JPS60231786A - Pouring grout into ground - Google Patents

Abstract

PURPOSE:To increase the strength of solidified grout without need of adjusting gel time with a pH adjustor, by mixing an aqueous soln. of water glass with an acidic soln. in such a way that the resulting mixt. may be maintained under an excess acid condition before it reaches a pouring pipe and immediately pouring the grout into ground. CONSTITUTION:An aqueous soln. of water glass having an SiO2/M2O molar ratio of 1.5-5.0 and an acidic soln. (e.g. aqueous soln. of sulfuric acid) are fed to a pipe 2 before it reaches a pouring pipe 1 and the mixt. is immediately poured via the pouring pipe 1 into ground for solidification.

Description

[Detailed Description of the Invention] [Technical field to which the invention pertains] The present invention relates to a ground injection method of injecting a consolidating chemical into soft or leaky ground to consolidate or stop water (hereinafter simply referred to as consolidation). In particular, by using a non-alkaline silicic acid aqueous solution as the solidifying chemical solution, the injection process is simplified and
This invention relates to a ground injection method that does not require adjustment of gelation time using an H adjuster (alkaline agent) and has high strength after consolidation.

[Prior art and its problems]

In recent years, a chemical injection method has been widely used in water stoppage construction, etc., and a compound liquid containing water glass grout as a main component is known as a solidifying chemical solution used in this method. The water glass grout is made by mixing water glass with an acidic liquid such as sulfuric acid or an alkali metal salt, but as can be seen from Figure 1, in the injection method using such water glass grout, the mixed liquid The solution gels before the pH reaches the neutral range, making it impossible to inject.

Generally, in order to obtain the consolidation effect that is the purpose of ground injection, it is said that the water glass concentration in water glass grout needs to be at least 10% by weight; Generally, water glass grout is used in a pH range of 9 or higher because it sets instantly at a pH of around 9. Therefore, it is difficult for the equivalent amount of water glass to completely react, resulting in unreacted water glass in the ground. I can't avoid it. (Figure 1 shows the relationship between gelation time and pH of water glass) In recent years,
A ground injection method using a non-alkaline silicic acid aqueous solution as a solidification chemical has been developed.

In this method, water glass is first added and mixed into an acidic liquid, or the acidic liquid and water glass are mixed together until the pH value is 1 to 2.
The first step is to prepare a strongly acidic silicic acid aqueous solution, and then the second step is to add and mix an alkaline agent such as water glass or carbonate as a pH adjuster to this strongly acidic silicic acid aqueous solution, or to adjust the gelation time by combining them. Method 1 involves preparing a desired liquid mixture through two steps and then injecting it.

However, the above construction method has the following disadvantages (A), (B), and (c).

(A) The process is complicated because it requires a first step of preparing a strongly acidic silicic acid aqueous solution and a second step of adding an alkaline agent to this aqueous solution.

(B) In the second step of adding an alkaline agent to the strongly acidic silicic acid aqueous solution, the gelation time varies greatly due to slight differences in the mixture, easily resulting in instant solidification and inhibiting penetration into the ground. This may cause problems such as being exposed.

(C) The strongly acidic silicic acid aqueous solution will be diluted with alkaline solution in the second step, so the final concentration of the mixed solution will be quite low and a high strength solidified body will be formed. can't get it.

[Purpose of the invention]

The purpose of the present invention is to simplify the injection process when injecting a non-alkaline silicic acid aqueous solution, eliminate the need to adjust the gelation time with a pH adjuster, and improve the strength after solidification. The object of the present invention is to provide a ground injection method that improves the drawbacks of the above-mentioned known techniques.

[Key points of the invention]

In order to achieve the above object, the present invention provides a ground injection method in which a water glass aqueous solution and an acidic liquid are jointly injected into the ground through an injection pipe, in which the water glass aqueous solution and the acidic liquid reach the injection pipe. It is characterized in that it is merged at a merging ratio that maintains an excess of acid in the pipes leading up to it, and then immediately injected into the ground through the injection pipe.

[Detailed description of the invention]

In the present invention, the non-alkaline silicic acid aqueous solution is blended in one step rather than in two separate steps as in the conventional method. Therefore, if the blended non-alkaline silicic acid aqueous solution is injected using an injection pump or the like, it will gel on the way, so it is necessary to immediately inject it into the ground as it is. For this purpose, it is necessary that the water glass aqueous solution and the acidic liquid are each introduced separately into a conduit leading to the injection tube, where they are combined at a confluence ratio that maintains an acidic excess. The obtained injection liquid is immediately and easily injected into the ground through the injection pipe. Moreover, once the injection liquid is injected into the ground, the bulky silica becomes difficult to precipitate due to the buffering effect of the soil itself.

