JPS62202113A - Ground grouting work - Google Patents

Abstract

PURPOSE:To form integrated strong ground by a method in which a grout having a poor permeability is first injected and then a water-glass grout having good permeability is injected. CONSTITUTION:The ground is excavated to a given depth by sending boring water from the lower outlet 4 of an inner tube 2. A grout having a poor permeability is injected from an outer tube 1 and then a non-cement reactant-mixed liquid is injected from the upper outlet 3 into the ground. A water glass grout having good permeability, whose pH value is regulated to 9 or move, is then injected from the lower outlet 4 through the inner tube 2 into the ground. The escape of the water glass grout to the outside of the injection range can be prevented, and therefore, uniform ground having excellent durability can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ground injection method using water glass, and particularly to a ground injection method capable of forming an integrated and strong foundation.

[Prior art and its problems]

As a ground injection method using water glass, a method is conventionally known in which cement grout or cement-water glass grout is firstly injected, and then water glass grout is secondarily injected. However, in this method, the primary injection material penetrates only into the coarse parts of the ground and can penetrate into the thin parts, so it can only be used as a rough filling injection to restrain the ground, and fine-grained soil A chemical reaction with the secondary injection material cannot be expected in some parts.

Also known is a construction method in which instant setting grout is injected as a secondary injection material and then slow setting grout is secondly injected. This secondary injection material could be injected in veins into the coarse parts of the soil and penetrated into the finer parts, so that chemical reactions of both grouts in the soil could not be expected.

Furthermore, a method is also known in which a reactive agent is injected into the ground in advance, and then a neutral water glass grout is injected into the injection area. However, in this method, the gelation time of the neutral water glass grout is short, so it is difficult for the grout to penetrate between the soil particles, and therefore, it is difficult for the grout to react with the reactant in the fine-grained soil part of the ground. Improvement of fine-grained soil is insufficient.

Furthermore, there is also known a construction method in which a strainer injection pipe is driven in when water glass is injected, and calcium chloride is injected through the injection pipe while the injection pipe is pulled up to cause the water glass and calcium chloride to react in the ground. However, with this method, highly viscous water glass is pushed outward when calcium chloride is injected, resulting in non-uniform solidification of water glass and calcium chloride in a certain area around the injection pipe.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a ground injection method that forms an integrated, strong foundation and improves the drawbacks of the above-mentioned known techniques.

[Key points of the invention]

In order to achieve the above-mentioned object, according to the present invention, a grout with poor permeability is first injected into the ground, and then a non-cementitious reactant mixture is injected into this injection area, followed by further injection. It is characterized by injecting water glass grout with good permeability and pH of 9 or higher into the area.

[Detailed description of the invention]

The circumstances that led to the completion of the present invention are as follows.

(1) If sand gel solidified with non-cement water glass grout in the alkaline region is immersed in curing water, the silica content of the water glass will leach out over time and its strength will decrease significantly over time. In particular, if the amount of reactant is reduced in order to prolong the gelation time, the product will collapse within several tens of days. However, even with this type of sand gel, no decrease in strength was observed in curing water consisting of an aqueous solution of a non-cement based reactant.
Rather, the strength increases orally.

(2) Even if the above-mentioned sand gel is cured in cement cement or cement-water glass gel, no improvement in strength can be obtained.

(3) Infiltrate a water tank filled with sand with a non-cement reaction agent mixture in advance, and then add non-cement neutral water glass grout and alkaline non-cement water glass grout with a pH of 9 or higher (both of these are the same). - water glass concentration and gel time) were respectively injected at the same injection pressure, and the 21+ permeability range was significantly larger in the latter case.

(4) A non-cement reaction agent mixture was pre-infiltrated into a water tank filled with sand, and then an aqueous water glass solution and an alkaline non-cement water glass grout with a pH of 9 or higher were injected under the same conditions as in (3) above. However, the latter was more homogeneous and had a sufficiently large solidification strength.

