JP2000313880A - Natural ground improver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a natural ground improver of good workability utilizing a polymer elastic gel. SOLUTION: This improver comprises a main liquid contg. a water soluble polysaccharide capable of gelation by a curing agent, and a second liquid contg. either one of curing agents listed below. It is pref. that the medium of the main liquid is a lower alcohol, or the like. (1) an alkali metal ion or an alkaline earth metal ion, (2) boric acid or another boron compd, (3) an acid or an alkali, (4) a specific water soluble polysaccharide which forms a gel by reaction with a curing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a main solution using a water-soluble polysaccharide of the type that gels by the action of a curing agent, and a second liquid having the action of gelling the water-soluble polysaccharide by a certain mechanism. The present invention relates to a two-part curing type mountain improver comprising a liquid.

[0002]

2. Description of the Related Art In construction work such as tunnel excavation, a ground improvement agent is injected into ground (ground) for the purpose of improving ground, stopping water such as spring water, backfilling a shield method, and the like. That is what is being said. Conventionally, various types of such ground improvers have been used, and for example, a type in which water glass is cured is typical.

[0003] Incidentally, water glass and the like become very hard after hardening, which is not always advantageous for the purpose of, for example, absorbing vibration or displacement of the ground, and is included in sediment discarded as "slipping". In view of the fact that the obtained curing agent is not easily decomposed in a natural environment, a curing agent that gels the polysaccharide has been studied.

[0004] For example, in the invention of "Soil improvement material and application of the same" disclosed in Japanese Patent Application Laid-Open No. 4-169613, fibers are added to an aqueous solution of a hydrophilic material such as agar or gelatin which melts and solidifies due to a temperature change. Disclosed is a ground improvement material obtained by mixing.

[0005]

However, the ground improvement material disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 4-169613 has excellent vibration / displacement absorption as a so-called polymer elastic gel, and has a high degree of decomposition when discarded. Even if it can be expected, extra equipment is required due to the necessity of a heating device and a heat retaining device for sol → gel transition at the site of use, and good timing immediately before filling the ground There was a problem that the sol-to-gel transition work was required to be performed while the temperature was maintained, which caused inconvenience to the work.

Accordingly, an object of the present invention is to provide a ground improver utilizing a polymer elastic gel, which does not have the above-mentioned problems.

[0007]

Means for Solving the Problems (Structure of the First Invention) The structure of the first invention (the invention of claim 1) for solving the above-mentioned problems is that the main liquid to be mixed at the time of use and the first liquid are used. A two-part curing type soil improver comprising two liquids, wherein the main liquid contains a water-soluble polysaccharide which gels by the action of a curing agent, and the second liquid contains the water-soluble polysaccharide. It is a soil improver containing a curing agent that gels polysaccharides.

(Structure of the Second Invention) The structure of the second invention of the present application (the invention described in claim 2) for solving the above problems is as follows.
The water-soluble polysaccharide according to the first invention is carrageenan, alginic acid, alginate, gellan gum, glucono delta lactone, azotobacter vineland digum, xanthan gum, pectin, guar gum, locust bean gum,
At least one selected from tara gum, cassia gum, glucomannan, tragacanth gum, karaya gum, pullulan, gum arabic, arabinogalactan, dextran, carboxymethylcellulose sodium salt, methylcellulose, silium sheet gum, starch, chitin, chitosan and curdlan. It is a mountain improver.

(Structure of Third Invention) The structure of the third invention (the invention described in claim 3) for solving the above-mentioned problem is as follows.
The hardener according to the first invention or the second invention is a soil improver which is one of the following 1) to 4) in combination with a predetermined one of the water-soluble polysaccharides. 1) alkali metal ion or alkaline earth metal ion 2) boric acid or other boron compound 3) acid or alkali 4) predetermined water-soluble polysaccharide which reacts with the water-soluble polysaccharide to form a gel (the constitution of the fourth invention) 4) The present application for solving the above-mentioned problem.
The structure of the invention (the invention according to claim 4) is such that the main liquid according to the first to third inventions has a composition in which the water-soluble polysaccharide is hardly dissolved, and the second liquid is a solution in which the water-soluble polysaccharide is dissolved. It is a ground improver having a composition that is easy to be used.

(Structure of Fifth Invention) The structure of the fifth invention (the invention described in claim 5) for solving the above problems is as follows.
The main liquid according to the fourth aspect of the present invention has a composition in which a high concentration aqueous solution of a lower alcohol or a polyhydric alcohol or a non-dissociable low molecular organic substance is used as a medium, and the second liquid has a composition in which water is used as a medium. It is an improver.

