JP3311733B2 - Contaminated soil containment treatment method and foundation structure construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a technique for contaminating contaminated soil underground.

[0002]

2. Description of the Related Art Various methods have been provided to date for treating soil contaminated with harmful substances (heavy metals, organochlorine compounds, etc.) that have an adverse effect on the human body and the environment. In the following, the main processing methods are listed, and their problems are described.

(Washing and classification treatment) Contaminated soil is washed with a washing liquid comprising water, a surfactant and the like, and classified into turbid water containing contaminants and soil. In this method, the target soil is limited to a soil containing a large amount of reki and sand. In addition, a large amount of turbid water containing contaminants and high water-containing fine-grained soil (mud soil) are generated, and the treatment costs are high.

(Heating / melting treatment) Large energy and equipment are required, and the amount of treatment per hour is small. For volatile substances, substances such as cadmium, arsenic, lead, and the like, which are harmful to the elements themselves, the treatment of exhaust gas requires a large cost.

(Pumping treatment / gas suction treatment) A long treatment period is required. In addition, it is difficult to grasp the groundwater flow and geological properties, and there is a problem in the reliability of the effect.

(Biological treatment) This is a detoxification treatment using pollutant-decomposing bacteria, but requires a long treatment period. In addition, the number of effective bacteria (bacteria) that have been confirmed is limited, and it cannot be said that the technology has been completed.

(Other treatments) Various treatment techniques such as electrolysis and oxidation-reduction decomposition methods have been proposed, but those which meet social needs, such as low processing capacity per hour and high cost. is not. Further, there are substances, such as PCBs, which are prohibited from carrying out pollutants to places other than the polluted place and are obliged to treat them in situ.

Thus, these treatment methods do not always satisfy social needs. Therefore, at present, the "solidification / containment treatment", in which contaminated soil is solidified and insolubilized with a solidifying material such as cement or lime and discarded and treated in a place (disposal site) surrounded by concrete or a water-impermeable sheet, Is generally adopted as a method that can be processed in the largest quantity at low cost.

[0009]

[Problems to be Solved by the Invention] However, it is very difficult to secure a place for disposal (disposal site) in consideration of the risk of leakage and diffusion of contaminants from narrow land areas and disposal sites in Japan. It is in. In addition, soil that still contains contaminants even after insolubilization is not allowed to be reused without limitation as a soil material. On the other hand, there have been proposed methods of installing a large concrete tank below the contaminated site, or installing an underground disposal site using underground continuous walls or sheet piles. Or to block the surrounding area.

[0010] Therefore, a main object of the present invention is to make it easy to secure a containment place and to reduce construction costs. Another problem is to treat the contaminated soil without removing it from its location, to make it difficult to affect the surroundings such as blocking groundwater flow, and to make the place where the contaminated soil was present after treatment non-existent. The purpose is to make effective use as contaminated soil or land.

[0011]

According to the present invention which has solved the above-mentioned problems, according to the first aspect of the present invention, a containment hole is excavated in a target ground, and contaminated soil is placed in a container means in the excavation hole. A method of containing contaminated soil, characterized by filling and solidifying a filled solidification material so as to surround at least the periphery of the arranged container means and sealing the contaminated soil underground. is there.

[0012] According to a second aspect of the present invention, by drilling a casing using a casing tube, a containment hole reaching a bedrock layer is drilled, and after the drilling, the casing tube is inserted into the drilling hole. The contaminated soil is placed in the container means, and then the solidification material is filled and solidified so as to surround at least the disposed container means while pulling out the casing tube, thereby confining the contaminated soil in the ground. A method for containing contaminated soil.

According to a third aspect of the present invention, after the container means is disposed in the drilling hole in an empty state, the contaminated soil supply pipe is positioned through the drilling hole with its tip outlet located in the container means. 3. The method according to claim 1, wherein the contaminated soil is supplied into the container means through the contaminated soil supply pipe in a state where the contaminated soil is supplied.

According to a fourth aspect of the present invention, the solidified material filling pipe is drawn through the solidified material filling pipe while pulling out the solidified material filling pipe after positioning the leading end outlet of the solidified material filling pipe at the bottom of the drilled hole. The method for containing contaminated soil according to claim 1, wherein filling is performed.

According to a fifth aspect of the present invention, the container means comprises a cylindrical body having a bottom lid formed of metal, resin, cloth, or cloth with a reinforcing net attached thereto. A method for containing contaminated soil according to any one of the preceding claims.

According to a sixth aspect of the present invention, there is provided the method for contaminating contaminated soil according to any one of claims 1 to 5, wherein the contaminated soil is solidified at least prior to filling the solidified material. is there.

