JPH06158642A - Method for improving soft ground - Google Patents

Abstract

PURPOSE:To prevent ground volume from increasing by injecting ground hardening material at a ground depth by an amount which is varied depending on the ground strength at that depth, then agitating and mixing the material with soil, and removing the soil by an amount equal to the amount of injection of the material at that depth. CONSTITUTION:A rotating shaft 1, having a screw 2 inserted into its pipe 3 while projecting by a predetermined length from the lower end of the pipe 3, is rotated to take ground soil into the pipe 3 by means of the screw 2. The ground soil taken in is compressed by air fed through an air feed pipe 4 and lifted inside the pipe 3. The amount of ground soil taken into the pipe 3 is varied by varying the number of revolutions of the rotating shaft 1. Next, an earth discharging device is combined to a ground agitating and mixing treatment device, with the end of the screw 2 located above an agitating blade provided between adjacent rotating shafts 1. Detection is carried out continuously using a ground strength detector and the amount Q1 of injection of ground hardening material is made larger at a depth where the ground strength S is small than at a depth where the ground strength is great, and at each depth initial ground soil is removed by a amount Q2 equal to the amount Q1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft ground improvement method for hardening soft ground by stirring and mixing ground hardening materials (cement, cement milk, etc.).

[0002]

[Object of the Invention] One problem in hardening treatment of soft ground by stirring and mixing of ground hardening material is that, depending on the properties of the original ground, a large amount of ground hardening material can reach up to several 10% by volume ratio to ground soil. The mixture may cause the ground to rise or the ground to spread laterally and adversely affect existing surrounding structures.

The object of the present invention is to improve the strength of a soft ground whose strength is not constant in the depth direction of the ground to a uniform strength by stirring and mixing the ground hardening material, and at the same time, to solve the above problems. It is to provide a reasonable soft ground improvement method.

[0004]

The composition of the present invention is characterized in that in a soft ground improvement method in which a soft ground is hardened by stirring and mixing the ground hardening material, the amount changed at each ground depth according to the ground strength at that depth. The point is that the ground hardening material is added and stirred and mixed, and at the same time, the amount of ground soil corresponding to the amount of the ground hardening material added is removed.

In order to carry out the present invention, for example, when the rotary shaft having a stirring blade projecting from the lower end penetrates, the ground strength is continuously detected by an appropriate instrument attached to the lower end of the rotary shaft. The amount of ground hardening material input and the amount of ground soil removal at each depth are determined, and when the rotary shaft is pulled out,
At each depth, a predetermined amount of ground soil may be removed and a predetermined amount of ground hardening material may be stirred and mixed.

[0006]

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, A is an area for ground improvement by the present invention, Z is ground depth, S is ground strength,
Q ₁ represents the amount of ground hardening material input, and Q ₂ represents the amount of ground soil removed. In the present invention, as is clear from FIG. The amount of hardened material input Q ₁ is increased so that the improved strength becomes uniform, and the amount of soil (Q ₂ ) corresponding to the amount of ground hardened material input Q ₁ (Q ₂ ) is eliminated at each depth. By doing so, the increase of the ground volume due to the mixing of the ground hardening material is prevented.

As a device for carrying out the present invention, a conventionally known ground agitation mixing treatment device for agitating and mixing the ground soil and the ground solidifying material is shown in FIG. 2 with agitation blades protruding from the lower end of the rotary shaft. A combination of soil removal devices is possible.

In FIG. 2, 1 is a rotary shaft, 2 is a rotary shaft 1.
A screw for discharging earth attached to the outer periphery of the tip end of the pipe, 3 is a pipe, and 4 is an air feeding pipe opening to the lower end of the pipe 3. In the illustrated soil discharging device, the screw is installed in the pipe 3 as shown in the drawing. 2 rotates the rotary shaft 1 that is inserted in a state in which 2 projects from the lower end of the pipe 3 by a predetermined length,
The ground soil is taken into the pipe 3, and the taken-in ground soil is urged by the air sent through the air feeding pipe 4 to raise the inside of the pipe 3, and the amount of the ground soil taken into the pipe 3, That is, the amount of soil removed can be changed by changing the number of rotations of the rotary shaft 1.

In the conventional well-known ground stirring and mixing treatment apparatus in which rotating shafts with stirring blades are arranged in parallel, the tip of the screw 2 is located at a position above the stirring blades between the adjacent rotating shafts. By combining the shown soil discharging devices, it is possible to continuously discharge soil in an amount corresponding to the input amount of the ground hardening material at each depth of the ground before the stirring and mixing process when the rotary shaft is pulled out.

In the case of carrying out the present invention, naturally, it is necessary to detect the ground strength at each ground depth prior to the stirring and mixing process. For example, the tip end of the reciprocating shaft with stirring blades can be appropriately used. The ground strength detector is installed to continuously detect the ground strength at each depth when the rotary shaft penetrates into the ground, and calculate the required input amount of ground hardening material and the required soil discharge amount at each depth. Just keep it.

[0011]

EFFECTS OF THE INVENTION The method for improving soft ground of the present invention is as described above. Therefore, the soft ground whose strength is not constant in the depth direction of the ground can be improved to uniform strength by stirring and mixing the ground hardening material. It is possible to reliably prevent the adverse effect that the ground volume increases due to the mixing of the ground hardening material.

[Brief description of drawings]

FIG. 1 is a basic explanatory diagram of the present invention.

FIG. 2 is an example of an earth discharging device in the device for carrying out the present invention.

[Explanation of symbols]

A: area, Z: Ground depth, S: ground strength, _{Q 1:} input amount of ground hardener, _{Q 2:} elimination of the ground soil, 1: rotary shaft,
2: Screw, 3: Pipe, 4: Air supply pipe.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuyuki Washizuka No. 203-326, 6-3, Sumikawa, Minami-ku, Sapporo-shi, Hokkaido (Room 808, Sumikawa housing complex No. 6, Building 72) 2 at Komagane 1419 (72) Inventor Masanori Matsushita 2-333 Harayama, Urawa-shi, Saitama (72) Inventor Kazuma Misaka 444-81 Wakaguri, Ami-machi, Inashiki-gun, Ibaraki

Claims (1)

[Claims] 1. In a soft ground improvement method in which soft ground is hardened by stirring and mixing the ground hardener, at a depth of each ground, a quantity of the ground hardener changed according to the ground strength at that depth is charged and stirred. A soft ground improvement method characterized by performing mixing and removing the ground soil in an amount corresponding to the amount of ground hardening material input at that depth.