JP2005320410A - Chemical for ground stabilization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical for ground stabilization which requires few days to gel, even when a colloidal silica is used as a main agent, gels to yield a durable gel whose strength is retained over a long period of time and does not produce any "non-uniform gel" which looks like a smashed tofu (soybean curd) or sherbet after preparation of the chemical for ground stabilization. <P>SOLUTION: The chemical for ground stabilization has a pH of 3.5-4.5 and is prepared by combining a main agent liquid and a hardener liquid. The main agent liquid contains the colloidal silica, wherein the molar ratio of SiO<SB>2</SB>/Na<SB>2</SB>O is 30-80 and the average particle size is 4-10 nm, in an amount corresponding to 20 kg SiO<SB>2</SB>per 400 L of the chemical. The hardener liquid contains an inorganic salt which serves as an gelling agent and an acidic substance, wherein the inorganic salt contains 0.4-3.5 kg metal component per 400 L of the chemical. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chemical solution for ground stabilization formed by combining a main agent solution containing colloidal silica and a curing agent solution containing an inorganic salt and an acidic substance as a gelling agent.

  Conventionally, in order to reinforce a soft ground or stop a leaking ground, various chemicals are injected into the ground and gelled in the ground, and a ground stabilization method is known.

  There are various types of chemicals used in the ground stabilization method. Among them, the main solution of water glass aqueous solution is less expensive than other chemicals and less likely to cause pollution. A so-called water glass-based chemical for ground stabilization, which is a combination of a gelling agent and a gelling agent, is widely used.

  This water glass-based ground stabilization chemical has the advantage of a short gelation time and high gelation strength, while water glass and gelling agent are usually gelled in an alkaline region of pH 9-10. Therefore, after the gelation in the ground, the alkali is leached, and there is a possibility that the groundwater and the soil are contaminated with alkalinity. In addition, there is a problem regarding durability such as silica leaching from the ground once reinforced with alkali, and the strength decreases and loosens over time.

  In order to solve the above-described problems of the water glass-based chemical solution for ground stabilization, the following has been proposed as a chemical solution for ground stabilization using an alkali silicate solution having an extremely small sodium content compared to water glass.

Patent Document 1 discloses an aqueous solution containing 5 to 25% by weight of an alkali silicate liquid containing colloidal silica having a particle diameter of 4 to 6 nm as SiO ₂ and 0.05 to 1.5% by weight of Na ₂ O and having a pH of 8 to 10.5. A chemical solution for ground stabilization, characterized in that gelation time is 300 minutes or less containing 0.2 to 10.0 parts by weight of water-soluble magnesium salt made of magnesium sulfamate, magnesium sulfate, or a mixture thereof in 100 parts by weight of sol Is disclosed. However, when the gel time is in the range of 1 to 300 minutes, the chemical solution is infiltrated and injected at a low pressure / low speed in a situation where the penetration distance of the chemical solution to the ground is greatly increased, such as countermeasures for liquefaction of the ground of existing structures. It was difficult to apply to the scene.

In Patent Document 2, an alkali silicate liquid containing colloidal silica having an average particle diameter of 5 to 20 nm is used as a main agent, NaCl and / or KCl is used as a curing agent, and the amount of the curing agent is [NaCl and / or KCl] / SiO ₂ weight. A ground injection agent having a ratio = 0.1 to 0.4 is disclosed.

  However, the ground injection chemical solutions described in Patent Document 1 and Patent Document 2 have a problem that the gel body contracts with time after gelation and a problem that the strength expression immediately after gelation is insufficient. It was. Furthermore, after the preparation of the chemical solution, the gel body produced has a problem that the tofu is crushed or gels in a sherbet-like non-uniform manner.

In order to solve the problems of Patent Document 1 and Patent Document 2, the present applicant uses colloidal silica having an average particle diameter of 5 to 10 nm and a SiO ₂ / Na ₂ O molar ratio of 30 to 80 as SiO ₂ in a chemical solution. 5 to 23% by mass and the gelling agent is composed of the following components (a) and (b). The component (a) is 0.65 to 6.6% by mass with respect to SiO _{2 in} the chemical solution, and the component (b) Proposed Patent Document 3 which is a chemical solution for stabilizing the ground containing 2.5 to 82% by mass.

(a) Component: At least one selected from the group consisting of alkali hydrogen sulfate and monobasic phosphates.

Component (b): at least one selected from the group consisting of magnesium sulfate, magnesium chloride, aluminum sulfate, aluminum chloride, calcium chloride, potassium alum, sodium alum, magnesium acetate and magnesium lactate.

