JPH08134890A - Soil improvement method - Google Patents

Abstract

PURPOSE: To eliminate the clearance between column rows, by outwardly ejecting a solidifying slurry while excavating the space of the first column row formed in advance and widening the excavation area to form the second column row. CONSTITUTION: Columns 11 form a row in a state closely positioned to each other and the distance between two rows is almost equal to the diameter. A second row of columns 13 is formed in the space 12. The excavating shaft 3 is lowered while rotating. A solidifying slurry conducted from a slurry path is ejected from the excavating head 8 to the direction N as shown by the arrow and also from the nozzle of agitation blade 9 in the excavation process of the head 8. The solidifying slurry penetrates in the outside of the excavation wall face 14 and gets solid by the ejection of solidifying slurry from the nozzle of the agitation blade 9 in the rising process of the excavation shaft while adversely rotating after it has reached a specified depth. The columns 13 formed in this way has a larger diameter than the diameter at the excavating position cut by the excavation head 8. By the construction of the columns 13, the space between the columns 11 is occupied by the columns 13 and hence, columns are constructed without space between them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method.

[0002]

2. Description of the Related Art When constructing a structure on soft ground, a cement column is constructed in the ground in order to strengthen the ground. For the construction of this column,
An earth drilling head such as an earth auger is used to excavate the ground, and in the process of excavation, solidifying material slurry (for example, cement milk) is supplied from the tip of the excavating axis to excavate earth and sand and solidifying material slurry. It is common to condense the soil while mixing with a stirring blade installed on the shaft to create a column.

On the other hand, in constructing a column by mixing and stirring the solidifying material slurry and earth and sand in this manner, a solidifying liquid for solidifying the solidifying material slurry in a short time (for example, when the solidifying material slurry is cement milk) , A sodium silicate solution) is used together (hereinafter simply referred to as a two-liquid stirring method). According to this, since the solidifying material slurry can be solidified in a short time to form a column, it has a number of advantages such that construction can be performed on soft ground and the construction effect can be ensured.

By the way, in the case of completely improving this on a flat ground, columns by a two-liquid stirring method may be installed vertically and horizontally, but since this type of column has a columnar shape with a circular cross section, it is adjacent to each other. Gaps are formed between the columns of the book. The existence of this gap causes a decrease in the strength of the ground.

As a method of eliminating the existence of such a gap, it is conceivable that the two-liquid agitation method is used in which the columns are lapped with each other. However, this increases the number of columns to be constructed and increases the construction cost. There are drawbacks.

[0006]

DISCLOSURE OF THE INVENTION According to the present invention, by constructing columns vertically and horizontally on a flat ground by a two-liquid agitation method, when the ground is strengthened, the gaps between the columns are reliably and easily eliminated. The purpose is to let.

[0007]

According to the present invention, a first column of a plurality of rows is constructed by a two-liquid stirring method with a space left, and then the space is provided at the tip of a rotating excavating shaft. Excavation is performed by the excavation head, and the solidifying material slurry is supplied from at least the tip of the excavating shaft in the course of the excavation, and the earth and sand and the solidifying material slurry are stirred by the stirring blades provided on the excavating shaft, and then the excavating shaft rotates. In the process of being pulled up, the solidifying material slurry is sprayed from at least the tip of the stirring blade, and the solidifying material slurry is permeated toward the outer side of the wall surface formed by excavation, whereby the wall surface and the first column It is characterized in that a second column that fills the space between the wall surface and the wall is constructed.

[0008]

The second column is constructed in the space between the first columns, and the diameter of the second column is larger than the diameter of the portion excavated by the excavation head during the process of pulling up the excavation shaft. The solidified material slurry is expanded around the permeation area. This causes the second column to fill the space between the first columns and thus there is no gap between the first columns.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. Figure 6
Shows an example of an excavator used in the present invention, in which a drive mechanism 2 is installed in a reader 1 so as to be movable up and down, and an excavation shaft 3 is rotated by this drive mechanism 2. The excavation shaft 3 is provided with two fluid passages 4, 5 concentrically,
One fluid passage 4 is located at the center of the excavation shaft 3, and the other fluid passage 5 is provided so as to surround the fluid passage 4. The fluid passages 4 and 5 are supplied with grout material necessary for column construction from the grout pumps 6 and 7.

An excavation head 8 is installed at the tip of the excavation shaft 3, and the ground is excavated by the excavation head 8 as the excavation shaft 3 rotates and ascends and descends. The tip of one fluid passage 4 opens at the center of the drilling head 8. At the beginning of excavation, the excavation shaft 3 rotates and descends, and the solidifying material slurry as the grout material is discharged from the grout pump 6 toward the ground excavated from the grout pump 6 through the fluid passage 4. Further, when the excavation shaft 3 is pulled up, the coagulating liquid is discharged from the grout pump 7 through the fluid passage 5.

A plurality of stirring blades 9 are installed on the circumferential side of the excavation shaft 3 so as to extend radially with respect to the excavation shaft 3, and a nozzle 10 is provided at the tip thereof. The tip of the other fluid passage 5 is open to this nozzle 10. Drilling head 8
The excavated soil and the solidified material slurry discharged from the tip of the excavating head 8 are mixed and stirred by the excavating head 8 and the stirring blade 9. .

First, a plurality of columns 11 are installed in parallel by a two-liquid stirring method as shown in FIG. This construction method will be described with reference to FIG. 3, while the solidifying material slurry from the grout pump 6 is discharged from the tip of the excavation head 8 through the fluid passage 4 as shown by an arrow P, and as shown in FIG. 3. Rotate and lower 3. The excavated soil is stirred by the stirring blade 9 together with the solidifying material slurry.

