JP3226510B2 - Ground hardening method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a soil hardening method. In order to strengthen the ground and stop water, a chemical solution is mixed and injected into the ground to harden the ground. The present invention relates to an improvement in such a ground hardening method.

[0002]

2. Description of the Related Art Conventionally, as the above-described ground hardening method, generally, an acidic silica sol and an aqueous solution of an alkali agent are mixed and injected into the ground. The acidic silica sol in this case is a water dispersion in which sulfuric acid is usually added to water glass to make the pH less than 2, and a hydroxide of an alkaline earth metal such as magnesium hydroxide or calcium hydroxide is usually used as an alkali agent. (Tokuhei 3-2451)
5). However, the conventional method has a problem that since a large amount of sulfuric acid, which is a deleterious substance, is used, its handling is extremely troublesome, and as a result, a large amount of undesired sulfate groups is brought into the ground. In addition, since an aqueous solution of a strong alkaline agent such as magnesium hydroxide or calcium hydroxide is mixed with a strongly acidic silica sol having a pH of less than 2 by adding sulfuric acid to water glass, the pH of the entire chemical solution after mixing tends to fluctuate. In addition, there is a problem that the time required for gelling the water glass injected into the ground (gel time) is greatly disturbed.

In the ground hardening method using water glass, the ground is hardened by utilizing the gelation of water glass injected into the ground. In this case, the gel time of the water glass is known to be greatly affected by the pH, though it depends on the SiO ₂ concentration and the curing temperature of the water glass. When, for example, sulfuric acid is gradually added as a hardening agent to water glass, and the pH is sequentially lowered, the water glass generally becomes a so-called flashing state in which gelation occurs at pH 6.0 to 9.0 in several seconds to several tens of seconds, Also p
When H is less than 4.5 to 6.0, a so-called sintering state occurs in which gelation occurs in several minutes to several tens of minutes, and when pH is less than 3.0 to 4.5, a so-called sintering state in which gelation occurs in several hours to tens of hours And below pH 2 a stable acidic silica sol. The gel time of water glass becomes logarithmically longer in relation to pH in a pH range lower than the neutral range around pH 6.0 to 9.0, and becomes a stable acidic silica sol at a pH lower than 2.

When the pH of the whole chemical solution injected into the ground fluctuates as in the above-mentioned conventional method, the gel time of water glass injected as acidic silica sol into the ground is greatly disturbed, and the time required for hardening the ground is disturbed. It interferes with the progress of other work scheduled before and after the work.

[0005] In order to improve the fluctuation of the pH of the whole chemical solution injected into the ground, an adjusting agent such as an alkali metal hexametaphosphate is also used together with the alkali agent (Japanese Patent Publication No. 3-24515, Japanese Patent Publication No. Hei 4-4). −5607
4). However, even with this conventional method, although the fluctuation of pH can be correspondingly improved as compared with the above-mentioned conventional method using only an aqueous solution of a strong alkaline agent, there is a problem that the degree of the improvement is insufficient, and still water glass has a problem. There is the same problem as the above-mentioned conventional method due to the use of a strongly acidic silica sol having a pH of less than 2 by adding sulfuric acid.

[0006]

The problems to be solved by the present invention are as follows. In the conventional method, 1) a large amount of sulfuric acid, which is a deleterious substance, is used for preparing acidic silica sol of water glass, so that the handling thereof is difficult. It is very troublesome, 2) as a result, a large amount of undesired sulfate is brought into the ground, and 3) the pH of the whole chemical solution injected into the ground is easy to fluctuate, and water glass is injected as an acidic silica sol. Are the points where the gel time is disturbed.

[0007]

According to the present invention, there is provided a method of hardening a ground by mixing and injecting a chemical into the ground, wherein an aqueous solution of water glass and an aqueous solution of a hardener are used as the chemical. And a soil hardening method using an inorganic acid and sodium tripolyphosphate and / or sodium tetrapolyphosphate as the hardener. Further, the present invention provides a method for curing a ground by mixing and injecting a chemical solution into the ground, wherein an aqueous solution of water glass and an aqueous solution of a curing agent are used as the chemical solution, and as the curing agent, an inorganic acid, aluminum sulfate and And / or a sodium hardening method characterized by using polyaluminum chloride and sodium tripolyphosphate and / or sodium tetrapolyphosphate.

