JPS59124985A - Pouring grout into ground - Google Patents

Abstract

PURPOSE:To solidify soft ground with high operating efficiency without any detrimental effect upon underground water, by pouring into the ground an acidic water glass grout satisfying specific conditions. CONSTITUTION:The acidic water glass grout to be used has a pH of about 0.5- 4, a value X of 1X10<-3>-1 as shown by the equation and [SiO2] value of 0.66 or higher, wherein [H<+>] is molarity of hydrogen ion; [SiO2] is molarity of silicon dioxide and n is molar ratio of water gass. Gelling time of the grout can be readily controlled by varying the pH within a limited range. For example, a grout having a gelling time of about 25hr before pouring can be gelled within about 2hr after pouring into the ground.

Description

[Detailed Description of the Invention] The present invention uses a non-alkaline silicic acid aqueous solution as the solidification liquid, which injects a solidification liquid into soft or leaky ground to solidify or stop the ground (hereinafter simply referred to as solidification). The present invention relates to a ground press-in method, and more particularly to a method using a non-alkaline silicic acid aqueous solution that exhibits an arbitrary gelation time if the pH value is set to an arbitrary value in the acidic or neutral range.

When gelling water glass is applied to ground injection, the injection liquid must meet the following requirements.

[1] Since it is compatible with the injection method of mixing, injection operation, and penetration into the ground, ■ The time required to reach gelation can range from instantaneous to several hours.

■ Viscosity can be maintained at around several cp to 10 cp.

■ It is possible to accurately control the pH of the injection solution.

[2] Since it can be applied to the purpose of consolidation, ■ - Axial compressive strength of several kg/ca ~], 011/c 1 or more strength j
0 scales that hold the ship ■ Highly durable with no decline in strength over time.

■ Immediately solidifies in water.

Conventionally, as a ground injection method using water glass7, adding a reactive agent to water glass was used.However, this method utilizes the gelation of water glass in an alkaline region. Then, the consolidation strength is determined by several degrees to 10 buildings/
Consolidation strong J more than CRD! In order to obtain i, the water glass concentration must be increased, and as a result the PI (
If it is around 12~1, there will be a problem of making the groundwater alkaline. Furthermore, since unreacted water glass is present in the gel, leaching of unreacted water glass will occur over a long period of time. , the permanence of the solidified body cannot be expected, and there is also the problem that the strength decreases over time. In general, if the acidic reactant aqueous solution is gradually added to the hydraulic lath aqueous solution while stirring the entire solution, it is usually used as a crazy artificial method. At the water glass concentration used, gelation occurs within the alkaline range of the circle (■), and even if an acidic reactant aqueous solution is added until the pH reaches 7 or acidic, the blended liquid remains solid and fluid. In addition, if the water glass concentration is made very dilute, the gelation time can be extended to several tens of minutes, but in this case, the strength of the consolidated sand is greatly reduced and /criN or less.

As a result of various studies, the present inventor added water glass to an aqueous solution of an acidic reactant, mixed it, and removed the alkali in the water glass without causing the silicic acid content in the water glass to precipitate in lumps during mixing, thereby creating a non-alkaline solution. By obtaining a silicic acid aqueous solution, adjusting this non-alkaline silicic acid aqueous solution to a predetermined OPH value in the acidic or neutral range, and applying it to the ground injection method, the above-mentioned drawbacks can be eliminated and all the requirements for the above-mentioned ground injection can be satisfied. The present invention is a further development of this prior invention.

That is, the present invention solves the difficulty of adjusting the gelation time and mixing and dissolving conventional non-alkaline water glass grouts by using acidic water glass that satisfies the following conditions, and improves environmental protection. It also has an excellent press-fitting effect. In the graph of FIG. 1, the thick line indicates the region of the circle-■ value in relation to the gelation time of acidic water glass grout, which is the object of the present invention.

An object of the present invention is to provide a ground injection method that takes a long time to gel the injection liquid.

In order to achieve the above object, according to the present invention, the following (A
) to (q) is characterized by injecting acidic water glass grout into the entire ground.

