JPH0835225A - Excavation and agitation device for soil improvement - Google Patents

Abstract

PURPOSE:To improve the quality of a ground-improving column, by reducing the water content given from the peripheral ground, on constructing the ground- improving column in a soft ground. CONSTITUTION:An excavating edge 2 is formed at the lower end of a steel pipe 1 having a length and a diameter corresponding to a ground-improving colums expected to construct. The upper end of a hollow rod 4 having a nozzle 3 ejecting cement milk is fixed at the front end, in the steel pipe 1. Excavating arms 6 provided with cutter blades 7 at the underface are protruded radially at the lower end of the hollow rod 4. The front end 8 of cutter blades 7 are positioned near the lower end of the steel pipe 1 and positioned above the excavating edge 2. A connection part with an auger machine is provided at the upper end of the hollow rod. Rotary agitation blades 10 are rotatably fitted to the hollow rod through a support cylinder 11. Agitation bars 12 are parallelly arranged at every specified vertical distance, symmetrically in the diametral direction to constitute an excavation and agitation device 14 for ground improvement. The vertically adjacent agitation bars 12 are fixed in different phases from one another.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavating and stirring device for ground improvement on soft ground.

[0002]

2. Description of the Related Art Conventionally, for improvement of ground, an improved pillar was constructed by advancing with a drilling rod equipped with a stirring bar and mixing a ground improving agent such as cement milk.

[0003]

The conventional excavating rod has a problem in that it is thinned at the boundary between the portion filled with the ground improvement agent and the surrounding ground, resulting in deterioration of the quality of the improved column.

[0004]

According to the present invention, however, the above-mentioned problems are solved because the hollow rod having the drilling blade and the stirring bar projecting therefrom is fixed in the steel pipe.

That is, according to the present invention, a hollow rod having a cement milk discharge port at its lower end is fixed in a steel pipe having a digging edge at its lower edge, and a connecting portion with a rotary drive device is provided at the upper end of said hollow rod. The excavation and agitation device for ground improvement is characterized in that an excavation blade is provided at a lower end portion and an agitation bar is provided at an intermediate portion.

Further, in the excavation and agitation device for ground improvement, a stirring blade, which is rotatable and restricted in vertical movement, is installed above the excavation blade at the lower end of the hollow rod. Further, the excavating blade and the stirring bar provided on the hollow rod are the excavating and stirring device for ground improvement in which vertically adjacent ones are installed with their phases shifted from each other. Further, the excavating blade is an excavating and stirring device for ground improvement, which is located near the lower end of the steel pipe and does not project downward from the lower end of the steel pipe.

[0007]

Since the hollow rod having the excavating blade protruding is fixed in the steel pipe having the excavating edge at the lower edge, it is possible to advance by excavating the hollow rod. Since the stirring rod is projected on the hollow rod, the excavated soil in the steel pipe is agitated, and the cement milk discharged from the discharge port is uniformly mixed with the excavated soil. In addition, since the excavated soil is agitated and mixed in the steel pipe, it is possible to significantly reduce the mixing of water from the surrounding ground into the excavated soil.

Further, when the excavating blade is located near the lower end of the steel pipe and is located so as not to project from the lower end of the steel pipe, the excavating blade is less loaded during excavation.

[0009]

Embodiment 1 An embodiment of the present invention will be described with reference to the drawings.

The lower edge of the steel pipe 1 having a length and diameter corresponding to the ground improvement column to be constructed is thick, and the lower edge is a corrugated excavation edge 2. A hollow rod 4 having a nozzle (discharge port) 3 for discharging cement milk at the tip is arranged in the steel pipe 1 along the central axis, and the upper end 5 of the hollow rod 4 is provided at the upper end of the inner wall 1a of the steel pipe. Are fixed via the support members 15, 15. Excavating arms 6, 6 are radially provided on the lower end of the hollow rod 4, and excavating blades 7, 7 are provided on the lower surface of the excavating arm 6 so as to be inclined forward in the rotational direction.
The tip 8 of the excavating blade 7 is located near the lower end of the steel pipe 1 (excavation edge 2) and the lower edge of the steel pipe 1 (excavation edge 2).
It is located above. Further, above the position where the support member 15 is fixed at the upper end portion of the hollow rod 4, a connecting portion (not shown) for connecting to an auger machine (rotary driving device) is provided.

Further, the hollow rod 4 allows the excavating arms 6, 6
A support cylinder 11 is rotatably fitted immediately above the support cylinder 11, and the rotary stirring blades 10 and 10 are fixed to the support cylinder 11. The support cylinder 11 of the rotary stirring blades 10 and 10 is restricted in vertical movement by stoppers 9 and 9 fixed to the hollow rod 4. The rotary agitating blades 10 and 10 are rectangular plate-shaped and are provided so as to project diametrically symmetrically, and when the hollow rod 4 rotates forward (in the direction of arrow 16 in FIG. 1B), the side 10a located on the front side.
Is installed on the lower side, and the side 10b located on the rear side is installed so as to be the upper side. Also, with the hollow rod 4,
Between the upper end and the position where the rotary stirring blade 10 is installed, the stirring bars 12 and 12 are diametrically symmetrically provided. The stirring bars 12 and 12 are arranged in parallel in the vertical direction with a predetermined interval. The stirring bar 12 is a long and narrow rectangular plate,
When the hollow rod 4 rotates forward (16 directions indicated by an arrow in Fig. 1 (b))
In addition, the side 13 located on the front side is installed on the lower side and the side 13a located on the rear side is installed on the upper side. The stirring bars 12 and 12 are fixed to the hollow rod 4 with the stirring bars 12 vertically adjacent to each other in a different phase.

