KR100397249B1 - Ground material for pouring ground and ground pouring working method using the same - Google Patents

Abstract

In the ground injection grout and the ground injection method using the same, even when contacted with soil in the ground, it does not shorten the gelation time, exhibits high permeability by maintaining a long period of time, and it is easy to adjust the gelation time in the soil. For this reason, the ground injection grout applied to the improvement of large-capacity grounds, such as the prevention of ground liquefaction construction, is obtained.

Water glass and phosphoric acid are contained as an active ingredient, and the following conditions (1), (2) and (3), that is, (1) molar ratio (n) of water glass is 3.6 to 5.0, and (2) SiO ₂ concentration is 3 (%) <SiO ₂ (%) <1.7n (%), (3) The liquidity satisfies acidity to neutrality at the same time, and from the group of water glass, phosphoric acid, soluble polyvalent metal salt, alkali metal chloride and sulfamic acid It contains one or more selected species as an active ingredient, and the following conditions (1), (2) and (3), that is, (1) molar ratio (n) of water glass is 3.6 to 5.0, (2) SiO ₂ The concentration is 3 (%) <SiO ₂ (%) <10.0 (%), and (3) the liquidity is configured to satisfy acidic to neutrality at the same time.

As the ground injection method, the pure grout or the suspended grout is injected as the primary injection material, and then the grout material described above is injected as the secondary injection material.

Description

Ground injection grout material and ground injection method using same {GROUND MATERIAL FOR POURING GROUND AND GROUND POURING WORKING METHOD USING THE SAME}

The present invention does not significantly reduce the gelation time even when it comes into contact with soil in the soil, maintains it for a long time, exhibits high permeability, and makes it easy to adjust the gelation time in the soil. The present invention relates to a ground injection grout material suitable for the improvement of a large capacity ground and a ground injection method using the same.

As an injection grout material for preventing liquefaction of a fluidized ground due to the presence of groundwater, such as a slope or a large depth underground basement, the gelation time is generally long so that the injection material is evenly spread over a wide range. It is preferable to reduce the shortening of the gelation time in the soil to show high permeability, to be solid, and to be as close to neutral as possible as solid.

As a grout material having a long gelling time of this kind, a solution-type water glass-based grout using a non-alkaline silica sol has been developed.

However, the solution-type water glass grout using this non-alkaline silica sol is in contact with the soil during the infiltration into the ground, and the pH value is shifted from acidic to neutral. Therefore, the gelation time in the soil is significantly shortened. As a preventive grout, a wide injection range cannot be obtained and is not suitable.

Therefore, the object of the present invention is that the gelation time cannot be significantly shortened even when it comes into contact with soil in the soil, and it exhibits high permeability by maintaining a long time, and thus exists in the above-mentioned known technique effective as a grout for preventing liquefaction of the ground. The present invention provides a ground injection grout material and a ground injection method using the same.

BRIEF DESCRIPTION OF THE DRAWINGS The graph of the correlation of the pH of the water glass-lactic-acid non-alkaline silica sol with the gelation time of homogel and sand gel (standard sand of Toyoura, Japan and sea sand of Chiba Prefecture).

Fig. 2 is a graph of the correlation between the pH of a water-glass-phosphate non-alkaline silica sol and the gelation time of homogels and sand gels (standard sand from Toyoura, Japan and sea sand from Chiba Prefecture).

3 is a schematic diagram of a laboratory injection test apparatus.

(Explanation of symbols for the main parts of the drawing)

1. Compressor 2, 3. Pressure gauge 4. Agitator

5. Water tank 6. Filling material 7. Acrylic pipe

8. Japan's Toyoura area standard sand 9, 10. Switching cock

11, 12. Wire mesh 13. Mess cylinder

In order to achieve the above object, according to the present invention, water glass and phosphoric acid are contained as an active ingredient, and the following conditions (1), (2) and (3), that is,

(1) The molar ratio (n) of the water glass is 3. 6 to 5.0,

(2) SiO ₂ concentration is 3 (%) <SiO ₂ (%) <1.7 n (%),

(3) the liquidity is acid to neutral,

It is characterized by satisfying at the same time.

In addition, in order to achieve the above object, according to the present invention, water glass, phosphoric acid, one or more selected from the group of soluble polyvalent metal salts, alkali metal chlorides and sulfamic acid as an active ingredient, Condition (1), (2) and (3), i.e.

(1) The molar ratio (n) of the water glass is 3. 6 to 5.0,

(2) SiO ₂ concentration is 3 (%) <SiO ₂ (%) <10.0 n (%),

(3) the liquidity is acid to neutral,

It is characterized by satisfying at the same time.