In this case, the present invention provides the following (1), (2) and (
3) can be achieved.

(1) The non-alkaline silicic acid aqueous solution is prepared in one step, which simplifies the process. (2) The non-alkaline silicic acid aqueous solution is prepared in a pipe leading to the injection pipe, and this pipe is connected to the injection pipe. Since the aqueous solution is connected to the injection pipe immediately above the ground and is located quite close to the ground, the time required to send the aqueous solution from the pipe into the ground is very short. It is immediately injected directly into the ground through the injection pipe. Therefore, there is no need for the conventional step of preparing a strongly acidic silicic acid aqueous solution and then adjusting the gelation time using an alkaline agent, thereby eliminating this difficulty.

(3) Since the conventional second step can be omitted, the water glass aqueous solution is not diluted by the alkaline agent aqueous solution, and therefore the strength after consolidation is improved.

In addition, in the present invention, it is preferable that the water glass aqueous solution and the acidic liquid are discharged together at a higher pressure than the other in the convergence of the hydroglass aqueous solution and the acidic liquid in the pipe, and in particular, the waterglass aqueous solution has a higher discharge pressure than the acidic liquid. When preparing a non-alkaline silicic acid aqueous solution with a high concentration of water glass, it is more preferable to combine and mix the two.

Furthermore, in the present invention, the merging ratio that maintains excess acid means the electrochemical neutralization point where the merging liquid becomes unstable and the gelation time becomes short, that is, around pH 8.5, preferably around pH 7. This is the merging ratio that always maintains the non-alkaline region on the acidic side.

The present invention will be explained in detail below.

Experiment I Prepare a water glass aqueous solution as liquid A and a sulfuric acid aqueous solution as liquid B, introduce these into a funnel-shaped container equipped with a stirring blade and mix them.
However, the pH value and gelation time were measured. The results are shown in Table-1.

Table 1 In each formulation example in Table 1, a homogeneous gel was formed.

In addition, collect liquid A in a beaker, and add B while stirring.
When the liquid was added and mixed, bulk silica was precipitated.

As mentioned above, if water glass and acidic liquid are combined in a state of excess phosphoric acid, a homogeneous mixed liquid can be obtained, and it can be seen that any p) (value and gelation time can be set) 1, Experiment 2 The following several types The situation of the liquid discharged from the injection tube outlet was investigated using the field test method.

Test method - The same amount of liquid A and liquid B were fed into the pipe line leading to the double injection pipe at the same discharge pressure. The line was connected directly to the injection tube.

Test method-2 Pulp is installed at one entrance of the pipe leading to the double injection pipe so that the discharge pressure from this entrance is higher than the discharge pressure from the other entrance, and A is placed in the pipe. Equal amounts of solution and solution B were each sent and mixed. The difference in the discharge pressure into the pipeline from one inlet and the other inlet is 0 respectively.
．． 9/cA was set for 5, 1.0, and 2.0. The pipe line was placed in direct connection with the injection pipe. To create a difference in discharge pressure, for example, IKpf/i at one inlet
This can be done either by installing a pulp that opens only when a pressure of

Test method-3 A non-alkaline silicic acid aqueous solution was prepared in the same manner as in Experiment 1,
This aqueous solution was pumped into the ground through a 10 m long injection pipe via a plom long hose.

The experimental results are shown in Table-2.

In Table-2, the formulation NIL matches that of Table-1. Also, the 0 mark indicates that a homogeneous gel was formed, the X mark indicates that bulk silica was formed and a heterogeneous gel was formed, and the Δ mark indicates that there was a blockage in the container, injection pipe, hose, or pump. Each represents a different thing.

Table 2 shows that when a mixture of non-alkaline silicic acid aqueous solutions is pumped, it tends to gel or cause bulk silica to precipitate before reaching the injection port.

Furthermore, when the difference in discharge pressure between liquids A and B is zero, bulk silica tends to precipitate when the water glass concentration approaches 40X. In the present invention, it is preferable to have a discharge pressure difference, and in particular, when the water glass liquid is discharged and mixed into the acidic liquid at a higher pressure, a homogeneous mixed liquid can be obtained even if the water glass concentration is high. In the case of , it can be seen that when the discharge pressure is low and the water glass concentration is 40X or more, bulk silica is likely to be precipitated.

