JP6134955B2 - Solidification material for ground injection - Google Patents

Description

  The present invention relates to a consolidation material for ground injection, and particularly relates to a consolidation material for ground injection that has good permeability to the ground during ground injection and has a low shrinkage rate during consolidation.

2. Description of the Related Art Conventionally, as a solid material for ground injection useful for ground liquefaction prevention injection work, for example, a ground injection solid material containing sodium silicate and an acid component is known. As sodium silicate (water glass), so-called No. 5 sodium silicate (molar ratio represented by SiO ₂ / Na ₂ O is about 3.7), No. 3 sodium silicate (SiO ₂ / Na ₂ O represented by mol) The ratio is about 3.2). In addition, in order to increase the SiO ₂ content of the ground-injection consolidated material, a combination of water glass and colloidal silica is also known.

  Specifically, Patent Document 1 discloses a grout obtained by adding sulfuric acid, phosphoric acid, aluminum chloride or the like as a reaction agent to a mixture of colloidal silica and water glass (alkaline silica solution). ) Is described. In particular, in the paragraph [0029], “For example, an acidic reagent can be added to an alkaline silica solution to adjust the solution to an acidic to neutral region to obtain a grout having a predetermined gelation time”. Have been described.

However, the conventional consolidation material for ground injection has the following problems. That is, the conventional consolidation material for ground injection sometimes mixes colloidal silica with water glass in order to increase the SiO ₂ content. Insufficient permeability. Moreover, in the case of a water glass-based ground-injection consolidated material that does not contain colloidal silica, there is a problem that the shrinkage rate during consolidation is large.

  Therefore, development of a consolidation material for ground injection that has improved these problems is desired.

JP 2001-3047 A

  An object of the present invention is to provide a ground-injection consolidated material having good permeability to the ground at the time of ground injection and having a small shrinkage rate at the time of consolidation.

  As a result of intensive studies to achieve the above-mentioned object, the present inventor is able to achieve the above object by a solid injection material obtained by mixing a specific high molar ratio sodium silicate, an acid component and water. As a result, the present invention has been completed.

That is, the present invention relates to the following consolidation material for ground injection.
1. By mixing high molar ratio sodium silicate having a SiO ₂ / Na ₂ O molar ratio of 3.8 to 5.3 and a SiO ₂ concentration of 17% by mass or more, an acid component, and water. A grounding consolidation material obtained,
(1) the high molar ratio sodium silicate after preparing the mixture molar ratio represented by _SiO 2 / Na ₂ O is a 3.8 to 5.3 by mixing sodium silicate and active silicic acid, It is obtained by concentrating the liquid mixture and adjusting the SiO ₂ concentration of the liquid mixture to 17% by mass or more,
(2) the active silicic acid is silicotungstic acid colloid solution,
A consolidation material for ground injection characterized by this.
2. The consolidation material for ground injection according to Item 1, wherein the molar ratio is more than 5.0 and not more than 5.3.
3. Item 3. The consolidation material for ground injection according to Item 1 or 2, wherein the SiO ₂ concentration is 17 to 23% by mass.
4 . The ground according to any one of Items 1 to 3 , wherein the sodium silicate has a molar ratio represented by SiO ₂ / Na ₂ O of 3 to 5 and a SiO ₂ concentration of 10 to 30% by mass. Solidified material for injection.
5 . The active silicic acid, SiO ₂ concentration is 3 to 6 wt%, ground injection caking material according to any one of claim 1-4.

  Hereinafter, the ground injection consolidation material of the present invention will be described in detail.

The ground injection consolidation material of the present invention has a high molar ratio sodium silicate having a SiO ₂ / Na ₂ O molar ratio of 3.8 to 5.3 and an SiO ₂ concentration of 17% by mass or more, It is obtained by mixing an acid component and water.

