JP3131900B2 - Grout material for ground injection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a grout material which has a reduced gelling time and a high permeability even when it comes into contact with soil in the ground, and is therefore effective in preventing liquefaction of the ground. ground
Consolidation method .

[0002]

2. Description of the Related Art In recent years, with the development of landfills and the like, an injection material capable of preventing liquefaction of the ground has been desired. The injection material for preventing liquefaction of the ground must be an injection material that solidifies a vast area and suppresses the flow of groundwater. In general, such an injection material has excellent permeability so that the injection material spreads over a wide range, has a long gelation time, and after consolidation, the consolidation material has excellent durability. It is necessary to be.

[0003] As an injection material for preventing liquefaction, conventionally,
A solution type water glass grout using ultrafine silica or non-alkali silica sol has been developed.

[0004]

Among them, the solution-type water glass grout using ultrafine silica particles has a high viscosity with gelation, and has a poor permeability. It is extremely difficult to adjust the gel time.

[0005] In addition, a solution-type water glass grout using a non-alkali silica sol penetrates into the ground, and the pH value shifts from acidic to neutral due to contact with the soil.
The gelation time is significantly shortened in soil, and a grout for preventing liquefaction of the ground cannot be obtained over a wide injection range, which is not suitable.

Therefore, the inventors of the present invention shorten the gelation time of the injected material in the ground, not only because the pH value of the injected liquid shifts to neutral, but also exist in the ground. Metal ions, especially calcium ions, iron ions, aluminum ions, etc. react with the silica in the implant to form polyvalent metal salts and judge that gelation is promoted, and suppress the formation of these polyvalent metal salts. As a result, the present inventors have found that the shortening of the gelation time can be reduced, thereby completing the present invention.

[0007] An object of the present invention is to reduce the gelation time even when it comes into contact with the soil in the ground, and to have high permeability, which is effective for preventing liquefaction of the ground. It is an object of the present invention to provide a method for consolidating the ground, which ameliorates the disadvantages of the prior art.

[0008]

According to the present invention, there is provided, in accordance with the present invention, an activated silicic acid or colloidal silica obtained by treating water glass with a cation exchange resin, a sequestering agent and a phosphoric acid-based resin. Grout material containing either or both compounds as active ingredients
Sequestering agent in the grout material in the ground
Reacts with trace metals in soil to form insoluble metal salts
The grout material.
Phosphoric acid compounds in soil react with trace metals in soil
To form soluble phosphates to sequester trace metals,
Silica in grout and trace metals in soil by blocking action
Reaction with the ground material, whereby the grout material
Reduces gel time even when in contact with soil inside
Liquid, and solidifies the ground over a wide area.
It is characterized in that it is suitable for the prevention of the formation of a gas .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The active silicic acid used in the present invention is obtained by passing water glass through a cation exchange resin, treating it with water, removing sodium ions in the water glass, and shifting to an acidity of pH 2 to 4, Usually, it contains ₂ to 6% of SiO2.

The colloidal silica used in the present invention is obtained by mixing the activated silicic acid obtained as described above with an aqueous alkali solution such as an aqueous alkali metal solution or an aqueous alkali silicate solution, and subjecting the silica particles to heat treatment with stirring to reduce the silica particles. grown, then it gives et been by concentrating the silica concentration, the particle size of particle dispersion having a diameter of about 10 millimicrons.

The grout of the present invention contains the above-mentioned activated silicic acid or colloidal silica, one or both of a sequestering agent and a phosphoric acid-based compound as active ingredients. For the purpose of adjusting the gel time, an acid, an alkali, a salt or the like is appropriately contained.
Of course, the above-mentioned sequestering agents and phosphate compounds can be used alone or in combination of two or more.