According to a seventh aspect of the present invention, there is provided a method according to any one of the first to sixth aspects, wherein a bacterium that decomposes pollutants is mixed into the contaminated soil at least prior to the filling of the solidification material. This is a method for soil containment.

The invention according to claim 8 is characterized in that, as the filled solidified material, one having a water permeability lower than the order of 10 ^-5 cm / sec after solidification is used. This is a method for containing contaminated soil.

According to a ninth aspect of the present invention, there is provided a method for confining a surface contaminated soil in a land where contaminants are unevenly distributed on a surface layer of the ground without carrying the contaminated soil out of the land. 9. Containing contaminated soil according to any one of claims 1 to 8, wherein the contaminated soil is taken out by excavation and contained in the ground of the land by the containment processing, and the surface excavation site is backfilled with non-contaminated soil. Processing method.

According to a tenth aspect of the present invention, a containment hole is excavated in a target ground, and contaminated soil is placed in the excavation hole in a state where the contaminated soil is placed in the container means. A solidification material is filled and solidified so as to surround the soil, thereby forming a substructure in which the contaminated soil is sealed in the underground portion.

<Actions> As described above, the present invention can reliably contain contaminated soil deep underground, so that the outflow and scattering of contaminants into groundwater, evaporation and diffusion into the atmosphere, and the like are reliably prevented. Is done. And by such underground containment, it is not necessary to secure a disposal site widely on the ground unlike the related art, and since the above-ground part can be effectively used after the treatment, the disposal site can be easily secured. Therefore, there is an advantage that the construction cost can be reduced as compared with the case where a special disposal place is formed.

On the other hand, as is well known, the thickness of soil contaminated with contaminants is generally within about 5 m (often about 3 m) from the ground surface. Therefore, in particular, the surface contaminated soil is removed by excavation as described in claim 9 and is confined in the ground in the land by a confinement process, and the surface excavation site is backfilled with non-contaminated soil, thereby obtaining the surface layer of the ground. In a land where pollutants are unevenly distributed, the surface contaminated soil can be contained without being carried out of the land, and the above-ground portion can be reused.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments of the present invention will be described below in detail with reference to an example of in-land containment processing on land where pollutants are unevenly distributed on the surface layer of the ground. <Surface excavation step> As described above, the thickness of soil contaminated with contaminants is about 5 m or less from the surface of the ground (often about 3 m or less, sometimes 10 to 20 m). Therefore, first, as shown in FIG. 1, the surface contaminated soil 2 is taken out by excavation and is temporarily piled up on the treated or untreated place in the land 1, and the surface excavation site is made of non-contaminated soil or the like. Backfill with good quality soil material (may be brought from outside the land) 3.

Note that this backfilling can be the final step. Further, when the place where the contaminated soil is contained is not the basement of the place where the contaminated soil is present as in the present embodiment but is contained under the non-contaminated ground, the surface excavation step can be omitted.

<Containment Hole Excavation Step> Next, as shown in FIG. 2, a confinement hole H extending from the ground to the ground is excavated in the non-contaminated soil backfilling site (or surface excavation site) 3 by the excavator 4, 5 or the like. . The excavated soil (remaining soil) 6 in this excavation can be effectively used as general soil material as construction generated soil (high quality soil).

In the present invention, the depth of the hole H is not particularly limited. However, after the treatment, it is preferable to secure a sufficient earth covering for the containment part so as not to hinder land use on the above-ground part (surface part) on the containment part and not to block the groundwater flow. Further, in order to enable disposal of a large amount of contaminated soil, it is preferable that the containment hole H be as deep as possible. Therefore, in the present invention, it is desirable to excavate the containment hole H so as to reach from the ground to the inside of the bedrock layer.

For effective utilization after the discharged soil (remaining soil) 6, it is desirable to adopt an excavation method that does not disturb the discharged soil 6 as much as possible. As such a drilling means, a general cast-in-place pile excavator such as a reverse circulation method may be used, but an all-casing excavator that can perform glove excavation while preventing the collapse of a hole wall deep underground during operation and suppressing the influence of groundwater. It is desirable to use a construction method (such as a Benoto construction method, an MRO construction method, or a multi-drill construction method), that is, a method of sequentially inserting the casing pipe 4C into the hole H together with the drilling by the hammer grab 5G as shown in the figure.

<Contaminated soil arranging step> When the excavation to the predetermined depth is completed, the contaminated soil is arranged in the excavation hole H in a state of being placed in the container means 7. For this reason, in this example, as shown in FIGS. 3 and 4, with the casing pipe 4C inserted into the excavation hole H, the empty container means 7 is first put into the casing pipe 4C by the hanging device 8 such as a crane. After being placed at the bottom of the hanging hole, a contaminated soil supply pipe 9 such as a tremie pipe is inserted into the casing pipe 4C from the base end opening of the casing 4C (from the hole opening to the hole when the casing is not used) and inserted into the casing pipe 4C. With the outlet located in the container means 7, the contaminated soil 2 is supplied and filled into the container means 7 by gravity or by pumping through the contaminated soil supply pipe 9.

