JPS6123683A - Soil stabilization - Google Patents

Abstract

PURPOSE:To obtain soil having excellent water stopping properties and compression strength, by mixing an aq. soln. of aluminum-modified sodium silicate with water contg. a curing accelerator and introducing the mixture into soil. CONSTITUTION:An aq. soln. (A) contg. 20-50wt% aluminum-modified sodium silicate in a molar ratio of Na2O to SiO2 of 1-2.8 and Al (in terms of Al2O3) to SiO2 of 0.01-0.1 is mixed with water (B) contg. at least one curing accelerator selected from among water-soluble inorg. acids (e.g. sulfuric acid) or salts thereof (e.g. Na2SO4), water-insoluble or difficultly water-soluble bivalent or polyvalent metal salts (e.g. CaSO4), cement, glyoxal, gamma-butyrolactone, ethylene carbonate, acetate of polyhydric alcohols and water-soluble org. acids in such a proportion as to give 1-35pts.wt. curing accelerator per 100pts.wt. mixture. The mixture is introduced into soil.

Description

[Detailed Description of the Invention] (]) Industrial Application Field The present invention relates to a sodium silicate (water glass) grouting chemical solution,
More specifically, it relates to a method for stabilizing the soil by injecting an aluminum-modified sodium silicate aqueous gracto chemical into the soil and solidifying the soil particles to strengthen the soil and make it impermeable to liquids.

(2) Prior Art It is widely known that soil stabilization treatment is performed using a grafting chemical solution mainly containing sodium silicate.

Graft chemical solutions containing sodium silicate can be roughly divided into two types: a suspension type based on sodium silicate and cement, and a solution type based on sodium silicate and a water-soluble curing agent. However, with the construction methods that use these chemicals, it is difficult to control the gelation time due to the instant setting of the chemicals, and the injection of the chemicals,
After gelation, syneresis development often occurs, resulting in a significant decrease in the compressive strength of the soil and a decrease in water-stopping properties.

On the other hand, in recent years, when fine-grained soil and coarse-grained soil coexist, first the suspension-type chemical is injected to solidify the coarse-grained soil, and then the solution-type chemical is injected to improve the fine-grained soil. By consolidating the ground, a construction method was adopted to unify and stabilize the ground, which had a mixture of various open spaces of different density. However, in the case of this method, the solution-type chemical solution comes into contact with the gel generated by the previously injected suspension-type chemical solution, and the alkaline content is eluted from the gel.
In many cases, there is a very serious drawback that the temporarily solidified solution-type chemical solution dissolves, for example, after several days due to the action of the alkali.

(3) Purpose of the Invention The purpose of the present invention is to provide a soil stabilization method that allows easy adjustment of gelation time, does not cause syneresis, and provides soil with good water-stopping properties and good compressive strength. ,
Furthermore, even if all solution-type chemicals are applied after the soil is stabilized with a cement-based chemical, the gelled chemical will not dissolve again, making this soil stabilization method particularly suitable for coarse-dense mixed soils. Our goal is to provide the following.

(4) Structure of the Invention Summary of the Invention d Solution A: The molar ratio of silicon dioxide to sodium oxide and licum is 1-28, and the molar ratio of aluminum to silicon dioxide □2 when converted to aluminum oxide. An aluminum-modified sodium silicate aqueous solution having a concentration of about 20 to 50% by weight, where a01 to (Ll).

Solution B 3)) Water-soluble inorganic acid or water-soluble inorganic salt (2) Water-insoluble or water-releasable salt of divalent or higher metal (3) Cement and (4) Glyoxal, r-butyllactone, ethylene carbonate , an acetate ester of a polyhydric alcohol, or a water-soluble organic acid.

The present invention relates to a soil stabilization method characterized by injecting a chemical solution obtained by mixing the above A and B solutions into soil.

The chemical solution used in the present invention is obtained by mixing the above-mentioned A1B solutions, and an aqueous aluminum-modified sodium silicate solution with a specified blending ratio for each modification is used as the main side (solution A). A liquid in which a curing accelerator is dissolved or dispersed in water is used as the curing side (liquid B).

The aluminum modified sodium silicate aqueous solution (hereinafter appropriately abbreviated as aluminum modified solution) used in the present invention is:
It is an aqueous solution with excellent storage stability made by dissolving aluminum ions together with sodium silicate in water, and is usually uniform and transparent.