Examples of the sequestering agent include ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, propylenediaminetetraacetic acid, bis (2-hydroxyphenylacetic acid) ethylenediamine, succinic acid , and the like. Examples thereof include salts, aliphatic oxycarboxylic acids, condensed phosphates and the like. As the aliphatic oxycarboxylic acid, tartaric acid, citric acid, gluconic acid, dihydroxyethylglycine, etc., and as the condensed phosphate, there are salts of polyphosphoric acid such as pyrophosphoric acid, triphosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid. Examples thereof include sodium pyrophosphate, sodium acid pyrophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, sodium hexametaphosphate, sodium acid hexametaphosphate, and potassium salts thereof.

Among these sequestering agents, in particular,
It is preferable to use one or more of citric acid and condensed phosphate from the viewpoint of economy, practicality, and the like.

[0015] Examples of the phosphate compounds mentioned above, be other than condensed phosphate described above, for example, normal phosphates, orthophosphates, an acidic phosphate and the like.

The grout material according to the present invention thus formed has a relatively low viscosity until immediately before gelation, and the gelation time in soil is less reduced. This means that the sequestering agent reacts with trace metals in the soil to form insoluble metal salts.
To block trace metals, and phosphate compounds
Reacts with trace metals in the water to form insoluble phosphate,
In the same manner, sequester trace metals, and
Reaction between the silica in the grout material and trace metals
It is presumed to be a significant suppression.

[0017]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

1. Materials used (1) Water glass JIS No. 3 water glass is used.

(2) Activated Silicate An aqueous solution of water glass is treated with a cation exchange resin to obtain a pH of 2.
7. Use activated silicic acid with a silicic acid (SiO ₂ ) concentration of about 4%.

(3) Colloidal silica After the active silicic acid is poured into alkaline water to adjust the pH to 9.5,
Heat and stir at 90 ° C. until the SiO ₂ content becomes 9.0%, and use colloidal silica having the following physical properties.

Specific gravity: 1.11, SiO ₂ : 9.0%, pH:
9.5, average particle size of silica: 12 mμ

(4) Sequestering agent The following is used. (A) ethylene diamine tetraacetic _{acid: C 10 H 16 N 2 O} 8 (b) Disodium ethylenediaminetetraacetate: C ₁₀ H _{14
N 2 Na 2 O 8 · 2H} 2 O (c) citric acid industrial chemicals

Embedded image (D) Condensed phosphate (a) Sodium hexametaphosphate (NaPO ₃ ) ₆ (a) Sodium pyrophosphate Na ₄ P ₂ O ₇ .10H ₂ O (c) Sodium acid pyrophosphate Na ₂ H ₂ P ₂ O ₇

(5) Phosphoric acid compound As the phosphoric acid compound other than the condensed phosphoric acid compound, phosphoric acid, disodium hydrogen phosphate, and sodium dihydrogen phosphate are used.

(A) phosphoric acid 75% industrial phosphoric acid H ₃ PO ₄ (b) disodium hydrogen phosphate Na ₂ HPO ₄ .12H ₂ O (c) sodium dihydrogen phosphate NaH ₂ PO ₄ .2H ₂ O

(6) Sulfuric acid 75% Industrial sulfuric acid H ₂ SO ₄

(7) Potassium Chloride Reagent Primary KCl

(8) Sodium hydrogen sulfate Reagent first grade NaHSO ₄

(9) Sodium hydroxide solution A first-class 10M sodium hydroxide solution of the reagent is used.

(10) Sand Toura sand is used as fine sand having the particle size distribution shown in FIG. 1, and sea sand from Chiba prefecture is used as silty sand. In FIG. 1, a is a curve of sea sand from Chiba Prefecture, and b is a curve of Toyoura sand.

2. Measuring method (1) Uniaxial compressive strength of sand gel Totoura sand and Santo gel made of sea sand from Chiba prefecture were sealed and cured at 20 ° C with polyvinylidene chloride (20 ° C).

(2) Gelation time (a) Gelation time of homogel Measured by a cup inverted method at 20 ° C.

