JP7205792B2 - ground improvement structure - Google Patents

Description

The present invention relates to a ground improvement structure.

A grid-like ground improvement body formed in a grid-like shape in plan view is known (see, for example, Patent Document 1).

Japanese Patent No. 5919429

By the way, as a method for remediation of contaminated ground, an injection solution containing an activator that proliferates and activates microorganisms that decompose pollutants in the contaminated ground (hereinafter referred to as "degrading microorganisms") is poured from an injection well into the contaminated ground. It is known how to inject. In this type of purification method, an impermeable wall surrounding the contaminated ground is constructed in the ground in order to suppress the diffusion of contaminants.

Here, it is conceivable to use the above-mentioned grid-like soil improvement body as the impermeable wall.

However, in the grid-like soil improvement body, the ground is divided into a plurality of areas (hereinafter referred to as "divided areas"). Therefore, for example, if the contaminated ground extends over a plurality of partitioned areas, an injection well must be provided in each partitioned area, which may increase construction costs.

In addition, for example, when the contaminated ground is deep in the ground, forming a grid-like soil improvement body so as to reach the contaminated ground increases the amount of construction of the grid-like ground improvement body, which may increase the construction cost.

An object of the present invention is to reduce construction costs in consideration of the above facts.

The ground improvement structure according to the first aspect includes a ground improvement body having a partition wall portion that partitions the ground into a plurality of partitioned areas, an injection well provided in the partitioned area, and one of the partitions provided with the injection well a water passage part provided in the partition wall part between one area and the other partition area and allowing groundwater to pass through.

According to the ground improvement structure according to the first aspect, the ground improvement body has partition walls that partition the ground into a plurality of partitioned areas. Injection wells are also provided in the partitioned areas.

Here, if there is no water passage part in the partition wall part between one partition area where the injection well is provided and another partition area, the injection liquid is injected into the one partition area and the other partition area. In order to do so, it is necessary to provide injection wells in one partitioned area and in the other partitioned area, respectively.

On the other hand, in this aspect, the partition wall portion between one partition area in which the injection well is provided and another partition area is provided with a water passage portion for passing groundwater. As a result, the injection liquid injected from the injection well into one partitioned area is supplied to the other partitioned area through the water passage. Therefore, in this embodiment, injection wells in other partitioned regions can be omitted. Therefore, in this aspect, the number of injection wells can be reduced.

A ground improvement structure according to a second aspect comprises a pumping well provided in the other partitioned area in the ground improvement structure according to the first aspect.

According to the ground improvement structure according to the second aspect, pumping wells are provided in other partitioned areas. From this pumping well, groundwater in other subdivisions containing contaminants is pumped.

Here, a partition wall portion between one partitioned region in which the injection well is provided and another partitioned region is provided with a water passage portion for passing groundwater. As a result, the groundwater in one partitioned area flows into the other partitioned area through the water passage. Therefore, it is possible to pump up groundwater in one partitioned area from pumping wells provided in other partitioned areas. Therefore, in this aspect, the number of pumping wells can also be reduced.

A ground improvement structure according to a third aspect comprises a soil improvement body that divides the ground into a small division area, a large division area that is wider than the small division area, and an injection well provided in the large division area.

According to the ground improvement structure according to the third aspect, the ground improvement body divides the ground into a small division area and a large division area wider than the small division area. Injection wells are also provided in the large subregions.

Here, for example, when all the divided areas of the ground have the same size, the contaminated ground tends to extend over a plurality of divided areas. In this case, the number of injection wells increases because it is necessary to provide injection wells in a plurality of partitioned areas that span the contaminated ground.

On the other hand, in this aspect, by forming large division areas according to the size of the contaminated ground, it is possible to prevent the contaminated ground from extending over a plurality of division areas. Therefore, in this aspect, the number of injection wells can be reduced as compared with the case where all the partitioned regions have the same size.

A ground improvement structure according to a fourth aspect is the ground improvement structure according to the third aspect, and includes a pumping well provided in the large division area.

According to the ground improvement structure according to the fourth aspect, a pumping well is provided in the large division area. From this pumping well, a large area of groundwater containing contaminants is pumped up.

Therefore, in this aspect, by forming large division areas according to the extent of the contaminated ground, not only the number of injection wells but also the number of pumping wells can be reduced.

The ground improvement structure according to the fifth aspect includes a ground improvement body that divides the ground into a plurality of divided areas, and a part of the ground improvement body that is formed by extending downward to surround the ground below the ground improvement body. An extension and an injection well provided in the ground surrounded by the extension.