The ground injection consolidation material of the present invention having the above characteristics is compared with a conventional ground injection consolidation material obtained by mixing sodium silicate 5 or sodium silicate 3, acid component and water. There is a characteristic that the shrinkage rate during consolidation is small. In the relationship with the a mixture of colloidal silica conventional product increased the SiO ₂ concentration, the solid strength during sintering in the same molar ratio is characteristic that large. Further, by using a specific high molar ratio sodium silicate, it is not necessary to mix colloidal silica in order to increase the SiO ₂ content, and the permeability to the ground is good at the time of ground injection.
(High molar ratio sodium silicate)
The manufacturing method of the high molar ratio sodium silicate is not limited as long as the specific molar ratio and SiO ₂ concentration are satisfied. However, the high molar ratio sodium silicate is manufactured by the following manufacturing method in consideration of the long-term stability of the high molar ratio sodium silicate. Those are preferred. That is, after preparing a mixed solution in which the molar ratio represented by SiO ₂ / Na ₂ O is 3.8 to 5.3 by mixing sodium silicate and activated silicic acid, the mixed solution is concentrated and mixed. those manufactured by the manufacturing method of adjusting the SiO ₂ concentration in the liquid to more than 17% by mass. Hereinafter, the manufacturing method will be exemplarily described.

  It does not limit as sodium silicate used with the said manufacturing method, The dilute solution which added and diluted with the commercial item can be used.

The molar ratio of sodium silicate (SiO ₂ / Na ₂ O) is not limited, but is preferably about 3 to 5, and more preferably about 3.1 to 3.8 because general-purpose sodium silicate can be used.

  As a silica density | concentration contained in a sodium silicate, about 10-30 mass% is preferable, and about 20-30 mass% is more preferable.

  The active silicic acid used in the production method is not particularly limited, and for example, a colloidal silicate solution obtained by subjecting a water dilution of the sodium silicate to dealkali treatment by ion exchange or electrodialysis can be used. The active silicic acid is not limited to a completely dealkalized one but may be a part of the alkali remaining.

SiO ₂ concentration of the active silicic acid is not critical, but about 3-6% by mass.

  In the manufacturing method, a mixed solution having a molar ratio of 3.8 to 5.3 (preferably 4.8 to 5.3) is obtained by mixing the sodium silicate (including a water dilution solution) and the active silicic acid. Prepare. By adjusting the molar ratio to more than 5.0 to 5.3 or less (preferably 5.1 or more and 5.3 or less), it is possible to reduce the shrinkage rate of the consolidated material for ground injection of the final product. (Test Example 39 to be described later) Here, especially according to the aspect which adds active silicic acid to sodium silicate, it is preferable at the point which can adjust a molar ratio more reliably, without making a liquid mixture into a neutral area | region.

Next, the mixed solution is concentrated to adjust the SiO ₂ concentration of the mixed solution to 17% by mass or more. The degree of concentration can be appropriately set according to the use of the final product, but considering stability and handleability, 17 to 23% by mass is preferable, and 18 to 22% by mass is more preferable. When the concentration of SiO ₂ after concentration exceeds 23% by mass, the viscosity becomes high and the handleability may be reduced.

  Although the concentration method is not limited, For example, what is necessary is just to concentrate using a rotary evaporator under heating (preferably about 40-60 degreeC).

  The high molar ratio sodium silicate obtained by the above concentration is excellent in long-term stability, and is a high molar ratio sodium silicate excellent in long-term stability that does not substantially change even after 100 hours from the preparation. . In a particularly preferred embodiment, excellent long-term stability is obtained such that no substantial change is observed even after 100 days from the preparation.

In particular, when the molar ratio is 4.8 to 5.2 and the SiO ₂ concentration is 18 to 22% by mass, a change is observed after 100 days from the preparation, as is apparent from the results of the test examples. Absent.
(Consolidating material for ground injection)
The consolidation material for ground injection according to the present invention is obtained by mixing the high molar ratio sodium silicate, the acid component, and water.

  The acid component is not limited, but sulfuric acid and / or phosphoric acid is preferable. These acids can be used in combination of a plurality of types. As these acids, commercially available acid solutions having an acid concentration of 50 to 80% by mass can be used as they are.

