in the longitudinal direction of each excavating blade 20. Furthermore, one cutting claw 23 is attached to the outer side in the longitudinal direction of each excavating blade 20. Furthermore, two second excavating claws 22 are fixed vertically to the tip surface of the rotating shaft 10. For example, the total length of one excavating blade 20 is 330 mm. The total diameter of the two excavating blades 20 and the diameter of the rotating shaft 10 forms an excavated hole in the ground with a diameter of approximately 800 mm.

[0028] 1.3 Mixing blade As shown in Figures 2 and 3, the excavating and stirring device 1 has three pairs of mixing blades 30, for a total of six mixing blades 30. All six mixing blades 30 are fixed to the rotating shaft 10 closer to the rear end than the drilling blade 20. The pairs of mixing blades 30 are arranged symmetrically on the rotating shaft 10. Of the three pairs of mixing blades 30 arranged at the top, middle, and bottom of the rotating shaft 10, the middle pair of mixing blades 30 is arranged 90° shifted from the two pairs of mixing blades 30 above and below. Each pair of mixing blades 30 arranged on the rotating shaft 10 is equipped with a lifting claw 31. The lifting claw 31 is arranged on the outer side of the mixing blade 30 in the longitudinal direction. For example, the total length of one mixing blade 30 is 330 mm, the same as the drilling blade 20.

[0029] 1.4 Anti-corotation blade As shown in FIG. 1 , the excavating and stirring device 1 includes a pair of anti-rotation vanes (free vanes) 40. Each anti-rotation vane 40 has a roughly U-shape with two horizontal sections connected by one vertical section. The ends of the two horizontal sections of the anti-rotation vane 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 in contact with 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 anti-rotation vanes 40. By constructing the collars 42 from wear-resistant steel plate, wear due to contact with the anti-rotation vanes 40 is reduced.

[0030] Each anti-rotation impeller 40 is composed of two horizontal sections, one above the other, and one vertical section that is continuous with these two horizontal sections. For example, the horizontal projection length of one anti-rotation impeller 40 from the rotation shaft 10 to the vertical section is 430 mm, which exceeds the overall length of the excavating impeller 20 and the mixing impeller 30. The vertical section of the anti-rotation impeller 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 impeller 40 stationary. The soil and slurry 100 mixed and mixed by the mixing impeller 30 come into contact with the horizontal section of the stationary anti-rotation impeller 40, preventing the soil and slurry 100 from rotating together.

[0031] 1.5 Earth removal plate As shown in Fig. 2, the excavating and mixing device 1 is equipped with two blades 50. The two blades 50 are fixed to 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 the soil lumps adhering to the mixing blades 30 to remove them.

[0032] 1.6 Nozzle As shown in Figures 3(a) and 3(b), two nozzles 60 are attached interchangeably to 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 present invention is characterized by spraying the slurry 100 at a higher pressure than usual using the nozzle 60 attached to the slurry discharge port 10b. 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 makes it possible to construct high-quality columns with minimal variation in strength.

[0033] 3(c) to 3(e), the nozzle 60 in this embodiment is composed of a hexagonal head 61, a male thread portion 62 for threadably engaging with the female thread portion of the slurry discharge port 10b, and a tapered flow path 63 for accelerating the flow of the slurry 100. The outlet 63b of the nozzle 60 has a smaller diameter than the inlet 63a.

[0034] The diameter of the outlet 63b of the nozzle 60 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 outlet 63b of the nozzle 60, the number of nozzles 60, and the diameter of the drilling and stirring blades when discharging 50 to 500 liters of slurry 100 per minute are shown in Table 1 below. The drilling and stirring blade diameter is the sum of the total length of one set of drilling and stirring blades 20 or stirring blades 30 and the diameter of the rotating shaft 10. For example, the drilling and stirring blade diameter in this embodiment is 330 mm + 330 mm + 139 mm ≈ 800 mm.

[0035] [Table 1]

[0036] 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, the nozzle covers 70 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, thereby maintaining smooth spraying of the slurry 100.