(Structure of the Sixth Invention) The structure of the sixth invention (the invention according to claim 6) for solving the above problems is as follows.
A two-part curing type soil improver comprising a main liquid to be mixed at the time of use and a second liquid, wherein the main liquid comprises a water-soluble polysaccharide which gels by the action of a curing agent, The soil improvement agent contains the curing agent maintained in an inactive state in operation, and the second liquid contains a trigger agent for converting the inactive curing agent into an active state.

[0012]

[Action / Effect of the Invention] (Action / Effect of the First Invention) The ground improver of the first invention cures a water-soluble polysaccharide by gelation, and is therefore a ground improver utilizing a polymer elastic gel. In addition to exhibiting excellent vibration absorption and displacement absorption, it can be expected to decompose in a natural environment, for example, when it is discarded by being included in “slipping”.

Further, since the curing can be performed only by mixing the main liquid and the second liquid at room temperature, a heating device or a heat retaining device is not required, and a special operation is performed immediately before filling the ground. It is not necessary to use a normal two-liquid mixing and filling machine, so that workability on site is good.

(Function / Effect of the Second Invention) The water-soluble polysaccharides listed in the second invention are typical examples of those which gel (cure) by mixing with a certain curing agent at ordinary temperature, By using two or more kinds, the action and effect of the first invention are particularly preferably exhibited.

(Function / Effect of the Third Invention) In combination with a predetermined water-soluble polysaccharide, 1) of the third invention
By using any one of the curing agents (1) to (4), the operation and effect of the first invention are particularly preferably exhibited.

(Function / Effect of the Fourth Invention) Since the main liquid has a composition in which the water-soluble polysaccharide is hardly dissolved, the water-soluble polysaccharide in the main liquid is kept in a non-dissolved state (for example, a suspension state). As a result, the low viscosity of the main liquid is maintained, and the handling of the main liquid up to that time, including the mixing operation in the mixing and filling machine, is significantly facilitated.

Furthermore, the water-soluble polysaccharide starts to be dissolved by being mixed with the second liquid having a composition that is easily dissolved, and then starts a curing reaction with a curing agent. Due to its characteristic that it does not dissolve immediately,
Even when mixed with the second liquid, the curing reaction is delayed. For this reason, the excellent behavior of the water-soluble polysaccharide, which can easily and sufficiently penetrate into the ground in an uncured (low-viscosity) state while being cured after that, can be secured.

(Function / Effect of Fifth Invention) As an excellent embodiment of the fourth invention, a high concentration aqueous solution of a lower alcohol, a polyhydric alcohol, or a low molecular weight non-dissociable substance is used as in the fifth invention. And the second liquid has a composition using water as a medium.

In these cases, since the free water necessary for dissolving the water-soluble polysaccharide does not exist at all or almost in the main solution, the water-soluble polysaccharide in the main solution is not dissolved in a suspension or the like. Only after being kept and mixed with the second liquid containing water as a medium, sufficient free water is obtained and begins to dissolve, reacting with the curing agent with the above-mentioned reaction delay, and gelling.

(Function / Effect of the Sixth Invention) In the sixth invention, by mixing the main liquid and the second liquid, the curing agent in the main liquid changes to an active state in the curing action. The same action and curing can be obtained.

[0021]

Next, embodiments of the first invention to the sixth invention will be described. In the following, simply "the present invention"
When it says, it refers to 1st invention-6th invention collectively.

The soil improver of the present invention comprises a main solution containing a water-soluble polysaccharide which gels by the action of a hardener, and a hardener which gels the water-soluble polysaccharide. It is a two-part curing type composed of the contained second liquid, or contains a water-soluble polysaccharide that gels by the action of the curing agent and a curing agent that is maintained in an inactive state in the curing action. And a second liquid containing a trigger liquid for converting an inactive hardener into an active hardener.

Although the specific use of the soil improver is not limited, for example, in the excavation work of tunnels and other various civil engineering works, the solidification and reinforcement of the ground, and the provision of vibration absorption and displacement absorption to the ground. It can be injected and filled into the ground (ground) for the purpose of ground improvement, water stopping such as spring water, backfilling of shield method, etc.

The specific method of using the soil improver is not limited. For example, as a so-called chemical liquid injection method, an injection hole is drilled in the ground with a rock drill such as a drifter or a leg hammer mounted on a crawler jumbo or the like. The main liquid and the curing liquid can be injected and filled into the injection hole while mixing the main liquid and the curing liquid by using a mixing and filling machine called a mixer or the like.

