Rainwater storage block, rainwater storage tank, and construction method for rainwater storage tank

Abstract

A rainwater storage block (11) comprises a plate-shaped body (13), and a plurality of crest parts (18A, 18B, 18C, 18D) projecting from the plate-shaped body (13) toward a first side Z1 in a thickness direction Z of the plate-shaped body (13), wherein: when viewed along the thickness direction Z, the number of crest parts (18A, 18B, 18C, 18D) with respect to the area of the plate-shaped body (13) is 20 / m2 or more; the porosity is 90% or more; and the material used is synthetic resin.

Description

Rainwater storage blocks, rainwater storage tanks, and rainwater storage tank construction methods

[0001] The present invention relates to a rainwater storage block, a rainwater storage tank, and a method for constructing a rainwater storage tank. This application claims priority based on Japanese Patent Application No. 2024-027917 filed in Japan on February 27, 2024, Japanese Patent Application No. 2024-192343 filed in Japan on October 31, 2024, and Japanese Patent Application No. 2024-192350 filed in Japan on October 31, 2024, the contents of which are incorporated herein by reference.

[0002] Conventionally, for example, in order to prevent rivers from overflowing during heavy rainfall, rainwater has been stored in the gaps of rainwater storage tanks buried underground (see, for example, Patent Document 1). The rainwater storage tank is constructed by stacking multiple rainwater storage blocks.

[0003] JP 2011-132740 A

[0004] When building a facility on a rainwater storage tank (rainwater storage block), a high-strength rainwater storage tank is required. High-strength rainwater storage tanks made of concrete are expensive and difficult to construct. To increase the strength of a synthetic resin rainwater storage tank, it is necessary to significantly increase its thickness. However, if the rainwater storage tank becomes heavy, it becomes difficult for a single worker to construct it.

[0005] The present invention has been made in consideration of these problems, and aims to provide a rainwater storage block that maintains rainwater storage performance while reducing mass, a rainwater storage tank equipped with this rainwater storage block, and a construction method for a rainwater storage tank.

[0006] In order to solve the above problems, the present invention proposes the following means: (1) Aspect 1 of the present invention is a method for manufacturing a semiconductor device comprising: a plate-like body; and a plurality of ridges protruding from the plate-like body toward a first side in a thickness direction of the plate-like body, wherein the number of the plurality of ridges relative to the area of ​​the plate-like body when viewed along the thickness direction is 20 / m ２ The rainwater storage block is made of synthetic resin and has a porosity of 90% or more.

[0007] In this invention, for example, a plate-shaped rainwater storage block is placed above the multiple peaks of another rainwater storage block, with the first side facing upward. Rainwater can then be stored in the gaps formed by these multiple rainwater storage blocks. Since the porosity of the rainwater storage block is 90% or more, rainwater storage performance can be maintained. Note that porosity refers to the percentage (%) of the volume of the space within the polygonal prism circumscribing the outer shape of the rainwater storage block other than the rainwater storage block relative to the volume of the polygonal prism. The polygonal prism is determined by the shape of the plate-shaped body. For example, if the plate-shaped body is rectangular, it is a rectangular parallelepiped, and if the plate-shaped body is hexagonal, it is a hexagonal prism. The porosity is preferably 90% or more and 96% or less, and more preferably 92% or more and 96% or less. A porosity equal to or greater than the lower limit can reduce the raw material costs of the rainwater storage block. On the other hand, a porosity equal to or less than the upper limit can ensure the strength of the rainwater storage block. When viewed along the thickness direction, the number of the plurality of ridges relative to the area of ​​the plate-like body is 20 / m ２ As a result, it is possible to prevent the size of each of the plurality of peaks from increasing, and to reduce the mass of the rainwater storage block.

[0008] (2) Aspect 2 of the present invention may be the rainwater retention block according to (1), further comprising a first protrusion provided on the first end surface of at least one of the plurality of peaks and a gate mark provided on the first protrusion. In this invention, for example, when manufacturing the rainwater retention block by injection molding, molten synthetic resin is injected into a mold through a gate located in a portion corresponding to the gate mark. During this process, the synthetic resin accumulates in the portion of the mold corresponding to the first protrusion, thereby preventing the pressure of the synthetic resin near the gate from becoming too high.

