JPH0691999B2 - Treatment method for wet excavated soil - Google Patents

Description

TECHNICAL FIELD The present invention relates to a soil improvement method for eliminating the fluidity of water-containing excavated residual soil generated at a tunnel construction site or the like of an earth pressure system shield method.

The above-mentioned excavated soil has a fluidity so as to be easily discharged from the inside of the cutter chamber and the like, and has a property of maintaining water stopping property. The fluidity is controlled by a slump test and often has a slump value of 5 cm or more. Since it is difficult to transport it by a dump truck if it has liquidity, various liquidity disappearance methods have been conventionally studied.

[Prior Art] In order to remove the fluidity of the hydrated residual soil, natural leaching in the residual soil hopper and sun drying are performed.

As an example of adding a chemical, a cement type (Japanese Patent Publication No. 62-4200)
JP-A), lime type (Japanese Patent Publication No. 62-318), superabsorbent resin (JP-A-59-155488) and the like, and guar gum and the like are used. In addition, a bubble shield method has been proposed in which bubbles are mixed in order to maintain the fluidity while reducing the water content, and the fluidity is removed by defoaming (Japanese Patent Publication Sho).
58-47560, Japanese Patent Publication No. 59-4999).

[Problems of the prior art] When a cement-based or lime-based solidifying agent is used alone in a treatment method using a chemical, the property of the treated soil becomes unsuitable for vegetation due to a rise in pH and solidification over time. Alternatively, there are inconveniences such as hopper blockage problems due to solidification.

The use of super absorbent resin is expensive.

The use of guar gum limits the use of the treated soil because it deteriorates over time due to mold and spoilage. In addition, as it is a natural product, price fluctuations are large and there is concern about supply.

When a high-molecular-weight synthetic water-soluble polymer substance such as an acrylic polymer flocculant is added to a hydrous soil in a powder state and kneaded, it does not uniformly disperse and becomes a mamko shape, which causes a foreign substance feeling. And the effect of preventing fluidity cannot be exerted.

Further, when the polymer flocculant is added as a low-concentration aqueous solution which is a general use form in water treatment, the fluidity of the treated soil is increased by adding a large amount of water to the excavated soil.

[Means for Solving Problems] As a result of earnest studies to solve the above problems, the present inventor found that
The present invention has been reached.

According to the present invention, the water-containing excavation residual soil generated at the tunnel construction site is kneaded with an anionic acrylic polymer flocculant dispersion liquid in an amount of 0.1 to 5 kg as a polymer pure content per 1 m ³ of the hydrous excavation residual soil, followed by lime-based coagulation. 1 to 100 kg of the agent is added and kneaded.

The acrylic polymer flocculant dispersion liquid used here has a viscosity of 1
It is desirable that the concentration is 10,000 cp or less and the concentration is 10% or more.

If the viscosity is too high, the kneading becomes non-uniform, and if the concentration is too low, a large amount of liquid is added to the residual soil, which adversely affects flow prevention. The anionic acrylic polymer flocculant used in the present invention is an anionic polyacrylamide containing 10 to 50 mol% of carboxyl groups, which is a copolymer of acrylamide and acrylate, acrylamide and 2-acrylamide alkyl sulfonate, and Acrylic water-soluble polymer with a molecular weight of 1 million or more, preferably 2 million or more is applied from copolymers of acrylates, etc., and is dispersed in oil or salt aqueous solution as fine particles with a particle size of 100 μm or less. Used in.

A method for producing such a dispersion is known, and water-in-oil emulsions are described in JP-B-34-10644, JP-B-52-39417 and JP-B-55-45783, and a dispersion in a salt aqueous solution is disclosed. The manufacturing method is disclosed in Japanese Examined Patent Publication No. 46-14907 and Japanese Unexamined Patent Publication No.
It is described in JP-A-2-20511.