In Patent Documents 4 and 5, acid or an acid and an alkali metal neutral salt are mixed in a colloidal solution of silicic acid, the pH of the injection solution is 4-7 or 4-8, and the gelation time is 20 hours. A ground injecting method characterized by injecting a prepared infusion solution into the ground is disclosed.
Japanese Patent Publication No. 8-3091 Japanese Examined Patent Publication No. 6-62953 Japanese Patent Laid-Open No. 2001-19957 JP 59-93786 However, Patent Document 3 is effective in that the uniformity of the chemical solution, the initial strength and the long-term strength are good and the shrinkage of the gel body is small, but the gel time is in the range of several tens of seconds to several hours. However, it may be difficult to apply to situations where the penetration of the chemical solution at a low pressure and low speed is low, such as when liquefaction of the ground of existing structures is being attempted, or when the chemical solution is to penetrate into the ground significantly. It was.

  Furthermore, since Patent Document 4 and Patent Document 5 use only colloidal silica, the gel time can be secured up to 20 hours. Although it can be partially applied to scenes where the penetration distance is to be obtained significantly and scenes where the chemical solution is infused and injected at low pressure and low speed, various infusion methods such as intermittent injection are further used to further increase the permeability. There has been a demand for a chemical solution for soil stabilization having a long gel time of several days, which can be applied to the soil.

  Geltime that meets various construction conditions such as a situation where the penetration of the chemical solution to the ground is greatly obtained, such as countermeasures for liquefaction of the ground of such existing structures, and a situation where the chemical solution is infused and injected at low pressure and low speed There is a demand for a chemical solution for ground injection that has a unit of several days. Furthermore, there are few chemicals for ground stabilization using only colloidal silica without using water glass or the like as the main agent or curing agent, and the gel time is in units of a few days and hardens within the range of 1 to 4 days. Is the current situation.

The first problem of the present invention is a ground stabilization chemical solution that uses only colloidal silica without using water glass or the like as a main agent or a curing agent, and contains an acidic substance and an inorganic salt that is a gelling agent. An object of the present invention is to provide a chemical solution for ground stabilization in which the gel time of a chemical solution is 6 hours or more and 7 days or less even when the SiO ₂ concentration in the chemical solution is high.

  In finding the ground stabilization chemical solution of the first problem of the present invention and the ground stabilization method using the same, the performance criteria of the chemical solution to be set are set as follows, and when these performance criteria are all satisfied, The first object of the present invention has been achieved.

The prepared chemical is at 20 ° C.
(1) The gel time after preparation of the drug solution is in the range of 6 hours to 7 days.

(2) After preparation of the chemical solution, a gel in a state where the tofu is crushed, a sherbet-like gel, or a so-called non-uniform gel should not be formed.

  The second problem of the present invention is not only to solve the conventional problems, but even when colloidal silica is used as the main agent, the gel time of the chemical solution for ground stabilization is several days, and the strength of the gel body after gelation is To provide a ground stabilization chemical solution that does not deteriorate for a long period of time, has durability, and does not produce a gel like a crushed tofu or a sherbet-like gel, a so-called non-uniform gel after preparation of a chemical solution for ground stabilization It is in.

  In finding the ground stabilization chemical solution of the second problem of the present invention, the performance standard of the chemical solution to be the problem is set as follows, and when both of these performance standards are satisfied, the second problem of the present invention is achieved. It was said that it was done.

The prepared chemical is at 20 ° C.
(1) The gel time after preparation of the drug solution is in the range of 1 day to 4 days.

(2) The uniaxial compressive strength value of the formed gel body (sand gel) after 7 days of gelation is 0.10 N / mm ² or more.

(3) After the preparation of the chemical solution, a gel in a state where the tofu is crushed, a sherbet-like gel, or a so-called non-uniform gel should not be generated.

As a result of intensive studies to solve the first problem, the present inventors surprisingly used an inorganic salt that is a gelling agent and an acidic substance on the curing agent liquid side, and a main agent liquid containing colloidal silica; If the pH of the ground stabilization chemical solution formed by combining a gelling agent and a curing agent solution containing an acidic substance and the SiO ₂ mass in 400 L of the chemical solution are within a certain range, the gel time is 6 hours or more and 7 days or less, preferably 12 It can be in the range of not less than 4 days, more preferably not less than 1 day and not more than 4 days, and the performance that a gel such as crushed tofu after the preparation of a chemical solution or a so-called non-uniform gel is not generated. At the same time, the first invention of the present invention was completed.

That is, the first invention of the present invention is “for ground stabilization comprising a main agent solution containing colloidal silica and a curing agent solution containing an inorganic salt as a gelling agent, and a combination of these main agent solution and the curing agent solution. In the chemical solution, the main agent solution contains colloidal silica in an amount of 20 kg or more and 70 kg or less as SiO ₂ in the ground stabilization chemical solution 400 L, the hardener solution contains an inorganic salt and an acidic substance as a gelling agent, and the main agent solution and the hardener solution The ground stabilization chemical solution is characterized in that the pH of the combined chemical solution for ground stabilization is in the range of 3.5 to 6 and the gel time is 6 hours to 7 days.

