Storage structure and method for constructing the storage structure

Abstract

The present invention provides a storage structure that reduces the scattering of heavy metal-containing soil from the embankment, prevents leachate from flowing out from the sides of the embankment, and has a retaining wall that can be reused after demolition. [Solution] The storage structure 1A comprises a support 4, a retaining wall 5 surrounding a predetermined area on the support 4, and heavy metal-containing soil 3 contained in the area surrounded by the retaining wall 5. The retaining wall 5 has a first wall surface 5a erected on the support 4 and in contact with the heavy metal-containing soil 3, a second wall surface 5b erected on the support 4, spaced apart from the first wall surface 5a and surrounding the first wall surface 5a, and a filler material 5c filled in the space between them. The portion of the first wall surface 5a that contacts the heavy metal-containing soil 3 is made of metal or resin. The density of the filler material 5c is greater than the density of the heavy metal-containing soil 3.

Description

Technical Field

[0001] The present invention relates to a storage structure and a method for constructing the storage structure.

Background Art

[0002] In tunnel construction or the like, rocks and earth and sand containing heavy metals and the like are generated by excavation. These generated soils are temporarily placed until the disposal site or the reuse site is determined. While the generated soil is being temporarily placed, rainwater or the like may come into contact with the generated soil and heavy metals or the like may elute, so it is an issue not to diffuse heavy metals or the like into the surrounding environment.

[0003] To solve this problem, for example, it is conceivable to use the adsorption mat disclosed in Patent Document 1. This adsorption mat is a water-permeable bag filled with an adsorbent. If the generated soil is piled up and temporarily placed on this adsorption mat, heavy metals and the like contained in the leachate can be captured by the adsorbent, so it is expected that heavy metals and the like will not flow out downward.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the embankment is usually not covered, there is also a risk that the generated soil will scatter or the leachate will flow out from the side. To prevent these, it is conceivable to use a concrete L-shaped retaining wall on the side of the embankment. However, when the temporary placement structure is disassembled after the temporary placement is completed, the L-shaped retaining wall is penetrated by the leachate containing heavy metals and the like and cannot be easily washed, so it has to be discarded.

[0006] Therefore, the present invention aims to provide a storage structure having a retaining wall that reduces the scattering of heavy metal-containing soil used for embankment, prevents leachate from flowing out from the sides of the embankment, and allows for reuse after demolition. The present invention also aims to provide a method for constructing such a storage structure. [Means for solving the problem]

[0007] The present invention relates to a storage structure comprising a support laid substantially horizontally, a retaining wall disposed on the support and surrounding a predetermined area on the support, and heavy metal-containing soil contained in the area surrounded by the retaining wall, wherein the retaining wall has a first wall surface erected on the support and in contact with the heavy metal-containing soil, a second wall surface erected on the support and spaced apart from the first wall surface and surrounding the first wall surface, and a filling material filled in the space between the first wall surface and the second wall surface, wherein both the first wall surface and the second wall surface have a base portion having a portion extending along the direction in which the first wall surface and the second wall surface are aligned with the filling material in between, and a rising portion rising upward from the base portion, wherein the portion of the first wall surface in contact with the heavy metal-containing soil is made of metal or resin, and the density of the filling material is greater than the density of the heavy metal-containing soil, etc.

[0008] This storage structure, with its embankment of heavy metal-containing soil surrounded by a retaining wall, reduces the scattering of heavy metal-containing soil and prevents leachate from flowing out from the sides of the embankment. Furthermore, since the density of the filling material within the retaining wall is greater than that of the heavy metal-containing soil, it can adequately support the sliding force of the stored heavy metal-containing soil. In addition, since the part of the retaining wall in contact with the heavy metal-containing soil is made of metal or resin, heavy metals do not penetrate from the soil and the wall is washable. Therefore, the retaining wall can be reused after the storage structure is dismantled.

[0009] In the storage structure of the present invention, the support may be an adsorption layer that adsorbs heavy metals, etc. A structure using an adsorption layer is easier to install and remove compared to shielding heavy metals, etc. with other structures such as waterproofing walls.

