JP2001323455A - Excavating and agitating device for improving ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excavating and agitating device for improving the ground, enabling enhancement of workability and economy. SOLUTION: The device has a hardener discharge opening 5 at the end of a rotating rod 1; an agitating blade 2 rotating along with the rotating rod 1; a rotation prevention blade 3 located thereabove; and a plurality of agitating blades 4 located further thereabove which rotate along with the rotating rod 1, with all of these members being arranged in a predetermined spaced relationship. The interval W1 between the agitating blade 2 and the rotation prevention blade 3 is smaller than the height or width H of the rotation prevention blade 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement for forming an improved body (soil cement column) in the ground by mechanically stirring a solidified material such as cement milk and excavated soil for ground improvement. It relates to a drilling and stirring device.

[0002]

2. Description of the Related Art Heretofore, as an example of this type of ground improvement stirrer, as shown in FIG. 7, an excavating wing 31 which rotates together with the rotating rod 30 at the tip end of a vertically disposed rotating rod 30 is solidified. A plurality of stirring blades 34 which rotate together with the rotating rod 30 and the excavating blade 31 above the counter-rotating blades 33 at predetermined intervals. What is comprised by every other is generally known.

According to this device, the rotating rod 3 is driven by the driving force.
The excavation is performed by the rotation of the excavation wing 31 together with 0. At the same time as the excavation, the solidified material is discharged from the discharge port 32 into the excavated soil, and the stirring blades 34 and the rotary rod 30 are discharged together.
The rotation causes the solidified material and the excavated soil to be agitated, thereby forming a columnar improved body (soil cement column).
In addition, the underground continuous wall and the like can be easily formed by repeatedly performing the improved body while partially overlapping the improved body.

In this type of apparatus, the distance W between the excavation wing 31 and the anti-rotational wing 33 is generally larger than the height H of the anti-rotational wing 33. Even if it was done, it was possible to improve the ground to a predetermined depth without any problem in most of the ground.

[0005]

However, in the conventional apparatus, when the lowermost layer to be ground-improved is made of highly viscous soil such as tuffy clay, the lowermost layer is improved especially in the improved ground. In many cases, large clay lumps are mixed in the soil cement, and thus the strength of the improved soil cement may not be sufficiently exhibited.

In order to solve this problem, it has been necessary to repeatedly raise and lower the apparatus (rotating rod 30) or to agitate while supplying a large amount of solidified material, which is extremely poor in workability and economic efficiency. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a ground improvement excavating and stirring apparatus which can improve workability and economy.

[0008]

According to a first aspect of the present invention, there is provided an excavating and stirring apparatus for improving a ground according to the present invention. The excavation wing that rotates with the rotating rod, the co-rotation preventing wing is provided on the upper side, and a plurality of agitating wings that rotate with the rotating rod are further protruded above the wing wing at predetermined intervals. The distance from the wing is made smaller than the height and width of the anti-corotating wing.

According to a second aspect of the present invention, in the excavation and stirring apparatus for improving the ground according to the first aspect, anti-corotating wings whose both ends are connected to each other protrude below and above the stirring wing, respectively. The distance between the anti-corotating wing and the excavation wing is made smaller than the height and width of the anti-corotating wing.

According to a third aspect, in the excavation and stirring device for improving the ground according to the first or second aspect, the discharge port of the solidified material is opened obliquely to the direction in which the excavation diameter projects.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a digging and stirring device for ground improvement according to the present invention. In the drawing, a digging wing 2 is protruded from a lower end portion of a rotating rod 1 rotated by a driving force. Immediately above, a co-rotation prevention blade 3 and, further above, a plurality of stirring blades 4 protrude at predetermined intervals in the axial direction of the rotating rod 1. Further, a discharge port 5 of the solidified material is formed at the lower end of the rotating rod 1 so as to open obliquely to the projecting direction of the excavating wing 2.

