JP2000265170A - Method for improving ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a ground by enabling to set a timing for expressing a ground strength depending on requirements by injecting an aqueous solution or a water-based milk of a specific hardener into a specific latent hydraulic area after elapsing a predetermined hours or at the predetermined time and hardening the ground. SOLUTION: A ground is improved by injecting a water-based milk which is a mixture of a latent hydraulic material comprising powdery blast furnace slag and/or powdery Pozolan and water into the ground, preferably agitating and mixing the water-based milk and the ground soil to form a latent hydraulic area in the ground and, after elapsing a predetermined hours or at the predetermined time, injecting an aqueous solution of a hardener for hardening the latent hydraulic material on contacting with the latent hydraulic material or the water- based milk to harden the latent hydraulic area. As the hardener, cement (hydrate), (magnesia) lime, gypsum, an alkali metal hydroxide, an alkaline salt of alkali metals, phosphoric acid (salt), etc., are cited.

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. More specifically, the present invention relates to a method of forming a latent hydraulic region in advance in the ground and hardening it after a desired date and time or at a desired time to improve the ground. .

[0002]

2. Description of the Related Art Conventionally, as a ground improvement method, there is known a method in which an aqueous milk of a solidifying material such as cement is poured into the ground and hydrated and hardened. In addition, in order to prevent collapse of the excavated wall of the ground,
For example, a method is known in which bentonite mud is applied to reinforce the muddy water. In some cases, it is necessary to control the onset time of ground hardening in order to make such ground improvement work proceed smoothly in cooperation with construction work or civil engineering work using the ground. Various means have been developed to do this.

For example, Japanese Unexamined Patent Publication (Kokai) No. 61-212394 discloses that in order to facilitate continuous soil improvement work, granulated blast furnace slag powder, moderately heated Portland cement, and magnesium chloride are used as soil stabilizers. The use of a slow-hardening material is disclosed. Also, Japanese Patent Application Laid-Open No. 9-100
No. 471 discloses that the setting and hardening of cement are promoted,
As a soil-improving injectable material having a low gel-type temperature dependency, easy preparation, and good strength development, CaO-Na
And ₂ O-Al ₂ O ₃ based sintered product, and gypsum, the use of injection material comprising a retarder is disclosed. further,
Japanese Patent Application Laid-Open No. Hei 7-138566 discloses that in order to effectively utilize waste mud and obtain a backfill material for civil engineering, a cement-based solidifying agent is added to waste mud and a setting retarder or dispersant is added to the mixture. A method is disclosed in which a slow-hardening mud material obtained by mixing the materials is backfilled at a backfill site.

In each of the above prior arts, a setting (hardening) retarder is added together with a self-hardening material to a ground improvement injection material to delay the hardening of the self-hardening material. The slow-hardening injection material does not completely stop the progress of the curing reaction of the injection material for a desired period after the injection, and furthermore, the progression speed of the curing reaction depends on the type of the retarder, the amount added, the type of the solidifying material, and the concentration. Since it changes depending on the type of soil, the temperature, and the like, it has been difficult to match the desired strength development time to the desired time in the ground into which the injection material has been injected.
For this reason, in the ground improvement, realization of a method capable of easily matching the strength development time to a desired time has been desired.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a ground improvement method which can easily bring a desired ground improvement effect into conformity with a desired timing.

[0006]

A ground improvement method according to the present invention for solving the above-mentioned problems is characterized in that an aqueous milk prepared by mixing a latent hydraulic material and water is injected into the ground and the ground is improved. An aqueous solution or aqueous milk of a hardening agent that forms a latent hydraulic region therein and contacts and hardens the latent hydraulic material at a desired time or at a desired time is injected into the latent hydraulic region. Then, the latent hydraulic region is cured. In the ground improvement method of the present invention, it is preferable to form the latent hydraulic region by stirring the aqueous milk and the ground soil while injecting the latent hydraulic material-containing aqueous milk into the ground. In the ground improvement method of the present invention, it is preferable that the latent hydraulic material comprises at least one selected from blast furnace slag powder and pozzolan powder. In the soil improvement method of the present invention, the hardening agent is cement, cement hydrate, lime, formic lime, gypsum, alkali metal hydroxide, alkali metal alkali salt, phosphoric acid,
It is preferred to be selected from phosphates.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the soil improvement method of the present invention, a latent hydraulic material contains a mineral component capable of forming a hydrate by a hydration reaction and hardening. A material that does not initiate a hydration reaction even when contacted, and that initiates a hydration reaction and cures when a curing agent is present in the reaction system. Further, in the ground improvement method of the present invention, when the curing agent is brought into contact with the latent water-curable material in the presence of water, the hydration reaction of this material or with this material is started, and this is cured. Means material.

