JPH10245861A - Method of purifying contaminated ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent scattering of a contaminated area by outflow of contaminated underground water from the contaminated area of a soft and weak ground by placing a underground column composed of a sand pile mixing the particles of coal adsorption material, typically those of activated carbon at prescribed intervals. SOLUTION: While a soft and weak ground 1 is vertically excavated by a ground boring machine such as, for instance, a screw auger in the soft and weak ground 1 contaminated by a reclamation ground and the like, a casing pipe is inserted so that a hole inside wall does not collapse and a cylindrical excavation hole 1a reaching an impermeable layer 2 is formed. Next, while the casing pipe is pulled, a mixture of sand and activated carbon is placed in the excavation hole 1a to form an underground column 3. Next, when it is supposed that underground water generally flows from the left side to the right side, chances in which underground water passes through the underground column 3 in a process in which underground water flows in the ground many times are given, as underground water flows to the right, it is cleaned, and scattering of the contaminated area by outflow of contaminated underground water can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention is to prevent the expansion of a contaminated area due to the outflow of contaminated groundwater from contaminated ground,
The present invention relates to a technique for purifying a contaminated area.

[0002]

2. Description of the Related Art When constructing a structure such as a building on soft ground, long-term consolidation settlement or deformation of the ground due to the overload of such a structure or the like is prevented, and adverse effects on the surrounding ground are prevented. In order to prevent this, sand piles are driven into the ground at regular intervals (sand compaction pile method). Moreover, the sand pile disperses excessive pore water pressure between the soil particles of the soft ground at the time of the occurrence of a large earthquake due to its good drainage function, and is therefore effective as a means for preventing the liquefaction phenomenon of the ground. .

[0003] Further, since the soft ground is saturated with a large amount of groundwater, when a part of the ground is contaminated, the groundwater contaminated with contaminants eluted from the contaminated ground is removed from the surrounding ground. Spills may spread the contamination. Therefore, in order to prevent the spread of such contamination, it is necessary to construct a water blocking wall that reaches the impermeable layer in the ground, separately from the sand pile, so as to surround the ground in the contaminated area, or The required number of wells are drilled in the contaminated ground surrounded by the water stoppage wall, the contaminated groundwater is pumped and purified by pumping, and the purified water is condensed into the contaminated ground area to be purified, thereby purifying the contaminated ground. There is a need to.

[0004]

The following problems are pointed out in the above prior art. In other words, when part or all of the soft ground is contaminated,
In addition to installing many sand piles to increase the ground strength and prevent liquefaction, construct continuous water barriers to prevent the spread of pollution, and drill wells to contaminate groundwater. Construction work is required, which leads to prolonged construction and increased construction costs.

The present invention has been made under the above circumstances, and its main technical subjects are soft ground treatment and pollution caused by outflow of contaminated groundwater from a contaminated area of the soft ground. It is an object of the present invention to provide a construction method capable of preventing diffusion of a region.

[0006]

Means for Solving the Problems As a first means for effectively solving the above-mentioned technical problems, a method for purifying contaminated ground according to the present invention is a method for purifying particles of carbonaceous adsorbent, typically activated carbon. An underground pillar made of a sand pile mixed with particles is cast at predetermined intervals in the ground. According to this method, soil pillars made of sand piles have good water permeability, so that they can prevent long-term consolidation settlement and deformation of the ground as well as ordinary sand piles. It has the function of dissipating pore water pressure and preventing liquefaction of the ground. In addition, since the carbonaceous adsorbent mixed with the soil pillar has excellent adsorption capacity for pollutants dissolved in water, the polluted groundwater is contaminated during the process of being drained through the soil pillar. It is removed by adsorption and purified.

[0007] As a second means for effectively solving the conventional technical problems, a method for purifying contaminated ground according to the present invention is a method for purifying contaminated soil, which is characterized in that a particle of a carbonaceous adsorbent, typically a particle of activated carbon, is mixed with a permeable material. An underground pillar made of a reinforced concrete is cast at predetermined intervals in the ground. Here, the “water-permeable concrete” is made of poorly-mixed concrete (concrete having a relatively small amount of cement component) and has good water permeability due to the formation of fine continuous voids between the internal aggregates. Since the carbonaceous adsorbent has an excellent ability to adsorb contaminants in water, it has the same effect as described above. The “carbonaceous adsorbent” refers to activated carbon particles or charcoal ground.

[0008] As a third means for effectively solving the conventional technical problem, the method for purifying contaminated ground according to the present invention is based on an underground column made of permeable concrete using charcoal as coarse aggregate. At predetermined intervals. Charcoal is
By having a porous structure, it itself has excellent water permeability. Adsorbing power for pollutants in water is lower than activated carbon, but by using it as coarse aggregate, the ratio of charcoal in soil pillars is large, and charcoal has a large specific surface area due to its porous structure, vascular bundles, etc. As a result, a long water passage is formed by carbonization, so that contaminants in water can be adsorbed and removed well.

[0009]

1 to 3 schematically show a preferred embodiment of a method for purifying contaminated ground according to the present invention. First, in FIG. 1, reference numeral 1 denotes a polluted landfill or the like. The soft ground 2 thus obtained is an impermeable layer made of viscous soil or rock below the soft ground 1, and GWL is a groundwater level in the soft ground 1. On the soft ground 1, substantially vertical earth pillars 3 whose lower ends 3a reach the inside of the water-impermeable layer 2 are cast at a predetermined interval P in the horizontal direction.