  In addition, as a result of intensive studies to solve the second problem, the present inventors surprisingly used an inorganic salt that is a gelling agent and an acidic substance on the curing agent liquid side, and has a particle diameter in a specific range. By using a base solution containing an amount of colloidal silica and a specific range of gelling agent and a hardener solution containing an acidic substance as a ground stabilization chemical, the pH of the chemical is within a certain range, so that the gel time Can be lengthened up to several days, and the gel body (sand gel) formed has good uniaxial compressive strength, and has a gel or sherbet-like shape in which tofu is crushed after preparation of the chemical solution for ground stabilization. The second invention of the present invention was completed by knowing that the performance of gel so-called non-uniform gel was not satisfied at the same time.

That is, the second invention of the present invention comprises “a main agent solution containing colloidal silica having a SiO ₂ / Na ₂ O molar ratio of 30 to 80 and a curing agent solution containing an inorganic salt as a gelling agent. In the ground stabilization chemical solution that is a combination of a liquid and a curing agent solution, the main agent solution contains colloidal silica in an amount of 20 kg to 60 kg as SiO ₂ per 400 L of the ground stabilization chemical solution, and the colloidal silica has an average particle diameter of 4 nm to 10 nm. The hardener liquid contains an inorganic salt and an acidic substance as a gelling agent, and the metal component in the inorganic salt is in the range of 0.4 kg to 3.5 kg per 400 L of the ground stabilization chemical liquid, and the main agent liquid and the hardener The ground stabilization chemical solution is characterized in that the pH of the ground stabilization chemical solution in combination with the solution is from 3.5 to 4.5. "

  According to the ground stabilization chemical solution of the first invention of the present invention, it is possible to obtain performance that cannot be obtained by a conventional combination of a silicate colloid solution and a gelling agent / acidic substance, that is, a gel time of 6 hours to 7 days. In addition, a uniform gel can be obtained, the strength of the gel body formed immediately after gelation is good, and the ground can be stabilized more safely and reliably.

  According to the chemical solution for ground stabilization of the second invention of the present invention, performance that cannot be obtained by the conventional combination of alkali silicate and gelling agent, that is, a uniform gel is obtained, and the gel body formed is gelated. The strength development immediately after is good, and it is possible to obtain a gel time of several days, which is difficult to obtain with conventional colloidal silica as the main agent, and it is possible to stabilize the ground more safely and reliably. .

The colloidal silica used in the ground stabilization chemical solution of the present invention is obtained by removing most of the alkali metal ions from the liquid alkali metal silicate aqueous solution. For example, the zeolite ion exchanger, the ammonium ion exchange It is obtained by passing water glass through an ion exchange resin such as a body, adding further water glass to the generated silica sol at a temperature of about 80 to 90 ° C., and passing through the ion exchange resin again to perform ion exchange. This shows an aqueous dispersion medium of colloidal silica that has undergone further stabilization and concentration steps and the like. Examples of commercially available products include “Snowtex” manufactured by Nissan Chemical Industries, Ltd. and “Cataloid” manufactured by Catalyst Chemical Industries, Ltd. The colloidal silica used in the chemical solution for ground stabilization of the present invention can be used in a SiO ₂ / Na ₂ O molar ratio of 30 or more and 80 or less, and among them, the molar ratio may be in the range of 40 or more and 60 or less. preferable.

The colloidal silica used in the ground stabilization chemical solution of the first aspect of the present invention is preferably 20 kg or more and 70 kg or less, and preferably 20 kg or more and 50 kg or less as the SiO ₂ mass contained in 400 L of the ground stabilization chemical solution. Is more preferable. When the content of colloidal silica in the main agent liquid is more than 70 kg as SiO ₂ per 400 L of the ground stabilization chemical liquid, it becomes difficult to control the gel time of the ground stabilization chemical liquid to 6 hours or more. Further, if less than 20kg as SiO _2, in some cases the gel time of the chemical solution exceeds 7 days, or gel body after gelation 7 days (sand gel) strength is lowered undesirably. As the colloidal silica used in the ground stabilization chemical solution of the first invention of the present invention, those having an average particle diameter in the range of 4 nm to 15 nm can be suitably used, and the average particle diameter is 4 nm to 10 nm. More preferably. This is because the colloidal silica has an average particle diameter in the range of 4 nm to 15 nm, the stability of the colloidal silica, a uniform gel is easily formed after the preparation of the chemical solution, the gel time is easy to control, and the axis of the formed gel body This is because the compressive strength is also excellent.

The colloidal silica used in the ground stabilization chemical solution of the second invention of the present invention preferably has an average particle size in the range of 4 nm to 10 nm, more preferably 4 nm to 6 nm. . Further, it is preferable that colloidal silica is 20 kg or more and 60 kg or less, more preferably 28 kg or more and 40 kg or less as the mass of SiO ₂ contained per 400 L of the ground stabilization chemical solution. Most preferably, colloidal silica having an average particle diameter of 4 nm or more and 6 nm or less, an SiO ₂ / Na ₂ O molar ratio of 40 or more and 60 or less, and SiO ₂ per 400 L of the ground stabilization chemical solution in a range of 28 kg or more and 40 kg or less. Is to satisfy all. When the particle size of colloidal silica is smaller than 4 nm, the main agent solution is gelled, that is, the stability of the main agent solution is poor. Easy to form a gel. In addition, when the particle size of colloidal silica is larger than 10 nm, it is difficult to control the gel time or the uniaxial compressive strength of the formed gel body is poor. When the contained mass of colloidal silica in the main agent liquid is more than 60 kg as SiO ₂ per 400 L of the ground stabilization chemical liquid, it is difficult to control the gel time of the chemical liquid within the range of 1 to 4 days. In addition, when SiO ₂ is less than 20 kg, it is difficult to control the gel time of the chemical solution within the range of 1 to 4 days, or the gel body (sand gel) strength after 7 days of gelation does not reach 0.10 N / mm ^2. Inferior in strength.