Further, in order to achieve the above object, according to the present invention, after filling the sparse part of the ground by injecting a pure grout or suspended grout as a primary injection material in the ground, the above-described ground injection grout as a secondary injection material It is characterized by injecting ash.

(Example)

Hereinafter, the present invention will be described in detail.

In general civil engineering, when the injection interval is 1m and the charge area per unit is 1m ² , the injection rate is 0.35 and the injection amount is (1 × 1 × 0.5) × 0.35 = 1751 at about 0.5m per stage. If the injection rate is 101 / min, the injection time requires 17.5 minutes.

Therefore, the required gelation time in the soil is about 17-20 minutes long.

On the other hand, the Soil Improvement of large soil by preventing liquefaction, injection interval 4m, when the charge of the area of 1 per 4 × 4 = to 16m ^2, and referred to a long hold 2m around the first injection stage, the injection amount is (4 × 4 X2) x 0.35 (injection rate) = 11,2001, and 11,200 / 20 = 560 minutes = 9.3 hours even if the discharge amount per minute was increased to 201 / min.

Therefore, the required gelation time in the soil requires a long gelation time of 9 to 10 hours or longer injection time.

Of course, in the case of the sand gravel ground which deviated, it may be injected in a short gelation time of about 1 minute, but also the required gelation time is maintained, and the drastic reduction of the gelation time during the injection is sufficient to penetrate and widen. It is to inhibit the penetration and low pressure penetration injection.

In view of the above-described fact, the present invention requires a gelation time in the soil for a short time (about 1 minute) to 10 hours or more, thereby preventing shortening of the gelation time and effective in preventing ground liquefaction. In order to obtain a ground injection grout material and a ground injection method using the same, which enables the ground improvement of a large-scale soil, the present invention will be described in detail below.

1. Water glass-phosphate

A graph of the correlation between the pH of non-alkaline silica sol and the gelation time of homo gels and sand gels (standard sand from Toura, Japan and sea sand from Chiba Prefecture) is shown in FIG. A (tablet) system is shown in FIG.

The water glass concentration of FIGS. 1 and 2 is about 5% in terms of SiO ₂ content as an example.

In FIGS. 1 and 2, curves a and A show homogels, curves b and B show sand gels produced by standard sand in Toyoura, Japan, and curves c and C show sand gels produced by sea sand produced in Chiba Prefecture, Japan. It is.

Of course, in this case, the gelation time is shifted to the relatively short side when the water glass is rich and to the long side when the water glass is lean.

Therefore, in the case of lengthening the gelling time, the concentration of the water glass itself is dimmed.

Comparing the non-alkaline silica sol of FIG. 1 with the non-alkaline silica sol consisting of the water glass-phosphate system according to the present invention of FIG. 2, in the low pH region of the curves a and A of the homogel, the curve a is in the curve A. In comparison, the gelation time is very long, but in contrast to the increase in pH, the curve A has a longer gelation time than the curve a.

In other words, the curve A has a much slower slope than the curve a.

This fact is believed to be due to the fact that phosphoric acid has a very small transition constant compared to lactic acid and a buffering action by reaction with water glass.

In view of the water gelation time in question, the curve b in the case of the standard sand of the Toyoura region in Japan is significantly shortened compared to the curve a, and the curve c in the case of sea sand from Chiba Prefecture, Japan is remarkably shorter.

As such, in FIG. 2, the curve B is not always shorter than the curve A but is always inversely long.

In addition, it was found that the degree of shortening of the curve C was also very small and the gelation time in the soil could be kept long.

The slope of the curve is also gentle and it is possible to maintain considerable gelation time even at high pH.

This fact is believed to cause metal blockage in other soils of phosphoric acid transfer and buffering as described above, and to mask metals in soil.

As mentioned above, when phosphoric acid was used for manufacture of a non-alkaline silica sol, it turned out that the shortening of the gelation time in soil is remarkably reduced compared with the case of lactic acid.

This proved to be a remarkable phenomenon as a grout for liquefaction prevention.

Of course, in general, the thicker the concentration of the water glass, the shorter the gelation time and the slower the delay.

In order to maintain the gelation time applied for the prevention of liquefaction, the concentration of water glass, that is, SiO ₂ content and the kind of water glass, that is, the molar ratio of water glass is also involved.

As a kind of water glass, it turned out that the molar ratio of the high molar ratio of 3.6-5.0 is preferable.

