JPS62199684A - Soil stabilization works - Google Patents

Abstract

PURPOSE:To obtain a ground outstanding in waterstop capability with readuced syrenesis, by injection into soil an aqueous mixture comprising sodium silicate glyoxal, water-soluble aluminum salt and water-soluble organic acid, inorganic acid and acidic inorganic salt. CONSTITUTION:Soil stabilization is accomplished by injecting into the soil an aqueous mixture comprising (A) sodium silicate, (B) glyoxal, (C) water-soluble aluminum salt (pref. aluminum sulfate, aluminum chloride, potassium alum or sodium alum), and (D) at least one kind of compound selected from (i) water- soluble organic acids (pref. malonic acid, glutaric acid, succinic acid, tartaric acid, citric acid, or acetic acid), (ii) water-soluble inorganic acids (pref. sulfuric acid, hydrochloric acid, phosphoric acid or boric acid) and (iii) water-soluble acidic inorganic salts (pref. sodium dihydrogenborate, sodium dihydrogenphosphate or sodium hydrogensulfate).

Description

[Detailed description of the invention] 3. VI Nari IW (Industrial Application Field) The present invention is a soil stabilization method in which a sodium silicate (water glass) grouting agent is injected into the soil and hardened by gelation. Concerning soil stabilization methods that can reduce soil quality.

(Prior Art) A method of stabilizing soil quality by gelling a grouting agent containing sodium silicate as a main ingredient is widely used.

For grouting agents whose main ingredient is sodium silicate.

There are suspension types based on sodium silicate cement and solution types based on sodium silicate water-soluble hardeners. In particular, solution-type grouting chemicals are widely used to stabilize soil quality because they have a low viscosity and can widely penetrate even fine-grained soil. Solution-type grouting agents include inorganic grouting agents that use inorganic acids or inorganic salts as water-soluble hardening agents, and organic grouting agents that use organic acid esters, organic acid amides, aldehyde compounds, etc. as water-soluble hardening agents. be. However, when using inorganic grouting agents, the compressive strength of the soil after stabilization treatment is not sufficient when the gelation time is adjusted to be long.

Examples of organic grouting agents include agents containing an alkali metal salt of silicic acid and an aldehyde compound (Japanese Patent Publication No. 40
-20055).

A drug containing sodium or potassium silicate, a water-soluble aliphatic aldehyde, and a water-soluble inorganic salt (disclosed in Japanese Patent Publication No. 44-19221).

There are drugs containing water glass, glyoxal and sodium bicarbonate (disclosed in JP-A-52-84811). No matter which drug is used.

The gelation time can be easily adjusted, and the soil after stabilization has a constant compressive strength. However, due to the syneresis phenomenon, a large amount of syneresis water is generated from the gel, which tends to reduce the water-stopping properties of the soil.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and its purpose is to develop a soil stabilization method with good water-stopping properties since the amount of syneresis water is extremely small. It is about providing. Another object of the present invention is to provide a soil stabilization method with excellent compressive strength.

Still another object of the present invention is to provide a soil stabilization method that allows easy adjustment of gelation time.

(Means for solving problems) The soil stabilization method of the present invention includes (1) sodium silicate.

(2) glyoxal; (3) water-soluble aluminum salts.

and (4) injecting into soil an aqueous mixture to which at least one of a water-soluble organic acid, a water-soluble inorganic acid, and a water-soluble acidic inorganic salt is added, thereby achieving the above-mentioned purpose. is achieved.

Sodium silicate is also called water glass and is widely used to stabilize soil quality. For sodium silicate.

For example, there is No. 3 sodium silicate based on JISK-1408. The content of sodium silicate can be appropriately selected depending on the soil condition and purpose.7 For example, when using the above No. 3 sodium silicate, the content of sodium silicate is preferably 10 to 5.
It is contained in an amount of 0% by weight, more preferably in a range of 20 to 45% by weight.

Glyoxal is the simplest dialdehyde, and for industrial use there are 35% and 40% aqueous solutions.

Glyoxal reacts with the alkali in the sodium silicate to form glycolic acid, resulting in the formation of silicon dioxide gel. The 35% aqueous solution of glyoxal is contained in the aqueous mixture preferably in a range of 0.3 to 10% by weight, more preferably 0.5 to 7% by weight. When it is less than 0.3% by weight, the compressive strength of the soil after stabilization treatment tends to decrease if the gelation time is set for a long time. If it exceeds 10% by weight, it becomes expensive and uneconomical.

