JPH07197442A - Soil improvement method - Google Patents

Abstract

PURPOSE:To prevent the surrounding structures and the soil from shifting due to compressed air, by exhausting the compressed air in the ground to the ground surface through the hollow part of a pipe buried in the ground as an exhaust way. CONSTITUTION:A plurality of shorter pipes 2 than soil improving piled body 1 to be constructed are buried at every specified distance by a driving machine to make a division, in a surrounding area B close to an existing structure A. The pipes 2 are stuffed with a granular filler 6 and pierced holes 4 are bored at the body 3. Improving materials for forming the piling body are pressed in the ground B by a piling machine or the like with casing or the like and discharged into the ground by the compressed air to form the piling body 1, at a specified position in the division in which the pipes 2 are buried. After the piling body has been formed in a division, the pipe 2 previously buried is pulled out and then the pipe 2 is buried in the next division and the same piling body 1 is formed in this division.

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 for improving the ground without giving displacement to existing structures and ground around the ground during the ground improvement work carried out by a powder injection stirring method or a quick lime pile method.

[0002]

2. Description of the Related Art Generally, ground improvement work is carried out by a ground improvement method using compressed air such as a powder injection stirring method and a quicklime pile method. Since this improved method injects the improved material into the ground, there is a problem that displacement due to air pressure occurs as well as displacement of surrounding existing structures and ground due to increased volume.

[0003]

In order to solve this problem, conventionally, a method has been adopted in which a stupid hole, that is, a vertical hole is excavated in the vicinity of an existing structure or the surrounding ground, and this is exhausted to the ground as an exhaust path. ing. In addition, a soil stabilizing solution may be filled in the holes in order to stabilize the hole walls of the vertical holes.

However, in this case, depending on the ground, the vertical holes do not stand on their own, the wall of the holes collapses, and the exhaust passage is blocked, so that sufficient exhaust cannot be performed.

Further, filling the hole with a stabilizing solution to stabilize the hole wall also blocks the exhaust passage, and the displacement due to the increase in volume can be absorbed, but the displacement due to compressed air cannot be prevented. Further, when exhausting air through the vertical hole as an exhaust passage, exhaust may occur suddenly at once, which is dangerous.

[0006]

The present invention has been made to solve the above-mentioned problems, and prior to the formation of piles of the improved material, a large number of through holes are formed near the existing structure and the surrounding ground. A plurality of short, rigid pipes pierced in the trunk are embedded at a prescribed interval to form a section, and the improvement material for pile body formation is press-fitted into the prescribed ground in the section and compressed. By forming a pile body in the ground, then pull out the short pipe body from the ground, embed the pulled pipe body in the next place, to form a pile body sequentially by repeating the same work, According to the ground improvement method for improving the ground, the short pipe is buried and then filled with a granular material such as crushed stone, or the pipe filled with the granular material is buried before being buried.

[0007]

The improved material is discharged into the ground by the compressed air of the press-fitting machine (not shown) to form piles. At that time, the compressed air causes strain in the ground, and as the compressed air rises in the ground, the amount of strain increases and the amount of displacement increases. However, the compressed air is collected in the pipe body through a through hole formed in the body peripheral surface of the pipe body that is buried before the pile body is formed, and is exhausted to the ground by using the hollow portion as an exhaust passage.

Further, if the tubular body is filled with a granular material such as crushed stone, the exhaust is performed by using the gap between the particles as the exhaust passage, and the exhaust passage is dispersed, so that the exhaust can be performed more favorably. Further, since the pipe body is rigid, the pipe body is not deformed by earth pressure or the like, and the exhaust passage is not blocked.

[0009]

EXAMPLE An example of the ground improvement method of the present invention will be described with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing an implementation state of the construction method of the present invention, FIG. 2 is a perspective view showing an example of a short tubular body used in the construction method of the present invention, and FIG. 3 is a short scale used in the construction method of the present invention. It is a perspective view which shows the other example of another tubular body. In FIG. 1, prior to forming a group of ground improvement piles 1 on the pile 1 of the surrounding ground B adjacent to the existing structure A, the height of the pile 1 (for example, 10 to 15 m) to be formed A plurality of pipes 2 having a shorter rigidity (preferably 3 to 4 m) than that are buried in the ground at a predetermined interval by a driving machine (not shown) or a press-fitting machine (not shown) to form one section. .

The short tubular body 2 has a structure in which a small through hole 4 is formed on the entire surface of the body portion 3 as shown in FIG. 2, and if necessary, a spiral collar body is formed on the body portion as shown in FIG. 5 is provided. The hollow portion of the short tube body 2 may be filled with a granular material such as crushed stone in advance after the burying or before the burying. The diameter of the pipe body and the interval of driving will be changed appropriately depending on the ground conditions and the position of existing structures. Further, it is not necessary to fill the tubular body with the granular material.

As described above, an improved material for forming a pile body is placed at a predetermined position in a compartment formed by embedding a large number of short pipe bodies 2 by a pile driving machine (not shown) or the like by using a casing or the like. It is pressed into the ground and discharged into the ground by compressed air to form the pile body 1.
After the pile body of one section is formed, the pipe body 2 buried previously is pulled out by a pulling machine (not shown), the next compartment is formed by burying the pipe body 2, and the pile body is formed in the compartment as described above. 1 is formed. By repeating these operations, piles are sequentially formed and the work of forming piles in all sections is completed.

[0012]

Since the present invention has the above-mentioned structure,
The compressed air in the ground can be efficiently exhausted to the ground by the through holes 4 of the pipe body 1 and the granular packing, and the displacement of the surrounding structure and the ground due to the compressed air can be prevented.

Further, since the pipe body used is short, it has an advantage that it is easy to handle and can be used repeatedly, and it is a very effective ground improvement method.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an implementation situation of a ground improvement method of the present invention.

FIG. 2 is a perspective view showing an example of a short tubular body used in the construction method of the present invention.

FIG. 3 is a perspective view showing another example of a short tubular body used in the construction method of the present invention.

[Explanation of symbols]

 1 Pile body 2 Tubular body 3 Body part 4 Through hole 5 Spiral 6 Granular packing A Existing structure B Ground

Claims (2)

[Claims] 1. A ground improvement method for forming a pile of soil improvement material in the ground by using compressed air to improve the ground, and a large number of small through holes are formed in the trunk in the surrounding ground near the existing structure. An improved material for forming a pile body in the ground at a predetermined position in a compartment formed by embedding a plurality of pipe bodies that are shorter than the punched rigid pile body at a predetermined interval and embedding the short pipe bodies. Press-fit,
A pile is formed in the ground by compressed air, then the short pipe is pulled out from the ground, the pulled pipe is embedded in the next place, and the same work as above is repeated to form a pile. Ground improvement method characterized by improving the ground. 2. A ground improvement method, characterized in that the hollow portion of the buried short pipe according to claim 1 is filled with granular material such as crushed stone.