JPH09143981A - Deep layer ground processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the effect of processing a deep layer ground using a simple device with a high efficiency. SOLUTION: In either or both of the process of inserting a rotary shaft rotating into the ground and the process of drawing it off, the shaft is sunk or raised bit by bit while the shaft is put in undulate vertical motions by an elevating/sinking device. The undulation should preferably be arranged greater in either of the rising and sinking motions than the other (Figure attached shows the draw-out process, where a>b). It is preferred that inserting process is made continuously while a ground reformer is being fed and that the draw-out process is made with undulation. The elevating/sinking device should favorably be of rack-and-pinion type, with which agitation and mixing are performed with open vanes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process in which, while rotating a rotary shaft, it penetrates to a certain depth in the ground and then withdraws it. The present invention relates to a deep ground treatment method for improving the ground by stirring and mixing the ground improving agent and the ground soil.

[0002]

2. Description of the Related Art Mainly, in order to prevent a so-called co-rotation phenomenon in which soil near a stirring blade rotates together with the stirring blade, it is not possible to vertically move (vibrate) a rotating shaft in a wavy manner with an appropriate amplitude during construction of deep ground treatment. Although it is well known in the art (Actual Kaihei 4-138)
No. 428, Japanese Patent Application Laid-Open No. 5-98631), in this way, the accuracy of agitation and mixing is increased, the average bearing capacity of the treatment section is increased, and the variation of the bearing capacity is reduced, and the treatment effect is improved. This was confirmed by the laboratory experiments recently conducted by the present inventors as described below.

However, in the above-mentioned conventional example, since the means for raising and lowering the rotary shaft and the means for vertically moving the rotary shaft in a wavy manner are used together, there is a problem that the construction apparatus becomes complicated accordingly.

[0004]

SUMMARY OF THE INVENTION The problem to be solved by the present invention, that is, the object of the present invention is to solve the above-mentioned problems of the conventional example, and with a relatively simple device, relatively efficiently,
It is to provide a deep ground treatment method capable of improving the treatment effect.

[0005]

In order to solve the above-mentioned problems, in the deep ground treatment method of the present invention (hereinafter simply referred to as the method of the present invention), a step of penetrating into the ground while rotating a rotary shaft and a withdrawal In either one or both of the steps, construction is performed in which the rotating shaft is moved up and down in a wavy manner by the lifting device and gradually lowered or raised.

In the method of the present invention, when the rotary shaft is moved up and down in a wavy manner in the step of penetrating the rotary shaft, the descending motion of the rotary shaft is made larger than the upward motion, and the rotary shaft is moved up and down in a wavy form in the drawing process of the rotary shaft. When moving, it is preferable in terms of construction efficiency that the moving movement of the rotating shaft is made larger than the moving movement of the rotating shaft.

According to the method of the present invention, in the step of penetrating the rotary shaft, the rotary shaft is continuously penetrated into the ground while supplying a certain amount of the ground improvement agent from the lower end of the rotary shaft to the rotating region of the stirring blade. However, it is advantageous from the standpoint of improving the treatment effect that in the process of pulling out the rotating shaft, the rotating shaft is vertically moved in a wavy manner by the lifting device and gradually raised.

In the construction method of the present invention, it is preferable to use a rack and pinion system as the lifting device for the rotating shaft.
Further, it is preferable to carry out stirring and mixing with a stirring blade provided with an opening where a kneading effect due to passage of soil can be expected.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the deep ground treatment method, a step of penetrating until the lower end of the rotary shaft reaches a certain depth in the ground while rotating the rotary shaft and pulling out the lower end of the rotary shaft until reaching the ground surface. Although there is a process, in the method of the present invention, in one or both of the penetration process and the extraction process of the rotary shaft described above, the rotary shaft is gradually lowered or raised while being vertically moved in a wavy manner by its lifting device. I am trying to do it.

It should be noted that the above-mentioned construction in which the rotary shaft is moved up and down in a wavy manner (hereinafter referred to as "wave construction") may be carried out not in all of the steps but in a part thereof.

FIG. 1 is an explanatory view of a preferred embodiment of the construction method of the present invention. The wavy solid line in the drawing shows the locus of the lower end of the rotary shaft when wave construction is carried out in the drawing process of the rotary shaft. As is apparent, when the ascending / descending motion a is made larger than the descending motion b with the lifting device of the rotating shaft,
The rotation axis gradually rises at the speed shown by the dotted line in the figure.

To improve the accuracy of stirring and mixing, the momentum which is the sum of the ascending motion a and the descending motion b is increased to increase the ascending motion a.
It is better to reduce the finishing height c which is the difference between the lowering movement b and the lowering movement b. However, considering the efficiency of construction, it is preferable to make the vertical movement in small steps. It is appropriate that the finishing height c is 15 cm and the finishing height c is 15 cm, or the ascending movement a is 40 cm and the descending movement b is 20 cm so that the finishing height c is 20 cm.

When performing wave construction in the step of penetrating the rotating shaft, the magnitude relationship between the ascending motion a and the descending motion b is reversed, and the rotating shaft is gradually lowered by the difference.

As a wave construction included in the present invention, a mode in which the ascending motion a and the descending motion b are made equal and these are gradually increased or decreased is conceivable. It is not preferable in terms of construction efficiency.

FIG. 2 shows the variation of the ground bearing strength by the coefficient of variation V of the average ground bearing capacity and the ground bearing strength (the ratio between the standard deviation of the ground bearing capacity and the average ground bearing strength) obtained by the laboratory experiments recently conducted by the present inventors. It is a relational diagram with (coefficient), and in this figure, the higher the vertical axis is and the left is horizontal axis (V is closer to 0), the higher the mixing accuracy is.