[0009] (3) Aspect 3 of the present invention may be the rainwater storage block described in (1) or (2), in which the plate-like body has a polygonal shape when viewed along the thickness direction, and the distance between the center of the peak and the center of the plate-like body is longer than the distance between the center of the peak and the nearest vertex of the plate-like body. The nearest vertex is the vertex of the polygonal plate-like body that is closest to the center of the peak. In this invention, even if the rainwater storage block is formed compactly, it is possible to prevent the peaks from interfering with work, for example, when a worker places their feet on the center of the plate-like body.

[0010] (4) A fourth aspect of the present invention may be the rainwater storage block according to any one of (1) to (3), in which a recess is formed on a side surface of at least one of the plurality of peaks. In this invention, the strength of the peaks with the recess can be increased compared to the strength of the peaks without the recess.

[0011] (5) Aspect 5 of the present invention may be the rainwater storage block according to (4), wherein the end of the recess on the second side in the thickness direction is continuous with the plate-like body. In this invention, the strength of the mountain portion where the recess is formed can be further increased.

[0012] (6) Aspect 6 of the present invention may be the rainwater storage block according to (4) or (5), in which a second convex portion is formed on the bottom surface of the recess. In this invention, the second convex portion can increase the strength of the mountain portion where the recess is formed.

[0013] (7) A seventh aspect of the present invention may be the rainwater storage block according to any one of (1) to (6), further comprising a protrusion protruding from the plate-like body toward the first side. In this invention, the bending strength of the rainwater storage block around an axis intersecting the thickness direction can be increased.

[0014] (8) Aspect 8 of the present invention is a rainwater storage tank having a configuration in which a plurality of rainwater storage blocks according to any one of (1) to (7) are stacked in the thickness direction. In this invention, the rainwater storage tank can be constructed by stacking rainwater storage blocks that maintain rainwater storage performance while reducing mass.

[0015] (9) Aspect 9 of the present invention is a method for constructing a rainwater storage tank, in which a plurality of rainwater storage blocks according to any one of (1) to (7) are stacked in the thickness direction to construct a rainwater storage tank. This invention makes it possible to construct a rainwater storage tank constructed by stacking rainwater storage blocks that have reduced mass while maintaining rainwater storage performance.

[0016] The rainwater storage block, the rainwater storage tank, and the method for constructing the rainwater storage tank of the present invention can reduce the mass while maintaining the rainwater storage performance.

[0017] 11. A cross-sectional view of a rainwater storage tank according to one embodiment of the present invention. A perspective view of a main part of a stack of rainwater storage blocks. A perspective view of a quarter-size rainwater storage block. A plan view of the same rainwater storage block. A view seen from the direction of the arrow A1 in FIG. 3. A perspective view of another rainwater storage block. A perspective view of another other rainwater storage block. A perspective view of a spacer. A perspective view of a rainwater storage block according to a first modified example. A cross-sectional view of the rainwater storage tank according to the first modified example. A cross-sectional view of the rainwater storage tank according to the second modified example. An enlarged perspective view of a part of the inspection hatch in FIG. 11. A cross-sectional view of the rainwater storage tank according to the third modified example. A cross-sectional view of the rainwater storage tank according to the fourth modified example. A cross-sectional view of the rainwater storage tank according to the fifth modified example. A cross-sectional view of the rainwater storage tank according to the sixth modified example. A cross-sectional view of the rainwater storage tank according to the seventh modified example.

[0018] Hereinafter, a first embodiment of a rainwater storage block, a rainwater storage tank, and a method for constructing a rainwater storage tank according to the present invention will be described with reference to FIGS. 1 to 8. FIG.

[0019] 1. Configuration of the Rainwater Storage Tank As shown in Fig. 1, the rainwater storage tank 1 of this embodiment is buried underground G1. The rainwater storage tank 1 is covered with soil. Upstream equipment 60, such as a drainage ditch and a manhole, and downstream equipment 65 are connected to the rainwater storage tank 1. The rainwater storage tank 1, the upstream equipment 60, and the downstream equipment 65 are buried underground G1 around a building 70, such as a house.