In the method of the present invention, the latent hydraulic material is selected from blast furnace slag powder and pozzolan powder.
It is preferred to use one consisting of more than one species. The pozzolan powder is selected from natural clays such as volcanic ash, clay silicate, diatomaceous earth, bentonite, and kaolin as natural pozzolans, and calcined clays such as calcined kaolin, fly ash (coal ash), and silica fume as artificial pozzolans. Is preferred. Pozzolan powder is a finely powdered siliceous material which does not substantially exhibit hydraulic properties but reacts slowly with calcium hydroxide at room temperature in the presence of water to form a water-insoluble compound and hardens. .

In the method of the present invention, the hardener for the latent hydraulic material may be cement, cement hydrate, lime, formic lime,
It is preferable to use one or more selected from gypsum, alkali metal hydroxide, alkali metal alkali salt, phosphoric acid and phosphate.

When the latent hydraulic material is made of, for example, blast furnace slag powder, the material itself does not hydrate and harden even when it comes into contact with water, but it is used as a hardening agent such as cement. When brought into contact with a material exhibiting alkalinity, the blast furnace slag powder is stimulated by this hardener,
When the hydration reaction is started, hydrated silicate hydrate, lime aluminate hydrate, and the like are generated from the constituent components of the blast furnace slag, so that hydration hardens. Also, the latent hydraulic material is
When they are made of pozzolan powder, they themselves are mainly composed of a silicate component and / or an aluminate component, and do not hydrate and harden even when they come in contact with water. For example, when calcium oxide or phosphoric acid or phosphate is brought into contact, the curing agent reacts with the above-mentioned components of the latent hydraulic material, for example, calcium oxide reacts with the silicic acid component to form calcium silicate hydrate. The hydration and hardening of the hydrated product can be attained by forming the hydrated product or by reacting the phosphoric acid with the aluminate component to form an aluminum phosphate hydrate.

In the ground improvement method of the present invention, an aqueous milk prepared by mixing a latent hydraulic material and water is injected into the ground to form a latent hydraulic region in the ground. This latent hydraulic region is in an uncured state, and hydration hardening does not progress with time. Next, after a lapse of a desired time or at a predetermined time, an aqueous solution of a hardening agent or an aqueous milk is injected into the latent hydraulic region of the ground, and is brought into contact with the latent hydraulic material. The material hydrates and hardens, so the latent hydraulic region of the ground hardens and the ground is improved.

In general, the ground injection of the latent hydraulic material aqueous milk is carried out at a temperature of 5 to 30 ° C. under a pressure of 0 to 6 kgf / cm ² . Grout mixer or agitator,
A grout pump or squeeze pump for pumping milk, an injection pressure, injection amount control and measurement device, a display recording device, and the like are used. In addition, it is preferable that the distribution of the latent hydraulic material in the formed latent hydraulic region is made uniform by stirring and mixing the ground soil and the injected aqueous milk together with the ground injection of the aqueous milk. Further, when the aqueous solution or the aqueous milk of the hardener is injected into the latent hydraulic region, the latent hydraulic material mixed soil in this region and the hardener aqueous milk may be stirred and mixed. For the stirring and mixing, a mechanical auger stirring device or a high-pressure injection device is used.

In the method of the present invention, there is no particular limitation on the injection amount of the latent hydraulic material, but in general, an aqueous milk having a water latent hydraulic material ratio (weight ratio) of 0.33 to 2 of the latent hydraulic material is used. it is preferred to inject at a rate of ground soil m ³ per 100～800Kg. There is no particular limitation on the injection amount of the curing agent, but in general, the ratio of the curing agent to the water curing agent (weight ratio) is 0.
An aqueous solution or an aqueous milk of 33 to 2 is added to the latent hydraulic region in an amount of 5% by weight of the latent hydraulic material injected into the latent hydraulic region.
%, More preferably 10% or more, even more preferably 15 to 40%.