[0037] 2. Second embodiment of excavation and stirring device While the excavating 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 excavating 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, the anti-rotation blade 40 is preferably configured in 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.

[0038] 3. First embodiment of deep mixing treatment method The deep mixing method according to the first embodiment of the present invention will be described with reference to FIG.

[0039] As shown in Fig. 5, the deep mixing treatment method of the first embodiment uses the excavating and stirring apparatus 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 excavating and stirring apparatus 1 back and forth once (one cycle).

[0040] The symbols "A" to "F" in Figure 5 indicate multiple steps included in the deep mixing treatment method of the first embodiment. The excavation and mixing device 1 is connected to a 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 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.

[0041] 3.1 Excavation, mixing, and slurry discharge First, as shown in A to C in Figure 5, 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 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.

[0042] 3.2 Column end 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.

[0043] 3.3 Pulling up and mixing the excavation and mixing equipment 5F, G, and H, the excavation and stirring apparatus 1 is reversed to mix and stir the soil and slurry 100, while the excavation and stirring apparatus 1 is retreated from the position where the tip of the column is to be formed to the position where the head of the column is to be formed. The above steps complete the deep mixing treatment method of the first embodiment.

[0044] 4. Second embodiment of deep mixing treatment method A deep mixing method according to a second embodiment of the present invention will be described with reference to FIGS.

[0045] As shown in Figures 6 and 7, the deep mixing treatment method of the second embodiment divides the section from the position where the tip of the column is formed to the position 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 later, thereby constructing a single column in the ground.

[0046] The deep mixing treatment method of the second embodiment described below is effective when the total 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.

[0047] The symbols "A" to "N" in Figures 6 and 7 indicate multiple 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 various 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.

[0048] 4.1 Construction of the lower section of the column First, as shown in A and B in Fig. 6, the excavating and stirring device 1 is rotated forward and advanced through the ground to excavate the ground from the head of the column to approximately the midpoint between 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.

[0049] 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 the slurry 100.

[0050] Next, as shown in D and E in FIG. 6, spraying of the slurry from the nozzle 60 is stopped, and the excavating and stirring apparatus 1 is held at the position where the tip of the column is to be formed until a predetermined time has elapsed. Next, as shown in F in FIG. 6, 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 G in FIG. 6, the excavating and stirring apparatus 1 is rotated forward and advanced to the position where the tip of the column is to be formed. Through the above steps, the soil at the tip of the column and the slurry 100 are sufficiently stirred and mixed.

[0051] Thereafter, as shown in G and H in Figure 6, the excavation and mixing device 1 is rotated in the reverse direction and retreated to the position where the head of the column is formed. Through the above steps, the construction of the lower section of the column in the deep mixing treatment method of the second embodiment is completed.

[0052] 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 moved through the ground, mixing and mixing the soil and slurry 100 from the position where the head of the column is formed to the intermediate position.

[0053] Next, the injection of slurry from the nozzle is stopped, and the excavating and stirring device 1 is rotated forward as shown by L in FIG. 7, and advanced approximately the height of the excavating and stirring device 1. Then, as shown by M and N in FIG. 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. The above steps complete 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.

[0054] 5. Third embodiment of deep mixing treatment method A deep mixing treatment method according to a third embodiment of the present invention will be described with reference to FIG.

[0055] A checkered steel pipe 90 shown in Fig. 8 may be integrated with a column formed in the ground by the deep mixing treatment method of the first and second embodiments described above. That is, as shown by H in Fig. 5 and N in Fig. 7, the slurry 100 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 apparatus 1 is pulled out of the ground, the checkered steel pipe 90 is inserted into the mixed and stirred slurry 100 and soil. In this way, a composite column integrated with the checkered steel pipe 90 can be constructed in the ground.

[0056] As shown in FIG. 8, the total length of the checkered steel pipe 90 is preferably the total length of the column 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 be the same as the total length of the column L. In other words, the total length of the checkered steel pipe 90 is preferably the total length of the column L minus a value between 0 and D.