After this excavation reaches a predetermined depth,
(B), the excavation shaft 3 is pulled up while rotating in the reverse direction. During this ascending process, the coagulating liquid is discharged from the grout pump 7 as shown by an arrow M. By this discharge and stirring by the stirring blade 9, the solidifying material slurry discharged previously solidifies in a short time (for example, about 50 seconds to 90 seconds). As a result, the first column 11 is constructed by the soil and the solidifying material slurry that have been previously stirred.

The above-mentioned two-liquid stirring method is a method of filling the solidifying material slurry at the time of excavation and the coagulating liquid at the time of pulling up, but instead of this, it is not filled at the time of excavating, and the solidifying material slurry at the time of pulling up. And the coagulating liquid may be simultaneously filled, or the solidifying material slurry and the coagulating liquid may be simultaneously filled at the time of excavation, and neither may be filled at the time of pulling up, or both at the time of excavating and pulling up. The solidifying material slurry and the coagulating liquid may be simultaneously charged. Further, the solidified material slurry may be filled at the time of excavation, and the solidified material slurry and the solidifying liquid may be simultaneously filled at the time of pulling.
These construction methods are selected appropriately according to the situation of the excavated ground.

As shown in FIG. 4, the columns 11 are formed in rows in a state of being close to each other. The interval between the rows, that is, the parallel interval is an interval corresponding to the diameter of the column 11. Therefore, a space 12 is formed between each row. Column 1
After the solidifying material slurry of No. 1 is solidified, the second column 13 is installed in the space 12. The formation position of this column 13 is
It is a position moved in the column direction by a distance corresponding to the radius of the column 11 column.

Construction of the column 13 will be described with reference to FIG. The soil is excavated by the excavation head 8 while the excavation shaft 3 is also rotated and lowered. Then, as shown in FIG. 1A, during the excavation process, the solidifying material slurry supplied from the fluid passage 4 is discharged from the excavation head 8 as shown by an arrow N. The excavated soil and the solidifying material slurry are stirred by the stirring blade 9. At the same time, the solidifying material slurry is supplied to the nozzle 10 of the stirring blade 9 through the fluid passage 5.
More, for example, at a pressure of about 10 Kg / m ² , it is jetted toward the outer periphery as shown by arrow L.

After the excavation reaches a predetermined depth,
(B), the excavation shaft 3 is pulled up while rotating in the reverse direction. During this ascending process, the solidifying material slurry is discharged from the excavating head 8 in the same manner as during excavation, and at the same time, the solidifying material slurry is stirred through the fluid passage 5 in the same manner as during excavation.
It is ejected from the nozzle 10 toward the outer circumference.

By the injection of the solidifying material slurry from the nozzle 10 of the stirring blade 9 at the time of excavation and pulling up, the solidifying material slurry permeates outward from the excavation wall surface 14 by the excavation head 8. When the permeating solidifying material slurry is solidified, the second column 13 is formed here. The column 13 thus formed has a diameter larger than the diameter of the portion excavated by the excavation head 8. Reference numeral 15 denotes an area of the column expanded by the injection of the solidifying material slurry.

By the construction of this column 13, the column 1
The space between 1 is filled with the column 13, so that the column can be constructed with almost no gap, and a strong improved ground is formed.

As shown in FIG. 2A, during excavation, the solidifying material slurry is discharged only from the excavation nozzle 8, and (b)
The solidifying material slurry may be discharged and injected from both the drilling nozzle 8 and the stirring blade 9 during pulling up as shown in FIG. Although the column 13 is constructed between the rows of the columns 11 in FIG. 4, the column 13 may be constructed between the steel sheet pile 16 and the rows of the columns 11 as shown in FIG.

[0019]

As described above, according to the present invention, by constructing the columns vertically and horizontally on the flat ground by the two-liquid stirring method, it is possible to secure the clearance between the columns of the columns when strengthening the ground. In addition, there is an effect that can be easily solved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining an embodiment method of the present invention.

FIG. 2 is a cross-sectional view for explaining a construction method of another embodiment of the present invention.

FIG. 3 is a sectional view for explaining a two-liquid stirring method.

FIG. 4 is a plan view for explaining an embodiment method of the present invention.

FIG. 5 is a plan view for explaining a construction method of another embodiment of the present invention.

FIG. 6 is a side view for explaining an implementation process of the construction method according to the present invention.

FIG. 7 is a partial sectional view of an excavation shaft.

FIG. 8 is an enlarged sectional view of a part of a stirring blade.

[Explanation of symbols]

 3 Excavation Axis 8 Excavation Head 9 Stirring Blade 11 First Column 12 Space 13 Second Column 14 Excavation Wall Surface 16 Steel Sheet Pile

Claims (1)

[Claims] 1. The ground is excavated by an excavation head provided on an excavating shaft that rotates and moves up and down, and in the course of this excavation, the soil stirred by a stirring blade provided on the excavating shaft is used as a solidifying material slurry from the excavating head. A step of discharging a coagulating liquid for coagulating this to construct a first column in a row, and a ground in a space between the rows of the first column or between the first column and a steel sheet pile. By excavating by the excavating head, discharging the solidifying material slurry from the excavating head to the soil stirred by the stirring blade in the course of this excavation, and spraying the solidifying material slurry from the tip of the stirring blade. , Permeating outward from the wall surface excavated by the excavating head, and thereby the excavation wall surface and the first wall
To fill the space between the wall of the column or the steel sheet pile
Ground improvement method consisting of the process of constructing the column.