(B) Gelling time in soil At 20 ° C., the grout solution was mixed with sand and allowed to stand still, the supernatant was discarded, a bamboo skewer was inserted into the sand and the sand was pulled out. Measurement.

(3) pH Measured with a glass electrode pH meter.

(4) Viscosity Measured with a B-type viscometer until the viscosity exceeds 100 cps.

(5) Reduction rate of gelation time in soil The ratio of the reduction of gelation time in soil to the gelation time of homogel was calculated and indicated by the following equation.

[0036]

Therefore, a negative value indicates that the gelation time is delayed in the soil.

3. Active silicic acid system 3-1 Active silicic acid-sequestering agent system (1) Active silicic acid-disodium ethylenediaminetetraacetate system In active silicic acid-disodium ethylenediaminetetraacetic acid system, pH, gelation time and gelation time reduction in soil are as follows. As shown in Table 1.

[0039]

[Table 1]

(2) Active Silicic Acid-Citric Acid System In the active silicic acid-citric acid system, the pH was adjusted with citric acid and sodium hydroxide solution. Table 2 shows the pH, the gelation time, and the reduction rate of the gelation time in soil at that time.

[0041]

[Table 2]

(3) Active Silicic Acid-Condensed Phosphate System The pH was adjusted using sodium pyrophosphate and sodium hexametaphosphate as the condensed phosphate. P at that time
Table 3 shows H, the gelation time, and the reduction rate of the gelation time in soil.

[0043]

[Table 3]

3-2 Active silicic acid-phosphoric acid compound system This is a system involving active silicic acid and a phosphoric acid compound other than condensed phosphate. Sodium dihydrogenate was used in combination. p
Table 4 shows H, the gelation time, and the reduction rate of the gelation time in soil.

[0045]

[Table 4]

3-3 Combined Use of Active Silicic Acid-Sequestering Agent and Phosphoric Acid Compound This is an example of a system in which activated silicic acid is used in combination of a sequestering agent and a phosphoric acid compound. Citric acid, sodium hexametaphosphate, disodium hydrogen phosphate, pH of a system using sodium hydroxide solution as a pH adjustment,
Table 5 shows the gelation time and the rate of reduction of the gelation time in soil.

[0047]

[Table 5]

3-4 Comparative Example As a comparative example to the above-mentioned present invention, a system comprising active silicic acid and a usual reactant other than a sequestering agent or a phosphoric acid-based compound, and water generally used conventionally. A system consisting of glass and a reactant was taken up.

(1) The pH of active silicic acid is adjusted with sulfuric acid and sodium hydroxide solution. Table 6 shows the pH, the gelation time, and the rate of reduction of the gelation time in soil.

[0050]

[Table 6]

(2) Water Glass-Sodium Bisulfate System The pH of water glass was adjusted with sodium hydrogen sulfate. Table 7 shows the pH, gelation time, and soil gelation time reduction rate in that case. Adjustment of the pH was very difficult and under careful control. The concentration of water glass is almost the same as that of activated silica.
The amount of iO ₂ was adjusted.

[0052]

[Table 7]

4. Colloidal silica system 4-1 Colloidal silica-sequestering agent system (1) Colloidal silica-ethylenediaminetetraacetic acid system The colloidal silica-ethylenediaminetetraacetic acid system was partially adjusted with sulfuric acid. Table 8 shows the pH, the gelation time, and the reduction ratio of the gelation time in soil.

[0054]

[Table 8]

(2) Colloidal Silica-Citric Acid Potassium chloride was used as a reactant for colloidal silica, and the pH was lowered with citric acid. Table 9 shows the pH, the gelation time, and the reduction rate of the gelation time in soil.

[0056]

[Table 9]

(3) Colloidal Silica-Condensed Phosphate System The pH was adjusted by using sodium acid pyrophosphate as a condensed phosphate in a system of colloidal silica and phosphoric acid. The pH, gelation time and soil gelation time reduction rate at that time are shown in the table.
Like ten.

[0058]

[Table 10]

4-2 Colloidal Silica-Phosphate Compound A common phosphoric acid as a phosphate compound other than the condensed phosphate was added to a system comprising colloidal silica and potassium chloride to adjust the pH. Table 11 shows the pH, the gelation time, and the rate of reduction of the soil gelation time.

[0060]

[Table 11]

4-3 Colloidal Silica-System Combining Plural Types of Sequestering Agent and Phosphate Compound Citric acid, phosphoric acid, Table 12 shows the pH, the gelation time, and the reduction rate of the gelation time in soil for the system using sodium hexametaphosphate in combination.

[0062]

[Table 12]

4-4 Comparative Example As a comparative example for the above-mentioned present invention, a system comprising colloidal silica and a usual reactant other than a sequestering agent or a phosphoric acid compound, and water conventionally used in general were used. A system consisting of glass and a reactant was taken up.

(1) Colloidal Silica-Sodium Hydrogen Sulfate System The pH, gelation time and soil gelation time shortening rate of a system in which colloidal silica is adjusted with sodium hydrogen sulfate are shown in Table 13.

[0065]

[Table 13]

(2) Water Glass-Sodium Bisulfate System The pH of water glass was adjusted with sodium hydrogen sulfate. In this case, the pH, the gelation time, and the rate of reduction of the gelation time in the soil are shown in Table 14. The adjustment of the pH was extremely difficult, and the adjustment was carried out to a precise one. The concentration of the water glass was made to be substantially the same amount of SiO ₂ and colloidal silica.

[0067]

[Table 14]

5. Discussion of the results (1) Gelling time in soil In order to facilitate comparison of the results of the above Examples and Comparative Examples, the gelling time in soil corresponding to each pH was plotted. In the case of Toyoura sand, FIG. 2 shows the result of activated silica and FIG. 3 shows the result of colloidal silica. In the case of sea sand produced in Chiba Prefecture, FIG. 4 shows the result using activated silica and FIG. 5 shows the result using colloidal silica.

In the figure, 印 indicates activated silicic acid or colloidal silica-ethylenediaminetetraacetic acid, □ indicates activated silicic acid or colloidal silica-citric acid, triangle indicates activated silicic acid or colloidal silica-condensed phosphate, inverted triangle indicates Is an activated silicic acid or colloidal silica-phosphoric acid compound (excluding condensed phosphate), and the double triangle is an active silicic acid or colloidal silica-sequestering agent and a combination of phosphoric acid-based compounds according to the present invention. The symbol ● represents the case of the active silicic acid-sulfuric acid-sodium hydroxide type or colloidal silica-sodium hydrogen sulfate type, and the symbol × represents the comparative example of the water glass-sodium hydrogen sulfate type.

Throughout, it can be seen that the area of the present invention has an extremely long gelling time in soil as compared with the comparative example (●, x mark). In the case of Toyoura sand and sea sand from Chiba prefecture, the gelation time is generally longer in the case of Toyoura sand in the low pH range, and the gelation time is about the same as the pH rises, or slightly more in the case of sea sand from Chiba prefecture. The gel time appears to be longer. However, in general, Toyoura sand and sea sand from Chiba prefecture show the same tendency of soil gelation time.

2 to 5, a close observation of the system according to the present invention shows that the active silicic acid or colloidal silica-citrate system indicated by □ and the active silicic acid or colloidal silica-condensed phosphate system indicated by triangles are used. Medium gel times generally tend to be slightly longer than in other systems.

(2) Reduction rate of soil gelation time Reduction rate of soil gelation time corresponding to each pH was plotted. In the case of Toyoura sand, FIG. 6 shows the result of activated silicic acid and FIG. 7 shows the result of colloidal silica. In the case of sea sand produced in Chiba Prefecture, FIG. 8 shows the result using activated silicic acid, and FIG. 9 shows the result using colloidal silica. The indications of ○, □, triangle, inverted triangle, double triangle and ●, × are the same as in the case of soil gelation time in FIGS.