[0057] According to the deep mixing method of the third embodiment shown in Figure 8, the checkered steel pipe 90, which has many irregularities on its surface, has a strong adhesive force with the center of the column. By embedding and integrating such checkered steel pipe 90 into the column, the resistance of the column can be increased, and the bearing capacity of the ground can be effectively utilized.

[0058] 6. Effects In the above-described excavation and mixing apparatuses 1 and 2 of this embodiment and the deep mixing method using them, the nozzle 60 attached to the slurry discharge hole 10b injects slurry 100 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 impeller 40 can remove lumps of soil adhering to the impeller 30, effectively preventing the co-rotation phenomenon. These synergistic effects make it possible to construct high-quality columns with consistent strength.

[0059] Furthermore, when constructing a column integrated with checkered steel pipes 90 in the ground, by burying and integrating checkered steel pipes 90, which have a high adhesive strength, into the column, the resistance of the column can be increased, and the bearing capacity of the ground can be effectively utilized.

[0060] 7.Other The excavation and mixing apparatus 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.

[0061] The outer shape of the nozzle 60 shown in FIGS. 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. The number of nozzles 60 is not limited to two, and they do not have to be replaceably 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, 300 to 600 mm, as shown in FIG. 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 FIGS. 3(a) and (b) is not limited to a semicircle. As shown in FIG. 9, the outer shape of the nozzle cover 70 may be, for example, a circle that covers the nozzle 60 from all directions.

[0062] In FIG. 2, the two second digging claws 22 provided at the tip of the rotating shaft 10 may be, for example, a single fishtail type as shown in FIG. 9. The digging blade 20 shown in FIG. 2 is configured with small first digging claws 21 and large cutting claws 23. This is because the outer claws of the digging blade 20 are subject to more severe wear, so the outer claws are made larger cutting claws 23. However, as shown in FIG. 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 a small diameter of 300 to 600 mm, the lifting claw 31 shown in FIG. 2 may be omitted.

[0063] In the deep mixing treatment method of the second embodiment, the position where the slurry discharge starts, indicated by B in Fig. 6, is approximately halfway between the head of the column and the position where the tip of the column is formed. However, the position where the slurry discharge starts is not limited to the halfway position, and can be any position between the position where the head of the column is formed and the position where the tip of the column is formed. [Explanation of symbols]

[0064] 1, 2 Excavation and mixing equipment 10 Rotation axis 10a Conduit path 10b Slurry discharge hole 11 Joint 20 Drilling Wing 21 First Excavation Claw 22 Second digging claw 23 Cutting jaw 30 stirring blade 31 Lifting claw 40 Anti-corotation wing (free wing) 41 Boss 42 Color 50 Earth removal plate 60 nozzles 61 Head 62 Male thread 63 Flow path 63a entrance 63b Exit 70 Nozzle cover 80 rods 90 Striped steel pipe 100 Slurry

Claims

1. 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:

2. Two or more of the slurry discharge holes are formed at the tip of the rotary shaft, and the nozzle is attached to each of the two or more slurry discharge holes. The drilling and stirring device according to claim 1.

3. The nozzle has an outlet diameter of 5 mm to 25 mm, and the nozzle is detachably attached to the slurry discharge hole. The drilling and stirring device according to claim 1 or 2.

4. A nozzle cover is provided at the tip of the rotary shaft to prevent the nozzle from being covered with soil from the ground when the rotary shaft is rotated in one direction. The drilling and stirring device according to any one of claims 1 to 3.

5. Three or four pairs of the stirring blades are provided, and the stirring blades of each pair are fixed at symmetrical positions in different parts of the rotating shaft other than the tip end. The drilling and stirring device according to any one of claims 1 to 4.

6. A blade extending vertically is fixed to the boss to which the anti-corotation blade is fixed. The excavating and stirring device according to any one of claims 1 to 5.

7. The anti-rotation blade is generally U-shaped or generally Y-shaped, and includes 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. The drilling and stirring device according to claim 6.

8. 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:

9. 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 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. The deep mixing treatment method according to claim 8 or 9.

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