In the method of the present invention, there is no limitation on the time from the injection of the latent hydraulic material aqueous milk to the injection of the hardener aqueous solution or the aqueous milk, and the time can be appropriately set as necessary. It is preferable that it is about 1 to 90 days.

In the method of the present invention, hydration hardening is started by the injection of the hardening agent, and the strength of the ground is developed.
It desired set intensity after ~ 28 days can be achieved, for example, a 20 kgf / cm ^2.

For example, blast furnace slag powder and gypsum are mixed at a weight ratio of 85:15, and the mixture (C) and water (W) are stirred so that the water / mixture ratio W / C becomes 0.6. The aqueous milk was prepared by mixing, and the aqueous milk was injected into the ground at an injection rate of 300 kg / m ³ ,
A day or 14 days later, a hardening agent consisting of ordinary Portland cement is stirred and mixed so that the water / cement ratio W / C becomes 0.6 to prepare an aqueous milk.
When injected into the ground at an injection rate of 50 kg / m ³ ,
Table 1 shows the ground strength at the age of 1 to 28 days.

[0017]

[Table 1]

As is apparent from Table 1, the latent hydraulic material according to the method of the present invention maintains latent hydraulic properties in the ground soil after filling, and exhibits strength (ie, hydration hardening) even at 28 days of age. It is not allowed. However, hydration hardening progresses immediately by the injection of the curing agent, and about 2 hours after the injection of the curing agent.
After a week, a compressive strength of about 20 kg / cm ² can be developed. That is, the time from the injection of the latent hydraulic material to the development of the ground strength can be appropriately set.

Example 1 Aqueous milk having a water-blast furnace slag powder ratio of 0.6 as a potential hydraulic material was injected into the ground in the Ariake district of Tokyo at a rate of 250 kg / m ³ , and then poured. After 3 days, an aqueous milk having a water / cement ratio of ordinary Portland cement of 0.6 as a hardener was injected at an injection rate of 50 kg / m ³ , and 1 day, 3 days, 7 days, 1 day after the injection of the latent hydraulic material.
The unconfined compressive strength (kgf / cm ² ) of the ground after 4 days and 28 days was measured. In Comparative Example 1, an aqueous milk having a water / cement ratio of ordinary Portland cement of 0.6 was injected at an injection rate of 300 kg / m ³ instead of the latent hydraulic material. No hardener was injected. In Comparative Example 2, in place of the ordinary Portland cement used in Comparative Example 1, "Litterlock" (trademark) manufactured by Sumitomo Osaka Cement Co., Ltd. was used as the slow-hardening material, and the same as in Comparative Example 1. The ground was strengthened. Further, in Comparative Example 3, 3% (by weight) of a retarder (trade name: Pozoris No. 89, manufactured by Pozoris Bussan Co., Ltd., composite of modified ribonin and oxycarboxylic acid compound) was added to the ordinary Portland cement of Comparative Example 1 above. ), And an aqueous slurry having a water mixture ratio of 0.6 of this mixture was injected into the ground at an injection amount of 300 kg / m ³ , and the same ground reinforcement as in Comparative Example 1 was performed. The compressive strength of the ground was measured 1, 3, 7, 14, and 28 days after injection of the hydraulic material. Table 2 shows the results.

[0020]

[Table 2]

As is apparent from Table 2, for example, in the case of performing the construction of inserting the H steel material into the ground after the injection of the ordinary portland cement, in the comparative example 1, when the ordinary portland cement was injected into the ground, Since the strength is developed in one day, the H steel material has to be inserted immediately. For example, it was practically impossible to insert the H steel material into this ground at the age of 3 days. In other words, the control of the construction progress became extremely cramped. on the other hand,
In Comparative Examples 2 and 3, when a slow-hardening material or a mixture of ordinary Portland cement and a retarder was used, the development of ground strength was significantly delayed, and even at a material age of 28 days,
There was a disadvantage that the desired strength was not reached. In the examples of the method of the present invention, the strength was developed by injecting the hardener at the age of 3 days, and it was possible to reach around the desired strength at the age of about 14 days. At 28 days of age, the strength reached almost the same as that of Comparative Example 1 using ordinary cement.