A comparison between the regions of the present invention marked with ○, □, triangle, inverted triangle, and double triangle and the comparison control regions marked with ●, × indicates that:
At low pH, the reduction of soil gelation time is relatively large,
It has become smaller with the rise.

As described above, in the case of the present invention, the gelation time in the soil is conversely delayed at a high pH (the shortening rate% is a negative value).
Such a tendency is also observed, particularly in the case of activated silicic acid. Such a result is very favorable for preventing liquefaction.

As can be seen from the circles, triangles, inverted triangles, and double triangles of the present invention, in the case of Toyoura sand in FIG. 6, the reduction rate of the reduction rate of the gelation time in soil due to the increase in pH is shown in FIG. Chiba Prefecture
It is considerably gentler than the case of sea sand from the country.

That is, the gelation time reduction rate (%) in soil in the case of Toyoura sand is 60 (for low pH) to -50 (for high pH).
In the case of sea sand from Chiba Prefecture
Is across the range of about 90 to-100.

In the case of the present invention in the case of colloidal silica, as shown in FIGS. 7 and 9, the variation of the reduction rate (%) of the gelation time in soil due to the pH is gentler than that in the case of the above-mentioned activated silica. 60 ~ in Toyoura sand
0. The sea sand from Chiba Prefecture is in the range of 70 to -15.

In the comparative examples, the shortening rate (%) of the gelation time in soil was about 100 to 20 (FIGS. 6 and 8) in the case of active silicic acid, and 100 to 60 in the case of colloidal silica.
It is in the range of about (FIGS. 7 and 9) and is larger than the grout of the present invention in any pH range. In particular, the difference is remarkable in a high pH range of sea sand from Chiba Prefecture.

As described above, the grouting material for soil injection according to the present invention has a very small reduction in the gelation time in soil as compared with the conventional grouting material. Is rather prolonged.

[0080] In more detail observation, in the present invention, the citric acid-based symbol □, fractional shortening soil gel time in a condensed phosphate-based triangular indicia substantially the entire pH range is a relatively small tendency I understand.

6. Viscosity In Tables 1 to 5 for the activated silicic acid according to the present invention and Tables 6 and 7 for the comparison, the gelation time was from several minutes to several tens.
The change in viscosity at 20 ° C. was measured over time with respect to the blended liquid prepared so as to obtain the mixture in minutes. FIG. 10 shows the tendency of the change in viscosity with respect to the elapsed time (the ratio to the gelation time).

In FIG. 10, in the system according to the present invention,
It is concentrated almost in the range indicated by the oblique line of the curve (a). According to the present invention, the active silicic acid-sulfuric acid-sodium hydroxide system of the comparative example is concentrated near the curve (b), and the water glass-sodium hydrogen sulfate system of the comparative example is concentrated around the curve (c). It can be seen that the shaded portion of (a) is lower in viscosity than the comparative examples (b) and (c), and that the gelation occurs.

Tables 8 to 12 of the colloidal silica of the present invention
And Comparative Tables 13 and 14, the same tests as those for the above-mentioned activated silicic acid were conducted. Although the viscosity was slightly higher than that in the case of FIG. 10, the tendency was almost the same. This is probably because the concentration of colloidal silica and SiO ₂ was higher than that of the activated silicic acid used in this example.

7. Consolidation strength Sand gels made of Toyoura sand and sea sand from Chiba prefecture were prepared using the test compounded liquids of the above examples and comparative examples, and the uniaxial compressive strength of 7 days old was measured. Table 15 shows the results.

[0085]

[Table 15]

From Table 15, it can be seen that, in general, the grout material of the comparative example shows a considerable change in strength, but the grout material of the present invention has less change than the grout material of the comparative example, and shows that Although it takes a long time, there is almost no difference in strength.