As the lime-based coagulant, a calcium compound selected from quick lime, slaked lime and / or cement is used. It is desirable to use these lime-based coagulants in a water-free state, that is, in the form of powder, granules, small lumps, etc., and 1 to 100 kg / m ³ is added to the hydrous excavated residual soil and kneaded. In order to knead the acrylic polymer coagulant dispersion liquid and the lime-based coagulant into the water-containing excavation residual soil, a kneader such as a continuous mixer or a forced agitation mixer is used, and also a civil engineering machine such as a power shovel or a screw conveyor is used. It is also possible.

[Operation] In the present invention, since the anionic acrylic polymer flocculant is added as a low-viscosity fine particle dispersion, it is easily mixed with the water-containing excavated residual soil and the surface of the soil particles is adsorbed and coated. It is considered that the lime-based coagulant added next imparts calcium ions to the anionic hydrophilic group in the soil particles and the carboxyl group in the polymer flocculant, and exhibits a hydrophobizing phenomenon. In addition, quicklime and cement have a dehydrating action, and it is possible that they exhibit a synergistic action.

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

(Synthesis Example-1) A commercially available polymer flocculant (copolymer of sodium acrylate and acrylamide; anionization rate: 20 mol%; molecular weight: 6 million) was pulverized with a pole mill and passed through a 200-mesh sieve to obtain fine powder (powder- The liquid in which 1) was dispersed in 9 times the amount of polyethylene glycol was used as sample-1, and the liquid in which the 20 to 40 mesh part (powder-2) from which the flocculant before pulverization was sieved was mixed with 9 times the amount of polyethylene glycol was used. It is referred to as Comparative Sample-1.

(Synthesis example-2) 1 equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introducing pipe
Medium oil in a 5-neck separable flask (specific gravity 0.83, flash point
138 ℃) 282g was charged, sorbitan monooleate 10g, IC
20 g of Hypermer B-246 manufactured by I and 0.3 g of lauroyl peroxide were added and dissolved at room temperature.

Separately, a monomer solution prepared by dissolving 262 g (90 mol%) of acrylamide and 38 g (10 mol%) of sodium acrylate in 328 g of ion-exchanged water was prepared, and then poured into the aforementioned separable flask and stirred.

After purging with nitrogen for 30 minutes, the internal temperature was adjusted to 40 ° C., and 0.6 ml of a 10% aqueous ascorbic acid solution was added to initiate polymerization. After maintaining the internal temperature at 65 ° C and carrying out the polymerization reaction for 5 hours, 20 g of polyoxyethylene nonylphenyl ether and 40 g of polyoxyethylene sorbitan trioleate were added to the obtained dispersion liquid of polymer particles having a particle size of 10 μm or less in oil. The added liquid is called sample-2. Sample-2 had a viscosity of 980 cp at 20 ° C. and a polymer molecular weight of 3 million.

(Synthesis Example-3) 1 equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introducing pipe
300g of medium oil (specific gravity 0.83, flash point 138 ° C) was charged to a 5-neck separable flask, and sorbitan monooleate 30g was added.
0.3 g of 2,2'-azobisisobutyronitrile was added and dissolved at room temperature. Separately, 133 g (50 mol%) of acrylamide and 167 g (50 mol%) of ammonium acrylate were ion-exchanged water.
After preparing a monomer solution dissolved in 325 g, it was poured into the aforementioned separable flask and stirred.

After purging with nitrogen for 30 minutes, the internal temperature was set to 60 ° C. and the polymerization reaction was carried out for 5 hours. A liquid in which 45 g of polyoxyethylene sorbitan trioleate was added and mixed to the obtained dispersion liquid of fine polymer particles having a particle diameter of 10 μm or less in oil is referred to as Sample-3. Sample-
The viscosity of 3 was 1100 cp at 25 ° C. and the molecular weight was 6 million.

(Evaluation method) The solidification property of hydrous soil is evaluated by measuring the penetration resistance value.

The method of measuring the penetration resistance value in this test is as follows.

Attach a penetration needle with a cross-sectional area of 7.5 cm ² to a penetration resistance measuring device for measuring the setting time of concrete, measure the resistance value by allowing the penetration needle to penetrate 25 mm for 10 seconds into the treated soil filled in a metal cylinder with a diameter of 15 cm .

If the penetration resistance value is 0.3 kg / cm ² or more, generally there is no significant difficulty in transportation.

(Example-1) The water-containing excavated soil collected from the residual soil storage tank of the tunnel construction work site by the earth pressure shield construction method of a certain civil engineering company was used for a test by removing coarse lumps with a 5 mm sieve.

The physical properties of the excavated soil are as follows.

Silt clay content: 70.2% Dry solid content: 40.1% Specific gravity: 1.52 Slump value: 6cm Penetration resistance value: 0kg / cm ² 3l of the above excavated soil is a tabletop universal mixer (JIS R-5201 9.
1)), the sample in the amount shown in Table 1 was added, and after kneading for a certain period of time, quicklime was added and kneading was further performed for 30 seconds, and then the penetration resistance value was measured.

The results are shown in Table-1.

When powder 1 or powder 2 was added and kneaded to the above-mentioned hydrous soil, a large amount of mamoko was generated and could not be mixed uniformly.

All additions are expressed as the weight of pure chemicals relative to the volume of water-containing residual soil.

(Example-2) To the same excavated soil as in Example-1, the same stirrer was used, the amounts of chemicals shown in Table-2 were added, and after kneading for a certain period of time, the penetration resistance value was measured.

The results are shown in Table-2.

In addition, all addition amounts are expressed as the chemical content of chemicals with respect to the volume of residual soil containing water.

[Effect of the Invention] The present invention is a calcium selected from quick lime, slaked lime and / or cement after kneading and adding a fine particle dispersion of a specific acrylic water-soluble polymer to the hydrous excavated residual soil generated by earth pressure system shield work. The present invention relates to a treating method in which a compound is added and kneaded to remove the fluidity of a hydrated soil without removing water to obtain a treated soil that can be treated as general soil.

In the fine particle dispersion, the surface of the water-soluble polymer fine particles is covered with the dispersion medium, so that even if added to the hydrated soil, no rapid dissolution / thickening occurs, and the hydrated soil is uniformly generated without the formation of mamako. Can be dispersed within.

When a calcium compound consisting of a lime-based coagulant is added after the water-soluble polymer has been adsorbed and coated on the soil particles, calcium ions are added to the carboxyl groups of the water-soluble polymer and the anionic hydrophilic groups in the soil particles, resulting in an adhesive property. It can be treated soil with no dryness. The properties of this treated soil are the same as those of ordinary soil, they do not solidify over time, and no substance that gives a feeling of foreign matter is generated in the treated soil.

Further, the fine particle dispersion of the present invention does not solidify due to moisture absorption and has a low viscosity, so that it is easy to supply a fixed amount by a pump or the like.

Claims (1)

[Claims] 1. A water-soluble polymer is added and kneaded to a hydrous excavated residual soil having a slump value of 5 cm or more generated by earth pressure system shield work, and then a calcium compound selected from quicklime, slaked lime and / or cement is added and kneaded. When the fluidity of the hydrated soil is lost without removing water, (a) the water-soluble polymer is added as a fine particle dispersion having a particle size of 100 μm or less, and (b) the addition amount of the dispersion is a 0.1~5kg to hydrous soil 1 m ³ as the polymer net amount, that amount of the calcium compound is 1~100kg to hydrous soil 1 m ^3, (c) water-soluble high in the dispersion The molecule has a carboxyl group
An anionic polyacrylamide containing 10 to 50 mol% and having a molecular weight of 1,000,000 or more, and (d) the dispersion medium constituting the dispersion is a liquid that does not dissolve the water-soluble polymer. Treatment method for residual excavated water.