JP4070733B2 - Mechanical stirring ground improvement device - Google Patents

Description

  The present invention relates to a mechanically agitated ground improvement device for agitating and mixing a solidified material such as cement slurry with excavated earth and sand in situ to create a ground improvement body in the ground.

  Conventionally, a deep mixed treatment method has been frequently used as a ground improvement method such as revetment, breakwater, underline dike, road and land preparation. Basically, as shown in FIG. 6, this construction method penetrates into the ground while rotating the stirring rod 50 composed of the stirrer 52 having the stirring blades 51, 51 at the tip part around the axis. A ground improvement body is created in the ground by the chemical hardening action of the solidified material such as cement slurry discharged from the part and stirring in and in situ with the soil.

  In recent years, many improvements have been proposed for the agitating blade structure of the deep-mixing processor. For example, as one of those improved techniques, there has been proposed one in which two types of stirring blades that are inverted are provided inside and outside in order to prevent excavated sediment and solidified material from rotating together with the stirring blades.

  For example, in the following Patent Document 1, the rotating shaft is configured as a double shaft of an outer shaft and a middle shaft that rotate in opposite directions, and a semi-arc-shaped large and small stirring blade body is connected to the lower end portion of the inner and outer shafts, respectively. In addition, there has been proposed a stirring blade structure of a ground improvement device in which the large and small stirring blade bodies are configured such that the small stirring blade body is positioned inside the large stirring blade body and rotates in the opposite direction inside and outside each other.

  In the following Patent Document 2, a hollow shaft is formed by integrally forming a screw body on the outer surface of a drum casing of an underground mixer provided at the lower end of the hollow shaft, forming a window between the pitches of the screw body, and concentrically passing therethrough. There has been proposed a ground improvement device in which one forward stirring blade is provided between the pipe and the drum casing, and another reverse stirring blade is provided from the inner pipe.

Furthermore, in the following Patent Document 3, an upper stirring blade portion is formed by an arc-shaped outer blade connected to the outer shaft and an inner blade positioned in the arc-shaped outer blade and connected to the middle shaft. Below the wing part, the lower agitation is performed by the arc-shaped outer wing connected to the central shaft and the middle wing located at the arc-shaped outer wing position and connected to the outer wing of the upper agitation wing part via the agitation wing body mounting part. There has been proposed a ground improvement device in which a wing portion is formed, and a drilling blade portion is continuously provided at the lower end of the middle shaft below the wing portion to rotate the outer shaft and the middle shaft in opposite directions.
JP-A-3-63312 JP-A-6-341138 JP-A-8-109628

  However, as shown in the above-mentioned Patent Document 1, the small stirring blade body (inner blade) is positioned inside the large stirring blade body (outer blade) and is configured to rotate in the opposite direction on the inner and outer sides. Since it is possible to completely prevent co-rotation where the stirring soil and the rotating shaft rotate together, it will greatly contribute to the creation of a high-quality ground improvement body, but the ground improvement body eliminates hole bending. When it is necessary to create the structure with high accuracy along the vertical axis, the vertical accuracy may not be sufficiently ensured due to factors such as a difference in rotational resistance between the outer wing and the inner wing.

  Moreover, in the case of the ground improvement apparatus shown by the said patent document 2, since a drum casing is provided in the lower end of a hollow shaft, since this becomes a penetration guide at the time of ground penetration, it becomes easy to ensure comparatively vertical accuracy. . However, there has been a problem that the peripheral friction resistance between the drum casing and the ground is large, and penetration / extraction may be difficult. In this document, in order to reduce the peripheral frictional resistance, a screw is formed on the outer surface of the drum casing so as to allow penetration by a so-called screw action, but the peripheral frictional resistance itself has not been reduced yet.

  Further, in the ground improvement device disclosed in Patent Document 3, the outer blade and the middle blade rotate in the forward and reverse directions in the stirring blade portion formed in two upper and lower stages, and the upper stirring blade portion and the lower stirring blade portion. By reversing the rotation direction of the outer wing and the middle wing, co-rotation is prevented, and the excavated earth and solidified material are sheared and agitated, but the structure is complicated and the production cost There was a problem such as swell.

  Therefore, the main problem of the present invention is to prevent co-rotation and effectively agitate the excavated sediment and the solidified material, improve the vertical accuracy of the agitating rod, and reduce the penetration resistance and pulling resistance of the agitating rod. It is in.