The mixing ratio of the acid component and water can be appropriately set according to the desired SiO ₂ content, pH, and gel time of the consolidation material for ground injection. In the present invention, SiO ₂ content of ground injection caking material is preferably 2 to 15 wt%, and more preferably 3 to 12 wt%. Moreover, pH and gel time are related, and when the use of the consolidation agent for ground injection is for liquefaction prevention, it is preferable to set pH to about 2 to 4 and gel time of 10 hours or more. On the other hand, it is preferable to set the pH to about 4 to 8 when the solidification material for ground injection is a quick setting to slow setting type (gel time of about 10 seconds to about 1 hour). Therefore, the mixing ratio of water may be set in terms of adjusting the SiO ₂ content, and the mixing ratio of the acid component may be set in adjusting the pH and gel time.

  Although the mixing method of the said component is not limited, For example, by putting a part of water in the container for preparation, and dropping the high molar ratio sodium silicate diluted with the acid component and the remaining water while stirring the water It is preferable to mix each component. By adopting such a mixing method, it is possible to efficiently mix the components and to effectively suppress the occurrence of corrosion of the preparation container due to the supply of the acid component.

By using the high molar ratio sodium silicate as a raw material, the ground injection consolidation material of the present invention does not need to be mixed with colloidal silica in order to increase the SiO ₂ content. Usually, the average particle diameter of silica (SiO ₂ ) contained in the colloidal silica used for the ground-injection consolidated material is 5 to 30 nm, and this large average particle diameter is the cause of insufficient permeability to the ground. However, in the present invention, since it does not contain colloidal silica, the permeability to the ground is good when the ground is injected.

  The consolidation material for ground injection of the present invention is useful for ground liquefaction prevention injection work or ground reinforcement work. In particular, it is advantageous in that it does not contain colloidal silica, has good permeability to the ground, and has a smaller shrinkage rate at the time of consolidation as compared with the conventional consolidation material for ground injection.

The consolidation material for ground injection according to the present invention is compared with the conventional ground injection consolidation material obtained by mixing No. 5 sodium silicate or No. 3 sodium silicate, an acid component and water. The shrinkage rate is small. In the relationship with the a mixture of colloidal silica conventional product increased the SiO ₂ concentration, the solid strength during sintering in the same molar ratio is characteristic that large. Further, by using a specific high molar ratio sodium silicate, it is not necessary to mix colloidal silica in order to increase the SiO ₂ content, and the permeability to the ground is good at the time of ground injection.

It is a figure which shows the ²⁹ Si-NMR spectrum of the sample (what passed about 20 days) of the test examples 9, 19, 24, ²⁹ , and 34. FIG. It is a diagram showing the ²⁹ Si-NMR spectrum of the sample in Test Example 9,19,24 (elapsed thing about 270 days). It is the figure which summarized the result of Table 3, and is a figure which shows the stable area | region and unstable area | region of the high molar ratio sodium silicate at the time of preparation 100 day progress. It is a figure which shows the measurement result of the uniaxial compressive strength of the test example 38. It is a figure which shows the measurement result of the shrinkage rate of the test example 39. It is a figure which shows the relationship between the molar ratio and the shrinkage | contraction rate in the material age 140 days in Test Example 39. It is a figure which shows the relationship between the salt concentration and shrinkage | contraction rate in the age of 140 days in Test Example 39.

  The present invention will be specifically described below with reference to test examples, examples and comparative examples. However, the present invention is not limited to the examples.

Test Examples 1-35
(Preparation of high molar ratio sodium silicate)
No. 5 sodium silicate (SiO ₂ concentration: 24.00% by mass, Na ₂ O concentration: 6.62% by mass, molar ratio: 3.74) was diluted with water to a silica concentration of 5.0% by mass. Active silicic acid was prepared through ion exchange resin. SiO ₂ concentration of the active silicic acid was about 4.7 wt%.

The above active silicic acid was added to No. 5 sodium silicate (the above stock solution) while stirring to prepare 5 types of high molar ratio sodium silicate before concentration. Specifically, a molar ratio of 4.8 (SiO ₂ concentration of 12% by mass), a molar ratio of 5.0 (SiO ₂ concentration of 12% by mass), a molar ratio of 5.1 (SiO ₂ concentration of 12% by mass), and a molar ratio of 5 5 (SiO ₂ concentration: 11% by mass) and a molar ratio of 5.3 (SiO ₂ concentration: 11% by mass), 5 types of high molar ratio sodium silicate (before concentration) were prepared.

High molar ratio sodium silicate having a molar ratio of 4.8 (before concentration: SiO ₂ concentration of 12% by mass), SiO ₂ concentration of 13% by mass, 14% by mass, 15% by mass, 16% by mass, 17% by mass, It concentrated 1% at a time so that it might become 18 mass%, 19 mass%, 20 mass%, and 22 mass%. The sample before the concentration was set as Test Example 1, and the samples of Test Examples 2 to 10 were sequentially formed for each SiO ₂ concentration.

High molar ratio sodium silicate having a molar ratio of 5.0 (before concentration: SiO ₂ concentration of 12% by mass), SiO ₂ concentration of 13% by mass, 14% by mass, 15% by mass, 16% by mass, 17% by mass, It concentrated 1% at a time so that it might become 18 mass%, 19 mass%, 20 mass%, and 21 mass%. The sample before concentration was designated as Test Example 11, and the samples of Test Examples 12 to 20 were prepared in order for each SiO ₂ concentration.

High molar ratio sodium silicate having a molar ratio of 5.1 (before concentration: SiO ₂ concentration of 12% by mass) is concentrated so that the SiO ₂ concentration becomes 18% by mass, 19% by mass, 20% by mass, and 21% by mass. did. The sample before concentration was defined as Test Example 21, and the samples of Test Examples 22 to 25 were sequentially formed for each SiO ₂ concentration.

High molar ratio sodium silicate having a molar ratio of 5.2 (before concentration: SiO ₂ concentration 11 mass%) is concentrated so that the SiO ₂ concentration is 18 mass%, 19 mass%, 20 mass%, and 21 mass%. did. The sample before concentration was set as Test Example 26, and samples of Test Examples 27 to 30 were sequentially formed for each SiO ₂ concentration.

High molar ratio sodium silicate having a molar ratio of 5.3 (before concentration: SiO ₂ concentration 11 mass%) is concentrated so that the SiO ₂ concentration is 18 mass%, 19 mass%, 20 mass%, and 21 mass%. did. The sample before concentration was defined as Test Example 31, and samples of Test Examples 32-35 were sequentially formed for each SiO ₂ concentration.

  Concentration was performed at 45-55 ° C. using a rotary evaporator.

A sample having a molar ratio of 4.8 and a SiO ₂ concentration of 12% by mass is denoted as MR4.8-12%. The correspondence between the test example number and each sample is as follows.

(Component analysis)
The specific gravity in the vicinity of 20 ° C. of the high molar ratio sodium silicate (each sample) obtained in Test Examples 1 to 35 was basically measured only by floating, but when the viscosity was high and could not be measured, weighed in a graduated cylinder, Calculated from weight and volume. The viscosity around 20 ° C. was measured with a B-type viscometer.

In component analysis, the alkali concentration by neutralization titration of the sample before concentration and the ignition residue at 1000 ° C. are measured. From the ignition residue, the alkali (Na ₂ O) content and the impurity (metal oxide) content measured separately are calculated. The silica concentration was subtracted. For the sample after concentration, only the alkali concentration was measured, and the silica concentration was calculated on the assumption that the molar ratio did not change.

The component analysis results of each sample are shown in Table 2.
(change over time)
Each sample was sealed in a plastic container and stored at room temperature (about 20 to 35 ° C.), and changes with time until 100 days later were observed with the naked eye. The change level was divided into 6 grades of 0-5. Table 3 shows the criteria for determining each change level. Five days after the preparation, white turbidity having a low change level was confirmed in the samples of Test Examples 32 and 33, but no change was observed after 100 hours of preparation. FIG. 3 shows the stable region and unstable region of high molar ratio sodium silicate when 100 days have passed since preparation. As is clear from FIG. 3, when the molar ratio is 4.8 to 5.3 and the SiO ₂ concentration is 17 to 23% by mass, the storage stability over a long period of time is ensured while ensuring appropriate fluidity. It can be seen that it can be maintained.
( ²⁹ Si-NMR measurement)
A ²⁹ Si-NMR spectrum of a sample having a SiO ₂ concentration of 20% by mass (having passed about 20 days) was measured (JEOL LAMBDA 400 was used). The measured spectrum is shown in FIG. As is clear from FIG. 1, all the spectra show clear peaks of Q ^{0 to} Q ³ , contain a lot of low molecular weight silicic acid species, and belong to sodium silicate instead of colloidal silica. With respect to Q ^4, width slightly with increasing molar ratio becomes wide, peak top is shifted to higher magnetic field side. This is thought to be because the particle size of the silica particles in the colloidal region increases with increasing molar ratio. In addition, FIG. 2 shows a ²⁹ Si-NMR spectrum of a sample having a molar ratio of 4.8, 5.0 and 5.1 and a SiO ₂ concentration of 20 mass% (about 270 days have passed). Even after about 270 days, it shows clear peaks of Q ^{0 to} Q ³ , which contains a lot of low molecular weight silicic acid species, and belongs to sodium silicate instead of colloidal silica.