According to the ground improvement structure according to the fifth aspect, the ground improvement body partitions the ground into a plurality of partitioned areas. Further, the soil improvement body is provided with an extension. The extension is formed by extending a portion of the soil improvement body downward. This extension of the soil improvement body, for example, by enclosing the contaminated ground beneath the soil improvement body, inhibits the diffusion of pollutant-laden groundwater.

Also, an injection well is provided in the ground surrounded by the extension. From this injection well, for example, an injection liquid containing an active agent or the like can be injected into the contaminated ground.

Thus, in this aspect, by surrounding the ground below the soil improvement body with the extension of the soil improvement body, compared to the case where the impermeable wall is formed below the soil improvement body separately from the ground improvement body , the construction cost can be reduced.

As explained above, according to the ground improvement structure according to the present invention, construction costs can be reduced.

1-1 line cross-sectional view of FIG. 2 showing the ground to which the ground improvement structure according to the first embodiment is applied. FIG. 2 is a plan sectional view showing the grid-like soil improvement body shown in FIG. 1; FIG. 2 is a vertical cross-sectional view showing a partition wall portion provided with a water passage portion shown in FIG. 1; (A) is a plan sectional view corresponding to FIG. 2 showing a first modification of the ground improvement structure according to the first embodiment, and (B) is a second modification of the ground improvement structure according to the first embodiment FIG. 3 is a plan sectional view corresponding to FIG. 2 showing an example; (A) is a plan sectional view corresponding to FIG. 2 showing a third modification of the ground improvement structure according to the first embodiment, and (B) is a fourth modification of the ground improvement structure according to the first embodiment FIG. 3 is a plan sectional view corresponding to FIG. 2 showing an example; (A) is a flat cross-sectional view corresponding to FIG. 2 showing a grid-like soil improvement body of the ground improvement structure according to the second embodiment, and (B) is a modification of the ground improvement structure according to the second embodiment FIG. 3 is a plan cross-sectional view corresponding to FIG. 2 showing . It is a cross-sectional view along line 7-7 in FIG. 8 showing the ground to which the ground improvement structure according to the third embodiment is applied. FIG. 8 is a plan sectional view showing the grid-like ground improvement body shown in FIG. 7; It is a cross-sectional view along line 9-9 of FIG. 10 showing the ground to which the modification of the soil improvement structure according to the third embodiment is applied. FIG. 10 is a cross-sectional plan view showing the grid-like ground improvement body shown in FIG. 9;

(First embodiment)
First, the first embodiment will be described.

(ground)
FIG. 1 shows a ground 10 to which a ground improvement structure 20 and an underground soil remediation system 40 according to the first embodiment are applied, and a structure 12 constructed on the ground 10. As shown in FIG. The ground 10 has, as an example, a non-liquefaction layer 10A and a liquefaction layer 10B deposited on the non-liquefaction layer 10A. The arrow F shown in each figure indicates the flow of groundwater.

The liquefaction layer 10B includes sandy soil, and is highly likely to liquefy when an earthquake of a predetermined scale or more occurs. Also, the liquefaction layer 10B is an aquifer with a higher water permeability than the non-liquefaction layer 10A, and groundwater flows easily. On the other hand, the non-liquefied layer 10A is a hardly permeable layer having lower water permeability than the liquefied layer 10B, and is less likely to be liquefied.

The liquefaction layer 10B has contaminated ground 10P containing contaminants such as VOCs (volatile organic compounds). Contaminants include, for example, organic compounds (toluene and xylene contained in paints, printing inks, adhesives, detergents, gasoline, thinners, etc., tetrachlorethylene, trichlorethylene, cis-1,2-dichloroethylene, chloroethylene (vinyl chloride volatile organic compounds such as monomers), heavy metal compounds, inorganic compounds, oils, and the like.

In addition, the ground improvement structure 20 and the underground soil purification system 40 according to the present embodiment are applicable not only to the ground 10 described above, but also to various grounds in which the non-liquefaction layer 10A does not exist, for example.

(Soil improvement structure)
The soil improvement structure 20 comprises a grid soil improvement body 22 , an injection well 14 and a pumping well 16 . The grid-like ground improvement body 22 suppresses the liquefaction of the liquefaction layer 10B during an earthquake and also suppresses the diffusion of groundwater containing contaminants. This grid-like ground improvement body 22 is formed in the liquefaction layer 10B with, for example, a cement-based solidifying material.

