JPS5833277B2 - Soil stabilization treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention injects a sodium silicate (water glass)-based grout agent into soil and gels it to bind and solidify soil particles, thereby strengthening the soil and making it impermeable to liquids. The present invention relates to a method for performing stabilization processing.

It is well known that soil quality can be stabilized by grouting agents using sodium silicate.

As a water glass grouting agent using sodium silicate, a water glass-cement suspension type or a solution type grout consisting of water glass and a water-soluble hardening agent are used.

Among the above, regarding the water glass-cement suspension type,
There have been problems such as cement particles settling over time, poor penetration due to the filtration action of soil particles when injected into soil, and difficulty in adjusting the gelation time.

On the other hand, solution-type products use acids, water-soluble inorganic salts, amides, alcohols, esters, aldehydes, etc. as hardening agents, and are widely used because they can be applied to fine-grained soils.

However, products using acids or water-soluble inorganic salts have instant setting properties, making it difficult to adjust the gelation time, and the gelation time fluctuates widely due to small changes in the mixing ratio of the curing agent. It has the following drawback.

In addition, organic curing agents using amides, alcohols, esters, aldehydes, etc. can be used to adjust the gelation time to a certain extent, but in order to shorten the gelation time, it is necessary to use a large amount. Not only is it inferior in economical efficiency, but also gelation strength decreases and syneresis increases when used in large amounts.

In addition, many of these organic curing agents are classified as dangerous substances, with low flash points that pose a fire risk, strong irritating odors, and many of which are harmful to the human body, making them unsuitable for practical use. There are many problems in making it available.

In addition, in order to use a water glass-based grouting agent to stabilize soil, generally the water glass and hardening agent are diluted and dissolved separately in water and adjusted to a predetermined concentration. It is mixed in a pipe and injected into the soil.

At this time, the water glass aqueous solution and the hardening agent aqueous solution must always be mixed at a predetermined ratio, but it is difficult to maintain an accurately constant mixing ratio, and this may be due to mechanical factors of the injection device or other reasons. It is often difficult to avoid variations in the blending ratio.

Due to variations in the above-mentioned compounding ratio, especially when an inorganic curing agent is used, the gelation time may vary greatly. The gelation time becomes extremely long,
In some cases, gelation may not occur.

If the gelation time is short, the permeation range of the grout solution into the soil will be narrowed, and the intended purpose may not be achieved.If the gelation time is too long, the grout solution may be diluted with groundwater.
There are also cases where the soil is washed away and does not harden, making it impossible to achieve the goal of stabilizing the soil quality.

As described above, the gelation time has a great influence on the consolidation state of the soil, so large fluctuations in the preset gelation time are a serious problem that greatly affects the entire injection design.

Therefore, even if the blending ratio of the two liquids varies slightly, it is necessary to prevent the gelation time from widely varying as much as possible.

The present invention has been developed in consideration of the above-mentioned drawbacks of the conventional soil stabilization treatment method using sodium silicate-based grouting chemicals.
A safe inorganic compound with volatility and bad odor is used as a curing agent, and the gelation time can be easily adjusted, that is, the gelation time can be adjusted arbitrarily from several tens of seconds to several tens of seconds. It is possible to prevent the gelation time from fluctuating widely due to a small amount of variation in the formulation, and furthermore, the gelation time is not greatly affected by temperature changes. Furthermore, it is an object of the present invention to provide a stabilization treatment method that always exhibits constant and high unconfined compressive strength and high water-stopping performance regardless of the length of gelation time.

Therefore, the gist of the present invention is as follows: Number of people: A mixed solution of sodium silicate and one or more salts selected from alkali sulfites and alkali carbonates.Liquid B: alkali bisulfite, alkali bisulfate, alkali bicarbonate, hydrogen phosphate. The present invention relates to a method for stabilizing soil quality, which comprises mixing the aqueous solutions A and B containing at least one compound selected from alkali and alkali pyrosulfate and immediately injecting the mixture into the soil.

In the above, sodium silicate is also known as water glass and has been traditionally used to stabilize soil quality.

