JP5441192B2 - Contaminated soil purification method - Google Patents

Description

  The present invention relates to a technique for purifying soil contaminated with, for example, a volatile organic compound (VOC). More specifically, the present invention relates to a contaminated soil purification technique that can be suitably implemented even when soil in a deep region is contaminated.

In FIG. 14, the pollutant leaks due to the damage of the tank (not shown) of the factory 2, and the pollutant penetrates deep into the soil G.
Since the contaminant moves downward between the soil particles by the action of gravity, the soil contaminated region Gp does not spread so much in the left-right direction in FIG. 14 and penetrates downward in FIG. Therefore, the contaminated area Gp reaches a deep underground area.
In FIG. 14, the area contaminated by the pollutant is indicated by the reference sign Gp, the reference sign 30f indicates the ground surface, the reference sign Ep indicates the area where the pollutant purification process is to be performed, and the reference sign Epb is the deepest of the area Ep. Shows the part.

As shown in FIG. 14, in order to remove the contaminated soil in the contaminated region Gp, it is necessary to excavate to a deep underground region, but excavation to a deep underground region is difficult by human power. Often, large machines (so-called “heavy machinery”) should be used.
However, when the contaminated area Gp is in the vicinity of a private house, there is a situation where it is desired to refrain from using heavy machinery as much as possible from the viewpoint of noise and safety.
That is, in order to purify the contaminated soil Gp as shown in FIG. 14, it is necessary to satisfy both the demand for excavating deep underground and the demand for refraining from using heavy machinery. In other words, it is necessary to satisfy conflicting requests at the same time.

As a technique for satisfying such a request, a technique as shown in FIG. 15 can be considered.
In FIG. 15, the range including the contaminated area Gp is excavated to a predetermined depth, the liner ring 2 is installed in the excavated area, and the shaft 40 is drilled in the area including the contaminated area Gp. To do. A plurality of ring-shaped metal frames (liner rings) 2 are installed on the wall surface of the drilled shaft 40.
The contaminated soil present in the contaminated area Gp is moved to the ground side when excavating the shaft 40, and the contaminant is removed at a contaminated soil treatment facility (not shown), or a transport means (not shown) such as a transport vehicle. Is moved from the shaft 40 to a contaminated soil treatment facility (not shown) provided at a remote point.

If the shaft 40 is excavated to the deepest part Epb of the contaminated area Gp and the liner ring 2 is installed, the pollutant such as VOC is measured in the space inside the area in the radial direction of the area where the liner ring 2 is installed. Verify that the material has been removed.
Then, the liner ring 2 is removed in order from the liner ring 2 arranged at the deepest position, and the work of refilling the area from which the liner ring 2 has been removed with high quality soil is repeated. If the liner ring 2 is removed to the ground surface and the backfilling is completed, the purification of the contaminated soil is completed.
If the purification technique as shown in FIG. 15 is used, when the contaminated soil is excavated and sent to the ground side for processing, the portion where the liner ring 2 is installed does not collapse, so only the region surrounded by the liner ring 2 is used. Can be excavated. Therefore, when excavating the vertical shaft 40, it is possible to excavate deeper into the ground than by the small excavating machine 1 (for example, a self-propelled small backhoe) or by hand. And it does not require the use of heavy machinery.

However, the purification technique shown in FIG. 15 is difficult to apply when the pollutant reaches a region below the groundwater level.
When the contaminated area Gp reaches an area deeper than the groundwater level, an area deeper than the groundwater level must be excavated, but in an area deeper than the groundwater level (area below the groundwater level) Spring is generated during excavation. Even in the region surrounded by the liner ring 2, water springs out during excavation.
Even in the region surrounded by the liner ring 2, the region below the groundwater level cannot be excavated due to spring water, so the construction method shown in FIG. It cannot be purified.

As another conventional technique, for example, there is a technique of embedding a freezing pipe around an excavation target area and freezing the circumference of the excavation target area to drill a drilling hole (see Patent Document 1).
However, as described above, the pollutant diffuses in the direction in which gravity acts, so that the contaminated area often extends to a deep underground area. In such a case, it is difficult to apply the related art (Patent Document 1) because a large cost is required to freeze the entire periphery of the excavation target area.
Patent Document 1 is a technology related to the removal of unnecessary reserves derived from nature buried in the ground and artificial deposits such as weapons discarded in the past, and is not intended to purify contaminated soil. Absent.

JP 2006-263557 A

  The present invention has been proposed in view of the above-described problems of the prior art, and it is possible to purify contaminated soil existing below the groundwater level, and does not require the use of heavy machinery for excavation. The purpose is to provide a method for cleanup of contaminated soil.

