JPH04222711A - Method and apparatus for improving soft ground - Google Patents

Abstract

PURPOSE:To uniformly mix excavated soil with a hardener by stirring effectively over the peripheral side from the central part of a pit excavated. CONSTITUTION:A vertical stirring plate 11 having openings 13 is attached to the tip of an outer tube 3 attached in a vertically movable manner to an elevating base 2. A rotary stirring plate 12 having openings 14 is attached to the tip of an inner tube 4 inserted into the tube 3 and an excavating blade 17 is also provided on the lower part of the plate 12 in an excavator. While turning the tube 4 with the blade 17 and the plate 11, a hardener is jetted from the tip, and at the same time the tube 3 is vertically moved with the plate 11 to agitate excavated soil by rotation of the plate 12 and vertical action of the plate 11.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a method for improving soft ground, and in particular to a method for improving soft ground into a composite ground by mechanically mixing and stirring soft soil and hardening material and hardening it into a cylindrical shape. be.

0002

[Prior Art] Conventionally, as a method of improving soft soil by mechanically mixing and agitating it while injecting a hardening agent, mainly cement milk, from the tip of a single-shaft stirring rod, the Various stirring methods are known, such as rotating plate-shaped stirring blades installed adjacent to each other in forward and reverse directions, rotating similar stirring blades in the same direction at different speeds, and using blade-cut stirring using anti-co-rotation blades. It is being

However, the above conventional stirring method has the following problems.

(a) Since the spacing between adjacent stirring blades is fixed, if the axial area of the blades is large or if the soil clod is large, the force of the excavated soil that tries to rotate together will be large and the shaft will be forced to move. On the other hand, if the axial area of the blades is narrow, the stirring blades rotate through the soil with the soil divided into upper and lower parts, resulting in insufficient stirring effects.

(b) In the method of stirring by blade-cutting motion, the soil instantaneously becomes finer at the part where the blades pass each other, and attempts to mix and stir the soil with the hardening material, so depending on the case, the soil must be repeated up and down many times. It will not be possible to mix sufficiently unless you repeat the process repeatedly.

[0006] C) If only the rotational motion of a single shaft is used, the stirring effect between the center and the circumference of the column to be improved will be uneven, and there is a risk that the degree of improvement will vary.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problem that the above-mentioned conventional stirring by mere rotation of stirring blades is insufficient in stirring effect.

[0008]

[Means for Solving the Problems] This invention provides a method for rotating and stirring the inner tube by attaching a vertical stirring plate and a rotating stirring plate each having a plurality of openings to the tip of an outer tube and an inner tube inserted into the inner tube. At the same time as it rotates with the plate, the outer tube is moved up and down together with its vertical agitation plate, and while hardening material is injected from the injection hole at the tip of the inner tube, the excavated soil is rotated and flowed by the rotation of the rotary agitation plate, and the excavated soil is agitated up and down. The present invention proposes a means in which excavated earth and sand are caused to flow up and down through the openings by vertical movement of the plate.

[0009]

[Operation] The rotation of the rotating stirring plate causes the excavated soil to rotate and flow, and the vertical movement of the vertical stirring plate causes the excavated soil to flow up and down through its opening, creating a complex turbulent flow due to the repetition of rotational flow and up-and-down flow that occur at the same time. The stirring action uniformly and efficiently stirs and mixes the earth and sand from the center of the borehole to the periphery, ensuring homogeneous improved ground.

0010

[Embodiment] First, the construction device of the present invention will be explained. Figs. 1 and 2 show a first embodiment in which a lifting platform 2 is attached to a leader 1 installed in a mobile vehicle such as a crawler so as to be able to move up and down. , an outer tube 3 and an inner tube 4 inserted therein are supported.

The outer tube 3 is connected to the lifting platform 2 by a vertical drive device 5.
The inner tube 4 is supported so as to be movable up and down in the axial direction within a required length range, and the inner tube 4 is rotatably supported by a rotary drive device 6 using a motor.

The vertical drive device 5 includes a crank disk 7 that is rotatably supported on the side surface of the lifting table 2, and a crank disk 7 that is
from a motor 9 which is rotationally driven via a power transmission mechanism 8 such as a sprocket chain, and a crank arm 10 whose upper end is eccentrically pivotally connected to the crank disc 7 and whose lower end is pivotally connected to the upper outer periphery of the outer tube 3. By driving the motor 9, the crank disc 6 is rotated and the crank arm 1 is rotated.
The outer tube 3 is configured to move up and down at high speed via the outer tube 3.

As the vertical drive device 5, a rack is provided on the outer circumference of the outer tube 3 in the axial direction thereof, and a pinion gear meshed with the rack and rotated by a motor is provided on the lifting platform 2.
By rotating this pinion gear in forward and reverse directions, various other vertical drive devices such as a mechanism for vertically moving the outer tube 3 can be used.

A vertical stirring plate 11 made of an annular plate shown in FIG. 3 is attached to the outer periphery of the tip of the outer tube 3, and an annular plate 11 made of an annular plate shown in FIG. 4 is attached to the tip of the inner tube 4. A rotating stirring plate 12 is attached, and the vertical stirring plate 11 and the rotating stirring plate 12 have openings 13 and 1 for the circulation of excavated soil, respectively.
4 has been revealed multiple times.

As shown in FIG. 5, a part of the periphery of the opening 13 of the vertical stirring plate 11 has a hook-shaped, arc-shaped, or sloped cross-section bent upward or downward on the surface of the vertical stirring plate 11. A flow guide plate 15 is provided.

The rotating stirring plate 12 has stirring blades 1 on its upper surface.
6, and a digging blade 17 is attached to the lower surface. The excavating blade 17 may be provided on the lower surface of an excavating arm radially attached to the outer periphery of the inner tube 4 below the rotating stirring plate 12.

A discharge port 18 is provided at the tip of the inner tube 4 for discharging a soil hardening material such as cement milk that is pumped through the interior from above.

In the second embodiment shown in FIGS. 6 and 7,
A cylindrical wall 19 is provided on the outer periphery of the rotating stirring plate 12 and stands upward within the range in which the vertical stirring plate 11 moves up and down.

Next, a construction method for performing ground improvement work using the construction device having the above configuration will be explained.
While rotating the inner tube 4 and drilling a hole with the drilling blade 17, the hardening material is discharged from the discharge hole 18 at the tip.
The outer tube 3 is moved up and down at high speed by a vertical drive device 5.

The earth and sand excavated by the excavation blade 17 is scraped up and flows upward through the opening 14 of the rotating stirring plate 12, and is swirled and fluidized by the stirring blade 16 of the rotating stirring plate 12. It flows up and down through the opening 13 of the vertical stirring plate 11 that moves up and down repeatedly, and due to the complex turbulent flow effect caused by the combination of the swirling flow and the up-and-down flow, the hardened material flows from the center of the hole to the periphery. The mixture is efficiently and uniformly stirred and mixed vertically and horizontally.

In this case, by providing a bent flow guide plate 15 around the periphery of the opening 13 of the vertical stirring plate 12, the opening 1
3, the earth and sand bends and flows, generating a vortex, which creates more complex turbulence, making it possible to further enhance the stirring effect.

Furthermore, in the second embodiment shown in FIGS. 6 and 7, as a result of the stirring by the rotating stirring plate 12 and the vertical stirring plate 11 being carried out within the cylindrical wall 19, unimproved soil flows into the adjacent improved ground. It is possible to prevent problems such as dissipation and contamination of soil from adjacent improved ground.

In this way, the above-mentioned stirring and mixing is repeated and continued while drilling to the planned depth, and after stirring and mixing the excavated earth and sand uniformly as a whole, the lifting platform 2 is moved together with the outer pipe 3 while the inner pipe 4 is reversed. It is raised and pulled up, and then the hardened material is hardened to create soil pillars.

[0024] The above-mentioned construction is successively carried out adjacent to the surrounding area to improve the entire ground.

The stirring operation by rotating the rotary stirring plate 12 and moving the vertical stirring plate 11 up and down may be performed after drilling is completed, if necessary.

[0026]

As described above, according to the present invention, the earth and sand excavated by the excavation blade flows upward through the opening of the rotating stirring plate, is made to swirl and flow by the rotating stirring plate, and is repeatedly It flows up and down through the opening of the vertical stirring plate that moves up and down, and due to the complex turbulent flow caused by the combination of this swirling flow and up and down flow, the hardened material flows vertically and horizontally from the center of the hole to the periphery. Stirring and mixing can be performed efficiently and uniformly.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing one aspect of a construction state in a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing another aspect of the construction state in the first embodiment of the present invention.

FIG. 3 is a plan view of a vertical stirring plate according to the apparatus of the present invention.

FIG. 4 is a plan view of a rotating stirring plate according to the apparatus of the present invention.

FIG. 5 is a longitudinal sectional side view of the opening portion of the upper and lower stirring plates according to the apparatus of the present invention.

FIG. 6 is a vertical sectional side view showing one aspect of the construction state in the second embodiment of the present invention.

FIG. 7 is a vertical sectional side view showing another aspect of the construction state in the second embodiment of the present invention.

[Explanation of symbols]

1 Leader 2 Lifting platform 3 Outer tube 4 Inner pipe 5 Vertical drive device 6 Rotation drive device 7 Crank disc 8 Power transmission mechanism 9 Motor 10 Crank arm 11　Upper and lower stirring plate 12 Rotating stirring plate 13 Opening 14 Opening 15 Bent flow guide plate 16 Stirring blade 17 Drilling blade 18 Discharge port 19 Cylindrical wall

Claims (4)

[Claims] Claim 1: A vertical stirring plate consisting of an annular plate with a plurality of openings is attached to the tip of an outer tube that is vertically movably attached to a lifting platform, and a vertical stirring plate is attached to the tip of an inner tube inserted into the outer tube. ,
Using an excavation device consisting of a rotating stirring plate consisting of a circular annular plate with a plurality of openings and a digging blade attached to the bottom thereof, the hardened material is removed from the tip of the inner tube while rotating together with the digging blade and the rotating stirring plate. A soft ground improvement method characterized in that the outer tube is simultaneously moved up and down together with the vertical stirring plate, and the excavated soil is stirred by the rotation of the rotating stirring plate and the vertical movement of the vertical stirring plate. 2. A vertical stirring plate made of an annular plate with a plurality of openings is attached to the tip of an outer tube that is attached to the lifting table so as to be able to move up and down via a vertical drive mechanism, and the lifting table is rotatably driven. A rotary agitation plate consisting of an annular plate with a plurality of openings is attached to the distal end of the inner tube which is rotatably attached via a mechanism and inserted into the outer tube, and a digging blade is attached to the lower side of the rotating stirring plate. A soft ground improvement device characterized by having a hardening material injection hole at the tip. 3. The soft ground improvement device according to claim 2, wherein the vertical stirring plate has a bending flow guide plate vertically protruding from a part of the periphery of the opening thereof. [Claim 4] The soft ground according to claim 2 or claim 3, wherein the rotating stirring plate is provided with a cylindrical wall rising upward in the range in which the vertical stirring plate moves up and down, on its outer periphery. Improved equipment.