[0010] In the storage structure of the present invention, the filling material may be solidified soil obtained by solidifying soil containing heavy metals, etc., with a cement-based solidifying agent. In this case, it is easy to make the density of the filling material greater than the density of the soil containing heavy metals, etc.

[0011] In the storage structure of the present invention, both the first and second wall sections may have a structure comprising a plurality of support columns arranged in the surrounding direction of the retaining wall, and wall materials provided to connect adjacent support columns in each of the first and second wall sections. With such a structure, it is easy to extend the retaining wall upwards, so the storage volume of soil containing heavy metals can be easily increased.

[0012] At least one of the first wall section and the second wall section may have an anchor that protrudes toward the filler material. This prevents the first or second wall section having the anchor from collapsing, as the anchor will be embedded in the filler material.

[0013] The present invention provides a construction method for constructing the above-mentioned storage structure, comprising erecting a first wall section and a second wall section on a support laid in a substantially horizontal direction, filling the space between the first wall section and the second wall section with a filler material, and storing heavy metal-containing soil in an area surrounded by a retaining wall.

[0014] In this construction method, after the heavy metal-containing soil is stored, multiple support columns are provided in both the first and second wall sections, aligned in the direction surrounding the retaining wall. Wall materials are then provided between adjacent support columns in each of the first and second wall sections, and the space increased in height by the provision of wall materials may be further filled with filler material. This allows for handling cases where the amount of heavy metal-containing soil to be stored increases. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a storage structure having a retaining wall that reduces the scattering of heavy metal-containing soil used for embankment, prevents leachate from flowing out from the sides of the embankment, and allows for reuse after demolition. Furthermore, a method for constructing such a storage structure can be provided. [Brief explanation of the drawing]

[0016] [Figure 1] This is a plan view of a storage structure according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] (A) is a plan view of the wall section, and (B) is a front view of the wall section. [Figure 4] This is a magnified view of a portion of Figure 2, illustrating the static frictional force of the retaining wall and the sliding force of the soil containing heavy metals, etc. [Figure 5] This is a cross-sectional view of a storage structure according to another embodiment. [Modes for carrying out the invention]

[0017] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted. In the present invention, "heavy metals, etc." refers to cadmium, hexavalent chromium, cyanide, mercury, selenium, lead, arsenic, fluorine, boron, and compounds thereof, which are classified as Class II specified hazardous substances under the Soil Contamination Countermeasures Act. Therefore, "heavy metals, etc." is a concept that also includes cyanide, arsenic, fluorine, and boron. "Soil containing heavy metals, etc." refers to rocks and soil containing "heavy metals, etc."

[0018] <Storage structure> As shown in FIGS. 1 and 2, the storage structure 1A of the present embodiment has a structure in which the soil 3 containing heavy metals or the like is accommodated in the storage facility 2A. The storage facility 2A is composed of a support 4 laid at a place for temporarily placing the soil 3 containing heavy metals or the like, and a retaining wall 5 disposed on the support 4 and surrounding a predetermined area on the support 4. The soil 3 containing heavy metals or the like is embanked in the area surrounded by the retaining wall 5 to constitute the storage structure 1A. The retaining wall 5 has an annular shape that is quadrangular in plan view. The shape of the ring is arbitrary, and it may be, for example, a circle or an ellipse, or an irregular shape adapted to the shape of the site.

[0019] The support 4 is an adsorption layer 4A that adsorbs heavy metals or the like. Specifically, the adsorption layer 4A is an adsorption mat in which an adsorbent is filled in a flexible and water-permeable bag. The adsorption layer 4A is preferably laid substantially horizontally.

[0020] The retaining wall 5 is composed of a first wall surface portion 5a that contacts the soil 3 containing heavy metals or the like, a second wall surface portion 5b that is separated from the first wall surface portion 5a and surrounds the first wall surface portion 5a, and a filler 5c filled in the space between the first wall surface portion 5a and the second wall surface portion 5b. Both the first wall surface portion 5a and the second wall surface portion 5b are erected on the adsorption layer 4A.

