JPH10102476A - Hardener slurry injection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection method wherein hardener slurry, which can achieve improved hardening characteristics and durability for the ground having high natural water content or the ground containing organic acids, without producing bleeding, is injected, and in which there is no need to treat sludge liquid. SOLUTION: Hardener slurry 8 containing colloidal silica and cement solidification agent, as components, is sprayed against the ground by means of a high pressure jet stream to form a solidified body 7. The slurry 8 is prepared by a method wherein a first mixed liquid is prepared by mixing colloidal silica and water at a weight ratio of 1:3-8 and a second mixed liquid is prepared by mixing cement solidification agent and water at a weight ratio of 1:1-4 and the first mixed liquid and second mixed liquid are mixed by either a 1, 5 shot or 2 shot method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to strengthening of soft ground,
The present invention relates to a soil improvement method for stopping water, and more particularly to a hardening material slurry injection method suitable for soil having a high natural water content, soft ground containing humus, and the like.

[0002]

2. Description of the Related Art Conventionally, a method of injecting a slurry containing a hardening material has been performed for the purpose of temporarily or permanently strengthening the ground and stopping water, but in recent years, the method of strengthening the ground of existing structures and preventing liquefaction has been performed. Particular attention has been paid to this as a means.

As the existing hardening material slurry in such an injection method, water glass, cement slurry represented by JIS standards, or cement-based solidified material slurry has been mainly used. However, these materials have a problem that a solid-liquid separation phenomenon, so-called breathing, occurs in the ground. When the breathing occurs, the position of the solidified material of the injected material may be lower than the planned position after consolidation of the injected material injected into the ground, or the ground at the upper end of the consolidated material may collapse after the escape of breathing water, etc. There was a problem. Therefore, measures such as addition of an admixture have been taken to prevent bleeding. At the time of construction, it was necessary to select a material to be added to the hardener slurry according to the construction situation and each soil condition.

Further, the conventional cement slurry has a problem in treating construction sludge because the amount of discharged sludge is large.
Also, there was concern about alkali elution into the soil.

Further, it is known that when the conventional cement slurry is applied to humus soil in particular, the solidification effect of the cement slurry is impaired. For example, when Portland cement is used for humus soil, the organic acid contained in the soil is adsorbed by the cement mineral, which often inhibits the hydration reaction and lowers the strength or does not harden.

[0006] On the other hand, some curing materials made of colloidal silica have already been proposed. Colloidal silica is characterized in that it does not react with organic acids. In addition to colloidal silica, for example, a method using slaked lime or cement (JP-A-59-66482), a method using an alkaline earth metal salt such as magnesium sulfamate (JP-A-63-168485), chloride A method using an alkali metal salt such as sodium or sodium hydrogen sulfate (JP-A-59-152985) and a method using a trivalent metal salt such as an aluminum salt (JP-A-59-152).
No. 984).

[0007] As the injection method for soft ground, there are known methods such as high-pressure injection of hardener slurry alone, high-pressure injection of a mixture of hardener slurry and high-pressure air, or high-pressure injection of a mixture of hardener slurry, high-pressure air and water. Have been. Various publications are disclosed in Japanese Patent Publication No. 55-35531, Japanese Patent Application No. 4-254954, and Japanese Patent Application Laid-Open No. 57-164186. In these injection methods, there is a problem that a large amount of muddy liquid is generated on site.

[0008] At present, an injection method using a hardening material slurry that can prevent breathing and can be effectively applied to humus soil and hardly generates a muddy liquid has been proposed yet.

[0009]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an injection method for injecting an effective hardening material slurry into soft ground. In particular, an object of the present invention is to inject a hardening material slurry capable of obtaining excellent hardening ability and durability without causing bleeding, for example, on a ground having a high natural water content or a humus, that is, a ground containing an organic acid. It is to provide an injection method. further,
SUMMARY OF THE INVENTION An object of the present invention is to provide an injection method that does not require treatment of sludge.

[0010]

In order to achieve the above object, a first embodiment of a method for injecting a hardening material slurry according to the present invention is to provide a hardening material slurry containing colloidal silica and cement-based solidifying material as components. This is a method of forming a consolidated body by injecting it into the ground with a jet.

According to a second aspect of the present invention, in the first aspect, the hardener slurry further contains a gel time regulator.

According to a third aspect of the present invention, in the first aspect, the hardening material slurry to be sprayed on the ground has a weight ratio of the colloidal silica to water of 1: 3 to 8.
And a second liquid mixture having a weight ratio of the cement-based solidifying material to water of 1: 1 to 4 was prepared. Thereafter, the first mixed liquid was prepared. It is formed by mixing the liquid and the second mixed liquid by either 1.5 shot or 2 shot method.

According to a fourth aspect of the present invention, in the third aspect, the hardening material slurry to be sprayed on the ground has a weight ratio of SiO ² in the colloidal silica to the cement-based solidifying material of 0.1. -1: 1.