■ PI-■ value must be within the range of approximately 0.5 to 400
1 cutting O-3〈X≦1.

(C) CSiO2] (7) f direct force' 0.66 or more.

However, [1-I addition is the molar concentration of hydrogen ions [5I
O2] is the molar degree of silicon dioxide, and n is the molar ratio of water glass.

The present invention will be explained in further detail below.

As described in the above-mentioned prior invention, conventional non-alkaline water glass grout is made by first preparing an acidic water glass aqueous solution with a pH of around 0.5 to 3, and then adding water glass or an alkali or alkaline salt to the grout. is added to lower the Pi-I value, orient it in the neutral direction, gelatinize in acidic to neutral conditions, and solidify the ground. In this case, as shown in Figure 1, the neutral region is superior in that it does not change the pH value of groundwater, but it is difficult to penetrate into fine-grained soil because the gelation time is extremely shortened. was a drawback. On the other hand, the method of solidifying in an acidic region makes it possible to obtain high strength with a long gelation time.

However, in this method, in order to shorten the gelation time to an injection time suitable for injection, first the pH is 0.5-5.
The basic idea was to make acidic waterglass adjusted to a pH value within the range of 3, and then add an alkaline additive to it to increase the pH value and shorten the gelation time. However, as shown in Figure 1, the gelation time is measured on a curve with a large slope connecting an upwardly convex inflection point near pH 1 to 2 and a downwardly convex inflection point near pH 8. Since the gelation time has to be adjusted, the gelation time varies greatly depending on the amount of the alkali agent added, making it extremely difficult to adjust the gelation time and blend the gelation time.

In order to solve these problems, the present inventor proposed that by using acidic water glass whose pH value is in an upwardly convex region in the range of 0.5 to 4, the gel could be formed despite considerable changes in the pH value. Since the gelation time hardly changes, adjustment of the gelation time and blending operation become extremely easy, and compared to the gelation time at the time of blending, the prior invention (Japanese Patent Publication No. 57-3)
As described in 0935), the inventor of the earlier application found that the properties of non-alkaline water glass grout as a filler are not determined solely by the composition of the water glass, the a degree, the pH, etc., but are determined by the overall Focusing on the fact that these factors are related to each other, we found that when the value of the factors that are comprehensively related to these is within the range of lXl0-3 or less, it can exhibit extremely excellent properties as an injection agent. ing.

In the above prior invention, the value of X is 1×10
-Results of research focusing on the applicability of areas that were considered unfavorable for injection in cases of 3 or higher.X) I
Table 1 shows that water glass with a molar ratio of 30 can be expected to have a sufficient injection effect under certain conditions in the region of X ], O-3, and that blending and injection operations are very easy. PH when used, [H+], C5iO-2,:
The value of X corresponding to l is displayed as 1. However, the water glass used satisfies the following conditions: SiO3: 29.1% (M = 60) Na20: 10.0% n: 3.0 Specific gravity: 1.4 (20°C) Table 1 below Next, conditions related to the PH value and the X value in the present invention will be explained. In addition, for the concentration of 5i02 to have any value as an injection effect, it is necessary that the strength of the consolidated sand is 1#/Cd or more.For that, [SiO□]>0.
This invention requires CS io2 of 66 or higher:
] Experiment 1 was conducted in order to find out the limit of maintaining the pH value of groundwater in a substantially neutral range even when injecting O acidic water glass grout, which limits the concentration of .

In this case, the idea is to install 10 m x '10 below the groundwater table.
m x 10 m (= 1.03 m), if a solid body is formed in the range of 50 m x 50? ? ? X50m (
= 125X103rr? ) pH of groundwater within the range of
If the value is in the almost neutral range, it is assumed that there is no problem with water quality, and the gel is buried in sand and sand 100 times the volume of the gel, filled with water, and the PH value of each and the PH value of the injected solution are measured. The relationship was investigated 0 [Experiment-1] A gel with a volume of 100 CJ was made by mixing n = 3 water glasses into an aqueous sulfuric acid solution and adding acidic water glasses. This gel is 10t (=100X100C4
) was buried in mountain sand, the mountain sand was soaked with tap water, and the PH value of the water in the mountain sand was examined after - weeks. The pH value of tap water is 6
．． The PI (value?d) of 7 mountain sand was 7.2. The results are shown in Table-2.