In the present invention, an aqueous solution of water glass (solution A)
And an aqueous solution (solution B) of a curing agent are mixed and injected into the ground. The mixed injection is 1) a method in which both are mixed immediately before injection and then injection (1 shot method), 2) a method in which both are mixed while being injected halfway (1.5 shot method), 3) both injections Any method of mixing immediately after (two-shot method) may be used. In general, one injection pipe is used in the method 1), one Y-shaped injection pipe is used in the method 2), and two injection pipes or double injection pipes are used in the method 3). Use an injection tube.

As the water glass used for preparing the aqueous solution of water glass as the liquid A, any commercially available water glass can be used. Normally, water glass of JIS No. 3 is used.
water glass of SiO ₂ high molar ratio containing SiO ₂ in a proportion of 3.6 to 4.5 mol with respect to a ₂ O1 moles can be used.

[0010] The curing agent used for preparing the aqueous solution of the curing agent as the liquid B includes: 1) a combination of an inorganic acid and sodium tripolyphosphate and / or sodium tetrapolyphosphate;
2) a combination of an inorganic acid, aluminum sulfate and / or polyaluminum chloride, and sodium tripolyphosphate and / or sodium tetrapolyphosphate; As the inorganic acid, hydrochloric acid, nitric acid, sulfuric acid and the like can be used, but usually, economical sulfuric acid is used. In preparing such an aqueous solution of the curing agent, other adjusting agents such as alum and disodium hydrogen phosphate hydrate (Na ₂ HPO ₄ .12H ₂ O) can be used in combination.
When an aluminum salt is used as a curing agent, a strong and highly durable aluminum silicate is formed.

In the present invention, an aqueous solution of water glass is prepared as one chemical solution (solution A) to be injected into the ground, and an aqueous solution of a curing agent is prepared as the other chemical solution (solution B). Mix and inject into the ground with. By adjusting the composition and concentration of Solution A and Solution B, and also the mixing and injection ratio of both, the pH of the whole chemical mixed and injected into the ground can be arbitrarily controlled, and therefore the gel time of the water glass injected into the ground can be reduced. Can be arbitrarily controlled.

At the site of the ground hardening work, the ground hardening work itself is generally performed as intended, and the water glass injected into the ground is often interlinked in order to smoothly advance the front and rear work. Water glass poured into the ground for several minutes ~
As described above, it is necessary to adjust the pH of the whole drug solution to be injected into the ground to 4.5 to less than 6.0 in the case of gelling with tens of minutes. In this case, although it depends on the composition of other agents used together with the inorganic acid as the curing agent, the amount of sulfuric acid usually used as the inorganic acid is minimized as much as possible, so that the amount of sulfate groups that are brought into the ground is minimized. Therefore, the amount of sulfuric acid used depends on the pH of the aqueous solution of water glass.
Is preferably adjusted to at least 3.0 to less than 4.5, and more preferably adjusted to 6.0 to 9.0 (in other words, to an amount that substantially neutralizes the aqueous solution of water glass). More preferred.

In the above case, specifically, when sulfuric acid and sodium tripolyphosphate and / or sodium tetrapolyphosphate are used as the curing agent, the sulfuric acid is added in an amount of 0.9 to 0.9 mol per mol of Na ₂ O in the water glass. It is used in a ratio of 1.2 mol, and sodium tripolyphosphate and / or sodium tetrapolyphosphate is used in a ratio of 0.004 to 0.2 mol. The amount of sulfuric acid used in this case is an amount for adjusting the pH of the aqueous solution of water glass to less than 3.0 to less than 4.5, and the amount of sodium tripolyphosphate and / or sodium tetrapolyphosphate used in the ground This is an amount for adjusting the pH of the whole drug solution to be injected to 4.5 to less than 6.0.

When sulfuric acid, aluminum sulfate and / or polyaluminum chloride, and sodium tripolyphosphate and / or sodium tetrapolyphosphate are used as the curing agent, sulfuric acid is added in an amount of 0.1 mol per mol of Na ₂ O in water glass. Aluminum sulfate and / or polyaluminum chloride are used in an amount of 0.002 to 7 mol.
0.14 mol of sodium tripolyphosphate and / or sodium tetrapolyphosphate is used in an amount of 0.004 mol.
It is used in a ratio of 4 to 0.2 mol. In this case, the polyaluminum chloride is generally [Al (OH) _1.5 Cl _1.25 (S
O ₄ ) _0.125 ] _n , so that the amount used is Al (O
H) It is a value converted to _1.5 Cl _1.25 (SO ₄ ) _0.125 (the same _applies to the use amount of polyaluminum chloride). The amount of sulfuric acid used in the above case is an amount for adjusting the pH of the aqueous solution of water glass to 6.0 to 9.0, and the amount of aluminum sulfate and / or polyaluminum chloride used is the same as that of the aqueous solution of water glass. PH of the mixture with sulfuric acid is 3.0
The amount of sodium tripolyphosphate and / or the amount of sodium tetrapolyphosphate used is 4.5 to less than 4.5.
The amount is adjusted to be less than 6.0.

