JP5063896B2 - Liquid admixture for ground stabilization, ground stabilization material, and ground stabilization method using the same - Google Patents

Description

  The present invention relates to a liquid admixture for ground stabilization, a ground stabilization material, and a ground stabilization method using the same.

  As a ground stabilization method that improves and stabilizes soft ground such as soft ground, for example, cement milk is sprayed deeply into the ground at high pressure and mixed with soil to harden and stabilize. A construction method is mentioned (refer nonpatent literature 1).

  This method inserts a pipe that injects cement milk into the ground, and rotates the pipe to inject high pressure cement milk from the vicinity of the tip of the pipe to cut the soil in the ground. At the same time, the cut soil and cement milk In this construction method, the mixed soil mixed with is discharged to the ground through another pipe, the pipe is raised at a constant speed, and the ground is replaced with a mixture of cement milk and soil to harden and stabilize the ground. is there.

  In this method, when cement milk and soil are mixed, the cement particles and soil particles agglomerate with each other due to electrical action, so the viscosity of the mixed soil, which is a mixture of cement milk and soil, increases. There was a problem that it was difficult to discharge it to the ground.

  In order to reduce the viscosity of the mixed soil, as a liquid material, a naphthalene sulfonate formalin condensate, a melamine sulfonate formalin condensate, and / or an ultrahigh pressure jet injection method containing a polycarboxylic acid compound, etc. Cement additives are known (see Patent Document 1).

  In order to reduce the viscosity of the mixed soil, as a powder, a combination of substances containing phosphate and alkali metal (see Patent Document 3), a combination of phosphoric acid and inorganic powder (See Patent Document 7).

A combination of phosphates, alkali metal-containing substances (sulfates, sulfites, carbonates, bicarbonates, etc.), organic acids, ammonium salts and the like is known (Patent Document 1, Patent) (Refer to Literature 2, Patent Literature 4, Patent Literature 5, and Patent Literature 6).
Tsuboi, Naomichi, Practical chemical injection method, pages 5-9, March 25, 1981, Kashima Publishing Co., Ltd., 2nd edition issued Japanese Patent Laid-Open No. 06-127993 JP 05-254903 A Japanese Patent Laid-Open No. 06-206747 Japanese Patent Application Laid-Open No. 07-206495 Japanese Patent Application Laid-Open No. 07-069695 JP 2004-143041 A JP 09-194835 A

  In the ground stabilization method, the present invention enables quantitative pumping by liquefaction, and makes it possible to provide a high viscosity reduction effect and homogenize the injection compared to the case of using powder. A liquid admixture for use is provided.

The present invention is a liquid admixture for ground stabilization, comprising 100 parts of sodium dihydrogen phosphate and 20 to 300 parts of alkali metal chloride which is sodium chloride and / or potassium chloride, and sodium dihydrogen phosphate It is a liquid admixture for ground stabilization comprising 0.1 to 100 parts of organic acid which is sodium citrate and / or succinic acid with respect to 100 parts , and in 100 parts of liquid admixture for ground stabilization The ground stabilization liquid admixture having a solid content of 10 to 50 parts , the alkali metal chloride is sodium chloride, and the organic acid is sodium citrate. A ground stabilization material comprising 100 parts of cement, 1 to 50 parts of the liquid stabilizer for ground stabilization, and 30 to 500 parts of water, and the ground stabilization material having a pH of 0.5 to 6; Mixed with water And will have a slime viscosity of 100～15000MPas, after preparing the該地Release stabilizing liquid admixture is ground stabilization method comprising mixing cement.

  By using the ground stabilization liquid admixture and the ground stabilization material of the present invention, quantitative pumping is possible by liquefaction, and it is possible to impart a high viscosity reduction effect and make the injected material uniform. Play.

Hereinafter, the present invention will be described in detail.
Parts and% used in the present invention are based on mass unless otherwise specified.

  In the liquid admixture for ground stabilization of the present invention, phosphate is used. Phosphate has the effect of reducing the viscosity of the mixed soil.

  As phosphate, in addition to phosphoric acid, dihydrogen phosphate, dihydrogen pyrophosphate di-salt, metaphosphate, and hexametaphosphate have high solubility in water, and the solution is acidic. Such a substance is preferable, and these sodium salts, potassium salts, lithium salts, and the like can be used, and one or more of these can be used. Of these, use of phosphoric acid or dihydrogen phosphate is preferable.