As the container means 7, metal, resin, cloth,
Or reinforcement net (Geonet or other sheet for civil engineering)
It is preferable to use a tubular body having a bottom lid and formed of a cloth to which is adhered, but a container or a bag body of another shape may be used. In the case of the container means 7 having an opening only on the upper surface as shown in the illustrated example, it is preferable that the contaminated soil is filled into the container means 7 while the tip of the supply pipe 9 is pulled toward the mouth from the bottom of the container means 7. In the present invention, a closed container or the like can also be used. In this case, the contaminated soil is put in a container and sealed in advance on the ground, and placed in the hole.

The contaminated soil 2 is solidified and insolubilized by adding a solidifying material at least prior to the subsequent filling step of the solidifying material, preferably prior to filling in the container means, or decomposing the contaminants. It is preferable to mix bacteria that cause the degradation. Specifically, as shown in FIG. 4, in a mixing plant 10 installed near the processing unit, after mixing the contaminated soil 2 piled and stored on the ground with the solidifying material or bacteria, an input device 11 such as a flight conveyor is used.
Into the hopper 9H attached to the supply pipe 9 base end opening,
We propose a method to put contaminated soil that has been mixed and processed in sequence.
As the solidifying material used for the insolubilization, known cement, lime, or a polymer-based solidifying material can be used.

<Filling Step of Filled Solidified Material> Then, the filled solidified material is filled and solidified so as to surround at least the periphery of the container means 7 disposed in the containment hole H, preferably to or near the hole. , Contain contaminated soil underground.

That is, in the case of this example, as shown in FIG. 5, the solidified material filling pipe projects through the casing pipe 4C from the tip thereof, and the opening of the tip faces between the outer surface of the container means 7 and the inner surface of the hole H. 12 is attached to the casing tube 4C, and while the casing tube 4C inserted and held in the hole H is pulled out while rotating, the filled solidified material M from the solidified material supply plant 13 is located closer to the hole bottom than the front end of the casing tube 4C. Is filled into the hole H via the filling tube 12 facing the hole. Thereby, the casing tube 4C is pulled out and the casing tube 4C is pulled out.
Filled solidified material M is sequentially filled in the space in the hole ahead of the C tip, and contaminated soil is sealed in the ground while being wrapped by the filled solidified material. This filled solidified material M is
As shown in FIG. 6, which will be described later, the filler is filled up to the vicinity of the hole. However, only the portion surrounding the periphery of the container means 7 is filled with the filler solidified material M, and above this, a high quality soil such as non-contaminated soil is placed. Material can also be filled (not shown).

When the casing tube is not used, the solidified material filling pipe may be exposed while the solidified material filling tube faces the bottom of the hole, that is, between the outer surface of the container means and the inner surface of the hole, and then the solidified material is filled while pulling up the tube. Zu).

The solidification material M to be used includes fluidity,
The material is not limited to one processed by a specific method as long as it has self-hardening property and watertightness, and cement, lime, a polymer-based solidifying material, or the like can be used. In particular, it is preferable to use one having a water permeability lower than the order of 10 ^-5 cm / sec after solidification. Further, a contaminant permeation prevention material such as a known contaminant supplement material can be added to the solidified material.

<Completion of Construction> Thus, as shown in FIG. 6, the contaminated soil 2 put in the container means 7 is sealed inside the pile made of the solidified solid material M created in the ground.
In FIG. 6, the sealing hole portion of the surface layer backfilling portion 3 is backfilled with non-contaminated soil or the like again after the solidification material M is filled. In addition, when the amount of contaminated soil is large and one or one containment hole is not enough, other parts in the treatment area can be similarly contained and can be dealt with by underground containment at a plurality of places. .

After the completion of the containment, the contaminated soil is locally and reliably contained in the ground, and since there is no contaminated soil on the ground, there is almost no influence on the surrounding environment, Effective use of land 1 can be achieved as in contaminated land.

<Application Example: Underground Substructure> As described above, one of the points of the present invention is the effective use of the above-ground portion corresponding to the containment site, and it is simply a land, that is, a park or a waste disposal site. Although it can be reused as such, it is also proposed to effectively use the contained material as a substructure. Specifically, as shown in FIG. 7, by applying the containment method of the present invention, the foundation piles 22, 22... , And can be used as the foundation of the building 20. In FIG.
Reference numeral 21 denotes a basement.