  The gelling agent used in the curing agent solution of the present invention is preferably the following inorganic salt. As the inorganic salt, magnesium sulfate, magnesium chloride, aluminum sulfate, and calcium chloride can be preferably used. Among these, magnesium sulfate is particularly preferable in view of ease of preparation of gel time and handling properties.

  Moreover, although there is no restriction | limiting in particular as an acidic substance used in the hardening | curing agent liquid of this invention, the following can be illustrated. Examples thereof include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, and acidic salts such as sodium hydrogen sulfate, potassium hydrogen sulfate, sodium dihydrogen phosphate and potassium dihydrogen phosphate. Among these, it is particularly preferable to use sodium hydrogensulfate in consideration of handleability and availability.

  As described in the above inorganic salts, neutral salts and polyvalent metal salts of sulfates and hydrochlorides are preferably used, and when other gelling agent components are used, for example, when alkaline salts are used, It is not preferable in that the pH adjustment becomes complicated, or, for example, the alkali metal salt has a low ability to gel, so that the amount used in the field increases, or the gel cannot be gelled at a predetermined gel time. Any inorganic salt or acidic substance as a gelling agent that can be used in the present invention may be a commercially available product, but a highly pure one is preferred.

  The inorganic salt, which is a gelling agent used in the ground stabilization chemical solution of the present invention, is preferably used so that the metal component mass in the inorganic salt is 0.4 kg or more and 3.5 kg or less per 400 L of the chemical solution. When the metal component mass in the inorganic salt is less than 0.4 kg, the gel time may be longer than 4 days, which is not preferable. On the other hand, if it exceeds 3.5 kg, the gel time may be less than 1 day, which is not preferable.

  The amount of the acidic substance used in the ground stabilization chemical solution of the first invention of the present invention is not limited, but the pH of the ground stabilization chemical solution formed by combining the main agent solution and the curing agent solution is preferably in the range of 3.5 to 6. It is preferable to add so that the pH of the ground stabilization chemical solution is 3.5 to 5. If the pH of the chemical solution for ground stabilization is lower than 3.5, which is the range defined by the present invention, the gel time becomes longer than 7 days and the strength of the gel body is poorly expressed, which is not preferable. If it is higher than 6, the gel time is shorter than 6 hours, which is not preferable.

  The amount of the acidic substance used in the ground stabilization chemical solution of the second invention of the present invention is not specified, but the pH of the ground stabilization chemical solution formed by combining the main agent solution and the curing agent solution is in the range of 3.5 to 4.5. It is preferable to add so that it becomes. If the pH of the chemical solution for ground stabilization is lower than 3.5, which is the range defined by the present invention, the gel time becomes longer than 4 days and the strength of the gel body is unfavorably deteriorated. On the other hand, if it is higher than 4.5, the gel time is shorter than 1 day, which is not preferable.

  In the ground stabilization chemical solution according to the first aspect of the present invention, an inorganic salt and an acidic substance are not added as a curing agent solution, but directly added to and mixed with a main agent solution containing colloidal silica (also referred to as colloidal silica solution) under high concentration conditions. If the pH of the chemical solution is in the range of 3.5 or more and 6 or less, the prepared solution will gel for about 6 hours, and in severe cases within 1 hour. Is not preferable because all of the prepared solution is wasted.

  In the ground stabilization chemical solution of the second invention of the present invention, an inorganic salt and an acidic substance are not added as a curing agent solution, but directly added and mixed under high concentration conditions with a main agent solution containing colloidal silica (also referred to as colloidal silica solution). Even if it is a chemical solution for ground stabilization in the pH range (3.5 or more and 4.5 or less) defined by the present invention, the gel time cannot be set to several days and gelation occurs in less than one day.

  The gel time of the ground stabilization chemical solution of the second invention of the present invention is in the range of 6 hours to 7 days, preferably 12 hours to 4 days, more preferably 1 day to 4 days. If the gel time of the chemical solution for ground stabilization is less than 6 hours, it depends on the conditions of the ground, but generally the gel time is promoted when injected, so that the penetration distance of the chemical solution for ground stabilization cannot be obtained sufficiently. It becomes inefficient and is not preferable. In order to obtain the permeation distance of the chemical solution for ground stabilization, 12 hours or more is necessary. Further, considering the case of intermittent injection, one day or more is preferable. Moreover, when the gel time of the chemical solution for ground stabilization exceeds 7 days, it is not preferable because the chemical solution for ground stabilization after injection is easily affected by groundwater or the like. In consideration of strength development after gelation, the gel time is preferably 4 days or less.

