JPS5996185A - Pouring of grout into ground - Google Patents

Abstract

PURPOSE:To prevent a grout from escaping from aimed ground area and solidify the whole area of aimed ground uniformly, by pouring a specified grout into watery ground. CONSTITUTION:A water glass solution type grout (A) prepared by blowing CO2 gas into an aqueous solution of water glass and adjusting gelling time to from 1min to a few hours, a water glass solution type grout (B) prepared by blowing CO2 gas into (A) or a water glass suspension type grout (C) prepared by mixing a flow of a suspension of cement, lime, etc. with (A) is poured into soft or watery ground for solidification.

Description

[Detailed Description of the Invention] The present invention relates to a chemical injection method for injecting a water glass-based solidifying chemical into soft or leaky ground, and in particular uses carbon dioxide gas as the main reactant as a solidifying agent for the water glass solution. Related to chemical injection method.

Reactants conventionally used as solidifying materials for water glass solutions include inorganic and organic types. The former has the advantage that it is generally inexpensive and can solidify water glass in a relatively small amount, but on the other hand, the solidification is insufficient, there is a lot of syneresis water, and therefore the solid body itself shrinks rapidly and has low strength. It has its drawbacks. Although the latter has a good consolidation rate and generally excellent strength, it has the disadvantage that it requires a large amount for consolidation and is economically expensive. Therefore, in the latter case, an inorganic reactant is usually used in combination, but the more the amount of the inorganic reactant is increased, the more the unique advantages of the organic reactant are diminished. Furthermore, conventionally, both inorganic and organic reactants usually solidify water glass in the alkaline region.

It is a well-known fact that the solidification of water glass generally follows the process shown in Figure 1, and it is relatively easy to adjust the gelation time in a state close to instantaneous solidification, but it is difficult to adjust the gelation time in an alkaline region for a long time. It is very difficult to maintain the gelation time because the gelation time changes significantly due to a slight pH change, that is, a slight measurement error of the reactant.

Therefore, at present, inorganic reactants in particular are used exclusively for consolidating water glass in an instant solid state.

Conventional sulfuric acid, sodium hydrogen sulfate, etc. used in the neutralization reaction of water glass are strong acidic reactants, whereas carbonic acid is a very weak acidic reactant, and the water glass solution is mixed with these acidic reactants. In the case of neutralization, the relationship between the amount of acidic reactant added and pH generally follows the course shown in FIG.

The reaction between water glass and a strong acidic reactant is a so-called neutralization reaction between a strong acid and a strong alkali, and the pH rapidly decreases from a certain pH point until it reaches a relatively low pH of 4.

On the other hand, since carbonic acid is an extremely weak acid, the pH drop due to the neutralization reaction between water glass and carbon dioxide gas is extremely slow compared to the case of strong acidic reactants; It turns out that the adjustment is easy to crab inside the egg. Moreover, the pH is 6 due to excess carbon dioxide gas.
It has the characteristic that the pressure in the vicinity continues to be maintained at normal pressure and does not drop below that level.

By skillfully utilizing these properties of the reaction between water glass and carbon dioxide gas, carbon dioxide gas is first blown into the water glass aqueous solution to maintain a relatively long gelation time. Based on the permeable grout (hereinafter simply referred to as "permeable grout"), the permeable grout is further mixed with carbon dioxide gas and various reactants to maintain an instant setting state (hereinafter simply referred to as "permeable grout"). (hereinafter simply referred to as "suspension grout"), or suspension type grout (hereinafter simply referred to as "suspension grout"), which is a mixture of the permeable grout and a suspension of cement, lime, etc. It is characterized by injecting grout into the ground.

The present invention will be specifically described below with reference to Examples.

When carbon dioxide gas is blown into water glass aqueous solutions of various concentrations, the pH gradually decreases and the gelation time (when the specified pH is reached after blowing carbon dioxide gas, stop blowing carbon dioxide gas and stop). The time from the point of time to gelation) is shortened. An example of this progress is shown in Table 1.

Table 1 From Table 1, when carbon dioxide gas is blown into a water glass aqueous solution, if the concentration of water glass (expressed as the content of silicon dioxide in the water glass aqueous solution in Table 1) is dilute, the pH can be adjusted. Gelation will not occur unless carbon dioxide gas is blown until the gelatinization decreases. As the water glass concentration increases, gelation occurs with a slight decrease in pH. However, in any case, within the pH range that depends on the concentration of water glass, the gelation time is from several hours to several minutes, and it is relatively easy to adjust the pH value to maintain such a gelation time. It is. or,
It was found that it continued to maintain a low viscosity of several CPS or less until just before gelation, indicating that it had excellent properties as a permeable cloud.

If the gelation time is longer than several hours, or the gel is unconsolidated in the ground! , it is not appropriate as there is a risk of deviation.

Naturally, by further mixing carbon dioxide gas or other reactants or suspensions with these permeable grouts, it is possible to further shorten the gelation time and produce a flash-setting gel with a gelation time of 1 minute to 30 seconds or less. It's easy. In Table 1, the permeable grout is defined as liquid A, carbon dioxide gas or other reactive agent, and the suspension is liquid B, and the physical properties of the instant-setting grout obtained by combining liquids A and B are as follows. The measured results are shown in Table-2. The consolidation rate here refers to the percentage of the consolidated volume to the total volume.

Ship: Add 5 tablespoons of water to 50 ml of liquid A and blow carbon dioxide into it to set it instantly.

Rice 2: Solution B is a solution in which a specified amount of sodium hydrogen sulfate and sodium hydrogen carbonate are dissolved in 50 m of water.