In order to solve the above-mentioned problem, as the present invention according to claim 1, the solidification discharged in the process of penetrating and / or withdrawing into the ground while rotating a stirring rod provided with a stirring blade at the tip around the axis. In a mechanical stirring type ground improvement device that stirs and mixes wood and in-situ soil
The stirring rod has a double tube structure composed of an outer shaft and a middle shaft, and the stirring blade is provided on the outer shaft and rotates in the forward direction together with the outer shaft, and the inner side of the outer stirring blade. An inner stirring blade provided on the middle shaft and rotating in the opposite direction together with the middle shaft,
Said outer stirring blade, a radiation frame wings extending from the outer shaft to the outside, and extending downwardly from the radiation frame wings, the frame wings peripheral comprising a hanging frame wings bent inwardly at the bottom side The excavation guide ring is supported at the tip of the drooping frame wing, and the outer diameter of the excavation guide ring is smaller than the outer diameter of the drooping frame wing of the outer stirring vane. In addition, a drilling bit is provided on the lower surface of the inner bent portion of the drooping frame wing between the outer diameter of the drooping frame wing and the outer diameter of the excavation guide ring, and inside the excavation guide ring, There is provided a mechanically agitated ground improvement device provided with a drilling blade having an outer diameter close to or substantially in sliding contact with an inner peripheral surface of the excavation guide ring with respect to a central shaft .

  According to a second aspect of the present invention, there is provided the mechanical stirring type ground improvement device according to the first aspect, wherein the radial frame blade portion of the outer stirring blade has a flat cross-sectional shape and is inclined with respect to the rotation direction. Is done.

As a third aspect of the present invention, the drooping frame blade portion of the outer stirring blade is provided with a horizontal blade directed toward the stirring rod, and the inner stirring blade has a vertical position different from that of the horizontal blade of the outer stirring blade. The mechanically agitated ground improvement device according to claim 1 or 2, wherein the horizontal blades are flatly arranged in cross section and inclined with respect to the rotation direction.

As a fourth aspect of the present invention according to any one of claims 1 to 3, wherein a screw blade is provided on the outer peripheral surface of the stirring rod on the upper side of the stirring blade to reduce the pulling resistance when the stirring rod is pulled out. The mechanical stirring type ground improvement apparatus of 1 item | term is provided.

As a fifth aspect of the present invention, the discharge port for the solidified material can be arbitrarily switched between a first discharge port provided at the tip of the stirring rod and an upper position and a lower position of the stirring blade. The mechanical stirring type ground improvement apparatus of any one of Claims 1-4 provided with a 2nd discharge outlet is provided.

  As described above in detail, according to the present invention, it is possible to prevent co-rotation and effectively stir the excavated sediment and the solidified material. In addition, the vertical accuracy of the stirring rod can be improved, and the penetration resistance and the drawing resistance of the stirring rod can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a front view of a mechanical stirring type ground improvement device 1 according to the present invention, FIG. 2 is a side view thereof, FIG. 3 is a plan view of the stirring blade portion, and FIG. 4 is a bottom view thereof.

  A mechanical stirring type ground improvement device 1 shown in FIG. 1 is an example of a two-shaft type ground improvement device. While rotating a stirring rod R having a stirring blade 2 at a tip end around an axis, In the drawing process, the solidified material to be discharged and the in-situ soil are mixed with stirring. The agitation rods R and R are connected to each other by an anti-blend connecting member 21 via a bearing member 20.

The stirring rod R has a double-pipe structure composed of an outer shaft R _O and a middle shaft R _i, and each is rotated in the forward and reverse directions.

The stirring blades 2 are provided on the outer shaft R _O, and outer agitation blades 3 to rotate in the forward direction together with the outer shaft R _O, provided in the inside of the outer stirring impeller 3 to the middle axle R _i, wherein and a inner stirring blade 4 that rotates in the reverse direction together with the inner shaft R _i. A small diameter auger 6 is provided at the tip of the stirring rod R.

The outer agitating blade 3 has a frame blade composed of a radial frame blade portion 3A extending outward from the outer shaft R _O and a hanging frame blade portion 3B extending downward from the radial frame blade portion 3A in the circumferential direction. A plurality, three in the illustrated example, are provided, and the excavation guide ring 5 is supported at the lower end of the drooping frame wing 3B. The hanging frame blade portion 3B is provided with two horizontal blades 7 and 7 directed toward the stirring rod R.

The radial frame blade portion 3A of the outer stirring blade 3 has a flat cross-sectional shape and is inclined with respect to the rotation direction. In this case, the inclination angle is 5 to 15 °, preferably 8 to 12 °. Therefore, when the outer shaft R _O is rotated in a direction in which the inclination direction of the radiating frame wing part 3A is an oblique angle with respect to the rotation direction, the downward component force according to the inclination angle of the radiating frame wing part 3A is obtained. Therefore, it becomes easy to penetrate the stirring rod R into the ground. Further, when the outer shaft R _O is reversely rotated at the time of extraction, the inclination direction of the radiating frame wing part 3A becomes an elevation angle with respect to the rotation direction, and an upward component force corresponding to the inclination angle of the radiating frame wing part 3A is generated. Therefore, it becomes easy to pull out the stirring rod R. The horizontal blades 7 and 7 provided on the drooping frame blade portion 3B also have a flat cross-sectional shape and are inclined with respect to the rotation direction. As described above, the stirring rod R can be easily penetrated during penetration, and when it is pulled out. It is desirable that the stirring rod R be easily pulled out.

