JPH11269865A - Improvement method for soft ground - Google Patents

Abstract

(57) [Summary] The present invention provides a mechanical stirring method capable of reducing excavation and displacement of a surface layer that does not require improvement, and completing the improvement. SOLUTION: The stirring blade 3 is half-opened to a predetermined depth from the upper end of the soft ground 2 requiring improvement, and the soft ground 2 is bored while maintaining the state. While drilling, an improving material such as cement slurry is discharged and stirred to perform primary stirring (digging process). In this step, the diameter is about 200 mm-8.
Drill at 00 mm. Next, as shown in FIG. 3, the agitating blade 3 is fully opened while rotating at a predetermined depth of the soft ground 2 requiring improvement, and the improving material is discharged and stirred while being lifted to start secondary stirring (pulling). Upper process). In this step, a hole having a maximum diameter of about 1200 mm is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving soft ground by mechanical stirring used in the field of civil engineering and construction.

[0002]

2. Description of the Related Art Conventionally, when constructing civil engineering and building structures, the ground support capacity has been increased, the ground has been deformed (subsidence, swelling, bulging), the hydraulic pressure and water permeability have been reduced or eliminated, and the durability has been maintained. Improvement of soft ground has been carried out for the purpose of improvement.

[0003] Here, the soft ground is not limited to the specific ground, but is determined by the relativity between the structure to be constructed and the properties of the ground. Generally, it is a general term for special soils such as silt and clay, which have a large porosity, and have a large void ratio, peat having extremely high compressibility, and a loose sandy ground with a high groundwater level that is easily liquefied during an earthquake.

[0004] When improving such soft ground, it is important to apply a construction method suitable for the situation of the construction site, and a number of improvement methods for soft ground have been proposed. For example, when improving soft ground under a hard surface layer that does not require improvement, an open-wing mechanical stirring method is applied. With this method, drilling and agitation of the ground are possible with one machine equipped with an open-wing agitator and an auger head on the agitator shaft.
An improved layer is formed by discharging and stirring an improving material such as cement slurry to improve the soft ground as solidified soil. The process is performed in the following procedure. (A) The hard surface layer that is not required to be improved is drilled with a small diameter by closing a stirring blade provided on a stirring shaft. (B) Drill a hole with the blade closed to the lower end of the soft ground requiring improvement, open the blade fully at the lower end of the soft ground, and stir while discharging the improver to the upper end of the soft ground to form an improved body I do. (C) After forming the improved body to a predetermined depth of the soft ground requiring improvement, the stirring blade is contracted, and the stirring shaft is pulled out while rotating the stirring shaft in the reverse direction.

[0005]

However, in the conventional open-wing mechanical stirring method, since the stirring blades are fully opened at the lower end of the soft ground requiring improvement, obstacles such as hard rocks or the like may be interposed when the soft ground is improved. When an object exists, a large load is applied to the stirring blade, and in some cases, the driving of the stirring blade may become impossible. In such a case, there is a problem that a great deal of labor and time must be spent for improving the soft ground because the steps of pulling out the stirring blade, inserting and stirring again into the soft ground are repeated. Further, when the improved diameter of the soft ground is increased, the drilling machine and the drilling shaft become larger accordingly, and the drilling diameter on the surface layer that does not need to be improved becomes proportionally larger.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a mechanical stirring method capable of reducing excavation and displacement of a surface layer that does not require improvement and completing the improvement.

[0007]

In order to solve the above-mentioned problems, the present invention has the following construction. The gist of the invention according to claim 1 is a method of improving soft ground using an excavation / stirring device provided with a stirring blade capable of excavating and stirring the ground, wherein the stirring blade is closed until the soft ground requiring improvement. After drilling in the winged state, from the upper end to the lower end of the soft ground requiring improvement, open the stirring blade at a predetermined angle, a digging step to drill the ground, and further open the stirring blade at a predetermined angle, while rotating An improvement method for soft ground characterized by alternately repeating a pulling process of raising and drilling holes. The gist of the invention according to claim 2 is a method of improving soft ground using an excavation / stirring device provided with a stirring blade capable of excavating and stirring the ground, wherein the stirring blade is closed until the soft ground requiring improvement. From the top to the bottom of the soft ground that needs improvement,
The agitating blade is opened at a predetermined angle, a digging step of drilling the ground, and a lifting step of fully opening the agitating blade, pulling up while rotating, and drilling the ground, comprising: Exist. The gist of the invention according to claim 3 is that, in the excavation step, the ground is improved by rotating a stirring blade while discharging an improving material into the soft ground. It exists in the method of improving soft ground. The gist of the invention described in claim 4 is that, in the lifting step, the ground is improved by rotating a stirring blade while discharging an improving material into the soft ground. It lies in the method of improving soft ground described in Crab.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 are process diagrams showing a method for improving soft ground according to an embodiment of the present invention.
First, as shown in FIG. 1, in improving the soft ground 2 which needs improvement below the improvement unnecessary layer 1, the stirring blade 3 is closed and the improvement unnecessary layer 1 is drilled with a small diameter. This stirring blade 3
Has a structure that can be expanded and contracted by opening and closing. There are various structures such as a pantograph type as the expanding and contracting diameter structure, but it is not limited to a specific structure. Next, as shown in FIG. 2, the stirring 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 bored while maintaining the state. While drilling, an improving material such as cement slurry is discharged and stirred to perform primary stirring (digging process). In this step, drilling is performed at a diameter of about 200 mm to 800 mm. Then, FIG.
As described above, the stirring blade 3 is fully opened while rotating at a predetermined depth of the soft ground 2 requiring improvement, and the improved material is discharged and stirred while being lifted to start secondary stirring (pulling step).
In this step, a hole having a maximum diameter of about 1200 mm is formed. Finally, as shown in FIG. 4, an improved body 4 is formed up to the upper end of the soft ground 2 requiring improvement at a predetermined drawing speed while discharging and stirring the improved material.

