Chemical solution for ground injection, method for producing the same, and ground injection hardening method

Abstract

To provide a chemical solution for ground injection for injecting a chemical solution into ground and hardening the ground, a method for producing the same, and a ground injection hardening method.SOLUTION: A chemical solution for ground injection has a composition of an aqueous solution of a water glass and a soluble alkaline substance as liquid A, and a slag suspension as liquid B, and satisfies the following conditions of (a), (b), and (c): per 1 L of the chemical solution for ground injection, (a) 3.5>[SiO2]>0.3, (b) 2.5>[SiO2] / [Na2O]>1.7 and (c) 5>[CaO]>0.3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] [Description of Related Applications] This application is a divisional application of Japanese Patent Application No. 2023-149791, which is a divisional application of Japanese Patent Application No. 2020-105564 (filed on June 18, 2020). Each of the above applications that is the parent of this application is deemed to be incorporated herein by reference. The present invention relates to a chemical solution for ground injection, a method for producing the same, and a method for hardening ground injection. In order to strengthen and waterproof the ground, a chemical solution is injected into the ground to harden the ground. In particular, chemical solution injection is also performed to prevent ground liquefaction caused by earthquakes.

Background Art

[0002] Conventionally, as ground improvement agents or ground injection hardening methods as described above, there are Patent Document 1 using blast furnace slag and alkali hydroxide, Patent Document 2 using slag as a main component and water glass, Patent Document 3, etc. In addition, there are Patent Document 4 and Patent Document 5 using slag and water glass. Further, there is Patent Document 6 that does not use water glass.

[0003] When using water glass with a normal molar ratio, a long gel time in units of time such as for preventing liquefaction cannot be obtained. Therefore, in Patent Document 3, the molar ratio of SiO2 / Na2O is 1.45 or less, and one or more gelation retardants selected from the group consisting of sodium carbonate, sodium bicarbonate, and sodium phosphate are added as retardants.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0005] The disclosure content of the above prior art documents is incorporated herein by reference. The following analysis was made by the present inventor. For example, in Patent Document 4, a gelling time of 10 to 35 minutes using sodium aluminate or 33 to 57 minutes using sodium bicarbonate in addition to sodium aluminate is shown as an example. However, sodium aluminate was designated as a controlled drug in 2019, and there is a problem that it cannot be used even in small amounts.

[0006] In Patent Document 3, the above-mentioned retarder, particularly sodium bicarbonate, is effective in delaying the gel time when mixed with a water glass diluent immediately after being mixed with water and slag. However, as time passes after mixing, the retarder reacts with the slag, which is Solution B, and the gel time when mixed with water glass, which is Solution A, is delayed, and it does not harden after several hours of standing of Solution B. Therefore, there is a problem that the mixing and injection with Solution A must be completed promptly after the preparation of Solution B.

[0007] In addition, Patent Documents 4, 5, etc. disclose compositions comprising water glass, slag, and an alkali aluminate as a gelling time adjuster. However, as described above, sodium aluminate has been designated as a controlled drug and cannot be used.

[0008] Therefore, in Patent Document 6, without using water glass, the latent hydraulicity of slag is stimulated with slaked lime to obtain a long gel time. However, since water glass is not used, the viscosity rise is extremely poor, the gel time is unstable, and there are practical problems. In addition, although fine-particle slaked lime on the micron order equivalent to slag is used, slaked lime has very strong cohesiveness and cannot be completely dispersed even with the use of a surfactant. As a result, there is a problem that it causes penetration inhibition and cannot penetrate into fine sand.

[0009] For the injection chemical solution using water glass, slag, and alkali aluminate as an alkali agent, sodium aluminate became a designated dangerous drug in 2019 and cannot be used. Therefore, there is a demand for a ground injection chemical agent and a ground injection hardening method that have performance equivalent to or better than that without using a dangerous drug.

[0010] In one aspect of the present invention, an object is to provide a ground injection chemical solution that mainly uses slag as a suspended substance and can adjust a long gel time (especially on the order of 1 hour) even when using water glass, and can be used with confidence for preventing liquefaction (that is, without using a dangerous drug). In another aspect of the present invention, an object is to provide a similar ground injection hardening method.

Means for Solving the Problems

[0011] According to a first aspect of the present invention, there is provided a ground injection chemical solution for injecting a chemical solution into the ground to harden the ground. The ground injection chemical solution has a composition of an aqueous solution of water glass and a soluble alkali substance as liquid A and a slag suspension as liquid B, and is characterized by satisfying the following conditions (a), (b), and (c). Per liter of the ground injection chemical solution, (a) 3.5 > [SiO2] > 0.3 (b) 2.8 > [SiO2] / [Na2O] > 1.7 (c) 5 > [CaO] > 0.3 Here, [SiO2] represents the total molar concentration of SiO2 in water glass and SiO2 in soluble alkali substances, [Na2O] represents the molar concentration of Na2O in water glass and the total molar concentration of soluble alkali agents converted to Na2O, and [CaO] represents the molar concentration of CaO in slag, respectively. In a modified aspect of the first perspective, the soluble alkali substance is one or more of crystalline sodium silicate, sodium orthosilicate, sodium sesquisilicate, or caustic alkali. More specifically, the soluble alkali substance is contained in liquid A as a gel time shortening agent, and (b) is 2.5 > [SiO2] / [Na2O] > 1.7.

[0012] In a second perspective of the present invention, there is provided a method for producing a chemical solution for ground injection for injecting a chemical solution into the ground to harden the ground. That is, the method for producing the chemical solution for ground injection is A chemical solution for ground injection having a composition of an aqueous solution of water glass and a soluble alkali substance as liquid A and a slag suspension as liquid B is prepared respectively so as to satisfy the following conditions (a), (b), and (c): Per liter of the chemical solution for ground injection, (a) 3.5 > [SiO2] > 0.3 (b) 2.8 > [SiO2] / [Na2O] > 1.7 (c) 5 > [CaO] > 0.3 Here, [SiO2] represents the total molar concentration of SiO2 in water glass and SiO2 in soluble alkali substances, [Na2O] represents the molar concentration of Na2O in water glass and the total molar concentration of soluble alkali substances converted to Na2O, and [CaO] represents the molar concentration of CaO in slag, respectively. In a modified aspect of the second perspective, the soluble alkali substance is one or more of crystalline sodium silicate, sodium orthosilicate, sodium sesquisilicate, or caustic alkali. More specifically, the soluble alkali substance is contained in liquid A as a gel time shortening agent, and (b) is 2.5 > [SiO2] / [Na2O] > 1.7.

[0013] In a third aspect of the present invention, there is provided a ground injection hardening method for injecting a chemical solution into the ground to harden the ground. The ground injection hardening method includes: preparing a chemical solution for ground injection having a composition of an aqueous solution of water glass and a soluble alkali substance as liquid A and a slag suspension as liquid B so as to satisfy the following conditions (a), (b), and (c): per liter of the chemical solution for ground injection, (a) 3.5 > [SiO2] > 0.3 (b) 2.8 > [SiO2] / [Na2O] > 1.7 (c) 5 > [CaO] > 0.3 where [SiO2] represents the total molar concentration of SiO2 in water glass and SiO2 in the soluble alkali substance, [Na2O] represents the molar concentration of Na2O in water glass and the total molar concentration of the soluble alkali substance converted to Na2O, and [CaO] represents the molar concentration of CaO in the slag, respectively; mixing liquid A and liquid B and injecting the mixture into the ground; and is characterized by including the above steps. In a modified aspect of the third aspect, the soluble alkali substance is one or more of crystalline sodium silicate, sodium orthosilicate, sodium sesquisilicate, or caustic alkali. More specifically, the soluble alkali substance is contained in liquid A as a gel time shortening agent, and (b) is 2.5 > [SiO2] / [Na2O] > 1.7.

Embodiments for Carrying Out the Invention

[0014] Regarding condition (a) where 3.5 > [SiO2] > 0.3 per liter of the chemical solution for ground injection, if the SiO2 molar concentration in one liter of the chemical solution for ground injection is 3.5 or more, the viscosity of liquid B increases, inhibiting good penetration. Also, if it is 0.3 or less, the practical strength cannot be achieved. The SiO2 molar concentration in one liter of the chemical solution for ground injection is preferably 2.5 to 0.7, and more preferably 2.0 to 0.8.

[0015] For condition (b) where 2.8 > [SiO2] / [Na2O] > 1.7, hereinafter, [SiO2] / [Na2O] is also simply referred to as the "molar ratio". When the molar ratio of water glass to the total soluble alkali is 2.8 or more, the slag cannot be stimulated and an increase in strength cannot be expected. Also, when it is 1.7 or less, the gel time tends to be short. The molar ratio is more preferably 2.7 - 1.8, still more preferably 2.5 - 1.8 or further 2.3 - 1.8.

[0016] Condition (c) 5 > [CaO] > 0.3 is the molar concentration of CaO in the slag contained per liter of the ground injection chemical solution. However, when the CaO molar concentration is 5 or more, the viscosity of liquid B increases too much, and when it is 0.3 or less, the strength is as low as that of a solution-type chemical solution, which is not preferable. More preferably, the molar concentration of [CaO] is 4 - 0.5, and still more preferably 3 - 0.7.

[0017] As the water glass used for preparing the aqueous solution of water glass as liquid A, any commercially available water glass can be used as the starting material. Usually, JIS No. 3 water glass is used. However, when water glass with a molar ratio of 2.3 or less is available, the amount of soluble alkali substance added can be reduced, which is economically preferable. Even when using JIS No. 3 water glass, it is adjusted with a soluble alkali substance so as to meet condition (b) before use.

[0018] As liquid A, water glass and one or more of caustic alkalis, crystalline sodium silicate, sodium orthosilicate, or sodium sesquisilicate, which are soluble alkali substances, are used. As the caustic alkali, caustic soda and / or caustic potash, etc. are used. As the crystalline sodium silicate, sodium metasilicate pentahydrate and / or nonahydrate are common, but the anhydride can also be used, and sodium orthosilicate or sodium sesquisilicate can also be used, and mixtures thereof can also be used. The slag suspension as liquid B can be injected in any mixing method of 1 shot, 1.5 shots, or 2 shots. The setting and adjustment of the gel time in time units can be easily set and adjusted by changing the amount of the soluble alkali substance added.

[0019] The slag for preparing the slag suspension as liquid B should preferably be fine so as to sufficiently penetrate into the ground (especially soft ground for preventing liquefaction) or sand layer or gravel layer, and a Blaine value (specific surface area) of 8000 cm 2 / g or more is desirable, 10000 cm 2 / g or more, and further 20000 cm 2 / g to 30000 cm 2 / g or more is preferred. Also, although this chemical solution is mainly used as a slow-setting chemical solution for the time order of infiltration injection, when it is used as an instant-setting chemical solution with a gel time of several seconds to a dozen or so seconds where permeability is not required, it goes without saying that an instant-setting agent such as slaked lime or a gel time shortening agent can be used in combination.

[0020] The gel time in time units can be easily set by changing the addition amount of the soluble alkali substance so that the mixed solution of water glass and alkali substance as liquid A and the slag suspension as liquid B can be injected in any mixing method of 1 shot, 1.5 shots or 2 shots. (For example, refer to Figure 1)

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Examples

[0022] The materials used in the following examples are shown. Materials Used Slag: Fine Ceramist FCR-5A (Blaine value 11000 cm 2 / g, particle size D50 = 3.5 μm, hereinafter referred to as slag A) and Fine Ceramist FCR-B1S (Blaine value 20000 cm 2 / g, particle size D50 = 1.8 μm, hereinafter referred to as slag B) Caustic soda: 48% industrial liquid caustic soda manufactured by Tosoh Corporation Sodium metasilicate nonahydrate: Toyo Silicate Co., Ltd. Water glass: Aichi Silicate Industry Co., Ltd.

Example 1

[0023] 1 g of sodium metasilicate nonahydrate was added to 100 ml of a water glass with a solid content concentration of 41% containing SiO2 at a ratio of 2.15 moles per mole of Na2O, and water was added and diluted and mixed to prepare 200 ml of an aqueous solution of water glass and sodium metasilicate (Solution A). On the other hand, 75 g of slag A and water were added and mixed to prepare 200 ml of a slag suspension (Solution B). 100 ml of Solution A and 100 ml of Solution B were mixed, and Toyoura sand (particle size D50 = 0.2 mm) was filled into a mold of φ35 mm × 100 mm at a relative density Dr = 60%. Then, suction was performed from the upper part of the mold with a vacuum pump, and the chemical solution was infiltrated and injected from the lower part of the mold. The chemical solution overflowed from the upper part within 10 seconds from the start of infiltration injection and was captured by the trap. The uniaxial compressive strength after 28 days was 3 MN / m 2 and the gel time of the chemical solution was 3 hours and 22 minutes. The measurement of the gel time was carried out by putting Solution A and Solution B into a beaker, mixing them, and then continuously stirring with a magnetic stirrer. The time when the water surface stopped was taken as the gel time (the same applies hereinafter).

Example 2

[0024] 1 g of caustic soda was added to 100 ml of a water glass with a solid content concentration of 41% containing SiO2 at a ratio of 2.15 moles per mole of Na2O, and water was added and diluted and mixed to prepare 200 ml of an aqueous solution of water glass and caustic soda (Solution A). On the other hand, 75 g of slag A and water were added and mixed to prepare 200 ml of a slag suspension (Solution B). 100 ml of Solution A and 100 ml of Solution B were mixed, and Toyoura sand was filled into a mold of φ35 mm × 100 mm at a relative density Dr = 60%. Then, suction was performed from the upper part of the mold with a vacuum pump, and the chemical solution was infiltrated and injected from the lower part of the mold. The chemical solution overflowed from the upper part within 10 seconds from the start of infiltration injection and was captured by the trap. The gel time of the chemical solution was 2 hours and 5 minutes.

Example 3

[0025] To 100 ml of No. 3 water glass with a solid content concentration of 38.3% containing SiO2 at a ratio of 3.19 moles per mole of Na2O, 16 g of caustic soda and 2 g of sodium metasilicate nonahydrate were added, water was added and diluted and mixed to prepare 200 ml of an aqueous solution of water glass, caustic soda and sodium metasilicate (Solution A). On the other hand, 75 g of slag A and water were added and mixed to prepare 200 ml of a slag suspension (Solution B). 100 ml of Solution A and 100 ml of Solution B were mixed, Toyoura sand was filled into a mold of φ35 mm × 100 mm at a relative density Dr = 60%, and then suction was performed from the upper part of the mold with a vacuum pump, and the chemical solution was infiltrated and injected from the lower part of the mold. Within 10 seconds from the start of infiltration injection, the chemical solution overflowed from the upper part and was trapped by the trap. The gel time of the chemical solution was 3 hours and 50 minutes.

Example 4

[0026] In the same chemical solution composition as in Example 1, the relationship between the addition amount of sodium metasilicate nonahydrate and the gel time (minutes) was examined. The results are shown in Fig. 1. It can be seen that by adjusting the addition amount of sodium metasilicate, the gel time can be adjusted in the range of 50 minutes to 60 minutes to 250 minutes. In addition, to obtain a shorter or longer gel time, it can be adjusted to a desired value by the molar ratio and concentration of water glass, the selection of soluble alkali substances, the amount ratio, etc.

Example 5

[0027] To 80 ml of water glass with a solid content concentration of 41% containing SiO2 at a ratio of 2.15 moles per mole of Na2O, 1 g of sodium metasilicate nonahydrate was added, water was added and diluted and mixed to prepare 200 ml of an aqueous solution of water glass and sodium metasilicate (Solution A). On the other hand, 50 g of slag B and water were added and mixed to prepare 200 ml of a slag suspension (Solution B). 100 ml of Solution A and 100 ml of Solution B were mixed, Toyoura sand (particle size D50 = 0.2 mm) was filled into a mold of φ35 mm × 100 mm at a relative density Dr = 60%, and then suction was performed from the upper part of the mold with a vacuum pump, and the chemical solution was infiltrated and injected from the lower part of the mold. Within 10 seconds from the start of infiltration injection, the chemical solution overflowed from the upper part and was trapped by the trap. The gel time of the chemical solution was 1 hour and 40 minutes.

Example 6

[0028] In the same chemical solution composition as in Example 5, the relationship between the addition amount of sodium metasilicate nonahydrate and the gel time (minutes) was examined. The results are shown in FIG. 2. It can be seen that by adjusting the addition amount of sodium metasilicate, the gel time can be adjusted in the range of 35 minutes to 60 minutes to 110 minutes. In addition, to obtain a shorter or longer gel time, it can be adjusted to a desired value by the molar ratio and concentration of water glass, the selection of soluble alkali substances, the amount ratio, and the like.

[0029] (Effects of the Invention) According to the present invention, by taking advantage of the properties of slag with low cohesive force as a suspended substance used in the chemical solution for ground injection, the following various effects are achieved, but it does not mean that it is limited thereto. (1) Since a sufficiently long gel time can be ensured, it has excellent permeability and also excellent stability. These points are ensured by not using slaked lime with strong cohesiveness. (2) By changing the addition amount of the soluble alkali substance without using a retarder, a long gel time of 0.5 hours or more to further 1 hour or more to several hours (for example, 4 hours) can be adjusted, so it can also be used for liquefaction prevention work. (3) Cement for stimulating the latent hydraulicity of slag is not required as a suspended substance. Therefore, the chemical solution composition is simple and advantageous in terms of materials. (4) Also, since cement is not required, it is not necessary to add a surfactant for dispersing the suspended substance.

[0030] Note that each disclosure of the above prior art documents is incorporated herein by reference. Within the scope of the entire disclosure of the present invention (including the claims and the drawings), modifications and adjustments of the embodiments or examples can be made based on its basic technical idea. Also, within the scope of the entire disclosure of the present invention, various combinations or selections of various disclosure elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) are possible. That is to say, the present invention naturally includes all disclosures including the claims and the drawings, as well as various deformations and corrections that could be made by those skilled in the art according to the technical idea. Further, regarding the numerical values and numerical ranges described in the present application, even if not explicitly stated, any intermediate value, lower-order numerical value, and small range thereof are considered to be described.

Claims

1. A ground injection liquid for injecting the liquid into the ground to harden the ground, the ground injection liquid having a composition of liquid A being an aqueous solution of water glass and a soluble alkaline substance as a gel time shortening agent, and liquid B being a slag suspension, the ground injection liquid being characterized in that it satisfies the following conditions (a), (b), and (c): Per liter of the ground injection solution, (a)3.5>[SiO ２ ]>0.3 (b)2.5>[SiO ２ ] / [N ２ O]>1.7 (c) 5>[CaO]>0.3 Here, [SiO ２ ] is SiO in water glass ２ Molar concentration of SiO in soluble alkaline substances ２ The total molar concentration of [Na ２ O] is the Na in water glass ２ The molar concentration of O and soluble alkaline substances are Na ２ [CaO] represents the total molar concentration of CaO in the slag, The soluble alkaline material is one or more of crystalline sodium silicate, sodium orthosilicate, sodium sesquisilicate, or caustic alkali.

2. 2. The ground injection solution according to claim 1, wherein the soluble alkaline substance is one or more of crystalline sodium silicate, sodium orthosilicate, and sodium sesquisilicate.

3. The Blaine value of the slag is 8000 cm ２ The ground injection solution according to claim 1 or 2, wherein the viscosity of the solution is 1 / g or more.

4. The ground injection solution according to any one of claims 1 to 3, which is used for preventing liquefaction or for injection into gravel layers.

5. 5. The ground grouting solution according to claim 1, wherein the gelling time is adjustable within a range of 0.5 hours or more or 1 hour or more.

6. A method for producing a chemical for injection into ground to harden the ground, comprising: Prepare a ground injection solution having the composition of liquid A, which is an aqueous solution of water glass and a soluble alkaline substance as a gel time shortening agent, and liquid B, which is a slag suspension, so as to satisfy the following conditions (a), (b), and (c): Per liter of the ground injection solution, (a)3.5>[SiO ２ ]>0.3 (b)2.5>[SiO ２ ] / [N ２ O]>1.7 (c) 5>[CaO]>0.3 Here, [SiO ２ ] is SiO in water glass ２ Molar concentration of SiO in soluble alkaline substances ２ The total molar concentration of [Na ２ O] is the Na in water glass ２ The molar concentration of O and soluble alkaline substances are Na ２ [CaO] represents the total molar concentration of CaO in the slag, The soluble alkaline substance is one or more of crystalline sodium silicate, sodium orthosilicate, sodium sesquisilicate, and caustic alkali. A method for producing a chemical solution for ground injection, comprising the steps of:

7. 7. The method for producing a ground injection solution according to claim 6, wherein the soluble alkaline substance is one or more of crystalline sodium silicate, sodium orthosilicate, and sodium sesquisilicate.

8. The Blaine value of the slag is 8000 cm ２ The method for producing the ground grouting solution according to claim 6 or 7, wherein the grouting agent has a viscosity of 1000:1 or more.

9. The method for producing a ground grout solution according to any one of claims 6 to 8, wherein the gelation time is adjusted to a range of 0.5 hours or more or 1 hour or more.

10. A ground injection hardening method for hardening ground by injecting a chemical solution into the ground, comprising the steps of: A process for preparing a ground injection liquid having a composition of liquid A of water glass and an aqueous solution of a soluble alkaline substance as a gel time shortening agent, and liquid B of a slag suspension, so as to satisfy the following conditions (a), (b), and (c): Per liter of the ground injection solution, (a)3.5>[SiO ２ ]>0.3 (b)2.5>[SiO ２ ] / [N ２ O]>1.7 (c) 5>[CaO]>0.3 Here, [SiO ２ ] is SiO in water glass ２ Molar concentration of SiO in soluble alkaline substances ２ The total molar concentration of [Na ２ O] is the Na in water glass ２ The molar concentration of O and soluble alkaline substances are Na ２ [CaO] represents the total molar concentration of CaO in the slag, The soluble alkaline substance is one or more of crystalline sodium silicate, sodium orthosilicate, sodium sesquisilicate, or caustic alkali; The process of mixing liquid A and liquid B and injecting them into the ground A ground injection hardening method comprising the steps of:

11. 11. The ground injection hardening method according to claim 10, wherein the soluble alkaline substance is one or more of crystalline sodium silicate, sodium orthosilicate, and sodium sesquisilicate.

12. The Blaine value of the slag is 8000 cm ２ The ground injection hardening method according to claim 10 or 11, wherein the viscosity is 100 / g or more.

13. The ground injection hardening method according to any one of claims 10 to 12, which is for injection into liquefaction prevention or gravel layer injection.

14. The ground injection hardening method according to any one of claims 10 to 13, wherein the gelation time is adjusted to a range of 0.5 hours or more or 1 hour or more.

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