(5) Water glass solution and PH in a water tank filled with sand
When 9 or more non-cement water glass grouts were infiltrated and then the reactant aqueous solution was injected before they gelled, a homogeneous solid was not obtained depending on the injection area, and sufficient strength was not obtained. I couldn't.

(6) When a non-cement based reactant mixture solution was infiltrated in advance into a water tank filled with sand, and then a non-cement based water glass grout exhibiting alkalinity with a pH of 9 or higher was injected under the same conditions as above, the result was a homogeneous and The solidified material whose strength over time has been significantly improved is 1).

(7) Cement 1 grout or cement-water glass grout was injected in advance into a water tank filled with sand, and then a non-cement water glass grout exhibiting alkalinity with a pH of 9 or higher was injected under the same conditions as above. No improvement in oral strength of the solids was achieved.

(8) When a non-cement based reactant aqueous solution was infiltrated in advance into a water tank filled with sand, and then cement based grout or cement-water glass grout was injected under the same conditions as above, vein-like solids were formed. However, only sand gel was obtained.

(9) In actual construction, a non-cement reaction agent aqueous solution was injected into the ground consisting of complex alternating layers with different water permeability, and then water glass grout with a pH of 9 or higher was injected, but there was almost no improvement in durability. I couldn't get it.

(Work 0) Inject cement grout, cement-water glass grout, or instant setting water glass grout into the actual ground as the primary injection, then inject the non-cement reactant aqueous solution, and then add water with a pH of 9 or higher. After secondary injection of glass grout, a significant improvement in durability was observed.

Based on the circumstances described in (1) to (10) above, the above-mentioned objects of the present invention are achieved as follows.

(b) - As the next injection, grout with poor permeability is first injected into the ground. This type of grout also includes suspension type grout. This injection first fills the rough areas in the soil, thereby sealing up areas where the grout is likely to deviate and homogenizing the soil.

(b) Next, a non-cement based reactant mixture is injected into the above-mentioned injected area, and is allowed to permeate between the soil particles up to the fine-grained soil portion. Although the non-cement-based reactant mixture has extremely good permeability, the parts that are likely to escape are already confined by the next injection, so the injected reactant mixture is retained without escaping.

(c) As secondary injection, water glass grout with good permeability and a pH of 9 or more is injected overlapping the area into which the reactant mixture has been injected. At this time, the water glass grout pushes out the reactant mixture liquid to the periphery by the injection pressure, replaces it, and permeates between the soil particles. At this time, the periphery of the water glass grout infiltration area is first rapidly gelled by the reactant mixture, then the inside is gelled,
As a result, the solidified portion resulting from the secondary injection is in a state of being penetrated into the reactant mixture. Thereafter, the reactant mixture gradually permeates into the solidified part over time and reacts with unreacted water glass in the solidified part, and all the silica in the water glass precipitates and the reaction progresses. , an increase in strength is achieved.

Further, the reactant mixture also acts on the primary injection material, thereby increasing the strength or improving the durability of the primary injection material, thereby forming a solid foundation that is integrated as a whole.

Hereinafter, the present invention will be specifically explained in detail through experiments.

Experiment-1 The pH and gelation time of the mixed solution of No. 3 water glass and the reactant were measured, and the results are shown in Table-1.

Table-1 (-'yj() Experiment-2 Standard sand was consolidated using the samples of mixed soot 6, io, 13.16, and 23 in Table-1, and the resulting specimen had a diameter of 5 cm.
m, length lOcm) was cured in water ring water lp to measure the SiO□ content in the curing water, thereby measuring the cumulative amount of leached SiOx relative to the amount of S+OZ&8 in the solidification chemical solution, and calculating the leaching rate. Oral changes were investigated. (Table-2) Table-2
The numbers inside are leaching rate (%)/-axial compressive strength (kg/c
ta). Moreover, in Table-2, "-" represents collapse.

Table-2 Experiment-3 20% of aluminum chloride was used as curing water in Experiment-2.
A similar experiment was carried out using the Jukei % solution, and the results are shown in Table 3.