Table 2 From Table 2, it can be seen that when the pH is the same, the higher the concentration of 5i02, the closer the groundwater is to neutrality. Also, as the X value decreases, groundwater tends to become more neutral, but if the injected liquid's PE (value is more acidic than 0.4), the groundwater's P[-
(It can be seen that the value is more acidic than 60. Also, the P of the injection liquid
It can be seen that even if the H value is 0.5 or more, the Therefore, when [5I02] is 0.66 or more, if the acidic water glass OPH value is 0.5 or more and the It can be seen that it appears. In this way, the PH value of the underground water quality regulation value can be maintained at a value of 5.8 or more.

Next, the present inventor simultaneously satisfies the following conditions: PH is 0.5 to 4.0, 10°> Regarding acidic water glass liquid, an experiment was conducted to find out the conditions regarding the gelation time to prevent dispersion and deviation of the injection liquid.

The present inventor focused on the fact that gelation occurs faster in the ground when a silicic acid aqueous solution with an acidic PFI value is injected, and investigated the relationship between the gelation time of the injection liquid before injection and the gelation time in the ground. We conducted research to clarify this and obtained results that are extremely useful in practice.

That is, the inventors of the present invention have noticed that it is necessary for the gelation time of the injection solution to be within 2 hours after being injected into the ground in order to avoid dispersion and deviation of the injection solution that takes a long gelation time. The basis for this is as follows.

Inject into the ground from the tip of the inlet pipe, and make a hole in Note 7 with a diameter of υ1.
When an area of m is consolidated, the amount of consolidated soil is j×π×1ki4 m
” is.

Assuming that the porosity of sand at 1 tn' is 04, empirically, when 80% of the pores are filled with the injection liquid and the sand solidifies, t is 4.
m', the injection amount required for A is 4 × 0.4 × O,
8 = 1.28 m! = 1280t, and if the amount of injection per minute is 10t, the injection time to infiltrate the injection liquid into a spherical shape with a radius of 1 m is 1280÷10=128 minutes.

Therefore, if the initially injected injectate loses its fluidity within approximately 2 hours, the injectate will disperse and the diameter will decrease to 2 without deviation.
This results in homogeneous solidification over a certain range of m.

This is an example of the ground that is the target of normal injection, and if a diameter of 2 m can be solidified there, a sufficiently satisfactory effect can be achieved, so the above conditions will satisfy the injection effect in general injection work. This can be seen as a sufficient condition for

As a result of research into the formulation of the acidic water glass mixture to obtain the above gelation time in the ground, the inventor found that if the gelation time of the liquid mixture before injection into the ground is within 5 hours. Use a mixed solution that can gel within about 2 hours after being poured into the ground, or that can solidify within 2 hours by collecting soil from the target ground, leaving it in an almost dry state, and then mixing it with the mixed solution. I found nine good things.

The actual experimental results are shown below.

Experiment-2 Plug the bottom end of a vinyl pipe with a cross-sectional area of 10 crA with a stopper.
The bottom 1m length was filled with sand from Chiba Prefecture. Sand porosity is 4
0%, and the gap filling rate of the injection liquid is 80%.
l0X100X O,4X O,8=320cA,
A blended solution with a porosity of -04° and a gap filling ratio of 0.8) was poured into the container.

Based on Table 2, the blended liquids were prepared with gelation times shown in Table 3 below.

