JP2004156381A - Ground improvement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily improve a soft ground to a hard ground. <P>SOLUTION: A preparatory hole having a specified depth is excavated on the ground face where ground improvement is executed and granular aggregate is put into the formed preparatory hole. While an implement having a hard chip is pressed and rotated to crush the charged aggregate, the crushed aggregate is pressed into the wall face of the preparatory hole to improve the ground. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ground improvement method that can easily improve a soft ground to a hard ground.
[0002]
[Prior art]
In Japanese Patent Application Laid-Open Nos. 2000-1850, 2001-59221 and 2001-182058, the present applicant discloses an anchor (underground) suitable for supporting a branch line of a utility pole such as a distribution line or a telephone line. Anka) is proposed. This anchor is formed by intermittently providing a spiral drilling blade intermittently on the tip side of a cast iron shaft rod (supporting rod) buried underground.
[0003]
Further, the present applicant has proposed an anchor in which a utility pole can be easily erected in Japanese Patent Application No. 2002-146034. In this anchor, a hole of a predetermined depth is dug in the ground on which the telephone pole is erected, an anchor similar to that described above is buried at the bottom of the hole, and a tubular body is placed on top of the anchor. A utility pole is inserted into the body to erect the utility pole.
[0004]
The anchor according to the above proposal is selected in size according to the nature of the ground on which the pole is installed, and the burial depth is determined so that the branch line can obtain a predetermined tension, or stabilize the pole. To support them. For this reason, in order to obtain data for determining the type of anchor to be used and the burial depth, the present applicant disclosed in Japanese Patent Application No. 2000-23876 an N value which is an index indicating the degree of softness of the ground. An N-value measuring tool that can be easily measured and has a rod-like overall shape has been proposed. The N value is determined from the resistance of the ground generated when a hollow measuring instrument (sampler) having an outer diameter of 5.1 cm, an inner diameter of 3.5 cm, and a length of 81.0 cm is driven into the ground as shown in JIS A1219. It is obtained from the number of hits N required for the above-mentioned measuring tool to drop a hammer having a mass of 63.5 kg (about 622.3N) freely from a height of 75 cm and to drive the measuring tool into 30 cm. is there.
[0005]
[Problems to be solved by the invention]
As described above, the anchor according to the above proposal investigates the ground in which the anchor body is buried in advance, and determines the type and burial depth of the anchor body. However, depending on the ground, the N value is too small, that is, In some cases, a large anchor body was required, or the burial depth had to be considerably increased.
[0006]
Therefore, an object of the present invention is to provide a ground improvement method that can easily improve the ground to be hard when the ground is soft.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the ground improvement method according to the present invention, according to the first aspect of the present invention, digs a front hole having a predetermined depth in the ground on which ground improvement is performed, and forms a granular hole in the dug front hole. The aggregate is inserted, and the inserted aggregate is crushed by rotating while pressing a tool having a carbide tip at the tip, and the crushed aggregate is pressed into the wall surface of the front hole. It is characterized by improving the ground.
The ground improvement method according to claim 2 of the present invention is characterized in that the insertion of the aggregate into the front hole is performed in a divided manner, and the aggregate is crushed and pressed using a tool for each insertion. .
The ground improvement method according to claim 3 of the present invention is characterized in that the aggregate is coke.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A to 1E are process diagrams showing a ground improvement method according to one embodiment. Hereinafter, description will be made in accordance with the order of steps.
[0009]
Digging the front hole (prepared hole) (see Fig. 1 (a))
A drilling tool A is placed on the ground G where the ground improvement is performed (used in the same meaning as the ground. Sometimes it is called underground. Therefore, the ground or the ground may be expressed by G). The front hole (prepared hole) H is dug to a predetermined depth, that is, a predetermined depth of the underground G where the ground improvement is required. This drilling tool A is the same as the anchor body proposed by the present applicant in Japanese Patent Application Laid-Open Nos. 2000-1850, 2001-59221, 2001-182058 and the like. The tool will be described as an anchor body A.
[0010]
The anchor body A is made of cast iron, and a plurality of (four in the illustrated example) spiral excavating blades a2, a2... Are integrally formed at a predetermined interval on a rod-shaped shaft rod (supporting rod) a1. Because it has the feature that it can be easily buried in any depth of the underground G using the rotating part of the well-known excavator used when erecting the utility pole, and at any depth There is a feature that if the rotation is stopped when it is buried in the hole, the hole corresponding to the diameter of the anchor main body A can be easily dug when pulled up as it is. The excavating blades a2, a2,... Are formed such that the diameter thereof becomes smaller toward the tip (the lower end in FIG. 1).