In this embodiment, the lower end of the grid-like ground improvement body 22 reaches the non-liquefaction layer 10A, but the bottom end of the grid-like ground improvement body 22 does not reach the non-liquefaction layer 10A. Also good. Also, the grid-like ground improvement body 22 is an example of a ground improvement body.

As shown in FIG. 2, the grid-like ground improvement body 22 is formed in a grid-like shape in plan view. By imparting shear rigidity to the liquefaction layer 10B by the grid-like ground improvement body 22, liquefaction of the liquefaction layer 10B is suppressed.

Specifically, the grid-like ground improvement body 22 has an outer peripheral wall portion 24 and a plurality of partition wall portions 26 . The outer peripheral wall portion 24 is formed in a rectangular frame shape in plan view, and surrounds the ground 10 . Note that the arrow X direction and the arrow Y direction shown in FIG. 2 indicate two horizontal directions orthogonal to each other.

The partition wall portion 26 includes a plurality of partition wall portions 26A arranged along the arrow Y direction and a plurality of partition wall portions 26B arranged along the arrow X direction. The plurality of partition wall portions 26A are arranged at intervals in the arrow X direction. Moreover, the plurality of partition wall portions 26B are arranged at intervals in the arrow Y direction. The plurality of partition wall portions 26A and partition wall portions 26B are connected in a grid pattern in plan view. These partition walls 26A and 26B partition the inner region (liquefaction layer 10B) of the outer peripheral wall 24 into a plurality of regions (hereinafter referred to as “partition regions”) R. As shown in FIG. Note that the partition wall portions 26A and 26B are collectively referred to as the partition wall portion 26 below.

Here, in the present embodiment, the contaminated ground 10P straddles one divided region R1 and the other divided region R2 among the plurality of divided regions R. As shown in FIG. An injection well 14 is provided in one partitioned region R1. On the other hand, a pumping well 16 is provided in another partitioned region R2.

A partition wall portion 26S between one partition region R1 and another partition region R2 is provided with a plurality of water passage portions W through which groundwater passes. Note that the partition wall portion 26S is an example of a partition wall portion between one partition region R1 and another partition region R2.

As shown in FIG. 3, the water passage portion W is an unimproved ground portion partially provided in the partition wall portion 26S. Ground improvement is not performed in this water-conducting section W. That is, in the water passage W, no solidifying material such as a cement-based solidifying material is injected into the ground 10 . Thereby, in the water passage portion W, groundwater can flow. This water passage W is constructed by, for example, the following method.

That is, the partition wall portion 26S of the present embodiment has a plurality of columnar improved bodies 28A and 28B that are continuous in a wall shape. 28 A of columnar improvement bodies do not contain the water-conducting part W. As shown in FIG. This columnar improved body 28A is constructed by a mechanical stirring construction method. Specifically, the columnar improvement body 28A excavates the ground 10 while injecting a solidifying material such as a cement-based solidifying material from the tip of an excavation auger (not shown), and agitates and mixes the excavated soil and the solidifying material. is created.

On the other hand, the columnar improved body 28B includes a water-conducting portion W. As shown in FIG. This columnar improved body 28B is constructed by a high-pressure injection stirring construction method. Specifically, the hardening material is injected at high pressure from the tip 32T of the rotary rod 32 of the high-pressure injection device 30 driven into the ground 10, and the rotary rod 32 is pulled up while being rotated. As a result, the solidification material is injected into the ground 10 near the tip 32T of the rotating rod 32, and the columnar improvement body 28B is formed in order from the lower end.

Here, when the tip portion 32T of the rotating rod 32 passes through the water passage W, the high-pressure injection of the solidifying material from the tip portion 32T is temporarily stopped. As a result, the solidification material is not injected into the ground 10 in the water-permeable portion W, and the water-permeability of the ground 10 is maintained.

By forming the improved columnar bodies 28B while temporarily stopping the high-pressure injection of the solidifying material in this manner, a plurality of water-conducting portions W are provided in the partition wall portion 26S. In addition, in the high-pressure injection stirring method, compared with the mechanical stirring method, it is easier to switch between injection and stop of the solidifying material, so the workability of the water passage W is improved. In the mechanical agitation method, the water passage W can also be formed while temporarily stopping the injection of the solidifying material.

The number, arrangement, shape, and size of the water passage portions W provided in the partition wall portion 26S can be changed as appropriate. Further, when the rigidity of the partition wall portion 26S is reduced by the water passage W, the thickness of the partition wall portion 26S is increased or the distance between the partition wall portion 26S and the other partition wall portions 26 is narrowed. can be

(Underground soil remediation system)
As shown in FIG. 1, the underground soil remediation system 40 employs a biomethod (biostimulation). In the bio-method, for example, an injection solution containing an active agent (nutrient) such as a hydrogen sustained release agent or yeast extract is injected from the injection well 14 into the contaminated ground 10P to decompose the pollutants in the contaminated ground 10P. This is a method of proliferating and activating microorganisms (hereinafter referred to as "degrading microorganisms") to promote purification of contaminants by the degrading microorganisms. Furthermore, in this embodiment, by injecting the heated injection liquid from the injection well 14 into the contaminated ground 10P, the growth and activation of the decomposing microorganisms are promoted.

The subterranean soil remediation system 40 includes a water treatment device 42 and an injection tank 44 . In this underground soil remediation system 40 , groundwater that has passed through the contaminated ground 10</b>P is pumped up from the pumping well 16 and treated by the water treatment device 42 . The treated groundwater is added with the above-described activator in the injection tank 44, and then injected again from the injection well 14 into the contaminated ground 10P.

As described above, the underground soil purification system 40 according to the present embodiment purifies the contaminated ground 10P while circulating groundwater between the contaminated ground 10P and the water treatment device 42 . At this time, the underground soil remediation system 40 uses (combines) the grid-like soil improvement body 22 as a water impermeable wall that suppresses the diffusion of groundwater containing contaminants.

Specifically, the groundwater supplied from the water treatment device 42 is stored in the injection tank 44 as the injection liquid. In the injection tank 44, the above-described activator and the like are appropriately added to the injection solution. In other words, the injection tank 44 is used as an injection solution adjusting tank for adjusting the injection solution.

Further, the injection tank 44 is provided with a heater such as a heater (not shown). This heater heats the groundwater stored in the injection tank 44 to a predetermined temperature at which the decomposing microorganisms are likely to proliferate and activate.

The injection tank 44 is connected to the injection well 14 via an injection pipe 18C. The injection pipe 18C is provided with an injection pump (not shown). By operating the injection pump, the injection liquid stored in the injection tank 44 is supplied to the injection well 14 through the injection pipe 18C. The grouting solution supplied to the grouting well 14 is injected into one of the partitioned regions R1 within the grid-shaped soil improvement body 22 .

The injection liquid injected into one partitioned region R1 is supplied to the other partitioned region R2 through the water passage portion W of the partition wall portion 26S between the one partitioned region R1 and the other partitioned region R2. be. At this time, the grid-like ground improvement body 22 that partitions the one partitioned region R1 and the other partitioned region R2 functions as a water impermeable wall that suppresses the diffusion of groundwater containing contaminants.

A pumping well 16 is connected to the water treatment device 42 via a pumping pipe 18A. A water pump (not shown) is provided in the water pump 18A. By operating this pump, the groundwater in the other partitioned area R2 in the lattice-shaped soil improvement body 22 is supplied from the pumping well 16 to the water treatment device 42 through the pumping pipe 18A.

The water treatment device 42 includes, for example, a filtration device for filtering groundwater pumped from the well 16 . Contaminants and the like are removed from the groundwater pumped from the pumping well 16 by the water treatment device 42 . An injection tank 44 is connected to the water treatment device 42 via a connecting pipe 18B. The connection pipe 18B is provided with a supply pump (not shown). By operating the supply pump, the groundwater treated by the water treatment device 42 is supplied to the injection tank 44 .

Next, the operation of the first embodiment will be described.

As shown in FIG. 2 , the grid-like soil improvement body 22 according to this embodiment has a plurality of partition walls 26 . The liquefaction layer 10B of the ground 10 is partitioned into a plurality of partitioned regions R by the plurality of partition walls 26 . This can effectively suppress liquefaction of the liquefaction layer 10B during an earthquake.

Further, the underground soil remediation system 40 according to this embodiment uses the grid-like soil improvement body 22 as a water impermeable wall. Specifically, the contaminated ground 10P extends over one partitioned region R1 and another partitioned region R2 in the grid-like ground improvement body 22. As shown in FIG. The diffusion of groundwater containing contaminants is suppressed by the grid-like ground improvement body 22 that partitions the one partitioned region R1 and the other partitioned region R2.

By using the grid-like soil improvement body 22 as a countermeasure against liquefaction in this way as the impermeable wall of the underground soil remediation system 40, the construction cost of the impermeable wall can be reduced.

Further, by using the grid-like ground improvement body 22 as a water impermeable wall, the contaminated ground 10P can be purified while constructing the structure 12 on the grid-like ground improvement body 22. Therefore, in this embodiment, the construction period of the structure 12 can be shortened compared to the case where the structure 12 is constructed on the ground 10 after the contaminated ground 10P is purified. As a result, it is possible to shorten the period when the structure 12 can be moved in, and the like.

Here, as a comparative example, when there is no water passage portion W in the partition wall portion 26 between the one partition region R1 and the other partition region R2, the one partition region R1 and the other partition region R2 , an injection well 14 and a pumping well 16, respectively. Therefore, the number of injection wells 14 and pumping wells 16 increases.

On the other hand, in this embodiment, the partition wall portion 26 between one partition region R1 in which the injection well 14 is provided and the other partition region R2 is provided with a water passage portion W for passing groundwater. there is As a result, the injection liquid injected from the injection well 14 into one of the divided regions R1 is supplied through the water passage W to the other divided region R2. Therefore, in the present embodiment, injection wells in other partitioned regions R2 can be omitted. Therefore, in this embodiment, the number of injection wells 14 can be reduced.

A pumping well 16 is provided in another partitioned region R2. From this pumping well 16, the groundwater of another partition area R2 containing pollutants is pumped up. At this time, the groundwater of one partitioned region R1 flows through the water passage W into the other partitioned region R2. Therefore, it is possible to pump up the groundwater in one of the partitioned regions R1 from the pumping wells 16 provided in the other partitioned regions R2. Therefore, in this embodiment, the number of pumping wells 16 can also be reduced.

(Modification of first embodiment)
Next, a modified example of the first embodiment will be described.

In the first modification shown in FIG. 4(A), the contaminated ground 10P straddles the three partitioned regions R1 to R3 in the grid-like ground improvement body 22 aligned in a straight line (in the direction of the arrow X) in plan view. there is In this modification, an injection well 14 is provided in one of the three partitioned regions R1 to R3, one partitioned region R1 on the one end side. A pumping well 16 is provided in another partitioned region R3 on the other end side of the three partitioned regions R.

Here, in the three partitioned regions R1 to R3 aligned on a straight line, the two partitioned wall portions 26S between one partitioned region R1 and the other partitioned region R3 each have a water passage portion W. is provided. Accordingly, in this embodiment, the number of injection wells 14 and pumping wells 16 can be reduced compared to the case where the injection wells 14 and pumping wells 16 are provided in each of the three partitioned regions R1 to R3.

Next, in the second modification shown in FIG. 4(B), of the four partitioned regions R1 to R4 arranged in two directions (arrow X direction and arrow Y direction) in plan view, An injection well 14 is provided in one partitioned region R1, and a pumping well 16 is provided in another partitioned region R4 at a corner diagonal to the one partitioned region R1. A water passage portion W is provided in each of the four partition wall portions 26S between the one partition region R1 and the other partition region R4. Accordingly, in this embodiment, the number of injection wells 14 and pumping wells 16 can be reduced compared to the case where the injection wells 14 and pumping wells 16 are provided in each of the four partitioned regions R1 to R4.

Note that, in the second modification shown in FIG. 4B, for example, as indicated by arrows F1 and F2, there are two routes (shortest routes) from one partitioned region R1 to another partitioned region R4. do. When there are a plurality of paths in this manner, the water passage portion W can be provided in the partition wall portion 26S on any of the paths. In other words, in the second modification shown in FIG. 4B, for example, the water passage portion W can be omitted from the two partition wall portions 26S on the path indicated by the arrow F1 or the arrow F2.

Next, in the third modification shown in FIG. 5(A), one of the nine partitioned regions R1 to R9 arranged in a grid (grid pattern) in plan view is located at the corner. An injection well 14 is provided in R1. A pumping well 16 is provided in another partitioned region R9 located at a corner diagonal to the one partitioned region R1. A water passage portion W is provided in each of the 12 partition wall portions 26S between the one partition region R1 and the other partition region R9. As a result, in this embodiment, the number of injection wells 14 and pumping wells 16 can be reduced compared to the case where the injection wells 14 and pumping wells 16 are provided in each of the nine partitioned regions R1 to R9.

Note that in the third modification shown in FIG. 5(A), the route (shortest route) from one partitioned region R1 to the other partitioned region R9 is similar to the second modification shown in FIG. 4(B). There are multiple In this case, as described above, the water passage portion W can be provided in the partition wall portion 26S on any path.

Next, in the fourth modification shown in FIG. 5(B), the soil improvement body 50 is formed in the shape of the letter "H" in plan view. This soil improvement body 50 has an outer peripheral wall portion 52 and a partition wall portion 54 that partitions the inner region of the outer peripheral wall portion 52 into two partition regions R1 and R2. It is also possible to provide a water passage portion W in the partition wall portion 54 . Further, although not shown, it is possible to provide a water passage portion in the partition wall portion of the soil improvement body formed in the shape of the character "" in plan view.

(Second embodiment)
Next, a second embodiment will be described. In addition, in the second embodiment, members having the same configurations as those in the first embodiment are given the same reference numerals as those in the first embodiment, and description thereof is omitted as appropriate.

As shown in FIG. 6(A), the soil improvement structure 60 according to the second embodiment includes a grid-like soil improvement body 22, an injection well 14, and a pumping well 16.

The grid-like ground improvement body 22 is formed in a grid shape in a plan view. This grid-like ground improvement body 22 has an outer peripheral wall portion 24 and a plurality of partition wall portions 26 . A region (liquefaction layer 10B) inside the outer peripheral wall portion 24 is partitioned into a plurality of partition regions R by the partition wall portion 26 .

The plurality of partitioned regions R includes small partitioned regions Rs and large partitioned regions Rb. The large division area Rb is formed according to the range of the contaminated ground 10P and is wider than the small division area Rs. Specifically, as indicated by the chain double-dashed lines, by omitting a part of the partition wall portions 26K of the regularly arranged partition wall portions 26 (the partition wall portions 26A and the partition wall portions 26B), the large partition can be obtained. A region Rb is formed.

As a result, the partitioned regions R (small partitioned regions Rs) on both sides of the omitted partition wall portion 26K are merged (combined) to form one large partitioned region Rb. The contaminated ground 10P is surrounded by the large division area Rb. The size of the large partitioned region Rb is approximately twice the size of the small partitioned region Rs.

An injection well 14 is provided at one corner (corner) of the large partition region Rb. A pumping well 16 is provided at another corner (corner) of the large partition region Rb that is diagonal to the one corner.

Next, the operation of the second embodiment will be described.

According to the ground improvement structure 60 according to the present embodiment, the grid-like ground improvement body 22 divides the liquefaction layer 10B of the ground 10 into the small division area Rs and the large division area Rb wider than the small division area Rs. do. An injection well 14 and a pumping well 16 are provided in the large partition region Rb.

Here, for example, when the widths of the partitioned regions R by the grid-like ground improvement bodies 22 are all the same, the contaminated ground 10P is likely to span a plurality of partitioned regions R. In this case, since it is necessary to provide injection wells 14 and pumping wells 16 in each of the plurality of divided regions R over which the contaminated ground 10P spans, the number of injection wells 14 and pumping wells 16 increases.

On the other hand, in this embodiment, the large division area Rb is formed according to the extent of the contaminated ground 10P. As a result, the contaminated ground 10P can be prevented from extending over a plurality of partitioned regions R (small partitioned regions Rs). Therefore, in the present embodiment, the number of injection wells 14 and pumping wells 16 can be reduced compared to the case where all the divided regions R have the same size.

(Modified example of the second embodiment)
Next, a modified example of the second embodiment will be described.

In the modification shown in FIG. 6(B) , the soil improvement body 62 has an outer peripheral wall portion 64 and a plurality of partition wall portions 66 . The partition wall portion 66 has a plurality of partition wall portions 66A and partition wall portions 66B. The partition wall 66 partitions the liquefaction layer 10B of the ground 10 into a small partition region Rs, a plurality of medium partition regions Rm, and a large partition region Rb.

The medium partitioned region Rm is wider than the small partitioned region Rs. The large partitioned region Rb is wider than the medium partitioned region Rm. The large division area Rb is formed according to the area of the contaminated ground 10P and surrounds the contaminated ground 10P. Thus, the large division area Rb can be formed according to the area and arrangement of the contaminated ground 10P. Also, the size, arrangement, and number of the small partitioned regions Rs and the medium partitioned regions Rm can be changed as appropriate.

In addition, in the modification shown in FIG. 6B, it is possible to surround the contaminated ground 10P not by the large division region Rb but by the medium division region Rm. In this case, the medium partitioned region Rm becomes a large partitioned region wider than the small partitioned region Rs.

Note that the liquefaction prevention performance of the liquefaction layer 10B may deteriorate in the large partition region Rb. Therefore, in the large partition region Rb, for example, the wall thickness of the partition wall portion 66 may be made thicker than that of the small partition region Rs, or the improved strength of the partition wall portion 66 may be made higher than that of the small partition region Rs.

In addition, in the above-described second embodiment, the injection well 14 and the pumping well 16 are provided in the large partitioned region Rb. And it is also possible to install pumping wells.

(Third embodiment)
Next, a third embodiment will be described. In addition, in the third embodiment, the same reference numerals as in the first embodiment are attached to the same members and the like as those in the first embodiment, and the description thereof will be omitted as appropriate.

As shown in FIGS. 7 and 8, the ground improvement structure 70 according to the third embodiment includes a grid-like ground improvement body 22. As shown in FIGS. This grid-shaped ground improvement body 22 partitions the liquefaction layer 10B of the ground 10 into a plurality of partitioned regions R. As shown in FIG.

Here, as shown in FIG. 7, among the plurality of divided regions R, the ground below the divided region R1 located in the center of the grid-like soil improvement body 22 is the contaminated ground 10P. An extension portion 72 is provided in the partition wall portion 26 (the rectangular partition wall portion 26 surrounded by the two-dot chain line in FIG. 8) that partitions the partition region R1. The extension portion 72 is formed by extending the partition wall portion 26 downward. The extension 72 surrounds the contaminated ground 10P.

More specifically, the extension 72 is formed by improving the ground 10 below the partition wall 26 . This extension portion 72 is located below the other partition wall portion 26 and the outer peripheral wall portion 24 . In addition, in this embodiment, the extension part 72 is formed in the non-liquefaction layer 10A. This extended portion 72 is formed in a frame shape in plan view, and surrounds the contaminated ground 10P.

As shown in FIG. 8, an injection well 14 is provided at one corner (corner) of the partitioned region R1. A pumping well 16 is provided at the other corner (corner) of the partitioned region R1 that is diagonal to the one corner. As shown in FIG. 7, the injection well 14 and the pumping well 16 penetrate the partitioned region R1 (liquefaction layer 10B) and reach the contaminated ground 10P (non-liquefaction layer 10A) surrounded by the extension 72. there is A subterranean soil remediation system 40 is also connected to the injection well 14 and the pumping well 16 .

The injection port 14A of the injection well 14 is provided only at a portion (lower end side) of the injection well 14 that reaches the extended portion 72. As shown in FIG. Similarly, the pumping port 16A of the pumping well 16 is provided only at a portion (lower end side) of the pumping well 16 that reaches the extended portion 72 . Thereby, the flow of the groundwater in division area R1 (liquefaction layer 10B) is controlled.

Next, operation of the third embodiment will be described.

According to the ground improvement structure 70 according to this embodiment, the grid-like ground improvement body 22 partitions the liquefaction layer 10B of the ground 10 into a plurality of partitioned regions R. Further, the grid-like ground improvement body 22 is provided with an extension portion 72 . The extension portion 72 is formed by extending downward the partition wall portion 26 that partitions the central partition region R1 of the grid-like soil improvement body 22 . The extended portion 72 surrounds the contaminated ground 10P below the lattice-shaped soil improvement body 22, thereby suppressing the diffusion of groundwater containing pollutants.

An injection well 14 is provided in the contaminated ground 10P surrounded by the extension 72. As shown in FIG. The injection well 14 penetrates the central demarcated region R1 of the grid-like soil improvement body 22 and reaches the contaminated ground 10P surrounded by the extension 72. As shown in FIG. From this injection well 14, for example, an injection liquid containing an activator or the like can be injected into the contaminated ground 10P.

Thus, in this embodiment, by surrounding the contaminated ground 10P below the grid-like soil improvement body 22 with the extended portion 72 of the grid-like ground improvement body 22, the grid-like ground is separated from the grid-like ground improvement body 22. Construction costs can be reduced compared to the case of forming a water impermeable wall below the improved body 22 .

Further, the injection port 14A of the injection well 14 is formed only on the lower end side of the injection well 14 reaching the extended portion 72. As shown in FIG. As a result, the injection liquid containing the activator and the like can be efficiently injected into the contaminated ground 10P. The number and arrangement of the injection ports 14A can be changed as appropriate. For example, the injection ports 14A may also be provided above the injection well 14.

Furthermore, a pumping well 16 is provided in the contaminated ground 10P surrounded by the extension 72. As shown in FIG. The pumping well 16 penetrates the central partitioned area R1 of the grid-like soil improvement body 22 and reaches the contaminated ground 10P surrounded by the extension 72. Groundwater in the contaminated ground 10</b>P surrounded by the extension 72 can be pumped up from the pumping well 16 .

Moreover, the pumping port 16A of the pumping well 16 is formed only on the lower end side of the pumping well 16 reaching the extension portion 72 . As a result, groundwater in the contaminated ground 10P can be efficiently pumped to the ground. The number and arrangement of the water pumping openings 16A can be changed as appropriate.

(Modified example of the third embodiment)
Next, a modified example of the third embodiment will be described.

In the modified example shown in FIGS. 9 and 10, the contaminated ground 10P is positioned below the grid-like soil improvement body 22. In the modification shown in FIGS. As shown in FIG. 10, the contaminated ground 10P extends over three partitioned regions R1 to R3 aligned in a straight line (in the direction of the arrow X) in plan view.

Here, when the three divided regions R1 to R3 are merged, the outer peripheral wall portion 24 and the dividing wall portion 26 located on the outer periphery of the merged three divided regions R1 to R3 (areas surrounded by two-dot chain lines) is provided with an extension 74, as shown in FIG. The extension portion 74 is formed by extending the outer peripheral wall portion 24 and the partition wall portion 26 downward. The extension 74 surrounds the contaminated ground 10P.

An injection well 14 and a pumping well 16 are provided in the contaminated ground 10P surrounded by the extension 74. As shown in FIG. The injection well 14 is provided in the partitioned region R1 on the one end side among the three partitioned regions R1 to R3. On the other hand, the pumping well 16 is provided in the partitioned region R3 on the other end side among the three partitioned regions R1 to R3. These injection wells 14 and pumping wells 16 pass through the partitioned area R1 or the partitioned area R3 and reach the contaminated ground 10P surrounded by the extension 74. As shown in FIG.

Thus, the extension part 74 can be provided in the grid-like ground improvement body 22 according to the width of the contaminated ground 10P.

(Other modifications)
Next, another modified example will be described. Various modifications will be described below using the first embodiment as an example, but these modifications can also be applied to the second and third embodiments as appropriate.

In the above first embodiment, biostimulation is used as the biomethod, but it is not limited to this. For example, bio-augmentation may be used in which microorganisms cultured outside are injected into the contaminated ground 10P together with an activator or the like. In addition, in the above-described first embodiment, the injection liquid injected from the injection well 14 into the contaminated ground 10P is heated, but the injection liquid does not have to be heated.

Also, the arrangement and number of the injection wells 14 and the pumping wells 16 can be changed as appropriate. Moreover, the pumping well 16 may be provided as required, and can be omitted as appropriate.

Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and one embodiment and various modifications may be used in combination as appropriate. It goes without saying that various aspects can be implemented without departing from the scope.

10 Ground 14 Injection well 16 Pumping well 20 Ground improvement structure 22 Grid-like ground improvement body (ground improvement body)
26 Partition wall 26K Division wall 26S Division wall 50 Ground improvement body 54 Division wall 60 Ground improvement structure 62 Ground improvement body 66 Division wall 70 Ground improvement structure 72 Extension 74 Extension R Division area R1 Division area (one area)
R2 compartmentalized area (other compartmentalized area)
R4 compartmentalized area (other compartmentalized area)
R9 compartmentalized area (other compartmentalized area)
Rs Small division area Rb Large division area W Water passing part

Claims (1)

a ground improvement body that partitions the ground into a plurality of partitioned areas;
An extension part formed by extending a part of the soil improvement body downward and surrounding the contaminated ground below the soil improvement body;
an injection well provided in the contaminated ground surrounded by the extension, for injecting an infusion solution added with an activator that proliferates and activates microorganisms that decompose pollutants in the contaminated ground into the contaminated ground; ,
with
The ground improvement body is
A frame-shaped outer peripheral wall portion in a plan view,
a plurality of partition wall portions connected in a grid pattern in a plan view and partitioning an inner region of the outer peripheral wall portion into a plurality of the partition regions;
has
The extension portion is formed by extending downward the partition wall portion, which is rectangular in plan view and partitions one of the partition regions,
Ground improvement structure.

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