  The excavation guide ring 5 is a ring-shaped member provided coaxially with the stirring rod R, and excavation bits 5a, 5a... Are provided on the lower surface side at appropriate intervals along the circumferential direction. This excavation guide ring 5 is provided in order to prevent the stirring rod R from bending in the intrusion process and improve the vertical accuracy. For example, when the stirring rod R penetrates, First, the auger 6 at the tip is penetrated, and the excavation guide ring 5 is penetrated around the auger 6. In this state, the mixing and mixing of the excavated sediment and the solidified material is performed by the stirring blade 2 at a position directly above the excavation guide ring 5, depending on factors such as a difference in rotational resistance between the outer stirring blade 3 and the inner stirring blade 4. Even if an unbalanced force is applied in the rod orthogonal direction, the excavation guide ring 5 penetrates into the unexcavated ground, so that the bending of the hole is suppressed.

Also, the drill guide ring 5, in order to reduce the skin friction resistance during penetration and during withdrawal, the outer diameter R _n is smaller than the outer diameter R _m of hanging frame wings 3B of the outer agitation blades 3 It is desirable that In this case, the outer diameter R _m of the hanging frame wings 3B, the drill guide ring 5 having an outer diameter of the drill bit 3a in the lower surface portion of the hanging frame wings 3B between R _n, 3a ... provided It is desirable to do so.

On the other hand, the inner stirring blades 4 are horizontal blades 8, 8... Arranged in different vertical positions from the horizontal blades 7, 7 of the outer stirring blade 3, and are provided in a three-stage arrangement in the illustrated example. . The horizontal blades 8 and 8 also have a flat cross-sectional shape and are inclined with respect to the rotational direction. As described above, when the stirring rod R is inserted, the inclined direction of the horizontal blades 8 is an oblique angle with respect to the rotational direction. rotated so that, to assist the penetration of the stirring rod R by generating a downward force component corresponding to the inclination angle of the horizontal wing 8, also at the time of withdrawal is rotated in the direction opposite to that at the time of intrusion of the center pole R _i By doing so, the inclination direction of the horizontal blade 8 becomes an elevation angle with respect to the rotation direction, and the upward component force corresponding to the inclination angle of the horizontal blade 8 is generated to assist the extraction of the stirring rod R. It is desirable to do.

The excavation in the interior of the guide ring 5, as shown in FIG. 4, the drilling blade 10 having an outer diameter enough to close or almost sliding contact with the inner peripheral surface of the drill guide ring 5 with respect to the middle axle R _i, 10 is desirable. By providing the excavating blade 10 that satisfies the above conditions inside the excavation guide ring 5, not only the excavated sediment and solidified material can be mixed in advance, but also the excavated sediment can be excavated in advance. Since the blade 10 plays a role of accurately guiding the penetration of the excavation guide ring 5, it is possible to prevent the bending of the hole more effectively.

  On the other hand, it is desirable to provide screw blades 9 on the outer peripheral surface of the stirring rod R on the upper side of the stirring blades 2 and 2. The screw blade 9 is for reducing the pulling resistance when the stirring rod R is pulled out, and the screw direction is a direction in which the rotating direction at the time of pulling can raise the stirring rod R.

  On the other hand, the discharge of the cement slurry can be arbitrarily switched between a first discharge port 11 provided on the lower surface of the tip of the auger 6 and an upper side position and a lower side position of the stirring blade 2, It is discharged from one of the two portions of 12B.

Switching between the second discharge ports 12A and 12B (12A is the upper side, 12B is the lower side) is performed by a slight structural change to the stirring rod R before the ground improvement is started. Specifically, FIG. 5A is a vertical cross-sectional view when the cement slurry is discharged from the second discharge port 12A at the upper side position of the stirring blade 2. FIG. Inside the center shaft R _i, it is disposed in a state where the upper-side flow pipe 13 and the lower flow pipe 14 is spliced to the flow path forming. The upper-side channel tube 13 has a double-pipe structure, and includes a channel 13a at the center and an annular channel 13b on the outside thereof. The cement slurry to the first discharge port 11 is fed by the flow path 13a of the upper side flow path pipe 13 and the flow path 16 of the lower side flow path pipe 14, and the upper side second discharge opening 12A has the upper part. It is fed by the annular flow path 13 b of the side flow path pipe 13. In addition, the supply path to the lower second discharge port 12B is blocked by the continuous connection of the upper channel pipe 13 and the lower channel pipe 14.

