JP5305586B2 - Ground injection agent and ground injection method using the same - Google Patents

Description

  The present invention relates to a ground injecting agent used in ground improvement work and water stop work in various civil engineering works and a ground pouring method using the same.

  In order to stabilize natural ground and ground in tunnel civil engineering and urban civil engineering, chemical-type ground injection agents have been used. As this ground injection agent, a suspension type containing cementitious particles and a solution type not containing cementitious particles are known.

  The suspension type has the merit that the strength development is excellent, but the penetrability of the chemical solution is low, so that it is not suitable for a dense sandy layer having a small particle interval. Among the suspension types, cement-based injectants were not suitable for waterstop work because of their long gel times.

On the other hand, the solution type is suitable for a dense sandy layer having a small particle interval and water-stopping work because it has high chemical permeability.
The solution-type injection is an injection that uses a compound that dissolves in water, and uses an organic solution, an acid, and an alkaline solution alone or in combination (see Patent Documents 1 to 6).
JP 52-11505 A Japanese Examined Patent Publication No. 57-047226 JP 52-087807 A Japanese Patent Laid-Open No. 51-082913 JP-A-52-120507 JP-A-57-195786

  As inorganic salts used in the above-described solution-type injections, for example, carbonates, chlorides, sulfates, borates, and phosphates are known. Examples of the organic solution include esters-acetic acid monoether glycol, propylene carbonate, aldehydes-formaldehyde, methyl formate, and glyoxal. Examples of the acid include sulfuric acid.

In addition, there is a demand for a product that gels immediately after injection and stabilizes the ground. However, “(1) sodium silicate, (2) glyoxal, (3) water-soluble aluminum salt, and ( 4) Invention of ground injecting agent using a water-soluble organic acid, an aqueous mixed solution to which at least one of a water-soluble inorganic acid and a water-soluble acidic inorganic salt is added ”(Patent Document 7) As described above, it took several minutes from the mixing of the main agent and the reactant to gelation.
JP-A 62-199684

Further, Patent Documents 8 to 10 disclose an invention of a ground injection capable of adjusting gel time containing water glass and an acidic material as active ingredients, and an organic acid such as acetic acid, citric acid or gluconic acid is used as the acid. (Patent Document 8, Paragraph [0043], Paragraph [0094] Table 2, Paragraph [0048], Paragraph [0048], Paragraph [0103], Patent Document 10, Paragraph [0052], Paragraph [ [0117] Table 2) does not show the use of organic acid salts (carboxylates) to adjust the gel time.
JP 2004-196915 A JP 2004-196922 A JP-A-2005-75899

Further, Patent Document 11 discloses a “ground injection agent comprising an aqueous solution A containing an alkali metal silicate and an aqueous solution B containing an alkali metal aluminate and an organic acid” (Claim 1). In this invention, it is shown that sodium citrate is used, and this sodium citrate is shown as being equivalent to organic acids such as citric acid, gluconic acid, malic acid, tartaric acid (paragraph [0014]. ], [0021], [0027], [0028]), and is not particularly used for adjusting the gel time, and also requires a specific reagent called “alkali metal aluminate”. Therefore, it is suggested to use sodium citrate to adjust the gel time when using inorganic salts other than alkali metal silicate and "alkali metal aluminate". Not.
JP 2005-146161 A

Patent Document 12 also discloses a “ground injection agent composed of an aqueous solution A containing an alkali metal silicate and an aqueous solution B containing an alkali metal aluminate, an alkali metal carbonate, and an organic acid.” In the invention of claim 1), it is shown that sodium citrate is used, but this sodium citrate is shown to be equivalent to organic acids such as citric acid, gluconic acid, malic acid, tartaric acid and the like. (Paragraphs [0015], [0022], [0028], [0029]), not specifically used to adjust the gel time, and also specified as “alkali metal aluminate, alkali metal carbonate” In this case, the gel tie when using an alkali metal silicate and an inorganic salt other than “alkali metal aluminate, alkali metal carbonate” is essential. To adjust, not intended to suggest that the use of sodium citrate.
JP 2005-146163 A

  Further, in these techniques, it is necessary to change the kind of the reactant or the mixing ratio of the main agent and the reactant in order to prepare the gel time. At the construction site, the main agent and the reactant are often separately pumped and used with a double injection pump. However, due to the structure of the dual pump, the main agent and the reactant are pumped in equal volumes. For example, there is one kind of reactant, and it is highly convenient that the gel time can be adjusted by changing its concentration.

  It is an object of the present invention to provide a ground injecting agent in which gel time can be easily adjusted and the outflow of a solution after curing is small, and a ground injecting method using the same.

  As a result of repeated studies by the present inventors, by using a specific reactant, it is easy to adjust the gel time among water glass-based solution-type injections, and an injection with less outflow of the solution after curing can be obtained. As a result, the present invention has been completed.

The present invention employs the following means in order to solve the above problems.
(1) and A dosage of the alkaline aqueous solution containing an alkali metal silicate, a ground infusate with B agent of an acidic aqueous solution containing sodium water soluble magnesium salt and citric acid and / or potassium citrate, said The alkali metal silicate is sodium silicate, the water-soluble magnesium salt is magnesium sulfate, and in the agent B, the water-soluble magnesium salt is 2.1 to 3.1%, and the sodium citrate and / or potassium citrate is 2.1. ~ 7.5% (However, "sodium bicarbonate and / or potassium bicarbonate 100 parts by weight magnesium sulfate, chloride alone or in mixture (anhydride equivalent) 5-100 parts by weight, citric acid soda salt, potassium salt Or a mixture of 3 to 200 parts by weight of the mixture "), and the solid injection concentration of the B agent is 4.2 to 10.0%.
(2) The ground injecting agent according to (1), comprising 50 to 200 parts of the sodium citrate and / or potassium citrate (hereinafter referred to as carboxylate salt) with respect to 100 parts of the water-soluble magnesium salt.
( 3 ) A ground injection method in which the agent A and the agent B according to (1) or (2) are separately pumped and merged and mixed in the vicinity of the injection port.
( 4 ) The ground injection method according to ( 3 ), wherein a mixing ratio of the agent A and the agent B is 20:80 to 80:20 in volume ratio.
( 5 ) The ground injection method according to ( 3 ) or ( 4 ), wherein the gel time is adjusted by diluting a stock solution of an aqueous solution having a solid content concentration of 30 to 50% of the B agent.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.

  By adopting the ground injecting agent and the ground injecting method using the same of the present invention, the gel time can be easily adjusted, and the effect of reducing the outflow of the solution after curing is achieved.

Hereinafter, the present invention will be described in more detail.
(Alkali metal silicate)
The alkali metal silicate used in the present invention is an aqueous solution of sodium silicate. The alkali metal silicate has a SiO ₂ / R ₂ O molar ratio (R is an alkali metal) of preferably about 2 to 5, and a mixture thereof can also be used. Among these, it is preferable to use a sodium silicate aqueous solution (water glass) that can be obtained at low cost. Among water glasses, JIS No. 3 sodium silicate is more preferable.

  The solid content concentration of the alkali metal silicate solution is preferably 5 to 40 parts, more preferably 10 to 30 parts, in 100 parts of the aqueous solution. If the solid content concentration is low, it may not solidify, and if the solid content concentration is high, the viscosity increases, and the mixing property with the reactant and the pumpability during the injection operation may deteriorate.

(Water-soluble magnesium salt)
The water-soluble magnesium salt used in the present invention is a substance that is acidic by being dissolved in water and supplying magnesium. The water-soluble magnesium salt, in the present invention, that use magnesium sulfate.

  Among the water-soluble magnesium salts, magnesium sulfate is preferable from the viewpoint of reactivity with alkali metal silicate, stability after reaction, and cost. Magnesium sulfate may be anhydrous or have water of crystallization. However, it is preferable to use a material having water of crystallization, which is inexpensive in terms of cost, as a raw material because it dissolves into a solution.

In the present invention, sodium citrate and / or potassium citrate is used as the carboxylate. The carboxylate may be an anhydride or a hydrate.

  The mixing ratio of the carboxylate and the water-soluble magnesium salt is preferably 50 to 200 parts of carboxylate with respect to 100 parts of water-soluble magnesium salt (when water of crystallization is converted as water), 80 to 150 parts. Part is more preferred. If it is the said range, there will be little outflow of the solution after hardening, and a favorable hardening state and moderate viscosity will be obtained.

  In the present invention, each component may be mixed at once, and alkali metal silicate is used as agent A, a mixed solution of water-soluble magnesium salt and carboxylate is used as agent B, and agent A and agent B are mixed. May be used.

  When mixing agent A and agent B, the solid content concentration of agent B is preferably 4 to 50%, more preferably 5 to 25%. Moreover, 3-50% is preferable and, as for the total solid content density | concentration of A agent and B agent, 5-25% is more preferable. If it is the said range, there will be little outflow of the solution after hardening, and a favorable hardening state and moderate viscosity will be obtained.

  The mixing method and the injecting method of the ground injecting agent of the present invention are, for example, a method in which the agent A and the agent B are prepared separately, then they are separately pumped, and both are mixed and reacted before or after injecting the ground. Is mentioned. The mixing ratio of agent A and agent B is preferably 20:80 to 80:20 in volume ratio.

  When preparing the A agent and the B agent separately, the B agent is prepared by mixing and dissolving a predetermined amount of water-soluble magnesium salt, carboxylate and water. From the viewpoint of shortening the dissolution time, it is preferable to dissolve by heating at the time of dissolution. A method of using an aqueous solution having a solid concentration of 30 to 50% and diluting to several to 10 times so as to obtain a predetermined gel time at the use site is preferable.

  The method of using the ground injecting agent includes, for example, a method in which the agent A and the agent B are separately pumped and used by a double infusion pump. In the dual-type pump, the A agent and the B agent are separately pumped in equal volumes, mixed and mixed in the vicinity of the inlet, and then injected into the ground.

  JIS No. 3 sodium silicate was diluted with water to prepare an aqueous solution of pH 13 having a solid concentration of 20%, and this was designated as agent A. On the other hand, magnesium sulfate is used as a water-soluble magnesium salt, and sodium citrate is used as a carboxylate salt. 100 parts of sodium citrate is mixed with 100 parts of magnesium sulfate, and heated to 60 ° C. to obtain a solid content of 50% B A drug stock solution was prepared. This B agent was used by diluting the B agent stock solution at the dilution rate shown in Table 1-1.

  A agent and B agent of each dilution rate were mixed at a volume ratio of 50:50 in a room at 20 ° C. and a relative humidity of 80%, and gel time, gel state, and separated water were evaluated. For comparison, an agent B was prepared using citric acid containing no Group 1A element, and tested in the same manner. The results are also shown in Table 1-2.

<Materials used>
No. 3 sodium silicate: JIS silicic acid No. 3 product, Na ₂ O = 9.4%, SiO ₂ = 28.4%, SiO ₂ / Na ₂ O molar ratio = 3.12
Water-soluble magnesium salt: anhydrous magnesium sulfate, commercially available carboxylate salt: anhydrous sodium citrate, anhydrous potassium citrate, commercially available carboxylic acid for comparison: anhydrous citric acid, commercially available water: tap water

<Evaluation method>
Gel time: After mixing 100 ml of agent A and 100 ml of agent B, the time at the point of time when it thickened significantly and stopped flowing was measured.

Separation water amount: Separation water was collected by decantation after 1 hour from the gel time and weighed.
◎: The amount of separated water is less than 3% of the total weight ○: The amount of separated water is 3% or more and less than 7% △: The amount of separated water is 7% or more

Gel state: It was visually examined whether the agent A and the agent B were uniformly mixed.
○: A uniform gel was obtained. Δ: Mixing of agent A and agent B was insufficient, and the gel state was non-uniform.