<Others: Containment Depth> In the present invention, assuming that the land containing the contaminated soil is to be effectively used, the land is assumed to be used below the depth assumed for use in the land use form, for example, the third basement floor. When building a building below the depth of about 3 basement floors (about 10m),
It is preferable to perform the construction so that at least the upper end of the contained contaminated soil is located (the depth of the containing hole and the height of the container means are set). As a result, the land containing the contaminated soil can be effectively used without any trouble.

[0039]

As described above, according to the present invention, soil contaminated with contaminants is confined deeply into the ground without being carried out from its location, and is discharged into groundwater, dust is scattered, Evaporation and diffusion into the atmosphere can be prevented, and the land above the ground can be effectively used.
Therefore, it is easy to secure a disposal site for the contaminated soil.
Furthermore, existing equipment such as a drilling machine and a plant for filling the solidified material can be used, and the construction target area can be narrow, so that construction can be performed at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic view of a surface excavation step according to the present invention.

FIG. 2 is a schematic view of a process of excavating a containment hole according to the present invention.

FIG. 3 is a schematic diagram of a contaminated soil arranging step according to the present invention.

FIG. 4 is a schematic view of a contaminated soil arranging step according to the present invention.

FIG. 5 is a schematic view of a filling step of a filled solidification material according to the present invention.

FIG. 6 is a schematic diagram of a construction completion state according to the present invention.

FIG. 7 is a schematic diagram of an underground substructure according to the present invention.

[Explanation of symbols]

1 ... land, 2 ... contaminated soil, 3 ... good-quality soil material, 4, 5 ...
Excavator, 4C: casing tube, 5G: hammer grab,
6: Excavation, 7: Container means, 8: Hanging device, 9
... Contaminated soil supply or 10 ... Mixing plant, 11 ... Flight conveyor, 12 ... Filling tube, 20 ... Building, 21 ... Basement, 22 ... Contaminated soil inclusion foundation pile, 23 ... Normal foundation pile, H
… Containment hole, M… Filled solidified material.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B09B 1/00-5/00

Claims (10)

(57) [Claims] 1. A containment hole is excavated in a target ground, and contaminated soil is placed in the excavation hole in a state of being placed in a container means, and is filled and solidified so as to surround at least the periphery of the arranged container means. A method for containing and contaminating contaminated soil, which comprises filling and solidifying the material to contain the contaminated soil in the ground. 2. Excavation of a containment hole reaching a bedrock layer by casing excavation using a casing tube, and after excavation, inserting a casing tube into the excavation hole.
The contaminated soil is placed in the casing means in the casing tube, and then the filling solid is filled and solidified so as to surround at least the periphery of the arranged container means while pulling out the casing tube, thereby solidifying the contaminated soil. A method for containing contaminated soil, characterized by being contained in the ground. 3. After the container means is placed in the drilling hole in an empty state, the contaminated soil supply pipe is conveyed through the drilling hole with its tip outlet positioned in the container means. 3. The method according to claim 1, wherein the contaminated soil is supplied into the container means through a soil supply pipe. 4. The method according to claim 1, further comprising, after positioning the leading end outlet of the solidified material filling pipe at the bottom of the drilling hole, filling the solidified material into the drilled hole via the solidified material filling pipe while pulling out the solidified material filling pipe. The method for containing contaminated soil according to any one of claims 1 to 3. 5. The container means may be a metal, a resin, a cloth,
5. The method for containing contaminated soil according to claim 1, wherein a tubular body having a bottom cover and formed of a cloth to which a reinforcing net is attached is used. 6. 6. The method for contaminating contaminated soil according to claim 1, wherein the contaminated soil is solidified at least prior to filling the solidified material. 7. The method for contaminating contaminated soil according to claim 1, wherein bacteria contaminating a contaminant are mixed into said contaminated soil at least prior to filling of said solidification material. 8. The method for contaminating contaminated soil according to claim 1, wherein a material having a water permeability lower than the order of 10 ⁻⁵ cm / sec after solidification is used as said filled solidified material. . 9. A method for confining a surface contaminated soil to a surface where contaminants are unevenly distributed on the surface of the ground without removing the surface contaminated soil from the land. 9. The method for containing contaminated soil according to any one of claims 1 to 8, wherein the contaminated soil is confined in the ground of the land by the containment processing, and a surface excavation site is backfilled with non-contaminated soil. 10. A containment hole is excavated in a target ground, contaminated soil is placed in the excavation hole in a state of being placed in a container means, and a solidifying material is formed so as to surround at least the periphery of the arranged container means. Filling and solidifying to create a substructure that contains contaminated soil in the underground.