On the other hand, FIG. 5 (B) is a longitudinal sectional view when the cement slurry is discharged from the second discharge port 12B at the lower side position of the stirring blade 2. Inside the center shaft R _i, duct pipe 17 of the double tube for the flow path forming is provided. The flow path pipe 17 is formed concentrically with an inner pipe 17a that forms a flow path to the first discharge port 11, and to a position that closes the discharge port of the upper second discharge port 12A. The cement slurry to the first discharge port 11 is fed by the flow path 18 formed by the inner tube 17a, and is sent to the lower second discharge port 12B. an annular flow path 19a between the inner pipe 17a and the outer tube 17b, is adapted to be fed by an annular channel 19b formed by the inner tube 17a and the inner shaft R _i inner wall.

  In the agitating blade 2 described above, the cement soil is discharged from the two locations of the first discharge port 11 and the second discharge ports 12A / 12B in the intrusion process and / or the pull-up process to the ground, An improved body is created in the ground by mixing with stirring.

It is a front view of the mechanical stirring type ground improvement apparatus 1 which concerns on this invention. It is the side view. It is a top view of the stirring blade part. It is the bottom view. (A) is a longitudinal sectional view showing a flow path configuration when the solidifying material is discharged from the second discharge port 12A, and (B) is a vertical cross section showing a flow path configuration when the solidifying material is discharged from the second discharge port 12B. FIG. It is a side view which shows the conventional ground improvement apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mechanical stirring type ground improvement apparatus, 2 ... Stirring blade, 3 ... Outer stirring blade, 3A ... Radiation frame blade part, 3B ... Dripping frame blade part, 4 ... Inner stirring blade, 5 ... Excavation guide ring, 6 ... Auger, 7 ... 8 Horizontal blades, 9 ... Screw blades, 10 ... Excavation blades, 11 ... First discharge port, 12A and 12B ... Second discharge port, 13 ... Upper channel tube, 20 ... Bearing member, 21 ... Anti-blurring Connecting material, R ... stirring rod, R _O ... outer shaft, R _i ... middle shaft

Claims (5)

A mechanical stirring type ground improvement device that stirs and mixes the discharged solidified material and in-situ soil in the process of entering and / or withdrawing into the ground while rotating a stirring rod having a stirring blade at the tip around the axis. In
The stirring rod has a double tube structure composed of an outer shaft and a middle shaft, and the stirring blade is provided on the outer shaft and rotates in the forward direction together with the outer shaft, and the inner side of the outer stirring blade. An inner stirring blade provided on the middle shaft and rotating in the opposite direction together with the middle shaft,
Said outer stirring blade, a radiation frame wings extending from the outer shaft to the outside, and extending downwardly from the radiation frame wings, the frame wings peripheral comprising a hanging frame wings bent inwardly at the bottom side The excavation guide ring is supported at the tip of the drooping frame wing, and the outer diameter of the excavation guide ring is smaller than the outer diameter of the drooping frame wing of the outer stirring vane. In addition, a drilling bit is provided on the lower surface of the inner bent portion of the drooping frame wing between the outer diameter of the drooping frame wing and the outer diameter of the excavation guide ring, and inside the excavation guide ring, A mechanically agitated ground improvement device provided with an excavating blade having an outer diameter close to or substantially in sliding contact with the inner peripheral surface of the excavation guide ring with respect to an intermediate shaft .   The mechanical stirring type ground improvement device according to claim 1, wherein the radiation frame blade portion of the outer stirring blade has a flat cross-sectional shape and is inclined with respect to the rotation direction. A horizontal wing directed toward the stirring rod is provided on the hanging frame wing portion of the outer stirring wing, and the inner stirring wing is a horizontal wing arranged in a different vertical position from the horizontal wing of the outer stirring wing. The mechanical stirring type ground improvement device according to claim 1 or 2, wherein the horizontal blades have a flat cross-sectional shape and are inclined with respect to the rotation direction. In the upper side of the stirring blade, upon withdrawal of the stirring rod to the outer peripheral surface of the stirring rod, mechanical stirring type ground according to any one of claims 1 to 3, is provided with a screw vane to reduce withdrawal resistance Improved device. The discharge port for the solidification material includes a first discharge port provided at a tip of a stirring rod, and a second discharge port that can be arbitrarily switched between an upper side position and a lower side position of the stirring blade. 1 mechanical stirring type ground improvement device according to any one of 4.

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