In the present invention, a strongly acidic silica sol having a pH of less than 2 by adding sulfuric acid to water glass is not used as a chemical solution to be injected into the ground as in the conventional method. And the amount of sulfuric acid used can be significantly reduced, and the amount of sulfate groups that are brought into the ground can be significantly reduced. Moreover, unlike the conventional method, a strong alkaline agent such as magnesium hydroxide or calcium hydroxide is not used, and sodium tripolyphosphate and / or sodium tetrapolyphosphate, or further, aluminum sulfate and / or polyaluminum chloride is used. To do
Due to these pH buffering capabilities, even if the water glass or sulfuric acid used as a material has a considerable variation, the pH fluctuation of the whole chemical injected into the ground can be reduced, and the gel time of the water glass injected into the ground can be reduced. Can be controlled as expected.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention include the following examples. 1) Water is added to 100 liters of JIS No. 3 water glass to prepare 200 liters of an aqueous solution of water glass (A)
liquid). Separately, 5 kg of sodium tripolyphosphate and water are added to 16 liters of 78% sulfuric acid, and an aqueous solution of a curing agent 20
Prepare 0 liter (Solution B). A method in which A liquid and B liquid are mixed and injected into the ground at an equal ratio. In this case, the sulfuric acid in the liquid B corresponds to 1.04 mol and the sodium tripolyphosphate corresponds to 0.065 mol per 1 mol of Na ₂ O in the liquid A. In the test under the same conditions, the pH of the whole drug solution was 5.2, and the gel time was 3 minutes.

2) Water is added to 100 liters of JIS No. 3 water glass to prepare 200 liters of an aqueous solution of water glass (Solution A). Separately, 6 kg of sodium tetrapolyphosphate and water are added to 16 liters of 78% sulfuric acid to prepare 200 liters of an aqueous solution of a curing agent (Solution B). Liquid A and B
A method of mixing and injecting liquid into the ground at an equal ratio. In this case, the sulfuric acid in the liquid B corresponds to 1.04 mol, and the sodium tetrapolyphosphate corresponds to 0.061 mol per mol of Na ₂ O in the liquid A. In the test under the same conditions, the pH of the whole drug solution was 5.3, and the gel time was 2 minutes.

3) SiO ₂ is added per mole of Na ₂ O.
Water glass with high molar ratio of SiO ₂ containing 8 moles 1
Water is added to 00 liters, and an aqueous solution of water glass 200
Prepare liter (Solution A). Separately, 4 kg of 17% aluminum sulfate, 0.5 kg of sodium tripolyphosphate and water are added to 7 liters of 78% sulfuric acid, and an aqueous solution of a curing agent 2 is added.
Prepare 00 liter (Solution B). A method in which A liquid and B liquid are mixed and injected into the ground at an equal ratio. In this case, the sulfuric acid in the liquid B corresponds to 0.8 mol, the aluminum sulfate corresponds to 0.06 mol, and the sodium tripolyphosphate corresponds to 0.01 mol per mol of Na ₂ O in the liquid A. I do. In the test under the same conditions, the pH of the whole drug solution was 5.3 and the gel time was 5 minutes.

[0019]

EXAMPLES Test Category 1 Example 1 Water was added to 100 ml of JIS No. 3 water glass to prepare 200 ml of an aqueous solution of water glass (Solution A). Separately, 78%
To 16 ml of sulfuric acid, 5 g of sodium tripolyphosphate and water were added to prepare 200 ml of an aqueous solution of a curing agent (Solution B).
The liquid A and the liquid B were mixed at an equal ratio. In this case, the amount of sulfuric acid in the solution B was 1.04 mole, and the amount of sodium tripolyphosphate was 0.06 mole per mole of Na ₂ O in the solution A.
This corresponds to 5 moles. The pH of the whole mixed drug solution was 5.2, and the gel time was 3 minutes.

Example 2 Water was added to 100 ml of water glass having a high molar ratio of SiO ₂ containing 3.8 mol of SiO ₂ to 1 mol of Na ₂ O to prepare 200 ml of an aqueous solution of water glass ( A liquid).
Separately, 4 g of 17% aluminum sulfate, 0.5 g of sodium tripolyphosphate and water were added to 7.0 ml of 78% sulfuric acid to prepare 200 ml of an aqueous solution of a curing agent (solution B). The liquid A and the liquid B were mixed at an equal ratio. In this case, the sulfuric acid in the liquid B corresponds to 0.8 mol, and the aluminum sulfate corresponds to 0.06 mol, per 1 mol of Na ₂ O in the liquid A.
Sodium tripolyphosphate corresponds to 0.01 mol.
The pH of the whole mixed drug solution was 5.3, and the gel time was 5 minutes.

