JP3142325B2 - 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 agent using a mixture of aqueous colloidal silica and an aqueous solution of sodium silicate having a high molar ratio as a base material, and a method for injection of the same.

[0002]

2. Description of the Related Art Conventionally, in tunnel works and urban civil works, various grouting agents are used for strengthening soft ground and stopping spring water in accordance with 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. Of these, the former suspended grout is a curing agent (gelling agent)
Is a drug using hardly soluble calcium salts such as Portland cement, slaked lime, steel slag, etc., and the latter solution-type grouting agents include, for example, various acids such as sodium hydrogen sulfate, magnesium sulfate, phosphoric acid, acetic acid, glyoxal, ethylene carbonate and the like. And soluble acid compounds such as organic acids, aldehydes and esters.

[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 a 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. Sho 63)
JP-A-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).
Or a trivalent metal salt such as an aluminum salt (JP-A-59
A method of adding a suspended or solution electrolyte as in the case of the water glass system and curing the same has been proposed.

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 described in many documents. The problem of environmental pollution that causes the contamination of groundwater and the corrosion of underground buried objects due to the coming alkaline salts. When using acidic water glass, the above-mentioned alkali problem can be directly avoided, but the 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. However, suspension-type grouting agents such as Portland cement have a tendency to have a high strength over time. On the other hand, the cement particles cannot be injected deeply into the ground depending on the geology of the ground in many cases. However, 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. However, the homogel is usually much stronger than a water-glass type. weak. 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, for practical use of a colloidal silica-based solution-type grouting agent, improvement in strength as well as cost reduction is an important issue. 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, the above-mentioned colloidal silica is different from a normal product in which the molar ratio is in the range of 50 to 100, and is rather close 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, when a mixture of ordinary colloidal silica and high molar ratio sodium silicate is in a specific composition region, it is suitable as a ground injection agent. It has been found that it exhibits self-hardening properties.

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 does not contain a cement component used for strengthening soft ground and stopping groundwater from flowing out. An object of the present invention is to provide an injection method for injecting the ground injection agent into the ground.

[0010]

In order to achieve the above object, a ground injection agent according to the present invention comprises aqueous colloidal silica having a molar ratio of at least 40 represented by SiO ₂ / Na ₂ O and Si.
A mixed solution of an aqueous solution of sodium silicate having a molar ratio represented by O ₂ / Na ₂ O of 3.5 or more, wherein SiO _{2 of} the mixed solution is
/ Na ₂ O is a molar ratio of 7.5 to 19,
_{(2) The} constitution is characterized in that the concentration is 15 to 35% by weight.

Further, the second ground injection agent according to the present invention is characterized by a composition comprising the above mixture and at least one selected from glyoxal, gamma-butyrolactone, ethylene glycol diacetate and ethylene carbonate.

The aqueous colloidal silica used in the present invention is a known one usually referred to as silica sol. For example, water glass is used as a raw material in an ion exchange method, an acid neutralization method, an electrodialysis method, or a peptization method of silica gel. Manufactured. 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. 52-33899, U.S. Pat. No. 1-317115. In addition, for example, U.S. Pat.
Production method by oxidation of metal silicon described in 7367,
Colloidal silica obtained by a method of dispersing fine silica powder in water described in U.S. Pat. No. 2,951,044 or JP-A-62-127216 can be used.

These aqueous colloidal silicas may have a mean particle size of 3 to 100 nm, but those having a large particle size have a weak homogel strength and, in many cases, have an average particle size of 50 nm or less. Particles are practical. The commercially available standard grade of such colloidal silica has an average particle size of 10
Although it is about 20 nm, for the purpose of the present invention, those having a small particle grade of 3 to 10 nm have high gel strength and are particularly preferable. But,
Particles having an average particle diameter of 3 nm or less contain a large amount of an alkali component for the purpose of stabilization, and thus are not suitable for the purpose of the present invention.

In any case, the aqueous colloidal silica contains a small amount of alkali ions or hydrogen ions as a colloid stabilizer, but in the present invention, the alkali content is represented by SiO ₂ / Na ₂ O. The molar ratio (hereinafter referred to as “molar ratio”) is 40 or more, preferably 45 to 500.
Aqueous colloidal silica is selectively used. The component composition, the content of SiO ₂ is 15～50Wt%, preferably good ones around 30 wt%, for example those described in Table 1 can be mentioned typically.

