JP2002194353A - Chemical solution for stabilizing ground and method for stabilizing ground with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical solution that is used for stabilizing grounds, well develops a strength just after gelled, and gives the gel which hardly shrinks, does not lower the strength for a long time, and has excellent durability. SOLUTION: In the chemical solution which is used for stabilizing grounds and comprises a combination of an alkali silicate solution (solution A) and a gelling agent solution (solution B), a solution containing colloidal silica having an average particle diameter of 5 to 10 nm and a SiO2/Na2O molar ratio of 45 to 70 is used as the solution A, and an aqueous solution containing an alkali metal bicarbonate, or the alkali metal bicarbonate and an alkali metal carbonate or an alkali metal chloride as the gelling agent component is used as the solution B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground stabilizing chemical liquid comprising a combination of an alkali silicate liquid and a gelling agent, and a ground stabilization method using this chemical liquid.

[0002]

2. Description of the Related Art Conventionally, there have been known ground stabilizing chemicals and ground stabilization methods in which various chemicals are injected into the ground to form a gel in the ground in order to strengthen a soft ground or stop water from leaking the ground. ing.

There are various chemicals used in the ground stabilization method. Among them, water glass aqueous solution and gelling agent are used because of their low cost and low risk of pollution compared to other chemicals. combining the door, so-called water glass-based soil stabilizing chemical is widely used. This medicinal solution has the advantages of a short gelation time and high gel strength.

[0004] However, since this water glass-based soil stabilizing solution is usually gelled in the alkaline region of pH 9 to 10, after gelling in the ground, the alkali is leached out and the groundwater and soil are contaminated with alkalinity. There is a risk of doing so. Further, there is also a problem in terms of durability such that silica is leached from the ground once strengthened by the alkali, and the strength is reduced with the lapse of time and the ground is loosened.

In order to solve such a problem of the water glass-based ground stabilizing solution, a ground stabilizing solution using an alkali silicate solution having an extremely small content ratio of a sodium component to a silica component as compared with a water glass solution. Has been proposed.

For example, Japanese Unexamined Patent Publication (Kokai) No. 62-79286 discloses a ground injection agent containing colloidal silica having an average particle size of 5 to 20 μm as a main component and a neutral salt of an alkali metal as a curing agent, wherein The neutral salt is NaCl and / or KCl, and the amount thereof is alkali metal neutral salt / SiO
₂ weight ratio is = 0.1 to 0.4 ground injection agent.

Further, in JP-A-59-179579, silica sol as a curing agent or auxiliaries and optionally injecting a modifier ground, the grouting method of solidifying, the silica sol is Na ₂ O 0. 6-5% by weight, SiO ₂ 3
-25% by weight, the curing agent is an organic solvent, the auxiliary is an inorganic solvent, and the adjusting agent is bicarbonate, and the curing agent and the auxiliary are used for the silica sol. Are used singly or in combination, respectively. And as the curing agent, butyrolactone, ethylene glycol diacetate, triacetin, ethylene carbonate or glyoxal, and as the auxiliary, phosphoric acid,
Use sodium sulfate, sodium carbonate, calcium chloride, potassium carbonate, sodium dihydrogen phosphate, sodium tripolyphosphate, magnesium sulfate, aluminum sulfate, sodium hydrogen carbonate, or calcium carbonate, and further use sodium hydrogen carbonate, potassium hydrogen carbonate as a modifier. And the use of lithium hydrogen carbonate.

[0008]

However, in any of the ground injections described in the above publications, the gel body largely shrinks with time after gelation, or the strength immediately after gelation is insufficient. There was a problem. Further, the gel strength may decrease with time, and there is also a problem in durability. In addition, there is a problem that uneven gelation such as crushed tofu or sherbet occurs.

Accordingly, an object of the present invention is to improve the above-mentioned problems of the conventional chemical solution for ground stabilization, exhibit good strength immediately after gelation, hardly shrink the gel, and hardly reduce the gel strength for a long time. It is an object of the present invention to provide a ground stabilizing chemical having excellent durability and a ground stabilization method using the same.

[0010]

SUMMARY OF THE INVENTION The present invention is an alkali silicate solution a (A solution) gelling agent solution (B solution) comprising a combination of a soil stabilizing chemical, the alkali silicate solution (A solution)
Contains colloidal silica having an average particle diameter of 5 to 10 nm, and has a SiO ₂ / Na ₂ O molar ratio of 45 to 70,
The gelling agent solution (B solution), as a gelling agent component, characterized by containing bicarbonate alkali alone or alkali metal bicarbonate salt and a chloride of alkali carbonate or alkali metal in solution It relates to a ground stabilizing chemical.

[0011] The present invention is a soil stabilizing chemical solution injected into the ground, when it is gelled to the soil stabilized with the ground, characterized by using the above ground stabilizing chemical as ground stabilizing chemical It relates to the ground stabilization method.