[0020] The rainwater storage tank 1 includes a stack of rainwater storage blocks 10 and a storage section 50. The following description will first discuss the stack of rainwater storage blocks 10. As shown in FIG. 2 , the stack of rainwater storage blocks 10 includes multiple rainwater storage blocks 11, 31a, 31b, and 36 according to this embodiment, and a spacer 41 stacked in the thickness direction Z (described later). Note that FIG. 2 does not show a portion of the spacer 41. For example, the stack of rainwater storage blocks 10 includes multiple row units 10a, 10b, 10c, and 10d, each of which is composed of at least one of the rainwater storage blocks 11, 31a, 31b, and 36, or the spacer 41, arranged with the thickness direction Z aligned vertically. The following description will discuss the quarter-size rainwater storage block 11 among the rainwater storage blocks 11, 31a, 31b, and 36.

[0021] 3 to 5, the rainwater storage block 11 is a quarter-size block. The rainwater storage block 11 includes a plate unit 12 and multiple ridge units 17A, 17B, 17C, and 17D. The plate unit 12 includes a plate-shaped body 13, a first ridge (ridge) 14, and a second ridge (ridge) 15.

[0022] As shown in FIG. 4 , the plate-like body 13 is formed in a flat plate shape. In this embodiment, the plate-like body 13 has a square shape when viewed along the thickness direction Z of the plate-like body 13. When viewed along the thickness direction Z, the plate-like body 13 has four corners 13c, 13d, 13e, and 13f. The corners 13c, 13d, 13e, and 13f are arranged in this order counterclockwise when viewed from a first side Z1 (hereinafter simply referred to as the first side Z1) along the thickness direction Z. Note that the plate-like body may have a polygonal shape such as a rectangle, a triangle, or a hexagon when viewed along the thickness direction Z.

[0023] Here, a first direction X and a second direction Y are defined along the main surface 13a of the plate-like body 13 facing the first side Z1. The first direction X and the second direction Y are directions perpendicular to each other.

[0024] The plate-like body 13 has a side extending along the first direction X and a side extending along the second direction Y. A plurality of through holes 13b are formed in the plate-like body 13. In this example, the plurality of through holes 13b have a rectangular shape when viewed along the thickness direction Z. The arrangement of the plurality of through holes 13b will be described later. The shape of the plurality of through holes 13b is not limited to this. Note that, when viewed along the thickness direction Z, the plate-like body 13 has through holes or notches (not shown) formed in portions where mountain units 17A, 17B, 17C, and 17D (described later) are to be arranged. These through holes or notches are formed in shapes corresponding to the mountain units 17A, 17B, 17C, and 17D.

[0025] Each first ridge 14 is formed in a strip shape with the thickness direction of the first ridge 14 aligned with the second direction Y. The multiple first ridges 14 extend in the first direction X and are arranged at intervals from one another in the second direction Y. Each first ridge 14 protrudes from the plate-like body 13 toward the first side Z1. Each second ridge 15 is formed in a strip shape with the thickness direction of the second ridge 15 aligned with the first direction X. The multiple second ridges 15 extend in the second direction Y and are arranged at intervals from one another in the first direction X. Each second ridge 15 protrudes from the plate-like body 13 toward the first side Z1.

[0026] Here, the side opposite to the first side Z1 in the thickness direction Z is defined as a second side Z2 in the thickness direction Z (hereinafter simply referred to as the second side Z2) (see FIG. 3).

[0027] The multiple through holes 13b are formed so as to avoid the multiple first protrusions 14 and the multiple second protrusions 15. When viewed along the thickness direction Z, the multiple through holes 13b are formed in the center of plate pieces (reference numerals omitted) in the plate-like body 13 that are partitioned by the multiple first protrusions 14 and the multiple second protrusions 15. In this example, only one through hole 13b is formed in each plate piece.

[0028] In this embodiment, the configuration of the mountain unit 17A is identical to that of the mountain units 17B, 17C, and 17D. Therefore, the configuration of the mountain unit 17A is indicated by adding the capital letter "A" to the number or number and lowercase alphabetic character of the reference numeral. The configurations of the mountain units 17B, 17C, and 17D corresponding to the mountain unit 17A are indicated by adding the capital letters "B," "C," and "D" to the number or number and lowercase alphabetic character of the reference numeral of the mountain units 17B, 17C, and 17D. This avoids redundant explanation. For example, the mountain portion 18A of the mountain unit 17A, which will be described later, and the mountain portions 18B, 18C, and 18D of the mountain units 17B, 17C, and 17D have the same configuration.