Note that although the acidic liquid (acidic reactant) used in the above experiment was sulfuric acid, various other acidic liquids can be used. It is economically advantageous, especially when strong acids are used.

The acidic liquid (acidic reactant) in the present invention is an inorganic acid (sulfuric acid,
Presence of acids such as hydrochloric acid, nitric acid, phosphoric acid, etc.), organic acids (formic acid, acetic acid, etc.), acid salts (monocalcium phosphate, monosodium phosphate, sodium hydrogen sulfate, aluminum sulfate, aluminum chloride, etc.), and alkalis. Refers to substances that generate acid groups when hydrolyzed under conditions of (esters such as polyhydric alcohol acetate, ethylene carbonate, α-butyl lactone, etc.; aldehydes such as glyoxal, etc.; amides such as formamide, etc.).

Although the above examples are shown, it goes without saying that the present invention is not limited to these examples.

Furthermore, in the present invention, a gelling regulator may be added to at least one of the above-mentioned liquid A or liquid B.

As the aforementioned gelation modifier, salts (inorganic salts, organic salts, basic salts, neutral salts, acid salts, etc.), alcohols, alkalis such as caustic soda, etc. can be used, and p reacted with silicic acid can be used. , by changing the pH, or by other chemical or electrochemical actions, forming a silicic acid gel, changing the gelation time, changing the fluidity, or changing the pH by using a pH buffer. It is possible to use a gel that reduces pH fluctuation, or a gel that slows down pH fluctuation, or that increases caking.

An example is shown below.

Inorganic salts: acidic salts, neutral salts, basic salts, etc., calcium chloride, sodium chloride, magnesium chloride,
Chlorides such as potassium chloride and aluminum chloride, sulfates such as calcium sulfate, sodium sulfate and aluminum sulfate, aluminates such as sodium aluminate and potassium aluminate, aluminum salts such as aluminum chloride and aluminum sulfate, ammonium chloride, chloride Zinc, hydrochlorides such as aluminum chloride, chlorates such as sodium chlorate, potassium chlorate, sodium perchlorate, potassium perchlorate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, Carbonates such as ammonium carbonate, calcium carbonate, and magnesium carbonate; bisulfates such as sodium bisulfate, potassium bisulfate, and ammonium bisulfate; bisulfites such as sodium bisulfite, potassium bisulfite, and ammonium bisulfite; Fluorosilicates such as sodium fluorosilicide and potassium fluorosilicide, silicates such as alkali metal salts of silicic acid, alkaline earth metal salts, and aluminum salts, borates such as sodium borate, potassium borate, and ammonium borate, and phosphoric acid. Hydrogen phosphates such as sodium hydrogen phosphate, potassium hydrogen phosphate, ammonium hydrogen phosphate, sodium pyrosulfate,
Throat sulfates such as potassium pyrosulfate and ammonium pyrosulfate; pyrophosphates such as sodium pyrophosphate, potassium pyrophosphate, and ammonium pyrophosphate; dichromates such as sodium dichromate, potassium dichromate, and ammonium dichromate; Permanganates such as potassium permanganate and sodium permanganate.

Alkali: hydroxides of m alkali metals or polyvalent metals such as caustic soda, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or metal oxides such as calcium oxide and magnesium oxide.

Organic salts: Sodium acetate, sodium succinate, potassium formate, sodium formate, etc.

In addition to acting as a pH adjuster or gelling time adjuster, these also have the effect of a strength enhancer.

Furthermore, the above-mentioned acids, acidic silicic acid aqueous solution, and water glass can also be used as pH adjusters. In particular, agents that act as weak alkalinizers are effective in adjusting pH. .

In addition, the water glass in the present invention has a molar ratio n(5i
02/M2O): 1.5-5.0 Alkali metal salt of silicic acid or alkali metal silicic acid in any molar ratio including liquid water glass, anhydrous water glass, hydrous water glass, crystalline water glass, etc. A mixture of salt and silicic acid is used.

Among the gelling modifiers mentioned above, polyvalent metal hydroxides such as magnesium hydroxide and aluminum hydroxide, or polyvalent metal carbonates such as magnesium carbonate and calcium carbonate are poorly soluble; It is excellent as a slow-acting alkaline agent, disodium phosphate is excellent as an alkaline pH buffer that prevents rapid changes in pH, and aluminum sulfate and aluminum chloride are excellent as acidic pH buffers. In addition, polyvalent metal sulfates such as calcium sulfate are poorly soluble and crumble, so they are excellent as slow-acting acids.