If the molar ratio d of aluminum to silicon dioxide in terms of aluminum oxide is too low, it will be difficult to harden even if water is added to the aluminum modified solution, and if it is too high, precipitates will be easily formed, so a01~0 .1. The molar ratio of silicon dioxide to sodium oxide is set to 1 to 28 because if it is too low, the chemical solution tends to harden too quickly, and if it is too high, it is difficult to produce the aluminum modified solution itself. Ru.

Furthermore, the concentration of aluminum modified aqueous solution is approximately 20-50%.
It is said that This is because if the concentration is too low, gelation will occur, similar to when water is added as a curing side to an aluminum modified solution with an appropriate concentration, and if the concentration is too high, the viscosity of the aluminum modified solution will be too high to be used for practical use. It is.

In order to obtain such an aluminum-modified aqueous sodium silicate solution, it is preferable to mix, for example, a sodium silicate aqueous solution and a sodium aluminate aqueous solution or a potassium aluminate aqueous solution continuously at a fixed ratio. A method of gradually adding and mixing an aqueous dispersion of aluminum oxide or aluminum silicate while heating and stirring may also be adopted. The sodium silicate aqueous solution at this time is preferably a No. 1 product or a No. 2 product based on JIS K1408 in which the molar ratio of silicon dioxide to sodium oxide is 2 & 5 or less, but it is not limited to these.

The chemical solution used in the present invention can be obtained by adding water to Solution A to dilute the concentration to less than about 20%. However, excessive dilution tends to weaken the strength of the glucide obtained. The concentration after dilution is about 10% or more. If you want to further shorten the gluing time or obtain soil with high compressive strength, you can combine the liquid containing the hardening accelerator described in (1) to (41) in the B liquid with the A liquid. In this case, it is not necessary to dilute the concentration of the chemical solution to less than 20%, and generally 15 to 3
It should be about 0%.

Specific examples of water-soluble inorganic acids (1) used as curing accelerators include sulfuric acid, hydrochloric acid, phosphoric acid, boric acid which is easily soluble in hot water, and water-soluble inorganic salts such as I'i NaJ3.
0. % Na, Co,,'NazPO4, Na, 50
4. NaCI, Nal, K* COx, K, PO,,
Normal salts of alkaline metals such as Kcl, Kl, LiCl,
NaHIBOl, NaHCOa, NaJHPO4,
NaH1PO4, NaHSOs, Kl(Co,,
Acidic salts of alkali metals such as K, HPO,, KH, PO,, K) ISO, 'g (Now )t, Mg5O
,, MgC+, , mono-alkaline earth metal positive salts such as CaCIt, AIPO,, AIs (504)! , AICIm
Aluminum compounds such as Fe50 and Fez (S04)
In addition to iron salts such as s, FeCl, etc., ZnCIz, NaAl0t
, N5AIC5Oa) x, N 815201w K, F
Examples include e(CN)a.

Specific examples of the water-insoluble or slightly water-soluble divalent or higher metal salts in (2) include calcium sulfate, calcium hydroxide, calcium carbonate, dolomite plaster, etc., and the cement in (3) above. Examples include boltland cement, alumina cement, blast furnace cement, ply ash cement, and silica cement.

Specific examples of the organic compound in (4) above include glyoxal, γ-butyl lactone, ethylene carbonate, polyhydric alcohol acetate such as mono- or diacetate of ethylene glycol, triacetylglycerin,
Examples include water-soluble organic acids such as acetic acid, citric acid, lactic acid, and tartaric acid.

These can be used alone or in combination, (1)
Normal salt or acid salt of alkali metal or normal salt of alkaline earth metal (2) Calcium sulfate, hydroxylated calcium carbonate (3) Bortland cement (4) Acetic acid, citric acid, lactic acid or tartaric acid, etc. Preferably used. For soil damage where fine-grained soil and coarse-grained soil are mixed,
After first applying cement as a hardening accelerator, the above +1
1, (2) or (4) curing accelerator may be used immediately.

When an acid salt of an alkali metal is used as a curing accelerator, the pH of the final KN chemical gel does not become much higher than when a conventional water glass-based chemical is used (for example, P
H13), therefore it is environmentally preferable for soil stabilization work.

The amount of the curing accelerator used depends on the concentration of liquid A and the ratio of each component, but it is usually 1 part by weight in 100 parts by weight of the mixed chemical solution of A% liquid B.
~35 parts by weight.

When stabilizing soil quality using the method of the present invention, a chemical solution obtained by mixing the above-mentioned solutions A and B is injected into the soil to be stabilized, and the chemical solution is injected into the soil. There are no restrictions on the method of injection or the injection device. That is, a two-component systematic injection (in this case, Mt5 shot injection) is preferably adopted, in which a pump is used to simultaneously send and mix fixed amounts of the A and B solutions to the Y-shaped W immediately before injection into the soil. If the gelation time is short, it is possible to use the two-shot method of press-fitting through a pipe with a double nozzle inserted into the soil destruction, or conversely, if the gelation time is long, both A and B can be injected as -liquids. A one-shot method is also possible.