A fifth aspect of the present invention is the method according to the third or fourth aspect, wherein a gel time regulator is mixed with at least one of the first liquid mixture and the second liquid mixture.

A sixth aspect of the present invention is the method according to any one of the above aspects, wherein when the hardener slurry is jetted by a high-pressure jet, the hardener slurry is jetted together with air and / or water.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The hardener slurry used in the injection method according to the present invention basically contains at least colloidal silica and a cement-based solidifying material as components.
To date, hardener slurries based on a combination of colloidal silica and a cement-based solidifying agent have not been known.

The colloidal silica used in the present invention is obtained by removing Na ₂ O from water glass using water glass as a raw material, and is produced by ion exchange, peptization, acid neutralization, electrodialysis, or the like. You. Examples of this production method are disclosed in JP-A-52-33899, JP-A-1-317115, U.S. Pat. Nos. 2,577,484, 3,711,419, 2,572,578, and 3,668,088. There is.

Other methods for producing colloidal silica include JP-B-46-7367 and US Patent No. 3650.
There is a method by oxidation of metallic silicon described in each publication of No. 977, etc., or a method of dispersing fine silica powder in water described in each publication of JP-A-62-212716 and U.S. Pat. Colloidal silica obtained by the production method can also be used in the present invention.

As the characteristics of colloidal silica, those having a large particle diameter have a low gel strength, so that the average particle diameter is 3%.
A small particle grade colloidal silica having an average particle diameter of 3 to 15 nm is particularly preferable because the gel strength is particularly high.

By using the above-mentioned colloidal silica and a cement-based solidifying material in combination, an optimum hardening material can be obtained. The cement-based solidifying material is of a type different from Portland cement and mixed cement of the JIS standard. Usually, cement is made of Portland cement and JIS standard cement in which admixtures such as blast furnace slag and fly ash are mixed at a predetermined ratio, based on Portland cement as a base, and special cements other than JIS standard such as colloid cement and ultra-rapid hardening cement. It is roughly divided.
The cement-based solidifying material belongs to a special cement, and is a material to which an active ingredient is added in accordance with the purpose such as reinforcement of a specific component according to JIS standards, adjustment of particle size, or soil properties.

The cement-based solidifying material used in the present invention contains a larger amount of sulfur trioxide (SO ₃ ) than ordinary Portland cement or blast furnace cement B. S
O ₃ is contained in the form of gypsum (CaSO ₄ .0.5H ₂ O) or gypsum (CaSO ₄ .2H ₂ O). When the hardening material slurry containing such a cement-based solidifying material is applied to the ground containing an organic acid, the above-mentioned inhibition of the hydration reaction does not occur. The gypsum component absorbs a large amount of water to lower the water content of the soil, and ettringite (3CaO.Al ₂ O _3.
By producing a large amount of 3CaSO ₄ .32H ₂ O), the cement can be easily joined and the reaction with the organic acid can be avoided. Therefore, an increase in strength is achieved without inhibiting the hydration reaction. In addition, the strength of the solidified body by the hardening material slurry increases when the gypsum component content of the cement-based solidified material is 5 to 10%, and particularly when the content is 5%, the strength becomes maximum. If it is 10% or more, it decreases. In addition, the effect of increasing strength can be obtained also by the fact that ettringite takes in a large amount of water as bound water and the formation of calcium silicate hydrate.

The hardener slurry used in the present invention basically contains the above-mentioned two components, ie, colloidal silica and a cement-based solidifying material, and is preferably further formed by appropriate mixing with water. This hardener slurry is characterized by extremely high fluidity.

In forming the hardener slurry used in the present invention, preferably, first, two mixed liquids are prepared. First
The mixed solution of the above has a weight ratio of colloidal silica to water of 1: 3.
~ 8. The second mixed solution is prepared so that the weight ratio between the cement-based solidifying material and water is 1: 1 to 4. Thereafter, the first mixed liquid and the second mixed liquid are mixed, for example, with 1.5 shots (two liquids, one system) or two shots (two liquids, two liquids).
The curing agent slurry is formed by mixing in the injection / injection process using a method such as (system). More preferably,
SiO in colloidal silica constituting hardener slurry
The weight ratio of ₂ to the cement-based solidification material is adjusted to be 0.1 to 1: 1.

It is also preferable to mix a gel time regulator with at least one of the first liquid mixture and the second liquid mixture. In the hardener slurry according to the present invention, the gel time, that is, the solidification time, can be adjusted in the range of 2 to 60 minutes. Therefore, the setting time can be shortened, and hardener slurry and wastewater hardly flow out. In addition, the amount of discharged sludge is an amount that can be condensed on site.
In addition, the alkali metal salt contained in the gel time regulator also acts as a hydration accelerator for the cement-based solidifying material.

