JP3697348B2 - Improvement method for soft ground - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a method for improving soft ground by mechanical stirring used in the field of civil engineering and construction.
[0002]
[Prior art]
Conventionally, in the construction of civil engineering and building structures, for the purpose of increasing the ground support capacity, deforming the ground (sinking, swelling, protruding), reducing or eliminating water pressure and water permeability, maintaining and enhancing durability, etc. The soft ground has been improved.
[0003]
Here, the soft ground is not limited to a specific ground, but is determined by the relative nature of the structure to be built and the nature of the ground, so it is not uniquely determined. Generally, it is a generic term for silt or clay with fine soil particles and a large pore ratio, special soil such as peat with extremely high compressibility, and loose sand ground with a high groundwater level that tends to liquefy during an earthquake.
[0004]
When such soft ground is improved, it is important to apply a construction method suitable for the situation at the construction site, and many methods for improving soft ground have been proposed. For example, when improving soft ground under a hard surface layer that does not require improvement, an open-blade mechanical stirring method is applied.
This construction method is a single machine equipped with an agitating shaft and an auger head on the agitation shaft, which enables drilling and agitation of the ground. Discharge and agitation of improved materials such as cement slurry, and soft ground. An improved layer is created by improving the soil as consolidated soil. The process is performed according to the following procedure.
(A) The improvement unnecessary layer on the hard surface is closed with a stirring blade provided on the stirring shaft and drilled with a small diameter.
(B) Drilling with the blade closed to the bottom of the soft ground that needs improvement, opening the blade fully open at the bottom of the soft ground, stirring while discharging the improvement material to the top of the soft ground, and creating an improved body To do.
(C) After constructing the improved body to a predetermined depth of the soft ground that requires improvement, the stirring blade is contracted, the stirring shaft is rotated in the reverse direction, and the stirring shaft is pulled out while stirring.
[0005]
[Problems to be solved by the invention]
However, the conventional open-blade mechanical agitation method fully opens the stirring blade at the lower end of the soft ground that needs to be improved, so if there is an obstacle such as a hard rock in the middle when the soft ground is improved, A large load was applied, and in some cases, the stirring blade could not be driven. In such a case, since the process of drawing out the stirring blade, inserting it into the soft ground again, and repeating the process is repeated, there is a problem that much labor and time must be spent for improving the soft ground.
Further, when the improved diameter of the soft ground is expanded, the drilling machine and the drilling shaft are enlarged accordingly, and the drilling diameter in the surface layer that does not require improvement becomes proportionally larger.
[0006]
This invention is made | formed in view of such a problem, and it aims at providing the mechanical stirring construction method which can reduce excavation and displacement of the surface layer ground which need not be improved, and can complete improvement.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention has the following configuration.
The gist of the invention described in claim 1 is a soft ground improvement method using a drilling / stirring device equipped with a stirring blade capable of excavating and stirring the ground, and the stirring blade is closed to the soft ground requiring improvement. After drilling in the bladed state, from the upper end to the lower end of the soft ground that needs improvement, the stirring blade is opened at a predetermined angle, the excavation step of drilling the ground, and the stirring blade is further opened at a predetermined angle while rotating There exists in the improvement method of the soft ground characterized by alternately repeating the pulling-up process which pulls up and drills.
The gist of the invention described in claim 2 is a soft ground improvement method using a drilling / stirring device equipped with a stirring blade capable of excavating and stirring the ground, and the stirring blade is closed to the soft ground that needs improvement. Drilling in the bladed state, opening the stirring blade at a predetermined angle from the upper end to the lower end of the soft ground that needs improvement, drilling step for drilling the ground, fully opening the stirring blade, and pulling up while rotating The present invention resides in an improved construction method for soft ground, characterized by comprising a pulling-up process for drilling holes.
The gist of the invention described in claim 3 is that, in the excavation step, the ground is improved by rotating the stirring blade while discharging the improvement material into the soft ground. It exists in the improvement method of soft ground.
According to a fourth aspect of the present invention, in the pulling-up step, the ground is improved by rotating the stirring blade while discharging the improving material into the soft ground. It exists in the improved construction method of soft ground described in Crab.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 to 4 are process diagrams showing an improved construction method for soft ground according to an embodiment of the present invention.
First, as shown in FIG. 1, in improving the soft ground 2 that needs to be improved under the improvement unnecessary layer 1, the stirring blade 3 is closed and the improvement unnecessary layer 1 is drilled with a small diameter. The stirring blade 3 has a structure capable of expanding and reducing the diameter by opening and closing. The expansion / contraction diameter structure includes various structures such as a pantograph type, but is not limited to a specific structure.
Next, as shown in FIG. 2, the agitating blade 3 is half-opened while rotating from the upper end of the soft ground 2 requiring improvement to a predetermined depth, and the soft ground 2 is drilled while maintaining the state. While drilling, the improved material such as cement slurry is discharged and stirred for primary stirring (digging process). In this step, drilling is performed with a diameter of about 200 mm to 800 mm.