[0015]

[Table 1]

The high molar ratio sodium silicate to be added to the above aqueous colloidal silica has a molar ratio of 3.5 or more, especially 3.9 to 5 and a low alkali content and a high solid content (SiO ₂ + Na ₂ O). Sodium silicate solutions are advantageously used. Examples of such sodium silicate include, for example, commercially available products shown in Table 2.

[0017]

[Table 2]

The ground injection agent according to the present invention is a mixed solution of the above-mentioned aqueous colloidal silica and a high molar ratio sodium silicate aqueous solution. The composition of the mixed solution varies depending on the properties of the ground to be treated and the injection method. molar ratio is from 7.5 to 19, preferably 8 to 18, and 15 to 35 wt% as SiO ₂ concentration, preferably the requirement to be in the range of 20 to 30 wt%. It is surprising that if both components are mixed in such a ratio as to have such a composition, the solution itself will cause gelation with a practically usable homogel strength without necessarily requiring another curing agent.

In the above composition, when the molar ratio is less than 7.5, a gel is generated at the time of mixing and the gel time is shortened in the range of 5.7 to 7.4, and the gel time is shortened. Inevitably, practical strength cannot be obtained. When the molar ratio is further reduced, 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 19, only the characteristics of colloidal silica can be obtained, and the expected effect cannot be obtained.

When sodium silicate mixed with colloidal silica has a low molar ratio such as JIS No. 3 sodium silicate, an inconvenient phenomenon such as instant gelation occurs when a large amount is mixed. Can only mix a small amount.

A mixture of the aqueous colloidal silica and the aqueous solution of sodium silicate having a high molar ratio may be mixed with a curing agent, a curing accelerator, and the like to form a ground injection agent having a different composition.

As the curing agent to be blended, for example, one or more selected from glyoxal, gamma-butyrolactone, ethylene glycol diacetate and ethylene carbonate are preferably used. It may be injected separately with the chemical solution of the hardener injection agent, or may be injected after mixing. Examples of the curing accelerator include one or more selected from acids such as carbonic acid, acetic acid, sulfuric acid, phosphoric acid, sulfurous acid, hydrochloric acid, and nitric acid, and soluble alkaline earth metal salts thereof.

The selection and mixing ratio of the curing agent and the curing accelerator are appropriately set in consideration of the properties of the ground, construction purpose, economy, construction conditions, and the like, thereby adjusting the gel time and improving the strength. Can be. For example, if glyoxal is used alone, the gel time is long, but it is a strong injectable. However, when used in combination with phosphoric acid or sulfuric acid, the gel time can be shortened, and the gel time can be appropriately adjusted at a desired strength.

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 system and a two-liquid system.
Injection is performed in two shots using a 5-shot system and a two-liquid two-system system. As an injection method utilizing the characteristics of the curing agent, a one-shot method is preferable.

[0025]

The ground injection agent according to the present invention comprises the specified SiO.
Excellent self-hardening is achieved only by blending aqueous colloidal silica having a molar ratio of ₂ and Na ₂ O and a high molar ratio sodium silicate so that the molar ratio and the SiO ₂ concentration are within a specific range. Hardens with practical compressive strength. Further, when a curing agent and a curing accelerator are added to this, it is converted into a homogel having high uniaxial compressive strength. Therefore,
When injected into the ground, an extremely strong strengthening action and water stopping function are exhibited.

[0026]

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

Examples 1 to 10 and Comparative Examples 1 to 3 Various colloidal silicas shown in Table 1 and sodium silicate shown in Table 2 were prepared according to the mixing ratios shown in Table 3 to prepare various ground injection agents. 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 a high molar ratio sodium silicate solution exhibited excellent self-hardening properties, and practical compressive strength was recognized in a wide gel time.

[0030]

[Table 3]

[0031]

[Table 4]

Examples 11 to 12 A mixture (solution A) of 60 ml of colloidal silica (A-1) shown in Table 1 and 40 ml of 4.7 mol sodium silicate shown in Table 2 and 40 watts
A curing agent (solution B) was prepared by diluting 20 ml of a t% glyoxal aqueous solution with 80 ml of water. In the case of using only the solution A (Example 11), a homogel of the ground injection agent was prepared from a mixed solution of the solution A and the solution B, and the characteristics were evaluated. The results are shown in Table 5 in comparison with the composition of the solution A.