[0021] The first wall surface portion 5a has a first base portion 5aa having a portion extending along the direction in which the first wall surface portion 5a and the second wall surface portion 5b are arranged with the filler 5c sandwiched therebetween, and a first rising portion 5ab rising upward from the first base portion 5aa. Similarly, the second wall surface portion 5b has a second base portion 5ba having a portion extending along the direction in which the first wall surface portion 5a and the second wall surface portion 5b are arranged with the filler 5c sandwiched therebetween, and a second rising portion 5bb rising upward from the second base portion 5ba. At least the portion of the first wall surface portion 5a that contacts the soil 3 containing heavy metals or the like is made of metal or resin.

[0022] The first base portion 5aa and the second base portion 5ba are members that allow the first wall portion 5a and the second wall portion 5b to withstand horizontal loads, and they protrude in a direction perpendicular to the surrounding direction (circumferential direction of the ring) of the retaining wall 5. The shape of the protruding portion may be rod-shaped or plate-shaped.

[0023] The first rising portion 5ab and the second rising portion 5bb are members that form a space to secure the volume of the filler material 5c. In this embodiment, the first rising portion 5ab is inclined toward the second wall portion 5b, and the second rising portion 5bb is vertically rising, both extending upward. Furthermore, the first rising portion 5ab rises from the end of the first base portion 5aa that is furthest from the second wall portion 5b. Similarly, the second rising portion 5bb rises from the end of the second base portion 5ba that is furthest from the first wall portion 5a.

[0024] Both the first rising portion 5ab and the second rising portion 5bb have anchors 5d protruding toward the filler material 5c on the surface that contacts the filler material 5c. Multiple anchors 5d are arranged in both the vertical and horizontal directions.

[0025] As shown in Figures 3(A) and (B), the first rising section 5ab has multiple support columns 6, 6 arranged in the direction surrounding the retaining wall 5, and wall panels 7 provided to connect adjacent support columns 6, 6. In this embodiment, the support columns 6 are H-shaped steel, and the wall panels 7 are horizontal plates whose ends are inserted into grooves in the H-shaped steel. The support columns 6 are erected by inserting their ends into grooves in the U-shaped cross-section foundation beams 8 fixed on the first base section 5aa. The height of the first rising section 5ab is increased by inserting multiple wall panels 7 between the same support columns 6, 6. Although Figure 3 uses the first rising section 5ab as an example for the support columns 6 and wall panels 7, the second rising section 5bb has a similar structure.

[0026] The filling material 5c is filled into the storage facility 2A in proportion to the amount of heavy metal-containing soil 3 to be stored. The filling material 5c uses a material whose density is greater than that of the heavy metal-containing soil 3. Considering the normal density after generation in tunnel construction and other projects, the density of the filling material 5c is 1.8 ton / m³. 3 Preferably, it is 2.0 tons / m 3 It is more preferable that it be 2.2 tons / m 3 It is even more preferable that the filling material 5c is solidified soil obtained by solidifying the heavy metal-containing soil 3 itself with a cement-based solidifying agent. The filling material 5c may also contain an immobilizing agent such as an iron compound. In the storage structure 1A, the filling material 5c is embedded in the anchor 5d.

[0027] The relationship between the amount of filler material 5c in the retaining wall 5 and the amount of heavy metal-containing soil 3 to be filled (contained) is determined by considering the static friction force of the retaining wall 5. Generally, in order for the retaining wall to hold the heavy metal-containing soil, the static friction force F of the retaining wall must be higher than the horizontal sliding force F' of the heavy metal-containing soil (F>F'; see Figure 4). Static friction force F = μN of a retaining wall μ: Coefficient of friction between the retaining wall and the base. N: Normal reaction force Here, for example, if μ is 0.7 and N is the self-weight ρSg of the retaining wall, Static friction force of a retaining wall F = μN = 0.7ρSg ρ: Density of the retaining wall (≈ Density of the filling material) S: Retaining wall area per unit depth (≒ area of ​​filling material) g:Gravity acceleration On the other hand, assuming the angle of the sliding surface of soil containing heavy metals is 45°, Soil containing heavy metals Horizontal sliding force F'=ρ'S'g·cos45°·cos45°=0.5ρ'S'g ρ': Density of soil containing heavy metals, etc. S': Area per unit depth above the sliding surface (shaded area in Figure 4) Therefore, the required "F>F'" is expressed as "0.7ρS>0.5ρ'S'". According to this, by compacting the filler to a density 10% or more greater than that of the heavy metal-containing soil, 0.7 × 1.1ρ'S > 0.5ρ'S' ⇔S>0.65×S' Therefore, the cross-sectional area S of the retaining wall should be at least 65% of the area of ​​the upper part of the sliding surface of the heavy metal-containing soil (the shaded area in Figure 4). Conversely, the area S' of the retaining wall can be filled with heavy metal-containing soil, up to a limit of approximately 1.5 times the cross-sectional area S of the retaining wall.

