JP3150380B2 - Ground injection agent and its injection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground injection using a mixed solution of aqueous colloidal silica and an aqueous solution of potassium silicate having a high molar ratio as a base material, and a method for injecting the same.

[0002]

2. Description of the Related Art Conventionally, various kinds of grouting agents have been used for the strength of soft ground and for stopping spring water in tunnel construction and urban civil engineering work according to the properties of the ground. As this kind of grouting agent, a water glass (alkali silicate aqueous solution) -based grouting agent is frequently used in terms of cost and function, and there are a suspension type (LW) and a solution type. Among them, the former grouting agent is a chemical using hardly soluble calcium salts such as Portland cement, slaked lime, steel slag, etc. as a hardening agent (gelling agent), and the latter solution type grouting agent is, for example, sodium hydrogen sulfate, magnesium sulfate. And various acids such as phosphoric acid, acetic acid, glyoxal, and ethylene carbonate; and soluble acidic compounds such as aldehydes and esters as curing agents.

[0003] Recently, an injectant mainly containing acidic water glass or aqueous colloidal silica, which dislikes the alkali of water glass, has been developed. For example, in the case of an aqueous colloidal silica grouting agent, as a hardening agent, cement such as slaked lime or Portland cement (Japanese Patent Application No. 59-66482), or an alkaline earth metal salt such as magnesium sulfamate (Japanese Unexamined Patent Publication No. 168485), alkali metal salts such as sodium chloride and sodium hydrogen sulfate (JP-A-59-152985), and organic drugs such as glyoxal (JP-B-2-36156).
JP-A-59-152984, etc., and a method of curing by adding a suspension or solution electrolyte as in the case of the water glass system.

In the method using water glass, a large amount of sodium salt contained in the injected material impairs the durability of the ground after injecting the chemical and further elutes, as has been introduced in many documents. Environmental pollution that causes the contamination of groundwater and the corrosion of underground buried objects due to the coming alkaline salts has become a problem. Although the above-mentioned alkali problem can be directly avoided when acidic water glass is used, these essential disadvantages are exactly the same.

For this reason, the use of colloidal silica-based grouting agents substantially free of alkali metal salts has recently attracted attention. While an increase in strength can be expected, cement particles often cannot be injected and penetrated deep into the ground depending on the geology of the ground, and such a ground still requires a liquid hardener.

In general, colloidal silica loses fluidity and changes to a gel-like solid when a polyvalent metal ion or an acidic substance is used as a curing agent, but the homogel generally has a much higher strength than a water glass-based one. Weak to. In addition, since this gel does not increase in strength over time, it cannot be expected to have durability against running water and ground fluctuation. Usually, at least 0.3 kg / cm ² in the case of the purpose of temporary water stopping of the ground, there is a preferably requires 0.4 kg / cm ² or more Homogeru strength. Therefore, in order to put the colloidal silica-based solution type grout agent into practical use, it is important to improve the strength together with the cost reduction effort. In this regard, Japanese Patent Publication No. 2-36156 uses colloidal silica having a high Na ₂ O concentration of 0.6 to 5% by weight.
A homogel strength of 1 kg / cm ² or more was obtained using colloidal silica having a molar ratio of ₂ / Na ₂ O of 4.7 to 5.4.

[0007]

However, such a colloidal silica is different from a normal product in which the molar ratio is in the range of 50 to 100, and has a property closer to water glass. No functional differences can be found compared to the high molar ratio water-based filler.

The inventors of the present invention have conducted intensive studies in view of the above facts. As a result, it has been found that when a normal mixed solution of colloidal silica and potassium silicate is in a specific composition region, self-hardening properties suitable as a ground injection agent are exhibited. Was found.

The present invention has been developed on the basis of the above findings, and has as its object to provide a colloidal silica-based ground injection agent which has a remarkable effect on strengthening soft ground and stopping water flowing out of groundwater. It is an object of the present invention to provide an injection method for injecting an injection into the ground.

[0010]

The ground injection agent according to the present invention for achieving the above object is a mixture of aqueous colloidal silica and an aqueous solution of potassium silicate.
When the molar ratio represented by O ₂ / (Na ₂ O + K ₂ O) is 5 to 20
The composition is characterized by having a self-hardening property at a SiO ₂ concentration of 13 to 35% by weight.