On the other hand, water glass having a molar ratio of 5 or more is not currently used because of its cumbersome manufacturing and high cost.

In the present invention, the use of such a high molar ratio of water glass with a molar ratio of 3.6 to 5.0 is preferred for achieving the above object, and the amount of acid and the amount of the additive as the reactant may be small. Therefore, the amount of the reaction product is small and eluted from the gelate. There is also an effect such as a decrease in the amount of salt.

As the concentration of water glass, the lower limit of SiO ₂ (%) in the silica sol is 3% and the upper limit is 1.7 times the molar ratio (n) in relation to the molar ratio of the water glass used at that time in view of both gelation time and high grain strength. It was found to be desirable.

That is, the concentration range of the SiO ₂ (%) is preferably in the range of _{3 (%) <SiO 2 (} %) <1.7n (%).

n represents the molar ratio of water glass.

If it is 3% or less, the permeability is good, but there is a difficulty in the certainty of the solidification.

Moreover, it also falls remarkably even in high grain strength.

In addition, when it is 1.7n% or more, the gelation time is accelerated and difficulties in permeability and uniform solidification in the soil are found.

Therefore, it is preferable that this invention satisfy | fills each above conditions simultaneously.

2. Water Glass-Phosphate-Additive

In the above, it was proved that the water glass-phosphate system showed a phenomenon peculiar to gelation.

Here, if the gelation time can be adjusted, the strength of the solidified material can be increased, or the concentration of the water glass used can be increased, the effect of the prevention of liquefaction is further improved.

The inventors also note that the molar ratio of the water glass used for the silica sol made of water glass-phosphoric acid and the liquid soluble range of the silica sol are as described above, and the water-soluble polyvalent metal salt, alkali metal chloride, sulfamic acid It was found that the addition of the gelation can be controlled, the upper limit of the concentration of SiO ₂ (the concentration of water glass) can be increased to about 10%, the strength can be increased, and the like.

The water-soluble polyvalent metal salt reacts with phosphoric acid to form an acidic liquid as an insoluble double salt of the polyvalent metal and phosphoric acid.

This solution neutralizes the water glass and crosslinks the silica and precipitates the silica. At this time, it precipitates around the polyvalent metal phosphate suspended in the silica solution to form a sol. Finally, the insoluble phosphate polyvalent metal silicate It is believed to form a hardened product.

As a result, the strength is increased.

In addition, the majority of the injection material composition is less insoluble in the silica sol as an insoluble salt, thereby providing an injection chemical with a low environmental load.

Specific examples of the water-soluble polyvalent metal salt include aluminum salts such as aluminum chloride, polyaluminum chloride, aluminum lactate and alum, alkaline earth metal salts such as calcium chloride and magnesium chloride, iron salts such as iron chloride and iron lactate, and the like. .

Chlorides of alkali metals generally have the effect of promoting gelation time by the action of small amounts of alkali metal ions.

Therefore, it is effective in the case of producing a chastity effect, or when gelling time is very long and solidification takes time.

It also has an effect on high strength.

Specifically, sodium chloride and potassium chloride are adsorbed.

Sulfamic acid does not fluctuate gelation time even if a part of phosphoric acid is replaced, so that the use of phosphoric acid can be reduced by that much.

In addition, the strength of the solidified body can be slightly enhanced.

Substitution of a portion of phosphoric acid with lactic acid results in the effect of being close to the lactic acid system as a whole and slightly losing the properties of phosphoric acid.

On the other hand, in sulfamic acid, the tendency is very small, and the above effects are exhibited.

3. Crude phosphoric acid

The phosphoric acid used in the above 1 and 2 is usually industrially refined phosphoric acid, but instead, crude phosphoric acid before purification treatment is used.

There are a dry method and a wet method for the production of phosphoric acid. In either method, the crude phosphoric acid before purification treatment is used.

Crude acid usually contains some SO ₃ , Fe ₂ O ₃ , Al ₂ O ₃ , SiO ₂ , and the like as impurities.

Among these, iron is mainly present in the form of iron phosphate, and it is thought that the iron phosphate promotes the coagulation of the gel (colloid), resulting in a desirable effect.

4. Liquid

The liquidity as the ground injection grout material of the present invention is excellent in permeability due to the long gelling time in acidic acid, and in order to obtain a high strength solidification in pure blending, the pH can be used as a neutral region, that is, a pH of about 5 to 9 as neutral. have.

5. Ground injection method using the above-described ground injection grout material

The above-mentioned ground injection grout material of the present invention is used in the ground injection method involved in the composite injection.