Among these, slow-acting alkaline agents and buffering agents that exhibit alkalinity are mixed with water glass, and slow-acting acids and buffering agents that exhibit acidity are mixed with acids to maintain the predetermined gelation time and after gelation. to maintain the pH value in the neutral range,
Alternatively, it is possible to obtain the effect of making it easier to adjust the gelation time by reducing fluctuations in pH.

Application examples of the present invention using slow-acting alkaline agents, PH buffers, etc. will be described below.

In general, in the injection method that gels in the acidic-neutral region, the conventional method uses water glass as the A liquid and an acidic liquid as the B liquid. Or A, 8 so as to always maintain a state of excess acid.
A two-step method involves first creating a strongly acidic silicic acid aqueous solution with a pH of around 1 to 2 while combining the two solutions, and then adding a pH adjuster to this aqueous solution and injecting it to neutralize the pH. It was taken.

As is clear from Figure 1, it is easy to add water glass to an acidic solution to prepare a strongly acidic silicic acid aqueous solution with a pH of 1 to 2, but it is extremely difficult to set the pH value to an intermediate value between 2 and 7. . Therefore, if a slow-acting alkaline agent is mixed into the strongly acidic silicic acid aqueous solution from the beginning, the PH value will be in the neutral range even if the strongly acidic silicic acid aqueous solution is directly injected, making the installation extremely simple. It is estimated.

In the present invention, a slow-acting alkaline agent may be mixed into the water glass in advance. .

In this case, the above-mentioned advantages of the present invention K such advantages Tl), (2
) and (3), since the injected non-alkaline silicic acid aqueous solution automatically moves in the direction of neutralization in the ground, there is an advantage that it further helps prevent pollution. For example, Mg(OH)2
kl (0H)s - A sparingly soluble alkali or salt such as MgCO5 or CaCOs is used.0 Furthermore, in the present invention, a PH buffer may be added to the A solution or the B solution. In this case, even if the merging ratio of solutions A and B varies, the pH does not change significantly due to the action of the pH buffer, so it is possible to obtain a blended solution with a stable desired pH value. Examples of the agent include disodium phosphate b1 aluminum sulfate.

Furthermore, in the present invention, it is also possible to use a slow-acting alkaline agent and a PI (buffer) in combination in liquid A or liquid B. In this case, the pH of the combined liquid A and 8
0 or less, a slow-acting alkaline agent and a pH value that does not change and gradually becomes neutral over time.
An experimental example of the present invention using a buffer will be shown.

Experiment 3 (A) As liquids A and B, the formulations shown in LA in Table 3 were used. Liquid A contains Mg as a slow-acting alkaline agent.
(OH)! was added. This amount of addition is for each sound shown on the horizontal axis of the graph in Figure 2.Liquids A and B are combined in the same manner as in Experiment-1, and the gelation time and PH behavior of the resulting light combined liquid are determined. The results were measured and shown in Figure 2.

(B) As liquids A and B, the formulations shown in &B in Table 3 were used. Liquid A contains 0.42 Mg (OH)!
In addition to this, Na1HPO4 was added as a pH buffering agent.The amounts added are shown on the horizontal axis of the graph in FIG. Liquids A and B were mixed together in the same manner as in Experiment-1, and the gelation time and pH behavior of the resulting combined liquid were measured. The results are shown in Figure 3. The water glass concentration of the OA solution and the acid concentration of the B solution using the formulation shown in Table 3 are the same as those of LA, respectively.
It's rich. Solution A contains Mg (
The OA solution and B solution to which 0H)2 was added in the amounts shown on the horizontal axis of the graph in Figure 4 were combined in the same manner as in Experiment-1, and the gelation time and PH behavior of the resulting combined solution were measured. The results are shown in Figure 4.

(DDA The oA solution using the formulations shown in &D in Table 3 as the A and B solutions contained 0.42 Mg(0H)a.
No. 11, Na1HPO4 was added as a PH buffer, and No. 5
Each amount shown on the horizontal axis of the graph in the figure was added. The water glass concentration of solution A and the acid concentration of solution B are both higher than those of &B. 0 Solutions A and B are combined in the same manner as in Experiment-1, and the gelation time of the resulting combined solution is The behavior of KPH was also measured, and the results are shown in FIG.