According to the present invention, a solution prepared by mixing a solution A and a solution B so as to have a SiO ₂ content of 47.58 kg and a gelling agent component content of 13.0 kg in 400 L of a solution prepared by mixing 20 solutions was prepared. As a result of evaluation at 0 ° C., the volume shrinkage of the gel after 3 years with respect to the volume of the gel immediately after gelation was less than 1%, and the uniaxial compressive strength of the gel (homogel) after 1 hour of gelation was 0%. 0.01 N / mm ² or more, and the uniaxial compressive strength of the gel after 3 years of gelation is:
It is possible to satisfy not only the uniaxial compressive strength of the gel after one hour of gelation but also the so-called non-uniform gel such as a gel in a state where crushed tofu or a sherbet-like gel is not generated. Become.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The alkali silicate solution (Solution A) constituting the ground stabilizing solution of the present invention has an average particle diameter of colloidal silica of 5 to 10 nm and a molar ratio of SiO ₂ / Na ₂ O of 45 to 45. 70. Further, the amount of SiO ₂ per 400 L of the chemical solution after mixing the solution A and the solution B is from 8.3 kg to 1
It is preferable to prepare an alkali silicate solution (Solution A) so as to be 10 kg. The gel strength tends to increase as the amount of SiO ₂ increases, and to decrease as the amount of SiO ₂ decreases. When the amount of SiO ₂ is too small strength becomes difficult to provide a sufficient effect after liquid injection into the ground, increasing the amount of gel strength decreases as the amount of SiO ₂ is too large with respect to the unit increment of SiO _2, Economic efficiency will also decrease.

The average particle diameter of the colloidal silica of the liquid A is 5
If it is smaller than nm, a so-called non-uniform gel is likely to be formed after mixing the solution A and the solution B. When the average particle size of the colloidal silica is larger than 10 nm, the strength immediately after gelation is poor, and the volume of the gel shrinks with time.

[0015] SiO ₂ / Na ₂ O molar ratio of the liquid A is less than 45, or become a low liable durability decreases over time gel strength, or temporal contraction of the gel is increased, not Or a uniform gel is formed. In addition, SiO ₂ /
When the molar ratio of Na ₂ O is higher than 70, the strength immediately after gelation is poor.

Solution A is described in US Pat. No. 3,711,419, US Pat. No. 3,714,064, and
Etc. -7622 JP can be prepared by known methods described, can also be used commercially available products.

The gelling agent solution (Solution B) constituting the ground stabilizing solution of the present invention is preferably an aqueous solution obtained by dissolving the gelling agent in water. Or a combination of an alkali hydrogen carbonate and an alkali carbonate or an alkali metal chloride.

The gelling agent solution (solution B) has a gelling agent amount of 5 k per 400 L of the drug solution after mixing the solution A and the solution B.
It is preferable to prepare so as to be g to 50 kg. At this time, the amount of the gelling agent per 200 L of the liquid B is 5 kg to 50 kg.
It is preferable to prepare the solution B so that the weight becomes kg. The curing time can be controlled by the amount of the gelling agent, and when the amount of the gelling agent is increased, the curing time can be shortened, and when the amount is decreased, the curing time can be extended.

Examples of the alkali hydrogencarbonate include sodium hydrogencarbonate, potassium hydrogencarbonate and lithium hydrogencarbonate, and sodium hydrogencarbonate and potassium hydrogencarbonate are preferred from the viewpoint of developing strength immediately after gelation. These can be generally used commercially available ones.

The alkali carbonate includes, for example, sodium carbonate, potassium carbonate and lithium carbonate, and sodium carbonate and potassium carbonate are preferred from the viewpoint of developing strength immediately after gelation. These can be generally used commercially available ones.

As the alkali metal chloride, for example,
Examples thereof include sodium chloride, potassium chloride, and lithium chloride, and sodium carbonate and potassium carbonate are preferable from the viewpoint of developing strength immediately after gelation. These can be generally used commercially available ones.

The present invention combines the alkali silicate solution (solution A) defined in the present invention and the gelling agent solution (solution B) defined in the present invention to form a so-called liquid after mixing the solution A and the solution B. It is possible to provide an excellent ground stabilizing chemical solution in which a non-uniform gel is not generated, the strength of the gel immediately after gelation is excellent, the strength of the formed gel and the stability over time of the volume are high. .

The soil stabilization method of the present invention, the present alkali silicate solution as defined in the invention (A solution) gelling agent solution as defined in the present invention (B solution) comprising a combination of a soil stabilizing chemical liquid in soil And the mixture of solution A and solution B is gelled,
The ground is stabilized by the formed gel.