Table 3 Experiment 4 Sand gel (consolidated standard sand) consolidated using formulation N1110 in the same manner as Experiment 2 was cured with 20% by weight solution of various reactants, and after 28 days, SiO□ The leaching rate and strength were measured and the results are shown in Table 4.

Table 4 Experiment 5 100g of Portland cement was mixed into the curing water in the same manner as in Experiment 2, and then the sand gel of composition 1IkllO was cured, and when the unconfined compressive strength was measured after 28 days, it was found to be 1.6 kir/cffl. Ta. This shows that no improvement effect regarding durability can be obtained.

Experiment-6 Using the same method as Experiment-5, gelatinized product 10 of patient 11 was prepared.
0cl11 was crushed and mixed into the curing water. In addition, 100 d of cement-water glass gel was crushed and mixed into the curing water. The composition per 100 ml of gelled cement-water glass is: 25 cc of No. 3 water glass, 50 g of water, and the remainder.

When the unconfined compressive strength of these was measured after 28 days, the blend N11ll showed 1.5 kg/cd, and the cement-water glass gel showed 1.6 kg/ca+! showed that.

None of these had any improvement in durability.

Experiment-7 After saturating the sand in the aquarium with a 20% calcium chloride solution, apply grout of mix level 15.16 with a water head difference of 30 cm? −
2. Injected until it became opaque, and examined the size of the solids one week later. The diameter of the solids was about 20 cm in the case of the mixture No. 15, and about 45 cm in diameter for the case of the combination No. 16.
No. 6 shows a more significant penetration effect.

When a similar experiment was conducted using formulation N1119.20, the diameter of formulation m19 was approximately 15 cm, and the diameter of formulation nozzle 20 was approximately 23 cm.

From the above, it was found that under the same conditions, the permeation range is narrow when the pH is neutral, but the permeation range is extremely wide when the pH is alkaline (9 or higher). This is because the injection liquid is a water glass mixture containing a gelling reactant and has a pH
This is thought to be because when the soil is alkaline, the presence of alkali in the injection liquid slows down the reaction between the reactant in the ground and the injection liquid.

Experiment 8 In the same manner as Experiment 7, a 20% No. 3 water glass solution and a grout with a composition of 11h21 were injected. In the former case, a heterogeneous solid body with a diameter of 10 to 25 cI11 was obtained, whereas in the latter case, a substantially spherical solid body with a diameter of 30 cm was obtained. Further, the unconfined compressive strength of the former was 5 kg/ct, while that of the latter was 9.5 kg/cj.

From the above, it can be seen that it is necessary for the mixed solution to have a pH of 9 or higher during the first night of injection and to contain a gelling reactant in order to achieve homogeneous and firm solidification.

Experiment-9 After saturating the sand in the aquarium with a 20 volume % No. 3 water glass aqueous solution and injecting a 20% calcium chloride solution with a water head difference of 30 clI, the strength of the solids around the injection hole was measured after - weeks. When measured, it showed an unconfined compressive strength of 2 kg/cnl. In the same way, after saturating the sand in the aquarium with the mixed solution in mixing hole 21, a 20% calcium chloride solution was injected before the mixed solution gelled. When the strength was measured, it showed an unconfined compressive strength of 2.6 kg/c11.

If you inject the water glass mixture and then inject the reactant, the reactant will push the water glass mixture outward, causing the water glass concentration around the injection tube to swell and reduce its strength. In the opposite case as in Experiment 8, it can be seen that the reaction agent located around the injection tube gradually permeates into the solidified body formed by the water glass mixture around the injection tube orally, and the reaction progresses.

Experiment 10 Inject 500 cc of cement grout (50 g of cement, 1 remaining water per 100 cc) or cement-water glass grout (same as Experiment 6) into a water tank filled with sand, then add grout with a mixing ratio of 10 to the same area. Inject 1β,
After one week, excavation was carried out, and the unconfined compressive strength was measured 28 days after injection, and the results are shown in Table 5.

