JPH07279159A - Ground improving device - Google Patents

Abstract

PURPOSE:To provide a highly reliable ground improving device in which an injecting fluid can be switched without enhancing the diameter and weight of a shaft part. CONSTITUTION:A stirring shaft 1 having a stirring blade 12 within a prescribed range on the lower outer circumference of a shaft part 1A and a screw blade 13 on the shaft part outer circumference of the part having no stirring blade 12 is connected to a driving part 7 supported along a leader mast 2 in such a manner as to be capable of rising and lowering. Two fluid passages are provided in the shaft part IA of the stirring shaft 1, one first fluid passage 14 is allowed to communicate with a first discharge port 15 opened to the shaft part lower end of the stirring shaft 1, and the other second fluid passage 15 is allowed to communicate with a second discharge port 17 opened in the position upper than the range having the stirring blade 12. A fluid supplying source is connected to the first and second fluid passages 14, 15 through a double swivel device 18 provided on the driving part 7, and a switching device 27 for switching the supply of the fluid to the first and second fluid passages 14, 15 is provided in the supplying system between the double swivel device 18 and the fluid supplying source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement device used for improving a ground by injecting a ground improvement material into the ground.

[0002]

2. Description of the Related Art As a ground improvement method for improving soft ground to make it strong ground, ground is excavated and ground improvement material such as cement slurry is poured into the hole and stirred to mix with soil. By hardening this, the ground is firmly improved.

As an apparatus for carrying out the above construction method,
There is a device disclosed in Japanese Patent Application Laid-Open No. 2-140321. This device connects an injection shaft with a stirring blade to the lower part of the auger screw, and selectively improves the ground from the discharge port opened at the lower end and upper side of the injection shaft through the passage in the shaft of the auger screw and the injection shaft. The material is discharged, and the discharge port is selected by a switching device built in the lower position of the shaft part of the auger screw, and the switching operation is performed by the vertical movement of the injection shaft. There is.

[0004]

However, in the above conventional device, since the fluid switching device is provided in the lower portion of the shaft portion of the auger screw, the diameter of the shaft portion incorporating the switching device becomes large, Along with that, the weight also increases,
Moreover, since the switching device is located in the ground during the work, there is a risk of malfunction due to intrusion of sand and water, and it is not possible to confirm whether the switching operation has been performed normally or not, resulting in lack of reliability. There was a problem.

In view of this, it is an object of the present invention to provide a highly reliable ground improvement device which does not increase the diameter of the shaft portion and allows easy confirmation of switching. It is an object of the present invention to provide a ground improvement device capable of grasping a material injection amount in real time.

[0006]

As a means for solving the problems of the above-mentioned conventional techniques, the present invention has a stirring blade in a predetermined range on the outer periphery of the lower portion of the shaft portion, and this stirring blade is not provided. A stirring shaft having screw blades on the outer periphery of the shaft portion is connected to a drive unit that is vertically movable along the leader mast, and two fluid passages are provided in the shaft portion of the stirring shaft. The fluid passage communicates with the first discharge port that opens at the lower end of the shaft of the stirring shaft, and the other second fluid passage communicates with the second discharge port that opens at a position higher than the range where the stirring blade is provided. Then, a fluid supply source is connected to the first and second fluid passages via a double swivel device provided in the drive unit, and a fluid supply system is provided between the double swivel device and the fluid supply source. Switching for switching the supply of fluid to the first and second fluid passages Which is characterized in that a location, according to claim 2, characterized in that it has a flow meter between the double swivel device and switching device, according to claim 3
Is characterized in that an air supply source is connected to the first fluid passage.

[0007]

[Function] Usually, the surface layer of the ground has a relatively hard layer,
Alternatively, since it is often unnecessary to improve the ground, the ground of the non-improved surface layer is excavated while discharging water (or air) from the first discharge port. Water facilitates the excavation of hard ground and air contributes to the efficiency of soil removal by the screw. Select the supply of these fluids according to the properties of the ground,
This is done by operating the switching device.

When the excavation of the non-improved surface layer is exceeded, the excavation proceeds by stopping the fluid discharge from the first discharge port or the second discharge port by switching the switching device. This is to prevent the improved portion, which is a soft formation, from being further softened by the fluid. The excavated earth and sand is discharged to the ground by the screw blade.