[0028] <Method for constructing a storage structure> Next, the method for constructing the storage structure 1A will be explained. First, an adsorption layer 4A is laid on the ground. Next, the area where the retaining wall 5 is to be installed is envisioned as a ring shape on the adsorption layer 4A, and the first base section 5aa is installed in a ring shape at the innermost part of this ring. The first base section 5aa may be made of metal or concrete. Then, foundation beams 8 are installed in a ring shape on the first base section 5aa to match the ring shape of the first base section 5aa. The foundation beams 8 are long members with a U-shaped cross-section into which the support columns 6 can be inserted, and they have grooves. The foundation beams 8 are fixed on the first base section 5aa with these grooves facing upwards.

[0029] Multiple support columns 6 made of H-shaped steel are inserted and fixed into grooves in the foundation beam 8 at predetermined equal intervals. The ends of the multiple support columns 6 are inserted into the grooves and erected so that they stand in a line in the direction surrounding the retaining wall 5. It is preferable to fix the support columns 6 to the foundation beam 8 with bolts. After that, wall panels 7 are inserted from above between the support columns 6. In Figure 3, the wall panels 7 are shown inserted in three layers between each support column 6, but the total height of the wall panels 7 is adjusted to match the volume to be filled with the filler material 5c. Although not shown, bracing members spanning between the support columns 6 may be attached to stabilize the erection of the support columns 6.

[0030] Anchors 5d are attached to the support columns 6 at any height. The method of attaching the anchors 5d is not particularly limited, but a method that allows for easy removal and reuse is preferred. Following these steps, the first wall section 5a is completed. Following the same procedure, the second wall section is installed on the outermost part of the area where the retaining wall 5 is to be installed. In the method described above, the first base section 5aa and foundation beam 8 are first formed into a ring shape before the support columns 6 are erected, but it is also acceptable to complete the entire ring shape sequentially while partially completing the first wall section 5a.

[0031] Once the first wall section 5a and the second wall section 5b are completed, the space between the first wall section 5a and the second wall section 5b is filled with a filler material 5c. Here, the filler material 5c is, for example, a mixture of heavy metal-containing soil 3 and a cement-based solidifying agent. The filler material 5c is spread evenly within the space. Then, the filler material 5c is compacted to the extent that its density is higher than that of the heavy metal-containing soil 3. Once the filler material 5c has been compacted, the retaining wall 5 is completed. At the same time, the storage facility 2A, with the retaining wall 5 installed on the adsorption layer 4A, is completed.

[0032] Subsequently, heavy metal-containing soil 3 is used to fill the space enclosed by the retaining wall 5. This completes the storage structure 1A. The amount of heavy metal-containing soil 3 used for filling should satisfy the relationship between the cross-sectional areas S and S' described above. Furthermore, it is preferable that the top surface of the heavy metal-containing soil 3 does not exceed the height of the filler material 5c.

[0033] After the initial filling of heavy metal-containing soil 3 is complete, additional heavy metal-containing soil 3 may be generated, necessitating additional filling. In this case, the support columns 6, wall materials 7, and anchors 5d are extended upwards in both the first wall section 5a and the second wall section 5b, increasing the height of both sections. As these heights increase, the space for filling with the filler material 5c also widens, allowing for further filling of the filler material 5c. In this way, the height of the retaining wall 5 increases, as does the volume of heavy metal-containing soil 3 that can be filled.

[0034] When the temporary storage of the heavy metal-containing soil 3 is complete, the storage structure 1A will be dismantled. The dismantling procedure will be carried out by reversing the construction procedure described above.

[0035] <Effects> The following effects are achieved according to the storage structure 1A and its construction method in this embodiment.