Rice 3: Water 501nI! A suspension obtained by adding predetermined amounts of Portland cement and slaked lime to , is called liquid B.

The following is clearly seen from Table-2. Implementation number 2J~
Although the concentration of water glass in liquid A is the same in all cases of No. 34, in the case of execution numbers 25 to 34 that used carbon dioxide gas, compared to those of execution numbers 21 to 24 that did not use carbon dioxide gas at all. Both the consolidation rate and the -axial compressive strength are much better.

Even in implementation numbers 35 to 48, in which the water glass concentration was increased, in the case of implementation numbers 39 to 48, in which carbon dioxide gas was used, the consolidation rate, -axis, was higher than in the case of implementation numbers 35 to 38, in which carbon dioxide gas was not used at all. It can be seen that both the compressive strength and the compressive strength are extremely good.

When using carbon dioxide gas, sodium hydrogen sulfate, or thorium hydrogen carbonate as liquid B, carbon dioxide gas is used in a solution type grout in which the gelation time of the combined liquid of liquid A and B is adjusted to several seconds. Implementation number 25-27.30-32.3
9-41. Carbon dioxide gas is not used in 44-46. Is it the same water moth compared to implementation number 21.22.35.36? Regardless of its concentration, it is far superior as a flash setting solution type grout.

Also, implementation number 28.29.33 uses carbon dioxide gas even when cement and slaked lime are used as liquid B.
．． 34.42.43.47.48 is even better as a suspension type grout than implementation number 23.24.37.38, which does not use carbon dioxide, despite having the same water glass concentration. I understand.

As described above, the so-called permeable grout is basically a so-called permeable grout in which carbon dioxide gas is blown into a water glass solution to adjust the gelation time from about 1 minute to several hours, and in addition to this, carbon dioxide gas or other acidic reactants are added. They can be combined to form a solution-type instant setting grout, or a suspension of cement, slaked lime, etc. can be combined to form a suspension-type grout. The above-mentioned permeable grout, instantaneous grout, and suspension type grout can be injected into the ground individually to achieve their effect, but if the soil is soft and is formed by a complex interposition of coarse-grained soil and fine-grained soil, For reinforcement, injection pipes consisting of multiple pipes are inserted into the ground.
A permeable grout whose gelation time is adjusted from about 1 minute to several hours by blowing carbon dioxide gas into the water glass aqueous solution in 1 shot or 1.5 shots is always continuously fed, and carbon dioxide gas is poured into the gap from other pipes. Alternatively, an aqueous solution of other reactants or a suspension of cement, slaked lime, etc. is sent to join the permeable grout at the tip of the injection pipe, and then injected into the ground. The combined liquid is a so-called instant setting grout or suspension type grout.

In this way, using the instant setting grout or suspension grout and the permeable grout, first inject the instant setting grout or suspension grout into the ground while moving the injection step 7 by moving the injection pipe. As a result of moving the gap between the injection pipe and the ground and the stage, a solid seal with a packer effect is formed in the gap around the injection pipe, which allows the permeable grout to move along the gap around the injection pipe. In addition to preventing leakage in advance, instant setting grout or suspension grout is injected into rough or weak areas near the stage or at the interface between layers to prevent permeable grout from deviating outside the specified range. After pre-treatment, the seal is broken and the permeable grout is injected in an overlapping manner into the area where the flash setting grout or suspension grout has been injected, so that the flash setting grout or suspension grout cannot penetrate. The permeable grout penetrates between the particles in the thin parts and solidifies.

At this time, both the instant-setting grout or suspension type grout and the permeable grout according to the present invention using carbon dioxide gas have a higher solidification rate and -axial Since it has excellent compressive strength, it can sufficiently prevent the grout from deviating outside the range of the ground to be poured, and the ground to be poured can be made stronger and evenly consolidated over the entire area.

As water glass, it is of course applicable to No. 5181 to No. 3 as well as those with larger molar ratios, and as reactants for liquid B, carbon dioxide gas and hydrogen sulfate are used.l) Rum,
Add sodium bicarbonate to one side, but other inorganic reactants as well as general organic reactants such as aldehydes, esters, and organic acids can also be used6.As a suspension, use Portland cement. Although slaked lime and slaked lime are given as an example, various cements, bentonite gypsum, calcium carbonate, makneum carbonate, etc. can also be used.

Of course, inorganic or organic reactants and carbon dioxide gas can also be used in combination with the suspension.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between gelation time and pH of water glass. FIG. 2 is a graph showing the tendency of the pH to change with respect to the amount of the acidic reactant added in the neutralization reaction between water glass and the acidic reactant. Patent applicant: Reinforced Soil Engineering Co., Ltd. M

Claims (1)

[Claims] 1. In a ground injection method of injecting a solidification chemical into soft or leaky ground to solidify the ground, the solidification chemical may be any of the following (1), (2), or (3): ) A chemical injection method characterized by injecting a chemical solution into the ground. (1) A water glass solution type grout prepared by blowing carbon dioxide gas into a water glass solution so that the gelation time is 1 minute to several hours. (2) A water glass solution type grout prepared by further blowing carbon dioxide gas into the water glass solution type grout of (1) above or by combining a reactant solution so as to bring about an instantaneous setting state. (3) A water glass suspension grout made by combining the water glass solution grout of (1) with a suspension of cement, lime, etc. 2. In the construction method according to claim 1, the method (
Water glass solution type grout of 1) and the above (2) or (3)
A chemical injection method characterized by injecting water into the ground in combination with water glass grout.