In this way, the chemical solution injected during soil demolition has a preset gel content. When 11 TIC is reached, the soil becomes hydrated and the soil particles in the area into which the chemical solution is injected are immobilized, imparting high unconfined compressive strength to the soil fracture and liquid impermeability, thereby stabilizing the soil quality. It will be destroyed.

In the present invention, the gelation time of the chemical solution can be adjusted by increasing or decreasing the amount of the curing accelerator in the B solution, increasing or decreasing the amount of each component in the A solution, or adjusting the aqueous solution concentration in the drug solution. can be done easily.

(5) Effects of the Invention The soil stabilization method of the present invention includes liquids A and B as described in fItf.
The present invention is characterized by injecting the chemical solution obtained by mixing the two into the soil, making it easy to adjust the gelation time. This makes it possible to obtain soil with good water-stop properties and good unconfined compressive strength.

In addition, especially for soils with a mixture of fine-grained soil and coarse-grained soil,
If the method of the present invention is applied using the solution type B solution after applying the chemical solution for cement using the conventional method or the woodworking method, the gelled chemical solution will not dissolve again as in the conventional method, and the above-mentioned soil destruction will be reliably achieved. can be stabilized.

Example of tel implementation Examples and comparative examples of the present invention are shown below.

It simply refers to parts by weight or % by weight.

Example I No. 1 sodium silicate A based on JIS K 140'8
(Sin, content 35.55%, Nano content 17.
Add 20F of water to 80y (48%) to make a diluted sodium silicate aqueous solution, and separately add a sodium aluminate aqueous solution (AI, O, content 20%, NatO content 19%) 1
Water 5F was added to 5y to prepare a diluted sodium aluminate aqueous solution.

Next, the diluted sodium silicate aqueous solution and the diluted sodium aluminate aqueous solution were each stirred at high speed so that the weight ratio was 100:
Continuously add and mix aluminum = phosphorus and modified sodium silicate (rum aqueous solution (specific gravity L46)
I got it.

Mix the aluminum-modified sodium silicate and urine in the proportions listed in Table 1 to make 200 ml of a solution (liquid A), and add 2 ml of water.
00 ml was used as Solution B, and both solutions adjusted to 20° C. were added together in a volume ratio of 1=1, and the gelation time was as shown in Table 1. In liquid A, the concentration was about 24%, the molar ratio of silicon dioxide to sodium oxide was 17, and the molar ratio of aluminum to silicon dioxide was F1a06 when converted to aluminum oxide.

Then, add 100 parts of the mixed chemical solution of the above A% B solution to Toyoura standard sand 25
It was infiltrated into 0 parts and tamped and hardened so that the porosity became 40%. After curing the cured product for 3 days in wet sand, the unconfined compressive strength was measured and the results were as shown in Table 2.

On the other hand, 100ml of the mixed chemical solution of solutions A and B was taken, gelled in a glass beaker, sealed and cured for 3 days, and the amount of syneresis water in the gelled product was measured. The results are shown in Table 2. Ta.

Furthermore, whether or not syneresis water was produced was measured by bringing the gelled product produced by the conventional suspension-type drug solution into contact with the gelled product produced by the mixed drug solution A and B described above.

First, add 50 liters of the main agent solution obtained by adding 25 g of water to IJ Kumu 25 (No. 3 silicic acid) in a 300 ml glass beaker, and add 20 ml of ordinary Bortland cement to 43 ml of water.
50 ml of the hardened side in which y was dispersed was added and mixed to form a gel (this gelled product is hereinafter referred to as LW homogel). Next, 100 liters of the above A%B liquid mixture was poured onto the LW homogel, gelled and sealed, and the amount of syneresis water in the gelled hindlimb was measured for 3 days.The results are shown in Table 2. Ta.

Example 2 For 100y of No. 1 sodium silicate used in Example 1,
A water dispersion table containing 8.5% aluminum hydroxide (AI(OH)s) was added and heated to prepare an aqueous solution of aluminum modified silicic acid (IJ cum) (specific weight: 50). Thereafter, solutions A and B listed in Table 1 were prepared in the same manner as in Example 1, and the gelation time and other properties of the mixed chemical solutions were measured. The results were as shown in Fi Tables 1 and 2.