[0029] The mountain unit 17A includes a mountain portion 18A, a first protrusion 19A, a gate mark 20A, and a second protrusion 21A. The mountain portion 18A protrudes from the plate-like body 13 toward the first side Z1. In this example, the mountain portion 18A has a truncated quadrangular pyramid shape with the second side Z2 serving as the bottom surface and the center of the bottom surface opening. That is, when viewed along the thickness direction Z, the mountain portion 18A has a rectangular shape. The length of the mountain portion 18A in the second direction Y is longer than the length of the mountain portion 18A in the first direction X. As shown in FIG. 5, in this example, the draft angle 18dA for the mold of the mountain portion 18A is set to 8°. However, the draft angle 18dA is not particularly limited as long as the rainwater storage block 11 can be molded. The peaks may be in the shape of a polygonal truncated pyramid or a truncated cone (see a rainwater storage block 11A according to a modified example shown in FIG. 9) as long as the center of the bottom surface is open.

[0030] As shown in FIGS. 4 and 5 , a recess 18aA is formed on each side surface of the peak 18A. Each recess 18aA is recessed toward the inside of the peak 18A. Each recess 18aA extends along the side surface in the thickness direction Z. For example, the depth of each recess 18aA recessed from the side surface is constant regardless of its position in the thickness direction Z. The width of each recess 18aA (e.g., the length in the second direction Y of the recess 18aA formed on the side surface facing the first side in the first direction X) gradually narrows toward the second side Z2. The end of each recess 18aA on the first side Z1 is continuous with the end surface 18bA on the first side Z1 of the peak 18A. The end of each recess 18aA on the second side Z2 is continuous with the plate-like body 13.

[0031] As shown in FIG. 4 , the peak 18A is positioned near the corner 13c of the plate-like body 13. When viewed along the thickness direction Z, the distance L1 between the center 18cA of the peak 18A and the center 13g of the plate-like body 13 is longer than the distance L2 between the center 18cA of the peak 18A and the corner (vertex) 13c of the plate-like body 13. The corner 13c is the vertex (corner) of the polygonal plate-like body 13 that is closest to the center 18cA of the peak 18A (i.e., the closest vertex). The center of the peak 18A may be the intersection of the diagonals of the rectangular peak 18A. The recess 18aA may be formed on at least one side of the peak 18A. The distance L1 may be equal to or shorter than the distance L2.

[0032] As shown in FIGS. 4 and 5 , the first convex portion 19A is provided on the end surface 18bA of the ridge portion 18A. In this example, the first convex portion 19A is formed in a cylindrical shape. The gate mark 20A is provided on the first convex portion 19A. In this example, the gate mark 20A is provided on the end surface of the first convex portion 19A on the first side Z1. The gate mark 20A is a mark provided on the rainwater storage block 11 at a position corresponding to the gate of the mold. The gate mark 20A is a gate mark. The gate is an entrance for pouring resin into the space in the mold where the rainwater storage block 11 is molded. During injection molding, the rainwater storage block 11 is molded while connected to, for example, a runner. In this case, when the rainwater storage block 11 is separated from the runner, a convex protrusion may be formed on the rainwater storage block 11 at the separation point. For example, this protrusion becomes a gate mark 20A. The second convex portion 21A is formed on the bottom surface of the recess 18aA facing the first direction X. The second convex portion 21A is spaced in the second direction Y from the surface of the recess 18aA facing the second direction Y. The end of the second convex portion 21A on the first side Z1 is located closer to the second side Z2 than the end surface 18bA of the mountain portion 18A. The end of the second side Z2 of the second convex portion 21A is connected to the plate-like body 13.

[0033] As shown in Figure 4, the peaks 18B, 18C, and 18D are located near the corners 13d, 13e, and 13f of the plate-like body 13, respectively. The end of the peak 18A on the second side Z2 is continuous with the inner peripheral edge of a through-hole or notch formed in the plate-like body 13 corresponding to the peak 18A. The length of the peak 18B in the second direction Y is longer than the length of the peak 18B in the first direction X. The peaks 18C and 18D are similar to the peak 18B.

[0034] The rainwater storage block 11 is made of synthetic resin. Examples of synthetic resins include polyolefin-based resins (e.g., polypropylene resin (PP), polyethylene resin (PE), polyethersulfone resin (PES)), polyester resin, and polyvinyl chloride resin. Polyolefin-based resins having functional groups may also be used as the synthetic resin. Using a modified resin as the synthetic resin improves the rigidity and chemical resistance of the rainwater storage block 11. Furthermore, reinforcing fibers may be mixed into the synthetic resin. Examples of reinforcing fibers include glass fiber and carbon fiber. Mixing reinforcing fibers into the synthetic resin can improve the rigidity of the rainwater storage block 11. Recycled materials may be mixed into the synthetic resin, such as recycled container and packaging materials specified by the Container and Packaging Recycling Act.

[0035] The rainwater storage blocks 31a and 31b are so-called half (1 / 2) size. As shown in FIG. 6 , for example, the rainwater storage block 31a is configured by arranging two rainwater storage blocks 11 in the first direction X and connecting the two rainwater storage blocks 11 to each other with a first connecting member (not shown). The first connecting member is formed of the same material as the rainwater storage blocks 11. In this embodiment, the two members being formed of the same material may mean that the main components of the two members are the same. For example, if recycled materials are mixed into the synthetic resin forming the rainwater storage blocks 11, the components of the synthetic resin forming the rainwater storage blocks 11 vary depending on the recycled materials mixed in. Even in such a case, for example, if the main components of the synthetic resin forming the rainwater storage blocks 11 and the main components of the synthetic resin forming the first connecting member are the same, the first connecting member may be formed of the same material as the rainwater storage blocks 11. The first connecting member does not have to be made of the same material as the rainwater storage blocks 11. For example, the rainwater storage block 31b is formed by arranging two rainwater storage blocks 11 in the second direction Y and connecting the two rainwater storage blocks 11 to each other with a second connecting member (not shown). The second connecting member is made of the same material as the rainwater storage blocks 11.

[0036] 7, the rainwater storage block 36 is a so-called full-size rainwater storage block. For example, the rainwater storage block 36 is configured by arranging two rainwater storage blocks 31a in the second direction Y and connecting the two rainwater storage blocks 31a to each other with a second connecting member.

[0037] For example, if a full-size rainwater storage block 36 manufactured by injection molding is used as is, the rainwater storage block 36 is obtained. On the other hand, after manufacturing the rainwater storage block 36 by injection molding, an operator of the injection molding machine cuts the rainwater storage block 36 at the position of the second connecting member, thereby producing two half-size rainwater storage blocks 31a. After manufacturing the rainwater storage block 36, an operator cuts the rainwater storage block 36 at the position of the first connecting member, thereby producing two half-size rainwater storage blocks 31b. Furthermore, after manufacturing two rainwater storage blocks 31a, an operator cuts each rainwater storage block 31a at the first connecting member, thereby producing four quarter-size rainwater storage blocks 11.

[0038] Assuming that the length of one side of the plate unit 12 of the full-size rainwater storage block 36 is 1, as in this embodiment, the rainwater storage blocks 11, 31a, 31b, 36 may be configured as a 1x1 rainwater storage block 36 (full), a 0.5x1 rainwater storage block 31a, 31b (half), and a 0.5x0.5 rainwater storage block 11 (quarter). The rainwater storage tank 1 may be formed by combining these rainwater storage blocks 11, 31a, 31b, 36. Furthermore, for example, the number of peaks 18A, 18B, 18C, 18D of the half-size rainwater storage blocks 31a, 31b may be half the number of peaks 18A, 18B, 18C, 18D of the full-size rainwater storage block 36. The number of ridges 18A, 18B, 18C, and 18D of the quarter-size rainwater storage block 11 may be one-fourth the number of ridges 18A, 18B, 18C, and 18D of the full-size rainwater storage block 36.

[0039] In the rainwater storage blocks 11, 31a, 31b, and 36, the plate unit 12 and the multiple peak units 17A, 17B, 17C, and 17D may be molded integrally, or the plate unit 12 and the multiple peak units 17A, 17B, 17C, and 17D may be molded as separate components and then integrated by, for example, fitting, joining, or welding. Furthermore, the rainwater storage blocks 11, 31a, 31b, and 36 may be provided with a reinforcing member (cover) (not shown). The reinforcing member may be attached to the plate body 13 and may cover at least a portion of the peak portions 18A, 18B, 18C, and 18D. For example, the reinforcing member may cover a portion of the peak units 17A, 17B, 17C, and 17D or the plate unit 12, where stress is likely to concentrate.

