JPH1161131A - Improving of ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem incapable of permeating and injecting an injecting material into an impermeable ground whose coefficient of permeability is lower than 10<-2> cm/sec, when injecting a suspension type injecting material which has a water/cement ratio of 100-400% and is added with a dispersing agent in an amount of 1-1.3% based on the ultrafine particle cement as an injecting material into ground in improvement of sandy soil and incapable of creating a continuously improved stratum in the case when the ground comprises a laminated stratum composed of an impermeable sandy soil and a sandy soil-clay soil, because usual injection method is carried out by injecting an injecting material under low pressure and by a pitch of 25-100 cm. SOLUTION: An injecting material which has a (water/ultrafine particle cement) ratio of 200-1,500% and contains a dispersing agent in an amount of 1-15% based on the ultrafine particle cement is prepared and the injecting material is jetted to sand soil under high pressure of 100-600 kgf/cm<3> to create a continuous improved stratum comprising a high-pressure jetting improvement area and a permeation improved area. As a result, influence is hardly exerted upon surrounding ground, because pressure is made to escape by permeation of injecting material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention creates an improved ground in which a high-pressure injection-improved area and a permeation-improved area are added by injecting a durable and permeable ultrafine cement injection material into the ground at a high pressure. And improvement of the high-pressure injection method.

[0002]

2. Description of the Related Art Among the improvement methods for soft ground, an injection material used for a high-pressure injection method mainly comprises ordinary cement, blast furnace cement and cement-based solidifying material, and has durability but poor permeability. In addition, the solution type injection material used for the injection method has permeability but has poor durability.

[0003]

In order to solve the problem of permeability described above, it has been proposed to use ultrafine cement as a durable and highly permeable filler. When ultrafine cement is used as an injection material, conventionally, a suspension type injection material obtained by adding a water cement ratio of 100 to 400% and a dispersing agent to the ultrafine particle cement in an amount of 0.1 to 1.3% is used as the ground. However, this injected material could not be injected into the impermeable ground having a water permeability of less than 10 ^-2 cm / sec. The injection method is 25-10
In order to inject the injection material at a low pressure at a pitch of 0 cm,
In the case of alternately-layered soil consisting of impermeable sandy soil and sandy / cohesive soil, it was not possible to construct a continuous improvement.

[0004]

According to the present invention, in order to solve the above-mentioned problems, the water-cement ratio of ultra-fine cement is set to 2 or less.
The injection material is prepared by adding 100 to 1500% of the dispersant to the fine particle cement in an amount of 1 to 15%, and is injected into the sandy soil at a high pressure of 100 to 600 kgf / cm ² to improve the high pressure injection area. This is a ground improvement method that creates a continuous improvement body consisting of a penetration improvement area.

[0005] Further, the ultrafine cement used in the above-mentioned soil improvement method has an average particle size of 4 μm, a maximum particle size of 10 μm, and a residue of 3 μm.
% Or less, and a specific surface area of brane of 7000 to 12000c
m ² / g inorganic compound, and a naphthalene sulfonate-based dispersant used for the injection material.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on the following examples. Example (1) Specifications of ultrafine cement injection material Table 1 shows the characteristics of the ultrafine cement used in the experiment.

[0007]

[Table 1]

Table 2 shows the specifications of the ultrafine cement injection material and the ordinary high-pressure injection injection material used in the experiment.

[0009]

[Table 2]

(2) Characteristics of the ground Table 3 shows the characteristics of the ground used in the experiment. FIG. 1 shows a columnar diagram and a cross section of the improved body.

[0011]

[Table 3]

(3) Specifications of injection material injection Table 4 shows specifications of injection material injection. The location diagram is shown in FIG.

