Ground hardening method and method for producing ground injection liquid

Abstract

To improve ground strength when using a non-alkaline injection chemical solution whose gel time is long in a ground hardening method using the non-alkaline injection chemical solution.SOLUTION: A ground hardening method is a method for hardening a ground by injecting a non-alkaline injection chemical solution into the ground. Each of non-alkaline injection chemical solutions are prepared by preparing two or more kinds of non-alkaline injection chemical solutions, followed by mixing with a predetermined diluted water glass solution. Flash setting gel time and slow setting gel time of the non-alkaline injection chemical solutions are controlled by increasing or decreasing an acidic agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention is ground hardening method , especially the ground Injected chemicals In order to strengthen the ground and stop water leakage, chemicals are injected into the ground to harden the ground. Injected chemicals Regarding improvements to. [Background technology]

[0002] Conventionally, the above-mentioned ground hardening method has been carried out by injecting into the ground a grout with a short gel time obtained by mixing a compound liquid containing water glass with a non-alkaline silicic acid aqueous solution with a low pH value (also called a silica sol in the non-alkaline region), and then subsequently injecting into the ground a non-alkaline silicic acid aqueous solution with a long gel time. Examples of prior art include Japanese Patent Laid-Open Publication No. 57-94083 and Japanese Patent Publication No. 2-16352. Furthermore, when injecting equal amounts, the concentration of the diluted water glass mixed with the non-alkaline silicic acid aqueous solution is made higher in the case of a chemical solution with a short gel time, and lower in the case of a chemical solution with a long gel time. (Non-Patent Document 1) [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 57-94083 [Patent Document 2] Tokuhei 2-16352 [Non-patent literature]

[0004] [Non-Patent Document 1] Fuji Chemical Co., Ltd. "SILICA SHOT A" catalogue excerpt Summary of the Invention [Problem to be solved by the invention]

[0005] The following analysis has been carried out by the inventors of the present application. The disclosures of the above prior art documents are incorporated herein by reference.

[0006] Conventionally, when preparing a non-alkaline silicic acid aqueous solution with a long gel time using the double-pipe strainer method, the amount of acid had to be as small as possible, but not less than the amount required to neutralize the sodium oxide in the water glass, in order to minimize excess acid. Therefore, when combining with the water glass aqueous solution, the diluted water glass used to prepare the silicic acid aqueous solution with a long gel time is used to mix it with the silicic acid aqueous solution with a long gel time in the double pipe at the tip to inject a non-alkaline chemical solution with a short gel time, which posed a problem: in order to make the pH of the resulting injection solution medium to weakly alkaline, a smaller amount of water glass aqueous solution had to be injected proportionally than the non-alkaline silicic acid aqueous solution with a long gel time.

[0007] In addition, when using a commercially available general plunger pump to inject an equal amount of water at a ratio of 1:1, the concentration of the diluted water glass that is mixed with the non-alkaline silica aqueous solution is made higher for solutions with a short gel time, and lower for solutions with a long gel time. This results in a problem of a lower silica concentration in the solution with a long gel time, which results in a poor injection effect (especially unconfined compressive strength).

[0008] In one aspect of the present invention, a ground hardening method is provided that contributes to eliminating or alleviating the above problems. method and ground Injected chemicals Other objects in other aspects of the present invention will be apparent from the entire description of the present application. [Means for solving the problem]

[0009] In one aspect of the present invention, a method for hardening ground by injecting a non-alkaline grout into the ground comprises preparing two or more non-alkaline silicate aqueous solutions having different acid concentrations, and mixing the solutions with a predetermined diluted water glass aqueous solution to prepare each non-alkaline grout. method and ground Injected chemicals is provided. More specifically, the present invention relates to a method for hardening ground by injecting a non-alkaline grout into the ground, the method comprising: Predetermined silica concentration and SiO 2 / Na 2 preparing a predetermined diluted water glass aqueous solution (solution A) having a molar ratio of 0 to 10; a step of preparing first and second non-alkaline silicic acid aqueous solutions (instant setting solution B and slow setting solution C) having different acid concentrations for a quick setting gel time and a slow setting gel time, respectively, using the predetermined diluted water glass aqueous solution and an acidic agent; a step of preparing first and second non-alkaline grouting solutions having different quick-setting gel times and slow-setting gel times (wherein the second non-alkaline grouting solution has a silicic acid concentration equal to or higher than that of the first non-alkaline grouting solution) using the first and second non-alkaline silicic acid aqueous solutions (instant-setting solution B, slow-setting solution C) and the predetermined diluted water glass aqueous solution (solution A); and There is provided a method for hardening ground, characterized in that the first and second non-alkaline grout solutions are each injected in two shots. In a second aspect of the present invention, there is provided a method for producing the non-alkaline injection solution according to the first aspect.

[0010] In the present invention, the term "gel time" refers to the gelation time, the term "non-alkaline" refers to a pH of 9.0 or less, and the term "silicic acid concentration" refers to the concentration of silica (SiO2) or silicon dioxide. [Effects of the Invention]

[0011] While maintaining the silicic acid concentration at a predetermined high level, the gel time of the injection solution can be adjusted from instant setting to slow setting. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram schematically illustrating an example of an actual construction method. [Figure 2] 1 is a graph showing the relationship between the amount of sulfuric acid used and the gel time in Example 4. [Figure 3] 1 is a diagram showing the construction method of Non-Patent Document 1. DETAILED DESCRIPTION OF THE INVENTION

[0013] In one embodiment of the present invention, the ground is non-alkaline. Injection A method for hardening the ground by injecting a liquid, characterized in that two or more kinds of non-alkaline silicate aqueous solutions with different acid concentrations are prepared and mixed with a predetermined diluted water glass aqueous solution to prepare each non-alkaline injection liquid. method and ground Injected chemicals is provided.

[0014] Ground hardening method and ground Injected chemicals In the above, each injection liquid can be prepared by mixing two or more kinds of non-alkaline silicic acid aqueous solutions and a predetermined diluted water glass aqueous solution to have the same silicic acid concentration. Ground hardening method and ground Injected chemicals In the above, the gel time (instant setting and slow setting gel time) of the non-alkaline silicic acid aqueous solution having different silicic acid concentrations can be adjusted by increasing or decreasing the amount of acidifying agent. The silicic acid concentration of the non-alkaline silicic acid aqueous solution can be adjusted by the concentration of the predetermined diluted water glass aqueous solution and the amount of the predetermined diluted water glass aqueous solution added. Of the grouting solutions, the silicic acid concentration of the slow-setting grouting solution can be adjusted to be equal to or higher than the silicic acid concentration of the instantaneous-setting grouting solution. The silicic acid concentration of the non-alkaline injection liquids having different gel times can be set to 4.1 to 18.2 w / v %. Ground hardening Method and ground injection solution In this method, an injection solution with a short gelling time obtained by combining a non-alkaline silicic acid aqueous solution and a predetermined diluted water glass aqueous solution can be injected into the ground, and then an injection solution with a long gelling time obtained by combining a non-alkaline silicic acid aqueous solution and a predetermined diluted water glass aqueous solution can be injected into the ground. Ground hardening method and ground Injected chemicals In the above, silica colloid can be blended into the non-alkaline aqueous silicic acid solution. This ground hardening Method and injection solution is appropriate for use in liquefaction prevention works.

[0015] Preferred embodiments for carrying out the invention will be described below by way of example, but the present invention is not limited to these descriptions.

[0016] According to one embodiment of the present invention, a diluted water glass aqueous solution is first prepared from water glass and water, and then this diluted water glass aqueous solution is used to prepare two or more non-alkaline silicic acid aqueous solutions with different acid concentrations: a non-alkaline silicic acid aqueous solution (ST) for chemical solutions with a short gel time, and a non-alkaline silicic acid aqueous solution (LT) for chemical solutions with a longer gel time, which contains a larger amount of acid than the non-alkaline silicic acid aqueous solution (ST) for chemical solutions with a longer gel time.

[0017] Next, a non-alkaline silicate solution (ST) for a chemical solution with a short gelling time and a diluted water glass solution are mixed together to form an injection solution (SW) with a short gelling time, which is then injected into the ground. Subsequently, a non-alkaline silicate solution (LT) for a chemical solution with a long gelling time and a diluted water glass solution are mixed together to form an injection solution (LW) with a long gelling time, which is then injected into the ground.

[0018] Any commercially available water glass can be used to prepare the diluted water glass solution. Normally, old JIS No. 3 water glass is used (JIS K 1408 is now abolished, so it is referred to as old JIS), but any water glass, such as old JIS No. S2, No. 1, or water glass with a high molar ratio of sodium oxide to silicon dioxide, can be used and the amount of acid can be adjusted accordingly.

[0019] Acids such as sulfuric acid, hydrochloric acid, and phosphoric acid can be used to neutralize the alkali in water glass to prepare a non-alkaline aqueous silicate solution, and these acids may be used alone or in combination. The use of a soluble aluminum acid salt in combination can provide buffering properties, stabilizing the gel time and reducing the dissolution of the gelled material by alkali in the ground.

[0020] For chemicals with a short gel time, it is preferable to inject them in two shots, but for chemicals with a long gel time, it is possible to inject them in one, 1.5 or two shots.

[0021] The silicic acid concentration of the non-alkaline silicic acid aqueous solution (ST) for chemicals with a short gel time is 1.5 to 8.2 (w / v%, the same applies hereinafter), preferably 1.8 to 6.6%, and more preferably 2.0 to 4.9%.

[0022] The silicic acid concentration of the non-alkaline silicic acid aqueous solution (LT) for chemicals with a long gel time is 1.2 to 8.2%, preferably 1.5 to 6.6%, and more preferably 2.0 to 4.9%. The silicic acid concentration of the injection solution (SW) with a short gel time is 4.4 to 18.2%, preferably 4.8 to 14.5%, and more preferably 6.0 to 10.9%.

[0023] The silicic acid concentration of the long-gelling-time injection liquid (LW) is 4.1 to 18.2%, preferably 4.5 to 14.5%, and more preferably 6.0 to 10.9%.

[0024] That is, within the above range of silica concentration, the silica concentrations of the chemicals with long gel time and those with short gel time are set to be approximately equal (preferably equal) within a predetermined appropriate range during ground injection. In addition, in order to increase the improvement strength of the injected ground, it is also possible to make the silica concentration of the slow-setting chemical higher than that of the instantaneous setting chemicals, and this method can be applied to a wide range of construction methods.

[0025] If even higher ground strength is required or durability is to be improved, silica colloid can be appropriately blended into the non-alkaline silicic acid aqueous solution as needed. The increase in silicic acid concentration derived from silica colloid (or colloidal silica) is preferably 0.1 to 10 w / v%. Known acidic or alkaline silica colloids can be used as the silica colloid.

[0026] The non-alkaline silicic acid aqueous solution (ST) for use as a chemical solution with a short gel time is preferably basically in an acid-rich state (so-called strong acidity), more preferably below pH 2, and further preferably between pH 1 and 0.

[0027] The non-alkaline silicic acid aqueous solution (LT) for a chemical liquid with a long gel time is preferably in an acid-rich state (so-called strong acidity), more preferably below pH 2, and further preferably between pH 1 and 0.

[0028] The molar ratio (SiO2) / (Na2O) of the diluted water glass aqueous solution is 1.5 to 4.4, preferably 2.5 to 4.0, more preferably 3.0 to 3.9, and the silicic acid (SiO2) concentration is 2.4 to 10.0 (w / v%, the same applies hereinafter), preferably 3.0 to 8.0%, more preferably 4.0 to 6.0%. The molar ratio and silicic acid concentration of the diluted water glass aqueous solution can basically be selected appropriately and as needed within the above-mentioned ranges.

[0029] The pH of the injection liquid is 1.0 to 9.0, preferably 1.6 to 8.6, and more preferably 1.8 to 8.4. The pH of the injection liquid (SW) with a short gel time is 5.8 to 9.0, preferably 7.0 to 8.6, and more preferably 7.4 to 8.4. The pH of the injection liquid (LW) with a long gel time is 1.0 to 5.8, preferably 1.6 to 4.0, and more preferably 1.8 to 3.0.

[0030] The silica concentration of the grouting solution is selected within a predetermined range, taking into consideration the uniaxial compressive strength of the sand gel. The silica concentration of the grouting solution is mainly determined by the silica concentration of a predetermined diluted water glass aqueous solution, and is arbitrarily selected within the above-mentioned range. However, it can also be easily adjusted by the amount of water glass blended during construction.

[0031] The uniaxial compressive strength of Sand Gel is 250 to 750 kN / m in both instantaneous and slow setting. 2 , preferably 350 to 750 kN / m 2 is achieved, and if necessary, a higher unconfined compressive strength can be achieved.

[0032] In these embodiments, the following construction effects are achieved when implemented. A commercially available dual equal-volume plunger pump can be used instead of a special proportional pump (non-alkaline silicate solution: diluted water glass = 2:1 or 3:1). It is possible to use a diluted water glass aqueous solution with a lower silica concentration than the non-alkaline silica aqueous solution used for the proportional pump, which prevents the formation of non-uniform gels in the non-alkaline silica aqueous solution, making it possible to prepare a chemical solution with a higher overall concentration. Even when using a dual equal volume pump, the silica concentration of the chemical solution with a long gel time can be the same as that of the chemical solution with a short gel time, and can also be higher. [Example]

[0033] Further specific examples will be shown below, but the present invention is not limited to these examples.

[0034] Used in the following examples Materials Indicates the fee.

[0035] Materials used Water glass: Aichi Silica Industry Co., Ltd. No. 3 water glass, SiO2 28.96%, Na2O 9.38%, molar ratio (SiO2 / Na2O) 3.18 Sulfuric acid: Toagosei Co., Ltd. 78% sulfuric acid

[0036] Example 1 Add water to 200ml of No. 3 water glass to make diluted water glass solution. (Diluted water glass solution) 1000ml (silicic acid concentration 8.17w / v%) was prepared. Approximately 41.5ml of water was added to 8.5ml of sulfuric acid, and 150ml of diluted water glass was added while stirring to prepare 200ml of non-alkaline silicic acid aqueous solution (acid-rich state) for chemicals with a short gel time. Approximately 39.0ml of water was added to 11.0ml of sulfuric acid, and 150ml of diluted water glass was added while stirring to prepare 200ml of non-alkaline silicic acid aqueous solution (acid-rich state) for chemicals with a long gel time.

[0037] When 100 ml of a non-alkaline silicate solution for pharmaceuticals with a short gelling time was mixed with 100 ml of diluted water glass, it gelled in 4 seconds. After 1 day (24 hours), the unconfined compressive strength of the sand gel was 535 kN / m 2 It was.

[0038] When 100 ml of a non-alkaline silicate solution for chemicals with a long gelling time was mixed with 100 ml of diluted water glass, it gelled in 16 hours (960 minutes). After 28 days (672 hours), the unconfined compressive strength of the sand gel was 429 kN / m 2 It was.

[0039] An example of an actual application method is shown at a 1000x scale in Figure 1. First, liquid A is prepared with 40 L of base agent (water glass) and 160 L of water to obtain 200 L of liquid A (diluted water glass) (Step 1) (hereinafter, "L" stands for liter). Liquid A is used to prepare liquids B and C. That is, 150 L of liquid A is added to a mixture of 8.5 L of sulfuric acid and 41.5 L of water (total 50 L) to obtain liquid B (instant setting) (Step 2).

[0040] Meanwhile, 150 L of Liquid A is added to a mixture of 11.0 L of sulfuric acid and 39.0 L of water (50 L in total) to obtain Liquid C (slow-setting) (Step 3). Then, Liquid B (instant-setting) and Liquid A are first combined, and a chemical with a short gel time (injection chemical) is injected (Step 4). Next, Liquid C (slow-setting) and Liquid A are combined, and a chemical with a long gel time (injection chemical) is injected (Step 5).

[0041] Typically, Step 1 often takes more than five minutes, as an example. The same applies to Steps 2 and 3. Steps 4 and 5, which involve injection, last for, say, one to several minutes (note that the time required for each injection step varies greatly depending on the target ground). Because the quick-setting agent is injected and then immediately switched to slow-setting agent, the preparation of the third step may not be completed in time. Therefore, Step 3 involves adding 150 L of Solution A to a mixture of 11.0 L of sulfuric acid and 39.0 L of water (50 L in total) to obtain Solution C (slow-setting agent). Once these solutions are prepared, injection begins. It is practically desirable to prepare the solutions for Step 1 and other steps continuously as the chemical solution runs low. In other words, in this case, the process can be carried out in a continuous sequence: inject the quick-setting agent for a predetermined time, then inject the slow-setting agent, then pull up the rod, inject the quick-setting agent for a predetermined time, then inject the slow-setting agent, then pull up the rod, inject the quick-setting agent, then inject the slow-setting agent. That is, in the present invention, the preparation of the grouting solution (the preparation of the grouting solution) can be set in accordance with the continuous progress of the grouting process at each construction site, which has the advantage of being highly practical.

[0042] The order of the set of steps 2 and 4 and the set of steps 3 and 5 can be reversed. Also, please note that in the schematic diagram shown in Figure 1, step 1 is shown as being used in common with the set of steps 2 and 4 and the set of steps 3 and 5 for the sake of convenience. Needless to say, in actual construction, step 1 can also be carried out by preparing twice the amount shown in Figure 1 at one time.

[0043] Example 2 Water was added to 250 ml of No. 3 water glass to prepare 1000 ml of diluted water glass solution (silicic acid concentration 10.2 w / v%). Approximately 70.5 ml of water was added to 9.5 ml of sulfuric acid, and 120 ml of diluted water glass solution was mixed while stirring to prepare 200 ml of non-alkaline silicic acid aqueous solution for chemicals with a short gel time. Approximately 66.5 ml of water was added to 13.5 ml of sulfuric acid, and 120 ml of diluted water glass solution was mixed while stirring to prepare 200 ml of non-alkaline silicic acid aqueous solution for chemicals with a long gel time.

[0044] When 100 ml of a non-alkaline silicate solution for chemicals with a short gel time was mixed with 100 ml of diluted water glass, it gelled in 3 seconds. After 1 day (24 hours), the unconfined compressive strength of the sand gel was 736 kN / m 2 It was.

[0045] When 100 ml of a non-alkaline silicate solution for chemicals with a long gelling time was mixed with 100 ml of diluted water glass, the mixture gelled in 10 hours. After 29 days (696 hours), the unconfined compressive strength of the sand gel was 593 kN / m 2 It was.

[0046] Example 3 Water was added to 200 ml of No. 3 water glass to prepare 1,000 ml of diluted water glass solution. Approximately 92.5 ml of water was added to 7.5 ml of sulfuric acid, and 100 ml of diluted water glass solution was mixed while stirring to prepare 200 ml of non-alkaline silicic acid aqueous solution for chemicals with a short gel time. Approximately 90.0 ml of water was added to 9.5 ml of sulfuric acid, and 100 ml of diluted water glass solution was mixed while stirring to prepare 200 ml of non-alkaline silicic acid aqueous solution for chemicals with a long gel time.

[0047] When 100 ml of a non-alkaline silicate solution for chemicals with a short gelling time was mixed with 100 ml of diluted water glass, the mixture gelled in 8 seconds. After 1 day (24 hours), the unconfined compressive strength of the sand gel was 370 kN / m 2 It was.

[0048] When 100 ml of a non-alkaline silicate solution for chemicals with a long gelling time was mixed with 100 ml of diluted water glass, the mixture gelled in 24 hours. After 28 days (672 hours), the unconfined compressive strength of the sand gel was 360 kN / m 2 It was.

[0049] Example 4 Furthermore, under the same conditions as in Example 1, gel time was measured by varying the amount of sulfuric acid used. The relationship between the amount of sulfuric acid used and gel time obtained as a result is shown in Table 1 below and Figure 2. Figure 2 shows that by adjusting the amount of sulfuric acid used, the gel time can be adjusted to any value within the range from 0.1 minutes or less to several thousand minutes or more (i.e., from instant setting to slow setting). In Table 1, the amount of sulfuric acid in the upper row is ml / 200 ml of solution. The lower row shows the gel time (minutes).

[0050] [Table 1] Relationship between amount of sulfuric acid used and gel time TIFF0007751892000001.tif30156

[0051] (Comparison with prior art) In the ground hardening method described in Non-Patent Document 1, chemical solutions with long gel times are applied with a lower silica concentration than chemical solutions with short gel times. The main agent here refers to water glass. As shown in Figure 3, the application method in this document refers to diluted water glass as Liquid B, and Liquid A in this document refers to the non-alkaline silicate aqueous solution common to both chemical solutions with short and long gel times. The non-alkaline silicate aqueous solution in this document and Liquid B (50 L of water glass + 150 L of water) are used to create a fast-setting mix, while Liquid C (40 L of water glass + 160 L of water), prepared separately from the non-alkaline silicate aqueous solution, is used to create a slow-setting mix. The main agent volume for the fast-setting mix is ​​85 liters, while the main agent volume for the slow-setting mix is ​​75 liters. Tracing the origins reveals that the water glass concentrations (amount of main agent) differ between Liquids B and C. The setter for both the fast-setting and slow-setting mixes is sulfuric acid, and equal amounts are used.

[0052] On the other hand, in the application method of Example 1 of the present application shown in Figure 1, the amount of water glass used per 400 L of chemical solution is calculated as 40 L of water glass in 200 L of liquid A (diluted water glass), and 150 L of diluted water glass is used for the instant-setting (liquid B), so liquid B contains (150 / 200) x 40 L of water glass. When liquids A and B are combined, the total volume becomes 400 L, with 40 L + 30 L = 70 L of water glass. On the other hand, when liquids A and C are combined, the total volume becomes 70 L. In other words, the amount of water glass used in the slow-setting process is the same as that used in the instant-setting process, resulting in the same silica concentration. Furthermore, in terms of the amount of sulfuric acid, 8.5 L of liquid B (instant-setting) was used in the second process, while 11.0 L of sulfuric acid was used in the third process (slow-setting). This indicates that the gel time is adjusted by the amount of sulfuric acid added.

[0053] The example shown in Figure 1 is a typical example of achieving the same silica concentration in slow-setting as in flash-setting, and is the simplest practical method, but is shown as a batch system for ease of illustrating the invention. However, the present invention is not limited to this example, and it is clear that it can be practiced with partial modifications based on the basic technical concept of the present invention as needed. As mentioned above, the construction of the present invention can also be carried out in a continuous system, in which case the blending amounts of each starting material (material) can be adjusted by flow rate control.

[0054] The present invention provides at least the following effects based on the above-described embodiments. (1) The gel time of the injection solution can be adjusted from instantaneous setting to slow setting while maintaining the silica concentration at a predetermined high level. (2) Even when using a 1:1 ratio, the grout with a long gel time can use the same amount of water glass as the grout with a short gel time, and the silica concentration of the grout with a long gel time can be made the same as that of the instant setting grout. As a result, the unconfined compressive strength can be maintained at a high level. Furthermore, when higher ground improvement strength is required, slow-setting concrete can be used with a higher silica concentration than instantaneous setting concrete. (3) Instead of an expensive pump for proportional injection, a commercially available inexpensive pump that delivers equal volumes of fluid (for example, a double plunger pump) can be used. (4) The starting materials are basically water glass and an acid such as sulfuric acid, making it simple and environmentally friendly, and highly useful. (5) The injection agents are basically those that become neutral when injected into the ground, and are easy to work with and have excellent environmental protection properties after injection. (6) If necessary, a pH buffer (for both slow-setting and instant-setting) may be used, but its use is not essential. (7) From the viewpoint of higher unconfined compressive strength and long-term stability, silica colloid can be added, but it is not essential, and no special measures are required when using it. (8) It can be advantageously used in liquefaction prevention works, which will greatly contribute to strengthening national security. (9) SiO2, a strength-imparting component, is hardly soluble in the neutral-acidic range, so all the water glass used reacts, resulting in excellent durability and strength, and virtually no re-elution of SiO2.

[0055] [Note] The present invention can be described in the following manner, but is not limited to this, and any combination of these manners is possible.

[0056] (Mode 1) A method for hardening ground by injecting a non-alkaline grout into the ground, comprising preparing two or more non-alkaline silicate aqueous solutions with different acid concentrations, and mixing the solutions with a predetermined diluted water glass aqueous solution to prepare two or more non-alkaline grout solutions with different acid concentrations. method .

[0057] (Mode 2) The ground hardening method according to Mode 1, wherein each injection solution is prepared by mixing two or more kinds of non-alkaline silicic acid aqueous solutions and a predetermined diluted water glass aqueous solution to have an arbitrary silicic acid concentration. Method and ground injection solution .

[0058] (Mode 3) The ground hardening agent according to Mode 1 or 2, wherein the instantaneous gel time and the slow gel time of the non-alkaline grout solution are adjusted by increasing or decreasing the amount of an acidic agent. Method and ground injection solution .

[0059] (Mode 4) The method for soil hardening according to any one of Modes 1 to 3, wherein the silicic acid concentration of the non-alkaline silicic acid aqueous solution is adjusted by the concentration of a predetermined diluted water glass and the amount of diluted water glass added. Method and ground injection solution .

[0060] (Embodiment 5) The method for soil hardening according to any one of embodiments 1 to 4, wherein the silica concentration of the slow-setting grout is adjusted to be equal to or higher than the silica concentration of the instantaneous-setting grout. Method and ground injection solution .

[0061] (Mode 6) The ground hardening method according to any one of Modes 1 to 5, wherein the silica concentration of the non-alkaline injection solution having a different gel time is 4.1 to 18.2 w / v%. Method and ground injection solution .

[0062] (Embodiment 7) The ground hardening method according to any one of embodiments 1 to 6, wherein silica colloid is blended in the non-alkaline silicic acid aqueous solution. Method and ground injection solution .

[0063] (Mode 8) A ground hardening method according to any one of modes 1 to 7, comprising injecting into the ground a grout having a short gelling time obtained by mixing a non-alkaline silicic acid aqueous solution and the predetermined diluted water glass solution, and then injecting into the ground a grout having a long gelling time obtained by mixing a non-alkaline silicic acid aqueous solution and the predetermined diluted water glass solution. method .

[0064] (Embodiment 9) The ground hardening method according to any one of embodiments 1 to 8, used for liquefaction prevention work Method and ground injection solution .

[0065] (Form 10) A non-alkaline ground injection solution, characterized in that two or more types of non-alkaline silicic acid aqueous solutions are prepared and mixed with a predetermined diluted water glass aqueous solution to prepare each non-alkaline ground injection solution.

[0066] (Form 11) A non-alkaline ground injection solution according to Form 10, wherein each injection solution is prepared by mixing two or more of the non-alkaline silicic acid aqueous solutions with a predetermined diluted water glass aqueous solution to obtain a desired silicic acid concentration.

[0067] (Form 12) A non-alkaline grout for ground grouting according to Form 10 or 11, wherein the instantaneous gel time and slow gel time of the non-alkaline grout are adjusted by increasing or decreasing the amount of an acidic agent.

[0068] (Mode 13) The non-alkaline ground grouting solution according to any one of Modes 10 to 12, wherein the silicic acid concentration of the non-alkaline silicic acid aqueous solution is adjusted by the concentration of a predetermined diluted water glass and the amount of the predetermined diluted water glass added.

[0069] (Form 14) A non-alkaline ground grout solution according to any one of Forms 10 to 13, wherein the silica concentration of the slow-setting grout solution is adjusted to be equal to or higher than the silica concentration of the instantaneous-setting grout solution.

[0070] (Form 15) The non-alkaline grout for ground grouting according to any one of Forms 10 to 14, wherein the silicic acid concentration of the non-alkaline grout for ground grouting having different gel times is 4.1 to 18.2 w / v %.

[0071] (Mode 16) The non-alkaline ground grouting solution according to any one of Modes 10 to 15, wherein silica colloid is blended with the non-alkaline aqueous silicic acid solution.

[0072] The disclosures of the above-mentioned patent and non-patent documents are incorporated herein by reference and may be used as the basis or part of the present invention, as necessary. Modifications and adjustments of the embodiments and examples are possible within the scope of the entire disclosure of the present invention (including the claims and drawings), and further based on its basic technical concept. Furthermore, various combinations and selections (or non-selections, as necessary) of the various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) are possible within the scope of the entire disclosure of the present invention. In other words, the present invention naturally includes various modifications and alterations that would be possible by a person skilled in the art in accordance with the entire disclosure and technical concept, including the claims and drawings. Furthermore, with regard to the numerical values ​​and numerical ranges described in this application, any intermediate values, lower values, and smaller ranges are deemed to be included, even if not explicitly stated. Furthermore, the disclosures of the above-cited documents, when used in part or in whole in combination with the disclosures herein as part of the disclosure of the present invention, in accordance with the spirit of the present invention, are also deemed to be included in (belong to) the disclosures of this application.

Claims

1. A method for injecting a non-alkaline grout into ground to harden the ground, comprising the steps of preparing a predetermined diluted water glass aqueous solution having a predetermined silicic acid concentration and a SiO2 / Na2O molar ratio; a step of preparing first and second non-alkaline silicic acid aqueous solutions having different acid concentrations for a quick-setting gel time and a slow-setting gel time using the predetermined diluted water glass aqueous solution and an acidic agent; preparing first and second non-alkaline grouting solutions having different quick-setting gel times and slow-setting gel times from the first and second non-alkaline silicic acid aqueous solutions and the predetermined diluted water glass aqueous solution, respectively (wherein the second non-alkaline grouting solution has a silicic acid concentration equal to or higher than that of the first non-alkaline grouting solution); and A ground hardening method characterized by injecting the first and second non-alkaline grout solutions in two shots each.