[Main Solutions of First to Fifth Inventions] First Invention to
In the fifth invention, the main liquid contains at least one or more water-soluble polysaccharides of the type that gel by the action of a curing agent. The water-soluble polysaccharide of the type that melts and solidifies due to a temperature change is not usually included in the water-soluble polysaccharide of the present invention, but when it has a property of gelling by the action of a predetermined curing agent, It can be used as the water-soluble polysaccharide of the present invention.

The water-soluble polysaccharides according to the present invention include carrageenan, alginic acid, alginates, gellan gum, glucono delta lactone, azotobacter vinelandi gum,
Xanthan gum, pectin, guar gum, locust bean gum, tara gum, cassia gum, glucomannan, tragacanth gum, karaya gum, pullulan, gum arabic,
Representative examples include arabinogalactan, dextran, carboxymethylcellulose sodium salt, methylcellulose, sylum sheet gum, starch, chitin, chitosan and curdlan.

The medium (solvent or dispersion medium) of the main liquid may be water, but a more preferable medium has a composition in which the water-soluble polysaccharide is hardly dissolved, especially a lower alcohol or polyhydric alcohol, or A high concentration aqueous solution of a non-dissociable low molecular weight organic substance (for example, 70%
% By weight or more), and particularly preferably a lower alcohol. Lower alcohols include methanol,
Preferable examples include ethanol, isopropanol, propylene glycol, and glycerin.

When the medium of the main liquid has a composition in which the water-soluble polysaccharide is hardly dissolved as described above, the main liquid is maintained at a low viscosity until immediately before use, as described above, so that its handling is convenient. In addition, the gel can be formed after the water-soluble polysaccharide is easily and sufficiently filled and permeated into the ground.

The concentration of the water-soluble polysaccharide in the main solution is not particularly limited as long as the concentration is not so low that the gel-forming ability is insufficient, or is not so high that the viscosity becomes inconvenient to handle. Since the upper and lower limits of these concentrations vary depending on the type of the water-soluble polysaccharide and the purpose of use of the soil improver, they cannot be uniformly defined.

When the medium of the main liquid has a composition in which the water-soluble polysaccharide is difficult to dissolve, the water-soluble polysaccharide can be maintained in a low viscosity state such as a powder dispersion. It can be contained in a high concentration of about 45% by weight.

[Second liquid of the first to fifth inventions] In the first to fifth inventions, the second liquid contains at least a curing agent for gelling the water-soluble polysaccharide of the main liquid. I have. Any of the following 1) to 4) can be optionally used as a curing agent in combination with the water-soluble polysaccharide described above. When the main liquid is an aqueous solution of a water-soluble polysaccharide, the medium of the second liquid may be at least a composition that does not inhibit the dissolution of the water-soluble polysaccharide. If the composition has a difficult composition, water is used.

1) Alkali metal ions such as potassium or alkaline earth metal ions such as calcium and magnesium. Specifically, for example, chlorides of these ions and other suitable salts can be added to the second liquid.
In this case, carrageenan, alginate, gellan gum, Azotobacter vinelandi gum, pectin, sodium carboxymethylcellulose, etc. can be used as the water-soluble polysaccharide of the main solution.

2) Boric acid and other boron compounds. In this case, guar gum, locust bean gum, tara gum, cassia gum, or the like can be used as the water-soluble polysaccharide of the main solution.

3) Acid or alkali. Specifically, the pH of the main solution is adjusted to a pH sufficient to gel the water-soluble polysaccharide,
Acids or alkalis such as hydrochloric acid and ammonia solution can be added to the second solution. In this case, alginate, glucomannan, pectin, chitin, chitosan, curdlan, or the like can be used as the water-soluble polysaccharide of the main solution.

4) A predetermined water-soluble polysaccharide which reacts with the water-soluble polysaccharide to form a gel. Specifically, a combination of using xanthan gum as the main liquid and cassia gum as the second liquid (or vice versa), a combination of using carrageenan as the main liquid and using locust bean gum as the second liquid (or vice versa). And the like.

When the main liquid is an aqueous solution of a water-soluble polysaccharide, the medium of the curing liquid is not particularly limited as long as the composition does not inhibit the dissolution of the water-soluble polysaccharide. When the medium has a composition in which the water-soluble polysaccharide is hardly dissolved, it is preferable to use water as the medium.

[Embodiment of the Sixth Invention] In the sixth invention, the same water-soluble polysaccharide and curing agent as those in the first to fifth inventions can be basically used. However, in order to allow the water-soluble polysaccharide and the curing agent to coexist in the main liquid, the curing agent must be of a type that can be changed between an inactive state and an active state in the curing action by a certain means. In addition, it is necessary to include a trigger agent for converting an inactive curing agent into an active state in the second liquid.