@As liquids A and B, the formulations shown in &EK in Table 3 were used. Liquid A contains MgCO as a slow-acting alkaline agent.
5 were added in the amounts shown on the horizontal axis of the graph in FIG. Solution A and Solution B were combined in the same manner as in Experiment-1, and the gelation time and PH behavior of the resulting combined solution were measured.
Shown in the figure.

CF') The formulations shown in &F in Table 3 were used as liquids A and B.
．． Add 6f oMgcos and add 3.5v of 7 to B solution.
5%) 1.804, A & (S
O2)s was added in various amounts shown on the horizontal axis in FIG. The above-mentioned liquid A and liquid B were combined in the same manner as in Experiment-1, and the gelation time and PH behavior of the resulting combined liquid were measured,
The results are shown in Figure 7.

Table 3 As can be seen from Figures 2 to 7 in Experiment 3 above, if a slow-acting alkaline agent is added to Solution A,
-8 The combined liquid exhibits weak acidity with a pH value of 2 to 5 at the time of merging, but after that, it gradually increases and shifts to a neutral direction and becomes a gel, and after gelation, it exhibits a so-neutral region. .

Also, when a PH buffer is added to solution A or solution B, the third
As can be seen from FIG. 5 or 7, the gelation time curve becomes gentler, making it easier to adjust the gelation time.

Incidentally, FIG. 8 shows the change over time in the pH value when a slow-acting alkali agent (slightly soluble alkali agent) is added to the acidic silicic acid aqueous solution. From FIG. 8, it can be seen that when a slow-acting alkali agent is added, the pH value gradually shifts toward neutrality.

FIG. 9 is a graph showing the gradual change in pH of the combined liquid of the water glass aqueous solution and the acidic liquid at the time of confluence and after gelation. 9th
From the figure, it can be seen that the PH value of the combined liquid shows a value of PH 2 to 5 at the time of merging, but shifts to a neutral direction after gelation.

Experiment 4 The unconfined compressive strength of the consolidated standard sand in the construction method of the present invention was tested, and the results are shown in Table 4. In Table 4, test wind 2.3.6
．． Each of samples 7, 10, 11, 14 and 16 had a composition corresponding to the composition style in Table 1, and was tested in Test &1.
Samples 7' to ρ have the formulations numbered 17 to N122 in FIGS. 2 to 7, respectively.

For example, the sample of test air 2 has the composition of mix air 2 in Table 1.
In other words, No. 3 water glass is 19.50 per 50 cc of liquid A.
C, consisting of residual water, 75% sulfuric acid per 50cc of B solution
．． 6CG, consisting of residual water. In addition, the sample of test air 17 has the composition of N&17 in Figure 2, that is, the A liquid is 500%
No. 3 water gage per C x 17.5CG% Mg (0H
) 2 o, rts residual water, consisting of 75X sulfuric acid 3.6CC1 residual water per 50cc of B liquid. The test was conducted by measuring the unconfined compressive strength (H/d) of each sample after 1 day, 7 days, and 4 days of curing.

Table 4 shows that the unconfined compressive strength of the consolidated standard sand of each sample increases as the number of curing days increases and as the water glass concentration increases.

Reference test For comparison with the present invention, each sample shown in Table 5 was prepared, and the unconfined compressive strength of consolidated standard sand was measured for each sample in the same manner as in Experiment 4, and the results are shown in Table 6. It was shown to. Table-5
Each sample NaZ3, 24, 25, 26, 27, 2829
．． 30, the water glass concentration is the same as each sample tooth 2.3.6.7.10.11 and 14.16 in Table 4, but the PH is in the alkaline region 0 Table 5 Table 6 ( Units: kl/evil') From Table 6, it can be seen that in the samples in the alkaline region, even if the water glass concentration becomes high, the unconfined compressive strength of the consolidated standard sand is significantly inferior, and the number of curing days increases. It can also be seen that the -axial compressive strength decreases as the -axial compressive strength decreases0 Furthermore, the method of the present invention can also be applied to the composite injection method.0 The composite injection method is particularly effective for ground with alternating heterogeneous layers. 0 An example of this application will be described below.

