JP2005296824A - Permeable ground water cleaning wall - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permeable ground water cleaning wall capable of being constructed even in a steep slope site, a site allowing only a relatively narrow work space, a site having a height restriction in the upper air, or the like. <P>SOLUTION: The permeable ground water cleaning wall 1 comprises a permeable hollow area 10 disposed so as to cross in a flow direction of contaminated ground water 2 in the ground of the lower stream side area of the contaminated ground water 2 and a filler filled into the hollow area 10, and at least part of the filler comprises a permeable cleaning agent 21 for cleaning the contaminated ground water 2 permeating through. The hollow area 10 is constructed by an earth retaining member 11 having a plurality of water passage holes 12 on the side face and split at least in a vertical direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a permeable groundwater purification wall that enables purification of contaminated groundwater by disposing it in the basin of contaminated groundwater.

  Groundwater may be polluted by the penetration of hazardous substances and factory waste liquids from waste disposal sites and illegal dumping waste. The groundwater contaminated in this way (hereinafter referred to as “contaminated groundwater”) is diffused by the flow of the groundwater, and thus adversely affects the environment in the surrounding area.

  Conventionally, a permeable groundwater purification wall has been adopted as one of countermeasures for preventing the diffusion of such contaminated groundwater. This permeable groundwater purification wall is constructed by continuously arranging a permeable purification agent in the downstream basin of the contaminated groundwater so as to intersect the direction of flow of the contaminated groundwater. And in the process in which contaminated groundwater passes this permeable groundwater purification wall, it becomes possible to remove the contaminant contained in the contaminated groundwater.

  The construction of these permeable groundwater purification walls is generally done by filling the groove excavated by trench excavation etc. with a cleaning agent, or by placing casing pipes to replace the earth and sand inside the trench. After that, it has been carried out by a construction method for pulling out the casing pipe. However, the permeable groundwater purification wall constructed in this way is constructed with a new permeable groundwater purification wall because it is difficult to replace the purification agent when the function of the purification agent is reduced due to long-term use. It was necessary and time-consuming, and there was a problem that a separate site was required.

Therefore, in Patent Document 1, a steel pipe sheet pile having a plurality of holes formed on the side portion and having permeability is continuously arranged so as to intersect the direction of flow of contaminated groundwater, and the inside thereof is filled with a purifier. A sheet pile wall (permeable groundwater purification wall) for groundwater purification is described. The groundwater purification sheet pile wall has a configuration in which a purification agent is disposed inside a steel pipe sheet pile having permeability, so that the internal purification agent can be taken out, and the function of the purification agent whose function has been deteriorated due to long-term use. The replacement work can be easily performed.
JP 2002-294692 A ([0032]-[0057], FIGS. 1-3)

  However, when building a permeable groundwater purification wall on the site of a factory, etc., there are many cases where construction on steep slopes or narrow sites is often required. In some cases, construction could not be performed because the heavy machinery required for the construction could not enter. In particular, in the construction method constructed with steel pipe sheet piles, etc., it is necessary to press-fit or drive in a steel pipe sheet pile having a length equivalent to the depth of the permeable groundwater purification wall. It was difficult to squeeze, and in the worst case, the construction was impossible.

  The present invention is intended to solve the above-mentioned problems, and it is possible to perform construction at a steep slope, a construction place where only a relatively narrow work space can be secured, a construction place where the height is limited, and the like. The objective is to propose a permeable groundwater purification wall.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a permeable hollow region disposed in the ground of the downstream basin of the contaminated groundwater so as to intersect the direction of flow of the contaminated groundwater, A permeable groundwater purification wall made of a permeable purification agent that purifies the contaminated groundwater into which at least a part of the filler has permeated. The hollow region has a plurality of water permeable holes on the side surface and is composed of an assembly-type earth retaining member divided at least in the vertical direction.

  Since such a permeable groundwater purification wall is constructed using an assembly-type earth retaining member divided in the vertical direction, it is necessary to press-fit or drive in a soil retaining member having a length substantially the same as the depth of the permeable groundwater purification wall. There is no. In addition, since it is not necessary to place heavy machinery required for the construction of the earth retaining members, construction is possible even when only a narrow work space such as in a factory site can be secured or when it is difficult to enter heavy machinery due to steep slopes. is there. In addition, since the earth retaining member having a plurality of water permeable holes on the side surface is used as a part of the permeable groundwater purification wall, even if the function of the purification agent is deteriorated due to long-term use, the replacement work of the purification agent is performed. It can be easily performed.