As a specific example, when an alkali metal ion is used as a curing agent for a water-soluble polysaccharide, the pH of the main solution is adjusted to neutral to alkaline, and an alkali metal salt that dissociates ions only in an acidic region. Is contained in the main liquid, and the second liquid has a composition capable of making the pH of the main liquid acidic.

[Embodiment of the ground improvement agent] The following (a)
(G) illustrates some particularly preferred specific embodiments of the soil improver according to the present invention.

(A) The main solution is a dispersion of guar gum powder, which is a water-soluble polysaccharide obtained from endosperm of guar plant legume seeds, in a lower alcohol or a polyhydric alcohol. An aqueous solution of another boron compound (borate ion solution).

As a more detailed embodiment, 150 g of powdery guar gum and 230 g of propylene glycol are mixed and dispersed in the main liquid (the guar gum does not dissolve, and the main liquid is a low-viscosity dispersion liquid). In the above, 2 g of borax is dissolved in 1 kg of water. By mixing the main liquid and the curing liquid, guar gum was swelled and dissolved by free water supplied from the curing liquid, and then reacted with borax ions to form a uniform gel.

At this time, by adjusting the particle size of the powdery guar gum, it was possible to arbitrarily control the dissolution rate of the guar gum and, consequently, the gelation rate after mixing the main liquid and the curing liquid. That is, the particle size of guar gum is 100 μm
When the guar gum has a particle size of 180 μm, the dissolution rate is 20 minutes.
The guar gum dissolution rate could be controlled in the range of 1 minute to 20 minutes by choosing a particle size within that range.

(B) Carrageenan, which is a partially sulfated straight-chain galactan obtained from a plant of the red alga Cypressiaceae, particularly a carrageenan having a high gel-reactive κ structure, is used as a main liquid. It is an aqueous solution (or a lower alcohol dispersion having a higher concentration) in the range of 2 to 5% by weight, and the curing liquid is a cation liquid such as calcium chloride, magnesium chloride or ammonium chloride.

(C) The main solution is an aqueous solution (or a lower alcohol dispersion) of sodium alginate obtained by alkali-neutralizing the free alginic acid extracted from brown algae and acidified and precipitated, and the hardening solution is calcium chloride, chloride It is a cation liquid such as magnesium and ammonium chloride.

(D) The main solution is a microorganism Pseudomonas elode
a) is preferably used as an aqueous solution having a concentration of 0.2% by weight or less, which can be maintained in a liquid state at ordinary temperature, or a citric acid having a higher concentration based on a novel finding of the present inventors. An aqueous solution that has been rendered water-soluble at room temperature by the combined use of a sequestering agent such as sodium is used, and the curing liquid is an alkali metal ion liquid or an alkaline earth metal ion liquid.

(E) An aqueous solution of pectin, which is a water-soluble polysaccharide extracted from pectin contained in citrus peels such as lemon and lime and apple pomace (or
Lower alcohol dispersion), and the curing liquid is a divalent or higher cation liquid such as an alkaline earth metal ion.

(F) Sodium alginate 1 as main solution
0 g and 10 g of dicalcium phosphate are dissolved in 1 kg of water, and glucono delta lactone (GDL) 2 is used as a second liquid.
0 g is dispersed in 20 g of propylene glycol in a non-dissolved state.

In the main liquid, the dissolution of sodium alginate is suppressed due to calcium ions slightly dissolved in water, the low viscosity of the main liquid is maintained, and gelation due to the reaction of sodium alginate with calcium ions occurs. Absent.

When the main solution is mixed with the second solution, GDL as a trigger agent starts to be dissolved by the main solution, whereby the mixed solution shifts to the acidic side, elution of calcium ions starts, and this ion The sodium alginate gels by the reaction.

In this embodiment, the gelation reaction takes place because gelation occurs as a result of a several-step reaction series, and in particular, the dissolution rate of GDL dispersed in alcohol by contact with the main solution is slow. Speed control is easy.

(G) As the main liquid, microorganisms Xanthomonas c
10 g of xanthan gum produced by ampestris is dispersed in 20 g of propylene glycol, and as a second liquid, cassia gum 15 obtained from seed endosperm of leguminous Ebisugusamodoki is used.
g was heated and dissolved in 1 kg of water. By mixing the main liquid xanthan gum and the second liquid cassia gum, a gel having strong viscoelasticity was formed.

In the above-described embodiments (a) to (g), GDL and the like are not necessarily mixed and dispersed in a liquid phase, but may be used in a solid phase such as a powder to which a dispersant such as dextrin or lactose is added. It is also possible.