As shown in Table 1-2, when citric acid was used, a completely dissolved solution was not obtained due to low solubility, and the gel time was hardly changed even when the dilution rate was changed (Experiment No. 1). -1 to 1-4). In contrast, when sodium citrate or potassium citrate is used, a completely dissolved solution is obtained, and the gel time can be adjusted by the dilution rate (Experiment No. 1-5 to 1- 1). 11). Therefore, it turns out that there exists an effect by using carboxylate containing 1A group elements, such as sodium citrate and potassium citrate, instead of carboxylic acids, such as a citric acid.
In addition, when sodium citrate or potassium citrate is used, a solid state concentration of 4 to 50% and a cured state is good, and an appropriate injection time of gel time is obtained, even when the solid content concentration is high and the gel time is short. By using sodium citrate or potassium citrate, the amount of separated water can be reduced as compared with the case of using citric acid (Experiment No. 1-5 to 1-10).

  Example 1 except that magnesium sulfate was used as the water-soluble magnesium salt, sodium citrate was used as the carboxylate, and B agent was prepared using sodium citrate shown in Table 2 with respect to 2.5 parts of magnesium sulfate. Were tested in the same manner. The results are also shown in Table 2.

  As shown in Table 2, by containing 50 to 200 parts of carboxylate with respect to 100 parts of water-soluble magnesium salt (magnesium sulfate), the amount of separated water is small, the cured state is good, and the gel time is appropriately injected. Even when the content of carboxylate is low and the gel time is short, the amount of separated water can be reduced by using carboxylate compared to the case of using carboxylic acid ( Experiment No.2-2, 1-8, 2-3).

  Use magnesium sulfate as the water-soluble magnesium salt, sodium citrate as the carboxylate, use 100 parts of sodium citrate to 100 parts of magnesium sulfate, and prepare a B agent with a solid content concentration of 50% and dilute 5 times The liquid B agent was adjusted and tested in the same manner as in Example 1 except that the gel time and gel state were measured using the A agent and B agent in the ratios shown in Table 3. The results are also shown in Table 3.

  As shown in Table 3, the gel time can be adjusted and a good cured state can be obtained by changing the mixing ratio of the A agent and the B agent in a volume ratio of 20:80 to 80:20. (Experiment No. 3-2, 1-8, 3-3).

  The ground injection agent and the ground injection method using the same according to the present invention are used, for example, to stabilize ground and ground in tunnel civil engineering and urban civil engineering, etc., and as a safer and better performance injection. Is available.

Claims (5)

An alkaline aqueous solution containing an alkali metal silicate, and a ground injecting agent using an aqueous solution B containing an aqueous solution containing an aqueous magnesium salt and sodium citrate and / or potassium citrate, the alkali metal silicate The salt is sodium silicate, the water-soluble magnesium salt is magnesium sulfate, and in the agent B, the water-soluble magnesium salt is 2.1 to 3.1%, and the sodium citrate and / or potassium citrate is 2.1 to 7.5%. (However, "sodium bicarbonate and / or potassium bicarbonate 100 parts by weight, magnesium sulfate, chloride alone or mixture (anhydride equivalent) 5-100 parts by weight, citric acid soda salt, potassium salt alone or mixture) 3), and the solid content concentration of the B agent is 4.2 to 10.0%.   The ground injection agent according to claim 1, wherein 50 to 200 parts of the sodium citrate and / or potassium citrate is contained with respect to 100 parts of the water-soluble magnesium salt. The ground injection method characterized by pumping A agent and B agent of Claim 1 or 2 separately, and merging and mixing in the injection hole vicinity. The ground injection method according to claim 3 , wherein a mixing ratio of the agent A and the agent B is 20:80 to 80:20 in volume ratio. The ground injection method according to claim 3 or 4 , wherein the gel time is adjusted by diluting a stock solution of an aqueous solution of the B agent having a solid content concentration of 30 to 50%.