Water-soluble aluminum salts include, for example, aluminum sulfate, aluminum chloride, potassium alum, and sodium alum. In particular, aluminum sulfate 18 hydrate is preferable because it has good solubility and less corrosion of the injection pump. The water-soluble aluminum salt has the effect of stabilizing the gel and preventing the syneresis phenomenon, and is preferably contained in the aqueous mixture in an amount of 0.2 to 3%,
It is more preferably contained in a range of 0.3 to 2% by weight.

If it is less than 0.2% by weight, the amount of syneresis water tends to increase due to the syneresis phenomenon, which impedes the stabilization of soil quality. When it exceeds 3% by weight, a non-uniform gel is formed at the initial stage of gelation, and the permeability of the above-mentioned aqueous mixture tends to decrease.

Water-soluble organic acids include malonic acid, glutaric acid,
These include dibasic acids such as succinic acid, oxycarboxylic acids such as tartaric acid and citric acid, and acetic acid. Examples of water-soluble inorganic acids include sulfuric acid, hydrochloric acid, and phosphoric acid.

There is boric acid. Examples of water-soluble acidic inorganic salts include:
Examples include sodium dihydrogen borate, sodium dihydrogen phosphate, sodium hydrogen sulfate, potassium hydrogen sulfate, potassium dihydrogen phosphate, and potassium hydrogen sulfate. In particular, tartaric acid, citric acid, and succinic acid.

Phosphoric acid, boric acid, and sodium dihydrogen phosphate are preferred because they have good solubility and are less likely to corrode the infusion pump. Such organic acids, inorganic acids, and acidic inorganic salts have the effect of promoting gelation of sodium silicate. At least one of a water-soluble organic acid, a water-soluble inorganic acid, and a water-soluble acidic inorganic salt is added in an amount of 0.2 to 4% by weight, more preferably 0.5 to 3% by weight in the aqueous mixture. Contained within the range. If it is less than 0.2% by weight, a non-uniform gel will be formed at the initial stage of gelation, so if the gelation time is set to a short time, the compressive strength of the soil after stabilization treatment will be uneven.

When it exceeds 4% by weight, the gelation time becomes excessively short.
This makes soil stabilization work difficult.

In order to obtain an aqueous mixed solution to which the above-mentioned sodium silicate and the curing agents (2) to (4) are added, a method of mixing these surrounds with water, or a method of mixing a sodium silicate aqueous solution and other 3
There is a method in which an aqueous solution of the ingredients is prepared in advance, and then a rainwater solution is added to the soil immediately before or at the time of injection. When the gelation time is set to a very short time, the rainwater solution may be mixed in the soil. In either method, it is necessary that the aqueous mixture is not gelatinized at the time of injection into the soil.

The gelation time can be easily adjusted by changing the mixing ratio of sodium silicate and other additives in the aqueous mixture. Generally, as the ratio of other additives to sodium silicate increases, the gelation time tends to decrease. The gelling time can be adjusted by determining the relationship between the amount of additives and the gelling time in advance.

For example, an aqueous mixture with a controlled gelling time may be used.

Injected into the soil using an injection pump and injection tube.

When mixing the sodium silicate aqueous solution and other additive aqueous solutions in soil, a Y-shaped tube, for example, is used.

(Example) The present invention will be described below with reference to examples.

Sodium silicate No. 3 Sodium silicate (based on JISK-1408) 1
100 ml of water was added to 00 ml to make this solution A. Add water to 4 g of aluminum sulfate 18 hydrate, 5 g of 35% glyoxal, and 6.3 g of glutaric acid and dissolve. 200 mj! Solution B was prepared. 2 liquids A and B
The mixture was mixed in 50ml portions at 0°C, and the gelation time was measured, and it was 3 minutes and 30 seconds. The produced gel was left for one day and the amount of syneresis water was measured, and it was found to be 2.1 g. On the other hand, the unconfined compressive strength of the sand gel with this chemical solution was measured according to JISA-1216 (uniaxial compression test method for soil) and was found to be 5.8 kg/aa.

Carbonation 1 Solutions A and B were prepared in the same manner as in Example 1, except that 11.5 g of acidic sodium sulfate was used in place of glutaric acid. Using both solutions, by the same method as in Example 1,
When the gelation time, syneresis water amount, and unconfined compressive strength were measured, the gelation time was 3 minutes 20 seconds, the syneresis water amount was 1.0 g, and the unconfined compressive strength was 5.6 kg/cd. These results are shown in the table below. still.

() represents the proportion of each component in the aqueous mixture.

Solutions A and B were prepared in the same manner as in Example 1, except that citric acid was used in place of citric acid. Using both solutions, gelation time, syneresis water amount, and uniaxial compression strength were measured using the same method as in Example 1. The gelation time was 3 minutes OO seconds, the syneresis water amount was 1.1 g, and uniaxial compression The strength was 6.1 kg/cJ. These results are shown in the table below.

"Jitnyrogan" - Solutions A and B were prepared in the same manner as in Example 1, except that 7.9 g of 75% phosphoric acid was used in place of glutaric acid. Using both solutions, gelation time, syneresis water amount, and uniaxial compressive strength were measured using the same method as in Example 1. The gelation time was 3 minutes and 55 seconds.

The amount of syneresis water is 1.8g and the unconfined compressive strength is 5.6kg/
-It was. These results are shown in the table below.

Without using aluminum sulfate 18 hydrate, glutaric acid was added to 9.
Solutions A and B were prepared in the same manner as in Example 1, except that the amount was 3 g. Using both solutions, gelation time, syneresis water amount, and uniaxial compression strength were measured using the same method as in Example 1. The gelation time was 2 minutes 47 seconds, the syneresis water amount was 16.0 g, and the uniaxial compression strength was 2 minutes and 47 seconds. The strength was 5.7 kg/cj. These results are shown in the table below.

Solutions A and B were prepared in the same manner as in Example 1, except that aluminum sulfate 18 hydrate was not used and 17.1 g of acidic sodium sulfate was used in place of glutaric acid. Using both solutions, gelation time, syneresis water amount, and uniaxial compression strength were measured using the same method as in Example 1. The gelation time was 3 minutes 47 seconds, the syneresis water amount was 12.0 g, and the uniaxial compression strength was 3 minutes and 47 seconds. The strength was 5.5 kg/cJ. These results are shown in the table below.

Solution A and Solution B were prepared in the same manner as in Example 1, except that 12.0 g of citric acid was used in place of glutaric acid and without using pentaminic aluminum sulfate 18 hydrate.

Using both solutions, gelation time, syneresis water amount, and uniaxial compression strength were measured using the same method as in Example 1. The gelation time was 2 minutes 30 seconds, the syneresis water amount was 6.0 g, and the uniaxial compression strength was 2 minutes and 30 seconds. Strength is 5.4kg/co! Met. These results are shown in the table below.

Comparison ■1 Except that aluminum sulfate 18 hydrate was not used and 11.0 g of 75% phosphoric acid was used instead of glutaric acid.

Solution A and solution B were prepared in the same manner as in Example 1.

Using both solutions, gelation time, syneresis water amount, and unconfined compressive strength were measured using the same method as in Example 1. The gelation time was 3 minutes 20 seconds, the syneresis water amount was 8.0 g, and the unconfined compression strength was The intensity was 5.3 +r/-. These results are shown in the table below.

Solutions A and B were prepared in the same manner as in Example 1, except that the comparative carbonic acid was not used. Using both solutions, we tried to measure the gelation time, amount of synergic water, and uniaxial compressive strength using the same method as in Example 1, but the gel turned into an uneven gel within a few seconds, and the amount of synergic water could not be measured. In addition, it was difficult to prepare the specimen.

Solutions A and B were prepared in the same manner as in Example 1, except that 35% glyoxal was not used and 8.0 g of citric acid was used in place of glutaric acid. Using both solutions, gelation time, syneresis water amount, and unconfined compression strength were measured using the same method as in Example 1. The gelation time was 3 minutes 58 seconds, the syneresis water amount was 3.8 g, and the unconfined compression strength was 3 minutes and 58 seconds. Strength is 3.1k
g/co! Met. These results are shown in the table below.

(Application example) Soil quality was stabilized as follows.

(1) Preparation of chemical solution Add No. 3 sodium silicate (JISK) to a 20Of dissolution mixer.
-Based on 1408<) 100R and water 1001
was added, stirred, and dissolved to obtain Solution A 2001. another twenty
01 Into the dissolution mixer, 4 kg of aluminum sulfate 18 hydrate
.

35% glyoxal 5 kg and citric acid 8.1k
g, and water was added thereto to dissolve it to obtain Solution B 2001. In the same manner, 10 mm each of Solution A and Solution B were prepared. The gelation time due to mixing of liquid A and liquid B is:
As in Example 3, it took about 3 minutes.

