JP4528080B2 - Purification method of contaminated soil, underground structure and underground structure - Google Patents

Description

  The present invention relates to a method for purifying contaminated soil using a pneumatic caisson method, and in particular, purifies soil on land contaminated with a volatile organic compound (hereinafter referred to as VOC) on-site (on-site), The present invention relates to a method of constructing an observation well for investigating the underground structure and underground structure such as the foundation of the structure and the underground facilities provided in the purified land, and the state of the land that has been backfilled after the purification.

  Soil contamination due to VOC has only been revealed for about 10 years, and various new technologies have been tried as purification methods, but the main technologies are purification in-situ and purification by excavation and removal. It is divided roughly into.

  The in-situ purification process is further classified into in-situ extraction and in-situ decomposition methods. The in-situ extraction method is a technology that identifies the position of pollutants in the soil, extracts the pollutants at that location, constructs equipment to perform the purification process, and then extracts the contaminants from the soil and performs the purification process. . In-situ decomposition method, after confirming the decomposition route and the behavior of the decomposition product in the appropriate test etc. in advance, the equipment for injecting the decomposition product into the soil is built in the place, and the decomposition product is put into the soil. It is a technology for injecting and purifying.

  The in-situ purification process is a relatively time-consuming method because both the in-situ extraction and in-situ decomposition techniques are performed by the above process. In addition, when building foundations and underground facilities on land that has undergone in-situ purification processing, soil purification is included in order to excavate soil and build underground structures after purification processing. This is a time consuming method.

The purification treatment method by excavation and removal is a technique for excavating contaminated soil and removing the contaminants by applying heat to the excavated soil. When constructing foundations and underground facilities for land to be purified by excavation and removal, it is carried out through the steps of removing contaminated soil, constructing underground structures, purifying contaminated soil, and backfilling purified soil. This is a relatively time-consuming technology. In addition, purification of excavated contaminated soil is broadly divided into cases where it is performed on-site (in the field) and cases where it is performed off-site (outside the field). When it is carried out on-site (on site), it is necessary to secure a space for temporarily storing the purification treatment equipment, excavated contaminated soil and purified soil, and it becomes difficult to perform construction in a small land. When purification treatment is performed off-site (off-site), there are few recipients of contaminated soil, and depending on the recipients, treatment costs increase. There is also a problem that there is a concern about the diffusion of pollutants in the transportation route. In addition, there exists patent document 1 as this type of prior art.
JP 2003-103244 A

The present invention is proposed in view of the above-mentioned problems. By adopting the pneumatic caisson method for the purification treatment of soil contaminated with VOC, it is possible to perform construction in a shorter period of time than conventional techniques. And a method capable of carrying out the purification treatment of pollutants on-site (on site) with compact equipment, and in particular, simultaneously with the purification treatment of soil contaminated with VOC In the case of constructing the foundations of structures and underground facilities on the same land, the purpose is to enable construction and compact processing facilities in a shorter period of time than conventional techniques.

  In order to achieve the above object, the present invention is configured as follows.

Purification treatment method contaminated soil according to the first invention, using a pneumatic caisson method as drilling methods the soil contaminated with VOC, comprises a working chamber ceiling plate blade die was at its lower end provided with a peripheral wall portion on the outer periphery of the An excavator that can be remotely controlled from the ground is installed in the work room of the reinforced concrete frame (caisson frame) for forming the work chamber, and the excavator excavates the contaminated soil under the caisson and exposes it to the air. The VOC is discharged from the soil, and the discharged VOC polluted gas and the contaminated water are guided to the purification processing equipment installed on the ground and purified, and the excavated soil from which the VOC has been discharged is subsided with the caisson enclosure. It is characterized by discharging to the upper side of the board .

  According to a second invention, in the first invention, the VOC discharged by agitating the VOC-contaminated soil and exposing it to air is supplied to the purification equipment through a pipe connecting the caisson work room and the purification equipment installed on the ground. And performing a purification process.

The third invention is the first or second aspect of the invention, the pressure difference generated by the cutting edge depth of water pressure caisson blade die which act by pressure and groundwater level of the working chamber, the pressure in the working chamber is reduced By adjusting as described above, groundwater contaminated with VOCs is submerged in the work chamber, and water is sent to the purification equipment through a pipe connecting the caisson work room and the purification equipment installed on the ground by a submersible pump to perform purification treatment. Thus, it is possible to collect and purify the pollutants without dissipating them.

The fourth invention, in any one of the first to third inventions, when it is known in advance that a ground structure such as a foundation of a structure or an underground facility is constructed as a use application of the land to be purified. As the concrete frame for working room formation by excavation under the caisson is set up , an upper reinforced concrete frame is constructed at the upper end of the concrete frame, and the contaminated soil is purified by discharging the purified excavated soil inside the upper reinforced concrete frame. It is characterized by parallel processing and construction of underground structures.

In the fifth invention, in any one of the first to third inventions, the use of the purified land is undecided, and in the implementation only for the purification of the land, only the reinforced concrete frame forming the working room is excavated. and sinking, characterized by a state of the soil was cleaned processes after sinking the concrete skeleton by backfilling the excavation soil was cleaned on the upper side of the working chamber ceiling plate by sinking of the concrete skeleton.

A sixth invention is characterized in that, in any one of the first to fourth inventions, an observation well for periodically investigating the state of the backfilled soil is constructed along with the set-up of the reinforced concrete frame. And
The seventh invention is the purification treatment method for contaminated soil according to any one of the first to third inventions and the fifth invention, wherein an observation well for periodically investigating the state of the backfilled soil is provided. It is constructed with the construction of the reinforced concrete frame.

An eighth invention is a structure constructed as an underground structure such as a foundation or an underground facility by the purification treatment method according to any one of the first to fourth and sixth inventions, and forms a work chamber. The upper reinforced concrete frame is continuously provided on the upper part of the reinforced concrete frame, and the excavated soil after the VOC is discharged is discharged into the upper reinforced concrete frame.

A ninth invention is an underground structure in which the purification treatment method according to any one of the first to third, fifth, and seventh inventions is carried out only for the purification of land, and a working chamber is provided. inner reinforced concrete skeleton to be formed is, that over a range of being sinking to the deepest layer of VOC contaminated soil from the upper surface of the working chamber ceiling plate after sinking the reinforced concrete skeleton to the ground, and is surrounded by the outer shape of the caissons skeleton Is backfilled with excavated soil after the VOC has been released.

(1) It becomes possible to purify soil contaminated with VOCs without affecting the surroundings, and the environment can be kept safe.
(2) Since the soil excavated and purified is directly discharged into the caisson enclosure, the soil can be treated without requiring a space for temporarily placing the excavated soil.
(3) If it is known in advance that an underground structure and observation wells will be built on the land to be purified, the reinforced concrete underground structure and By constructing an observation well, construction can be completed in a shorter period of time than conventional methods.

  Embodiment 1 of the purification process of the soil contaminated with VOC and the construction method of an underground facility is demonstrated with reference to FIGS. FIG. 1 is a vertical cross-sectional view of a concrete caisson housing for purifying soil 4b contaminated with VOCs, FIG. 2 is a side view showing an embodiment of a ground VOC purification facility, and FIG. 3 is a caisson. FIG. 4 is a longitudinal sectional view of the process of removing the caisson subsidence facility after the enclosure is installed, and FIG. 4 is a longitudinal sectional view after the construction of the underground structure.

In the present invention, excavation of soil 4b contaminated with VOC and construction of an underground structure are performed by a pneumatic caisson method. In this method, first, a concrete casing 1b that forms the working chamber 2 is constructed on the ground surface 4 on the soil 4b contaminated with VOC (FIG. 1 shows a mode in which the casing 1b sinks to a predetermined depth. ). Then, while excavating the soil 4b contaminated with VOC, the concrete casing 1b forming the working chamber 2 is subsidized, and the upper reinforced concrete casing 1c is connected to the upper end 14 of the working chamber forming casing 1b, thereby finally The reinforced concrete frame 1 shown in FIG. 1 is completed. In Figure 1, the working chamber formed concrete skeleton 1b is a structure in which an outer peripheral wall 16 blades spinneret was 7 formed at the lower end of the working chamber ceiling plate 15, the working chamber 2 is formed inside .

The working chamber 2, as well as deploy the excavator 3 for drilling soil 4, the working chamber on the upper side of the ceiling plate 15, a human for and out system 10 and the material for loading and unloading chamber and excavated soil into chamber 2 A carry-in system 11 is provided. People for and out system 10 is constituted by Mann shaft 10b and man lock 10a or the like, the worker can and from the working chamber 2, such as for inspection through the opening 17 of the working chamber ceiling plate 15 by the system 10. Material for loading and unloading chamber and excavated soil loading system 11 includes a material shaft 11b and material locks 11a, etc., excavator 3 and the ground bucket 8, such as below the material and excavated soil through the opening 18 of the working chamber ceiling plate 15 Can be carried in and out. The person entry / exit system 10, the material entry / exit chamber, and the excavated sediment loading / unloading system 11 are the same as the normal pneumatic caisson method, and therefore the details are omitted.

  By excavating the soil 4a under the work room 2 with the excavator 3 provided in the work room 2, the reinforced concrete frame 1 can be set down. The excavator 3 can be remotely operated from the ground, and can excavate the soil 4b contaminated with VOC without entering the work room 2. Since the remote operation from the ground of the excavator 3 is the same as the normal pneumatic caisson method, the details are omitted.

In the unmanned work chamber 2, the soil contaminated with VOC excavated by the excavator 3 is agitated and exposed to air to release VOC. The discharged VOC is sent to the ground purification treatment facility 12 through the pipe 6 embedded when the reinforced concrete frame 1 is constructed. The lower end of the pipe 6 is in communication with the working chamber 2 through the working chamber ceiling plate 15, the upper end is communicated with the cleaning process equipment 12, VOC, which is air for purification treatment facility 12 through the pipe 6 The gas containing is heated by the heater 12f shown in FIG. 2 and then sent to the activated carbon layer 12c to purify the gas by causing the activated carbon to absorb the VOC. The activated carbon that has sucked the VOC is collected and disposed of at the final disposal site. The purified gas is released into the atmosphere.

  The soil that has been purified by discharging the VOC is loaded into the earth bucket 8, transported to the ground through the material shaft 11 b and the material lock 11 a, and discharged into the reinforced concrete frame 1 without being temporarily placed. When the excavated soil 4c discharged in the concrete frame 1 fills the man shaft 10b and the material shaft 11b rising up the concrete frame 1, the concrete shaft 1 is constructed, and then the man shaft 10b and the material shaft 11b are A defect that cannot be removed occurs. In order to eliminate this problem, in the present invention, as shown in FIG. 1, the surroundings of the man shaft 10 b and the material shaft 11 b are surrounded by a gap, and protective tube bodies 19 and 20 are provided. The protective tube bodies 19 and 20 are composed of segments that can be assembled and divided, such as corrugated pipes, and sheet piles.

  In the pneumatic caisson method, compressed air is sent from the ground air supply equipment 9 to the work chamber 2 to keep the atmospheric pressure in the work chamber high in order to prevent groundwater from entering the work chamber. That is, the compressed air supply pipe 9a led out from the air supply facility 9 installed on the ground is branched into first, second, and third branch pipes 9b, 9c, and 9d, and the tip of the branch pipe Compressed air can be sent to the connecting part. The second and third branch pipes 9c and 9d are connected to the manlock 10a and the material lock 11a, respectively, and can send compressed air to each part. The compressed air supply pipe 9e led out from the air supply facility 9 is connected to the aeration tank 12b of the purification treatment facility, and can supply compressed air to the aeration tank 12b alone.

  The first branch pipe 9b communicates with the work chamber 2 through the inside of the reinforced concrete housing 1, and keeps the work chamber 2 at a predetermined pressure so that excavation can be performed without entering the work water 2 into the work chamber 2. . In the present invention, when excavating the soil 4b contaminated with VOC by the excavator 3, the pressure difference caused by the water pressure of the blade edge depth of the blade metal fitting 7 acting by the atmospheric pressure in the working chamber 2 and the groundwater level is slightly increased. By adjusting the air pressure in the work chamber 2 to be low, the ground water 5 contaminated with VOC can be immersed in the work chamber 2. As a result, the groundwater 5 contaminated by the VOC immersed in the work room 2 is sucked by the submersible pump 5a installed in the work room 2, and the ground purification treatment equipment is provided through the pipe 5b embedded when the reinforced concrete frame 1 is constructed. 12 to water.

  As shown in FIG. 2, the groundwater 5 contaminated with the VOC sent to the purification treatment facility 12 through the pipe 5b removes impurities such as earth and sand 21 in the underground water receiving tank 12a, and the earth and sand 21 is accumulated in the sediment earth and sand bit 12e. . The contaminated ground water 22 from which the earth and sand 21 has been removed is sent to the aeration tank 12b by the submersible pump 5a, and the VOC is degassed by exposure to air in the aeration tank 12b. The degassed gas containing VOC is guided to the heater 12f, adsorbed on the activated carbon by the activated carbon layer 12c, purified, and released to the atmosphere. In addition, the contaminated groundwater from which the VOC has been degassed in the aeration tank 12b is sent to the treated water tank 12d. The treated groundwater 22a is treated in this treated water tank 12d, and the detoxified groundwater 22a is discharged into the public underground water system by the submersible pump 5a. Or drain into the well 23 and return to the basement.

  Moreover, as shown in FIG. 1, when providing the observation well 13 for regularly investigating the state of the soil that has been purified and backfilled, the working room is the same as in the construction method of the underground structure 1a. By constructing the observation well 13 along with the subsidence of 2, the observation well 13 can be completed almost simultaneously with the end of the purification process.

After the reinforced concrete frame 1 is laid down to the lowest layer of the soil layer contaminated with VOC (the depth shown in FIG. 1), the earth bucket 8 and the pipes 5b, 6 required for the laying of the reinforced concrete frame 1 are obtained. , 9a, man shaft 10b, man lock 10a, material shaft 11b, material lock 11a, excavator 3, etc. are removed. The protective tube bodies 19 and 20 may be removed last or buried. 3, leaving a protective tube 19, 20 show a state in which removal of other equipment, filling concrete 24 in the space of the opening 17, 18 of the working chamber ceiling plate 15 and the working chamber 2 of the space at this stage Fill. Then, when removing the protective tube bodies 19 and 20, in the case of a sheet pile, it pulled out upwards, in the case of a corrugated pipe, it disassembled sequentially from the lower segment, and after the completion of the disassembly, the protective tube bodies 19 and 20 existed. The back space is filled with earth and sand. When the protective pipes 19 and 20 are buried and processed, the internal space of the pipes is filled with supplementary earth and sand.

  FIG. 4 shows the final process, in which the observation well 13 is buried simultaneously with the excavated soil 4c filled in the reinforced concrete housing 1 and the upper opening of the reinforced concrete housing 1 is closed with a concrete lid 25. An underground structure 1a such as a foundation of a structure constructed in this way and an underground facility is shown.

  When the underground structure 1a is constructed on the land to be purified by the above method, the soil is purified by constructing the upper reinforced concrete frame 1c as the reinforced concrete frame 1b is dug by excavation under the work room 2. The construction of the underground structure 1a can be performed in parallel, and the underground structure 1a can be completed substantially simultaneously with the completion of the removal and purification process of the contaminated soil 4b.

5 and 6 show the second embodiment. When the purpose of use of the land after purifying the VOC-contaminated soil is not decided and only for the purpose of purifying the contaminated soil by the VOC, the reinforced concrete frame 1b forming the work chamber 2 as shown in FIGS. Is constructed, and the reinforced concrete frame 1b is sunk by excavating the soil 4a under the working chamber 2 by the same excavation method as in the first embodiment. That is, since the construction of reinforced concrete building frame 1b does not perform the construction of the building frame corresponding to the upper reinforced concrete skeleton 1c embodiment 1, while sinking a reinforced concrete skeleton 1b, from the upper surface of the working chamber ceiling plate 15 to the ground surface 4 By refilling the excavated earth and sand 4c after the release of VOC into the inside surrounded by the outer shape of the reinforced concrete frame 1b over the range, the soil above the set reinforced concrete frame (caisson frame) 1b is purified. It becomes possible to return to the original state. FIG. 6 shows the final mode after performing the purification process.

  At the time of purification treatment of soil contaminated with VOC according to the second embodiment, the concrete frame 1b is set up while assembling a simple earth retaining wall 26 composed of a plurality of segments above the upper end 14 of the reinforced concrete frame 1b as shown in FIG. Go. Accordingly, the surrounding earth and sand wall does not collapse to the upper side of the set-up concrete frame 1b, and the excavated earth and sand from which the VOC has been released can be smoothly discharged to the upper side of the concrete frame 1b by the earth bucket 8. After the concrete frame 1b is set to the lowest layer of the VOC-contaminated soil, the retaining wall 26 is pulled up to the ground by dismantling or other means. Of course, it may be buried.

  As described above, according to the second embodiment, when the use and use of land after purification treatment of VOC-contaminated soil is undecided and the purpose is only to purify contaminated soil, only the reinforced concrete frame 1b forming the work chamber 2 is used. Then, without constructing the enclosure, the purified soil is backfilled on the enclosure, so that the land contaminated with VOC can be purified and restored to its original state.

[Action]
According to the method for purifying VOC-contaminated soil by the pneumatic caisson method of the present invention, the contaminated soil under the work room is removed by an excavator provided in the work room space provided at the bottom of the caisson housing constructed of reinforced concrete. The caisson housing can be set by excavating. Further, the excavator can be remotely operated from the ground, and can excavate soil contaminated with VOCs without entering a work room.

  In addition, VOC is discharged from the soil by agitating the soil contaminated with VOC excavated by an excavator in an unmanned working chamber and exposing it to the air, and it becomes a purification processing facility through a pipe connecting the working chamber and the ground purification processing facility. Air is supplied and purification is performed. The excavated soil from which the VOC has been discharged is loaded into an earth bucket, transported to the ground, and discharged to the upper side of the caisson housing forming the work room or the reinforced concrete housing connected to the caisson housing without being temporarily placed.

  In addition, by adjusting the pressure difference caused by the water pressure at the blade tip depth of the caisson blade fitting that works according to the groundwater level to slightly reduce the atmospheric pressure in the work chamber, The contaminated groundwater is submerged, and the water is sent to the ground purification facility through a pipe buried in the reinforced concrete frame by a submersible pump.

  If it is known in advance that the foundation of the structure and underground facilities will be constructed on the land to be cleaned by the above method, the reinforced concrete frame will be placed on the upper part of the reinforced concrete frame (caisson frame) that forms the work room. As a result, it becomes possible to carry out the purification process of contaminated soil and the construction of underground structures in parallel, and the purification of soil contaminated with VOCs and the construction of underground structures made of reinforced concrete have It becomes possible to construct in a shorter time than the method.

  If the purpose of use of the land to be purified is undecided and the purpose is only to purify contaminated soil, only the reinforced concrete frame that forms the work room is constructed, and the concrete frame is subsidized by excavation under the work room by an excavator Then, without constructing the concrete frame, the purified soil is backfilled on the concrete frame, so that the land contaminated with VOC can be purified and restored to its original state.

When an observation well is provided for regularly investigating the condition of the soil that has been reclaimed and backfilled, it becomes possible to construct the observation well as the work room is set up.

FIG. 3 is a longitudinal sectional view of the concrete caisson housing for purifying the soil contaminated with VOC according to the first embodiment. It is a side view showing an embodiment of ground VOC purification equipment. It is a longitudinal cross-sectional view of the process of removing the caisson subsidence equipment after the caisson housing is installed. It is the longitudinal cross-sectional view of the state which constructed | assembled the underground structure simultaneously with completion | finish of the purification | cleaning of the soil contaminated with VOC. FIG. 5 is a longitudinal cross-sectional view of a concrete caisson housing for purifying soil contaminated with VOCs according to a second embodiment. It is the longitudinal cross-sectional view of the state which backfilled the earth and sand by which the purification process was carried out simultaneously with the completion | finish of purification | cleaning of the soil contaminated with VOC.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reinforced concrete frame 1a Underground structure 1b Frame which forms work room 2 Work room 3 Excavator 4 Ground surface 4a Excavated ground 4b Soil contaminated with VOC 4c Purified excavated soil 4d Stirred excavated soil 5 In work room Submerged groundwater 5a Submersible pump 5b VOC-contaminated water supply pipe 6 VOC-contaminated gas supply pipe 7 Blade fitting 8 Earth bucket 9 Air supply equipment 10 Person entrance / exit system 10a Manlock 10b Material lock 11 Material entry / exit room system and excavating soil unloading system 12 purification treatment equipment 12a underground water tank 12b aeration tank 12c charcoal layer 12d treating tank 12e sediment pits 12f heater 13 borehole 14 upper 15 working chamber ceiling plate 16 the peripheral wall portion 17 opening 18 opening 19 protection Tube 20 Protective tube 21 Sediment 22 Soil Groundwater 22a groundwater 23 wells 24 filled concrete 25 concrete lid 26 braced wall

Claims (9)

Using pneumatic caisson method as drilling method of contaminated soil in VOC, working chamber ceiling plate outer circumferential peripheral wall portion provided on the reinforced concrete skeleton of the working chamber for forming consisting comprises a blade cap was at the lower end of (caisson building frame) An excavator that can be remotely operated from the ground is installed in the work room of this factory, and the excavator excavates the contaminated soil under the caisson, agitates it, and exposes it to the air to release VOC from the soil. while the purification treatment led to purification treatment facility installed gas and contaminated water on the ground, the excavated soil which emit VOC, characterized in that earth removal on the upper side of the working chamber ceiling plate with the subsidence of the caisson skeleton contaminated soil Purification treatment method.   2. The method for purifying contaminated soil according to claim 1, wherein the VOC released by agitating the contaminated soil and exposing it to air is sent to the purification facility through a pipe connecting the caisson work room and the purification facility installed on the ground. And a purification treatment method for contaminated soil, wherein the purification treatment is performed. In the purification method of processing contaminated soil according to claim 1, the pressure difference generated by the cutting edge depth of water pressure caisson blade die which act by pressure and groundwater level of the working chamber, pressure in the working chamber is reduced By adjusting as described above, groundwater contaminated with VOCs is submerged in the work chamber, and water is sent to the purification equipment through a pipe connecting the caisson work room and the purification equipment installed on the ground by a submersible pump to perform purification treatment. The method for purifying contaminated soil, characterized in that the pollutant is collected without being dissipated and purified. In the purification treatment method of the contaminated soil according to any one of claims 1 to 3, it is known in advance that an underground structure such as a foundation of a structure or an underground facility is constructed as a use application of the land to be purified. In this case , the upper reinforced concrete frame is constructed at the upper end of the concrete frame for forming the work room by excavation under the caisson, and the purified excavated soil is discharged inside the upper reinforced concrete frame. A method for purifying contaminated soil, comprising performing soil purification treatment and construction of an underground structure in parallel. In the purification treatment method of the contaminated soil according to any one of claims 1 to 3, in the implementation only for the purification of land where the use of the purified land is undecided, only the reinforced concrete frame forming the work room is used. and sinking with the drilling, characterized in that the state of soil and purifying processes after sinking the concrete skeleton by backfilling the excavation soil was cleaned on the upper side of the working chamber ceiling plate by sinking of the concrete skeleton contaminated soil Purification treatment method. In the purification processing method of the contaminated soil of any one of Claims 1-4 , the observation well for investigating the state of the backfilled soil regularly is constructed with the subsidence of the reinforced concrete frame. A method for purifying contaminated soil.   In the purification method of the contaminated soil of any one of Claims 1-3 and 5, the observation well for investigating the state of the backfilled soil regularly is constructed with the sunk of the reinforced concrete frame. A method for purifying contaminated soil, characterized by being followed.   Reinforced concrete frame which is a structure constructed as an underground structure such as a foundation or an underground facility by the contaminated soil purification treatment method according to any one of claims 1 to 4 and claim 6 and forms a work room An underground structure in which an upper reinforced concrete frame is continuously connected to the upper part of the reinforced concrete, and excavated soil after VOC is discharged is discharged into the upper reinforced concrete frame. An underground structure in which the method for purifying contaminated soil according to any one of claims 1 to 3 and claims 5 and 7 is implemented for land purification only, with no land use yet, and a work room is formed. Reinforced precursor to the are sinking to the deepest layer of VOC contaminated soil, the inner said reinforced concrete skeleton from the top surface of the working chamber ceiling plate after sinking over a range up to the ground, and is surrounded by the outer shape of the caissons skeleton An underground structure characterized by being backfilled with excavated soil after the VOC has been released.

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