According to the present invention, in the contaminated soil purification method for purifying contaminated soil existing below the groundwater level (Lw), the bottom (Gcb) is below the groundwater level (Lw) below the contaminated area (Gp). ) Is solidified, and the side surface (Gcs) is solidified between the peripheral edge of the bottom (Gcb) and the groundwater level (Lw), and the contaminated region (Gp) below the groundwater level (Lw) is (Gcb) and the side surface part (Gcs) are surrounded by the excavated shaft (40) in a region above the groundwater level (Lw) and including the contaminated region (Gp). The metal frame (2) is installed, and the excavated soil (Gc) is transported to the contaminated soil treatment facility and detoxified. Next, the bottom (Gcb) and side surface ( Soil in the solidified region (Gc) surrounded by Gcs) By conveying drilling, the vertical shaft (40) extending downwardly, and pumping More excavated groundwater level (Lw) below the area placed a metal frame (2), bottom (Gcb) Pump ( 11) is installed, and a water treatment device (10) connected to the ground surface (30f) by a pumping pump (11) and a pumping pipe (12) is installed.

Moreover, according to the present invention, in the contaminated soil purification method for purifying contaminated soil existing below the groundwater level (Lw), the bottom is located below the groundwater level (Lw), which is below the contaminated area (Gp). (Gcb) is solidified, and the side surface part (Gcs) is solidified between the peripheral part of the bottom part (Gcb) and the groundwater level (Lw), and the contaminated area (Gp) below the groundwater level (Lw). Was excavated by excavating the vertical shaft (40) in a range above the groundwater level (Lw) and including the contaminated region (Gp), surrounded by the bottom (Gcb) and the side surface (Gcs). The metal frame (2) is installed in the area, and the excavated soil (Gc) is transported to the contaminated soil treatment facility and detoxified, and then the bottom (Gcb) and side surface in the area below the groundwater level (Lw) Solidified region (Gc) surrounded by part (Gcs) By conveying excavated soil, the vertical shaft (40) extending downwardly, and a metal frame (2) is placed from the lower region excavated groundwater level (Lw), the said bottom (Gcb) A through hole (Hb) is formed, and a pumping pump (11) is arranged in the through hole (Hb) to pump out spring water.

And according to this invention, in the contaminated soil purification construction method for purifying the contaminated soil which exists below the groundwater level (Lw), the bottom is located below the groundwater level (Lw) which is below the contaminated area (Gp). (Gcb) is solidified, and the side surface part (Gcs) is solidified between the peripheral part of the bottom part (Gcb) and the groundwater level (Lw), and the contaminated area (Gp) below the groundwater level (Lw). Was excavated by excavating the vertical shaft (40) in a range above the groundwater level (Lw) and including the contaminated region (Gp), surrounded by the bottom (Gcb) and the side surface (Gcs). The metal frame (2) is installed in the area, and the excavated soil (Gc) is transported to the contaminated soil treatment facility and detoxified, and then the bottom (Gcb) and side surface in the area below the groundwater level (Lw) Solidified region (Gc) surrounded by part (Gcs) By transporting the soil of the inner drilling to, the vertical shaft (40) extending downwardly, and a metal frame (2) is installed from the excavated ground water level (Lw) in the area below the solidification region (Gc ) The inspection of the space of the metal frame (2) in the inside is performed, and the pollutants are measured.

Furthermore, according to the present invention, in the contaminated soil purification method for purifying the contaminated soil existing below the groundwater level (Lw), the region above the groundwater level (Lw) and the contaminated region (Gp) The metal frame (2) is installed in the excavated area by excavating the vertical shaft (40) in the range including the soil, and the excavated soil (Gc) is transported to the contaminated soil treatment facility and detoxified, and the contaminated area The bottom (Gcb) is solidified below the groundwater level (Lw) which is below (Gp), and the side surface (Gcs) is solidified between the peripheral edge of the bottom (Gcb) and the groundwater level (Lw). Then, the contaminated area (Gp) below the groundwater level (Lw) is surrounded by the bottom part (Gcb) and the side part (Gcs), and the bottom part (Gcb) and the side part are below the groundwater level (Lw). Solidified region (Gc) surrounded by (Gcs) By transporting the soil of the inner drilling to, the vertical shaft (40) extending downwardly, and a metal frame (2) is placed from the lower region excavated groundwater level (Lw), the bottom (Gcb) A pumping pump (11) is installed, and a water treatment device (10) connected to the ground surface (30f) by a pumping pump (11) and a pumping pipe (12) is installed.

  And according to this invention, solidification of the said bottom part (Gcb) and a side part (Gcs) is performed by a freezing construction method.

According to the present invention having the above-described configuration, it is solidified so as to surround a contaminated area having a depth deeper than the groundwater level (Lw) (an area below the groundwater level Lw and contaminated). A region to be solidified (solidified region Gc) is formed by a material (for example, by injecting a solidified material and cutting and mixing the in-situ soil), and the region solidified with the solidified material (Gc) does not transmit groundwater. So spring is suppressed.
That is, since the contaminated area (Ewp), which is an area below the groundwater level Lw, is surrounded by the solidified area (Gc), the enclosed area (outside the solidified area Gc) It is difficult for the groundwater to penetrate through the solidified region (Gc) even if the groundwater pressure in the region is high. Therefore, even when excavating a contaminated area (Ewp) below the groundwater level Lw, spring water is suppressed and excavating easily and safely to an area deeper than the groundwater level (Lw). I can do it.

Here, the technique of solidifying the soil with the solidifying material can suppress the cost as compared with the technique of solidifying the soil by passing the frozen material. Therefore, according to the present invention, it is possible to reduce the cost required for the purification of contaminated soil in a region deeper than the groundwater level (Lw).
In addition, according to the present invention, by appropriately selecting a solidifying material, spring water is prevented to such an extent that excavation is not hindered, and spring water for a period required for a finished shape measurement in an area from which contaminants have been removed is obtained. In addition to being prevented, the pressure on the environment can be reduced.

Here, instead of solidifying the soil with the solidifying material, if the soil in the region below the groundwater level (Lw) is frozen by the frozen material and solidified, the frozen soil (Gf) does not permeate the groundwater. Since no spring water is generated when excavating the frozen soil (Gf), it is possible to excavate to a region deeper than the groundwater level (Lw) safely and easily.
In addition, if the soil in the region below the groundwater level (Lw) and surrounding the contaminated region (Ewp) is frozen and solidified by freezing material, the frozen soil (Gf ) Is restored to its original state (thawed), the original water permeability of the soil is restored. Therefore, after the ring-shaped metal frame (2) is removed, the ring-shaped metal frame (2) is removed after a certain period of time without drilling the frozen soil remaining outside the metal frame (2). Groundwater can enter the space after removal.

According to the present invention, only the region surrounded by the metal frame (2) is excavated, and the range to be excavated is limited. Therefore, a relatively small machine or Excavation is possible only by workers, and it is possible to excavate deeper.
Here, when the construction site is a narrow area such as an urban area, if a large heavy machine such as a large crane is brought in for construction, vibration and noise during construction become a problem. Also, assuming an accident such as a heavy machine falling, there is a high risk of serious damage to surrounding buildings. On the other hand, in this invention, since a large sized heavy machine is unnecessary, it is not necessary to assume such a danger.

And according to this invention which does not require a large sized heavy machine, it is possible to construct in a narrow area | region, such as an operating facility.
In the prior art, when excavating from the surface when purifying contaminated soil reaching the deep layer, it is necessary to excavate a space having an inclination angle less than the soil repose angle. As a result, a large amount of excavated soil is generated.
On the other hand, according to the present invention, by installing the metal frame (2), the excavation site can be suppressed to a small scale, and the amount of excavated soil can be drastically reduced. That is, according to the present invention, since the construction area is surrounded by the ring-shaped metal frame (liner ring 2), the excavated shaft is provided even if the excavated shaft does not have an inclination angle less than the soil repose angle. Will not collapse.
Further, the metal frame (2) is obtained by assembling a plurality of arc-shaped parts by a publicly known method. Therefore, assembly and disassembly are easy.