As a method for preparing the ground stabilization chemical solution of the first invention of the present invention, the colloidal silica solution of the present invention alone or a mixture of colloidal silica and water is used as a main agent solution (hereinafter also referred to as A solution), An aqueous solution of an inorganic salt and an acidic component is used as a curing agent liquid (hereinafter also referred to as a B liquid), and the A liquid and the B liquid are adjusted so that the pH of the chemical liquid obtained by mixing the A liquid and the B liquid is in the range of 3.5 to 6. The method of mixing simultaneously is mentioned. If the inorganic salt of the present invention is added to the liquid A side, it will immediately gel or a sherbet-like non-uniform gel will be formed. Further, to increase the mass of SiO _2, i.e. the addition of acidic substance in solution A obtained by high adjust the SiO ₂ concentration, the gel in a few tens of minutes to several hours in the region pH of about 4-8 A solution When the operation is interrupted on site such as trouble, the prepared liquid A is cured and wasted. May end up. Moreover, in order to ensure stability of A liquid, when an acidic component is further added, it is possible to ensure stability in the area | region whose pH of A liquid is about 2-3, but the gel time 6 which this invention prescribes | regulates. It is difficult to prepare it for more than 7 hours.

As a method for preparing the ground stabilization chemical solution of the second invention of the present invention, the colloidal silica solution of the present invention alone or a mixture of colloidal silica and water is used as a main agent solution (hereinafter also referred to as A solution), An aqueous solution of an inorganic salt and an acidic component is used as a curing agent liquid (hereinafter also referred to as B liquid), and the liquid A is mixed so that the pH of the ground stabilization chemical liquid obtained by mixing A liquid and B liquid is in the range of 3.5 to 4.5 The method of mixing B liquid simultaneously is mentioned. If the inorganic salt of the present invention is added to the liquid A side, it will immediately gel or a sherbet-like non-uniform gel will be formed. Further, to increase the mass of SiO _2, i.e. the addition of acidic substance in solution A obtained by high adjust the SiO ₂ concentration, the gel in a few tens of minutes to several hours in the region pH of about 4-8 A solution Therefore, the standing time after preparing the liquid A, that is, the stability of the liquid A cannot be ensured. Moreover, in order to ensure the stability of A liquid, when an acidic component is further added, it is possible to ensure stability in the area | region whose pH of A liquid is about 2-3, but the gel time 1 which this invention prescribes | regulates. Difficult to prepare for ~ 4 days.

  In injecting the thus prepared ground stabilization chemical solution into the ground, for example, various injection tubes such as a single tube type, a double tube type, a multiple tube type, etc. can be used. A method of mixing and leading to the injection tube, a mixing part provided with the A liquid and the B liquid at the base, for example, a method of mixing in the Y-shaped tube and guiding to the injection pipe, and the A liquid and the B liquid independently of the injection pipe It is possible to use an appropriate method such as introducing into the ground from the injection pipe and mixing and mixing in the ground while injecting into the ground.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these Examples.

Examples and Comparative Examples Colloidal silica: Colloidal silica prepared by the methods described in U.S. Pat. No. 3,711,419, U.S. Pat. No. 3,714,064 and JP-A-62-7622 was used.

In Table 1, the main agent solution (A solution) was prepared as follows, and the stability of the main agent solution was confirmed.

Liquid A: Collected colloidal silica having an average particle size of 5 nm and a SiO ₂ / Na ₂ O molar ratio of 50 obtained by preparation so as to contain 36 kg of SiO ₂ mass, and diluted to 200 L with water. . An acidic substance was added to the main agent solution so that the pH became a predetermined value, and the stability was confirmed.

  In Experiment 8, the acidic substance and the gelling agent magnesium sulfate were added to adjust the pH to a predetermined value, and the stability was confirmed.

The measurement results of the stability of the prepared liquid are shown in Table 1.

  As described in Experiments 1 to 7 in Table 1, when an acidic substance is added to the main agent solution side containing colloidal silica as the main agent and the pH of the main agent solution is shifted to the acidic side, the pH of the main agent solution is changed to 4 to 8.5. Then, the stability of the main agent liquid is extremely impaired, and gelation occurs.

  Further, as described in Experiment 8, when an acidic substance and a gelling agent were added to the colloidal silica main component liquid, the stability was impaired even at a pH (3.5 to 6) within the range specified in the present invention. This is undesirable because it causes gelation.

  Therefore, it can be seen that in order to use the main agent solution in a stable state, it is necessary to add no acidic substance or the like to the main agent solution side or to lower the pH of the main agent solution to about 3.

Examples and Comparative Examples of the First Invention In Table 2, the main agent liquid (A liquid) and the curing agent liquid (B liquid) were prepared as follows, and the following items were evaluated.