[0013]

[Table 4]

Results of Implementation (1) Infiltration Mechanism The high-pressure injection method is more reliable than the injection method for the finished mold of the improved body. However, it is said that a general single-pipe high-pressure injection method may exert a displacement on the surrounding ground because it does not emit sludge. It is said that this is because when the improvement material is forcibly pressed into the ground, the stress in the ground increases due to an increase in the volume in the ground, and the surrounding ground is pushed. Therefore, in addition to the improved diameter formed by high-pressure injection, using a highly permeable ultrafine cement suspension as the improving material, the improved diameter is expanded by infiltrating the suspension with the pressure confined in the ground. Aim for it. Further, since the pressure is released due to the penetration of the suspension, the influence on the surrounding ground is small.

(2) Injection Time and Improved Diameter The results obtained on the ground shown in Table 3 based on the specifications of the injection material shown in Table 4 are as follows.
As shown in FIG. In the case of the ultrafine particle injection material, the injection time and the improved diameter are in a proportional relationship, and the longer the injection time, the larger the improved diameter. A similar relationship is shown for cement-based solidification materials,
The ultrafine cement injection material shows a larger value.

(3) High-pressure injection improvement area and permeation improvement area FIG. 4 shows the high-pressure injection improvement area and the permeation improvement area. When the injection time is long, the high pressure injection improvement area is 70cm ~ 100c
m, and the permeation improvement area is 30 cm to 50 cm.
The longer the injection time, the larger the high pressure injection improvement area and the larger the permeation improvement area.

[0017]

According to the present invention, as described above, an injection material is prepared by adding a water cement ratio of ultrafine cement of 200 to 1500% and a dispersant by adding 1 to 15% to ultrafine cement. Pressure of 100 to 600 kgf / cm ²
By injecting at a high pressure, a continuous large-diameter improved body composed of a high-pressure injection improving region and a permeation improving region can be formed. In addition, since the pressure is released due to the infiltration of the injection material, the influence on the surrounding ground is small, and the construction can be performed close to the existing structure.

[Brief description of the drawings]

FIG. 1 is a diagram showing a columnar diagram and an improved body forming cross section in an on-site construction experiment for an embodiment of a ground improvement method of the present invention.

FIG. 2 is a position diagram of an on-site construction experiment in an embodiment of the ground improvement method of the present invention.

FIG. 3 is a diagram showing a relationship between an injection amount and an improved diameter in an embodiment of the ground improvement method of the present invention.

FIG. 4 is a diagram showing a high-pressure injection region and a permeation region in an embodiment of the ground improvement method of the present invention.

Continuing on the front page (72) Inventor Soichi Fujii 2-17-4 Yanagibashi, Taito-ku, Tokyo Inside Onoda Chemiko Co., Ltd. (72) Inventor Toshiro Shinkoshi 2-17-4, Yanagibashi, Taito-ku, Tokyo Onoda Chemiko Co., Ltd. (72) Inventor Kimihiko Ichikawa 2-17-4 Yanagibashi, Taito-ku, Tokyo Inside the Onoda Chemiko Co., Ltd. (72) Inventor Noriko Fuchigami 2-17-4 Yanagibashi, Taito-ku, Tokyo Inside the Onoda Chemiko Co., Ltd.

Claims (4)

[Claims] 1. An injectable material obtained by improving a sandy ground by adding a water cement ratio of ultrafine cement to 200 to 1500% and a dispersant in a mass ratio of 1 to 15% to the ultrafine cement. In the ground at a pressure of 100 to 6
A ground improvement method characterized by injection at a high pressure of 00 kgf / cm ² . 2. The improvement of sandy ground, the average particle size of 4
μm, a maximum particle size of 10 μm, a residue of 3% or less, a water cement ratio of ultrafine cement having a Blaine specific surface area of 7000 to 12000 cm ² / g to 200 to 1500%, and a dispersant of 1 to 15 to the ultrafine cement. % Of the injected material is added to the ground at a pressure of 100 to 600 kg.
A ground improvement method characterized by injection at a high pressure of f / cm ² . 3. The soil improvement method according to claim 1, wherein the dispersant is a naphthalene sulfonate-based dispersant. 4. The ground improvement method according to claim 1, wherein the dispersant is a mixture of a naphthalene sulfonate-based material and a retarder for an injection material of ultrafine cement.