[0011] The ground injection agent according to the present invention is characterized by having a composition comprising a mixture of the mixture and an organic curing agent and / or an inorganic curing agent. Furthermore, the present invention is a chemical solution injection method for injecting into the ground to be treated using the above-described soil injection agent.

Hereinafter, the present invention will be described in detail. The aqueous colloidal silica used in the present invention is a known one usually referred to as silica sol, and is produced, for example, by using water glass as a raw material by an ion exchange method, an acid neutralization method, an electrodialysis method, or a peptization method of silica gel. Is done. Details of this production method are described in, for example, U.S. Pat.No. 2,577,484, U.S. Pat.No. 3,711,419, U.S. Pat.No. 2,572,578, Japanese Patent Application No. 52-3389.
No. 9, U.S. Pat.No. 3,668,888, JP-A-1-31
No. 7115, etc. In addition, for example, a production method by oxidizing metallic silicon described in U.S. Pat. Colloidal silica obtained by a production method by water dispersion of powder can be used.

These aqueous colloidal silicas may have a mean particle size in the range of 3 to 100 nm. However, those having a large particle size have a weak homogel strength. It is practical. The commercially available standard grade of such colloidal silica has an average diameter of 10 to 20 nm, but for the purpose of the present invention, a small particle grade of 3 to 10 nm is particularly preferred because of its high gel strength. However, those having an average particle diameter of 3 nm or less are not suitable for the purpose of the present invention since they contain an alkali component in an amount for stability.

In any case, the aqueous colloidal silica contains a trace amount of alkali ions or hydrogen ions as a colloid stabilizing agent, but in the present invention, the alkali content is a SiO ₂ / Na ₂ O molar ratio (hereinafter referred to as “a”). Aqueous colloidal silica having a molar ratio of 20 or more, preferably 30 to 500, is selectively used. As the component composition,
The content of SiO ₂ is preferably 15 to 50% by weight, and more preferably 20 to 35% by weight. For example, those described in Table 1 are representative.

[0015]

[Table 1]

The potassium silicate to be added to the above aqueous colloidal silica has a low alkali content and a solid content (Si
It is advantageous to use an aqueous solution of potassium silicate rich in O ₂ + K ₂ O). As such potassium silicate, for example, there are commercially available products listed in Table 2.

[0017]

[Table 2]

[0018] According to the present invention ground infusate is a mixture of the aqueous colloidal silica and potassium silicate solution, although the composition of the mixture varies depending on properties and grouting of the ground to be treated, the mixture SiO ₂ / (Na ₂ O + K ₂ O)
The molar ratio represented by 5-20, preferably 6-18,
And a SiO ₂ concentration of 13 to 35% by weight, preferably 20 to
The requirement is that it be in the range of 30% by weight. It is surprising that when both components are mixed at such a ratio as to have such a composition, gelling with a homogel strength that is practical for the solution itself occurs without necessarily requiring another curing agent.

In the above composition, when the molar ratio is less than 5, gel is generated at the time of mixing, the gel time is shortened, and practical strength cannot be obtained. Further, when the molar ratio is small, the function becomes the same as that of the water glass, and the characteristics using colloidal silica cannot be utilized.
On the other hand, if the molar ratio exceeds 20, only the characteristics of colloidal silica can be obtained, and the expected effect cannot be obtained.

The above-mentioned mixture of the aqueous colloidal silica and the aqueous solution of potassium silicate may be mixed with a curing agent or the like to form a ground injection agent having a different composition.

As the organic curing agent to be blended, for example, at least one selected from glyoxal, γ-butyrolactone, ethylene glycol diacetate and ethylene carbonate is preferably used. Further, as the inorganic curing agent, for example, carbonic acid, acetic acid, sulfuric acid, phosphoric acid, sulfurous acid, hydrochloric acid,
One or more selected from acids such as nitric acid and soluble salts thereof are preferably used.