[0011]
In order to dig a front hole at a predetermined depth in the underground G using the anchor body A, an auxiliary tool (fitting pipe) is inserted into a prism portion a3 provided at the top of the anchor body A (this auxiliary tool is This is described in detail in Japanese Patent Application Laid-Open No. 2001-271345 according to the application.) M is fitted, and the auxiliary tool M is rotated by a rotating portion of a not-shown boring truck (not shown).
[0012]
Aggregate insertion (see Fig. 1 (b))
Coke C is inserted into the front hole dug using the anchor body A as a predetermined amount (at least an amount that can cover the tool B described later) as granular aggregate. The aggregate to be inserted may be, for example, a material obtained by crushing rubble or concrete waste material in addition to coke C, and the size may be about the size of an adult fist. When the coke C is used as an aggregate, the ground resistance can be reduced when the anchor body A is used as a ground member. Further, the coke C may be impregnated with an additive such as lime, alumina oxide and gypsum to further reduce the ground resistance.
[0013]
Crushing and press-fitting of aggregate (see Fig. 1 (c))
The coke C inserted into the front hole is crushed by the tool B, and the crushed aggregate pieces are pressed into the wall surface of the front hole H. The tool B is proposed by the present applicant in Japanese Patent Application No. 2002-18420, and has carbide tips b2, b2 at the tip of the rod-shaped body b1 and the lower part of the upper brim. When crushing and press-fitting coke (aggregate) C using the tool B, first, the above-mentioned auxiliary tool (fitting pipe) M is provided at the top of the tool B instead of the anchor body A, and the prism portion b3 is provided. It is fitted in. Then, when the tool B is rotated while the auxiliary tool M is rotated while being pressed by a rotating part of a not-shown digging pole wheel, the coke C is crushed, and a part of the crushed coke C is It is press-fitted into the surrounding underground G and formed into a large solid mass at the lower part of the front hole H (see FIG. 1 (d)).
[0014]
After the crushing and press-fitting of the coke C by the tool B is completed, a predetermined amount of coke C is inserted into the front hole H again, and the crushing and press-fitting of the coke C by the tool B are performed again. That is, the steps of FIGS. 1B to 1D are repeated. The coke C can be inserted up to the top of the front hole H, and then crushing and press-fitting using the tool B can be performed. However, the coke C is divided and inserted, and the crushing using the tool B is performed every time the coke C is inserted. When the press-fitting operation is performed, the operation can be performed more efficiently.
[0015]
Completion of improved ground (see Fig. 1 (e))
When the above steps (b) to (d) are repeated up to the front hole H, the soft ground G is improved to the hard ground by the coke C. When the ground on the side surface of the ground G on which the above-described ground improvement method was performed was excavated and observed, one thick compacted columnar body was buried deep in the ground, as if it were a hard pile. In the ground G.
[0016]
Therefore, if the anchor is buried in the ground whose ground has been improved, the tension of the branch line can be sufficiently obtained, or when the utility pole is erected on the anchor, the utility pole can be stabilized. . Furthermore, when a building is erected on the improved ground instead of the above-described anchoring, the same effect as when a pile is driven into the ground can be obtained, and the building can be stabilized.
[0017]
【The invention's effect】
The ground improvement method according to claim 1 of the present invention digs a front hole having a predetermined depth in the ground where the ground improvement is performed, inserts a granular aggregate into the dug front hole, and inserts the inserted bone. Rotate while pressing a tool with a carbide tip at the tip to break the aggregate, and press the crushed aggregate into the wall of the front hole to improve the ground, so soft ground It can be easily improved to hard ground.
In the ground improvement method according to the second aspect of the present invention, the insertion of the aggregate into the front hole is performed in a divided manner, and the crushing and press-fitting of the aggregate using a tool are performed each time the insertion is performed. Can be done easily.
In the ground improvement method according to the third aspect of the present invention, since the aggregate is made of coke, the ground resistance can be reduced when the anchor body is used as the ground member.
[Brief description of the drawings]
FIG. 1 is a process chart showing a ground improvement method according to the present invention.
[Explanation of symbols]
A anchor body (drilling tool)
H Front hole (prepared hole)
B Tool C Coke (Aggregate)

Claims (3)

Digging a front hole of a predetermined depth in the ground where soil improvement is performed, inserting granular aggregate into the dug front hole, and pressing the tool having a carbide tip at the tip of the inserted aggregate A ground improvement method comprising rotating the aggregate to crush the aggregate, and pressing the crushed aggregate into the wall surface of the front hole to improve the ground. 2. The ground improvement method according to claim 1, wherein the insertion of the aggregate into the front hole is performed in a divided manner, and the aggregate is crushed and press-fitted using a tool for each insertion. . The ground improvement method according to claim 1 or 2, wherein the aggregate is coke.

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