JP3895822B2 - Purification method for contaminated ground - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for preventing the expansion of a contaminated area due to outflow of contaminated groundwater from a contaminated ground and purifying the contaminated area.
[0002]
[Prior art]
When constructing a structure such as a building on soft ground, in order to prevent long-term consolidation settlement and deformation of the ground due to the overload of such a structure, etc., and to prevent adverse effects on the surrounding ground For example, a sand pile is driven into the ground at regular intervals (sand compaction pile method). Moreover, the sand pile dissipates excess pore water pressure between the soil particles of the soft ground when a large earthquake occurs due to its good drainage function, so it is also effective as a means for preventing the liquefaction phenomenon of the ground. .
[0003]
In addition, since the soft ground is saturated with a large amount of groundwater, when a part of the ground is contaminated, the groundwater contaminated with the pollutant eluted from the contaminated ground flows into the surrounding ground. Contamination may spread. Therefore, in order to prevent such contamination from spreading, it is necessary to construct a water blocking wall that reaches the impermeable layer in the ground so as to surround the ground of the contaminated region, separately from the sand pile, or The required number of wells are excavated in the contaminated ground surrounded by the water blocking wall, the contaminated groundwater is pumped up and purified, and the purified water is condensed and permeated into the contaminated ground area to purify the contaminated ground. There is a need to.
[0004]
[Problems to be solved by the invention]
In the above prior art, the following problems are pointed out. In other words, when part or all of the soft ground is contaminated, in addition to the construction of many sand piles to increase ground strength and prevent liquefaction, the spread of pollution is prevented. It is necessary to construct a continuous water blocking wall to mine, or to excavate a well to pump up contaminated groundwater, resulting in prolonged construction and increased construction costs.
[0005]
The present invention has been made under the circumstances as described above, and the main technical problem thereof is soft ground treatment and diffusion of the contaminated area due to the outflow of contaminated groundwater from the contaminated area of the soft ground. It is to provide a construction method capable of preventing the above.
[0006]
[Means for Solving the Problems]
As a first means for effectively solving the technical problems described above, the method for purifying contaminated ground according to the present invention is based on permeable concrete mixed with carbonaceous adsorbent particles, typically activated carbon particles. The underground pillars are placed in the ground at predetermined intervals. Here, “water-permeable concrete” is composed of poor blended concrete (concrete with relatively little cement component), and has good water permeability due to the formation of fine continuous voids between the internal aggregates. Therefore, according to this construction method, it has a function of preventing long-term consolidation settlement and deformation of the ground, and a function of preventing excessive liquefaction of the ground by dissipating excess pore water pressure when a large earthquake occurs. In addition, the carbonaceous adsorbent mixed in the soil column has an excellent ability to adsorb pollutants dissolved in water. It is removed by adsorption and purified. The “carbonaceous adsorbent” refers to activated carbon particles or pulverized charcoal.
[0007]
[0008]
As a second means for effectively solving the conventional technical problems, the method for purifying contaminated ground according to the present invention is a method in which soil columns made of permeable concrete with charcoal as coarse aggregate are placed at predetermined intervals in the ground. It is something to be laid. Charcoal has excellent water permeability by itself having a porous structure. Adsorbing power to pollutants in water is lower than that of activated carbon, but the ratio of charcoal in soil columns is large by using as coarse aggregate, charcoal has a large specific surface area due to porous structure, vascular bundle, etc. Since a long water passage route is formed by carbonization of water, contaminants in the water can be satisfactorily adsorbed and removed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
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 is a soft ground contaminated in a landfill, etc. An impermeable layer made of viscous soil or rock under the soft ground 1, GWL is a groundwater level in the soft ground 1. In the soft ground 1, a substantially vertical underground column 3 having a lower end 3 a reaching the impermeable layer 2 is provided with a predetermined interval P in the horizontal direction.
[0010]
The soil pillar 3 in the present invention has a cross-sectional structure as shown in FIG .
[0011]
[0012]
Moreover, the underground pillar 3 shown to FIG. 2 (A) consists of the concrete pile 3B which mixed and poured the permeable concrete 33 and the activated carbon 32. FIG. The water-permeable concrete 33 is a poorly-mixed concrete in which the mixing ratio of the cement component is relatively low, and countless fine continuous voids (not shown) are obtained by using a sand having a relatively large particle size as an aggregate. ) Is formed, and this provides good water permeability. For this reason, the contaminated groundwater is purified by adsorbing and removing the contaminants by contacting the activated carbon 32 in the process of flowing through the continuous voids between the aggregate particles of the permeable concrete 33.
[0013]
In the construction of this concrete pile 3B (soil column 3), first, a hole 1a is formed in the contaminated soft ground 1, and then an uncured permeable concrete in which activated carbon 32 is mixed into the hole 1a. It is placed by injecting 33.
[0014]
Depending on the placement interval P and diameter D of the soil pillars 3 and the contamination status of the soft ground 1, for example, particles obtained by pulverizing charcoal may be mixed instead of the activated carbon 32, and such a carbonaceous adsorption is also possible. The mixing ratio of the materials is also appropriately determined according to the placement interval P, the diameter D, the contamination status of the soft ground 1 and the like.
[0015]
Moreover, the underground pillar 3 shown to FIG. 2 (B) consists of the concrete pile 3C which laid the water-permeable concrete 33 by using the charcoal 34 as a coarse aggregate. As described above, the charcoal 34 has a good water permeability because it has innumerable long water passages formed by carbonization of vascular bundles and the like, and each charcoal 34 is used as a coarse aggregate. Since the charcoal 34 are in contact with each other, the groundwater that has entered the charcoal 34 directly through the continuous voids of the permeable concrete 33 is adsorbed and removed in the process of flowing through the long water passage of the charcoal 34. To be purified.
[0016]
In the construction of this concrete pile 3C (submerged pillar 3), first, a hole 1a is formed in the contaminated soft ground 1, and then charcoal 34 crushed to an appropriate size is put into this hole 1a. After that, the uncured water-permeable concrete 33 is poured and poured. The uncured permeable concrete 33 thus injected is filled and hardened so as to fill the gap between the charcoal 34.
[0017]
FIG. 3 shows the case where the underground pillar 3 is laid from the position of the rhombus lattice point on the ground surface, and the groundwater generally flows in the ground from the left side to the right side of FIG. It shall be. As is clear from this figure, the groundwater is given the opportunity to pass through the underground pillar 3 many times in the process of flowing through the ground, so this groundwater is purified as it flows to the right, and contaminated groundwater Diffusion of contaminated areas due to spills is prevented.
[0018]
【The invention's effect】
According to the purification method for contaminated ground according to the present invention, activated carbon or charcoal is blended into the soil column to prevent long-term consolidation settlement and deformation of soft ground or to prevent liquefaction of the ground when a large earthquake occurs. As a result, the contaminated groundwater is purified in the process of being drained through the soil column, thus preventing the spread of pollution. Construction of the closed water barrier and pumping up contaminated groundwater is unnecessary, and construction can be shortened and construction costs can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic vertical sectional view of a preferred embodiment of a contaminated ground purification method 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 the relationship between the arrangement of soil columns and the groundwater flow in the embodiment.
[Explanation of symbols]
1 Soft ground 2 Impervious layer
3 pillars
32 Activated carbon (carbonaceous adsorbent)
33 Permeable concrete 34 Charcoal

Claims (3)

A method for purifying contaminated ground, characterized in that soil columns made of permeable concrete mixed with particles of carbonaceous adsorbent are placed in the ground at predetermined intervals. In the construction method according to claim 1,
A purification method for contaminated ground, characterized in that the carbonaceous adsorbent is activated carbon.   A method for purifying contaminated ground, characterized by placing underground columns made of permeable concrete made of charcoal coarse aggregate into the ground at predetermined intervals.

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