The amount of sodium silicate used may be determined as appropriate depending on the condition of the soil to be injected and the purpose.
When using No. 3 sodium silicate for ISK1408, it is preferable to mix it with water so that the sodium silicate accounts for 10 to 60% by weight of the total amount of the injection solution, that is, both solutions A and B. .

Next, in the present invention, one or more salts selected from alkali sulfite, alkali sulfate, and alkali carbonate are mixed with the aqueous sodium silicate solution and used as liquid A. Regarding the amount used, if it is too small, it will not only be difficult to control the gelation time, but also the ability to suppress fluctuations in the gelation time when the blending ratio varies, and if it is too large, it will not be possible to stabilize the gelation time. Since the compressive strength of the soil tends to decrease, the amount of 0.1~
It is preferable to use an amount within a range of 10% by weight. Examples of the above salts preferably used in the present invention include:
Sodium sulfite, potassium sulfite, sodium sulfate,
Examples include potassium sulfate, sodium carbonate, potassium carbonate, potassium sodium carbonate, and the like.

Next, in the present invention, an aqueous solution containing a compound selected from alkali bisulfite, alkali bisulfate, alkali bicarbonate, alkali hydrogen phosphate, and alkali pyrosulfate is used as liquid B. It has been conventionally known as a hardening agent for grouting agents containing sodium silicate as a main ingredient, and also acts as a hardening agent for aqueous sodium silicate solutions in the present invention.

Specific examples of the above compounds suitable for use in the present invention include sodium bisulfite, potassium bisulfite, sodium bisulfate, potassium bisulfate, sodium bicarbonate, potassium bicarbonate, sodium dihydrogen phosphate, potassium dihydrogen phosphate,
Examples include sodium pyrosulfate and potassium pyrosulfate.

The amount used is preferably 0.1 to 15% by weight based on the entire injection solution.

In addition, in the present invention, one or more water-soluble inorganic salts may be further included in the B solution containing the above compound, and by using the inorganic salts in combination in this way, the gelation time can be increased. It becomes easier to adjust, syneresis is further reduced, and the compressive strength of the stabilized soil is further improved.

Examples of the above-mentioned inorganic salts suitable for use in the present invention include sodium chloride, potassium chloride, aluminum chloride,
Chlorides such as calcium chloride, magnesium chloride, iron chloride, sulfates such as magnesium sulfate, aluminum sulfate, iron sulfate, phosphates such as sodium phosphate, potassium phosphate, aluminum phosphate, potassium sodium phosphate, pyrophosphoric acid Examples include pyrophosphates such as sodium and potassium pyrophosphate; borates and metaborates such as sodium borate, potassium borate, sodium metaborate, and potassium metaborate; alums such as sodium alum and potassium alum; and the like.

The amount of these inorganic salts used is 0 for the entire injection solution.
．． It is preferable to use it in a range of 1 to 15% by weight.

Next, in order to stabilize soil quality according to the present invention, the above-mentioned liquids A and B are mixed and immediately injected into the soil.

Injecting the mixed solution of both solutions A and B into the soil is usually carried out by using an injection pump and pressurizing the mixture through a pipe inserted into the soil.

In the present invention, A is prepared separately. It is preferable to simultaneously send fixed amounts of both liquids B to the injection pipe, where they are brought together and mixed.

In this way, the mixed solution injected into the soil becomes a water-containing gel when the preset gelation time due to the additives contained therein is reached, and the mixed solution immobilizes the soil particles in the area into which it is injected. In addition to imparting high unconfined compressive strength, the soil is stabilized by imparting liquid impermeability.

In the present invention, the gelation time of the injection solution can be easily adjusted by increasing or decreasing the amount of salt contained in Solution A.

Of course, the gelation time can also be adjusted by increasing or decreasing the amount of curing agent in liquid B.

Furthermore, during injection, it is unavoidable that there will be variations in the blending ratio of liquids A and B, but in the present invention, variations in gelation time due to variations in the blending ratio can be eliminated from variations in the conventional method. This means that it can be compressed into a narrower width.