First, prepare the following solutions A, B, and C.A solution: water glass aqueous solution B solution: acidic solution C solution: quick-setting agent combination solution (alkaline agent, acid, etc.) and A.
8 Conversion of the permeable secondary grout by the combined liquid can be easily carried out, and this can be carried out by composite injection using the double injection pipe shown in Fig. 11. In other words, first,
) Connected to the double injection tube 1 as shown in 7'C'71
The A liquid and the B liquid are sent to the mixing chamber a formed in the channel 2, and after the two liquids are combined there, the combined liquid is guided to the inner pipe of the double injection pipe 1, and the outer pipe is inserted into the outer pipe. The A-8 combined liquid and C liquid are combined in the mixing chamber a' in the injection pipe 1, and injected into the ground as a quick-setting powder. Fill and solidify the surrounding gaps with the grout. Next, as shown in FIG. 11(b), the feeding of liquid C was stopped and a permeable secondary grout was prepared using the combined liquid A-8, and this was immediately poured into the ground to create an instant-setting grout. In the next step, the thin areas that could not be completely penetrated will be penetrated and solidified.

Construction Example-1 According to Test Method-2 of Experiment-2 above, a water glass aqueous solution was discharged into the mixing section through a valve at a pressure 1 kg/atl higher than the acidic liquid to form a non-alkaline silicic acid aqueous solution, and this aqueous solution was It was injected into homogeneous fine sand ground in the Tokyo area. The compounded solution No. 7 was used for the formulation shown in Table 1.

When 100% of the A-8 combined liquid was injected and an excavation survey was carried out 10 days later, the formation of spherical homogeneous solids of 0.5% was observed. The unconfined compressive strength of the consolidated soil was 11.514/crl0 Construction Example-20 Test method in which injection according to the method of the present invention was carried out into the ground in the Tokyo area where fine sand layers and sand layers are alternately layered. is an example-
It is the same as 1. First, the following A, B, and C solutions were prepared. A solution: Same as the formulation 7 in Table 1. B solution: Same as above C solution Nia 5% sulfuric acid 4.2 CC, water 5! 5.8 CC. The A-8-C combined solution has a pH of 8.5 and a gelation time of 5.
Seconds.

Figure 11 (a) and (b) using the aforementioned solutions A, B, and C.
) The injection was performed according to the injection process.

First, the A-B-C combined liquid is shown in Figure 11 (at 10
After 01 injection, then A-
8 Inject 300 ml of combined liquid and set the injection stage to 50 crn.
This injection was repeated with gradual withdrawal.

An excavation survey was carried out 10 days after the injection, and there was A in the Reki layer.
-B-C combined liquid is mainly filled, and the thin sand layer is filled with A-
8 The combined liquid permeated between the soil particles and solidified homogeneously as a whole. The unconfined compressive strength of the solidified body was 9.5 kg/crA. The hydraulic conductivity test results show that k = 2.
4 x 10-2 to 6.8 x 10-3 cm/se:
However, after injection, k = 3.5 XIO
It was improved to ~2.3X10-6 crn/5ecK.

〔Effect of the invention〕

As described above, when injecting a non-alkaline silicic acid aqueous solution, the present invention combines a water glass aqueous solution and an acidic liquid in a pipe leading to an injection pipe at a confluence ratio that maintains an excess of acid, and then immediately Because it is injected into the ground, the injection process is completed in one step, which simplifies the injection process, eliminates the need to adjust the gelation time using a pH adjuster, and furthermore allows the water glass concentration to be diluted. Therefore, it can be said that this invention is extremely useful in practice.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between pH of water glass and gelation time, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6 and Figure 7 are graphs showing the relationship between pH of water glass and gelation time. These are graphs showing the relationship between gelation time and pH when an acidic silicic acid aqueous solution contains a slow-acting alkali agent or a PH buffer. This is a graph showing the change in pH value over time when the water glass aqueous solution and acidic liquid are combined, and FIG. This is a graph showing an application example of the composite injection method, and is shown in Figure 11 (
At, (b) is a drawing showing an example of construction using the composite injection method. a...mixing chamber, A liquid...water glass solution, B liquid...
...Acidic liquid, C liquid...Accelerating agent combination liquid, 1...Injection pipe, 2...Pipe line. Patent Applicant: Reinforced Soil Engineering Co., Ltd. Paper 1 Note 2 Eyes N2 Marriage θ/A Kai 50- Paper 3 Seedling W Dazzling W 9r Shi A Ne 9-) Paper 9- J'1l (OR) 2 (97A ”;9-50cc) boat 5
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Claims (1)

[Claims] In a ground injection method in which a water glass aqueous solution and an acidic liquid are jointly injected into the ground through an injection pipe, the water glass aqueous solution and the acidic liquid have a confluence ratio such that the water glass solution and the acidic liquid are maintained in an excessively acidic state in the pipeline leading to the injection pipe. A ground injection method characterized in that the mixture is poured into the ground, and then immediately poured into the ground through an injection pipe.