2A shows the case where the standard blade (conventional general stirring blade) is normally used, and B shows the case where the standard blade is used for the wave processing. The wave processing improves the stirring and mixing accuracy and the ground treatment effect. It can be seen that it will improve.

The conventional example disclosed in the above-mentioned Japanese Patent Laid-Open No. 5-98631 supplies the ground improving agent in parallel with the vertical movement of the rotary shaft. Since it is difficult to uniformly supply the soil improvement agent to the portion, the effect of reducing V by the wave construction may be reduced.

Therefore, in the step of penetrating the rotary shaft, the rotary shaft is continuously penetrated into the ground while supplying a certain amount of the ground improvement agent from the lower end of the rotary shaft to the rotating region of the stirring blade. It is preferable to perform wave construction in the drawing step.

In FIGS. 3 and 4 showing an example of an apparatus suitable for carrying out the construction method of the present invention, 1 is a construction vehicle, 2 is a leader standing on the front of the construction vehicle 1, and 3 is a leader 2. A rotary shaft support part 4 that moves up and down along a rotary shaft 4 extends downward from the rotary shaft support part 3 via a swivel mechanism, a rotary device 5 rotates the rotary shaft 4, and a horizontal direction 6 is a lower end part of the rotary shaft 4. The reference numeral 7 designates a stirring blade projecting from the above, a reference numeral 7 denotes a ground improving agent discharge nozzle which is opened on the back side of the stirring blade 4, and 8 denotes a co-rotation preventing material attached to the lower end portion of the rotating shaft 4.

In the illustrated apparatus, the lifting device for the rotating shaft 4 is of the rack and pinion type, the leader 2 is provided with a rack, and the rotating shaft supporting portion 3 is provided with a pinion and a hydraulic motor for driving the pinion. The rotating shaft 4 is forcibly moved up and down by rotating the pinion, but the lifting device is not limited to this type.

Further, the stirring blade 6 of the illustrated apparatus is not the above-mentioned standard blade, but is provided with an opening 9 in which a kneading effect due to the passage of soil can be expected (hereinafter referred to as an opening blade). A patent application has been separately filed from the applicant company for a ground mixing and mixing treatment apparatus having an opening blade (see Japanese Patent Application No. 7-257278).

FIG. 2C shows D when normally installed with an opening blade.
2 is a case where wave construction was performed with the opening blades, and it is clear from FIG. 2 that the wave mixing construction with the opening blades significantly improves the accuracy of stirring and mixing, and the ground is remarkably improved.

The opening blades are not limited to those shown in the drawings,
For example, a so-called spectacles type in which the opening is vertically oriented as shown in FIG. 5 is also effective.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a preferred embodiment of a construction method of the present invention.

FIG. 2 is a diagram showing the relationship between the average bearing capacity and the coefficient of variation of bearing capacity, which shows the results of indoor experiments conducted by the present inventors.

FIG. 3 is a side view showing an entire example of an apparatus suitable for carrying out the construction method of the present invention.

FIG. 4 is an enlarged front view of a lower end portion of a rotary shaft in the device shown in FIG.

FIG. 5 is a plan view of a spectacle-type opening blade.

[Explanation of symbols]

a: ascending movement, b: descending movement, c: finishing height, A: standard blade with normal construction, B: standard blade with wave construction,
C: In the case of the normal construction with the opening blade, and in the case of the wave construction with the opening blade, 1: Vehicle for construction, 2: Leader, 3: Rotating shaft support part, 4: Rotating shaft, 5: Rotating device, 6: Stirring blade, 7: Ground improvement agent discharge nozzle, 8: Co-rotation preventing material, 9: Opening.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Kawanabe 5-5-2-2, East Coast North, Chigasaki City, Kanagawa Prefecture (72) Inventor Osamu Ishida 1250-185 Kuno, Sowa-cho, Sarushima-gun, Ibaraki Prefecture

Claims (5)

[Claims] 1. The ground improvement agent and the ground supplied to the rotation region by a stirring blade protruding at the lower end of the rotation shaft in the process of penetrating to a certain depth in the ground while rotating the rotation shaft and then withdrawing the same. In the deep ground treatment method that mixes soil with stirring to improve the ground, it gradually descends or rises while moving the rotary shaft up and down in a wavy manner by either the penetration process or the extraction process of the rotary shaft or both. A deep ground treatment method characterized by carrying out construction. 2. When the rotating shaft is moved up and down in a wavy manner in the step of penetrating the rotating shaft, the descending motion of the rotating shaft is made larger than the ascending motion, and when the rotating shaft is moved up and down in a wavy form in the drawing process of the rotating shaft. The method of claim 1, wherein the ascending movement of the rotary shaft is made larger than the descending movement. 3. In the step of penetrating the rotating shaft, while supplying a certain amount of the ground improvement agent from the lower end of the rotating shaft to the rotating region of the stirring blade,
The deep soil treatment method according to claim 1, wherein the rotary shaft is continuously penetrated into the ground, and in the pulling-out process of the rotary shaft, the rotary shaft is lifted while vertically moving in a wavy manner by its lifting device. 4. The deep ground treatment method according to claim 1, wherein a rack and pinion system is used as a lifting device for the rotating shaft. 5. The deep ground treatment method according to claim 1, wherein the stirring and mixing is carried out by a stirring blade provided with an opening capable of expecting a kneading effect due to the passage of soil.