Table 5 Table 5 shows that the use of cement grout or cement-water glass grout as the primary injection material does not improve the oral strength of the secondary injection material.

Experiment-11 After saturating the sand in the water tank with a 20% calcium chloride solution, 500 cc of the cement grout and cement-water glass grout from Experiment-1O were injected, and excavation was carried out after - weeks, but the sand had solidified into veins. Only by inter-particle infiltration of the soil, no overall consolidation was obtained. In other words, it was found that such a method does not improve the consolidation effect due to infiltration between soil particles.

Experiment-12 When 51 grams of 20% aluminum chloride solution was injected into the sand in the aquarium, and then 5 grams of water glass grout with a composition of 10 was injected (Experiment-A), and when 51 grams of water glass grout with a composition of 10 was injected into the sand in the aquarium. Afterwards, a comparative experiment was conducted in which 5 ρ of 20% aluminum chloride solution was injected after gelation (Experiment-B).

In addition, when 5p of 20% aluminum chloride solution was injected and then 52p of water glass grout with a formulation of NcL21 was injected (Experiment-C), and after 512p of waterglass grout with a formulation of NcL21 was injected, 20p of water glass grout with a formulation of NcL21 was injected and then 20p was injected before it gelled. A test was also conducted in which 54% aluminum chloride solution was injected (Experiment-D).

7 days, 28 days, and 3 months after injection, we excavated around the injection pipe, collected samples, and measured the unconfined compressive strength and PH.
The results are shown in Table-6.

Table 6 Note: m=qu (kg/cal) From Table 6, it can be seen that the increase in strength over time, that is, durability, has a large relationship with the injection order, the PH1 atmosphere of the solidified material, etc. In other words, when injecting the reactant in advance and then injecting the water glass grout, the polymerization of water glass is promoted in an alkaline atmosphere even if the pH of the reactant is acidic, which improves durability and increases strength. make a big impact.

On the other hand, when water glass grout is injected and then an acidic reactant is injected, the PH value of the solidified material becomes acidic or neutral, and the strength does not increase significantly. For comparison, in Experiment B, the strength was measured for 7 days without injecting the reactant afterwards, and it showed 1°5 on the 26th day. From this, in Experiment B, when water glass grout was injected and the reactant was injected after gelling, the solidified material became a neutral atmosphere, but the solidified material was destroyed, and the broken part was difficult to repair after that. It seems that the strength will be lower.

In addition, in Experiment ○, when the acidic reactant was injected before the water glass grout gelled, the water glass grout was pushed outward and the area around the injection tube was made up mainly of the reactant rather than the water glass grout, making it acidic to medium. This indicates that the atmosphere becomes more stable, making it difficult for hard caking to form around the injection tube.

Experiment-13 Cement grout (same as Experiment-10), cement-water glass grout (same as Experiment-6) as the primary injection material in a water tank filled with sand, mix level 2.11.22 of Table-1. Then, 500 cc of the 20% by weight solution of the reactant shown in Table 4 was injected, and then 1! of the grout of formulation 6.10.13.16.21 in Table 1 was added as a secondary injection material. Unconfined compressive strength Q after -week, 28 days, and 3 months after injection
u (kg/cJ) was measured and the results are shown in Table-7.

Table 7 (7'j) From Table 7, compared to the process of injecting cement suspension, cement-water glass grout, and instant setting grout and then injecting water glass grout, it is clear that the process of injecting water glass grout during It can be seen that when the process of injecting liquid is used in combination, durability is significantly increased and strength is increased.

The non-cement water glass grout with a pH of 9 or more according to the present invention is any liquid water glass with a molar ratio of water glass of 1 to 5, and contains any reactive agent such as an acid, a salt, or an organic reactive agent. The reaction time and pH may be adjusted using alkali or acid.

Further, the non-cement reactant mixture includes acids, acidic salts, organic reactants, salts exhibiting alkalinity (sodium bicarbonate, etc.), and polyvalent metal salts are particularly preferred.