When the ground stabilizing solution is injected into the ground, an alkali silicate solution (solution A) and a gelling agent solution (solution B) are mixed in advance, and the resulting mixed solution is led to an injection pipe leading to the ground. A method of injecting into the ground, an alkali silicate solution (solution A) and a gelling agent solution (solution B) are separately sent and mixed in a mixing section provided at the base of the chemical solution injection device, for example, a Y-shaped pipe; A method in which the formed mixed solution is guided into an injection pipe leading into the ground and injected into the ground, an alkali silicate solution (A solution) and a gelling agent solution (B
Liquid) are independently guided into an injection pipe leading into the ground, injected into the ground, and merged and mixed in the ground.

The liquid injector generally has a tank for storing the liquid A and the liquid B, respectively, and an injector having a pump for feeding the liquid. The injection device is connected to an injection pipe for injecting a chemical into the ground, and the chemical is injected into the ground from the tip of the injection pipe. An inlet pipe such as a pressure-resistant hose is used for a connection line from the tank for liquid A and the tank for liquid B to the injection pipe, and a chemical solution in each tank is sent to the injection pipe by a pump such as a cloud pump. The mixing part of the liquid A and the liquid B is, for example, Y
A tube is used and is placed just before the drug solution enters the injection tube, that is, at the top of the injection tube. Mixing of liquids A and B may be provided in the middle of the injection pipe may be provided at the tip of the injection tube. Also, without providing such a mixing section,
The liquid A and the liquid B may be mixed in advance in the mixing tank and then fed. Furthermore, without providing such a mixing tank or a mixing section, it is also possible to adopt a configuration in which one chemical solution is injected into the ground, and then the other chemical solution is injected, and the two chemical solutions are mixed in the ground. Various injection tubes such as a single tube type, a double tube type, and a multiple tube type can be used as the injection tube.

[0026]

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

The alkali silicate solution (Solution A) was prepared as shown in Table 1
Using the following having an iO ₂ / Na ₂ O molar ratio and an average particle size of colloidal silica, 200 L of alkali silicate solution
It was prepared such that the content of SiO ₂ therein became 47.58 kg.

The average particle size of the colloidal silica was measured by Sears titration (NaOH titration). This method
The average specific surface area is determined from the amount of Na adsorbed on silica, and from this value, the average particle diameter when the silica particles are regarded as spheres is calculated.

The alkali silicate solutions of Experiments Nos. 4, 12, and 15 to 35 were manufactured by Catalyst Chemicals Co., Ltd.
I-350 "was diluted with tap water and used.

The alkali silicate solution of Experiment No. 7 was prepared by diluting "Cataloid SI-500" manufactured by Catalyst Chemical Industry Co., Ltd. with tap water.

As the alkali silicate solution of Experiment No. 9, "Cataloid SI-550" manufactured by Catalyst Chemical Industry Co., Ltd. was diluted with tap water and used.

The alkali silicate solutions of Experiment No. other than the above are described in US Pat. No. 3,711,419 and US Pat.
Those prepared according to the methods described in JP-A-714064 and JP-A-62-7622 were used.

The gelling agent solution (Solution B) has a gelling agent of 13 k
g was weighed, and water was added and dissolved in an amount such that the amount of solution B became 200 L.

As the gelling agent consisting of two components, a gelling agent component was put into a Nauta mixer and mixed for 30 minutes so that the weight of the solid content after mixing was 1 t (ton). The gelling agents used were all reagent grade ones.

Table 1 shows that SiO ₂ /
Na ₂ O molar ratio, the average particle size of colloidal silica, the kind and blending ratio of the gelling agent component of the B liquid is shown. Here, the mixing ratio of the gelling agent components (1) and (2) indicates the content (% by mass) with respect to the entire gelling agent component.

The solution A and the solution B prepared as described above were mixed at a temperature of 20 ° C. and gelled to obtain a homogel. Table 2 shows the measurement results and the evaluation results.

The test methods and evaluation criteria for each evaluation item of the chemical solution performance are as follows.

<Uniformity of Liquid A and Liquid B Immediately After Mixing> Liquid Temperature 2
At 0 ° C., Solution A and Solution B were mixed well, and the state of the mixture immediately after mixing (up to about 30 seconds after mixing) was visually observed.

[0039] Evaluation ○: uniform liquid state (sol state) silica particles are dispersed.

Evaluation X: An uneven state in which a gel like crushed tofu or a sherbet-like gel was formed.

<Development of strength immediately after gelation> Temperature 20 ° C
In the above, a mixed solution of the liquid A and the liquid B is applied to a cylindrical mold (with an inner diameter of 5 mm).
cm × poured to a height 10 cm) in, was measured uniaxial compressive strength of the gel of 1 hour after the time when the gel formed.

Evaluation 〇: The value of the uniaxial compressive strength is 0.01 N /
mm ² or more.