Regarding Solution A, the concentration was about 32%, and the molar ratio of silicon dioxide to sodium oxide was z11, and the molar ratio of aluminum to silicon dioxide when converted to aluminum oxide was 03. However, for convenience, these values are based on AI (
ffH), 1 mol to A1. The component corresponding to O, is 1/
Calculated assuming that 2 moles are produced.9.

Examples 3 to 10 Add the amount of water listed in Table 1 to make 200we of liquid A, and add the amount of hardening accelerated cutting listed in Table 1 to 200mL.
Solution 1 was used as solution B, and solutions A and 8 were combined to obtain a drug solution. The mixing ratio Fi of both liquids in Example 3 was 1 volume of liquid A to 2 volumes of liquid B, and all other liquids were mixed in equal volumes. Thereafter, gelation time and other physical property values were measured in the same manner as in Example 1. The results are as shown in Table 1 and Table 4IIJz.

(Margin below) Table 1 *Add glyoxal syK water with a concentration of 4596 Table 2 Example 11 Soil stabilization was carried out as follows.

l) Preparation of chemical solution The aluminum modified sodium silicate aqueous solution prepared in Example 1 was used as solution A, and 200I! Dissolving mixer - Kll Add 12 kg of soda carbonate and an appropriate amount of water, stir and dissolve 2007
'The solution was designated as B solution.

2) The hole was drilled to a depth of approximately 7 m where injection was performed while running tap water from the tip of the drilling rod.

In addition, the ground permeability coefficient 1d 1 x 10-261II/
The soil quality was coarse sand with a mixture of fine sand.

3) Prepare two graft pumps that can change the injection speed, and
The 5-shot method allows liquid A to reach 10 I/min! As for liquid B, mixed chemical solution 2001 was injected at an injection rate of 15/min. The injection pressure at that time was Fi2-4. When the predetermined amount of injection was completed, the rod was stepped up by 1 frL, and 2001 was repeatedly injected in the same manner.

The gelation time when 1 volume of liquid A and 15 volumes of wave B were mixed was 1 minute and 30 seconds at a liquid temperature of 20°C.

4) Observation of the solidification state during excavation and physical property test of the solidified material The results of excavation to the injection depth and confirmation of the solidification state showed an ideal penetration and solidification state close to a circular shape.

The soil clods collected by excavation were placed in polyethylene bags, sealed, transported to a testing room, molded, and subjected to unconfined compressive strength and water permeability tests.The results were as follows.

Uniaxial compressive strength = 3.7 instant/- Water permeable system &: K15 == 7.3 x 10 x/
See Comparative Examples 1 and 2 100 d of water was added to 100 parts of JIS No. A sodium silicate to make AM, and sodium bicarbonate 9F1 42 potassium bicarbonate and 1' g of potassium carbonate (Comparative Example 1), 11 g of sodium bicarbonate and 45% Glyoxal 5y (Comparative Example 2
) to obtain a 200d B wave, and a large amount of liquid A and B.
The liquids were mixed in equal volumes, and the gelation time and other properties were measured in the same manner as in Example 1.

As shown in Table 3, the results showed that the amount of synergic water was large, and a part of the gelled drug solution that came into contact with the special KLW homoglue was redissolved, producing a large amount of synergic water.

Table 3

Claims (1)

[Claims] 1. Solution A: The molar ratio of silicon dioxide to sodium oxide is 1 to 28, and the molar ratio of aluminum to silicon dioxide when converted to aluminum oxide is 0.
An aluminum-modified aqueous sodium silicate solution having a concentration of about 20-50% by weight, with a concentration of 0.01-0.1%. Solution B: (1) Water-soluble inorganic acid or water-soluble inorganic salt (2)
Water-insoluble or poorly water-soluble divalent or higher metal salts (3) cement and (4) glyoxal, γ-butyllactone,
Water that may contain one or more curing accelerators selected from ethylene carbonate, acetate esters of polyhydric alcohols, or water-soluble organic acids. A soil stabilization method characterized by injecting into soil a chemical solution obtained by mixing the above-mentioned solutions A and B. 2. The stabilization method according to item 1, wherein the water-soluble inorganic salt is a normal salt of an alkali metal, an acidic salt, or a normal salt of an alkaline earth metal. 3. The stabilization method according to item 1, wherein the water-insoluble or poorly water-soluble salt of a divalent or higher metal is calcium sulfate, calcium hydroxide, or calcium carbonate. 4. The stabilization method according to item 1, wherein the cement is Boltland cement. 5. The stabilization method according to item 1, wherein the water-soluble organic acid is acetic acid, citric acid, lactic acid, or tartaric acid.