When the bottom of the improved portion of the ground is reached, the stirring shaft is pulled up to the upper end of an appropriate depth (doubling portion), and then the changeover device is changed to change the cement slurry or the like (coagulable chemical liquid) from the first discharge port. Discharge and re-excavate to the bottom of the improvement section while stirring and mixing with soil with a stirring blade, and when reaching the bottom of the improvement section, switch the switching device to stop the discharge of fluid (chemical solution) from the first discharge port, Pull up the stirring shaft until the second discharge port is located at the upper end of the doubling section. After that, the discharge from the second discharge port is performed again, and the work is performed up to the non-improved surface layer while stirring and mixing with the soil. When the non-improved surface layer is reached, the outlet from the second outlet is stopped and the stirring shaft is pulled out to the ground.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 is a side view showing an example of the overall structure of the ground improvement device according to the present invention, and FIG. 3 shows a cross section of the stirring shaft 1, which is a leader mast erected on a base machine 2. 3 is supported by a guide rail 4 on the side of 3 so as to be able to move up and down, is connected to an output shaft of a drive unit 7 on which a motor 5, a speed reducer 6 and the like are mounted, and hangs down. It is supported vertically.

In the drive unit 7, the wire 10 wound around the sheave 9 on the upper portion of the drive unit 7 is attached to the sheave 1 on the upper end of the leader mast 3.
1 is guided to a winch (not shown) on the base machine 2, and the drive unit 7 is moved up and down by the hoisting and lowering of the winch, and the stirring shaft 1 is moved up and down.

The stirring shaft 1 is provided with stirring blades 12 and 12 projecting radially in an outer periphery of a predetermined range at a lower end of the shaft portion 1A.
... are provided in a plurality of stages, and the stirring blades 12, 12 are provided.
Screw blades 13 are screwed around the periphery of the shaft portion 1A above the region where the ... Is provided.

Two fluid passages (a first fluid passage 14 and a second fluid passage 15) are provided inside the shaft portion 1A. The first fluid passage 14 is located at the axial center and is located above and below the shaft portion 1A. The first end which penetrates the end and whose lower end opens at the lower end of the shaft portion 1A
It communicates with the discharge port 16. The second fluid passage 15 is located around the first fluid passage 14, and the second fluid passage 15
Is connected to a second discharge port 17 which is opened at a side surface at an upper position in a range where the stirring blades 12, 12, ... Are provided.

The upper parts of the first and second fluid passages 14 and 15 are connected to a double swivel device 18. This double swivel device 18 has seals 19 and 19 on the upper end member 1B of the shaft portion 1A, as shown in FIG.
The first supply pipe 20 is rotatably connected via the, and the first supply pipe 20 and the first fluid passage 14 are always in communication with each other.

An outer casing 21 is provided on the outer periphery of the upper portion of the shaft portion 1A.
Are relatively rotatably fitted to each other via seals 22 and 22, and the opening 23 of the second fluid passage 15 opened to the outer peripheral surface of the shaft portion 1A faces the inside of the outer housing 21. The second supply pipe 24 connected to 21 and the second fluid passage 15 are always in communication with each other.

In the illustrated embodiment, a compressor 25, which is an air supply source, is connected to the first supply pipe 20, and a plant 26, which is a cement slurry (or water) supply source, is connected to the second supply pipe 24. A switching device 27 is provided in the piping system of these supply pipes. In FIG.
Reference numeral 28 is a detent member for fixing the cover of the double swivel device 18 and the connecting pipe 20a of the first supply pipe 20 with bolts 20b.

The switching device 27 has a valve 29 that opens and closes the first supply pipe 20, a valve 30 that opens and closes the second supply pipe 24, and a branch on the upstream side of the valve 30 of the second supply pipe 24. It has a valve 32 for opening and closing a branch pipe 31 that joins the valve 20 of the pipe 20 on the downstream side, and these valves 29, 30, 32 are electromagnetically actuated valves. Note that these valves may be configured as one unit.

In the illustrated embodiment, in order to grasp the injection amount of cement slurry in real time, the downstream side of the branch pipe joining portion of the first supply pipe 20 and the downstream side of the valve 30 of the second supply pipe 24. Flowmeters 33 and 34 are connected to the side, and these valves 29, 30, 32, flowmeter 33,
The control unit 35 is composed of 34.

Next, the operation of the above embodiment will be described. In the surface portion of the ground, there is usually a relatively hard layer or there is no need to improve the ground, so the switching device 27
The valve 29 or 32 is opened, the valve 30 is closed, and water or air is discharged from the first discharge port 16 at the lower end of the stirring shaft 1 while excavating the ground of the surface layer non-improved part A as shown in FIG. . It should be noted that discharging water facilitates excavation of hard ground, and supplying air is effective in increasing the soil discharging efficiency by the screw blades 13. The type and availability of these fluids are selected according to the properties of the ground, and the switching device 27
Operation.