Example 2 A fly ash was used in place of the blast furnace slag powder in place of the latent hydraulic material of Example 1, and an aqueous milk having a water fly ash ratio of 0.6 was injected at an injection rate of 250 kg / m ³ , and then After 3 days, a phosphoric acid solution having a P ₂ O ₅ concentration of 30% was injected as a hardening agent at an injection amount of 50 kg / m ³ , and after 1 hour, 3 days, 7 days, 14 days, Twenty-eight days later, the unconfined compressive strength of the ground was measured. Table 3 shows the measurement results.

[0023]

[Table 3]

As is apparent from Table 3, the latent hydraulic material according to the method of the present invention develops strength after injecting the hardener, and has a considerably higher strength at the age of 7 days than when blast furnace slag powder is used. Indicated.

[0025]

According to the method of the present invention, it is possible to set the timing of the development of the ground strength in the ground improvement work as desired, and to increase the strength from the time when the strength is developed.
In a day, the desired set intensity can be sufficiently reached. Therefore, it is possible to appropriately adapt the progress of the ground improvement work and other related works, and the practical utility thereof is extremely high.

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[Procedure amendment]

[Submission date] January 31, 2000 (200.1.3
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006]

A ground improvement method according to the present invention for solving the above-mentioned problems comprises mixing a latent hydraulic material comprising at least one selected from blast furnace slag powder and pozzolan powder with water. The aqueous milk prepared as described above is poured into the ground to form a latent hydraulic region in the ground, and at a desired time, or at a desired time, the latent hydraulic material is brought into contact with and hardened by hardening. An aqueous solution or aqueous milk of the agent is injected into the latent hydraulic region to cure the latent hydraulic region. In the ground improvement method of the present invention, it is preferable to form the latent hydraulic region by stirring the aqueous milk and the ground soil while injecting the latent hydraulic material-containing aqueous milk into the ground. In the soil improvement method of the present invention, the hardening agent is cement, cement hydrate, lime,
It is preferable to be selected from magnesia lime, gypsum, alkali metal hydroxide, alkali metal alkali salt, phosphoric acid and phosphate.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

In the method of the present invention, the latent hydraulic material is selected from blast furnace slag powder and pozzolan powder.
Use those consisting of more than one species. The pozzolan powder is selected from natural clays such as volcanic ash, clay silicate, diatomaceous earth, bentonite, and kaolin as natural pozzolans, and calcined clays such as calcined kaolin, fly ash (coal ash), and silica fume as artificial pozzolans. Is preferred. Pozzolan powder is a finely powdered siliceous material which does not substantially exhibit hydraulic properties but reacts slowly with calcium hydroxide at room temperature in the presence of water to form a water-insoluble compound and hardens. .

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // C09K 103: 00 (72) Inventor Hideo Takahashi 3-23-21 Toyo, Koto-ku, Tokyo F-term in ESTEC Corporation (Reference) 2D040 AB01 AB03 CA01 CA03 CA04 CA05 CA10 CB03 CC02 4H026 CA01 CA02 CA05 CB01 CB02 CB08 CC06

Claims (4)

[Claims] 1. An aqueous milk prepared by mixing a latent hydraulic material and water is poured into the ground to form a latent hydraulic region in the ground, and after a desired period of time, or At a time, an aqueous solution or an aqueous milk of a hardening agent that comes into contact with and hardens the latent hydraulic material is injected into the latent hydraulic region to cure the latent hydraulic region, Improvement method. 2. The aqueous milk containing latent hydraulic material,
The ground improvement method according to claim 1, wherein the aqueous milk and the ground soil are stirred and mixed while being injected into the ground to form the latent hydraulic region. 3. The soil improvement method according to claim 1, wherein the latent hydraulic material comprises at least one selected from blast furnace slag powder and pozzolan powder. 4. The hardening agent is at least one selected from cement, cement hydrate, lime, magnesite lime, gypsum, alkali metal hydroxide, alkali metal alkali salt, phosphoric acid and phosphate. The ground improvement method according to claim 1, comprising: