JPH1099899A - Treatment of soft soils - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and quantitatively supply soft soils to a continuous treatment plant by adding water to weak soils to adjust a slump value and mixing these soft soils with a water-soluble polymeric substance by a stirring mixer and subsequently bringing the resulting mixture into contact with lime by a crushing type mixer and classifying the same by a sieving machine to collect minus sieve matter to age this matter. SOLUTION: Soft soils 10 are mixed with water 23 by a rotary bucket 25 within a pit 20. Soft soils regulated in moisture are charged in a hopper 35 by a backhoe and quantitatively sent to a stirring mixer 41 by a hose pump 38 to be mixed with a water soluble polymer 43 and the treated matter is sent to a vibrating feeder 50 and lime 52 is sprinkled over the treated matter. Subsequently, this treated matter is sent to a sieving machine 60 by a belt conveyor 55 and classified according to a particle size to be stored in the open air. By taking a day or more as an open-air storage ageing period, the water insolubilizing reaction of the water soluble polymer is completed and pozzolan solidifying reaction by quick lime is performed to obtain regenerated soil 62 excellent in strength and water permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to excavated soil generated in civil engineering and construction work, boring, and the like, and sediment and sludge generated during dredging work in rivers, lakes, marshes and harbors (hereinafter referred to as soft earth). For reuse as a resource.

[0002]

2. Description of the Related Art As a method of treating soil and sediment such as construction-generated soil and dredged soil as resources, there are methods using limes such as quicklime and slaked lime, methods using cement-based solidifying materials, and other methods using water-soluble materials. There is known a method in which a granular polymer is added to granulate, and then quick lime or slaked lime is added to solidify.

[0003]

Regardless of which method is used, a continuous processing plant will be used to carry out large-scale processing as a business, but the most problematic here is the removal of earth and sand. This is a method of supplying quantitatively to a continuous processing plant. Generally, among the soils generated from construction, those having a water content of less than 20% for sandy silts and those having a water content of less than 40% for silt clays have few difficulties in handling,
Construction soils treated by a treatment method using a water-soluble polymer substance are soft earths with a high water content and often have tackiness. Therefore, belt feeders, screw feeders, rotary feeders It is difficult to cut out the sediment accumulated in the hopper with a general-purpose feeder such as a vibratory feeder (Eurus feeder) and send it to a processing machine quantitatively. Even for dredged soils with a water content of more than 600%, they have fluidity and there are few difficulties in handling, but the negative pressure suction type developed to minimize the amount of accompanying water as much as possible Among dredged sludges, non-fluid ones and high-water dredged sludges with a water content of more than 600%, which are dried in the surrounding embankment in the sun and are no longer flowable, are generally used. It is difficult to feed the processing machine quantitatively with this feeder.

[0004]

Means for Solving the Problems The inventors of the present invention have intensively studied a method for quantitatively supplying soft earth in the case of a treatment method using a water-soluble polymer substance. Water is added to the soil to make it 30 cm thick, and the soil is made to have fluidity. It is quantitatively stirred and mixed with pumps such as a hose pump and a mono pump, or a closed general-purpose feeder such as a screw feeder and a rotary feeder. I thought of sending it to. That is, the gist of the present invention is to adjust the slump value by adding water to soft earth, then mix with a water-soluble polymer substance with a stirring mixer,
The present invention relates to a method for treating soft earth, which comprises contacting and reacting lime with the surface of a grain using a non-crushing type mixer, further classifying the lime with a sieving machine, collecting the sieved material, and curing the sieved material.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The present invention treats soft earth, that is, excavated soil generated in civil engineering construction work or boring, sediment and sludge generated during dredging work such as rivers, lakes, marshes and harbors, for reuse as resources. About the method. The slump value of the soft earth which is the object of the present invention varies depending on the soil properties, but is generally less than 20 cm. Here, the slump value is a value measured by a slump test method for JIS A1101 concrete. In addition, the slump value is 20
Add water to ３０30 cm. If the amount of water is too large and the slump value exceeds 30 cm, the strength of the final product may decrease, and a predetermined CBR value may not be obtained. Here, the CBR value is based on the JIS A1211 subgrade soil bearing capacity ratio test method. Mixing of soft earth and water is used in construction machinery,
For example, it is good to use a rotary bucket having a backhoe or hackhoe with blades for crushing, or a batch type mixer, for example, a mortar mixer.

The pumps used in the present invention are not particularly limited, and are generally used for high-viscosity liquids.
A liquid that can be sent even if a solid mass of about 5 cm is mixed therein, such as a hose pump and a mono pump. As the closed general-purpose feeder used in the present invention,
There is no particular limitation, and those usually used, those containing a large amount of water, having tackiness, and capable of being supplied even when a bulk solid of about 3 to 5 cm are mixed, such as a screw feeder and a rotary feeder And the like.

The water-soluble polymer used in the present invention includes, as natural substances, seed polysaccharides such as guar gum, roasted guar gum, and locust bingham; resin polysaccharides such as arabinogalactan gum and arabia gum; alginate; Animals such as seaweed polysaccharides, fruit polysaccharides such as pectin, syllum gum, rhizome polysaccharides such as starch and konjac, fiber polysaccharides such as cellulose, microbial xanthan gum, xan coat, xanflow, curdlan, succinoglucan There are gelatin, casein, albumin, shrack and the like. Further, as a semi-synthetic type, starch derivatives, guar gum derivatives obtained by subjecting starch, guar gum, roasted guar gum, cellulose, alginic acid, etc. to oxidation, methylation, carboxymethylation, hydroxyethylation, phosphorylation, etc. , Roasted guar gum derivatives, cellulose derivatives, alginic acid derivatives and the like. Furthermore, as a synthetic system,
Polymer of polyacrylamide, polyvinyl alcohol, maleic anhydride or a salt thereof, polyacrylate, polystyrenesulfonate, polyacrylate, polyvinylsulfonate, polymaleate, acrylamide with acrylic acid or a salt thereof There is a polymer (a partial hydrolyzate of a polymer of acrylamide alone).

The water-soluble polymer used in the present invention may be used in the form of a powder or a liquid in which the water-soluble polymer is dispersed in a liquid in which the water-soluble polymer is not dissolved.
The powdery form is not particularly limited, and may be fine powder, granular form, or granular form. Any commercially available powdery product can be used, but 30 mesh or more accounts for 50% or more. Such coarse particles are desirably avoided because they have a slow dissolution rate and a long kneading time, except for those subjected to a surface treatment for easy solubilization.

The lime used in the present invention is an alkaline earth metal-containing substance which reacts with a water-soluble polymer substance to make it water-insoluble, such as quick lime, slaked lime, lime-based solidifying agent, cement-based solidifying agent and the like. Anything can be used, but quicklime, which can be expected to have a dehydration effect and a solidification effect by the pozzolanic reaction, is particularly desirable. The particle size is preferably 1 mm or less, and preferably finely pulverized.

Hereinafter, the method of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of the process of the present invention. The soft soil 10 is mixed with water 23 by a rotary bucket 25 in a pit 20 dug in the ground. At this time, large gravel and concrete lumps
Removed. The soft soil whose water content has been adjusted is fed into a hopper 35 by a backhoe (yumbo) 30, and is then quantitatively sent to a stirring mixer 40 by a hose pump 38. In the stirring mixer, the water-soluble polymer 43 is added, and the mixing is sufficiently performed. If the mixing time is too short, water absorption, thickening, reforming, and granulation are insufficient, and if too long, on the other hand, once formed particles may be broken, and the working efficiency may not be improved. is there. Therefore, the mixing time is 30 seconds or more and 3
Within minutes is desirable. The treated material is then sent to a vibrating feeder 50, where lime 52 is sprinkled. Sprinkle the lime with a swing chute so that it spreads throughout the processed material. The treated material is then sent to a sieving machine 60 by a belt conveyor 55, where it is divided into two or three stages of granularity depending on the use of the reclaimed soil, and is piled up into a piled reclaimed soil 62. The water-insolubilization reaction of the water-soluble polymer with lime is completed by taking the open stacking curing period of 1 day or more, desirably 3 days or more, and the pozzolan solidification reaction by quick lime proceeds, and the treated product has sufficient strength. It is reborn as a regenerated soil with excellent moisture permeability.

The amount of the water-soluble polymer used in the present invention is
It is appropriate that the range of 0.02 to 0.3% by weight in terms of the pure content in terms of the weight of the soft earth in the hydrated state is appropriate.
1 to 5% by weight based on the weight of soft earth
Range is applicable. Since the amount of each addition differs depending on the water content of the target soft earth, the soil quality, and the desired strength of the reclaimed soil,
Perform a lab test in advance to determine the optimal amount to add.

[0012]

The present invention will be described in more detail with reference to Examples 1 to 4 and Comparative Examples 1 and 2. However, the present invention is not limited to this. Example 1 A sandy soil having a moisture content of 18% and a slump value of 0 cm (sand content of 83% by weight, silt clay content of 17% by weight) was treated according to the flow sheet of FIG. In addition, the water content refers to a value obtained by multiplying the ratio of the weight of water to the solid content by 100, and the water content was measured according to JIS A-1203 "Test Method for Water Content of Soil". First, water is added to 100 parts by weight of sandy soil.
7 parts by weight were added and sufficiently stirred with a rotary bucket.
The slump value after stirring was 25 cm. Next, this was put into a hopper by a yumbo, and sent from there to a paddle mixer by a hose pump at a speed of ₃ m ₃ / hour. Using a paddle mixer, 0.1 part by weight of a copolymer of acrylamide and sodium acrylate in a molar ratio of 7: 3 (weight average molecular weight: 12,000,000) was added to 100 parts by weight of sandy soil, and mixed for 1 minute. Next, send it to the vibrating feeder,
Therefore, 3 parts by weight of quicklime was sprinkled on 100 parts by weight of the sandy soil. Quicklime spreads throughout the processed material,
I sprinkled it using a swing chute. Subsequently, the treated product was sent to a sieving machine, where it was sieved to a two-stage particle size with a 6 mm screen, and then cured for 3 days. The yield of a processed product having a particle size of 6 mm or less is 82%, JIS A121.
CBR value based on 1 subgrade soil bearing capacity ratio test method is 16.
7%, the water permeability was 0.35 cm / s based on JIS A1218 soil water permeability test method.

Example 2 A sun dried product of a certain port dredging bottom mud having a water content of 309% and a slump value of 14 cm was treated in accordance with the flow sheet of FIG. First, 9.4 parts by weight of water was added to 100 parts by weight of the sun-dried bottom mud, and the mixture was sufficiently stirred with a rotary bucket. The slump value after stirring was 23 cm. Hereinafter, the treatment was performed in exactly the same manner as in Example 1. The yield of the treated product having a particle size of 6 mm or less was 89%, the CBR value was 15.9%, and the water permeability was 0.094 cm / s.

Example 3 10.9 parts by weight of water was added to 100 parts by weight of viscous soil mixed with gravel (42% gravel, 40% sand, 18% silt clay) having a water content of 19% and a slump value of 0 cm. Stir well in bucket. The slump value after stirring was 24 cm. Hereinafter, the treatment was performed in exactly the same manner as in Example 1. 6mm
The yield of the processed product having the following particle size is 84%, and the CBR value is 1
3.4% and a water permeability of 0.28 cm / s.

Example 4 Cohesive soil having a water content of 43% and a slump value of 0 cm (sand content: 10%)
%, Silt clay content 90%) and water to 15.3 parts by weight.
The mixture was added by weight and sufficiently stirred with a rotary bucket. The slump value after stirring was 21 cm. Hereinafter, Example 1
Treated in exactly the same way. The yield of the treated product having a particle size of 6 mm or less was 80%, the CBR value was 12.5%, and the water permeability was 0.19 cm / s.

Comparative Example 1 Sandy soil having a water content of 18% and a slump value of 0 cm (sand content 83
%, Silt clay content 17%) were treated according to the flow sheet of FIG. First, 15 parts by weight of water was added to 100 parts by weight of Kanto loam and sufficiently stirred with a rotary bucket. The slump value after stirring was 34 cm. Less than,
Treated in exactly the same way as in Example 1. The yield of the treated product having a particle size of 6 mm or less was 89%, the CBR value was 4.2%, and the water permeability was 0.18 cm / s.

Comparative Example 2 Sandy soil of Example 1 (sand content: 83%, silt clay content: 17%)
At the time of the treatment, the water was not added to the hopper 35 by the backhoe (yumbo) 30 shown in FIG. 1, and from there, the attempt was made to quantitatively send the mixture to the mixer 40 by using a belt feeder instead of the hose pump 38. However, a mass of shelves formed at the bottom of the hopper 35, making quantitative supply impossible.

Examples 1, 2, and 3 all have sufficient strength as a reclaimed soil, exhibit a permeability similar to that of coarse sand, have a smooth processing flow, and can be processed economically and efficiently. I was able to confirm that. On the other hand, Comparative Example 1
The value was as small as 4.2%, and the strength was insufficient for use as recycled soil. Comparative Example 2 proved that efficient treatment was not possible without adding water.

[0019]

According to the method for treating soft earth of the present invention, soft earth can be easily and quantitatively supplied to a continuous treatment plant.

[Brief description of the drawings]

FIG. 1 is a flow sheet illustrating the present invention.

FIG. 2 (A) is a screw feeder for supplying a fixed amount of the soft earth after water addition used in the present invention to a stirring mixer, and FIG. 2 (B) is a rotary feeder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Soft earth 20 Pit 23 Water 25 Rotary bucket 30 Backhoe (Yumbo) 35 Hopper 38 Hose pump 40 Stirrer / mixer 43 Water-soluble polymer 50 Vibrating feeder 52 Lime 55 Belt conveyor 60 Sieving machine 62 Non-reclaimed soil

Claims (4)

[Claims] An excavated soil having a slump value of less than 20 cm, excavated soil generated in civil engineering construction and boring, and sediment and sludge (hereinafter referred to as soft earth) generated in dredging work of rivers, lakes, marshes and harbors. After adding water and adjusting the slump value, mixing with a water-soluble polymer substance with a stirring mixer, then contacting lime with the surface of the particles with a non-crushing type mixer,
A method for treating soft earth, comprising reacting, classifying with a sieving machine, collecting sieving, and curing the sieving. 2. A slump value is adjusted by adding water to the soft earth having a slump value of less than 20 cm.
2. The method for treating soft earth according to claim 1, wherein the water is quantitatively supplied to the stirring mixer by a pump such as a mono pump. 3. A slump value is prepared by adding water to the above soft earth having a slump value of less than 20 cm, and then quantitatively supplied to a stirring mixer by a closed general-purpose feeder such as a screw feeder or a rotary feeder. The method for treating soft earth according to claim 1. 4. When preparing a slump value by adding water to the soft earth having a slump value of less than 20 cm, water is added so that the slump value of the soft earth after adding water is 20 to 30 cm. The method for treating soft earth according to claim 1, wherein the method is added.