FIG. 1 is a diagram showing an example of an embodiment of a hardening material slurry injection method according to the present invention. In this injection method, an injection pipe having an injection mechanism is used. The injection tube may be any one of a single tube, a multiple tube, and a plurality of tubes, and may be a tube having an arbitrary cross-sectional shape. (A) shows the installation state of the ground improvement device 3 at the start of construction and a drilling step (water injection) using the rod 2. (B) shows a state where the drilling has been completed after reaching the final depth 6. Thereafter, as shown in (C), while rotating the rod 2, the hardener slurry 8 is ejected by a high-pressure jet from a discharge hole at the tip thereof, and the rod 2 is pulled up. As the injection method, for example, 1.5 shots or 2 shots are used. In this process, the ground compact 7 is formed. The rod 2 is pulled up to the upper limit of the construction area to terminate the injection. The injection amount of the high-pressure jet is, for example, 30 to 300 l / min. (D) shows the formation state of the columnar ground compact 7 formed after the completion of the injection of the hardener slurry. For the rod 2, the drilling rod and the injection rod may be dedicated rods, respectively, and may be replaced after drilling.

As another example of the embodiment, a triple pipe structure capable of transporting and ejecting three kinds of liquids is provided in the injection rod. The triple tube is provided with a triple nozzle at the tip of the rod, so that three types of liquids can be ejected concentrically and simultaneously. Using such an injection rod having a triple tube and triple nozzle structure, colloidal silica, cement-based solidifying material, and water may be separately pumped through respective passages and mixed with each other during injection by high-pressure injection. .

In the above method, when the hardener slurry is jetted by the high-pressure jet, it is also effective to jet the hardener slurry together with air and / or water. Also,
Since the hardener slurry used in the present invention has a high fluidity, the ground compact can be appropriately arranged in the target ground or in the vicinity of the target structure.

Table 1 shows some examples of the hardener slurry used in the present invention, and shows the test results on these properties. It should be noted that the examples shown do not limit the invention. The compressive strength was measured after preparing a sand gel and curing with moisture.

[0029]

[Table 1]

[0030]

The hardening material slurry injection method according to the present invention is performed using a hardening material slurry composed of colloidal silica and a cement-based solidifying material. This hardener slurry has extremely high fluidity during construction and can be pumped by a liquid transfer device. It can be filled into voids of any shape or mixed by liquefying the ground with a high-pressure jet. It is. Thereby, the consolidation effect of the ground consolidation obtained after the construction was able to be significantly improved.

The pouring method according to the present invention realizes prevention of bleeding of the compacted body, reduction of the muddy liquid and consolidation on site without selecting the soil quality. In addition, it can be applied to the ground having a high natural water content, the spring ground, and the ground under high pressure, and also exhibits excellent hardening ability, that is, durability, especially to humus ground containing organic acids. . In addition, the injection method according to the present invention can also form a ground compact around or immediately below an existing structure.

In addition, the method for injecting a hardening material slurry according to the present invention has high practicability without concern about pollution problems.

[Brief description of the drawings]

FIG. 1A shows the state of the apparatus at the start of construction and at the time of drilling,
(B) is the drilling state to the final depth, (C) is the rod pulling up to the upper limit of the construction area and the injection state of the hardener slurry,
(D) is a figure which shows the state of the columnar ground compact which hardening material slurry injection completed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Swivel 2 Rod body 3 Ground improvement device 4 Rotation of rod body 5 Water injection 6 Final depth 7 Ground consolidated body 8 Hardened material slurry 9 Peripheral ground

Claims (6)

[Claims] 1. A method for injecting a hardening material slurry, comprising injecting a hardening material slurry containing colloidal silica and a cement-based solidifying material as components into the ground by a high-pressure jet to form a consolidated body. 2. The method of claim 1, wherein the hardener slurry further includes a gel time regulator. 3. The method according to claim 2, wherein the hardening material slurry injected onto the ground has a weight ratio of the colloidal silica to water of 1: 3.
A first liquid mixture having a composition of from 1 to 8 was prepared, and a weight ratio of the cement-based solidifying material and water was adjusted to 1: 1 to 4 in a second liquid mixture.
The mixture is prepared by mixing the first mixture and the second mixture by either one of 1.5 shots or 2 shots. 2. The method for injecting a hardener slurry according to item 1. 4. The method according to claim 1, wherein the hardening material slurry to be sprayed on the ground is formed such that the weight ratio of SiO ₂ in the colloidal silica to the cement-based solidifying material is 0.1 to 1: 1. The method for injecting a hardener slurry according to claim 3. 5. The injection method according to claim 3, wherein at least one of the first mixture and the second mixture is mixed with a gel time regulator. 6. The hardening material slurry injection method according to claim 1, wherein when the hardening material slurry is jetted by a high-pressure jet, the hardening material slurry is jetted together with air and / or water. .