2. 2. The ground hardening method according to claim 1, wherein each injection solution is prepared by mixing the first and second non-alkaline silicic acid aqueous solutions with the predetermined diluted water glass aqueous solution, so that the second non-alkaline injection solution has a silicic acid concentration equal to or higher than that of the first non-alkaline injection solution.

3. 2. The ground hardening method according to claim 1, wherein the instantaneous gel time and the slow gel time of the first and second non-alkaline grouting solutions are adjusted by increasing or decreasing the amount of acidifying agent in the first and second non-alkaline silicic acid aqueous solutions to make the pH of the second grouting solution lower than that of the first grouting solution, thereby adjusting the gel time to be longer.

4. 2. The method for hardening ground according to claim 1, wherein the silicic acid concentrations of said first and second non-alkaline silicic acid aqueous solutions are adjusted by the concentration and amount of said predetermined diluted water glass aqueous solution added.

5. 2. The method for hardening ground according to claim 1, wherein the silica concentration of the slow-setting grout is adjusted to be equal to the silica concentration of the instantaneous-setting grout.

6. 2. The method for hardening ground according to claim 1, wherein the silica concentration of the first and second non-alkaline grouting solutions having different gel times is 4.1 to 18.2 w / v%.

7. A ground hardening method as described in claim 1, wherein silica colloid is blended into at least one of the first and second non-alkaline silica aqueous solutions.

8. A ground hardening method as described in claim 1, comprising injecting into the ground an injection liquid having a short gelling time obtained by combining the first non-alkaline silicic acid aqueous solution and the specified diluted water glass aqueous solution, and then injecting into the ground an injection liquid having a long gelling time obtained by combining the second non-alkaline silicic acid aqueous solution and the specified diluted water glass aqueous solution.

9. The ground hardening method according to any one of claims 1 to 8, which is used for liquefaction prevention work.

10. A method for producing a dilute aqueous water glass solution having a predetermined silicic acid concentration and a predetermined SiO 2 / Na 2 O molar ratio, comprising the steps of: a step of preparing first and second non-alkaline silicic acid aqueous solutions having different acid concentrations for a quick-setting gel time and a slow-setting gel time using the predetermined diluted water glass aqueous solution and an acidic agent; preparing first and second non-alkaline grouting solutions having different quick-setting gel times and slow-setting gel times from the first and second non-alkaline silicic acid aqueous solutions and the predetermined diluted water glass aqueous solution, respectively (wherein the second non-alkaline grouting solution has a silicic acid concentration equal to or higher than that of the first non-alkaline grouting solution); and A method for manufacturing a non-alkaline ground grouting solution, characterized in that the first and second non-alkaline grouting solutions are each injected in two shots.

11. 11. The method for producing a non-alkaline ground grout solution according to claim 10, wherein each grout solution is prepared by mixing the first and second non-alkaline silicic acid aqueous solutions with the predetermined diluted water glass aqueous solution, so that the second non-alkaline grout solution has a silicic acid concentration equal to or higher than that of the first non-alkaline grout solution.

12. 11. The method for producing a non-alkaline ground grout solution according to claim 10, wherein the adjustment of the instantaneous gelling time and the slow gelling time of the first and second non-alkaline silicic acid aqueous solutions is performed by increasing or decreasing the amount of acidifying agent in the first and second non-alkaline silicic acid aqueous solutions to make the pH of the second grout solution lower than that of the first grout solution, thereby adjusting the gelling time to be longer.

13. 11. The method for producing a non-alkaline ground grout solution according to claim 10, wherein the silicic acid concentrations of the first and second non-alkaline silicic acid aqueous solutions are adjusted by adjusting the concentration and amount of the predetermined diluted water glass aqueous solution.

14. 11. The method for producing a non-alkaline ground grout solution according to claim 10, wherein the silica concentration of the slow-setting grout solution is adjusted to be equal to the silica concentration of the instant-setting grout solution.

15. The method for producing a non-alkaline ground grout solution according to any one of claims 10 to 14, wherein the silica concentration of the first and second non-alkaline grout solutions having different gel times is 4.1 to 18.2 w / v%.

16. A method for producing a non-alkaline ground injection solution as described in Claim 10, wherein silica colloid is blended with at least one of the first and second non-alkaline silicic acid aqueous solutions.

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