Ground hardening method and chemical solution for grouting

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] The present invention relates to a method for hardening ground, and in particular to a chemical injection liquid for ground injection. In order to strengthen the ground or stop water from entering the ground, a chemical injection liquid is injected into the ground to harden the ground. The present invention particularly relates to an improvement in such a chemical injection liquid for ground injection. [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 mixture liquid containing water glass with a non-alkaline silicic acid aqueous solution with a low pH value (also called 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 JP-A-57-94083 and JP-B-2-16352. Also, when injecting equal amounts, the concentration of the diluted water glass that is 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] Excerpt from Fuji Chemical Co., Ltd.'s "SILICA SHOT A" catalog 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, and the contents of the above-mentioned 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 non-alkaline silicic acid aqueous solution had to be prepared with an acid ratio as small as possible, but not less than the amount that neutralizes the sodium oxide in the water glass, in order to minimize excess acid. Therefore, when joining with the water glass aqueous solution, when the diluted water glass used in preparing the silicic acid aqueous solution with a long gel time is used to mix 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, there was a problem that 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 in order to make the pH of the resulting injection chemical medium to weakly alkaline.

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

[0008] In one aspect of the present invention, it is an object of the present invention to provide a ground hardening method and a ground injection liquid that contribute to solving or reducing the above problems. Other objects in other aspects of the present invention will be clearly understood from the entire description of this application. [Means for solving the problem]

[0009] In one aspect of the present invention, there is provided a ground hardening method and a ground injection liquid, which are characterized in that in a method for hardening ground by injecting a non-alkaline injection liquid into the ground, two or more types of non-alkaline silicic acid aqueous solutions having different acid concentrations are prepared, and each non-alkaline injection liquid is prepared by mixing with a predetermined diluted water glass aqueous solution.

[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. Effect 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 instantaneous setting to slow setting. [Brief description of the drawings]

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

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

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

[0015] Preferred embodiments of 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 types of non-alkaline silicic acid aqueous solutions having different acid concentrations, i.e., a non-alkaline silicic acid aqueous solution (ST) for a chemical solution having a short gel time and a non-alkaline silicic acid aqueous solution (LT) for a chemical solution having a long gel time, which contains a larger amount of acid than the non-alkaline silicic acid aqueous solution (ST) for a chemical solution having a long gel time, are prepared.

[0017] Next, the injection liquid with a short gelling time (SW) obtained by combining a non-alkaline silicic acid aqueous solution (ST) for a chemical solution with a short gelling time and a diluted water glass aqueous solution is injected into the ground, and then the injection liquid with a long gelling time (LW) obtained by combining a non-alkaline silicic acid aqueous solution (LT) for a chemical solution with a long gelling time and a diluted water glass aqueous solution is injected into the ground.

[0018] Any commercially available water glass can be used for preparing diluted water glass. Usually, old JIS No. 3 water glass is used (JIS K 1408 is now abolished, so it is indicated as old JIS), but any water glass such as old JIS No. 2, 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.

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

[0020] It is preferable to inject a drug solution with a short gel time in two shots, but a drug solution with a long gel time can be injected in one shot, 1.5 shots, or two shots.

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

[0022] The silicic acid concentration of the non-alkaline aqueous silicic acid solution (LT) for use as a chemical solution having 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 liquid (SW) having 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 injection liquid (LW) having a long gel time 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 concentration of the chemical solution with long gel time and the chemical solution with short gel time are 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 solution higher than that of the instantaneous setting solution, and this can be applied to a wide range of construction methods.

[0025] When higher ground strength is required or when durability is to be improved, silica colloid can be appropriately mixed into the non-alkaline silicic acid aqueous solution as necessary. The increment in silicic acid concentration derived from silica colloid (or colloidal silica) is preferably 0.1 to 10 w / v%. As the silica colloid, known acidic or alkaline silica colloids can be used.

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

[0027] The non-alkaline aqueous silicic acid solution (LT) for use as a chemical solution having a long gel time is preferably in an acid-rich state (so-called strong acidity), more preferably has a pH of less than 2, and further preferably has a pH of 1 or less to 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 below), 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 within the above-mentioned ranges as appropriate and necessary.

[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) having 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) having 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 silicate concentration of the grouting solution is selected within a given range, taking into consideration the uniaxial compressive strength of the sand gel. The silicate concentration of the grouting solution is mainly determined by the silicate concentration of a given diluted water glass aqueous solution, and is selected arbitrarily within the above-mentioned range, but it can also be adjusted by the amount of water glass blended during construction, which is easy.

[0031] The uniaxial compressive strength of sand gel is 250 to 750 kN / m in both the instantaneous and slow setting cases. 2 , preferably 350 to 750 kN / m 2 is achieved, and if necessary, even 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 silicic acid aqueous solution: diluted water glass = 2:1 or 3:1). Since it is possible to use a diluted water glass aqueous solution with a lower silicate concentration than the non-alkaline silicate aqueous solution for the proportional pump, the generation of non-uniform gel of the non-alkaline silicate aqueous solution can be suppressed, 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 with a long gel time can be the same as that of the chemical with a short gel time, and can also be higher. EXAMPLES

[0033] Further specific examples are shown below by way of illustration, but the present invention is not limited to these examples.

[0034] The materials used in the following examples are shown below.

[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 Water was added to 200 ml of No. 3 water glass to prepare 1000 ml of diluted water glass (silicic acid concentration 8.17 w / v%). Approximately 41.5 ml of water was added to 8.5 ml of sulfuric acid, and 150 ml of diluted water glass was mixed while stirring to prepare 200 ml of non-alkaline aqueous silicic acid solution (acid-rich state) for chemicals with short gel times. Approximately 39.0 ml of water was added to 11.0 ml of sulfuric acid, and 150 ml of diluted water glass was mixed while stirring to prepare 200 ml of non-alkaline aqueous silicic acid solution (acid-rich state) for chemicals with long gel times.

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

[0038] When 100ml of a non-alkaline silicate solution for chemicals with a long gelling time was mixed with 100ml 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 429kN / 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 40L of base agent (water glass) and 160L of water to obtain 200L of liquid A (diluted water glass) (first step) (hereinafter, "L" stands for liters). Liquid A is used to prepare liquids B and C. That is, 150L of liquid A is added to a mixture of 8.5L of sulfuric acid and 41.5L of water (total of 50L) to obtain liquid B (instant setting) (second step).

[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 gelling time (chemical to be injected) is injected (step 4). Next, liquid C (slow-setting) and liquid A are combined and a chemical with a long gelling time (chemical to be injected) is injected (step 5).

[0041] In normal cases, for example, the first step often takes more than 5 minutes. The same goes for the second and third steps. The fourth and fifth steps of injection take, for example, 1 to several minutes (note that the time required for each injection step varies greatly depending on the ground to be injected). Since the quick-setting agent is injected and then switched to slow-setting agent immediately, the third step may not be completed in time. Therefore, the third step is to add 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). Injection begins after these solutions are prepared. It is practically desirable to continuously prepare solutions such as the first step when the chemical solution decreases. That is, in this case, the quick-setting agent is injected for a certain time, slow-setting agent is injected, the rod is pulled up, quick-setting agent is injected for a certain time, slow-setting agent is injected, and the rod is pulled up again, quick-setting agent is injected, slow-setting agent is injected. That is, in the present invention, the preparation of the grouting solution (grout preparation) can be set in accordance with the continuous progress of the grouting process at each construction site, and this 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 changed. Also, in the schematic diagram shown in Figure 1, it should be noted that step 1 is described 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 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 short gel times. 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 long gel times.

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

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

[0046] Example 3 Water was added to 200 ml of No. 3 water glass to prepare 1000 ml of diluted water glass. Approximately 92.5 ml of water was added to 7.5 ml of sulfuric acid, and 100 ml of diluted water glass was mixed while stirring to prepare 200 ml of non-alkaline silicic acid aqueous solution for chemicals with short gel times. Approximately 90.0 ml of water was added to 9.5 ml of sulfuric acid, and 100 ml of diluted water glass was mixed while stirring to prepare 200 ml of non-alkaline silicic acid aqueous solution for chemicals with long gel times.

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

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

[0049] Example 4 Furthermore, under the same conditions as in Example 1, the gel time was measured by changing the amount of sulfuric acid used, and the relationship between the amount of sulfuric acid used and the gel time obtained as a result is shown in Table 1 and Figure 2 below. Figure 2 shows that 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) by adjusting the amount of sulfuric acid used. In Table 1, the amount of sulfuric acid in the upper row is ml / 200 ml of chemical solution, and the lower row is the gel time (min).

[0050] [Table 1] Relationship between amount of sulfuric acid used and gel time TIFF2025030364000002.tif17160

[0051] (Comparison with the prior art) In the ground hardening method of Non-Patent Document 1, the chemical solution with a long gel time is applied with a lower silicate concentration than that with a short gel time. The main agent here is water glass. As shown in the application method of Figure 3, in this document, diluted water glass is indicated as Liquid B, and Liquid A in this document is a non-alkaline silicate aqueous solution common to the chemical solutions with a short gel time and the chemical solutions with a long gel time. The non-alkaline silicate aqueous solution in this document and Liquid B (50L water glass + 150L water) are used to obtain a quick-setting mix, and Liquid C (40L water glass + 160L water) prepared separately from the non-alkaline silicate aqueous solution is used to obtain a slow-setting mix. The main agent amount for the quick-setting mix is ​​85L, while the main agent amount for the slow-setting mix is ​​75L. If we trace it back to the origin, we can see that the concentration (main agent amount) of water glass is different between Liquid B and Liquid C. The setter for the quick-setting mix and the slow-setting mix 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 FIG. 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 solution A (diluted water glass), and 150 L of diluted water glass is used for the instant setting (solution B), so solution B contains (150 / 200) x 40 L of water glass. When solution A and solution B are joined, the total volume becomes 400 L, and the amount of water glass is 40 L + 30 L = 70 L. On the other hand, when solution A and solution C are joined, the amount of water glass is also 70 L. That is, in the case of slow setting, the amount of water glass used is the same as that in the case of instant setting, and as a result, the silica concentration is the same. In addition, when the amount of sulfuric acid is considered, solution B (instant setting) in the second process is 8.5 L, while solution C (slow setting) in the third process is 11.0 L of sulfuric acid, and it can be seen that the gel time is adjusted by the amount of sulfuric acid added.

[0053] The example shown in Fig. 1 is a typical example of making the silica concentration the same as that of the instantaneous setting in the case of slow setting, and is the simplest practical method, but is shown as a batch type in consideration of the convenience 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 idea of ​​the present invention as necessary. As mentioned above, the construction of the present invention can also be a continuous type, and in that case, the mixing amount of each starting material (material) can be adjusted by flow control.

[0054] Based on the above-described embodiment, the present invention provides at least the following effects. (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 equal amounts of grout in 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 kept high. In addition, when higher ground improvement strength is required, slow-setting concrete can be applied with a higher silica concentration than the instantaneous setting concrete. (3) Instead of an expensive pump for proportional injection, a commercially available inexpensive pump that delivers equal volumes of liquid (such as a dual plunger pump) can be used. (4) The starting materials are basically water glass and an acid such as sulfuric acid, making the process simple and environmentally friendly, and highly useful. (5) The injection agents used are basically those that become neutral when injected into the ground, and are therefore 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 achieving higher unconfined compressive strength and long-term stability, silica colloid can be added, but this is not essential, and no special measures are required when using it. (8) It can be advantageously used in liquefaction prevention construction, which will greatly contribute to strengthening national safety. (9) SiO2, a strength-imparting component, is hardly soluble in the neutral-acidic region, 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 thereto, and any combination of these manners is possible.

[0056] (Form 1) A method for hardening ground by injecting a non-alkaline injection solution into the ground, characterized in that two or more types of non-alkaline silicate aqueous solutions having different acid concentrations are prepared, and mixed with a predetermined diluted water glass aqueous solution to prepare two or more types of non-alkaline injection solutions having different acid concentrations.

[0057] (Mode 2) A ground hardening method according to Mode 1, in which each injection solution is prepared by mixing two or more kinds of non-alkaline silicic acid aqueous solutions with a predetermined diluted water glass aqueous solution to obtain a desired silicic acid concentration.

[0058] (Mode 3) The method for hardening ground 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.

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

[0060] (Mode 5) A ground hardening method according to any one of Modes 1 to 4, wherein the silicic acid concentration of the slow-setting grout solution is adjusted to be equal to or higher than the silicic acid concentration of the instantaneous-setting grout solution.

[0061] (Mode 6) The ground hardening method according to any one of Modes 1 to 5, wherein the non-alkaline grout solutions having different gel times have a silicic acid concentration of 4.1 to 18.2 w / v %.

[0062] (Mode 7) The ground hardening method according to any one of Modes 1 to 6, wherein silica colloid is mixed with the non-alkaline aqueous silicic acid solution.

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

[0064] (Mode 9) The ground hardening method according to any one of Modes 1 to 8, used for liquefaction prevention work.

[0065] (Form 10) A non-alkaline ground injection liquid, comprising: preparing two or more kinds of non-alkaline silicic acid aqueous solutions; mixing the solutions with a predetermined diluted water glass aqueous solution; and preparing each of the non-alkaline ground injection liquids.