The excavation and agitation device 14 for ground improvement is constructed as described above (FIGS. 1 (a) and 1 (b)).

Next, the use of the excavation and agitation device 14 will be described.

The hollow rod of the excavator and agitator 14 is connected to an auger machine (rotary drive device, not shown), and the lower edge of the steel pipe 1 of the excavator and agitator 14 is placed on the ground 17 of the ground to be improved. To match. The auger machine is operated to rotate the excavation and agitation device 14 in the direction of arrow 16. Since the excavation edge 2 is formed on the lower edge of the steel pipe 1, the steel pipe 1 is lowered while rotating by the rotation of the hollow rod 4, and at the same time, the inside of the steel pipe 1 is excavated by the excavation blade 7 of the hollow rod 4 (FIG. 2). ). In the above description, since the digging blades 7 and 7 are located near the lower end of the steel pipe 1 and do not protrude from the lower end of the steel pipe 1, the load on the digging blade 7 during digging is small and the digging edge 2 of the steel pipe 1 is We can excavate efficiently in cooperation.

When the digging blade 7 reaches a predetermined depth (about 1 m), the amount of water is adjusted from the nozzle 3 of the hollow rod 4 (for example, 50 to 70%) while the cement milk is discharged slowly. And proceed. The excavated soil is excavated in the steel pipe 4 by excavating arms 6, 6, rotating stirring blades 10, 10, stirring bar 1
2,12 stirred with cement milk. In the above description, the rotary stirring blade 10 is installed so as to be inclined so that the front side 10a is on the lower side and the rear side 10b is on the upper side during forward rotation. The flow rotates to stir the excavated soil. Further, in the above description, the stirring bar 12 is installed in a phase different from that of the stirring bars 12 that are vertically adjacent to each other.

When the excavation and stirring is completed to a predetermined depth (FIG. 3), the auger machine is operated and the excavation and stirring device 14 is pulled up while the excavation and stirring device 14 is rotated in the reverse direction. The excavated soil is stirred while being pulled up. After pulling up, steel pipe 1
The excavated soil inside is solidified, and the ground improvement pillar 18 is constructed. At this time, since the inside of the steel pipe 1 is not easily affected by moisture or the like from the surrounding ground, the shape can be determined. Therefore, the ground improvement pillar 18
It is possible to construct improved columns that are almost homogeneous even at the periphery of the.

In the above description, since the excavation and agitation device 14 has only one rotating shaft, it can be attached to any auger machine, and is thus highly versatile. Further, in the above description, the cement milk is discharged from the nozzle 3 after reaching a predetermined depth, but the cement milk can be discharged at the same time as the start of excavation, and the discharge start timing depends on the characteristics of the ground.

In the above-mentioned embodiment, two rotary stirring blades 10 and stirring bars 12 are diametrically symmetrically provided at the same height, but three or four or more may be provided at equal intervals. In addition, different numbers of rotary stirring blades 10 and stirring bars 12
Can be mixed.

Further, in the above embodiment, the rotary stirring blade 1
Although 0 is rotatable, it can be fixed to the hollow rod 4 like the stirring bar 12.

[0020]

EFFECTS OF THE INVENTION Since the hollow rod having the digging blade protruding is fixed in the steel pipe having the digging edge at the lower edge, the hollow rod can be rotated for efficient digging. Further, since the stirring bar is provided on the hollow rod, the excavated soil is stirred and mixed with the cement milk in the steel pipe, so that there is an effect that a uniform ground improvement column can be constructed. Further, since the mixing of water from the surrounding ground can be significantly reduced, it is easy to manage the water content of the ground improvement pillar, and there is an effect that a good ground improvement pillar can be constructed.

[Brief description of drawings]

FIG. 1 is an embodiment of a drilling and stirring apparatus of the present invention, (a) is a front view in which a steel pipe is broken, and (b) is a sectional view taken along line AA of FIG. 1 (a).

FIG. 2 shows excavation and agitation in the use state of the present invention,
It is the front view which ruptured the steel pipe.

FIG. 3 is a front view in which the steel pipe is broken and represents a state in which excavation and stirring are completed to a predetermined depth in the same use state.

FIG. 4 is a front view in which the steel pipe is broken, showing a state in which the excavation and agitation device is pulled out and the construction of the soil improvement column is completed in the same use state.

[Explanation of symbols]

 1 Steel Pipe 2 Excavation Edge 1a (Steel Pipe) Inner Surface 3 Nozzle (Discharge Port) 4 Hollow Rod 6 Excavation Arm 7 Excavation Blade 8 Tip (of Excavation Blade) 10 Rotating Stirring Blade 12 Stirring Bar 14 Excavation Stirrer 17 Ground 18 Ground Improvement Column

Claims (4)

[Claims] 1. A steel rod having a digging edge at a lower edge thereof, wherein a hollow rod having a cement milk discharge port at its lower end is fixed, and a connecting portion with a rotary drive device is provided at an upper end portion of the hollow rod.
An excavation and agitation device for ground improvement, comprising an excavation blade projecting from a lower end and a stirring bar projecting from an intermediate part. 2. The excavation and agitation device for ground improvement according to claim 1, wherein a stirring blade, which is rotatable and restricted in vertical movement, is installed above the excavation blade at the lower end of the hollow rod. 3. The excavation and agitation device for ground improvement according to claim 1, wherein the excavation blade and the agitation bar provided on the hollow rod are vertically adjacent to each other and are out of phase with each other. 4. The excavating blade is located near the lower end of the steel pipe, and does not project downward from the lower end of the steel pipe.
An excavation and agitation device for ground improvement as described.