Table 3 Seven samples of the above-mentioned vinyl tubes filled with sand were prepared, and the above-mentioned liquid mixture was poured into them. After 120 minutes, the stopper at the bottom end of the vinyl tube was removed, and it was examined whether the injected liquid would flow down or not. 5. “
In cases No. 6 and No. 8, the mixed solution flowed down without gelling together with the sand. Also, the upper part of Na 9 was not gelled (
After 200 minutes, it turned into a gel), and it was found that the lower part had turned into a gel. ]% 7.10, 11, both the upper and lower parts gelled, and the mixed solution did not flow down. As a result, when the injected solution with a gelation time of 5 hours was injected into the ground, it gelled during the injecting process. It was found that fluidity was accelerated and fluidity was lost within about 2 hours.

Experiment 3 Sand mixed with shellfish from Tokyo Groove was air-dried and mixed with the tooth in Table 3 and the blended solution in Table 6. It gelled in 60 minutes. The OPH value of this sand is 8.5. Similarly, when mixed with Chiba beach sand (PH8.1), it gelated in 110 minutes.

Sediment (P) collected from the sandy ground injected with cement H
When mixed with H9,4), it gelated in 10 minutes. When a test similar to Experiment 2 was conducted using these samples, both the upper and lower parts were gelled after 120 minutes, and the blended liquid did not flow down.

From these experiments, even if the gelation time of the compounded solution is 5 hours or more, if the compounded solution is mixed with a dry sample of the ground to be injected and gels within 120 minutes, it will take 120 minutes when injected into the ground. It was found that gelation occurred within a few days.

An acidic solution is prepared using concentrated sulfuric acid as an acidic reactant, and a non-alkaline silicic acid aqueous solution is prepared by mixing an aqueous solution of n=3 water glass without rapid stirring.

An experimental example of the relationship between the ratio of sulfuric acid (98%) and water glass (undiluted solution) and the PH value of a non-alkaline silicic acid aqueous solution is approximately as follows.

In this way, an acidic silicic acid aqueous solution can be prepared.

Experiment 4 Using this, trends in gelation time were investigated when the X value was greater than or less than 1 o -3.

An example is shown below.

[8i02)=1.36 PH=I X=3.97
PH using the mixed solution of X10-2 and NaHCOs.
The gelation time was adjusted by varying the value. Table 4 shows the results.
Shown below.

Table-4 Next (8i02) = 1.36 PH = 3.0X =
3.97 X to-' mixed solution (+) NaHC
The gelation time was adjusted by varying the pH value using Os.

The results are shown in Table-5.

Table 5 In the above example, when Q X) I On the other hand, in the case of X<lXl0-3, it is found that it is extremely difficult to detect even a slight change in pH.

Experiment 5 By adding a monovalent neutral salt, alkaline earth metal salt, or M salt to an acidic water glass solution, the gelation time can be adjusted without changing the pH value. Also, the strength can be greatly increased. Table 6 shows these experimental examples.

That is, the gelation time can be controlled while keeping it in the upwardly convex curve region of PH region X) 10-3, making it easy to adjust the gelation time and perform injection operations. Table 6 Acids used in the acidic liquid in the present invention include sulfuric acid, hydrochloric acid, nitric acid,
Inorganic acids such as phosphoric acid, organic acids such as formic acid, acetic acid, and succinic acid;
Aluminum chloride, aluminum sulfate, monocalcium phosphate, monosodium phosphate, sodium hydrogen sulfate l) Acidic salts such as rum, aluminum sulfate, aluminum chloride; Presence of alkali such as esters, amides, aldehydes such as glyoxal, etc. These include, but are not limited to, substances that can be hydrolyzed to produce acid groups under conditions such as carbon dioxide, and substances whose aqueous solutions exhibit acidity, such as carbon dioxide gas. However, strong acids are the most economical.

As the pH adjuster, a compound exhibiting acidity or alkalinity can be used. In addition to the acids shown in the examples above, non-alkaline silicic acid aqueous solutions can be used as acidic compounds, but for fine adjustment of pH, weak acids such as phosphoric acid, sodium phosphoric acid, hydrogen sulfate, etc. can be used. Acidic salts such as sodium and non-alkaline silicic acid aqueous solutions are suitable.

Compounds that exhibit alkalinity include caustic soda, alkali sodium carbonate such as slaked lime, sodium bicarbonate,
Examples include basic salts such as disodium phosphate and thorium aluminate, oxides whose aqueous solution is alkaline such as magnesium oxide and calcium oxide, and compounds whose aqueous solution is alkaline such as pond water glass and cement. Among the above, weakly alkaline compounds such as thorium bicarbonate and disodium phosphate, and water glass aqueous solutions are particularly suitable for fine adjustment of OPH. There is.

In the present invention, any compound can be added as a strength enhancer or a gelling time adjusting agent. For example, chlorides, chlorates, sulfates, aluminum salts, carbonates, bicarbonates,
Bisulfate, bisulfite, silifluoride, silicate, phosphate,
Inorganic salts such as hydrogen phosphate, pyrophosphate, dichromate, permancanate, arbitrary organic salts, alcohols, other metal oxides, slag, fly ash, calcium silicate, cement, clay, etc. However, it goes without saying that these examples are not limiting.

In addition, the water glass in the present invention has a molar ratio n (S
io□/M20): Any liquid water glass having a value of 1.5 to 5.0 is used.

It goes without saying that bentonite or any other clay may be mixed into the above-mentioned liquid mixture in any proportion.

Any method can be used to apply the grout using the acidic silicic acid aqueous solution according to the present invention.

For example, when cement grout and grout l-i of the acidic water glass according to the present invention are used together, even if the gelation time of the acidic water glass is very long, the effect of neutralizing the excess alkali in the cement grout , P of acidic water glass
The H value is close to neutral, the gelation time is shortened, and it solidifies rapidly, so even if it is injected into rough ground or ground with flowing groundwater, it will prevent the movement or loss of the lunatic liquid and will keep it within the specified range. It can be made to solidify.

Acidic water glass or a solution containing a gelling accelerator (solution A)
It is also possible to inject the following combinations of the alkaline compound liquid or the gelling promoter (liquid B).

■ Inject A and B in succession (Isuku can be done first)
A method in which the A injection and the B injection are combined, or a method in which the A injection and the B injection are combined and either the A injection and the B injection are performed consecutively (whichever comes first).

■ Method of injecting either A injection or B injection size first, and then injecting the other after a while.

Incidentally, as the cement used in combination in the present invention, it is of course possible to mix portland cement, colloid cement, alumina cement, blast furnace cement, or any of the above-mentioned reactive agents as exemplified as PH adjusters and strength enhancers into the cement mixture. be.

In particular, when an alkaline compound such as soda carbonate is added to the cement grout, the consolidation strength of the mixture of non-alkaline silicic acid aqueous solution and cement grout is significantly increased.

In addition, in the press injection according to the present invention, the mixture is accurately mixed and injected to a predetermined OPH value in a mixer, but of course two pumps are used to add any non-alkaline silicic acid aqueous solution or a gelling promoter to it as liquid A. It is also possible to prepare an aqueous solution to which a strength enhancer has been added, and prepare an aqueous solution of a gelling accelerator as liquid B, and then inject both liquids A and B to meet a predetermined pH value or gelling time. Possible 0 (This method is suitable for injection of non-alkaline silicic acid aqueous solution with short gelation time0)
In addition, any injection tube such as a strainer tube, double tube, or rod can be used as the injection tube, and when injecting liquids A and B together, the injection tube can be used at the tip, end, or middle of the injection tube. ,
In addition, it may be possible to merge the pipes in a pipe system including a mixer before flowing into the injection pump.Also, the injection pressure may be several tens of thousands @ even if the injection pressure is normal pressure.
/ crl~several thousand snakes/cr! Even if injection is performed at a high pressure of several tens of centimeters per cwt to several thousand per centimeter per ctrl, even if injection is performed with a fixed press-fit tube, it is possible to inject while moving it up and down. Alternatively, injection may be performed while rotating.

Example 21 Test injection was carried out in a soil layer below the groundwater table in fine sandy ground in the Tokyo area. As the injection solution, Group 10 in Table 2 was used.