The type and blending ratio of these curing agents may be selected according to the purpose of construction, economy, construction conditions, etc.
There is no particular limitation. For example, in the case of glyoxal, if it is used alone, it becomes a high-strength injectable with a long gel time, but is economically disadvantageous. Also, for example,
When a combination of a phosphoric acid and a magnesium salt with a polyphosphate or a combination of a phosphoric acid or an aluminum salt with a polyphosphate is used, a ground injection agent having improved strength can be obtained. These curing agents can be used as a mixture, and in this case, the gel time and strength can be adjusted more appropriately.

According to the injection method of the present invention using the above-mentioned ground injection agent, the two liquids are mixed according to the gel time, and the mixture is injected in a one-liquid one-system method and in a two-liquid one-system method.
Injection is performed in a 5-shot system or a two-liquid two-system system. The one-shot method is appropriate as an injection method utilizing the characteristics of the curing agent.

[0024]

The ground injection agent according to the present invention exhibits excellent self-hardening properties only by mixing aqueous colloidal silica and potassium silicate in a specific range of molar ratio and SiO ₂ concentration.
It cures with practical compressive strength in a wide gel time. When a curing agent is further added thereto, it is converted into a homogel having high uniaxial compressive strength. Therefore, when injected into the ground, an extremely strong reinforcing action and a water stopping function are exhibited.

[0025]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In each example, the evaluation of the ground injection agent was performed by the following measurement method.

Gel time: The viscosity is gradually increased when a ground injection agent mixed with components is put into a beaker and stirring is continued with a magnetic stirrer. At this time, the gel time is measured as the time from the point when the ground injection agent is put into the beaker to the point at which the viscosity increases and gels and the fluidity disappears even when the beaker is tilted by 90 degrees and the flow does not flow down.

Compressive strength: The ground injection agent before gelation, in which the components are uniformly mixed, flows into a mold of 50 mmφ × 100 mmH to be gelled, and the test specimen is cultivated in water and demolded after a predetermined time.
The uniaxial compressive strength of the homogel is measured using an arm slur type strength tester.

Examples 1 to 5 and Comparative Examples 1 to 5 Various types of ground injection agents were prepared by mixing the aqueous colloidal silica shown in Table 1 and potassium silicate shown in Table 2 in the proportions shown in Table 3. The gel time and the compressive strength of each injection were measured, and the results are shown in Table 4 in comparison with the composition of the mixture. From the results in Table 4, it was found that those composed only of a specific aqueous colloidal silica and potassium silicate solution exhibited excellent self-hardening properties and practical compressive strength in a wide gel time.

[0029]

[Table 3] Table Note: (* 1) SiO ₂ = 23 for high molar ratio sodium silicate
%, Na ₂ O = 6.0%, molar ratio 3.95.

[0030]

[Table 4]

Examples 6 to 13 and Comparative Examples 6 and 7 A mixture (solution A) of 50 ml of colloidal silica (A-1) shown in Table 1 and 3.1 mol A potassium silicate shown in Table 2 and an organic curing agent and inorganic A curing agent (solution B) was prepared by diluting the curing agent in water. A homogel of the ground injection agent was prepared from a mixed solution of the solution A and the solution B, and the characteristics thereof were evaluated. The composition is shown in Table 5, and the results are shown in Table 6 in comparison with the composition of the solution A.

[0032]

[Table 5] Table Note: (* 1) B-1 is glyoxal (40% aqueous solution), B-
2 is γ-butyrolactone, B-3 is ethylene glycol diacetate, B-4 is ethylene carbonate (30% aqueous solution), and so on. (* 2) Comparative Example 2 used No. 3 sodium silicate instead of potassium silicate

[0033]

[Table 6]

Examples 14-19 Homogel was prepared from a ground injection agent prepared by mixing a hardening agent (Solution B) in a mixture (Solution A) of a mixture of colloidal silica shown in Table 1 and potassium silicate shown in Table 2 at a ratio shown in Table 7. Created. Table 8 shows the obtained evaluation characteristics in comparison with the composition of the solution A.

[0035]

[Table 7]

[0036]

[Table 8]

Examples 20 to 28 and Comparative Examples 8 to 10 Ground containing a mixture of colloidal silica shown in Table 1 and potassium silicate shown in Table 2 (Solution A) and a curing agent (Solution B) in the ratio shown in Table 9 A homogel was prepared for each injection. Table 10 shows the obtained evaluation characteristics in comparison with the composition of the solution A.

[0038]

[Table 9]

[0039]

[Table 10]

Examples 29 to 34 A homogel was prepared from a ground injection agent obtained by mixing a hardening agent (Solution B) in a mixture (Solution A) of a mixture of colloidal silica shown in Table 1 and potassium silicate shown in Table 2 at a ratio shown in Table 11. Created. Table 12 shows the obtained evaluation characteristics in comparison with the composition of the solution A.

[0041]

[Table 11]

[0042]

[Table 12]

Example 35, Comparative Examples 11-12 As colloidal silica, A-1 shown in Table 1 and a commercial product having a large amount of alkali [SiO ₂ : 20.1 wt%, Na ₂ O: 4.
0 wt%, "Cataloid SI-500" manufactured by Kasei Kasei Co., Ltd.]
(A-4) Using No. 3 sodium silicate,
A ground pouring agent composed of the liquid A and the liquid B according to the formulation of No. 13 was prepared. The evaluation characteristics measured for the homogel were
The composition is shown in Table 14 in comparison with the composition of the liquid. The results in Table 14 show that the ground injection agent according to the present invention has stable durability over time.

[0044]

[Table 13]

[0045]

[Table 14]

Example 36 The soil injection agent of Example 35 was injected into soil by the following one-shot injection method. Solution A was stirred for 3.5 l of colloidal silica (A-1) while adding 3.5 mol A potassium silicate for 7.
Prepared with mixing procedure adding 5 l. Liquid B is added to 12.6 l of water with B-
2.3 l of 1 (40% aqueous glyoxal solution) and 75% phosphoric acid
180 g was added and sufficiently stirred to obtain a uniform liquid. One minute before the pouring operation, the liquid A was added while stirring the liquid A to prepare a ground injection agent.

A ground injection agent was injected into a sandy soil having a water permeability of 8.35 × 10 ⁻³ cm / sec at a rate of 10 l / min using a Dabcon pump [manufactured by Shimadzu Corporation] at a rate of 10 l / min. The soil injection was performed at an injection pressure of 5 kg / cm ² , but there was no problem at the injection stage. The modified soil one day after the injection has a permeability of 5.6 × 10 ^-7
cm / sec, and the compressive strength was 15 kg / cm ² (sand gel). From this result, it was confirmed that the present injectable composition sufficiently satisfies the performance even in practical use.

[0048]

As described above, according to the present invention, a highly practical ground injection agent which is mainly used for strengthening soft ground and stopping water discharged from ground water, mainly comprising a mixture of aqueous colloidal silica and an aqueous solution of potassium silicate. And its injection method can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09K 107: 00 (72) Inventor Eiji Miyoshi 9-15-1, Kameido, Koto-ku, Tokyo Japan Chemical Industry Co., Ltd. Inside the Materials Research Laboratory (72) Inventor Seibe Shigeru Sonobe 9-15-1, Kameido, Koto-ku, Tokyo Japan Chemical Industry Co., Ltd. Research and Development Headquarters Civil Engineering Materials Research Laboratory (58) Field surveyed (Int. Cl. ⁷ , DB name) C09K 17/02 C09K 17/12 C09K 17/42 C09K 17/48

Claims (5)

(57) [Claims] 1. A mixed solution of aqueous colloidal silica and an aqueous solution of potassium silicate, wherein the mixed solution is SiO ₂ / (Na ₂ O).
+ K ₂ O) is 5 to 20, and SiO ₂
A ground injection agent having a concentration of 13 to 35% by weight and having self-hardening property. 2. A ground injection agent comprising the mixture of claim 1 and one or more curing agents selected from glyoxal, γ-butyrolactone, ethylene glycol diacetate and ethylene carbonate. 3. Ground injection wherein the mixture of claim 1 is mixed with one or more hardening agents selected from acids or salts thereof such as carbonic acid, acetic acid, sulfuric acid, phosphoric acid, sulfurous acid, hydrochloric acid, and nitric acid. Agent. 4. A ground injection agent obtained by combining the mixed solution of claim 1 with the ground injection agent of claim 2 or 3. 5. A ground injection agent according to claim 1, 2, 3 or 4, which is injected into the ground to be processed by one of a one-shot method, a 1.5-shot method and a two-shot method. And chemical injection method.