The earth pillar 3 in the present invention is shown in FIGS.
It has a cross-sectional structure as shown in FIG. First, the soil pillar 3 shown in (A) is a sand pile 3A in which sand 31 and activated carbon 32 are mixed.
It consists of Since the sand pile 3A has good water permeability due to the myriad of continuous voids formed between the particles of the sand 31, the contaminated groundwater that has entered the sand pile 3A flows through the continuous void between the particles of the sand 31. By contacting the activated carbon 32, contaminants are adsorbed and removed and purified.

In the construction of the sand pile 3A (the underground pillar 3), first, while excavating the soft ground 1 in a vertical direction with a ground drill such as a screw auger, a casing pipe is formed so that the inner wall of the hole does not collapse. By inserting
A cylindrical hole 1a reaching the impermeable layer 2 is formed. Then, while pulling out the casing pipe, a mixture of sand 31 and activated carbon 32 is poured into the hole 1a.

The underground pillar 3 shown in FIG. 2 (B) is composed of a concrete pile 3B which is formed by mixing activated carbon 32 into permeable concrete 33 and placing the same. The permeable concrete 33 is a poorly-mixed concrete in which the mixing ratio of the cement component is relatively small. By using a sand having a relatively large particle size as the aggregate, it is possible to countless fine continuous voids (not shown). ) Has a formed tissue, thereby giving good water permeability. For this reason, similarly to the case of the above-mentioned sand pile 3A, in the process of flowing the contaminated groundwater through the continuous voids between the aggregate particles of the permeable concrete 33, the contaminant is adsorbed and removed by the contact with the activated carbon 32 and purified. You.

In the construction of the concrete pile 3B (the underground pillar 3), first, as in the case of the above-mentioned sand pile 3A, the drilled hole 1a is formed in the contaminated soft ground 1, and then this is formed. The unhardened permeable concrete 33 mixed with the activated carbon 32 is poured into the drilled hole 1a.

Depending on the spacing P and diameter D of the underground pillars 3 and the state of contamination of the soft ground 1, for example, particles obtained by pulverizing charcoal may be mixed in place of the activated carbon 32. The mixing ratio of the carbonaceous adsorbent is appropriately determined according to the casting interval P, the diameter D, the state of contamination of the soft ground 1, and the like.

The soil column 3 shown in FIG. 2 (C) is made of a concrete pile 3C in which permeable concrete 33 is cast using charcoal 34 as a coarse aggregate. As described above, the charcoal 34 itself has good water permeability because an infinite number of long water passages are formed by carbonization of vascular bundles and the like, and by using it as a coarse aggregate, Since the charcoals 34 are in contact with each other, contaminants are adsorbed and removed in the course of flowing through the long water passage of the charcoal in the groundwater that has entered the charcoal 34 through the continuous voids of the permeable concrete 33 or directly. , Be purified.

In the construction of the concrete pile 3C (the underground pillar 3), as in the case of the sand pile 3A described above,
First, a drilled hole 1a is formed in the contaminated soft ground 1, and then a charcoal 34 crushed to an appropriate size is put into the drilled hole 1a, and then unhardened permeable concrete 33 is injected. Cast in. The poured uncured permeable concrete 33 is filled so as to fill the gap between the charcoals 34 and hardens.

FIG. 3 shows a case where the underground pillar 3 is driven from the position of the rhombic lattice point on the ground surface. As shown by a large number of arrows, the groundwater generally passes through the ground from left to right in FIG. It is assumed that it is flowing to As is clear from this figure, the groundwater will be given the opportunity to pass through the earth pillar 3 many times in the course of flowing through the ground, and therefore this groundwater will be purified as it flows to the right, The diffusion of the contaminated area due to the outflow of water is prevented.

[0018]

According to the method for purifying contaminated ground according to the present invention, an underground pillar for preventing long-term consolidation settlement and deformation of soft ground or preventing liquefaction of the ground when a large earthquake occurs, The incorporation of activated carbon or charcoal provides excellent adsorption capacity for contaminants dissolved in water, so that contaminated groundwater is purified as it is drained through soil pillars, thus reducing the spread of pollution. There is no need to construct a continuous water stop wall to prevent this, or to pump up contaminated groundwater, thus shortening the construction and reducing construction costs.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a preferred embodiment of a method for purifying contaminated ground according to the present invention.

FIG. 2 is an explanatory view schematically showing an internal structure of a soil column in the embodiment.

FIG. 3 is an explanatory diagram schematically showing a relationship between an arrangement of underground pillars and a groundwater flow in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Soft ground 2 Impervious layer 3 Soil column 31 Sand 32 Activated carbon (carbonaceous adsorbent) 33 Permeable concrete 34 Charcoal

Claims (4)

[Claims] 1. A method for purifying a contaminated ground, wherein a soil column composed of a sand pile mixed with particles of a carbonaceous adsorbent is cast at predetermined intervals in the ground. 2. A method for purifying contaminated ground, wherein soil columns made of permeable concrete mixed with particles of a carbonaceous adsorbent are cast at predetermined intervals in the ground. 3. The method for purifying contaminated ground according to claim 1, wherein the carbonaceous adsorbent is activated carbon. 4. A method for purifying contaminated ground, comprising placing soil columns made of permeable concrete using charcoal as coarse aggregate at predetermined intervals in the ground.