JP2003301176A - Method for improving earth and sand and aqueous solution of polymer improver for earth and sand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for improving earth and sand which can easily granulate earth and sand and stabilize them. <P>SOLUTION: An aqueous solution 14a of a polymer-based improver 10 is obtained by stirring and mixing the polymer-based improver 10 with water 11 by using a stirrer 13. Concretely, the polymer-based improver 10 of not more than 0.5 by weight is mixed with water 11 of 100 by weight. This is sprinkled on not yet improved soil 19 and then it is stirred by using digging vanes 21 for improvement. Next, a powdery lime-based soil improver is sprinkled on the earth and sand followed by mixing and stirring again. In the first process, fine earth and sand particles are granulated into sand-like state. In the second step, the earth and sand come to be in the state that the earth and sand are wafered with the powdery lime-based sand improver whereby the improved earth and sand become so stable that they do not easily collapse even when there is an external effect such as rain. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earth and sand improving method using a polymer-based improver, and an aqueous solution of the earth and sand improving agent used in such an earth and sand improving method.

[0002]

2. Description of the Related Art There is known a method in which a cement-based improving material is mixed with earth and sand in order to improve the earth and sand to have a strength that can be used as an embankment material and a roadbed material or to aggregate the earth and sand. It is said that this method can increase the strength of the earth and sand or aggregate the earth and sand.

[0003]

However, the cement-based improving material and the improving method using the same have the following problems.

In the method of mixing powdery cement-based improving material with earth and sand, since the earth and sand congeal in the form of rocks due to the hydration of cement by the water content in the earth and sand, it is necessary to make the improved earth fine. It was necessary to work to crush the rock and sand, that is, to loosen it. That is, it is uneconomical because a step of crushing the rock mass-like sand after the improvement is necessary in addition to the improvement of the earth and sand, which is troublesome twice.

In addition, in the improvement method of mixing the powdery cement type improving material, the soil improvement machine and the soil improvement tank have been used to improve the earth and sand. This method requires the steps of collecting and transporting the soil to be improved, the improved soil process, and the improved soil transport process. For this reason, not only the sediment improvement process increases and the construction cost becomes high, but also it cannot be applied to the work of directly agglomerating the soil that exists in a plane, for example, the soil such as cultivated land or bare land on site. It was

[0006] As a specific example, the Kunigami merge, which is generally called red soil in Okinawa, has very fine soil particles.
Rainwater flows out as surface water of bare land and cultivated land rather than being absorbed by the ground. At this time, the runoff rainwater dissolves fine soil particles, becomes red water and runs out, polluting seawater and the like, causing serious environmental problems such as coral reef death (red water runoff problem).

In order to solve such a problem, it is desirable that the soil of the bare land and the cultivated land be in the form of aggregates having a good drainage property. However, as described above, in the improvement of cultivated land and the like by the conventional cement-based soil improvement material, there is a problem with the improved soil that solidifies in the shape of a rock mass, and the improved soil was substantially unusable as cultivated soil. .

Further, in order to aggregate the sand and sand, in addition to the case of using the above-mentioned cement-based improver, there was also a case of using a lime-based soil-sand improver and a gypsum-based sand-sand improver. The lime-based soil improvement material and gypsum-based sediment improvement material used as a method of liquefaction are generally targeted for high-moisture content sediments, and all of the sediment improvement materials are highly water-absorbing and have their own water content. , It is a method of agglomerating sediment, and is suitable for sediment with a high water content exceeding the plastic limit, but as a means to improve sediment in a natural state, such as cultivated land, bare land, etc. into aggregated sand Was not suitable.

Therefore, the present invention provides a method for improving sediment and an aqueous solution of a polymer improving agent, which has various advantages such as the above-mentioned problems, easy and stable aggregation of sediment, and the like. Is intended.

[0010]

The method for improving sediment according to claim 1 is characterized in that an aqueous solution of a polymer-based sediment improving agent is sprinkled on the earth and mixed and stirred.

The sediment improvement method according to a second aspect is characterized in that a powdery polymer-type soil improvement agent is sprinkled on the sediment and mixed and stirred.

The method for improving sediment according to claim 3 is the method for improving sediment according to claim 2, characterized in that water is sprayed on the sediment.

According to a fourth aspect of the earth and sand improving method, an aqueous solution of a polymer-type earth and sand improving material is sprinkled on the earth and sand, mixed and stirred, and then a powdery lime type earth and sand improving material is further sprinkled on the earth and sand. It is characterized by mixing and stirring.

According to a fifth aspect of the earth and sand improving method, an aqueous solution of a polymer-type earth and sand improving material is sprinkled on the earth and sand, mixed and stirred, and then a powdery gypsum-based earth and sand improving material is further sprinkled on the earth and sand. It is characterized by mixing and stirring.

According to a sixth aspect of the earth and sand improving method, an aqueous solution of a polymer-type earth and sand improving material is sprayed on the earth and sand, mixed and stirred, and then a powdery cement-based earth and sand improving material is further applied to the earth and sand. It is characterized by mixing and stirring.

According to a seventh aspect of the earth and sand improving method, an aqueous solution of a polymer-type earth and sand improving material is sprinkled on the earth and sand and mixed and stirred, and then a compost is further sprinkled on the earth and sand and mixed and stirred. To do.

The aqueous solution of the polymer-based sediment improver according to claim 8 is characterized in that the weight ratio of the polymer-based soil improver is 0.5 or less with respect to 100 of water.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A first example will be described. As shown in FIG. 1, in the first step, a predetermined amount of the polymer-based improving material 10 and water 11 are put into a stirring device 13 having a stirring blade 12 and stirred and mixed to prepare an aqueous solution 14a of the polymer-based improving material. And Specifically, 0.5 or less of the polymer-based improving material 10 is mixed with 100 parts by weight of water 11. This aqueous solution 14a becomes a viscous, thick paste. This is storage tank 1
For No. 5, it is sent out through the hose 17 by the pressure feed pump 16 and sprayed on the unmodified soil 19 which is the target by the nozzle 18. The aqueous solution may be placed in a container and sprayed manually. You may spray directly from the container installed in the cultivator. Then, the excavation blade 20 (backhoe bucket,
A soil conditioner or stabilizer may be used) to stir and improve the soil.

Next, in the second step, powdery lime soil conditioner is sprinkled on the mixed and stirred earth and sand and mixed and stirred again. In the first stage, the sand that has been agglomerated by mixing and stirring the aqueous polymer-based soil improving agent solution is in an appropriately moist state. By mixing and stirring the powdery lime-based earth and sand improver in the second step, the lime-based earth and sand improver absorbs the water content of the earth and sand improved in the first step, and is improved into a dry, crumbled aggregate. .

As described above, when the aqueous solution of the polymer-based sediment improving agent is sprayed on the earth and mixed and stirred, the fine earth particles of the earth and sand are aggregated into sand. The earth and sand aggregated in the first step is in a state of being obfuscated by the powdery lime-based earth and sand improving material in the second step, so that it is not easily collapsed even if there is an external influence such as rainfall water. The improved soil can be obtained.

In the earth and sand improving method, instead of the powdery lime type earth and sand improving material to be sprayed in the second step, a powdery gypsum type earth and sand improving material or a powdery cement type earth and sand improving material is sprayed and mixed and stirred. Even if it does, it can be improved to aggregated sand.

The improving material used in the second step can be selected according to the properties of the soil before the improvement and the improving application. For example, when the soil (original soil) is acidic and the improved soil is desired to be neutral or alkaline, the improving agent used in the second step includes a powdery cement-based soil improving agent or a powdery lime-based soil improving agent. Materials can be used.

When it is desired to improve the earth and sand without changing the properties of the earth and sand (original earth), the object can be achieved only by the first step of spraying an aqueous solution of a polymer-type earth and sand improver on the earth and mixing and stirring. If the powdery gypsum-based earth and sand improving material is used in the second step, the effect of further stabilizing the soil particles and improving the drainage, air permeability and water retention of the improved earth and sand can be obtained.

Further, according to the present example, the aqueous solution of the polymer-based sediment improving agent sprinkled on the earth and sand in the first step has the effect of improving the handling of the rotary blades for mixing and stirring the earth and sand. In particular, when the original soil (sand) is hard, when the polymer-based improving agent aqueous solution is sprayed and cultivated (stirred), the resistance of the stirring blade during excavation rotation is very small, and the soil is finely crushed. However, when the powdery lime soil conditioner is sprayed and stirred first, the rotation of the stirring blade becomes very heavy, and since the earth and sand do not break, large lumps remain and the improvement effect becomes extremely small.
Therefore, the order of use of the two types of modifiers in this example is:
As described above, it is necessary to first spray the aqueous solution of the polymer improving material and stir, and then spray the powdery lime soil improving agent and stir.

In the method of the present example, when the amount of the polymer-based soil improving material 10 is more than 0.5%, the polymer-based soil improving material remains in the form of agar or in an aqueous solution, Further, the debris of the polymer-based soil improving material remains in the improved soil and is not uniformly mixed, which is inconvenient.

The second example will be described. In this example, in place of the powdery cement-based earth and sand improver, the powdery lime-based earth and sand improver, and the powdery gypsum-based earth and sand improver which are sprayed in the second step in the first example, compost is sprayed. It is characterized by mixing by mixing.

According to this example, it is possible to increase the porosity of upland soil, improve water absorption and water retention, and provide an environment suitable for growing crops.

A third example will be described. This example is a method of spraying an aqueous solution of a polymer-based earth and sand improving material on earth and sand and mixing and stirring in the first step, and spraying an aqueous solution of a cement-based earth and sand improving material and further mixing and stirring in the second step. The first step is the same as the first example. Next, as a second step, the cement-based sediment improvement material and water are mixed with each other by using an apparatus similar to that shown in FIG.
Stir and mix at a weight ratio of 1 to prepare an aqueous solution. As in FIG. 1, this is put into a storage tank, sent out through a hose by a pressure feed pump, and sprayed with a nozzle onto the earth and sand improved in the first step. The aqueous solution may be placed in a container and sprayed manually. Then, the earth and sand are stirred again by the excavating blades of the cultivator,
Improve.

According to the present example, the polymer-based soil improvement material (polymer-based soil improvement material) aggregates fine soil particles into agglomerates, and the cement-based soil improvement material is agglomerated soil. It gives strength by the solidification action of cement. The improved soil improved by both of the improving materials does not become a rock mass like the earth and sand improved by a conventional cement-based improving material, but becomes a sand from a sandy to a small gravel-sized aggregate.

The aqueous solution of the polymer-based soil improving material 10 sprinkled on the soil in the first step has the effect of improving the handling of the rotary blades for mixing and stirring the soil. Especially the original soil (earth and sand)
If the soil is hard, the resistance of the stirring blade during excavation rotation is very small and the sand is crushed finely when the polymer improving agent aqueous solution is sprinkled (stirred). However, when an aqueous solution of the cement-based soil and sand improving material is first sprayed and stirred, the rotation of the stirring blade becomes very heavy, and since the sand and sand are not crushed, a large amount of lumps remain and the improving effect becomes extremely small. Therefore, the order of using the two kinds of aqueous solutions in this example is that, as described above, the polymer-based improvement material aqueous solution is first sprayed and stirred, and then the cement-based earth and sand improvement material aqueous solution is sprayed and stirred. is necessary.

Further, according to the present method, it is possible to directly improve the ground and sand into agglomerates on the spot without the trouble of transporting the earth and sand existing in a plane separately to the equipment for improvement and then returning to the original position. You can Therefore, the soil improvement work can be performed in a short time and at a low cost with a simpler device than the conventional one.

In the method of this example, the amount of the aqueous solution is adjusted within the plastic limit depending on the natural water content of the earth and sand. When it is desired to increase the strength of aggregated sediment, increase the amount of cement-based sediment improvement solution. However, the sum of the amount of water in the polymer-based sediment improvement solution and the amount of water in the cement-based improvement agent should be kept within the plastic limit of the improved sediment.

When the amount of the improving agent aqueous solution sprayed on the earth and sand becomes large, and mud becomes mud when the plastic limit is exceeded, in the method of this example, each aqueous solution of the polymer-based earth and sand improving agent is added. Also, the water content of the improved soil should not exceed the plastic limit. For example, in the case where the water content of the plastic limit is 50% and the water content of the improvement target sand is 30%, the water content of the polymer-based earth and sand improving agent aqueous solution and the cement-based sand improvement material are assumed to be 30%. The total amount of water in the aqueous solution is 540k
It is better to make it less than g. In the clay-silt type sediment, when the water content of the improved sediment is approximately 40%, the aggregate of the sand is efficiently formed. It is necessary to investigate in advance the water content of the target soil and to adjust the amount of aqueous solution of each soil improver to be mixed and stirred. It cannot be applied to sediments with a water content exceeding the plastic limit. Here, in the mixing of the polymer-based soil and sand improving agent aqueous solution and the cement-based soil and sand improving agent aqueous solution, when the mixing amount of the cement-based soil and sand improving agent aqueous solution is increased, the strength of the aggregated soil particles becomes high. In addition, in the mixing of the polymer-based soil improvement agent aqueous solution and the cement-based soil improvement agent aqueous solution, the aggregate particle size of the improved soil increases as the water content of the improved soil approaches the plastic limit, including the water content of the soil to be improved. It is good that the improved soil is clenched with your hands to form a dumpling, and the dumplings are crushed with your fingers on the palm. The improved soil is naturally dried and aggregates appropriately from fine sand to small gravel, and has good water permeability. Immediately after the improvement, the improved soil is properly moist. When compacted in this state, the improved soil becomes concrete due to the cement solidification action of the cement-based soil improvement material.

Therefore, in the method of this example, it is desirable to previously grasp the water content of the soil to be improved and set the spraying amounts of the polymer aqueous solution for soil improvement and the aqueous soil improvement agent for cement. Specifically, using the soil to be improved, experimentally determine the amount of application of the polymer-based soil improvement agent aqueous solution and the cement-based soil improvement agent aqueous solution that can obtain the required improvement effect within the plastic limit.

As the cement-based earth and sand improving material of this example, a material containing a chelating material may be used. If an aqueous solution of cement containing no chelating agent is prepared and 1% or more of the weight of the cement is mixed and stirred, a chelate-containing cement-based soil improvement agent aqueous solution can be obtained.

As the chelating agent, for example, a finely powdered mineral was used as a base, and a high performance reducing agent was added to the base. According to this chelating agent, hexavalent chromium is reduced under alkaline conditions to precipitate it as a harmless trivalent chromium hydroxide compound, which is then precipitated (coprecipitated) with other suspensions and metal hydroxides. You can When the improving material of this example mixed with such a chelating material is used by mixing it with the earth and sand, hexavalent chromium does not elute from the improved earth and sand, and the damage to the environment is more decisive than post-examination measures. Very few,
Much more efficient.

An experiment was conducted to confirm what the mixing ratio of the cement and the chelating agent should be in the present improved material. Four types of improving materials were prepared in which the weight ratio of the chelating agent to cement 100 was set to four types of 0, 0.5, 1.0, and 1.5. Water 5 was added to each of the improved materials 1 in a weight ratio and well stirred, and a test for detecting hexavalent chromium was carried out on the resulting glaze water. The test method is to check the concentration (mg / l) of hexavalent chromium by aspirating well water into a case in which the reagent is enclosed and shaking it well, and comparing the color of water in the case after a predetermined time with the standard color. Is.

As a result, the amount of chelating agent was 0, 0.5,
For four types of 1.0 and 1.5, the detected hexavalent chromium concentration (mg / l) was 1 or more, 0.5 or more, respectively.
It was confirmed to be 0.1 or less and less than 0.05. Since the environmental standard is less than 0.05 mg / l, it is most desirable that the weight ratio of the chelating agent to cement 100 is 1.5 or more, but considering the error of the experiment, etc. It is considered that a considerable effect can be obtained for preventing chromium elution.

According to this example, the hexavalent chromium contained in the cement is not eluted into the environment by being sandwiched by the chelating material.

In each of the examples of the present invention described above, the aqueous solution of the polymer-based earth and sand improving material was sprayed on the earth and sand in the first step, but the powdery polymer-based earth and sand improving material was applied to the earth and sand in the first step. It is also possible to obtain the same effect as described above by spraying, mixing and stirring to mix with water contained in the earth and sand.
When the water content in the earth and sand is low, after spraying the powdery polymer-type earth and sand improving material on the earth and sand in the first step, sprinkling an appropriate amount of water and mixing and stirring to obtain a similar earth and sand improving effect. Obtainable.

[0041]

EFFECTS OF THE INVENTION According to the method for improving sand and sediment and the aqueous solution for improving polymer sediment of the present invention, the aqueous solution of improving sediment for polymer is sprayed on the sediment in the first step, or the soil for improving powder in powder form is used. Fine particles of earth and sand can be aggregated into a sand-like shape by spraying the improving material on the earth and sand, adjusting the water content of the earth and sand by water sprinkling, and mixing and stirring this. Further, in the second step, the aggregated earth and sand is wrapped with a powdery earth and sand improving material, whereby it is possible to obtain improved earth and sand which is not easily collapsed even when there is an external influence such as rainfall water.

In the second step, compost is sprayed on and mixed with the aggregated sand to increase voids by aggregating the cultivated soil, thereby providing various functions of air permeability, water retention and drainage. It is possible to raise the arable soil suitable for growing plantings.

Further, if a cement-based earth and sand improving material containing a chelate is used as the improving material added in the second step,
Sediment can be aggregated without seeing elution of hexavalent chromium.

Therefore, the earth and sand improved by the earth and sand improving method of the present invention having the above effects can also obtain the following substantial effects. 1. By providing a layer of aggregated sand with good drainage in the cultivated land, the runoff of rainwater can be adjusted and the problem of runoff of red water in Okinawa can be improved. 2. In the ground with poor drainage, it is possible to improve the environment of the ground surface by making the foundation ground good drainage. 3. A blind drainage ditch can be formed by forming a groove-like aggregated sediment layer on the foundation ground or bare land of cultivated land. It is impossible to restore the function of blind drainage with a conventional pipe when it loses its function due to clogging, but with this method, it is easy to restore the function of blind drainage by improving the sediment again.

4. Further, the present invention is useful for creating blind drainage ditch, improving wetland ground, manufacturing embankment material, and creating foundation ground for roads, grounds, park sites, and golf courses.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a facility for producing an aqueous solution of a polymer earth and sand improving material, which is an example of an embodiment of the present invention, and an implementation situation of a first step using the aqueous solution.

[Explanation of symbols]

10 ... Polymer-based soil improvement material 11 ... water 14a ... Aqueous solution of polymer-based soil improvement material 19 ... Unmodified soil

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Claims (8)

[Claims] 1. A method for improving sediment, which comprises spraying an aqueous solution of a polymer-based soil improver on the soil and mixing and stirring. 2. A method for improving sand and sand, which comprises spraying a powdery polymer-based sand and sand improving agent onto the sand and mixing and stirring. 3. The method for improving earth and sand according to claim 2, wherein water is sprinkled on the earth and sand. 4. A soil improvement method, which comprises spraying an aqueous solution of a polymer-based soil improvement agent on earth and sand, mixing and stirring the mixture, and then further dispersing a powdery lime-based earth and sand improving agent on the earth and sand, and mixing and stirring the mixture. Method. 5. The soil and sand improvement, which comprises spraying an aqueous solution of a polymer-based soil and sand improving agent on the soil and mixing and stirring the mixture, and then further spraying a powdery gypsum-based soil and sand improving agent on the soil and mixing and stirring the mixture. Method. 6. The soil and sand improvement, which comprises spraying an aqueous solution of a polymer-based earth and sand improving agent on the soil and mixing and stirring the mixture, and then further spraying a powdery cement-based soil and sand improving agent on the soil and mixing and stirring the mixture. Method. 7. A method for improving earth and sand, which comprises spraying an aqueous solution of a polymer-based earth and sand improving material on earth and sand, mixing and stirring the mixture, and then further spraying compost on the earth and sand and mixing and stirring. 8. An aqueous solution of a polymeric earth and sand improver, which is 0.5 or less with respect to 100 of water in a weight ratio.