JP3569853B2 - Ground improvement method and its equipment - Google Patents

Description

[0001]
[Industrial applications]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep mixing method and an apparatus therefor among ground improvement methods.
[0002]
[Prior art]
Conventionally, as a ground improvement method for improving the ground by forming a hardened body in the ground by mixing the soil and the solidified material in the ground, as the stirring shaft penetrates to the ground to be improved, the shaft of the stirring shaft is 2. Description of the Related Art A deep-layer mixing method of mixing a soil and a solidified material in a slurry or powder state by stirring with a stirring blade provided to form a hard solid in the ground is widely used.
[0003]
[Problems to be solved by the invention]
However, this method has the following problems.
(1) Unimproved part is formed at the tip of the improvement area (2) Non-uniformity of improvement strength due to uneven mixing (3) Poor mixing due to co-rotation of agitating blade and soil (4) Surrounding ground due to increased volume of ground Various measures have been taken to solve these problems.
[0004]
To give a typical example of the above measures,
{Circle around (1)} As a countermeasure against the occurrence of an unimproved portion at the tip of the improvement range, there is a method of providing upper and lower solidified material discharge ports at the tip of the stirring shaft and switching the discharge ports to improve the tip of the improvement range. is there.
{Circle around (2)} A method of changing the shape of the stirring blade to eliminate uneven mixing in order to eliminate uneven strength due to uneven mixing.
(3) A method of providing a counter-rotating plate as a countermeasure against poor mixing due to co-rotation of the stirring blade and soil.
(4) The displacement of the surrounding ground due to the increase in the ground volume is controlled by removing the soil with a screw auger.
And so on.
However, these methods increase the cost due to an increase in the size of the apparatus or the complexity of the mechanism, and may not be effective depending on the soil properties, and thus cannot be said to have solved the problem.
It is an object of the present invention to provide a ground improvement method and an apparatus for solving these problems by a simple and economical method.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention penetrates the stirring shaft to a predetermined depth of the planned improvement range in the ground, and further, simultaneously discharges the solidified material from the discharge ports provided at the upper and lower portions of the stirring blade at the tip of the stirring shaft. After the stirrer shaft is penetrated to the end of the improvement range while discharging, and the end of the improvement area is improved, the discharge of the solidified material from the lower discharge port is stopped, and the solidified material is discharged only from the upper discharge port. The ground improvement method is to lift the stirring shaft while rotating the stirring shaft while stirring and mixing the soil and the solidified material with the stirring blade.
[0006]
In addition, as an apparatus used in the above-mentioned ground improvement method, an upper discharge port and a lower discharge port are respectively provided on upper and lower portions of a stirring blade installed at a tip end of a stirring shaft having a solidified material supply path, and a rod-like shape is provided on an outer periphery of the stirring shaft. Alternatively, plate-like stirring assist members are radially attached at predetermined intervals, in multiple stages up to the upper portion of the stirring shaft, and a disk-shaped stirring assist member for reducing displacement applied to the surrounding ground is attached to the stirring shaft. Is a ground improvement device attached to
[0007]
In addition, the present invention is a ground improvement apparatus in which one or more disk-shaped stirring assist members are provided in addition to the stirring shaft.
[0008]
[Action]
According to the method of the present invention, the agitating shaft penetrates to a predetermined depth in the ground to be improved in the ground, and further, the solidification material is simultaneously discharged from the discharge ports provided at the top and bottom of the agitating blade at the tip of the agitating shaft. The solidified material can be spread sufficiently and the solid material can be improved more reliably because the tip of the nozzle is improved.At the time of pulling up, the discharge from the lower discharge port is stopped by the action of the stop valve or differential pressure valve. The tip can be improved by a mechanism.
[0009]
Further, since the apparatus of the present invention has a configuration in which a rod-shaped or plate-shaped half-shaking auxiliary member is provided in multiple stages up to the upper part of the half-shaft, the ground is loosened, the solidified material spreads well, and mixing unevenness is improved. , The co-rotation phenomenon between the half wing and the soil can be suppressed, and furthermore, the soil is removed and the displacement of the surrounding ground can be suppressed.
In addition, the removal of the soil is facilitated by the disk-shaped stirring assist member.
[0010]
【Example】
An embodiment of the ground improvement method of the present invention will be described below with reference to the drawings.
FIG. 2 shows a ground improvement device according to claim 2 used in the ground improvement method of the present invention. The ground improvement device is connected to a driving device 3 guided by a leader 2 of a base machine 1 so as to be vertically movable and rotatable. An excavating head 6 is provided at the tip of a stirring shaft 5 supported through the extruder 4, a stirring blade 7 is provided above the cutting head 6, and a solidified material supply path of the stirring shaft 5 is provided above and below the stirring blade 7 ( An upper discharge port 8 and a lower discharge port 9 for discharging the solidified material from an unillustrated discharge port are provided, and the solidified material can be discharged from the upper and lower discharge ports 8 and 9 simultaneously or from only one of them.
[0011]
Further, a number of rod-shaped stirring assisting members 10 are attached radially at predetermined intervals to the outer periphery of the stirring shaft 5, and a number of them are attached to the upper part of the shaft of the stirring shaft.
The rod-shaped stirring assisting member 10 may be attached to the stirring shaft 5 in a staggered manner as shown in FIG. 3 (A), or as a disk as shown in FIGS. 3 (B) and 3 (C). One or more stirring assist members 11 are provided.
The sticking position and interval of the rod-like or thin plate-like stirring assisting member 10 and the disk-like stirring assisting member 11 of the stirring shaft 5 are determined by construction conditions such as soil properties.
[0012]
Although the ground improvement apparatus shown in FIGS. 2 and 3 has the stirring shaft 5 as a single shaft, a ground improvement device having two stirring shafts 5 as shown in FIG. 4 may be used.
In this case, the co-rotation preventing plate 13 is attached to the stirring shafts 5 and 5 in a loosely fitted state and connected thereto.
In FIG. 2, reference numeral 12 denotes an intermediate steady rest device.
[0013]
The ground improvement method of the present invention using the ground improvement device of the present invention configured as described above will be described with reference to FIG.
As shown in FIG. 1A, the base machine 1 is moved on the ground A to be improved, the stirring shaft 5 is set at the improved position, and the driving device 3 is driven in this state, and the stirring shaft 5 is moved to the improved range. The intrusion H is performed while discharging the soil B to a predetermined depth (FIG. 1 (b)).
[0014]
Further, after the stirring shaft 5 has penetrated H to a predetermined depth in the improvement range, the solidification material is simultaneously discharged from the discharge ports 8 and 9 provided in the upper and lower portions of the stirring blade by the solidification material injection / pump (not shown). Rotation penetrates I deeper than the range to form a tip-end hardened body D at the tip C of the improved range (FIGS. 1 (c) and (d)).
[0015]
Next, a stop valve (not shown) or a differential pressure valve (not shown) is operated to prevent the solidified material from being discharged from the lower discharge port 9, and the solidified material is discharged into the soil only from the upper discharge port 8. The stirring shaft 5 is rotated and pulled up to form an improved hardened pile K (FIG. 1 (d)).
[0016]
By repeating the above steps, a cured body is sequentially formed to improve the soft ground.
[0017]
【The invention's effect】
Using the apparatus of the present invention, in the method of the present invention, after the stirring shaft is penetrated to the planned depth of the improvement range, and the solidification material is simultaneously discharged from the solidification material discharge ports provided above and below the stirring blade, the penetration is improved. The tip can also be improved reliably.
That is, the upper and lower discharge ports 8, 9 are provided above and below the stirring blade 7 at the tip end as shown in FIG. 1A, and after penetrating the stirring shaft to the planned depth in the improvement range, Although the solidification material is simultaneously discharged from the solidification material discharge ports 8 and 9 provided above and below the stirring blade and penetrates deeply, the upper discharge flow from the upper solidification material discharge port 8 as shown in FIG. E is discharged in the direction of the stirring blade 7 at the tip C, and the solidified material is uniformly supplied to the tip of the improved range together with the lower discharge flow F from the lower discharge port 9, as shown in FIG. By forming the hardened tip portion D in the improved range tip portion, the strength of the tip portion is also ensured.

[0018]
Also, by protruding the agitating auxiliary member on the agitating shaft, the unevenness of the mixture between the solidified material and the soil is reduced by loosening the ground, the co-rotation phenomenon can be suppressed, and even when penetrating and pulling up Since the earth removal is performed, the displacement of the surrounding ground can be suppressed.
[0019]
Moreover, the method and apparatus of the present invention are constituted by a simple mechanism, and an effective method and apparatus can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a construction procedure of a construction method of the present invention.
FIG. 2 is an overall view of a ground improvement machine equipped with the ground improvement device of the present invention used in the ground improvement method of the present invention.
FIG. 3 is an overall view of the apparatus of the present invention.
FIG. 4 is an enlarged view of a main part having two stirring shafts.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base machine 2 Leader 3 Drive 4 Connecting flange 5 Stirring shaft 6 Drilling head 7 Stirrer blade 8 Upper discharge port 9 Lower discharge port 10 Stirring auxiliary member 11 Disc-shaped stirring auxiliary member 12 Intermediate steady rest device 13 Co-rotation prevention plate A Improvement Expected ground B Discharge C Improvement area Tip D Improved tip hardened body E Upper discharge flow F Lower discharge flow H Penetration I Penetration injection stirring direction J Pulling injection stirring direction K Improved curing pile

Claims (3)

A ground improvement method that improves the ground by stirring and mixing the solidified material discharged from the discharge port at the tip of the stirring shaft and the soil by rotating the stirring shaft equipped with multiple stages of excavation heads and stirring blades at the tip ,
The stirring shaft penetrates to a predetermined depth in the ground to be improved in the ground, and is further deepened from the front end of the improvement range while simultaneously discharging the solidified material from the discharge ports provided at the top and bottom of the stirring blade at the tip of the stirring shaft. After forming the hardened tip part in the tip part of the expected improvement area by penetrating the shaft, stop the discharge of the solidified material from the lower discharge port, and stir the stirring shaft while discharging the solidified material only from the upper discharge port. A ground improvement method characterized in that the agitating shaft is pulled up to form an improved hardened body while rotating and stirring and mixing the soil and the solidified material with the agitating shaft. An apparatus used in the ground improvement method according to claim 1 , wherein an upper discharge port and a lower discharge port are provided on upper and lower portions of a stirring blade installed at a tip end of a stirring shaft having a solidifying material supply passage, and the outer periphery of the stirring shaft is provided. A rod-shaped or plate-shaped stirring assisting member is radially attached at predetermined intervals to the upper portion of the stirring shaft in multiple stages, and a disk-shaped stirring assisting member is provided along with the stirring shaft to reduce displacement applied to the surrounding ground. A ground improvement device characterized by the following. The ground improvement apparatus according to claim 2, wherein one or more disk-shaped stirring assist members are provided in addition to the stirring shaft.

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