When the excavation of the surface non-improved portion A is exceeded, the first discharge port 16 or the second discharge port 16 is switched by switching the switching device 27.
Exhaust is stopped by stopping the discharge of fluid from the discharge port 17 (FIG. 5 (B)). This is because the improved portion B, which is a soft stratum, is not further softened by the fluid. The excavated earth and sand is discharged to the ground by the screw blade 13.

As shown in FIG. 5 (C), when the stirring shaft 1 reaches the bottom of the improved portion B of the ground, it continues to the upper end position of an appropriate depth (a doubling portion W where shallow excavation is alternately performed). The stirring shaft 1 is pulled up, and then the valve 3 of the switching device 27
2 is opened and the cement slurry is discharged from the first discharge port 16 through the first fluid passage 14, and is stirred and mixed with the sand and sand by the stirring blades 12, 12, ... While re-excavating to the bottom of the improved portion B (Fig. 5 ( D)), when the bottom of the improvement section B is reached, the valve 32 of the switching device 27 is closed to stop the discharge of the cement slurry from the first discharge port 16, and the second discharge port 17 is located at the upper end position of the doubling section W. The stirring shaft 1 is pulled up to (Fig. 5 (E)).

After that, the cement slurry is again discharged from the second discharge port 17, and the work is carried out to the surface layer non-improved portion A while stirring and mixing with the soil (FIG. 5 (F)). When the surface non-improved part A is reached, the discharge of the cement slurry from the second discharge port 17 is stopped, the stirring shaft 1 is pulled out to the ground, and the work is finished (FIG. 5 (G)).

The discharge amount of the cement slurry in the above work is detected by the flow meters 33 and 34, and when the amount is different from the planned amount, the supply amount is adjusted.

[0024]

As described above, according to the present invention, the switching device for switching the fluid supplied to the ground through the two fluid passages in the agitation shaft is above the agitation shaft. Since it is provided at a position that is not directly related to it, it is possible to easily confirm the switching, improve the reliability of the work, and prevent the diameter of the stirring shaft from increasing, thereby preventing the weight from increasing.

If a flow meter is provided in the fluid supply system as in claim 2, the injection amount of the chemical liquid such as cement slurry can be grasped in real time, and the accuracy of the pile can be improved.

If a switching device is attached to the drive unit as in the illustrated embodiment, it is effective in reducing the time lag between switching and discharge.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an overall configuration example of a ground improvement device according to the present invention.

FIG. 2 is an enlarged view of a drive unit in FIG.

FIG. 3 is a partially cutaway sectional view showing a stirring shaft and a fluid supply system according to the present invention.

FIG. 4 is an enlarged sectional view of the double swivel device in FIG.

5 (A) to (G) are explanatory views showing a mode during stirring and mixing.

[Explanation of symbols]

 1 Stirring Shaft 3 Leader Mast 7 Drive Unit 12 Stirring Blade 13 Screw Blade 14 First Fluid Passage 15 Second Fluid Passage 16 First Discharge Port 17 Second Discharge Port 18 Double Swivel Device 20 First Supply Pipe 21 Outer Housing 23 Opening 24 Second supply pipe 25 Air supply source (compressor) 26 Plant 27 Switching device 29, 30, 32 Valve 33, 34 Flow meter 35 Control unit

Claims (3)

[Claims] 1. A stirring shaft having a stirring blade in a predetermined range on the outer periphery of the lower portion of the shaft portion and having screw blades on the outer periphery of the shaft portion where the stirring blade is not provided can be moved up and down along a leader mast. And a two-way fluid passage is provided in the shaft portion of the stirring shaft. One of the first fluid passages communicates with a first discharge port opened at the lower end of the stirring shaft. The other second fluid passage communicates with a second discharge port that is opened at a position higher than the range where the stirring blade is provided,
A fluid supply source is connected to the first and second fluid passages through a double swivel device provided in the drive unit, and a first supply system is provided between the double swivel device and the fluid supply source. ,
A ground improvement device comprising a switching device for switching the supply of fluid to the second fluid passage. 2. The ground improvement device according to claim 1, further comprising a flow meter between the double swivel device and the switching device. 3. The ground improvement device according to claim 1, wherein an air supply source is connected to the first fluid passage.