[0036] In the final stage of constructing the storage structure 1A, heavy metal-containing soil 3 can be temporarily placed on top of the storage facility 2A. Since the storage structure 1A is built on top of an adsorption layer 4A that adsorbs the heavy metal-containing soil 3, heavy metals leached from the heavy metal-containing soil 3 by rainwater, etc., can be captured by the adsorbent. Therefore, heavy metals are not allowed to flow downwards. In addition, since the heavy metal-containing soil 3 that has been built up in the storage structure 1A is surrounded by a retaining wall 5, the scattering of the heavy metal-containing soil 3 is reduced, and leachate does not flow out from the sides of the embankment. Furthermore, since the density of the filling material 5c inside the retaining wall 5 is greater than the density of the heavy metal-containing soil 3, it can adequately support the sliding force of the stored heavy metal-containing soil 3. In addition, since the part of the retaining wall 5 that is in contact with the heavy metal-containing soil 3 is made of metal or resin, heavy metals do not penetrate from the heavy metal-containing soil 3, and the retaining wall is washable. Therefore, after dismantling the storage structure 1A, the members constituting the first wall section 5a and the second wall section 5b can be reused.

[0037] To prevent the scattering of heavy metal-containing soil 3 and the outflow of leachate, it is conceivable to use a concrete L-shaped retaining wall. However, when the storage facility is dismantled after the temporary storage of heavy metal-containing soil 3 is complete, leachate containing heavy metals will have permeated the L-shaped retaining wall, making it difficult to clean and thus requiring its disposal. Furthermore, since the L-shaped retaining wall must be manufactured in a factory and then transported, large vehicles are required, limiting the roads and times that can be used. According to the storage structure 1A of this embodiment, the retaining wall 5 can be manufactured on-site using washable materials, thus solving these problems.

[0038] Furthermore, since the support 4 in the storage structure 1A is an adsorption layer 4A, installation and removal are easier compared to shielding heavy metals with other structures such as waterproofing walls.

[0039] Furthermore, in the storage structure 1A, if the filling material 5c is solidified soil obtained by solidifying heavy metal-containing soil 3 with a cement-based solidifying agent, it is easy to make the density of the filling material 5c greater than the density of the heavy metal-containing soil.

[0040] Furthermore, in the storage structure 1A, since both the first wall section 5a and the second wall section 5b have the aforementioned support columns 6 and wall material 7, it is easy to extend the retaining wall 5 upwards, and therefore the storage volume of heavy metal-containing soil 3 can be easily increased.

[0041] Furthermore, in the storage structure 1A, since the first wall section 5a and the second wall section 5b have the aforementioned anchors, the anchors are embedded in the filler material 5c. This prevents the first wall section 5a and the second wall section 5b, which have anchors 5d, from collapsing.

[0042] Furthermore, the storage structure 1A can be made to increase the height of the first wall section 5a and the second wall section 5b by stacking wall materials 7, so that the space increased in height by providing wall materials 7 can be further filled with filling material 5c. This makes it possible to accommodate an increase in the amount of heavy metal-containing soil 3 to be stored.

[0043] Although preferred embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments. For example, in the above embodiments, a storage facility 2A in which the support 4 is an adsorption layer 4A is shown, but a storage facility 2B in which a waterproof sheet 4B is used instead of the adsorption layer 4A may also be used, as shown in Figure 5, storage structure 1B. In this case, a water collection pipe 9 is placed on the waterproof sheet 4B. The water collection pipe 9 is a perforated pipe and collects leachate containing dissolved heavy metals, etc. The collected leachate is pumped up and transferred to a water treatment plant. In addition, even in storage structure 1A, a water collection pipe 9 may be placed on the adsorption layer 4A in case the water permeability of the adsorption layer 4A is insufficient for drainage capacity.

[0044] Furthermore, although the above embodiment shows the retaining wall 5 as an annular shape, it does not necessarily have to be a perfect annular shape. It may be a structure in which part of it is supplemented by other structures other than the retaining wall 5 or by uplifted ground.

[0045] Furthermore, in the above embodiment, the first rising portion 5ab and the second rising portion 5bb constituting the retaining wall 5 are shown to extend upward such that the first rising portion 5ab is inclined toward the second wall portion 5b and the second rising portion 5bb rises vertically. However, the relationship between their inclination and vertical direction may be reversed, and both may rise inclined, or both may rise vertically.