(2) Drilling was carried out on the ground where the depth of the hole was about 4 to 5 m was a gravel layer, and the depth of about 5 to 8 m was a layer of coarse sand mixed with fine sand with a hydraulic conductivity of IXl0-2 cm/sec. Drilling was carried out to a temperature of approximately 8 m while running tap water from the tip of the rondo.

(3) Using two injection grout pumps, a mixed chemical solution 2001 of liquids A and B was injected into the ground drilled in (2) using a 1.5-shot method. The injection rate was 10j2/min for each of liquids A and B. After the injection is finished, add 1 rondo
m step up, and mixed chemical solution 200 m by the same method.
1 was injected. What is the injection pressure?

Gravel layer is 0.5~1.0kg/co! The coarse sand layer mixed with fine sand was 2.0 to 4.0 kg/cat.

(4) Observation of the consolidation status through excavation and physical property test of the consolidated material (3) The ground into which the chemical solution was injected was excavated to the injection depth, the consolidation status was observed, and the physical properties of the consolidated material were tested. . As a result, for the gravel layer.

The chemical solution was sufficiently injected into the gaps between the gravels and solidified, and no syneresis phenomenon was observed.

In addition, in the coarse sand layer mixed with fine sand, the permeation points were almost circular, indicating ideal consolidation conditions. When a physical property test was conducted on this consolidated part, the −axial compressive strength was 5.3.
kg/cJ, and the hydraulic conductivity is 1. =7, IXIQ
-'am 8e.

(Left below) As is clear from the Examples, Comparative Examples, and Application Examples, the aqueous liquid mixture used in the soil stabilization method of the present invention has a significantly small amount of syneresis water. Moreover, the stabilized ground has high unconfined compressive strength. In an aqueous liquid mixture that does not contain aluminum sulfate 18 hydrate, a large amount of syneresis water tends to be separated. An aqueous mixture containing neither organic acids nor inorganic acids nor acidic inorganic salts.

゛ After mixing, it forms a non-uniform gel within a few seconds, making it unsuitable as an injection solution. Although the aqueous mixture that does not contain 35% glyoxal has a relatively small amount of syneresis water, the uniaxial compressive strength of the stabilized ground is low.

Further, by stabilizing the ground using the soil stabilization method of the present invention, a ground with excellent -axial compressive strength and water-stopping properties can be obtained.

(Effects of the Invention) According to the soil stabilization method of the present invention, the gelation time can be easily adjusted, and as described above, since the amount of syneresis water is small, a ground with good water-stopping properties can be obtained. Stabilized ground also has superior compressive strength. Therefore, such a soil stabilization method can be effectively used for stabilizing the foundation ground, particularly for preventing leakage of groundwater and stabilizing the ground when excavating a tunnel or a tunnel.

that's all

Claims (1)

[Claims] 1. (1) Sodium silicate, (2) Glyoxal, (3) Water-soluble aluminum salt, and (4) Water-soluble organic acid, water-soluble inorganic acid, and water-soluble acidic inorganic acid. A soil stabilization method that includes injecting into soil an aqueous mixture to which at least one type of salt is added. 2. The soil stabilization method according to claim 1, wherein the water-soluble aluminum salt is at least one of aluminum sulfate, aluminum chloride, potassium alum, and sodium alum. 3. Claim 1, wherein the water-soluble organic acid is at least one of dibasic acids such as malonic acid, glutaric acid, and succinic acid, oxycarboxylic acids such as tartaric acid and citric acid, and acetic acid. The soil stabilization method described. 4. The soil stabilization method according to claim 1, wherein the water-soluble inorganic acid is at least one of sulfuric acid, hydrochloric acid, phosphoric acid, and boric acid. 5. The water-soluble acidic inorganic salt is at least one of sodium dihydrogen borate, sodium dihydrogen phosphate, sodium hydrogen sulfate, potassium hydrogen sulfate, potassium dihydrogen phosphate, and potassium hydrogen sulfate. Soil stabilization method described in Scope 1. 6. 35% of the glyoxal in the aqueous mixture
The soil stabilization method according to claim 1, wherein the aqueous solution is contained in a range of 0.3 to 10% by weight. 7. The soil stabilization method according to claim 1, wherein the water-soluble aluminum salt is contained in the aqueous mixture in a range of 0.2 to 3% by weight. 8. The aqueous mixture contains at least one of the water-soluble organic acid, water-soluble inorganic acid, and water-soluble acidic inorganic salt in a range of 0.2 to 4% by weight. Soil stabilization method described in Scope 1.