Test Category 2 Water was added to 100 ml of water glass having a high molar ratio of SiO ₂ containing 3.8 mol of SiO ₂ to 1 mol of Na ₂ O to prepare 200 ml of an aqueous solution of water glass ( A liquid).
Separately, 4 ml of 17% aluminum sulfate in 78 ml of 78% sulfuric acid
And Yg of sodium tripolyphosphate and water were added to prepare a 200 ml aqueous solution of a curing agent (Solution B). The liquid A and the liquid B were mixed at an equal ratio. The gel time of the water glass at that time was determined by changing the above X and Y. The results are shown in FIG. In FIG. 1, the horizontal axis indicates the amount of addition of sodium tripolyphosphate Y (g), and the vertical axis indicates the gel time (minute) of water glass.
Shows the relationship between the gel time and the gel time. In FIG.
1 is 7.0 ml when the added amount X of 78% sulfuric acid is 7.0 ml, 2 is 7.
For 2 ml, 3 is for 7.4 ml and 4 is for 7.6 ml. As is clear from the results of FIG. 1, according to the present invention, the gel time of the water glass injected into the ground can be reliably controlled.

[0022]

As is clear from the above description, the present invention described above comprises a strongly acidic silica sol which is prepared by adding a large amount of sulfuric acid to water glass to a pH of less than 2, as in the conventional method, as a chemical solution to be injected into the ground. Since sulfur is not used, even when sulfuric acid is used as the inorganic acid, the amount of sulfuric acid used can be significantly reduced, and the amount of sulfate groups brought into the ground can be significantly reduced. Moreover, unlike the conventional method, a strong alkaline agent such as magnesium hydroxide or calcium hydroxide is not used, and sodium tripolyphosphate and / or sodium tetrapolyphosphate, or further, aluminum sulfate and / or polyaluminum chloride is used. Therefore, due to these pH buffering capabilities, there is an effect that the fluctuation of the pH of the whole chemical injected into the ground is reduced, and the gel time of the water glass injected into the ground can be controlled as expected.

[Brief description of the drawings]

FIG. 1 is a graph showing the gel time (minute) of water glass with respect to the composition of a curing agent in the present invention in a semilogarithmic scale.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-125310 (JP, A) JP-A-59-196388 (JP, A) JP-A-59-140285 (JP, A) JP-A-60-1985 233192 (JP, A) JP-A-11-61127 (JP, A) JP-A-10-338876 (JP, A) JP-A-10-245556 (JP, A) JP-A-6-88330 (JP, A) JP-A-7-258638 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09K 17/12 C09K 17/08 E02D 3/12 101 C09K 103: 00 C09K 107: 00

Claims (4)

(57) [Claims] 1. A method for hardening a ground by mixing and injecting a chemical solution into the ground, wherein an aqueous solution of water glass and an aqueous solution of a hardener are used as the chemical solution, and an inorganic acid and sodium tripolyphosphate are used as the hardener. And / or using sodium tetrapolyphosphate. 2. As a hardening agent, Na ₂ O 1 in water glass is used.
Per mole, ground curing method of claim 1, wherein a ratio of 0.9 to 1.2 mol, and sodium tripolyphosphate and / or a tetrapolyphosphate sodium used in a proportion of from 0.004 to 0.2 mole of sulfuric acid. 3. A method of hardening the ground by mixing and injecting a chemical solution into the ground, wherein an aqueous solution of water glass and an aqueous solution of a hardener are used as the chemical solution, and an inorganic acid, aluminum sulfate and aluminum sulfate are used as the hardener. And / or using sodium polypolychloride and sodium tripolyphosphate and / or sodium tetrapolyphosphate. 4. A hardening agent comprising Na ₂ O 1 in water glass.
Sulfuric acid is used in a ratio of 0.7 to 1.0 mole per mole, and aluminum sulfate and / or polyaluminum chloride is used, provided that polyaluminum chloride is Al (OH) _1.5 Cl
_1.25 (SO ₄ ) Converted to _0.125 and 0.002 to 0.14
The soil hardening method according to claim 3, wherein sodium tripolyphosphate and / or sodium tetrapolyphosphate is used in a molar ratio of 0.004 to 0.2 mol.