It is sectional drawing which shows the state where the pollution area | region has reached | attained the area | region deeper than a groundwater level and there is no flow in groundwater. In embodiment of this invention, it is a figure which shows the state which removed the building on the ground. In embodiment, it is sectional drawing which shows the state which solidified the disk-shaped bottom part under a contamination area | region. In embodiment, it is a peripheral part of the bottom part shown in FIG. 3, Comprising: It is sectional drawing which shows the state which solidified the side part below a groundwater level. It is the top view seen from the groundwater level which shows the relative positional relationship of a side part and a bottom part. Process drawing which shows the initial state of shaft excavation and liner ring installation in embodiment. Process drawing which shows the state after FIG. 6 of shaft excavation and liner ring installation in embodiment. In embodiment, process drawing which shows the state which the shaft excavation and liner ring installation in the area | region above a groundwater level were completed. In embodiment, it is a figure which shows the state which excavates a shaft in the area | region below a groundwater level, and installs a liner ring. In embodiment, it is process drawing which shows the state which the shaft excavation and liner ring installation of the contaminated area were completed. In an embodiment, it is a figure showing the state where lift up force acts in the case of finished form inspection. FIG. 12 is a diagram illustrating an example in which the finished shape is not damaged by the lift-up force illustrated in FIG. 11. In the modification of embodiment, it is a figure which shows the state immediately before solidifying so that the contamination area | region below a groundwater level may be surrounded. It is sectional drawing explaining the aspect which a contamination area | region spreads. It is explanatory drawing explaining the outline | summary of the technique which purifies the contamination area | region shown in FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows the state of soil contamination before the embodiment is carried out.
In FIG. 1, in the factory 20, the pollutant leaks due to the damage of the tank (not shown), and the pollutant penetrates deep into the soil G, and the tip of the contaminated area Gp is below the groundwater level Lw. It extends to the area.
Here, 1st Embodiment of FIGS. 1-12 addresses the case where the flow of groundwater does not exist, and the contaminant of the contamination area | region Gp has not spread | diffused in the horizontal direction.

As described above, since the pollutant moves downward between the soil particles by the action of gravity, the soil contaminated region Gp does not spread so much in the left-right direction in FIG. 1 and penetrates downward in FIG. Therefore, the contaminated area Gp reaches a deep underground area.
In FIG. 1, the soil G is shown with hatching, and a white portion not hatched is a region Gp contaminated with a contaminant. Moreover, in FIG. 1, the code | symbol Lw has shown the groundwater level, the code | symbol 30f has shown the ground surface, the code | symbol Ep has shown the area | region which should implement embodiment, and the code | symbol Ewp has shown the construction area below the groundwater level Lw. Show.

The construction of the embodiment is performed with the factory 20 removed as shown in FIG. However, not all buildings in the factory 20 have to be removed. It is sufficient to remove the building that exists immediately above the contaminated area Gp.
Specifically, equipment (not shown) required for solidification of the region Gc (FIG. 6: bottom Gcb and side surface Gcs) that is below the groundwater level Lw described in FIG. 3 and surrounds the contaminated region Gp. To the position immediately above the contaminated area Gp and the building may be removed to such an extent that it can be installed.

Next, as shown in FIG. 3, the region Gcb (bottom) below the contaminated region Gp below the groundwater level Lw is solidified. The bottom Gcb is a disc-shaped region, for example. However, it may be a square or other flat plate shape.
In the step shown in FIG. 3, a solidifying material, for example, a grout material, is supplied to the disk-shaped bottom Gcb below the groundwater level Lw by means not shown, for example, injection means or injection means.
In FIG. 3, in solidifying the disk-shaped bottom Gcb below the groundwater level Lw, a ground improvement device (not shown) is installed immediately above the contaminated area Gp, and a construction method according to a known technique is applied. The region below Lw is solidified. For example, a so-called pouring method, a so-called grout method, a freezing method, or the like can be applied as a method according to a known technique. The “grouting method” is a method for forming an underground solid body by supplying a solidifying material (grouting material) and cutting the soil while stirring and mixing the solidifying material and the soil.
Here, the grout material is exemplified as an example of the solidifying material, and other solidifying materials such as various chemicals, cement milk, and the like can be used.

If the bottom Gcb is solidified, as shown in FIG. 4, the region (side surface) Gcs between the peripheral edge of the bottom Gcb and the groundwater level Lw is solidified. By solidifying the side surface portion Gcs, the contaminated region Gp below the groundwater level Lw is surrounded by the bottom portion Gcb and the side surface portion Gcs. In the present specification, the bottom portion Gcb and the side surface portion Gcs may be comprehensively expressed as “solidified soil Gc” or “solidified region Gc”.
In FIG. 4, the region surrounded by the bottom Gcb and the side surface Gcs, and the region other than the contaminated region Gp is in the same state as the region Gw below the groundwater level Lw.

FIG. 5 shows a state in which the side surface portion Gcs is viewed from the groundwater level Lw. For example, as shown in FIG. 5, the side surface portion Gcs is composed of a plurality of columnar underground solid bodies that are continuously formed on the periphery of the bottom portion Gcb.
When the side surface portion Gcs is formed, for example, the peripheral portion of the bottom portion Gcb is excavated with an auger to reach the bottom portion Gcb. Then, in the region between the groundwater level Lw and the bottom Gcb, a solidified material is injected from the tip of the auger, and the solidified material and the in-situ soil are kneaded by rotation of the auger. Create. If a plurality of the cylindrical underground solid bodies are formed so as to surround the periphery of the bottom portion Gcb, the side surface portion Gcs is built.

If the solidified region Gc is solidified so as to include the contaminated region Gp below the groundwater level Lw (FIGS. 4 and 5), the region above the groundwater level Lw and including the contaminated region Gp Is excavated (FIG. 6).
In excavation, as shown in FIG. 6 and FIG. 7, a range that is an area above the groundwater level Lw and includes the contaminated area Gp is determined from the ground surface 30 f so as to have a circular cross section. The shaft 40 is excavated to a depth. When excavating to a predetermined depth, the liner ring 2 is installed in the excavated area.

FIG. 6 shows a state where the second stage liner ring 2 is installed from the ground surface 30f, and FIG. 7 shows a state where the fourth stage liner ring 2 is installed from the ground surface 30f.
6 and 7, for excavation of the vertical shaft 40, the small excavator 1 (for example, a self-propelled small backhoe) is used to excavate from the ground surface 30f downward in the vertical direction of the soil.
Excavated soil Go (including contaminated soil) is transported to a contaminated soil treatment facility (not shown) by, for example, a dump truck (vehicle) 3 or a belt conveyor (not shown) installed on the ground side, and detoxified by a known method. Is done.
When excavating the vertical shaft 40, the small excavating machine 1 excavates a depth corresponding to, for example, the vertical dimension hr of the liner ring 2 (a depth corresponding to one stage of the liner ring 2). One ring 2 is installed. Hereinafter, the excavation of the shaft 40 and the installation of the liner ring 2 are repeated alternately.

Here, the depth at which the shaft 40 is excavated is not limited to the depth hr of one stage of the liner ring 2. For example, the shaft 40 may be excavated by a depth corresponding to two stages of the liner ring 2 (dimension 2 hr), and the liner ring 2 may be installed in two stages in the shaft 40.
That is, when excavating the vertical shaft 40, the vertical shaft 40 is excavated to the depth of n stages of the liner ring 2, and in step S2, the liner ring 2 is installed in n stages so as to cover the inner wall surface of the excavated vertical shaft 40. I can do it. In other words, when the shaft 40 is excavated and the liner ring 2 is installed, the number n of the above-described liner ring 2 is not only 1, but is 2 or more as long as the excavated shaft 40 may not collapse. It may be a natural number.

In the state shown in FIG. 8, the shaft 40 is excavated in the region above the groundwater level Lw and including the contaminated region Gp, and the liner ring 2 is installed.
Here, in FIG. 8, the five stages of the liner ring 2 are simply expressed in order to avoid the complexity of the illustration. In actual construction, the number of installation stages of the liner ring 2 until reaching the groundwater level Lw is a very large value.
At the stage where the liner ring 2 is installed up to the groundwater level Lw, the contaminated soil in the contaminated region Gp above the groundwater level Lw is excavated and transported to the ground side. And as demonstrated in FIG. 4, the contamination area | region Gp below the groundwater level Lw is the state enclosed by the solidification area | region Gc.

Next, as shown in FIG. 9, the soil in the region below the groundwater level Lw and the region surrounded by the solidified region Gc is excavated, and the region below the groundwater level Lw is excavated. The shaft 40 is extended downward. And the liner ring 2 is installed in the area | region (area | region which extended the shaft 40 below) lower than the drilled groundwater level Lw.
Here, the solidified region Gc has low water permeability, and the groundwater around the solidified region Gc cannot enter the region surrounded by the solidified region Gc. For this reason, even if the region surrounded by the solidified region Gc is excavated, groundwater does not spring out from the excavation point. Therefore, it is prevented that the excavation of the area deeper than the groundwater level Lw becomes difficult due to the spring water, and the excavation can be easily performed even in the area below the groundwater level Lw.

Further, since the inner wall surface Dco of the solidified region Gc is difficult to collapse, the liner ring 2 is excavated for one stage as in the construction of the region above the groundwater level Lw (FIGS. 6 and 7). There is no need to repeat the installation of 2 only one stage. For example, after the excavation in the area surrounded by the solidified soil Gc is completed, the liner ring 2 can be installed over the entire area surrounded by the solidified soil Gc.
Of course, if there is a possibility that the area Dco where the solidified soil Gc has been excavated may collapse due to a high earth pressure, the solidified soil Gc is excavated to the depth of one stage (or more than two stages) of the liner ring 2. However, the liner ring 2 may be installed one stage (or two or more stages). When the liner ring 2 is installed one stage (or two or more stages), the area surrounded by the liner ring 2 is excavated.
In FIG. 9, the state which has installed the liner ring 2 in the area | region enclosed by the solidified soil Gc is shown.

The mixture of the contaminated soil excavated from the solidified soil Gc and the solidified material is transported to the ground side 30 in the same manner as in the steps of FIGS. 6 and 7, and is separated from the contaminants and detoxified by a contamination treatment facility (not shown).
In the process shown in FIG. 9, the pollutant is removed from the groundwater level Lw deep region by excavating the contaminated soil in the contaminated region Gp deep in the groundwater level Lw and carrying it to the ground side 30.

FIG. 10 shows a state where the soil below the groundwater level Lw is excavated and the liner ring 2 is installed. In the state of FIG. 10, the liner ring 2 is installed inside the solidified region Gc.
At this stage, there is a case where it is necessary to confirm and inspect (inspected) a space (made shape) inside the solidified region Gc. In such a case, in the space (finished shape) in the radial direction of the area where the liner ring 2 is installed in the solidified area Gc, a contaminant such as VOC is measured to confirm that the contaminant has been removed. Check it.

In FIG. 10, a pumping pump 11 is installed at the bottom of the finished shape in order to discharge water in which spring water or the like is accumulated.
The ground surface 30f in the vicinity of the construction area 1 is provided with a water treatment device 10 for storing the groundwater pumped by the pumping pump 11 and processing it if necessary. The water treatment device 10 and the pumping pump 11 Are connected by a pumping pipe 12.

  Here, in the state where the contaminated soil in the contaminated area Gp deep in the groundwater level Lw is excavated and carried to the ground side 30, as shown in FIG. 11, an upward force (so-called “lift up” is applied to the bottom Gcb. "Force": indicated by a plurality of arrows Fu) acts. The lift-up force Fu increases as the bottom Gcb is positioned below the groundwater level Lw, and in some cases, the bottom Gcb of the solidified region Gc may be damaged or may crack. If the bottom Gcb is damaged, there is a possibility that it will hinder the finished shape inspection.

In order to prevent the bottom Gcb from being damaged by the lift-up force Fu, as shown in FIG. 12, a through hole Hb may be formed in a part of the bottom Gcb (for example, the center). If such a through hole Hb is formed, the groundwater pressure is released from the through hole Hb, so that the lift-up force is also reduced as shown by the arrow Fsm in FIG.
According to the inventor's experience, the amount of groundwater (the amount of spring water) flowing into the space (made-up) inside the solidified region Gc from the through hole Hb is small and does not adversely affect the made-up inspection. However, when the amount of spring water from the through hole Hb is large, as shown in FIG. 12, the pump 11 may be disposed in the through hole Hb to pump the spring water to the ground side.

In the embodiment, although not clearly shown, when the measurement and other operations are finished, the liner ring 2 disposed at the deepest position is removed. Since the liner ring 2 is constituted by connecting a plurality of arc-shaped liner pieces, the liner ring 2 at the deepest position (lowermost position) can be removed by releasing the connection of the liner pieces.
After the liner ring 2 is removed, the area from which the liner ring 2 has been removed is backfilled with high-quality soil in order to prevent the excavation hole from collapsing. The high quality soil that is the backfilling material may be backfilled to the original position after decontamination of the contaminated soil excavated in the steps of FIGS. Or you may use the soil which is the clean soil supplied from other than a construction area | region, and does not exert an environmental influence with respect to a construction area | region.

When removing the liner ring 2 and backfilling the shaft 40, the liner ring 2 is removed, for example, one step at a time. However, if the shaft 40 does not collapse between the removal of the liner ring 2 and the backfilling with good quality soil, it is possible to remove the two or more stages of the liner ring 2 at a time.
If the liner ring 2 has been removed to the top level (surface side), in other words, if the liner ring 2 has been removed to the ground surface, the construction is completed.

1 to 12, in the contaminated area Gp above the groundwater level Lw, an area surrounded by the liner ring 2 (contaminated soil area) is excavated, and the excavated contaminated soil is grounded. By sending it to the side and treating it, the pollutant can be removed from the ground together with the contaminated soil, and the construction area can be purified.
On the other hand, the contaminated area Gp below the groundwater level Lw is surrounded by the solidified area Gc, the inner area surrounded by the solidified area Gc is excavated, and the excavated contaminated soil is sent to the ground side for processing. By doing so, the contaminants are removed from the ground together with the contaminated soil, and the construction area is purified.

Here, the region deeper than the groundwater level Lw is difficult to excavate because of spring water.
On the other hand, according to the first embodiment, the contaminated region Gp below the groundwater level Lw is surrounded by the solidified region Gc, and the solidified region Gc has low water permeability. It is not possible to enter inside the area surrounded by Therefore, it is possible to suppress spring water when excavating a region deeper than the groundwater level Lw.
Here, soil solidification technology by supplying solidification material is less costly and shorter in construction period than other technologies, such as construction methods that prevent the spring water by building impermeable walls etc. It is advantageous.

Here, by appropriately selecting the solidification material, the spring water is suppressed to such an extent that excavation is not hindered, and the spring water is suppressed only for the period required for the finished shape measurement in the area where the pollutants are removed. It is possible to reduce the influence on the environment.
According to such a viewpoint, when a grout material is used as the solidifying material, the range of the hydraulic conductivity k is preferably 1 × 10 ⁻⁵ cm / s to 1 × 10 ⁻⁶ cm / s, for example. .

In the embodiment, in the steps shown in FIGS. 6 to 8, the contaminated area Gp is excavated by a small excavating machine, for example, a backhoe. However, although not shown, excavation by a worker's manual work or excavation by human power may be used.
6 to 8 of the first embodiment of FIGS. 1 to 12 are configured to excavate only the region surrounded by the liner ring 2, and the range Ep to be excavated is limited. Therefore, it is possible to excavate to a deep region with only a simple machine or a worker without using heavy machinery.
Since a large heavy machine is not required and is performed only in a narrow region surrounded by the liner ring 2, the amount of excavated soil is minimized in the steps shown in FIGS. 6 to 8 of the first embodiment of FIGS. In addition, the construction area can be minimized. Therefore, for example, in a facility in operation, it is possible to purify contaminated soil under a condition where the construction area is narrow.

  In the steps shown in FIGS. 6 to 8 of the embodiment, since the liner ring 2 is stacked and installed, the liner ring 2 acts as a rigid mountain retaining wall so that the deeper region is formed. Even if excavated up to, the excavated vertical shaft 40 will not collapse. Therefore, it becomes possible to excavate without providing a slope. Therefore, the amount of excavated soil can be minimized, and efficient construction can be performed for the contaminated area.

  Furthermore, the liner ring 2 used in the embodiment is assembled by connecting a plurality of arc-shaped liner pieces. Therefore, assembly and disassembly of the liner ring 2 can be easily performed by a known technique.

Here, in the embodiment of FIGS. 1 to 12, after the bottom Gcb and the side surface Gcs are solidified so as to surround the contaminated area Gp deeper than the groundwater level Lw, the shaft 40 is drilled in the shallow area of the groundwater level Lw. However, in the modification of the embodiment shown in FIG. 13, after the shaft 40 is drilled in the region where the groundwater level Lw is shallow and the liner ring 2 is installed, the depth below the groundwater level Lw is set. The bottom portion Gcb and the side surface portion Gcs are solidified so as to surround the contaminated region Gp.
FIG. 13 shows a state in which the shaft 40 is excavated in a region above the groundwater level Lw (including a contaminated region above the groundwater level Lw) and the liner ring 2 is installed. And in the state of FIG. 13, the contaminated area | region Gp remains in the area | region below the groundwater level Lw.

From the state of FIG. 13, as shown in FIGS. 3 and 4, the bottom Gcb and the side part Gcs are solidified so as to surround the contaminated area Gp below the groundwater level Lw, and as shown in FIG. 9, the solidified area Gc The shaft 40 is excavated in a region below the groundwater level Lw surrounded by the above, and the liner ring 2 is installed so as to be in the state shown in FIG.
Other configurations and operational effects in the modification of FIG. 13 are the same as those of the embodiment of FIGS.

It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.
For example, the illustrated embodiment describes the case where the solidified region Gc surrounding the contaminated region existing below the groundwater level Lw is formed by supplying a solidified material. However, as described above, the spring water used for excavating the contaminated area below the groundwater level Lw by freezing the part surrounding the contaminated area below the groundwater level Lw by the so-called freezing method. Can be suppressed.

DESCRIPTION OF SYMBOLS 1 ... Small excavation machine 2 ... Liner ring 3 ... Conveyance machine / small dump truck 5 ... Through-hole 6 ... Pump 10 ... Contaminated water treatment apparatus 11 ... Pumping pump 30.・ ・ Ground side 40 ・ ・ ・ Vertical shaft Lw ・ ・ ・ Ground water level Gcb ・ ・ ・ Bottom part Gcs ・ ・ ・ Side part Gc ・ ・ ・ Solidification area Gp ・ ・ ・ Contamination area

Claims (5)

In the contaminated soil purification method for purifying the contaminated soil existing below the groundwater level (Lw), the bottom (Gcb) is solidified below the groundwater level (Lw) below the contaminated area (Gp), and The side surface portion (Gcs) is solidified between the peripheral edge portion of the bottom portion (Gcb) and the groundwater level (Lw), so that the contaminated region (Gp) below the groundwater level (Lw) is the bottom portion (Gcb) and the side surface portion. (Gcs) and a metal frame (2) in the area excavated by excavating the shaft (40) in a range above the groundwater level (Lw) and including the contaminated area (Gp). The soil (Gc) that was installed and excavated during that time was transported to the contaminated soil treatment facility and detoxified, and then surrounded by the bottom (Gcb) and the side (Gcs) in the region below the groundwater level (Lw). It conveyed excavated soil in the solidified region (Gc) The Rukoto, the vertical shaft (40) extending downwards, and from the excavated ground water level (Lw) below the area placed a metal frame (2), the water pumps (11) placed on the bottom (Gcb) A contaminated soil purification method characterized by installing a water treatment device (10) connected to the ground surface (30f) by a pumping pump (11) and a pumping pipe (12). In the contaminated soil purification method for purifying the contaminated soil existing below the groundwater level (Lw), the bottom (Gcb) is solidified below the groundwater level (Lw) below the contaminated area (Gp), and The side surface portion (Gcs) is solidified between the peripheral edge portion of the bottom portion (Gcb) and the groundwater level (Lw), and the contaminated region (Gp) below the groundwater level (Lw) is defined as the bottom portion (Gcb) and the side surface portion. (Gcs) and a metal frame (2) in the area excavated by excavating the shaft (40) in a range above the groundwater level (Lw) and including the contaminated area (Gp). The soil (Gc) that was installed and excavated during that time was transported to the contaminated soil treatment facility and detoxified, and then surrounded by the bottom (Gcb) and the side (Gcs) in the region below the groundwater level (Lw). It conveyed excavated soil in the solidified region (Gc) The Rukoto, the vertical shaft (40) extending downwardly, and a metal frame (2) is placed from the lower region excavated groundwater level (Lw), forming a through hole (Hb) to said bottom (Gcb) And the contaminated soil purification method characterized by arrange | positioning a pumping pump (11) in a through-hole (Hb), and pumping out spring water. In the contaminated soil purification method for purifying the contaminated soil existing below the groundwater level (Lw), the bottom (Gcb) is solidified below the groundwater level (Lw) below the contaminated area (Gp), and The side surface portion (Gcs) is solidified between the peripheral edge portion of the bottom portion (Gcb) and the groundwater level (Lw), so that the contaminated region (Gp) below the groundwater level (Lw) is the bottom portion (Gcb) and the side surface portion. (Gcs) and a metal frame (2) in the area excavated by excavating the shaft (40) in a range above the groundwater level (Lw) and including the contaminated area (Gp). The soil (Gc) that was installed and excavated during that time was transported to the contaminated soil treatment facility and detoxified, and then surrounded by the bottom (Gcb) and the side (Gcs) in the region below the groundwater level (Lw). It conveyed excavated soil in the solidified region (Gc) The Rukoto, vertical shaft (40) and an extended downward, and drilled metal frame below the area from the groundwater level (Lw) and (2) is installed, the metal frame of the solidified region (Gc) (2) Contaminated soil remediation method, characterized by performing a check inspection of the space and measuring pollutants. In the contaminated soil purification method for purifying the contaminated soil existing below the groundwater level (Lw), the vertical shaft (40) is in the range above the groundwater level (Lw) and including the contaminated region (Gp). ) And the metal frame (2) is installed in the excavated area, during which the excavated soil (Gc) is transported to the contaminated soil treatment facility and detoxified, and the groundwater below the contaminated area (Gp) The bottom (Gcb) is solidified below the position (Lw), and the side surface (Gcs) is solidified between the peripheral edge of the bottom (Gcb) and the groundwater level (Lw), from the groundwater level (Lw) The lower contaminated region (Gp) is surrounded by the bottom (Gcb) and the side surface (Gcs), and is solidified by being surrounded by the bottom (Gcb) and the side surface (Gcs) in the region below the groundwater level (Lw). transport and drilling the soil in the region (Gc) The Rukoto, the vertical shaft (40) extending downwards, and from the excavated ground water level (Lw) below the area placed a metal frame (2), the water pumps (11) placed on the bottom (Gcb) A contaminated soil purification method characterized by installing a water treatment device (10) connected to the ground surface (30f) by a pumping pump (11) and a pumping pipe (12). The contaminated soil purification method according to any one of claims 1 to 4, wherein the bottom portion (Gcb) and the side surface portion (Gcs) are solidified by a freezing method.

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