Evaluation X: The value of the uniaxial compressive strength is 0.01 N /
less than mm ^2.

<Durability of Gel> At a temperature of 20 ° C., A
A liquid mixture of the liquid B and the liquid B is poured into a cylindrical mold (inner diameter 5 cm × height 1).
0 cm), and the uniaxial compressive strength of the gel 1 hour after the gel was formed and the uniaxial compressive strength 3 years later were measured.

Evaluation 〇: Uniaxial compressive strength of gel after 3 years was 1
More than the uniaxial compressive strength of time after the gel.

Evaluation X: The uniaxial compressive strength of the gel after 3 years was 1
Less than uniaxial compressive strength of gel after time.

<Shrinkability of Gel> At a temperature of 20 ° C., A
A liquid mixture of the liquid B and the liquid B is poured into a cylindrical mold (inner diameter 5 cm × height 1).
0 cm), and the gel volume immediately after gelation (at the time when the gel is formed), and the gel that has been deformed 1 hour after gelation are cured in water, and the volume of the gel 3 years later is measured. The shrinkage rate of the volume was determined by

Volume shrinkage (%) = 100 × [gel volume (immediately after gelation) −gel volume (after 3 years)] / gel volume (immediately after gelation) 〇: Volume shrinkage is less than 1.0%.

C: Volume shrinkage of 1.0% or more.

<Comprehensive Evaluation> 〇: The uniformity immediately after mixing of the liquid A and the liquid B, the strength development immediately after gelation, the durability of the gel, and the evaluation of the gel shrinkage were all 〇.

X: At least one of the evaluation items was x.

The curing time in the table is the result of measuring the time from mixing the solution A and the solution B at 20 ° C. to almost completely solidifying by gelation.

[0053]

[Table 1]

[0054]

[Table 2]

Experiment Nos. 1 to 6 show the influence of the average particle size of colloidal silica in the alkali silicate solution on the performance of the chemical solution. In Experiment No. 1 in which the average particle size of the colloidal silica in the alkali silicate solution (Solution A) was 3 nm, which was smaller than the specified range of the present invention, the uniformity immediately after mixing of Solution A and Solution B was low. In Experiment No. 6 in which the particle size was 13 nm, which was larger than the specified range, the performance was low in terms of the strength development immediately after gelation and the gel shrinkage, and the object of the present invention could not be achieved.

Experiments Nos. 8 to 14 show the influence of the SiO ₂ / Na ₂ O molar ratio of the alkali silicate solution (Solution A) on the chemical performance. Experiment No. 8 (SiO ₂ / N) in which the SiO ₂ / Na ₂ O molar ratio of the alkali silicate solution was smaller than the specified range of the present invention
When the a ₂ O molar ratio is 6), the uniformity immediately after mixing of the liquid A and the liquid B is poor. In Experiments Nos. 9 and 10 (SiO ₂ / Na ₂ O molar ratios are 15 and 40, respectively), the gel durability is poor. Low and high shrinkage. On the other hand, in Experiment No. 14, in which the molar ratio was 80, which was larger than the specified range of the present invention, the strength immediately after gelation was low, and in any case, the object of the present invention could not be achieved.

In Experiment No. 7, both the SiO ₂ / Na ₂ O molar ratio and the average particle size of the colloidal silica were lower than the specified range of the present invention, and the object of the present invention could be achieved in all the evaluation items. Did not.

In Experiments Nos. 15 to 35, the gelling agent solution (B
2 shows the effect of the gelling agent component of the liquid on the chemical liquid performance. The object of the present invention can be achieved by using a B solution containing a gelling agent component defined by the present invention, and a B solution containing another component is used.
With the liquid, the object of the present invention could not be achieved.

[0059]

According to the soil stabilizing solution and the ground stabilization method of the present invention, the performance which cannot be obtained by the combination of the conventional alkali silicate and the hardening agent, that is, the gel strength immediately after gelation is excellent. In addition, the performance that the formed gel is uniform, excellent in durability of strength and small in shrinkage ratio is obtained, and as a result, the ground can be more safely and reliably stabilized.

Claims (2)

[Claims] 1. A ground stabilizing solution obtained by combining an alkali silicate solution (Solution A) and a gelling agent solution (Solution B), wherein the alkali silicate solution (Solution A) has an average particle diameter of 5 to 10 n.
m of colloidal silica and SiO ₂ / Na ₂ O
The molar ratio is 45 to 70, and the gelling agent solution (Solution B) dissolves an alkali hydrogen carbonate alone or an alkali hydrogen carbonate and an alkali carbonate or an alkali metal chloride as a gelling agent component. A ground stabilizing solution characterized by being contained in a state. 2. The ground stabilizing chemical according to claim 1, wherein the ground stabilizing chemical is injected into the ground and gelled in the ground to stabilize the ground. Ground stabilization method.