[0033]

[Table 5]

Examples 13 to 18 and Comparative Examples 4 to 7 A mixture of colloidal silica shown in Table 1 and sodium silicate shown in Table 2 (solution A) was mixed with a curing agent and the like (solution B) at the ratio shown in Table 6. A homogel was prepared for the ground injection. Table 7 shows the obtained evaluation characteristics in comparison with the composition of the solution A.

[0035]

[Table 6] Table Notes: 1) B-1 is glyoxal (40% aqueous solution), B-
2 is gamma-butyrolactone, B-3 is ethylene glycol diacetate, and B-4 is ethylene carbonate (30% aqueous solution). The same applies hereinafter. 2) No. 3 sodium silicate used.

[0036]

[Table 7]

Examples 19 to 23, Comparative Example 8 Colloidal silica (A-1, A-3) shown in Table 1 and Table 2
A homogel was prepared for a ground injection agent composed of a mixture (solution A) and a curing agent (solution B) having the composition shown in Table 8 using 3.95 mol sodium silicate. The evaluation characteristics of the obtained cured product are shown in Table 9 in comparison with the composition of Liquid A.

[0038]

[Table 8]

[0039]

[Table 9]

[0040] Example 24, Comparative Examples 9-11 Colloidal silica as A-2 and alkaline intensive commercial products shown in Table 1 _{[SiO 2: 20.1wt%, Na 2} O: 4.
0 wt%, "Cataloid Sl-500" manufactured by Kasei Kasei Co., Ltd.]
(Referred to as A-4), and A liquid and B
A ground injection agent composed of a liquid was prepared. The evaluation characteristics measured for the homogel were compared with the composition of the solution A, as shown in Table 11.
It was shown to.

[0041]

[Table 10]

[0042]

[Table 11]

The results in Table 11 show that the ground injection agent according to the present invention has stable durability over time.

Example 25 The soil injection agent of Example 24 was injected into soil by the following one-shot injection method. Solution A was prepared by mixing 3.95 mol sodium silicate with 4.5 l while stirring 10.5 l of colloidal silica (A-2).
Prepared by adding mixing procedure. Solution B is B-1 in 13.5 l of water.
(40% aqueous glyoxal solution) 1.5 l and 75% phosphoric acid 22
5 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.

Using a plunger type pump (trade name Chemide Pump 1 AN-P32S6-37S, manufactured by 1WAKI CO., LTD) on sandy soil having a permeability of 8.35 × 10 ⁻³ cm / sec.
30 l was injected at 1.5 l / min. The soil injection was performed at an injection pressure of ² kg / cm ² , without any problems during the injection stage.
The modified soil one day old after injection is 5.6 × 10 ^-7 cm / s in permeability
ec, 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.

[0046]

As described above, according to the present invention, a mixture of aqueous colloidal silica and an aqueous solution of sodium silicate having a high molar ratio is used as a main agent, and has high practicability effective for strengthening soft ground, stopping spring water from flowing out, and the like. It is possible to provide a ground injection agent and an injection method thereof.

──────────────────────────────────────────────────続 き Continued on the front page (72) Eiji Miyoshi Inventor, Civil Engineering & Construction Materials Research Laboratories, Research & Development Division, Koto-ku, Tokyo, Japan (72) Inventor Shigeru Sonobe, Kameido, Koto-ku, Tokyo No. 9-15-1 Japan Chemical Industry Co., Ltd. Research and Development Headquarters Civil Engineering Construction Materials Research Laboratory (56) References JP-A-57-172583 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) C09K 17/12 C09K 17/02 E02D 3/12 101

Claims (2)

(57) [Claims] 1. The molar ratio represented by SiO ₂ / Na ₂ O is as follows:
More than 40 aqueous colloidal silica and SiO ₂ / Na ₂ O
A mixed solution of an aqueous sodium silicate solution having a molar ratio of 3.5 or more, wherein the molar ratio of the mixed solution expressed by SiO ₂ / Na ₂ O is 7.5 to 19, and the SiO ₂ concentration is 15 to 35% by weight. % Ground injection agent. 2. A method for injecting a ground injection agent according to claim 1, wherein the ground injection agent is injected into the ground by one of a one-shot method, a 1.5-shot method and a two-shot method.