These are specifically Card! z, Mg (1!2, etc.), aluminum salts such as aluminum chloride, polyaluminum chloride, and other iron salts.

Specifically, the construction method of the present invention is carried out using the injection pipe shown in FIGS. 1 and 2.

First, as shown in FIG. 1(a), poling water is sent from the lower outlet 4 of the inner pipe 2 to drill a hole in the ground to a predetermined depth.

Next, as shown in Fig. 1(b), the primary injection material and the reactant mixture are sent from the outer pipe I and injected into the ground from the upper discharge port 3, while the secondary injection material is transferred from the inner pipe. 2 and injecting into the ground from the lower discharge port 4, by moving the injection stage from bottom to top, the reactant mixture and secondary injection material are superimposed and injected into the area where the primary injection material was injected. do.

5 is a metal crown.

Fig. 2 shows another example of an injection pipe, and first, Fig. 2(a)
As shown in , when the reactant mixture is fed from the inner tube 2 and the water glass is fed from the outer tube 1, the valve 7 is displaced downward by the flow pressure of the inner tube 2, opens the upper discharge port 3, and at the same time The discharge port 4 is closed, and the primary injection material is injected into the ground from the upper discharge port 3. Next, as shown in FIG. 2(b), the feeding of the reactant mixture from the inner tube 2 is stopped, and the reactant mixture is fed from the outer tube 1, followed by non-cement water glass with a pH of 9 or more. When the grout (secondary injection material) is fed, the valve 7 is moved upward by the elastic force of the spring 4, and at this time, the upper outlet 3 is closed by the valve 7, and the lower outlet 4 is opened, causing a reaction. The agent combination liquid and the secondary injection material are injected into the ground 1c from the lower discharge 04. Next, by moving the injection stage from the bottom to the - side, the reactant mixture and the secondary injection material are superimposed and injected into the area where the primary injection material has been injected. 6 is a check valve.

Example: Using the apparatus shown in Figure 1 on the ground in the Tokyo area where fine sand and coarse sand layers are alternately layered, the cement shown in Experiment 6 was applied.
After first injecting 20β of water glass grout, CaCL
'z 20% (weight)) 8 liquid as 801/main, then water glass grout with a mixing ratio of 10/100% from the lower discharge port.
1 injection, and this process was repeated while raising the injection tube 50 cm at a time.

The excavation results show that the unconfined compressive strength in the coarse layer is 7.4+r/
The ctA of the thin layer was 3.4 kg/cal, and a homogeneous and scrapable solidified body with excellent durability was obtained.

[Effects of the invention 9 The present invention described above may provide the following effects.

(1) The aging strength of alkaline water glass grout with a long gelation time is greatly improved, and the durability of the solid body is improved.

(2) Obtain a sufficiently wide range of penetration and consolidation effects.

(3) Preventing the secondary injection material from deviating outside the injection range and obtaining a homogeneous solidified body within a predetermined range.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 both show a specific example of an injection pipe for carrying out the construction method of the present invention. 1...Outer pipe, 2...Inner pipe, 3...Upper outlet, 4...Lower outlet, 7...Valve,
3... Hane Patent Applicant Reinforced Soil Engineering Co., Ltd. Representative Patent Attorney Hitoshi Sometani
No. 2 Ile book (no change in content) Arithmetic page 1 (α) (e) Megelunfunun procedural amendment April 9, 1988 Patent application No. 42363 2, title of invention Ground injection method 3, amendment Relationship with the case of the person who filed the patent application Address of the patent applicant: 3-15-1 Hongo, Bunkyo-ku, Tokyo Name of MiEvil Building
Reinforced Earth Engineering Co., Ltd. 4, Agent 6, Number of inventions increased by amendment None 7゜Subject of amendment Description and drawings.

Claims (1)

[Claims] First, a grout with poor permeability is injected into the ground, then a non-cement reaction agent mixture is injected into this injection area, and then a water glass grout with good permeability with a pH of 9 or higher is injected into this injection area. A ground injection method that is characterized by: