JPH07136613A - Improving method for soil produced in construction - Google Patents

Abstract

PURPOSE:To improve soil texture and reutilize improved soil as re-sources by mixing water-soluble polymer powder with soil produced in construction, treating the mixture through a sieving machine and thereafter treating oversize through a disintegrating mixer, returning it to a sieving machine and mixing slime with undersize. CONSTITUTION:Surplus soil 10 such as the Kanto Loam is introduced into a hopper 20 through a lattice material 22. After water-soluble polymer powder 70 is added thereto, the mixture is mixed for a specified time in an agitating mixer 30 such as a biaxial paddle type mixer of a first step. Disintegrated granular surplus soil 10 is introduced into a sieving machine 90 and sieved. Residual soil on the sieve is introduced into a disintegrating mixer 50 such as impact mixer and soil unpassed through the sieving machine 90 is disintegrated. After the soil is disintegrated by the disintegrating mixer 50, sieving treatment is again performed. On one side, quick lime 80 is added to mixed soil under the shieve, and thereafter the mixture is introduced into an agitating mixer 30a of a second step and agitated for a prescribed time. Improved soil 100 is obtained in which quick slime 80 is mixed and particle size is regulated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving soil generated by construction, and in particular, soil generated by construction and civil engineering (hereinafter referred to as "remaining soil") is improved in soil quality and reused as a resource. The present invention relates to a method for improving construction soil that is suitable for use.

[0002]

2. Description of the Related Art Regarding the reuse of residual soil, a residual soil treatment plant using quick lime is operated for the residual soil having a relatively low water content (water content ratio of about 40% or less) and not so high in viscosity. Examples are known (for example, JP-A-5
7-121086). However, in this type of plant treatment method, for residual soil with a water content of 40% or more and high viscosity, the mixing ratio of soil stabilizers such as quick lime is made extremely high, or it is dried in the sun in advance to obtain a water content ratio. Since it cannot be treated unless the waste is reduced (for that purpose, a vast site is required), landfilling and dumping are still the main method of treatment, and only a small portion of the remaining soil is reused. Is the current situation.

[0003]

In a conventional soil improvement plant, the site cannot be wide because it is only dried in the sun. Therefore, the residual soil with a high water content generated at the site can be improved without being dried in the sun. Is realistic. However, the residual soil having a high water content has a large adhesiveness, and the soil lump tends to adhere to a mixer or the like, which makes the treatment difficult. Further, even if the treatment is forcibly performed, improvement of the CBR strength cannot be expected, and the yield as a product is poor. On the other hand, if the treatment is carried out with an extremely high addition and mixing ratio of quick lime, there is a problem that the CBR strength becomes too high and re-drilling becomes difficult. Therefore, the object of the present invention is to eliminate the problems of the above-mentioned conventional techniques, efficiently to the soil of excellent properties as improved soil without the need to pre-sun-dry the residual soil having a large water content with a large adhesiveness. It is to provide a method for improving the soil generated by construction so that it can be improved.

[0004]

[Means for Solving the Problems] To achieve the above object, according to the present invention, the construction soil is mixed with a water-soluble polymer powder by a stir mixer, and then sieved. It is characterized in that, after being applied to a sieving machine, the upper part of the sieving machine is put to a crushing and mixing machine and then returned to the sieving machine, and lime is mixed below the sieving machine with a stirring and mixing machine to obtain improved soil. The upper part of the sieve may be crushed by a crusher / mixer and then returned to the first-stage agitator / mixer to perform stirring / mixing and sieving operations.

The water-soluble polymer used in the present invention includes:
A general water-soluble polymer having a function of aggregating the soil can be used. A polymer containing a carboxyl group, which has the function of aggregating the soil,
For example, gum arabic, karaya gum, tragacanth gum,
Natural or semi-synthetic water-soluble polymer substances such as alginates, carboxymethyl cellulose and carboxymethyl hydroxyethyl cellulose, modified natural polysaccharides such as guar gum and locust bean gum, and synthetic water-soluble polymers such as boa acrylates. The substance can be exemplified.

Other synthetic water-soluble polymers include:
A copolymer of [meth] acrylic acid or a salt thereof and [meth] acrylamide, a copolymer of maleic acid or a salt thereof and vinyl acetate, a copolymer of itaconic acid or a salt thereof and [meth] acrylamide, etc. But preferably
There is a copolymer of [meth] acrylic acid or a salt thereof and [meth] acrylamide. [Meth] Acrylic acid or a salt thereof, as a [meth] acrylamide polymer,
In addition to a copolymer of [meth] acrylic acid or a salt thereof and [meth] acrylamide, a homopolymer of [meth] acrylamide may be partially hydrolyzed. Further, a copolymer obtained by combining the above-mentioned monomers may be used. The mixing residence time of the construction soil and the water-soluble polymer powder in the first-stage stirring mixer is preferably 20 seconds or more.

[0007] The lime used as an additive in the present invention includes quick lime and slaked lime, preferably quick lime. As the quick lime, commercially available one can be used. Moreover, it is also possible to use a commercially available lime-based modifier or cement-based modifier, if necessary. The amount of the water-soluble polymer and lime additive used in the present invention is not particularly limited because it varies depending on the water content ratio of the treated soil, but normally the water-soluble polymer is 0 relative to the remaining soil. ．
001 to 1.0% by weight, preferably 0.01 to 0.5
% By weight. The amount of lime added is
It is usually 0.2 to 20% by weight, preferably 0.5 to 10% by weight.

[0008] According to the present invention, the construction soil that can be expected to improve the soil quality is a soil having a high water content of 40 to 200% and a water content of 50 to 150%. It is general engineering works such as water and sewage works, road works, and residential land development works. Incidentally, the improvement of the soil according to the present invention, soft or, for the purpose of reusing the soil with a high water content ratio of high adhesiveness for construction such as backfilling, while improving the penetration strength,
It is to give fluidity like sand and to solidify.
Therefore, improving the soil does not simply solidify the soil having a high water content into a solid state so that the fluidity is lost.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a diagram schematically showing the steps of one embodiment of the residual soil improvement equipment to which the method according to the present invention is applied. First, the remaining soil 10 like Kanto Loam is hopper 20
Be thrown into. The residual soil 10 is introduced into the hopper 20 through a lattice material 22 provided on the upper portion of the hopper 20, and large lumps 24 of the residual soil 10 which are not suitable for processing are separated and removed.

The remaining soil 10 put in from the hopper 20 is
The water-soluble polymer powder 70 is added and mixed for a certain period of time using the first-stage stirring mixer 30. This stirring mixer 3
As 0, the two-axis paddle mixer shown in FIGS. 3 and 4 is preferably used. In this two-axis paddle mixer, two rotary shafts 32, 32 are rotatably supported inside a casing 31 in parallel via bearings 40, 40, and a plurality of arms 33 are provided on the outer peripheral surface of the rotary shaft 32. It has been planted. The arm 33 has 45 ° with respect to the axis of the rotating shaft 32.
The blades 34 having a pitch twisted in the direction of the angle are attached. Geared motor 3 for driving rotating shaft 32
The rotational torque of No. 5 is transmitted to the rotary shaft 32 via a roller chain 38 stretched between a drive sprocket 36 and a driven sprocket 37 connected to one rotary shaft 32. At the shaft ends of the rotating shafts 32, 32, the tuning gear 39,
Since 39 are meshed with each other, the rotating shaft 32 is adapted to rotate at the same number of rotations in opposite rotation directions.

On the other hand, the casing 31 includes the gradient adjusting mechanism 4
It is supported by 1, and the support arm 42 expands and contracts so that the entire casing 31 can be adjusted to the angle of the ascending slope from the supply side to the discharge side. Therefore, by increasing the gradient, the mixing time of the residual soil 10 and the water-soluble polymer powder 70 can be adjusted within the range of 20 seconds to 60 seconds. In such a twin-screw paddle mixer, the residual soil 10 and the water-soluble polymer powder 70 charged into the casing 31 through the supply port are continuously stirred and mixed while being transferred to the discharge side together with the rotation of the rotating shaft 32. To be done. In this case, the clods contained in the residual soil 10 are crushed between the blades 34, while foreign substances such as gravel and fragments of pavement waste mixed with the residual soil are not crushed as they are. Is discharged.

Remaining soil 1 crushed into particles by the above process
0 is put into the sieving machine 90, and a sieving operation is added. The residual soil on the sieve is put into the disintegration mixer 50 to disintegrate the soil that has not passed through the sieving machine 90. Then, after crushing with the crushing mixer 50, a sieving operation is performed. Alternatively, after being crushed by the crusher / mixer 50, the crusher / mixer 50 is returned to the agitator / mixer 30 to undergo agitation / mixing and sieving operations. As the crushing mixer 50, an impact mixer shown in FIG. 5 is preferably used. The mixed soil is charged into the casing 51 of the impact mixer through a charging port 52 opened on the upper surface thereof. The mixed soil falls on a striking plate 55 mounted at equal intervals through a protector 56 on the outer peripheral edge of a rotor disc 54 attached to a horizontal main shaft 53, is hit by the striking plate 55, and is hit by the rotor disc 54. Flexible elastic disintegration plates 57, 5 vertically installed so as to face each other.
It is supposed to scatter toward 7. Elastic disintegration plate 57
Has its lower end fixed to the side surface of the casing 51 via a cushioning member 58 made of rubber or the like. On the other hand, the upper ends of the elastic crushing plates 57 are connected to crushing plate oscillating devices 59 that give oscillating bending motion to the elastic crushing plates 57, respectively. The crushing plate rocking device 59 is connected to a rocking link 63 via a link member 62 to a crank 61 that is driven to rotate by a drive motor 60. Therefore, since the rocking link 63 rocks around the fulcrum 64 by the crushing plate oscillating device 59, the mixed soil, which tends to adhere and grow when it collides with the elastic crushing plate 57, is unraveled and It is sufficiently crushed and discharged from the lower outlet. By using such an impact mixer, the sieving machine 9
Even if there is a considerable amount of lumps on the sieve that did not pass 0,
By applying a mechanical impact, it is possible to disintegrate into fine particles as fine as possible.

Next, quicklime 80 is added to the mixed soil under the sieve, and the mixture is put into the second-stage stirring mixer 30a.
The aforesaid two-axis paddle mixer is preferably used as this agitating mixer 30a. Stirring is performed for a predetermined time by the stirring mixer 30a, and the quicklime 80 is mixed to obtain the improved soil 100 having the adjusted grain size.

Next, the test results of the embodiment conducted by using the soft Kanto loam having a water content of 101% as the residual soil through the above steps are shown below. In this test, the water-soluble polymers used were the polymers shown in Table 1 below.

[0015]

[Table 1] Example 1a The residual soil and the water-soluble polymer A were mixed in the first stage paddle mixer 3
Stir-mixing with 0 for 60 seconds gave a granular mixed soil. Then, it is passed through a sieving machine 90 with a mesh of 13 mm,
While adding 3% by weight of quick lime to the mixed soil under the sieve that passed through the sieve, the mixture was stirred and mixed by the second stage paddle mixer 30a for about 15 seconds. On the other hand, the excess mixed soil that did not pass through the 13 mm sieve was applied to the impact mixer 50 and then returned to the sieving machine 90 again. In this way, improved soil having an average particle size of 3 mm and exhibiting sandy fluidity was obtained at a productization rate of 96%. About this improved soil, JISA1211CB
According to the R test method, the measured CBR value was 8.5% (penetration strength was 116 Kg / cm 2). The CBR value of the raw material soil was too weak to measure. Also,
The water permeability of the improved soil was good and was similar to that of river sand.

Example 1b A test was conducted under the same conditions as in Example 1a except that the stirring and mixing time in the first stage paddle mixer 30 was shortened to 30 seconds. The commercialization rate was 91%, the CBR value of the improved soil was 8.3% (penetration strength was 114 Kg / cm2), and improved soil with good water permeability could be obtained.

Example 1c On the other hand, when the stirring and mixing time in the first stage paddle mixer 30 was further shortened to 15 seconds and a test was conducted under the same conditions,
Due to the poor granularity of the improved soil, adhesion of the mixed soil to the sieving machine 90 was observed. In addition, there was a large amount of excess in the sieving machine, which resulted in a low commercialization rate of 85%. CBR value of the improved soil is 6.5% (penetration strength is 89 kg / cm
2), and the water permeability was not so good at a value intermediate between sand and soil.

Example 2 A test was conducted under the same conditions as in Example 1a except that the polymer B was used in place of the water-soluble polymer A. As a result, good improved soil was obtained, and the commercialization rate was 95%. Met. CB of improved soil
The R value was 8.6% (penetration strength was 118 kg / cm2), and the water permeability was good. Example 3 A test was conducted under the same conditions as in Example 1a except that the polymer C was used instead of the water-soluble polymer A. Commercialization rate is 92
%, The CBR value of the improved soil is 8.9% (penetration strength is 122
Kg / cm2), and improved soil having good water permeability was obtained. Example 4 A similar test was conducted by adding sodium alginate-H as a water-soluble polymer in an amount of 0.2% by weight based on the residual soil. The commercialization rate was 89%. CBR value of the improved soil is 8.0%
(Penetration strength was 122 kg / cm2), and improved soil with good water permeability was obtained. Comparative Example 1 On the other hand, when the same test as in Example 1 was conducted on the sieve passed through the sieving machine 90 without using the impact mixer 50, the productization rate was extremely low at 61%. However, the physical properties of the improved soil obtained were very good, the CBR value was 8.8% (penetration strength was 121 kg / cm2), and the water permeability was also good.

Comparative Example 2 When a test was conducted under the same conditions as in Example 1 except that the polymer was not used, a clod of soil adhered to a paddle mixer or the like and could not be treated.

The above test results are summarized in Table 2.

[0021]

[Table 2] From the above test results, the water-soluble polymer powder and the residual soil were first
After stirring and mixing for 20 seconds or more with the paddle mixer 30 of the first stage, sieving is performed, quick lime is added under the sieve, and the mixture is stirred and mixed by the paddle mixer 32 of the second stage to obtain fluidity with an average particle diameter of 3 mm. It can be seen that an improved soil with sandy water permeability can be formed. Further, in order to improve the commercialization rate, a process of mechanically crushing and mixing the sieve on which the sieving machine 90 is applied with the impact mixer 50, and then returning to the sieving machine or the agitating mixer is performed. It was also found to be effective.

[0022]

As is apparent from the above description, according to the present invention, the soil is granulated by adding the water-soluble polymer, and the adhesion between soil particles is prevented by adding lime. It is possible to increase the efficiency of soil improvement by lime by a synergistic effect while imparting sand-like fluidity to the soil. For this reason, it is possible to treat the residual soil with a high water content ratio, which is difficult to improve by mixing lime alone into conventional soil, and to treat it with a high commercialization rate. Since it has good strength, it can be reused as a resource by efficiently improving construction soil with a high water content, which has been discarded and discarded because it cannot be reused. Further, since the obtained improved soil has good water permeability, it can be reused, for example, for water tightening work on the lower part of the pipe or the like.

[Brief description of drawings]

FIG. 1 is a process diagram showing a process of a method for improving construction soil according to the present invention.

FIG. 2 is a schematic diagram showing a process according to an embodiment of a residual soil improvement facility to which the method for improving construction soil according to the present invention is applied.

FIG. 3 is a plan view of a twin-screw paddle mixer used as a stirring mixer.

4 is a side view of the twin-screw paddle mixer in FIG.

FIG. 5 is a side view showing the structure of an impact mixer used as a crushing mixer.

[Explanation of symbols]

 10 Remaining soil 20 Hopper 30 Stirring mixer 32 Rotating shaft 34 Blade 41 Gradient adjusting mechanism 50 Crushing mixer 52 Input port 54 Rotor disk 55 Hitting plate 57 Elastic crushing plate

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[Procedure amendment]

[Submission date] February 18, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

On the other hand, the casing 31 includes the gradient adjusting mechanism 4
It is supported by 1, and the support arm 42 expands and contracts so that the entire casing 31 can be adjusted to the angle of the ascending slope from the supply side to the discharge side. Therefore, by increasing the gradient, the mixing time of the residual soil 10 and the water-soluble polymer powder 70 can be adjusted from about 15 seconds to about 60 seconds. In such a twin-screw paddle mixer, the residual soil 10 and the water-soluble polymer powder 70 charged into the casing 31 through the supply port are continuously stirred and mixed while being transferred to the discharge port together with the rotation of the rotating shaft 32. To be done. In this case, the clods contained in the residual soil 10 are crushed between the blades 34, while foreign substances such as gravel and fragments of pavement waste mixed with the residual soil are not crushed as they are. Is discharged.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area C09K 17/06 P 17/22 P 17/42 P 17/48 P 17/50 P E02D 3/00 3/12 E02F 7/00 D // C09K 103: 00 (72) Inventor Toshi Nishijima 336 Ozaki-cho, Hachioji-shi, Tokyo Tokyo Environmental Service Co., Ltd. (72) Inventor Shigenori Nagaoka 1780 Uetakano, Yachiyo-shi, Chiba Kawasaki Heavy Industries, Ltd., Yachiyo Factory (72) Inventor Kenji Mori, 1000 Kamoshida-cho, Midori-ku, Yokohama, Kanagawa Sanryo Kasei Co., Ltd.

Claims (4)

[Claims] 1. Construction-generated soil and water-soluble polymer powder are mixed by a stirrer, and then sieved, and then the sieve is crushed and mixed, and then returned to the siever, A method for improving construction-generated soil, which comprises mixing lime under a sieve with a stirring mixer to obtain improved soil. 2. The method for improving construction soil according to claim 1, wherein the sieve top is crushed by a crushing mixer and then returned to the first-stage stirring mixer. Improvement method. 3. The method for improving construction soil according to claim 1, wherein the mixing residence time of the construction soil and the water-soluble polymer powder in the first-stage stirring mixer is 20 seconds or more. A method for improving soil generated from construction, which is characterized by the following. 4. The method for improving construction-generated soil according to any one of claims 1 to 3, wherein the water-soluble polymer is a carboxyl group-containing water-soluble polymer.