Table 15 shows that colloidal silica has a relatively higher strength than active silica. This seems to be due to the fact that the colloidal silica used in the present example contains a thicker amount of SiO ₂ than the activated silicic acid.

In the above examples, as the sequestering agent,
Examples include ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, citric acid, sodium pyrophosphate, sodium hexametaphosphate, and sodium acid pyrophosphate. Examples of phosphate compounds other than condensed phosphates include phosphoric acid and dihydrogen phosphate. Sodium and sodium dihydrogen phosphate are taken as examples, but of course, other sequestering agents and phosphoric acid compounds other than those described in the text have the same effect, albeit to some degree.

As described above, the grouting material for ground injection according to the present invention can greatly reduce the gelation time in the ground, so that the soil gelation time can be kept long, and the grounding time is relatively low just before gelation. Since the viscosity is maintained, it is excellent in permeability and exhibits a consolidation strength suitable for conventional grout, and a very favorable effect can be expected particularly for prevention of liquefaction.

[0090]

The ground consolidating method according to the present invention has the following effects.

1. Since the shortening of the gel time in the ground can be reduced, the gel time in the soil can be kept long.

[0092] 2. Relatively low viscosity is maintained until just before gelation.

3. As described above, although the gelation is prolonged, it shows a consolidation strength substantially suitable for a conventional water glass grout.

4. Therefore, it has excellent permeability and is particularly effective in preventing liquefaction.

[Brief description of the drawings]

FIG. 1 is a particle size accumulation curve of Toyoura sand and sea sand from Chiba prefecture.

FIG. 2 is a graph showing the relationship between pH and soil gelation time for activated silicic acid and Toyoura sand.

FIG. 3 is a graph showing the relationship between pH and soil gelation time for colloidal silica and Toyoura sand.

FIG. 4 is a graph showing the relationship between the pH and the gelation time in soil for activated silicic acid and sea sand from Chiba Prefecture.

FIG. 5 is a graph showing the relationship between pH and soil gelation time for colloidal silica and sea sand from Chiba Prefecture.

FIG. 6 is a graph showing the relationship between the pH of activated silicic acid and Toyoura sand and the rate of reduction of the gelation time in soil.

FIG. 7 is a graph showing the relationship between the pH of colloidal silica and Toyoura sand and the gelation time reduction rate in soil.

FIG. 8 is a graph showing the relationship between the pH of activated silicic acid and sea sand from Chiba Prefecture and the rate of reduction of the gelation time in soil.

FIG. 9 is a graph showing the relationship between the pH of colloidal silica and sea sand from Chiba Prefecture and the rate of reduction of the gelation time in soil.

FIG. 10 is a graph showing a change in viscosity with respect to an elapsed time after blending of the grout material of the present invention using activated silicic acid and the grout material of Comparative Example.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-54-73407 (JP, A) JP-A-4-202594 (JP, A) JP-A-60-53588 (JP, A) JP-A-60-1985 144382 (JP, A) JP-A-4-298598 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09K 17/00-17/50

Claims (2)

(57) [Claims] And 1. A water glass active silicic or colloidal silica obtained by treating with a cation exchange resin, grout containing and any one or both as an active ingredient of sequestering agents and phosphate compounds Note in the ground
And sequestering the sequestering agent in the grout material in the ground.
Of insoluble metal salts by reacting with trace metals in
Sequester trace metals, or additionally, in the grout material
Insoluble by reacting phosphate compounds with trace metals in soil
Phosphates to block trace metals and block these
Action between silica in grout and trace metals in soil
Inhibits the reaction, whereby the grout material
Reduces gel time even when in contact with soil to increase permeability
To consolidate the ground over a wide area to prevent liquefaction of the ground.
A ground consolidation method characterized by being suitable for stopping. 2. A soil consolidation method according to claim 1 of the sequestering agent according to claim 1 is selected from the group of citric acid and condensed phosphates.