  In the present invention, alkali metal chloride is used as a substance that reduces the delayed action of phosphate without affecting the viscosity reduction effect and enhances the strength development.

  Examples of the alkali metal chloride include chlorides such as sodium, potassium and lithium. One or two or more of these can be used. Of these, sodium chloride is preferred in terms of strength development.

  The amount of alkali metal chloride used is preferably 20 to 300 parts, more preferably 30 to 200 parts, per 100 parts of phosphate. If it is less than 20 parts, high strength development may not be obtained, and if it exceeds 300 parts, the stability of the liquid stabilizer for ground stabilization may be impaired and the contents may precipitate.

  In order to improve the viscosity reduction effect and stability of the liquid stabilizer for ground stabilization, it is preferable to use an organic acid.

  The organic acid is for stabilizing metal ions in the liquid admixture for stabilizing the ground, and is not particularly limited as long as it is a substance that can be used for this purpose. For example, at least one carboxyl group is contained. The organic acid preferably has 1 to 3, more preferably 2 to 3, and the use of an organic acid having 1 to 3 hydroxyl groups and / or 1 to 3 amino groups is also possible.

  Specific examples of organic acids include (1) monocarboxylic acids such as formic acid, acetic acid, and propionic acid, and (2) oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid. Dicarboxylic acids such as fumaric acid and phthalic acid, (3) tricarboxylic acids such as trimellitic acid and tricarbaryl, (4) oxymonocarboxylic acids such as hydroxybutyric acid, lactic acid and salicylic acid, and oxydicarboxylic acids of malic acid (5) aminocarboxylic acids such as aspartic acid and glutamic acid, (6) aminopolycarboxylic acids such as ethylenediaminetetraacetic acid (EDTA) and trans-1,2-diaminocyclohexanetetraacetic acid (CyDTA), and (7) ethylenediaminetetra ( Methylenephosphonic acid) [EDTPO], ethylenediaminedi (methylenephosphone) ) [EDDPO], nitrilotris (methylenephosphonic acid) [NTPO], phosphonic acids such as 1-hydroxyethylidene-1,1′-diphosphonic acid [HEDPO], (8) diketones such as acetylacetone and hexafluoroacetylacetone A complex-forming agent is mentioned. In the present invention, one or more of these complex forming agents can be used. A complexing agent containing an alkali metal can also be used.

  The organic acid is preferably 100 parts or less and more preferably 60 parts or less with respect to 100 parts of the phosphate. If it exceeds 100 parts, strength development may be inhibited. If the amount of organic acid is small, the intended effect may not be obtained, so 0.1 part or more, preferably 0.3 part or more may be added.

  The liquid admixture for ground stabilization can be obtained by adding phosphate and alkali metal chloride to water. In this case, the total amount of solids of phosphate and alkali metal chloride in 100 parts of the ground stabilization liquid admixture is preferably 10 to 50 parts, more preferably 15 to 35 parts. preferable. If the amount is less than 10 parts, a large amount of the ground stabilization liquid admixture is required, and the construction efficiency may be reduced. If the amount exceeds 50 parts, the stability of the ground stabilization liquid admixture is impaired, and the ground Since the viscosity of the liquid admixture for stabilization may increase, it is not preferable.

  0.5-6 are preferable and, as for pH of the liquid admixture for ground stabilization, 1-5 are more preferable. Outside this range, the stability of the ground stabilization liquid admixture may be impaired and the contents may precipitate.

Alkali metal sulfate can be used in combination as a substance that reduces the delayed action of phosphate without increasing the viscosity reducing effect and enhances strength development.
Examples of the alkali metal sulfate include sulfate and alum, and sodium sulfate, potassium sulfate, sodium alum and potassium alum can be used, and one or more of these can be used. It is. Among these, use of a sulfate is preferable in terms of strength development.

  The amount of alkali metal sulfate used is preferably 20 to 300 parts, more preferably 30 to 200 parts, relative to 100 parts of phosphate. If it is less than 20 parts, high strength development may not be obtained, and if it exceeds 300 parts, the stability of the liquid admixture for ground stabilization may be impaired, and the contents may precipitate.