[0053]

EXAMPLES Main liquids (shown in the first row of Table 1) and second liquids (Table 1) having the compositions shown in Examples (Examples 1 to 4) and Comparative Examples (Examples 5 and 6) in Table 1 at the end. (Indicated in the second stage of No. 1) was prepared. The numerical values shown in Table 1 are in parts by weight.

For each of the above examples, the viscosity immediately after mixing the main liquid and the second liquid (after 30 seconds) was measured by a single cylinder rotational viscometer or a vibrating viscometer method. In Example 5, the viscosity was measured 30 seconds after mixing. Table 1 shows the results.

Next, these mixed solutions were mixed at a ratio of 1: 1 or 2: 1.
Is mixed with silica sand No. 7 at a mixing ratio of 3 and cast into a concrete formwork, and two cylinders each having a diameter of 50 mm x a length of 100 mm are formed for each example, and the displacement at the time of displacement of 10%, 20% and 30% Each compressive strength (MPa), elastic modulus (MPa), and maximum yield point were measured. Table 1 shows the measured values of the two cylindrical samples and their average values for each example.

As can be seen from the results shown in Table 1, in each of the examples, the viscosity immediately after mixing the main liquid and the second liquid was low, and the liquid was mixed with sand and solidified. . Furthermore, no maximum yield point was observed. In addition, as a result of using the chemical solution of Example 1 and injecting into the sand tanks of silica sand Nos. 4 to 7 using a pump, a good improved body was obtained with any of the silica sands.

[0057]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C08L 3/02 C08L 3/02 5/00 5/00 5/02 5/02 5/04 5/04 5 / 06 5/06 5/08 5/08 C09K 17/32 C09K 17/32 H E02D 3/12 101 E02D 3/12 101 // C09K 103: 00 (72) Inventor Shinya Uda Kodai, Komaki City, Aichi Prefecture 3600, Gezu Tokai Rubber Industry Co., Ltd. (72) Inventor Motohiro Katayama, Omaki, Komaki-shi, Aichi Prefecture, Japan 3600 Gezu, Tokai Rubber Industry Co., Ltd. Toyama Rubber Co., 3600 Tokai Rubber Industries Co., Ltd. (72) Inventor Yuji Ujihashi 5074 Nishiharuka, Ina-shi, Nagano Ina Food Industry Co., Ltd. Food industry stock F term in the company (reference) 2D040 AA04 AA06 AB01 BB09 CA10 CB03 4H026 CB02 CB08 CC06 4J002 AB031 AB041 AB051 DD066 DK006 EC037 EC057 GL00

Claims (6)

[Claims] Claims: 1. A two-part curing type mountain improver composed of a main liquid and a second liquid to be mixed at the time of use, wherein the main liquid has a water-soluble property which is gelled by the action of a curing agent. A soil improver comprising a polysaccharide, and the second liquid contains a curing agent for gelling the water-soluble polysaccharide. 2. The water-soluble polysaccharide comprises carrageenan, alginic acid, alginate, gellan gum, glucono delta lactone, azotobacter vineland digum, xanthan gum, pectin, guar gum, locust bean gum,
At least one selected from tara gum, cassia gum, glucomannan, tragacanth gum, karaya gum, pullulan, gum arabic, arabinogalactan, dextran, carboxymethylcellulose sodium salt, methylcellulose, silium sheet gum, starch, chitin, chitosan and curdlan. The soil improver according to claim 1, characterized in that: 3. The method according to claim 1, wherein the curing agent is one of the following 1) to 4) in combination with a predetermined one of the water-soluble polysaccharides.
The soil improvement agent according to any one of the above. 1) alkali metal ion or alkaline earth metal ion 2) boric acid or other boron compound 3) acid or alkali 4) predetermined water-soluble polysaccharide which reacts with the water-soluble polysaccharide to form a gel 4. The method according to claim 1, wherein the main liquid has a composition in which the water-soluble polysaccharide is hardly dissolved, and the second liquid has a composition in which the water-soluble polysaccharide is easily dissolved. Item 3
The soil improvement agent according to any one of the above. 5. The method according to claim 1, wherein the main liquid has a composition using a high-concentration aqueous solution of a lower alcohol, a polyhydric alcohol, or a non-dissociable low-molecular-weight organic substance as a medium, and the second liquid has a composition using water as a medium. The soil improver according to claim 4, characterized in that: 6. A two-part curing type mountain improver composed of a main liquid and a second liquid to be mixed at the time of use, wherein said main liquid is a water-soluble gel that is gelled by the action of a curing agent. A polysaccharide and the curing agent that is maintained in an inactive state in a curing action are included, and the second liquid includes a trigger agent that changes the inactive curing agent into an active state. And ground improver.