[0040] As shown in FIG. 8 , the spacer 41 is formed in a flat plate shape as a whole. The spacer 41 has a plurality of first protrusions 42 and a plurality of second protrusions 43. Each first protrusion 42 is formed in a strip shape with the thickness direction of the first protrusion 42 aligned with the second direction Y. Each first protrusion 42 extends in the first direction X. The multiple first protrusions 42 are arranged at intervals from one another in the second direction Y. Each second protrusion 43 is formed in a strip shape with the thickness direction of the second protrusion 43 aligned with the first direction X. Each second protrusion 43 extends in the second direction Y. The multiple second protrusions 43 are arranged at intervals from one another in the first direction X.

[0041] The multiple first protrusions 42 and the multiple second protrusions 43 are arranged in a lattice pattern. A through hole 44 is formed between two adjacent first protrusions 42 in the second direction Y and between two adjacent second protrusions 43 in the first direction X. The spacer 41 is made of the same material as the rainwater storage block 11. For example, when viewed along the thickness direction Z, the outer shape of the spacer 41 is the same as the outer shape of the rainwater storage block 11.

[0042] The number of row units constituting the rainwater storage block stack 10 is not limited. As shown in Fig. 2, for example, row unit 10a is the row unit arranged lowest among row units 10a, 10b, 10c, and 10d. Row units 10a, 10b, 10c, and 10d are arranged in this order from bottom to top. For example, row unit 10a has four rainwater storage blocks 36 arranged in a grid pattern, with two in the first direction X and two in the second direction Y. Note that the directions shown in Fig. 2 are based on row unit 10a.

[0043] For example, the tier unit 10b is composed of one rainwater storage block 36, two rainwater storage blocks 31a, two rainwater storage blocks 31b, and four rainwater storage blocks 11. When viewed along the thickness direction Z, in the tier unit 10b, the rainwater storage blocks 11, 31a, 31b, and 36 are all arranged so that the direction of the longer sides of the peaks 18A, 18B, 18C, and 18D is perpendicular to the direction of the longer sides of the peaks 18A, 18B, 18C, and 18D of the four rainwater storage blocks 36 of the tier unit 10a (the first direction X in the tier unit 10a).

[0044] In the tier unit 10b, the rainwater storage block 36 is arranged above the four rainwater storage blocks 36 of the tier unit 10a, straddling the four rainwater storage blocks 36. The rainwater storage blocks 36 of the tier unit 10b are arranged at a 90° angle around an axis along the thickness direction Z relative to the four rainwater storage blocks 36 of the tier unit 10a. The four rainwater storage blocks 11 are arranged at the four corners of the tier unit 10b. Each rainwater storage block 31a is arranged between adjacent rainwater storage blocks 11 in the second direction Y, above two rainwater storage blocks 36 of the tier unit 10a, straddling the two rainwater storage blocks 36. Each rainwater storage block 31b is arranged between adjacent rainwater storage blocks 11 in the first direction X, above two rainwater storage blocks 36 of the tier unit 10a, straddling the two rainwater storage blocks 36. The tier unit 10b may be inverted upside down in the thickness direction Z, as in the modified rainwater storage tank 1A shown in Fig. 10. In this case, it is preferable that the rainwater storage blocks 36 of the tier unit 10b are not rotated 90° around an axis along the thickness direction Z relative to the four rainwater storage blocks 36 of the tier unit 10a.

[0045] The tier unit 10c has the same configuration as the tier unit 10a. The tier unit 10d is composed of a plurality of spacers 41. The plurality of spacers 41 are arranged side by side in the first direction X and the second direction Y. The plurality of spacers 41 are arranged above the four rainwater storage blocks 36 that make up the tier unit 10c.

[0046] The storage unit 50 is not limited as long as it can store the rainwater storage block stack 10. As shown in Fig. 1 , for example, the storage unit 50 has a storage body 51 and a lid 56. The storage body 51 is made of a water-proof sheet. An opening 52 is formed in the top of the storage body 51. The rainwater storage block stack 10 is stored inside the storage body 51. The lid 56 is made of a water-permeable sheet. The lid 56 seals the opening 52 of the storage body 51.

[0047] As shown in FIGS. 11 and 12 , the rainwater storage tank 1B may be provided with an inspection hatch 86. The inspection hatch 86 is, for example, a space formed by not disposing the rainwater storage block stack 10 across the entire height of the rainwater storage tank 1B in the thickness direction Z. The inspection hatch 86 is a space for inspecting the condition of the rainwater storage tank 1B and the water level of the stored rainwater, for example. A manhole 89 is provided above the inspection hatch 86. The manhole 89 penetrates the cover 56 from the ground surface and communicates with the inspection hatch 86. As shown in FIG. 12 , the inspection hatch 86 is formed by multiple rectangular frames 87 arranged at predetermined intervals in the thickness direction Z. The edges of each rectangular frame 87 are supported by the edges of the row units 10a, 10b, 10c, and 10d located at the same height as the rectangular frame 87. Support columns 88 are inserted along each of the four inner corners of the rectangular frame 87. The support columns 88 are connected to the four corners of the rectangular frame 87 with bolts 82. Note that, among the frame members 87a that make up the rectangular frame 87, a reinforcing frame 87d may be fixed between the inner surfaces of the perpendicularly opposing end portions of the frame members 87a that are connected to each other at right angles. This reinforcing frame 87d may also serve as scaffolding. Furthermore, diagonal braces 83 may be provided between adjacent support columns 88.

[0048] The following describes a construction method (hereinafter simply referred to as the construction method) for the rainwater storage tank 1 configured as described above. For example, the construction method constructs the rainwater storage tank 1 having a configuration in which multiple rainwater storage blocks 11, 31a, 31b, 36 are stacked in the thickness direction Z. At this time, the rainwater storage blocks 11, 31a, 31b, 36 may be stacked while changing their orientation around an axis along the thickness direction Z.

[0049] Next, the operation of the rainwater storage tank 1 configured as described above will be described. As shown in Fig. 1, rain that falls on the ground surface G2 flows into the rainwater storage tank 1 as rainwater W, for example, through the upstream equipment 60 or the cover 56 of the rainwater storage tank 1. The rainwater storage tank 1 functions as a tank that temporarily stores the rainwater W, especially during heavy rain. The rainwater W is stored between the row units 10a, 10b, 10c, and 10d of the rainwater storage block stack 10 in the storage section 50. The rainwater W stored in the rainwater storage tank 1 is discharged at a constant flow rate to the downstream equipment 65.

[0050] 2. Consideration of Specifications for Solving the Problems of the Present Application The following describes the results of considering specifications for the rainwater storage block 36 to solve the problem of "reducing mass while maintaining rainwater storage performance," which is the problem of the present application. As shown in Tables 1 and 2, the peak ratio, porosity, peak height, short-term allowable stress, and long-term allowable stress were considered for the rainwater storage blocks 36 of Samples No. 1 to 8.

[0051]

[0052]

[0053] The peak ratio referred to here is the number of peaks 18A, 18B, 18C, and 18D relative to the area of ​​the plate-like body 13 when viewed along the thickness direction Z (number / m ２ The void ratio means the ratio of the space other than the rainwater storage block 36 within the rectangular parallelepiped to the volume of the rectangular parallelepiped circumscribing the outer shape of the rainwater storage block 36. The height of the peaks 18A, 18B, 18C, and 18D referred to here means, for example, the distance between the end face 18bA of the first side Z1 of the peak 18A and the plate-like body 13.

[0054] The term "short-term allowable stress" refers to the allowable stress level (the limit of the resistance force generated by each component) against short-term loads and external forces, such as earthquake force and wind pressure. The short-term allowable stress (allowable stress level) in the table is calculated as "(maximum stress) x (deemed proportional limit coefficient) / (material variation coefficient)." Here, maximum stress refers to the maximum stress observed when "1. Storage Structure Strength Test Method" in the appendix of the "Technical Guidelines for Plastic Underground Storage and Infiltration Facilities (Draft) [Revised Edition, 2018]" (Publisher: Rainwater Storage and Infiltration Technology Association, