JPH04222712A - Method and apparatus for improving soft ground - Google Patents

Abstract

PURPOSE:To uniformly mix excavated soil with a hardener effectively by a method in which upper and lower rotary plates turning with an inner tube are combined with upper and lower stirring plates moving vertically with an outer tube. CONSTITUTION:Upper and lower stirring plates 11 having openings 13 are attached to the tip of an outer tube 3 attached in a vertically movable manner to an elevator base 2. A lower rotary stirring plate 12 having openings 14 is attached to the tip of an inner tube 4 inserted into the tube 3, and a cylindrical wall 17 provided with upper rotary stirring plates 19 having openings 20 is attached to the periphery of the plate 12. While turning the tube 4 with the plates 12 and 19 and excavating blade 16 of the excavator, a hardener is jetted from the tip. At the same time, the tube 3 is vertically moved with the plate 11 and a complicated disturbing action is brought about by combination with rotation of the plates 12 and 19, thereby mixing the excavated soil and the hardener with stirring.

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] The present invention provides a lower part in which a plurality of openings are provided at the tip of an inner tube that is rotatably inserted into an outer tube that is vertically movably attached to a lifting platform and protrudes from the tip of the inner tube. A rotating stirring plate is attached, and a cylindrical wall rising upward is provided on the outer periphery of the lower rotating stirring plate, and at the upper end of this cylindrical wall is an annular plate that rotatably surrounds the outer tube. A lid plate with a plurality of openings is provided, and an annular vertical stirring plate with a plurality of openings is attached to the lower outer periphery of the outer tube surrounded by the cylindrical wall. A rotary agitation plate is provided on the peripheral surface of the annular plate that rotatably surrounds the outer tube and has a plurality of openings on the annular surface, and an excavation blade is attached to the lower side of the lower rotary agitation plate. Using a drilling device, the inner tube is rotated and the hardening material is injected from the tip thereof while drilling with the drilling blade, and at the same time, the outer tube is moved up and down together with the upper and lower stirring plates, and the outer tube is moved up and down together with the lower rotating stirring plate and This invention proposes a soft ground improvement method characterized by stirring the excavated earth and sand inside the cylindrical wall by rotating a rotating stirring plate and vertically moving the vertical stirring plate.

[0009]

[Operation] The inner tube is rotated together with its lower rotating stirring plate and the cylindrical wall, and the hardening material is injected from the injection hole at the tip of the inner tube while excavating with the drilling blade.At the same time, the outer tube is moved up and down with its vertical stirring plate. The rotation of the rotating stirring plate that rotates together with the lower rotating stirring plate and the cylindrical wall causes the excavated earth and sand to rotate and flow within the cylindrical wall, and the vertical movement of the vertical stirring plate causes the excavated earth and sand to flow up and down through the opening, and the cylindrical wall A complex turbulent agitation action caused by repetition of rotational flow and up-and-down flow that occur simultaneously inside the hole allows the soil to be stirred and mixed evenly and efficiently from the center of the borehole to the periphery, ensuring a homogeneous improved ground. can get.

[0010] Since the above-mentioned stirring and mixing is performed inside the cylindrical wall, unimproved soil is prevented from dissipating to the surrounding area, and unimproved soil is prevented from mixing into adjacent improved areas or collapsing and invading from adjacent improved areas. It is possible to prevent such troubles.

[0011]

[Embodiment] First, the construction device of the present invention will be explained. As shown in Figs. 1 and 2, an elevating platform 2 attached to a leader 1 installed on a mobile vehicle such as a crawler so as to be able to be moved up and down is A 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 rotatably supported on the side surface of the lifting platform 2, and
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 7 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.

One or more annular vertical stirring plates 11 shown in FIG. 3 are attached to the outer periphery of the tip of the outer tube 3, and an annular lower part shown in FIG. 5 is attached to the tip of the inner tube 4. A rotating stirring plate 12 is attached, and the upper and lower stirring plates 11 and the lower rotating stirring plate 12 are provided with openings 13, respectively, for the circulation of excavated soil.
There are multiple numbers 14.

As shown in FIG. 6, 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.

A digging blade 16 is attached to the lower surface of the lower rotary stirring plate 12, and a cylindrical wall 17 with an outer diameter slightly smaller than the outside diameter of the digging blade 16 stands upward on the outer periphery, and the outer tube 3 is It is installed so as to surround the lower periphery. In addition,
The excavating blade 16 may be provided on the lower surface of an excavating arm radially attached to the outer periphery of the inner tube 4 below the lower rotary stirring plate 12.

At the upper end of the cylindrical wall 17, there is provided a cover plate 18, which is an annular plate that rotatably surrounds the outer tube 3 and has a plurality of openings on its annular surface. Outer tube 3
A vertical agitation plate 11 is fitted to be vertically movable, and an upper rotating plate made of an annular plate rotatably surrounding the outer tube 3 is attached to the inner peripheral surface of the cylindrical wall 17 above the vertical agitation plate 11. One or more stirring plates 19 are attached.

As shown in FIG. 4, the upper rotating stirring plate 19 has a plurality of openings 20 for soil circulation on its annular surface, and stirring blades 21 on its lower surface.

A discharge port 22 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.

Next, a construction method for performing ground improvement work using the construction device with the above configuration will be explained.
While rotating the inner tube 4 and drilling a hole with the drilling blade 16, the hardening material is discharged from the discharge hole 22 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 16 is mixed with water by stirring to become muddy water, and the lower rotating stirring plate 1 rotates.
The stirring blades 2 of the lower rotating stirring plate 12 and the upper rotating stirring plate 19 flow into the cylindrical wall 17 through the opening 14 of 2 and rotate.
1 causes swirling flow, and also 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 this swirling flow and up-and-down flow, the cylindrical wall together with the hardening material 17, the entire mixture is stirred and mixed efficiently and uniformly.

In this case, by providing a bent flow guide plate 15 around the periphery of the opening 13 of the vertical stirring plate 11, 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, by providing a plurality of vertical stirring plates 11 and upper rotating stirring plates 19, stirring and mixing can be repeated in the upper and lower portions of the cylindrical wall 17, thereby making it possible to stir more reliably.

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.

[0026] The above-mentioned construction is successively carried out adjacent to the surrounding area to improve the entire ground.

The stirring operation by the rotation of the upper rotary stirring plate 19 and the vertical movement of the vertical stirring plate 11 may be performed after drilling is completed, if necessary.

[0028]

As described above, according to the present invention, the earth and sand excavated by the excavation blade flows into the cylindrical wall through the opening of the rotating lower rotating stirring plate, and inside the cylindrical wall, the earth and sand are moved by the upper and lower rotating stirring plates. As well as being made to swirl, it also flows up and down through the opening of the vertical stirring plate that moves up and down repeatedly, and due to the complex turbulent flow effect caused by the combination of this swirling flow and up and down flow, the hardened material is removed from the center of the drilling hole. Stirring and mixing can be carried out efficiently and uniformly in all directions in the periphery.

Furthermore, since such agitation and mixing is carried out inside the cylindrical wall, unimproved soil is prevented from dissipating into the surrounding area, and unimproved soil is prevented from getting mixed into adjacent improved areas or soil from adjacent improved areas. Trouble such as collapse and invasion can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view showing one aspect of the construction state of the present invention.

FIG. 2 is a longitudinal side view showing another aspect of the construction state 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 the upper rotating stirring plate according to the apparatus of the present invention.

FIG. 5 is a plan view of a lower rotating stirring plate according to the apparatus of the present invention.

FIG. 6 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.

[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 Lower rotating stirring plate 13 Opening 14 Opening 15 Flow guide plate 16　Drilling blade stirring blade 17 Cylindrical wall 18 Lid plate 19 Upper rotating stirring plate 20 Opening 21 Stirring blade 22 Discharge port

Claims (3)

[Claims] Claim 1: A lower rotary stirring plate provided with a plurality of openings is attached to the tip of an inner tube that is rotatably inserted into an outer tube that is attached to a lifting platform so as to be movable up and down and protrudes from the tip of the inner tube, A cylindrical wall rising upward is provided on the outer periphery of the rotating stirring plate, and a lid plate is provided at the upper end of the cylindrical wall, which is an annular plate that rotatably surrounds the outer tube and has a plurality of openings in the annular surface. An annular vertical stirring plate with a plurality of openings is attached to the lower outer circumference of the outer tube surrounded by the cylindrical wall, and a ring-shaped vertical stirring plate with a plurality of openings is attached to the inner peripheral surface of the cylindrical wall above the vertical stirring plate. Using an excavation device consisting of a rotatable agitation plate that is rotatably surrounding the circumference and has a plurality of openings on the annular surface, and an excavation blade attached to the lower side of the lower rotary agitation plate, the inner pipe is is rotated to inject hardening material from its tip while drilling with the drilling blade, and at the same time, the outer tube is moved up and down together with the upper and lower stirring plates, thereby rotating the lower rotating stirring plate and the rotating stirring plate and rotating the upper and lower rotating stirring plates. A soft ground improvement method characterized by stirring the excavated earth and sand inside the cylindrical wall by vertical movement of a stirring plate. 2. An inner tube rotatably supported on the lifting table via a rotary drive device is inserted into an outer tube supported vertically on the lifting table via a vertical drive device, and the tip of the outer tube is A lower rotating stirring plate with a plurality of openings is attached to the tip of the inner tube protruding from the inner tube, a cylindrical wall rising upward is provided on the outer periphery of the lower rotating stirring plate, and the outer tube is attached to the upper end of the cylindrical wall. An annular plate that rotatably surrounds a tube, a lid plate with a plurality of openings provided on the annular surface, and a plurality of openings provided on the lower outer periphery of the outer tube surrounded by the cylindrical wall. A rotating stirring plate is provided with a vertical stirring plate attached to the inner circumferential surface of the cylindrical wall above the vertical stirring plate, which is an annular plate that rotatably surrounds the outer tube, and has a plurality of openings in the annular surface. , and a digging blade is attached to the lower side of the lower rotating stirring plate,
A soft ground improvement device characterized in that a hardening material injection hole is provided at the tip of the inner pipe. 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.