[0046] Furthermore, in the above embodiment, the first rising portion 5ab rises from the end of the first base portion 5aa furthest from the second wall portion 5b, and the second rising portion 5bb rises from the end of the second base portion 5ba furthest from the first wall portion 5a. However, the locations where the first rising portion 5ab and the second rising portion 5bb rise are arbitrary within the portions to which the first base portion 5aa and the second base portion 5ba extend, respectively. For example, the first rising portion 5ab may rise from the center of the first base portion 5aa, and the second rising portion 5bb may rise from the end of the second base portion 5ba closer to the first wall portion 5a.

[0047] Furthermore, although the above embodiment shows a configuration in which the first wall section 5a and the second wall section 5b consist of a support column 6 made of H-shaped steel and a horizontal wall material 7, the first wall section 5a and the second wall section 5b may also be formed using sheet piles. In this case, a certain number of sheet piles are considered as support columns, and the sheet piles between those sheet piles are considered as wall materials.

[0048] Furthermore, although the above embodiment shows an arrangement in which the anchor 5d is attached to the support column 6, the anchor may also be attached to the wall material 7. In addition, the number of anchors 5d attached to the first rising portion 5ab and the second rising portion 5bb may be different, or anchors 5d may be provided to only one of the first rising portion 5ab or the second rising portion 5bb. [Industrial applicability]

[0049] This invention can be used for the temporary storage of soil containing heavy metals, etc. [Explanation of Symbols]

[0050] 1A, 1B... Storage structure, 2A, 2B... Storage equipment, 3... Soil containing heavy metals, etc., 4... Support, 4A... Adsorption layer, 4B... Impermeable sheet, 5... Retaining wall, 5a... Wall surface, 5aa... First base, 5ab... First rising section, 5b... Wall surface, 5ba... Second base, 5bb... Second rising section, 5c... Filling material, 5d... Anchor, 6... Support column, 7... Wall material, 8... Foundation beam, 9... Water collection pipe.

Claims

1. Support structures laid almost horizontally, A retaining wall is placed on the support and surrounds a predetermined area on the support, A storage structure comprising: soil containing heavy metals, etc., contained in an area surrounded by the aforementioned retaining wall, The retaining wall comprises a first wall portion erected on the support and in contact with the heavy metal-containing soil, a second wall portion erected on the support and spaced apart from the first wall portion and surrounding the first wall portion, and a filler material filled in the space between the first wall portion and the second wall portion. The first wall portion and the second wall portion each have a base portion that extends along the direction in which the first wall portion and the second wall portion are aligned with the filler material in between, and a rising portion that rises upward from the base portion. The first wall portion is made of metal or resin in the part that comes into contact with the soil containing heavy metals, etc. A storage structure in which the density of the filling material is greater than the density of the soil containing heavy metals, etc.

2. The storage structure according to claim 1, wherein the support is an adsorption layer that adsorbs heavy metals and the like.

3. The storage structure according to claim 1, wherein the filling material is solidified soil obtained by solidifying the heavy metal-containing soil with a cement-based solidifying agent.

4. The storage structure according to claim 1, wherein both the first wall section and the second wall section each have a plurality of support columns arranged in the direction surrounding the retaining wall, and wall materials provided in each of the first wall section and the second wall section to connect adjacent support columns.

5. The storage structure according to claim 1, wherein at least one of the first wall portion and the second wall portion has an anchor protruding toward the filler material.

6. A method for constructing a storage structure according to claim 1, The first wall section and the second wall section are erected on the support structure laid in a substantially horizontal direction. The space between the first wall portion and the second wall portion is filled with the filler material. A construction method for containing heavy metal-containing soil in an area surrounded by the aforementioned retaining wall.

7. After the heavy metal-containing soil has been placed inside, a plurality of support columns are provided on both the first and second wall sections, arranged in the direction surrounding the retaining wall. In each of the first and second wall sections, a wall material is provided between adjacent support columns. The construction method according to claim 6, wherein the space whose height has been increased by providing the wall material is further filled with the filler material.

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