Next, as shown in FIG. 3, the stirring blade 3 is fully opened while rotating at a predetermined depth of the soft ground 2 that needs to be improved, and the improved material is discharged and stirred while being pulled up to start secondary stirring. Upper process). In this step, drilling with a maximum diameter of about 1200 mm is performed.
Finally, as shown in FIG. 4, the improved body 4 is created up to the upper end of the soft ground 2 that needs to be improved at a predetermined drawing speed while discharging and stirring the improved material.
[0009]
Since the improvement method of the soft ground 2 according to the embodiment of the present invention is performed in the steps as described above, the load applied to the stirring blade during drilling is small, the torque can be reduced, and the influence of obstacles such as rocks This is advantageous in that the soft ground having a large diameter can be improved in a short time.
In addition, by drilling in a half-open state rather than fully open, the load applied to this type of stirring blade during excavation and stirring can be reduced, so there is no need to make the stirring blade body committee and the opening and closing mechanism of this stirring blade robust. The drilling machine and the drilling shaft rod do not become so large, and the drilling diameter in the surface layer that does not require improvement does not become large as in the prior art.
[0010]
In addition, in the said embodiment, although the ground was improved in 2 steps, an excavation process and a pulling-up process, this invention is not limited to it, The improvement process may be 3 steps or more. In that case, the opening angle of the stirring blade can be reduced according to the number of steps.
[0011]
Moreover, although the improvement material was discharged in both the excavation process and the pulling-up process, the present invention is not limited thereto, and the improvement material can be discharged only in the pulling process. In the case where the digging process and the pulling process are repeated a plurality of times, the discharge of the improving material can be repeated only in the final process or only in the predetermined process.
[0012]
Moreover, although the ground improvement method excavated in the substantially vertical direction of this invention was illustrated in FIGS. 1-4, in this invention, it can construct in all directions, such as a horizontal direction and a diagonal direction other than a substantially ceiling direction. This is because the drilling and agitation process in the half-open state is performed before the fully open state, and as a result, the drilling rod has a small diameter, and the drilling machine can be used with a relatively small size.
[0013]
In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a number, position, shape, and the like that are suitable for implementing the present invention. In each figure, the same numerals are given to the same component.
[0014]
Furthermore, in the present invention, depending on the situation of the construction site, in addition to the improved construction method of the soft ground 2 of the present invention, various dehydration methods, various replacement methods, various compaction methods, various consolidation methods, various waterstop methods, etc. It is possible to use one or more of the improved construction methods for soft ground in combination.
[0015]
【The invention's effect】
Since the present embodiment is configured as described above, the following effects can be obtained.
After drilling with the stirring blade in the half-open state, drilling is performed with the stirring blade in the fully open state, so the load on the stirring blade during drilling is small, torque can be reduced, and it is not easily affected by obstacles such as rocks. The effect that the improvement of the soft ground can be completed in the shortest time is achieved.
In addition, when creating an improved diameter of the same size as compared with the conventional method, according to the present invention, the drilling diameter of the improvement unnecessary layer can be reduced, so that excavation / displacement of the surface ground is kept to a minimum. Can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a step of drilling a non-improvement layer according to the present embodiment with a small diameter by closing a stirring blade.
FIG. 2 is a cross-sectional view showing a step of drilling and primary stirring the soft ground according to the present embodiment without fully opening the stirring blades.
FIG. 3 is a cross-sectional view showing a process of fully opening a stirring blade and starting discharge of an improved material at a predetermined depth of a soft ground according to the present embodiment.
FIG. 4 is a cross-sectional view showing a process of creating an improved body by discharging and stirring the improved material according to the present embodiment.
[Explanation of symbols]
1 Improvement unnecessary layer 2 Soft ground 3 Stirring blade 4 Improved body

Claims (4)

An improved construction method for soft ground using a drilling / stirring device equipped with a stirring blade capable of excavating and stirring the ground,
After drilling with the stirring blade closed, until soft ground that needs improvement,
From the upper end to the lower end of the soft ground that needs to be improved, the stirring blade is opened at a predetermined angle, and the excavation process for drilling the ground,
A method for improving soft ground, wherein the agitating blade is further opened at a predetermined angle, and a pulling-up step of drilling and drilling while rotating is alternately repeated. An improved construction method for soft ground using a drilling / stirring device equipped with a stirring blade capable of excavating and stirring the ground,
Drilling with the agitator blade closed until the soft ground needs improvement,
From the upper end to the lower end of the soft ground that needs to be improved, the stirring blade is opened at a predetermined angle, and the excavation process for drilling the ground,
A method for improving soft ground, comprising: a step of lifting the stirring blades fully open and pulling them up while rotating. 3. The soft ground improvement method according to claim 1 or 2, wherein in the excavation step, the ground is improved by rotating a stirring blade while discharging the improvement material into the soft ground. The soft ground improvement method according to any one of claims 1 to 3, wherein, in the pulling up step, the ground is improved by rotating a stirring blade while discharging the improvement material into the soft ground.

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