That is, in the ground to be injected, first, suspended grout (such as gelling time within 30 seconds) of pure grout or cement is injected as the primary injection material.

The primary injection material in this case may be the grout material described above according to the present invention.

As a result, the loose portion of the ground is filled.

Therefore, the above-mentioned grout material concerning this invention is inject | poured as a secondary injection material in the above-mentioned primary injected ground.

In this case, in the conventional grout material as the secondary injection material, the gelation time is shortened due to the presence of the primary injection material. However, when the above-described grout material of the present invention is used as the secondary injection material, such injection does not occur and a wide range of injection is possible. Done.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

1. Material used

(1) water glass

The high molar ratio water glass and normal JIS3 water glass which consist of the composition shown in Table 1 were used.

TABLE 1

water glass Specific gravity (20 ℃) SiO ₂ (%) Na ₂ O (%) Molar ratio High Molar Ratio Glass 1.32 25.5 7.03 3.75 JIS No.3 Water Glass 1.39 29.2 9.5 3.17

(2) phosphoric acid

(a) purified phosphoric acid

75% Industrial Purified Phosphate Specific Gravity (20 ℃) 1.58

(b) crude phosphoric acid

Prepared phosphoric acid specific gravity (20 degreeC) = 1.65 of about 75% of phosphoric acid content in the yellowish brown before refinement in phosphoric acid production

(3) heritage

75% industrial heritage

(4) poly aluminum chloride

JIS Poly Aluminum Chloride

(5) Calcium chloride (dihydrate)

Top grade reagents

(6) sodium chloride

Top grade reagents

(7) sulfamic acid (HOSO ₂ NH ₂ )

Top grade reagents

(8) sand

As fine sand, we use sea sand of Chiba, Japan as standard sand of Japan, silt sand.

2. Measurement

(1) Sandgel uniaxial compressive strength

Sand gels made from standard sand in Toura, Japan were subjected to polyvinylidene sealed curing (20 ° C) for 7 days and 28 days, and measured according to the Soil Engineering Society's Standard Uniaxial Compression Test Method.

(2) gelation time

(a) Gelation time of homogel

It is measured by the inverting method at 20 degreeC.

(b) gelation time in soil

The time when the grout liquid was mixed with the sand and stopped at 20 ° C, the supernatant was discarded, and the bamboo skewer was removed from the sand was measured as the gelation time in the soil.

(c) pH

Measured as glass electrode pH total.

3. Example

(1) compounding test

The compounding example and comparative compounding example which concern on this invention are shown collectively in Table 2.

TABLE 2

Comparing the system (Comparative Examples No. 1 and 2) consisting of water glass-lactic acid with the same SiO ₂ concentration from Table 2 and the system (Examples No. 1 to 7) related to the present invention, homogeneous at the same pH The gelation time of the gel is much longer in the comparative example, but the gelation time in the soil is inversely much longer in the first half.

Compared to the case of crude phosphoric acid and purified phosphoric acid (Examples No. 6, 7 and Examples No. 2 and 3), the crude acid is slightly in the first half, but the gelation time is long and the strength is slightly high.

As described above, in the present invention, the gelation time can be adjusted from short to long time in the soil from pH to acid to neutral.

If the SiO ₂ concentration is lowered (Example No. 8), of course, the gelation time is long, but the strength decreases.

When the SiO ₂ concentration is 3% or less outside the scope of the present invention (Comparative Example No. 3), the strength is considerably lowered.

Conversely, when the SiO ₂ concentration is set to 1.7n (1.7 x 3.75 = 6.4)% or higher (Comparative Example No. 4), the gelation time is accelerated even at a low pH, and the strength does not increase by that much.

In Examples 9 to 13 to which the additive was added, the gelation time of the homogel is generally slightly shorter than that of Example No. 8 of the control additive-free additive, but the gelation time in the soil tends to be slightly longer.

It is clearly enhanced in strength.

However, Comparative Example No. When, as shown in 5, is made rich the water glass concentration of SiO ₂ of 10% or greater, and becomes the low pH gel time of the soil in faster, it is easier to occur the partial gelation.

In view of the above, when the grout formulated within the scope of the present invention is close to neutral at high pH, the gelation time in the soil becomes faster, and when the pH is lowered, it can be lengthened, and the gelation time in a wide range of soil can be adjusted.

In particular, at low pH, the gelation time can be maintained considerably in the soil, which is expected to improve the permeability.

(2) penetration test

As is apparent from the results of the above compounding test, the present invention is easy to adjust the gelation time in the soil, and in particular, it is possible to maintain the gelation time for a long time, and excellent permeability is expected. Penetration tests were performed using the apparatus.

In FIG. 3, the injection material 6 is filled in the water tank 5 provided with the stirrer 4 connected to the compressor 1 via the pressure gauges 2 and 3.

7 is an acrylic pipe with an internal diameter of 50 mm and a height of 1 m, of which the Toura area standard sand (hereinafter referred to as standard sand) (8) is divided into nine layers and each layer has a relative density of 60% by horizontal blow. Firm as firmly as possible.

Subsequently, the injection material 6 filled in the water tank 5 is press-fitted to the standard sand 8 of the pipe 7 by the injection pressure of the compressor 1 at 0.5 kgf / cm <^2> .

The injection material penetrated into the standard sand 8 and the penetration distance was observed.

In FIG. 3, 9 and 10 are switching cocks, 11 and 12 are wire meshes, and 13 is a measuring cylinder.

Representative injection materials used in the test and the test results are shown in Table 3.

TABLE 3

Penetration Test No Injection Result of injection TABLE 2 pH One Example NO.1 2.9 Good penetration of the overall length of the standard sand (8) 2 Example NO.2 3.5 Good penetration of the overall length of the standard sand (8) 3 Example NO.3 5.8 35-40 cm from the bottom of the standard sand (8) Penetrates to height 4 Example NO.7 5.8 30 to 35 cm from the bottom of the standard sand (8) Penetrates to height 5 Example NO.9 3.6 Good penetration of the overall length of the standard sand (8) 6 Example NO.13 3.8 Good penetration of the overall length of the standard sand (8) 7 Comparative Example NO.1 3.8 25-30 cm from the bottom of the standard sand (8) Penetrates to height 8 Comparative Example NO.2 2.9 75 to 85 cm from the bottom of the standard sand (8) Penetrates to height 9 Comparative Example NO.5 3.6 55-65 cm from the bottom of the standard sand (8) Penetrates to height

From the results in Table 3, in the examples of the present invention, if the pH is 4 or less, the pH sufficiently penetrates the entire field, but it is not seen as sufficient penetration in the water glass-lactic acid system (Test Nos. 7, 8).

As described below, the ground injection ground material according to the present invention has the following effects.

1. The shortening of the gelation time in the soil from lactic acid to neutral is small.

2. In the low pH range it is possible to maintain the gelation time in long soils.

3. It becomes easy to adjust the gelation time in soil from lactic acid to neutral.

4. From the above, it is suitable for the improvement of the large-capacity ground like liquefaction prevention construction work.

Claims (5)

Water glass and phosphoric acid are contained as an active ingredient, and the following conditions (1), (2) and (3), that is, (1) The molar ratio (n) of the water glass is 3.6 to 5.0, (2) SiO ₂ concentration is 3 (%) <SiO ₂ (%) <1.7 n (%), (3) the liquidity is acid to neutral, Ground injection grout material, characterized in that to meet at the same time. Water glass, phosphoric acid, soluble polyvalent metal salts, alkali metal chlorides and sulfamic acid as one or more selected from the group containing as an active ingredient, the following conditions (1), (2) and (3), that is, (1) The molar ratio (n) of the water glass is 3.6 to 5.0, (2) SiO ₂ concentration is 3 (%) <SiO ₂ (%) <10.0 (%), (3) the liquidity is acid to neutral, Ground injection grout material, characterized in that to meet at the same time. The method according to claim 1 or 2, A grout material for ground injection, characterized in that the phosphoric acid is crude phosphoric acid. Purity grout or suspended grout is injected into the ground to fill the coarse part of the ground, and then, as the second injection, water glass and phosphoric acid are contained as active ingredients, and the following conditions (1), (2) and (3), i.e. (1) The molar ratio (n) of the water glass is 3.6 to 5.0, (2) SiO ₂ concentration is 3 (%) <SiO ₂ (%) <1.7 n (%), (3) the liquidity is acid to neutral, Ground injection method, characterized in that to inject the ground injection grout material that meets the same. After filling the soil with pure grout or suspended grout as primary injection material, the secondary injection material contains water glass, phosphoric acid, soluble polyvalent metal salts, alkali metal chlorides and sulfamic acid. One or more selected species as an active ingredient, and the following conditions (1), (2), (3), that is, (1) The molar ratio (n) of the water glass is 3.6 to 5.0, (2) SiO ₂ concentration is 3 (%) <SiO ₂ (%) <10.0 (%), (3) the liquidity is acid to neutral, Ground injection method, characterized in that to inject the ground injection grout material that meets the same.