The method for improving the soft ground 2 according to the embodiment of the present invention is performed in the above-described steps, so that the load applied to the stirring blade during drilling is small, the torque can be reduced, and obstacles such as rocks can be reduced. It is hardly affected by the above-mentioned effects, and has an effect of improving a large-diameter soft ground in a short time. Also, by drilling in a half-open state instead of fully open, during excavation, the load applied to this type of stirring blade at the time of stirring can be small, so it is not necessary to make the stirring blade body member and the opening and closing mechanism of this stirring blade robust. The drilling machine and the drilling shaft rod are not so large, and the drilling diameter in the surface layer that does not need to be improved does not become large as in the prior art.

In the above-described embodiment, the ground is improved in two steps of the excavating step and the pulling step. However, the present invention is not limited to this. good. In that case, the opening angle of the stirring blade can be reduced according to the number of steps.

Further, the improvement material is discharged in both the excavating step and the lifting step. However, the present invention is not limited to this, and the improvement material can be discharged only in the lifting step. When the excavation step and the pulling step are repeated a plurality of times, the discharge of the improving material can be repeated only in the final step or only in a predetermined step.

Although FIGS. 1 to 4 illustrate the method of improving the ground excavated in a substantially vertical direction according to the present invention, the present invention can be applied to any direction such as a horizontal direction and a diagonal direction other than the substantially ceiling direction. is there. This is due to the fact that the drilling / stirring process in the half-opened state is performed before the fully opened state, so that the drilling rod can have a small diameter, and a relatively small drilling machine can be used.

Further, the number, position, shape, etc. of the above-mentioned constituent members are not limited to the above-mentioned embodiment, but can be set to a suitable number, position, shape, etc. for carrying out the present invention. In the drawings, the same components are denoted by the same reference numerals.

Further, according to the present invention, various dewatering methods, various replacing methods, various compacting methods, various consolidating methods, and various waterproofing methods are used together with the method of improving the soft ground 2 according to the present invention, depending on the construction site. It is possible to use one or two or more of methods for improving soft ground such as a method of construction.

[0015]

The present embodiment is configured as described above, and has the following effects. After drilling with the stirring blade half-open, drilling is performed with the stirring blade fully open, so the load on the stirring blade during drilling is small, torque can be reduced, and it is hard to be affected by obstacles such as rocks This has the effect that the improvement of the soft ground can be completed in the shortest time. In addition, in the case where an improved diameter having the same size is created as compared with the conventional method, according to the present invention, the drilling diameter of the unnecessary layer can be reduced.
Displacement can be kept to a minimum.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a step of drilling a small diameter hole in an unnecessary improvement layer according to the present embodiment 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 blade.

FIG. 3 is a cross-sectional view showing a step of fully opening a stirring blade at a predetermined depth of the soft ground according to the present embodiment and starting discharge of an improving material.

FIG. 4 is a cross-sectional view showing a process of forming an improved body by discharging and stirring the improving material according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Improvement unnecessary layer 2 Soft ground 3 Stirrer blade 4 Improved body

Continued on the front page (72) Inventor Takashi Endo 4-2-35 Kudankita, Chiyoda-ku, Tokyo Light Industry Co., Ltd.

Claims (4)

[Claims] 1. A method of improving soft ground using an excavating / stirring device provided with a stirring blade capable of excavating and stirring the ground, wherein the cutting is performed in a state where the stirring blade is closed to a soft ground requiring improvement. After drilling, the stirring blade is opened at a predetermined angle from the upper end to the lower end of the soft ground requiring improvement, a digging step of drilling the ground, and the stirring blade is further opened at a predetermined angle, pulled up while rotating, and drilled. An improved method of soft ground characterized by alternately repeating the lifting process. 2. A method for improving soft ground using an excavating / stirring device provided with a stirring blade capable of excavating and stirring the ground, wherein the cutting is performed in a state where the stirring blade is closed to the soft ground requiring improvement. Drilling a hole at a predetermined angle from the upper end to the lower end of the soft ground requiring improvement, and excavating the ground; and fully opening the stirring blade and pulling it up while rotating to pull the hole. An improved construction method for soft ground, comprising an upper process. 3. The method for improving soft ground according to claim 1, wherein in the excavation step, the ground is improved by rotating a stirring blade while discharging an improving material into the soft ground. . 4. The soft ground according to claim 1, wherein, in the lifting step, the ground is improved by rotating a stirring blade while discharging an improving material into the soft ground. Ground improvement method.