Liquid A: A colloidal silica having a SiO ₂ / Na ₂ O molar ratio of 50 obtained by preparation was diluted with a stock solution or water to obtain Liquid A.

  Solution B: In 400L of the ground stabilization chemical solution, the gelling agent is dissolved or added in water so that the amount of the metal component in the inorganic salt is 1 kg, and the acidic substance is at the pH shown in Table 2. did. For the inorganic salt and acidic substance at this time, commercially available reagent grade 1 products were used.

  The liquid A and liquid B prepared as described above were mixed at a temperature of 20 ° C. and gelled to obtain a sand gel.

Table 2 shows the particle size of the colloidal silica used in the chemical solution in each test, the SiO ₂ content in the chemical solution, the type of inorganic salt / acidic substance, the pH of the chemical solution, the measurement results, the evaluation, and the overall evaluation.

  In addition, in the column of the measurement result in the table, “-” indicates a case where the uniformity evaluation of the solution immediately after mixing the liquid A and the liquid B described below is “x”, and “a uniform gel body cannot be obtained. So, it was not evaluated ", or the uniformity evaluation of the solution immediately after mixing the liquid A and liquid B is ○, but“ the gel time is longer than 7 days, so the gelation time and the sand gel body demolding time are discriminated. It means that it was difficult to do so and was not evaluated.

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

-Uniformity of solution immediately after mixing of liquid A and liquid B: Liquid A and liquid B were mixed well at a liquid temperature of 20 ° C., and the state of the gel body produced was observed.

Evaluation ○: After mixing the A and B solutions, a uniform gel was produced.

Evaluation x: After mixing the liquid A and the liquid B, the generated gel body was non-uniform.

Gel time: At a temperature of 20 ° C., the chemical solution in which the liquid A and the liquid B were mixed was left in the container, and the number of days required until the fluidity of the chemical solution disappeared was defined as the gel time.

Evaluation ○ The gel time of the chemical solution was in the range of 6 hours to 7 days.

Evaluation × The gel time of the chemical solution was less than 6 hours or longer than 7 days.

・ Development of strength after gelation: At a temperature of 20 ° C, a mixture of liquid A and liquid B is injected into the closest packed Toyoura cinnabar, and the gel body (sand gel) diameter formed is 5 cm x high. A uniaxial compressive strength value of 10 cm was measured.

・ Durability: At a temperature of 20 ° C, a ground stabilization chemical solution in which A liquid and B liquid are mixed into close-packed Toyoura sand, and the gel body (sand gel) diameter is 5 cm x 10 cm in height. The uniaxial compressive strength value of the material age 7 days and the uniaxial compressive strength value of the material age 1 year were measured.

Comprehensive evaluation 0: The evaluation of the uniformity and the gel time of the solution immediately after mixing of the liquid A and the liquid B was 0.

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

Experiments 9 to 16 show the influence of the SiO ₂ mass in colloidal silica contained per 400 L of the ground stabilization chemical solution on the performance of the ground stabilization chemical solution.

In Experiment 9 where 15 mass of SiO ₂ contained in the ground stabilization chemical solution 400L is less than the specified range of the present invention (20 kg or more and 70 kg or less), the gel time is extremely longer than 7 days, while 70 more than the specified range. In Experiment 16, since the gel time was as short as less than one day, the performance standard of the chemical solution for ground stabilization was not satisfied, and the object of the present invention could not be achieved.

  Experiments 17 to 24 show the effect of the pH of the chemical solution after mixing the A solution and the B solution on the performance of the chemical solution for ground stabilization. In the experiment 36 with 3.0, where the pH of the chemical solution for ground stabilization is lower than the range specified by the present invention (3.5 or more and 6 or less), the gel time is extremely long as 7 days or more, while in the experiment 39 with 4.8 higher than the specified range, the gel time is Since it was as short as less than 1 day, it did not meet the performance criteria of the chemical solution for ground stabilization, and the object of the present invention could not be achieved.

  Experiment 28 shows the effect on the performance of the chemical without adding an acidic substance to the curing agent. In Experiment 33 in which an acidic substance was not added to the curing agent solution, the solution immediately after mixing the A solution and the B solution was non-uniform, and the object of the present invention could not be achieved.

  Experiment 29 shows the influence on the performance of the chemical solution for ground stabilization when a gelling agent other than the provisions of the present invention is used as a comparative example. When a gelling agent other than those specified in the present invention was used, foaming occurred immediately after mixing of the liquid A and the liquid B, the evaluation criteria of the present invention were not satisfied, and the object of the present invention could not be achieved.

  Experiment 30 shows, as a comparative example, the effect on the performance of a chemical solution for ground stabilization when an acidic substance is added to the main agent solution. In the method of adding an acidic substance other than that of the present invention, since the gel time is as short as less than 6 hours, the performance standard of the chemical solution is not satisfied and the object of the present invention cannot be achieved.