  In addition, if the hollow region has a configuration in which a plurality of hollow pile bodies (hereinafter simply referred to as “pile bodies”) are arranged in a row, it corresponds to the flow rate, flow rate, and contamination concentration of contaminated groundwater. It is preferable because it is possible to change the filler for each pile body and to adjust the permeability coefficient, blending, and the like of the permeable purifier. Moreover, even if the purification function of the purification agent is deteriorated due to long-term use, if the purification agent is replaced for each pile body, the work can be performed without stopping the flow of contaminated groundwater.

  Moreover, if the assembly-type earth retaining member is a liner plate, the earth retaining member can be transported by human power, and the assembly work is facilitated. That is, this permeable groundwater purification wall is suitable because it can be easily constructed by human power without requiring heavy machinery.

  In addition, if the permeable groundwater purification wall has a water-impervious part, the flow direction of the contaminated groundwater does not change inside the permeable groundwater purification wall, and the permeable groundwater purification wall By construction, it is preferable that the downstream groundwater basin does not change.

  According to the present invention, it is possible to easily construct a permeable groundwater purification wall even in a construction site having various restrictions such as a steep slope, a narrow site, or a construction site having a height restriction in the sky.

  Preferred embodiments of the present invention will be described with reference to the drawings. In the description, the same reference numerals are used for the same elements, and duplicate descriptions are omitted.

FIG. 1 is a perspective view showing an overall outline of a permeable groundwater purification wall 1 according to the present embodiment. FIG. 2 is a side sectional view of the permeable groundwater purification wall 1. 3 is an enlarged view of a part of the permeable groundwater purification wall 1 shown in FIG. 1. FIG. 3A is a plan sectional view, and FIG. 3B is a front sectional view.
Here, the left and right in the description are determined by looking at the upstream direction from the downstream side with reference to the direction of groundwater flow.

  In the present embodiment, as shown in FIGS. 1 and 2, a case where a permeable groundwater purification wall 1 is constructed on a slope in a factory site will be described.

  As shown in FIG. 1, the permeable groundwater purification wall 1 is located downstream of contaminated groundwater 2 that flows down and contains pollutants by passing through a pollution source that has infiltrated factory waste liquid or the like and has accumulated in the ground. The cross-sectional shape continuously arranged in the direction of blocking the flow direction of the contaminated groundwater 2 in the basin is constituted by a plurality of oval pile bodies 10 (hollow regions). As for each pile body 10, the outer shell is comprised by the several liner plate 11, and the lower end is inserted even in the position deeper than the impermeable layer line RL (refer FIG. 2).

Here, each pile body 10 is configured by stacking up and down oval-shaped rings formed by joining four liner plates 11 together. The liner plate 11 is connected at four joints of the joints t1 and t1 on the left and right sides of the pile body 10 and the joints t2 and t2 at the center in the upstream and downstream sides of the contaminated groundwater 2. (See FIG. 3A).
Further, the pile body 10 includes a purification pile 10 a that transmits the contaminated groundwater 2 and a water-proof pile 10 b that shields the contaminated groundwater 2. The purification pile 10a is composed of a perforated liner 11a having water-permeable holes 12 on both upstream and downstream sides thereof, and the water-impervious pile 10b is composed of a non-porous liner 11b having no water-permeable holes 12. ing. In addition, the permeable groundwater purification wall 1 of this Embodiment is comprised by arrange | positioning these purification piles 10a and the impermeable pile 10b alternately.

  The contaminated groundwater 2 passes through the purification pile 10a of the permeable groundwater purification wall 1 so that the contained contaminants are removed and the purified groundwater 3 is obtained.

  As shown in FIG. 2, the purification pile 10 a has a permeable purification agent (hereinafter simply referred to as “permeability”) composed of a mixture of concrete 20, a metal reducing agent such as iron powder, an adsorbent such as activated carbon, and crushed stone. It may be referred to as a “cleaning agent”) 21 and high quality generated soil 22 generated by excavation of the pile body 10. Here, the permeable purification material 21 secures a predetermined gap by mixing crushed stones, maintains a predetermined water permeability in the purification pile 10a, and is an amount of an expensive purification material such as iron powder or activated carbon. Can be reduced. In addition, the mixing | blending of each material which comprises the permeable purification material 21 shall be adjusted according to the flow volume and flow velocity of polluted groundwater 2, a pollutant, its density | concentration, etc. Further, the concrete 20 placed in the purification pile 10a has a cross section by a bottom slab concrete 20a placed on the entire bottom surface of the purification pile 10a and a side concrete 20b placed on the left and right sides of the purification pile 10a. The shape is U-shaped (see FIG. 3B).

  As shown in FIG. 2, the bottom slab concrete 20a is placed from the lower end of the purification pile 10a to a position slightly higher than the impermeable layer line RL, and the covering soil by the generated soil 22 is from the upper end of the purification pile 10a to the groundwater level. The operation is performed up to a position slightly higher than the line WL. As shown in FIGS. 3 (a) and 3 (b), side concrete 20b is placed on the left and right ends between the upper end of the bottom slab concrete 20a and the lower end of the generated soil 22, and the left and right side portions are arranged. A permeable purification agent 21 is filled between the concrete 20b.

  On the other hand, as shown in FIGS. 3 (a) and 3 (b), the impermeable pile 10b is filled with concrete 20 from the lower end of the impermeable pile 10b to a position slightly higher than the groundwater level line WL (see FIG. 2). From the upper end of the concrete 20 to the upper end of the water-impervious pile 10b, a cover soil composed of the generated soil 22 is formed.

Further, on the slightly downstream side from the center with respect to the direction of groundwater flow of each pile body 10, a water-stop seal 23 made of water-expandable rubber is formed in a U shape along the inner surface of the liner plate 11 and the bottom surface of the pile body 10. It is arranged.
Furthermore, as shown in FIG. 3A, the joint between the purification pile 10 a and the water-impervious pile 10 b is joined via a water stop plate 30 made of a rubber plate, and on the upstream side of the water stop plate 30. Is provided with water-stopping concrete 31.

Next, the construction method of the permeable groundwater purification wall 1 of this Embodiment is demonstrated using FIG.4 and FIG.5.
Here, Fig.4 (a)-(f) is sectional drawing which showed the construction method of the purification pile 10a for every construction step. 5 (a) is an exploded perspective view showing a joint portion between adjacent pile bodies 10, FIG. 5 (b) is a plan view thereof, and FIG. 5 (c) is an installation state of the water stop plate 30. It is sectional drawing shown.

  First, excavation is performed at a predetermined position where the permeable groundwater purification wall 1 is constructed, slightly deeper than the height of one stage of the liner plate 11 in accordance with the shape of the pile body 10 (see FIG. 4A).

  When excavation at a predetermined depth is completed, a single oval ring is quickly assembled with the liner plate 11 and the opening surface is closed (see FIG. 4B). Here, when the liner plate 11 is assembled, a water stop plate 30 to be described later is sandwiched between the upstream and downstream liner plates 11 and 11 at the left and right joints t1 of the pile body 10 in advance. Further, although the depth of excavation is set to be slightly deeper than the height of one stage of the liner plate 11, the liner plate 11 may be assembled in a plurality of stages by excavating deeply according to the condition of the natural ground.

  Subsequently, the excavation work and the assembly work of the liner plate 11 are repeated until the lower end of the pile body 10 is deeper than the impermeable layer line RL (see FIG. 4C). The excavation work is performed using a small construction machine capable of working inside the pile body 10, or is performed manually. Further, the assembly work of the liner plate 11 may be performed manually. Here, at the time of construction, inflow of contaminated groundwater 2 to the construction site is prevented by a known groundwater level lowering method or the like.

  When excavation work and assembly work of the liner plate 11 are completed to a predetermined depth, the concrete 20 is placed. The placement of the concrete 20 includes a bottom slab concrete 20a that is placed in the entire cross-sectional area of the pile body 10 to a position higher than the impermeable layer line RL, and a pile body from the upper end of the bottom slab concrete 20a to a position higher than the groundwater level line WL. The side concrete 20b to be placed on the left and right side portions of 10 is placed in two stages. The concrete 20 is formed into a U-shaped cross section by the bottom slab concrete 20a and the left and right side concretes 20b (see FIG. 4D). Under the present circumstances, the water stop seal 23 is previously installed so that the outer periphery of the concrete 20 may be covered slightly downstream from the center of the flow direction direction of the contaminated groundwater 2 of the pile body 10.

  When the placement of the concrete 20 is completed, the concave portion of the concrete 20 is filled with the permeable purification agent 21. At this time, the upper end of the permeable purification agent 21 is filled so as to be the same height as the upper end of the side concrete 20b (see FIG. 4E).

  When the filling of the permeable purifier 21 is completed, the soil is covered with the generated soil 22 generated by excavation of the pile body 10 up to the upper end of the pile body 10 (see FIG. 4F).

Then, the same work is repeated and the adjacent pile body 10 is constructed. And the permeable groundwater purification wall 1 is constructed | assembled by repeating construction of the pile body 10 several times.
Here, when constructing the impermeable pile 10b, the permeable purifier 21 is not filled, and the concrete 20 is filled up to a position higher than the groundwater level line WL inside the pile body 10.

In addition, joining of the pile bodies 10 is performed via the water stop board 30 as shown to Fig.5 (a)-(c).
When the liner plate 11 is assembled in the liner plate 11, the adjacent pile bodies 10, 10 have the left and right end portions of the same single waterproof plate 30 at the respective joint portions t 1. (See FIGS. 5A and 5B). Here, as shown in FIG. 5C, the water stop plate 30 is wider than the liner plate 11 and protrudes downward from the lower end of the liner plate 11 when the liner plate 11 is assembled. It is arranged. Then, when assembling the liner plate 11 at the next stage, the liner plate 11 is arranged so that the lower end portion of the existing water stop plate 30 a and the upper end portion of the new water stop plate 30 b overlap each other, and are sandwiched by the liner plate 11.

  Moreover, the water stop concrete 31 is laid in the surplus digging part 32 of the upstream of the water stop board 30 in the junction part of the pile body 10 (refer FIG.5 (b)). When placing the still water concrete 31, the formwork 31 a is installed so that the liner plate 11 and the triangle are formed in the surplus digging portion 32 of the joint, and the concrete is piled along the surplus digging portion 32. Do not go around around 10.

  As described above, the permeable groundwater purification wall 1 according to the present embodiment has a structure in which the permeable purification agent 21 is filled in the interior of the soiled wall with the liner plate 11, so that the permeable purification can be achieved by using it for a long time. Even when the purification function of the agent 21 is lowered, it is possible to excavate and remove only the permeable purification agent 21 and newly fill it. Therefore, it is possible to construct the permeable groundwater purification wall 1 that can be used for a long period of time while maintaining the purification function.

  Moreover, since the said permeable groundwater purification | cleaning wall 1 has arrange | positioned the impermeable pile 10a alternately with the impermeable pile 10b filled with the concrete 20, it can also obtain the slope suppression effect by the impermeable pile 10b. Become.

In addition, by using the liner plate 11 that can be carried by human power and easy to assemble, the permeable groundwater purification wall 1 can be used for narrow construction places where construction machines cannot enter and construction on steep slopes. Can be constructed.
Moreover, since the pile body 10 is constructed by the so-called reverse winding method, which is excavated while gradually assembling the liner plate 11, there is no need to place a retaining member having a length substantially the same as the depth of the permeable groundwater purification wall such as a casing. In addition to requiring a large construction machine, it is possible to construct a construction site where the sky is limited.

Moreover, the pile body 10 is formed by the oval liner plate 11, and the purifying agent 21 is arranged in a square shape at the center in the left-right direction of the pile body 10, so that it passes through the permeable groundwater purification wall 1. The contaminated groundwater 2 to be purified can be purified uniformly by a purification body having a certain thickness compared to a permeable groundwater purification wall made of a conventional circular purification pile.
Further, by adjusting the combination and shape of the liner plate 11, it is possible to form the permeable groundwater purification wall 1 having a thickness necessary for purification as appropriate.

In addition, the inclusion of crushed stones creates a relatively large gap, which prevents clogging of the gap in the permeable purifier due to calcium salts, etc. generated by corrosion of iron powder, Can be maintained.
Moreover, since it was set as the structure which arrange | positions the permeable purification agent 21 in the predetermined pile body 10 among the permeable groundwater purification walls 1 comprised by the aggregate | assembly of the pile body 10, the usage-amount of an expensive purification agent is minimized. Therefore, it is possible to construct a permeable groundwater purification wall 1 excellent in economic efficiency.

Further, since the soil is covered with the high-quality generated soil 22 generated by excavation of the pile body 10, it is possible to reduce the excavated residual soil and reduce the cost for disposal of the residual soil.
Moreover, since each pile body 10 is provided with a water-stop seal 23 along the inner surface of the liner plate and the bottom surface of the pile body 10 slightly downstream from the center with respect to the flow direction of groundwater, Even when a gap is formed between the concrete 20 and the liner plate 11 due to the contraction of the water 20, the contaminated groundwater 2 flows down without being purified because it is stopped by the expanded water seal 23. Can be suppressed.
Further, since the bottom slab concrete 20a is placed at the bottom of the purification pile 10a, it is suppressed that earth and sand and the permeable purification agent 21 are mixed and the purification function is deteriorated due to the occurrence of boiling or the like. Is done.

As mentioned above, although the example of suitable embodiment was demonstrated about this invention, this invention is not limited to the said embodiment, A design change is possible suitably in the range which does not deviate from the meaning of this invention.
For example, in the above embodiment, the permeable groundwater purification wall is formed by an assembly of a plurality of pile bodies, but may be constituted by a so-called wall-shaped continuous underground wall having a rectangular parallelepiped shape, The configuration is not limited.
In the above embodiment, the purification piles and the impermeable piles are alternately arranged. However, only the purification piles may be arranged, and the arrangement considers the flow rate of contaminated groundwater, the contamination concentration, and the like. Can be set as appropriate.

In the above-described embodiment, the construction of the impervious pile and the construction of placing the concrete on the side of the purification pile are used, but soil cement, bentonite improved soil, etc. may be used, which is impervious and contaminated. The material is not limited as long as the penetration of groundwater can be prevented.
In addition, when concrete was placed in the purification pile, the bottom slab concrete and the side concrete were placed in two stages. However, the present invention is not limited to this. It may be placed in.

In the above embodiment, the construction of the permeable groundwater purification wall is performed by excavation using a retaining member made of a liner plate. It may be constructed by a method of performing and placing an assembly-type earth retaining material, and the construction method is not limited.
In the above embodiment, the oval liner plate is used as the plurality of purification piles constituting the permeable groundwater purification wall. However, a liner plate that forms a rectangular or circular cross section is used. The cross-sectional shape of each purification pile is not limited. Moreover, the shape dimension of each liner plate is not limited.

In addition, although the water-permeable holes are formed in the liner plate at the position corresponding to the permeable purifier, the contaminated groundwater may be permeated using the gap between the joint portions of the liner plate depending on the flow rate of the contaminated groundwater. In addition, the configuration of the permeated portion of the contaminated groundwater is not limited.
Moreover, it goes without saying that a support work or the like may be appropriately installed inside the pile body according to the situation of the natural ground.

In the above-described embodiment, a mixture of iron powder, activated carbon, and crushed stone is used as the permeation purifier. For example, a mixture of either iron powder or activated carbon and crushed stone may be used. The structure of the permeable purifier is not limited as long as it has a structure corresponding to the pollutant contained in the contaminated groundwater. Moreover, it is not limited to iron powder and activated carbon, and it goes without saying that other materials having a purification function may be used depending on the contaminant.
Moreover, if the predetermined | prescribed permeability | transmittance of a permeability | transmittance purifying agent can be maintained, it will not be limited to crushed stone, For example, you may use silica sand etc.
In addition, as the soil covering material, high-quality soil generated from excavation of the pile body was used, but it is not limited to this, and it is possible to prevent infiltration of excessive surface water. If so, the material is not limited.

It is a perspective view which shows the outline | summary of the whole of a permeable groundwater purification wall. It is a sectional side view of the permeable groundwater purification wall of FIG. It is the figure which expanded and showed a part of permeable groundwater purification wall of FIG. 1, (a) is a plane sectional view, (b) is a front sectional view. It is sectional drawing which shows each step regarding the construction method of the permeable groundwater purification wall by this invention, (a) is an excavation situation, (b) is a liner plate installation situation, (c) is a runner plate assembly completion situation, (d). Is a concrete placement situation, (e) is a permeability purification agent filling situation, and (f) is a covering soil filling situation. It is a figure which shows the detail of the junction part of adjacent purification | cleaning piles, (a) is a disassembled perspective view, (b) is an enlarged plan view, (c) is an expanded sectional view.

Explanation of symbols

1 Permeable groundwater purification wall 2 Contaminated groundwater 3 Purified groundwater 10 Pile body (hollow area)
10a Purification pile 10b Impervious pile 11 Liner plate (earth retaining member)
12 Water permeability 20 Concrete (filler)
21 Permeability purification agent (filler)
22 Generated soil (filler)

Claims (4)

A permeable hollow region disposed in the ground of the downstream watershed of the contaminated groundwater so as to intersect the direction of flow of the contaminated groundwater;
A filler filled in the hollow region, and
A permeable groundwater purification wall comprising a permeable purification agent that purifies the contaminated groundwater into which at least part of the filler has permeated;
The permeable groundwater purification wall according to claim 1, wherein the hollow region has a plurality of water permeable holes on a side surface and is composed of an assembly-type earth retaining member divided at least in the vertical direction.   The permeable groundwater purification wall according to claim 1, wherein the hollow region is formed by arranging a plurality of hollow pile bodies in a row.   The permeable groundwater purification wall according to claim 1 or 2, wherein the assembly-type earth retaining member is a liner plate.   The permeable groundwater purification wall according to any one of claims 1 to 3, wherein the permeable groundwater purification wall has a water shielding property at a part thereof.

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