Test Example 36
The active silicic acid was added to No. 5 sodium silicate (the above stock solution) with stirring to prepare a high molar ratio sodium silicate (molar ratio 4.0, SiO ₂ concentration 19% by mass) before concentration. This was concentrated until the SiO ₂ concentration became 23% by mass.

The analysis values of the concentrate were Na ₂ O: 6.09 wt%, specific gravity: 1.276, and viscosity: 41.0 mPa · s. When the concentrated solution after 100 days from the preparation was observed, substantially no change was observed.

Test Example 37
The active silicic acid was added to No. 5 sodium silicate (the above stock solution) with stirring to prepare a high molar ratio sodium silicate (molar ratio 4.5, SiO ₂ concentration 15% by mass) before concentration. This was concentrated until the SiO ₂ concentration became 18% by mass.

The analysis values of the concentrate were Na ₂ O: 4.25 wt%, specific gravity: 1.209, and viscosity: 13.2 mPa · s. When the concentrated solution after 100 days from the preparation was observed, substantially no change was observed.

Examples 1-3 and Comparative Examples 1-3
First, various silicate materials shown in Table 4 below were prepared. High molar ratio sodium silicate having a molar ratio of 5.1, a molar ratio of 4.8, and a molar ratio of 5.3 was prepared in accordance with the manufacturing methods of Test Examples 1 to 35. Commercially available products were used for the other silicic acid materials.

  A consolidation material for ground injection was prepared by mixing the components shown in Table 5 below. In any case, after putting a part of water into the preparation container, the other components were added dropwise while stirring the water to prepare a solid material for ground injection. Comparative Example 3 was prepared by adding colloidal silica to No. 5 sodium silicate (molar ratio 3.74) in advance to prepare a silicic acid raw material having a molar ratio of 5.1. The types of raw materials are different.

  In each of the examples and comparative examples, by adjusting the blending amount of each component, three types of ground injection consolidation materials having silica concentrations of 3, 6, and 10% by mass and pH values of 4, 3, and 2.2 were obtained. Prepared. All of the consolidation materials for ground injection were adjusted so that the gel time was 20 hours.

Test Example 38 (uniaxial compressive strength measurement)
The sand (Toyoura sand) was solidified by using the ground injection consolidation material prepared in Example 1 and Comparative Example 3 (both the silica concentration of the ground injection consolidation material was 6% by mass and pH 3). A specimen (diameter 5 cm, height 10 cm) was prepared, and the uniaxial compressive strength of the specimen was measured. Three specimens were prepared for each example and comparative example, and the average value was obtained.

The preparation method and measurement method of the specimen were as follows.
(1) The volume of the cylinder is determined from the cylinder mold (inner diameter 5 cm, height 12 cm).
(2) Weigh Toyoura sand so that the relative density is 50% with respect to the volume. Relative density varies depending on the type of sand, with a relative density of 100% being packed as tightly as possible, 0% being packed as loosely as possible, and 50% being an intermediate state.
(3) Put the ground injection solidifying material into the above-mentioned cylindrical mold, and pour so that the measured Toyoura sand is uniform.
(4) Wait until the consolidated material for ground injection gels and reaches a predetermined age.
(5) After gelation, the cylinder is adjusted to a height of 10 cm and used as a specimen.
(6) The specimen is compressed with a compressive strength measuring device, and the uniaxial compressive strength when the specimen is broken is measured. The unit of uniaxial compressive strength is (pressure / unit area).

  The measurement result of uniaxial compressive strength is shown in FIG. In FIG. 4, (1) is the measurement result of Example 1, and (2) is the measurement result of Comparative Example 3. As is clear from FIG. 4, it can be seen that Example 1 is superior to Comparative Example 3 in uniaxial compressive strength at each age.

Test Example 39 (Shrinkage rate measurement)
The shrinkage rate of the ground injection consolidated material produced in Example 1, Comparative Example 1 and Comparative Example 2 (both the silica concentration of the ground injection consolidated material was 6 mass% and the pH was 3) was measured. Two samples were prepared for each example and comparative example, and the average value was determined.

The shrinkage rate was measured as follows.
(1) A 250 cm ³ volumetric flask is prepared, 150 cm ^{3 of a} solid material for ground injection is added, and it waits until it gels and hardens.
(2) After setting, add water to the line showing 250 cm ³ . At this point, 100 cm ³ of water has been added.
(2) Take out water at regular intervals (every two days at first, every 14 days after solidification for every 14 days), and repeat the addition of water up to the line indicating 250 cm ³ to measure the amount of water.
(3) If the gel contracts before the water is replaced, the amount of water added next increases. For example, if the amount of water added for the first time is 100 g and the amount added for the second time is 106 g, the gel contracted by 6 cm ³ during this period. At this time, since the first gel is 150 cm ³ , the shrinkage rate is 4%.

  The measurement results of the shrinkage rate are shown in FIG. As is apparent from FIG. 5, it can be seen that after about 30 days after the material age, the shrinkage ratio with time was suppressed lower in Example 1 than in Comparative Example 1 and Comparative Example 2.

Next, a graph was prepared with the shrinkage rate of the gel after 140 days as the vertical axis and the molar ratio of sodium silicate used at that time as the horizontal axis (FIG. 6). In addition, a graph was prepared with the horizontal axis representing the salt concentration (the total concentration of SiO ₂ , Na ₂ O and H ₂ SO ₄ ) and the vertical axis representing the shrinkage rate (FIG. 7).

  From these graphs, the shrinkage ratio at a molar ratio of 5.0 and a molar ratio of 5.3 was calculated. The shrinkage was calculated in two ways, based on the molar ratio and based on the salt concentration. When based on the molar ratio, the relationship between the actually measured three points in FIG. 6 is expressed by a linear function (straight line) by the least square method, and the molar ratio 5.0 and the molar ratio 5.3 are substituted into the equation. Determined by When the salt concentration is based on the salt concentration of 5.0 (9.19%) and the molar concentration of 5.3 (9.04%), three points in FIG. This relationship was expressed as a linear function (straight line) by the least square method, and the salt concentration with a molar ratio of 5.0 and the salt concentration with a molar ratio of 5.3 were substituted into the equation.

  The calculation results are shown in Table 6 below. As is clear from the results in Table 6, it can be seen that the shrinkage rate can be kept lower when the molar ratio is larger than when the molar ratio is 5.0.

Claims (5)

By mixing high molar ratio sodium silicate having a SiO ₂ / Na ₂ O molar ratio of 3.8 to 5.3 and a SiO ₂ concentration of 17% by mass or more, an acid component, and water. A grounding consolidation material obtained,
(1) the high molar ratio sodium silicate after preparing the mixture molar ratio represented by _SiO 2 / Na ₂ O is a 3.8 to 5.3 by mixing sodium silicate and active silicic acid, It is obtained by concentrating the liquid mixture and adjusting the SiO ₂ concentration of the liquid mixture to 17% by mass or more,
(2) the active silicic acid is silicotungstic acid colloid solution,
A consolidation material for ground injection characterized by this.   The consolidated material for ground injection according to claim 1, wherein the molar ratio is more than 5.0 and not more than 5.3. The SiO ₂ concentration is 17-23 wt%, ground injection caking material according to claim 1 or 2. The sodium silicate _is the mole ratio represented by SiO 2 / _Na 2 O is 3-5, and, SiO ₂ concentration of 10 to 30 mass%, according to any one of claims 1 to 3 Soil Solidified material for injection. The active silicic acid, SiO ₂ concentration is 3 to 6 wt%, ground injection caking material according to any one of claims 1-4.

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