  On the other hand, when the requirements of the present invention are satisfied (Experiments 10-15, 18-23, 25-27), the chemical solution for ground stabilization obtained by mixing the A solution and the B solution is not uniform. Without producing a gel, the gel time was in the range of 6 hours to 7 days, all satisfying the performance criteria of the chemical solution for ground stabilization, and the object of the present invention could be achieved.

  Furthermore, in Table 3, the main agent liquid (A liquid) and the hardening | curing agent liquid (B liquid) were prepared as follows, and the following items were measured.

Liquid A: As described above, colloidal silica having a SiO ₂ / Na ₂ O molar ratio of 50 obtained by dilution was diluted with a stock solution or water to obtain Liquid A.

  Solution B: The inorganic salt was dissolved or added to water so that the amount of the metal component described in Table 3 was reached, and the acidic substance was adjusted to the pH described in Table 3. For the inorganic salt and acidic substance at this time, commercially available reagent grade 1 products were used.

  The liquid A and liquid B prepared as described above were mixed at a temperature of 20 ° C. and gelled to obtain a sand gel.

Table 3 shows the particle diameter of the colloidal silica used in the chemical solution in each test, the SiO ₂ content in the chemical solution for ground stabilization, the type of inorganic salt / acidic substance, the pH of the chemical solution for ground stabilization, and the measurement results.

Each test method was performed in the same manner as described above.

  Since Experiments 31 to 45 satisfy the requirements of the present invention, the chemical obtained by mixing the liquid A and the liquid B does not form a non-uniform gel, and the gel time is within the range of 6 hours to 7 days. It can be seen that those satisfying the performance standard of the chemical solution and satisfying the requirements of the particularly preferable range can sufficiently achieve the object of the present invention as a soil stabilization chemical solution.

Examples and Comparative Examples of Second Invention In Table 4, a main agent liquid (A liquid) and a curing agent liquid (B liquid) were prepared as follows, and the following items were evaluated.

Liquid A: A colloidal silica having a SiO ₂ / Na ₂ O molar ratio of 50 obtained by preparation was diluted with a stock solution or water to obtain Liquid A.

  Liquid B: A commercially available reagent grade 1 was used for the component (a) and the acidic substance of the gelling agent.

  The liquid A and liquid B prepared as described above were mixed at a temperature of 20 ° C. and gelled to obtain a sand gel.

Table 2 shows the particle size of colloidal silica used in the chemicals in each test, the content of SiO _{2 in} the chemicals, the inorganic salt, the type of acidic substance and the mass of the inorganic salt, the pH of the chemicals, the measurement results, the evaluation and the overall evaluation Indicated.

  In addition, in the column of the measurement result in the table, “-” indicates a case where the uniformity evaluation of the solution immediately after mixing the liquid A and the liquid B described below is “x”, and “a uniform gel body cannot be obtained. So, it was not evaluated ", or the uniformity evaluation of the solution immediately after mixing the liquid A and liquid B is ○, but“ the gel time and the demolding time of the sand gel body are distinguished because the gel time is as long as 7 days or longer It means that it was difficult to do so and was not evaluated.

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

-Uniformity of solution immediately after mixing of liquid A and liquid B: Liquid A and liquid B were mixed well at a liquid temperature of 20 ° C., and the state of the gel body produced was observed.

Evaluation ○: After mixing the A and B solutions, a uniform gel was produced.

Evaluation x: After mixing the liquid A and the liquid B, the generated gel body was non-uniform.

Gel time: At a temperature of 20 ° C., the chemical solution obtained by mixing the A solution and the B solution was allowed to stand in the container, and the number of days required until the fluidity of the chemical solution disappeared was defined as the gel time.

Evaluation ○ The gel time of the chemical solution was in the range of 1 day to 4 days.

Evaluation x ... The gel time of the chemical solution was less than 1 day or longer than 4 days.

・ Development of strength after gelation: At a temperature of 20 ° C, a mixture of liquid A and liquid B is injected into the closest packed Toyoura cinnabar, and the gel body (sand gel) diameter formed is 5 cm x high. A uniaxial compressive strength value of 10 cm was measured.

Evaluation ○ The value of uniaxial compressive strength was 0.10 N / mm ² or more.

Evaluation x: The value of uniaxial compressive strength was less than 0.10 N / mm ² .

・ Durability: At a temperature of 20 ° C, the ground stabilization chemical solution, which is a mixture of liquid A and liquid B, is injected into the closest packed Toyoura sand, and the gel body (sand gel) diameter is 5cm x 10cm in height. The uniaxial compressive strength value of the material age 7 days and the uniaxial compressive strength value of the material age 1 year were measured.

Comprehensive evaluation 0: Evaluation of uniformity of solution immediately after mixing of liquid A and liquid B, gel time, and expression of strength after gelation were all 0.