  Phosphates, alkali metal chlorides and organic acids can be used either in powder form or dissolved. When using a powdery thing, it is preferable to mix with water and to dissolve by heating. Some of these may be present without being dissolved.

  In the case of dissolution, the temperature and time can be appropriately determined depending on the material, but the heating temperature is preferably 40 to 80 ° C. and the dissolution time is preferably 10 minutes to 3 hours. The temperature raising rate and the cooling rate are not particularly limited, and it is possible to dissolve using a material or warm water preheated to 40 to 80 ° C. in advance.

  It is preferable to stir at the time of dissolution, and it is possible to shorten the dissolution time by stirring. There are no particular limitations on the order of mixing the materials into the dissolution tank and the charging speed. In order to adjust the storage property in the dissolution tank and the time required for production, it is possible to adjust the pH using phosphoric acid, alkali metal hydroxide, carbonate, or the like.

The ground stabilization material has an excellent effect not only on clay soil but also on soil such as sandy soil and corrosive soil.
The mixing and stirring conditions of the present invention are not particularly limited as long as the ground stabilization liquid admixture, water and cement are mixed before high-pressure jetting into the ground, and these mixing methods include: Mixing and stirring can be performed by a batch mixing method in which mixing is performed by a grout mixer rotating at a rotational speed of about 10 to 1000 rpm, a continuous mixing method in which mixing is performed by a line mixer in which blades are installed in the tube, and the like.

  Cement is not particularly limited, and various portland cements such as normal, early strength, super early strength, and moderate heat, various mixed cements obtained by mixing blast furnace slag and fly ash with these portland cements, and commercially available It is also possible to use various Portland cements and various mixed cements by pulverizing them. Moreover, what was adjusted by increasing / decreasing the quantity of components (for example, gypsum etc.) normally used for cement can also be used.

  The amount of the ground stabilization liquid admixture is preferably 1 to 50 parts, more preferably 3 to 30 parts, relative to 100 parts of cement. If it is less than 1 part, the effect of viscosity reduction may be small, and if it exceeds 50 parts, strength development may be inhibited.

  The amount of water used for producing the ground stabilization material is usually preferably 30 to 500 parts, more preferably 50 to 300 parts, relative to 100 parts of cement. If it is less than 30 parts, the fluidity of the slime, which is a mixture of cement milk and soil, is small, and if it exceeds 500 parts, the strength development may be hindered. It can be adjusted as appropriate depending on the moisture content of the soil.

  It is possible to use water reducing agents, especially high performance water reducing agents, for soil conditions and construction reasons.

  A water reducing agent means what is used in order to improve the fluidity | liquidity of cement concrete, and both liquid form and powder form can be used. The water reducing agent is not particularly limited. For example, lignin sulfonic acid type, naphthalene sulfonic acid type, polycarboxylic acid type and the like can be used.

  The ground stabilization method is, for example, as follows. Drill holes where ground improvement is required. The diameter of the drilling hole is not particularly limited as long as the injection rod can be inserted. The depth of the drilling hole is changed depending on the region to be improved, and is not particularly limited, but is usually about 10 to 50 m.

A double tube or triple tube injection rod is inserted, and cement milk is pumped using a grout pump, an ultrahigh pressure pump, or a compressor, and injected from a double tube or triple tube nozzle. The pressure of cement milk is preferably as high as possible, but is usually about 50 to 700 kg / cm ² in consideration of wear of the double pipe, triple pipe, or nozzles thereof. The amount of cement milk fed is not particularly limited, but is preferably about 30 to 800 liters / minute.

  The cement milk thus injected at high pressure in the ground is mixed and stirred together with the soil, and the injection rod ascends to the ground at a constant speed while rotating, so it finally consists of cement milk and soil. A columnar pile is formed in the ground.

  The viscosity of the slime is preferably from 100 to 15000 mPas, more preferably from 500 to 10,000 mPas. If it is less than 100 mPas, the material separation may not form a homogeneous pile, and if it exceeds 15000 mPas, the fluidity of the slime is poor, the excess slime cannot be discharged to the ground, and the homogeneous pile is not formed. Problems may arise.

The diameter of the pile varies depending on soil conditions such as N value indicating the hardness of the ground and construction conditions such as injection pressure, and is not particularly limited, but 0.5 to 20 m is appropriate. The length of the pile can be about 3 m to 50 m.
Hereinafter, the present invention will be described in detail based on examples.

The phosphate and alkali metal chloride shown in Table 1 were mixed with water so as to have a solid content shown in Table 1, and stirred at 50 ° C. for 30 minutes to prepare a liquid admixture.
Next, 10 parts of the prepared liquid admixture was mixed with 100 parts of cement, and 140 parts of water was further mixed to prepare cement milk.
This cement milk was mixed with clay having a water / powder mass ratio of 120% at a volume ratio of 1: 1 to obtain a slime, and its viscosity and compressive strength were measured. The results are also shown in Table 1.

<Materials used>
Cement: Ordinary Portland cement, commercial product, density 3.15 g / cm ³
Phosphate a: Sodium dihydrogen phosphate, Commercially available phosphate b: Phosphoric acid, Commercially available alkali metal chloride A: Sodium chloride, Commercially available alkali metal chloride A: Potassium chloride, Commercially available clay: Bentonite powder, Commercial product, density 2.30 g / cm ³

<Measurement method>
Viscosity: Measure the obtained slime with a B-type viscometer under the conditions of temperature 20 ° C., humidity 80%, rotation speed 20 rpm. Compressive strength: Pour the obtained slime into a 4 cm × 4 cm × 16 cm mold and remove it after curing. The specimen obtained by molding was sealed at a temperature of 20 ° C., and the compressive strength at age 7 days was measured.

  From Table 1, it is understood that a high strength value can be obtained by using 20 to 300 parts of alkali metal chloride with respect to 100 parts of phosphate. Moreover, it is important that the admixture is in solution, and it can be seen that No1-10 using the respective components in powder form cannot obtain an excellent viscosity reducing effect.

  The same procedure as in Example 1 was conducted except that the phosphate, alkali metal chloride, and organic acid shown in Table 2 were mixed and stirred at 50 ° C. for 30 minutes to prepare a liquid admixture. The results are also shown in Table 2.

<Materials used>
Organic acid A: Sodium citrate, commercial product Organic acid B: Succinic acid, commercial product

  From Table 2, it can be seen that a further excellent viscosity reducing effect can be obtained by using 0.1 to 100 parts of organic acid with respect to 100 parts of phosphate.

100 parts of phosphate a and 100 parts of alkali metal chloride were mixed and stirred at 50 ° C. for 30 minutes to prepare a liquid admixture having a solid content of 20%.
To 100 parts of cement, the prepared liquid admixture in the amount shown in Table 3 was mixed with water to prepare 150 parts of a solution, which was mixed with cement to prepare cement milk.
The cement milk was mixed with clay having a water / powder mass ratio of 120% in a ratio of 1: 1 by volume with the cement milk to obtain a slime. The viscosity and compressive strength of this slime were measured. The results are shown in Table 3.

From Table 3, it is understood that an excellent viscosity reducing effect can be obtained by using 1 to 50 parts of the liquid stabilizer for ground stabilization with respect to 100 parts of cement. However, since the strength value is low at 50 parts, a more preferable use range is 3 to 30 parts.

Claims (7)

A liquid admixture for stabilizing a ground comprising 100 parts of sodium dihydrogen phosphate and 20 to 300 parts of alkali metal chloride which is sodium chloride and / or potassium chloride. The liquid admixture for ground stabilization according to claim 1 , comprising 0.1 to 100 parts of an organic acid which is sodium citrate and / or succinic acid with respect to 100 parts of sodium dihydrogen phosphate . For ground stabilized liquid admixture in 100 parts of soil stabilizing liquid admixture of claim 1 or claim 2 solids is 10 to 50 parts. The liquid admixture for ground stabilization according to claim 2, wherein the alkali metal chloride is sodium chloride and the organic acid is sodium citrate. A ground stabilization material comprising 100 parts of cement, 1 to 50 parts of a liquid stabilizer for ground stabilization according to any one of claims 1 to 4 , and 30 to 500 parts of water. A slime having a viscosity of 100 to 15000 mPas, which is obtained by mixing the ground stabilizing material according to claim 5 and water having a pH of 0.5 to 6. The ground stabilization method formed by mixing the cement after preparing the liquid admixture for ground stabilization as described in any one of Claims 1-6.