The excavating wing 2 and the stirring wing 4 are integrally provided on the side of the rotating rod 1 so as to rotate together with the rotating rod 1. Further, the co-rotation prevention wing 3 has a diameter larger than the digging diameter of the digging wing 2 and is loosely fitted to the rotating rod 1 via the boss, so that it does not rotate together with the rotating rod 1 and is substantially in the soil. It is protruded so as to be stationary. By adopting a structure other than this structure, the co-rotation prevention blade 3 may be configured to rotate in the reverse direction.

As a method for projecting the anti-corotating wing 3 so as to be substantially stationary in the soil without rotating, for example, as shown in FIG. A method may be used in which a through hole 3a (usually referred to as a "boss") having an inner diameter slightly larger than the outer diameter is formed, and the rotating rod 1 is passed through the through hole 3a.

Incidentally, a flange is fixed to the rotating rod 1 in order to prevent the corotation preventing blade 3 from moving in the vertical direction.

In order to achieve such a configuration, the co-rotation preventing blade 3 is formed, for example, by forming two plate-like members 3c having a semicircular concave portion 3b at the center, and forming a through hole 3a by facing both concave portions 3b. Tie to form a plurality of connecting bolts 6
It is formed in such a manner as to be connected with each other.

In particular, the excavation wing 2 and the anti-corotation wing 3 are each arranged so that the distance W ₁ between the digging wing 2 and the anti-corotation wing 3 is smaller than the height H of the anti-corotation wing 3. It is provided on the rotating rod 1.

In this case, for example, the distance W ₁ between the excavation wing 2 and the anti-rotational wing 3 is 1/1 / H of the height H of the anti-rotational wing 3.
When the excavation wing 2 and the co-rotation prevention wing 3 are protrudingly provided on the side of the rotating rod 1 so as to be about 2 or less, the clay mass is finely pulverized to form a uniform soil cement and the strength is improved. Become uniform.

Also, the co-rotation prevention blade and the excavation wing 2 are arranged so that the distance W ₁ between the excavation blade 2 and the co-rotation prevention blade 3 is about 1/3 or less of the height H of the co-rotation prevention blade 3. When the wings 3 are protruded from the side of the rotating rod 1, the clay mass is further finely crushed and the strength of the soil cement becomes uniform, which is most preferable. However, W ₁ / H is reduced to about 1/10 or less. That is, when the co-rotation prevention blade 3 is tilted by the clearance within the boss, the counter-rotation prevention blade 3 comes into contact with or is locked by the excavation blade 2 and the co-rotation prevention blade 3 rotates integrally with the excavation blade 2. Difficult.

In addition to the anti-corotating wing 3 shown in FIG. 1, an anti-corotating wing may be further provided on the upper portion. Also,
The solidified material discharge port 5 may be oriented in a direction perpendicular to the excavating wing 2 as in the prior art, but as shown in FIG.
When it is oblique, the mixing degree of the soil cement is further improved and the strength becomes uniform.

FIG. 2 shows another example of the excavating and stirring apparatus for improving the ground according to the present invention. In particular, a co-rotation preventing blade 3 is provided on the upper side of the excavating blade 2 in a two-stage manner with a stirring blade 4 interposed therebetween. Has been established. The upper and lower two-stage counter-rotating blades 3 are connected to each other by connecting blades 7 at both ends.

Further, a plurality of stirring blades 4 are provided at predetermined intervals above the co-rotation preventing blades 3 on the upper side. The other configuration is substantially the same as the device described with reference to FIG.

As described above, the two-stage anti-rotational wings 3 are connected to each other by the connecting wings 7, so that the portion of the anti-rotational wings 3 with the rotating rod 1 (the penetration through which the rotating rod 1 penetrates) is provided. Even if the inner portion of the hole 3a is worn, the anti-corotating wing 3 is prevented from rattling or swaying up and down during construction, or the anti-corotating wing 3 is connected in two stages. Therefore, the angle of inclination of the co-rotation prevention blade 3 with respect to the clearance in the boss is limited, so that a problem such as collision with the stirring blade 4 or the excavation blade 2 does not occur. Therefore it is possible to further reduce the distance W _1.

Further, by reducing as much as possible each interval W _3, W ₄ also between the upper and lower co-rotation preventing wing 3 and between the agitating blades 4, the degree of mixing by agitation of the solidifying material and soil excavated And the strength of the soil cement can be made uniform.

Further, when the thickness of the upper portion of the excavation wing 2 is reduced and the length of the excavation claw 2a is lengthened by the reduced thickness, the position of the lowermost portion of the excavation claw 2a is unchanged and the position of the excavation claw 2a is not changed. Cement milk and soil are more uniformly stirred and mixed.

By reducing the distance W ₅ (W _{2 in} the example of FIG. 1) between the anti-corotating blade 3 and the stirring blade 4 above it, the excavated soil and the solidified material tend to be stirred more uniformly. There is.

Embodiment 1 FIG. Next, in order to confirm the specific effects of the present invention, the present invention will be described based on the test execution performed.

First, the height H of the co-rotation prevention blade 3 is set to 220 mm, the interval W ₁ between the excavation blade 2 and the co-rotation prevention blade 3 is set to 70 mm using the excavation and stirring device for ground improvement shown in FIG. The distance W ₂ between the anti-rotation blade 3 and the stirring blade 4 above it is 65 m.
m, and the excavation and agitation diameter D of the agitation wing 2 and the agitation wing 4 were set to 1200 mm, respectively, using a device having a tuffy clay layer at 3.5 to 5 m below the ground,
The ground was improved from the ground surface to 4.5 m below the ground, and three ground improvement bodies (soil cement columns) were constructed.

The solidified material used was cement milk having a water / solidified material ratio of 60%. The rotary rod 1 was rotated while discharging the cement milk from the solidified material discharge port 5 to remove the excavated soil. Cement milk was stirred and mixed to obtain soil cement.

A sample was taken out by coring from the ground improvement body thus formed, and the strength was measured at each depth. There was no variation in strength at any depth.
The same compressive strength was shown between the ground improvement bodies performed at several places.

On the other hand, ground improvement was performed on the same ground as in the previous embodiment using the same solidifying material by using a conventional apparatus. The result is that the depth of 4m from the basement 4m
There was a portion where the strength was reduced in the 5 m tuffy clay layer, and the compressive strength of the improved body at the portion was varied.

Embodiment 2 FIG. Next, shown in FIG. 2, the upper and lower co-rotation preventing wing 3 of the height width H respectively 220 mm, the distance W ₁ of the drilling blade 2 and the co-rotation preventing wing 3 of the immediately above 6
0 mm, the interval W _3, W ₄ each 65mm between the upper and lower co-rotation preventing wing 3 and between the agitating blades 4, further spacing W ₅ of the co-rotation preventing wing 3 of the upper agitating blade 4 of the immediately above 90
mm, and the excavating blade 2 and the stirring blade 4 were set to have an excavating diameter / stirring diameter D of 1500 mm, respectively. The ground was improved to 4.5 m. Three ground improvement bodies were constructed.

The solidified material used was cement milk having a water / solidified material ratio of 60%. The rotating rod 1 was rotated while discharging the cement milk from the solidified material discharge port 5 to remove the excavated soil. Cement milk was stirred and mixed to obtain soil cement.

In the ground improvement body thus constructed,
Before the soil cement is hardened, the electrical resistivity of the soil cement is measured every 10 cm depth at three places (parts marked with a circle in FIG. 4) at a position 1/4 of the diameter of the improved body from the center of the ground improvement body. It was measured.

The measurement of the specific resistance includes a specific resistance measurement cone provided with two current electrodes and two potential electrodes, a cable connected to each electrode of the specific resistance measurement cone, a depth, a potential amount, and a current value. The measurement was performed by using a measuring device composed of a recording device capable of recording the data, and penetrating a resistivity measuring cone into a depth to be measured. Note that this measurement
This is based on the Japan Geotechnical Society standard JGS 1121-1995.

FIG. 5 shows the measurement results of the specific resistance. The specific resistance at a position of 0.5 m to 4.5 m from the ground surface is uniform, indicating that a uniform soil cement is formed over the entire length.

For comparison, the same device is used, and the height H of the upper and lower anti-rotational wings 3 is 220 mm, respectively, and the distance W ₁ between the excavation wing 2 and the immediately above (lower step) anti-rotational wings 3. The distances W _3, W ₄ between the upper and lower co-rotation preventing blades 3 and the stirring blades 4 therebetween, and the distance W ₅ between the upper counter-rotation preventing blades 3 and the stirring blade 4 immediately above the upper side are 235 mm, respectively. Also, the excavation / agitation diameter D of the excavation blade 2 and the stirring blade 4 is set to 1
The ground improvement was performed in the same ground from the ground surface to 4.5 m underground using an excavator set at 500 mm. In addition, the discharge port 5 of the solidified material faces in a direction perpendicular to the excavation wing 2. FIG. 6 shows the measurement results of the specific resistance of this comparative example. There is a point where the specific resistance varies at a position of 3.5 m to 4.5 m from the ground surface and shows a large value.

This means that in these places, FIG.
In the three places at half of the diameter of the improved body indicated by ○,
This indicates that the soil cement is in an uneven state, that is, the solidified material and the excavated soil (original ground) are not sufficiently stirred.

As a precautionary measure, a test sample was taken from this improved product, and the strength was measured. The compressive strength of the test sample at a position where the specific resistance varied had a low value.

As can be seen from the measurement results of the specific resistance,
It is clear that a uniform ground improvement body can be formed by the apparatus of the embodiment. Further, for confirmation, in each of Examples and Comparative Examples, two other ground improvement bodies were formed and the specific resistance was measured. The same tendency was observed.

[0040]

The present invention has been described above. In particular, since the interval between the excavation wing and the co-rotation prevention wing above it is made smaller than the height and width of the co-rotation prevention wing, the apparatus (rotating rod) is used. Without repeatedly raising and lowering or supplying a large amount of solidified material, it is possible to create a uniform improved body near the deepest part of the improved body, and to create an improved body with uniform compressive strength, thus greatly improving workability and economy. Improvement can be achieved.

When the outlet of the solidified material is formed obliquely to the excavation wing, the strength of the improved body becomes more uniform.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a ground improvement excavating and stirring apparatus according to the present invention.

FIG. 2 is a front view showing another example of the excavation and stirring device for ground improvement according to the present invention.

FIG. 3 is a perspective view showing an example of a corotation prevention wing.

FIG. 4 is a plan view showing measurement points of specific resistance.

FIG. 5 is a diagram showing measurement results of specific resistance.

FIG. 6 is a diagram showing measurement results of specific resistance.

FIG. 7 is a front view showing an example of a conventional excavation and stirring device for ground improvement.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating rod 2 Excavation wing 3 Co-rotation prevention wing 3a Through hole 3b Depression 3c Plate 4 Stirring wing 5 Solidification material discharge port 6 Connecting bolt

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Atsushi Murayama 6-13-7 Akasaka, Minato-ku, Tokyo F-term in Tenox Co., Ltd. (reference) 2D040 AA01 AB05 BA08 CA01 EA18

Claims (3)

[Claims] 1. A discharge port of a solidified material and an excavating wing rotating with the rotating rod at the tip end of the rotating rod, a co-rotation preventing wing on the upper side thereof, and a plurality of stirring blades rotating with the rotating rod above the wing wings. At the predetermined intervals, wherein the interval between the excavating wing and the co-rotating wing is smaller than the height and width of the co-rotating wing. apparatus. 2. An anti-corotating blade having a counter-rotating blade at both ends connected to each other on a lower side and an upper side of a stirring blade, and adjusting an interval between the lower counter-rotating anti-blading blade and the excavating blade. The excavation and stirring device for ground improvement according to claim 1, wherein the height is smaller than the height width. 3. A discharge port of the solidified material is opened obliquely to a projecting direction of the excavating wing.
Or the excavation and stirring device for ground improvement according to 2.