[0066] (Form 11) A non-alkaline ground injection solution according to Form 10, wherein each injection solution is prepared by mixing two or more types of 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 ground grout according to Form 10 or 11, wherein the instantaneous gel time and the 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 grout solution according to any one of Modes 10 to 12, wherein the silicic acid concentration of the non-alkaline aqueous silicic acid 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 silicic acid concentration of the slow-setting grout solution is adjusted to be equal to or higher than the silicic acid concentration of the instantaneous-setting grout solution.

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

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

[0072] The disclosures of the above patent documents and non-patent documents are incorporated herein by reference and may be used as the basis or part of the present invention as necessary. Within the framework of the entire disclosure of the present invention (including the claims and drawings), modifications and adjustments of the forms and embodiments are possible based on the basic technical ideas. Furthermore, within the framework of the entire disclosure of the present invention, various combinations or selections (or non-selection as necessary) of various disclosed elements (including each element of each claim, each element of each form or embodiment, each element of each drawing, etc.) are possible. In other words, the present invention naturally includes various modifications and corrections that a person skilled in the art would be able to make in accordance with the entire disclosure, including the claims and drawings, and the technical ideas. Furthermore, with regard to the numerical values ​​and numerical ranges described in this application, any intermediate value, lower numerical value, and small range are considered to be described even if not specified. Furthermore, the disclosures of the above cited documents may be used in part or in whole in combination with the descriptions in this document as part of the disclosure of the present invention in accordance with the spirit of the present invention as necessary, and are considered to be included (belong) to the disclosures of this application.

Claims

1. A method for hardening ground by injecting a non-alkaline grout into the ground, comprising the steps of: preparing two or more types of non-alkaline silicate aqueous solutions; mixing the solutions with a predetermined diluted water glass aqueous solution; and preparing each of the non-alkaline grout solutions.

2. 2. The method according to claim 1, wherein each of the injection solutions is prepared by mixing two or more kinds of said non-alkaline silicic acid aqueous solutions with a predetermined diluted water glass aqueous solution to obtain a desired silicic acid concentration.

3. 2. The method for hardening ground according to claim 1, wherein the quick-setting gel time and slow-setting gel time of the non-alkaline grouting solution are adjusted by increasing or decreasing the amount of an acidic agent.

4. 2. The method of claim 1, wherein the silicic acid concentration of said 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.

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

6. The method for hardening ground according to claim 1, wherein the silica concentration of the non-alkaline grouting solution with different gel times is 4.1 to 18.2 w / v%.

7. 2. The method for hardening ground according to claim 1, wherein the non-alkaline aqueous silicic acid solution is mixed with silica colloid.

8. 2. The method for hardening ground according to claim 1, comprising the steps of: injecting into the ground an injection liquid having a short gelling time obtained by mixing a non-alkaline silicic acid aqueous solution and the specified diluted water glass solution; and then injecting into the ground an injection liquid having a long gelling time obtained by mixing a non-alkaline silicic acid aqueous solution and the specified diluted water glass solution.

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

10. A non-alkaline ground injection solution comprising: two or more kinds of non-alkaline silicic acid aqueous solutions prepared and mixed with a predetermined diluted water glass aqueous solution to prepare each of the non-alkaline ground injection solutions.

11. 11. The non-alkaline ground injection liquid according to claim 10, wherein each injection liquid is prepared by mixing two or more kinds of non-alkaline silicic acid aqueous solutions with a predetermined diluted water glass aqueous solution to obtain a desired silicic acid concentration.

12. The non-alkaline ground grout solution according to claim 10, wherein the quick-setting gel time and slow-setting gel time of the non-alkaline grout solution are adjusted by increasing or decreasing the amount of an acidic agent.

13. 11. The non-alkaline ground injection solution according to claim 10, wherein the silicic acid concentration of the non-alkaline silicic acid aqueous solution is adjusted by the concentration of the predetermined diluted water glass and the amount of the predetermined diluted water glass added.

14. The non-alkaline ground injection solution according to claim 10, wherein the silicic acid concentration of the slow-setting injection solution is adjusted to be equal to or higher than the silicic acid concentration of the instantaneous setting injection solution.

15. The non-alkaline ground grout solution according to any one of claims 10 to 14, wherein the silicic acid concentration of the non-alkaline grout solution having different gel times is 4.1 to 18.2 w / v%.

16. The non-alkaline ground grout solution according to claim 10, wherein silica colloid is mixed with the non-alkaline aqueous silicic acid solution.

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