As described above, the soil stabilization treatment method of the present invention is characterized by mixing the above-mentioned liquids A and B and immediately injecting the mixture into the soil. In addition, it is easy to set the gelation time to an arbitrary time, and it is possible to avoid the wide range of gelation times seen in conventional methods due to variations in the mixing ratio of liquids A and B that are difficult to avoid during construction. Soil stabilization treatment can be carried out reliably in a stable state without any fluctuations.

In addition, the present invention does not require the use of harmful or dangerous organic additives, making it highly practical.
The syneresis of the resulting gel is also comparable to conventional methods.

Examples of the present invention and comparative examples will be described below.

Example I According to JIS K1408, an aqueous solution (Liquid A) prepared by adding water and the indicated amounts of each component shown as the A liquid composition in Table 1 to 25 cc of No. 3 sodium silicate and making it 50 cc. An aqueous solution (Liquid B) was prepared by adding the indicated amount of water to each fraction shown as the composition of Liquid B to make 59 cc.

Next, the temperatures of liquids A and B were adjusted to 20°C, and the volume ratio of liquids A and B was 1=1.0.9:1.
When the gelation time was measured by adding three ratios of 1:1, 1.1:0.9, the gelation time was as shown in the table.

Example 2 Add water to 25 cc of sodium silicate as in Example 1 and add A to Table 2.
Add the indicated amount of each component shown as the liquid composition to make 50 cc of an aqueous solution (Liquid A), and add the indicated amount of each component shown as the B solution composition in the same table and add water. In addition, an aqueous solution (solution B) made up to 5Qcc was prepared.

Next, the temperatures of Solution A and Bl were adjusted to 20° C., and then both solutions were added at a volume ratio of 1:1, and the gelation time was measured as shown in Table 2.

Example 3 An aqueous solution prepared by adding 3.0 g of sodium carbonate to 25 cc of sodium silicate as in Example 1 and adding water to make a total volume of 50 cc (liquid A → and 2 ml of sodium bisulfate in 50 cc) .759 and aluminum sulfate 0.75
Prepare an aqueous solution (liquid B) adjusted to contain
When the gelation time was measured, the gelation time was 7 minutes.

Next, 300 cc of a mixed solution of the two solutions mixed at a volume ratio of 1:1 was infiltrated into Toyoura Standard Sand 601 and tamped and hardened to a porosity of 40E%.

After curing this cured product in a paper mixer for 2 days, the unconfined compressive strength was measured, and the strength was 4.1 kg/cr? It was t.

Comparative Example 1 An aqueous solution made by adding water to 25 cc of No. 3 sodium silicate, the same as used in Example 1, to make 50 cc (Liquid A → and each portion shown as the composition of Liquid B in Table 3) Take the indicated amount and add water to make 59cc of aqueous solution (liquid B)
After adjusting the liquid temperature of both A and B to 20°C, they were added in the same manner as in Example 1, and the gelation time was measured, and the results shown in the table were obtained. It was done.

Comparative Example 2 Add water to 25cc of sodium silicate, the same as in Example 1, and make 50cc.
Prepare an aqueous solution (Bib) of the aqueous solution M (A solution) prepared as c and the indicated amount of each fraction shown as the B solution composition in Table 4 and add water to make 50CC. After adjusting both solutions to 20'C, the volume ratio was 1:1.
The gelation time was measured at a ratio of .

The results were as shown in Table 4.

Claims (1)

[Claims] 1 Human fluid: A mixed liquid of sodium silicate and one or more salts selected from alkali sulfites and alkali carbonates. Solution B: an aqueous solution containing one or more compounds selected from alkali bisulfite, alkali bisulfate, alkali bicarbonate, alkali hydrogen phosphate, and alkali pyrosulfate. A method for stabilizing soil quality, which comprises mixing the above solutions A and B and immediately injecting the mixture into the soil. 2 The amount of salt in solution A is 0.0% relative to the total amount of both solutions A and B.
The stabilization treatment method according to claim 1, wherein the amount is 1 to 10% by weight. 3. The stabilization treatment method according to claim 1, wherein the amount of the compound in liquid B is 0.1 to 15% by weight based on the total amount of both liquids A and B.