3,000 ml of this mixed solution was injected. Before, during, and after the injection, groundwater was sampled from a test hole 5 m away from the injection point and the pH was measured. The PH measurement results were as follows.

The on-site permeability test result was 6.3 x LO” before injection.
z/4ec, but after injection, K = 5. I
0 showing X 10 cm/set, 1 after completion of injection
After a week, we excavated and found that the diameter was 3 mm, centered around the injection pipe.
0m solidified and 01bo12n? The amount of compacted soil was obtained.

Also, the specimen of the consolidated sample is qu = 8.4 H/c
The unconfined compressive strength of r/L was shown.

Example 2 Test injection was carried out in a silt-mixed fine sand layer interposed with a soft clay layer. N grout was prepared in the same manner as the acidic water glass solution shown in Example 1, and B grout was prepared using 500 # of blast furnace cement, 30 # of bentonite, and 1 layer of sodium carbonate.First, N grout was prepared using a Y-shaped pipe. , B grout were combined in equal amounts and 200 liters were injected, and then 2.0 OOt of N grout solution alone was injected. An excavation survey one week after the injection revealed a soft layer with a lot of clay and silt.
Alternatively, a strong vein-like consolidated layer is formed by the combined liquid of A and B grouts at the boundary between the soil layers, and only the N grout permeates between particles in the fine silt-mixed fine sand layer, and the whole As a result, a strong solid body was formed.

The unconfined compressive strength of the excavated sample is qu = 30 #/al f for the consolidated confluent liquid of A and B grouts, and the unconfined compressive strength of the consolidated soil with N grout is qu = = 5.6.
Showed #/crl.

Example-3 Test injection was carried out in gravel ground with a hydraulic conductivity of approximately 1.8 am/sec. First, % 1,0OO
zAtta! l) Cement milk containing 500# Portland cement was injected into the ground. The next day, water was sampled from the injection point and the pH was measured, showing an OPH value of 9.1. Subsequently, the acidic water glass grout used in Example-1 was injected for 60 minutes. The next day, water was sampled from the injection point and the pH value was measured, and the pH value was 6,00. A week later, an excavation survey revealed that cement had solidified between the coarse soil particles, and that the entire area was solidified by acid water glass without moving from the specified injection depth around the injection pipe. .

[Brief explanation of the drawing]

FIG. 1 shows the T? of acidic water glass grout according to the present invention.
It is a graph which shows the area|region of I-I value. Patent applicant Reinforced Earth Engineering Co., Ltd. Paper 1 Store M Procedural amendment (Homin) Q3 Waru 2 years 2 Ha? Director General of the Japan Patent Office Yu #7 Yu　Tomo ■, Indication of the case ``Nowa Taku Year Patent Application No. 17 No. 3, Person making the amendment Relationship with the case Patent applicant θH To 1 Kani 47. Envoy (, (1c) ÷ to the platform / friend / friend)' - Procedural amendment a3 Wa 3 Y August/1, Director General of the Patent Office Genius ◇ Mr. Zero Mouth ■, Indication of the case ■ Wa 47 Patent Application No. 2.3, No. 7, No. 2, Name of Invention, Name of the Invention, 1, Page 3, Relationship with the Amendment Case Patent Applicant, Hongo, Bunkyo-ku, Tokyo: 3-15-1 Beautiful evil [to/bao.]
and critical distance 3゜

Claims (1)

[Scope of Claims] 1. A ground injection method characterized by injecting into the ground acidic water glass grout that satisfies the following conditions (k) to (C). (A) The pH value is within the range of about 0.5 to 4.0. 1 xio-3<x≦1. (C) [5iOz] value 0.66 or more. However, 1 [H+] is the molar concentration of hydrogen ions, (Si0
2) is the molar concentration of silicon dioxide, and n is the molar ratio of water glass. 2. The ground injection method according to claim 1, wherein the acidic water grout has a gelling time of 5 hours or less before injection. 3. The ground injection method according to claim 1, wherein the acidic water glass grout gels within 2 hours after being poured into the ground to be poured.