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

  Experiments 54 to 59 show the influence of the average particle size of colloidal silica on the performance of the chemical solution for ground stabilization. In Experiment 54, in which the average particle diameter of colloidal silica is 2 nm, which is smaller than the specified range of the present invention (4 nm to 10 nm), the uniformity of the solution immediately after mixing of liquid A and liquid B is poor, while In some Experiments 58 and 59, the expression of strength immediately after gelation is low, or the gel time is as long as 7 days or longer, and the object of the present invention cannot be achieved without satisfying the performance criteria of the above-mentioned ground stabilization chemicals. It was.

Experiments 60 to 65 show the effect of the SiO ₂ mass in colloidal silica contained per 400 L of chemical solution on the performance of the chemical solution for ground stabilization. In the experiment 60 of 15 kg in which the SiO ₂ mass contained in the ground stabilization chemical solution 400 L is less than the specified range (20 kg or more and 60 kg or less) of the present invention, the gel time is extremely long as 7 days or more, while In Experiment 65, since the gel time was as short as less than 1 day, the performance standard of the chemical solution was not satisfied, and the object of the present invention could not be achieved.

  Experiments 66 to 77 show the influence of the mass of the metal component in the gelling agent contained per 400 L of the ground stabilization chemical solution on the performance of the chemical solution. In Experiment 66 where the metal component mass in the gelling agent contained per 400 L of the ground stabilization chemical solution is 0.3 kg, which is less than the specified range of the present invention (0.4 kg or more and 3.5 kg or less), the gel time is 5 to 6 days, which is long. On the other hand, in Experiment 77 of 3.9 kg which is larger than the specified range, the gel time was as short as less than 1 day, so the performance standard of the chemical solution for ground stabilization was not satisfied, and the object of the present invention could not be achieved.

  Experiment 78 shows the effect of the addition of an acidic substance to the hardener solution on the performance of the chemical solution for ground stabilization. In Experiment 78 in which an acidic substance was not added to the curing agent solution, the solution immediately after mixing the solution A and the solution B was non-uniform, and the object of the present invention could not be achieved.

  Experiments 79 to 84 show the influence of the pH of the chemical solution for ground stabilization after mixing of liquid A and solution B on the performance of the chemical solution for ground stabilization. Experiment 81 with 3.0, where the pH of the chemical solution for ground stabilization is lower than the range specified by the present invention (3.5 or more and 4.5 or less) has an extremely long gel time of 7 days or more, while Experiment 84 with 4.8 higher than the specified range has a gel time of 4.8. Since it was as short as less than one day, it did not meet the performance criteria of the chemical solution for ground stabilization, and the object of the present invention could not be achieved.

  Experiment 85 shows the effect on the performance of the chemical solution for ground stabilization when a gelling agent other than the provisions of the present invention is used as a comparative example. When a gelling agent other than those specified in the present invention was used, foaming occurred immediately after mixing of the liquid A and the liquid B, the evaluation criteria of the present invention were not satisfied, and the object of the present invention could not be achieved.

Experiment 86 shows the effect on the performance of the chemical solution for ground stabilization when an acidic substance is added to the main agent solution as a comparative example. In the method of adding an acidic substance other than the provisions of the present invention, the gel time is as short as less than 1 day, so that the performance standard of the chemical solution for ground stabilization is not satisfied, and the object of the present invention cannot be achieved. On the other hand, when the requirements of the present invention are satisfied (Experiments 55 to 57, 61 to 64, 67 to 76, 79 to 80, 82 to 83), the liquid A and the liquid B are mixed. The ground stabilization chemical solution does not form a non-uniform gel, and the gel body (sand gel) formed after 7 days has a uniaxial compressive strength value of 0.10 N / mm ² or more. The performance criteria of the present invention were satisfied and the object of the present invention was achieved.

Claims (2)

In the ground stabilization chemical solution consisting of a main agent solution containing colloidal silica and a hardener solution containing an inorganic salt that is a gelling agent, the main agent solution uses colloidal silica for ground stabilization. during chemical 400L includes 20kg or 70kg or less as SiO _2, the curing agent solution comprises an inorganic salt and an acidic substance is a gelling agents, pH of the soil stabilizing chemical solution comprising a combination of a base resin liquid and the curing agent solution is 3.5 or more A chemical solution for ground stabilization, characterized by being within a range of 6 or less and having a gel time of 6 hours or more and 7 days or less. Stable ground consisting of a main agent solution containing colloidal silica with an SiO ₂ / Na ₂ O molar ratio of 30 to 80 and a curing agent solution containing an inorganic salt as a gelling agent, and combining these main agent solution and hardening agent solution. In the chemical solution, an inorganic salt in which the main agent solution contains colloidal silica in an amount of 20 kg to 60 kg as SiO ₂ per 400 L of the ground stabilization chemical solution, the colloidal silica has an average particle size of 4 nm to 10 nm, and the curing agent solution is a gelling agent. And an acidic substance, the metal component in the inorganic salt is within the range of 0.4 kg to 3.5 kg per 400 L of the ground stabilization chemical solution, and the pH of the ground stabilization chemical solution that is a combination of the main agent solution and the curing agent solution Is a chemical solution for ground stabilization, characterized in that it is 3.5 or more and 4.5 or less.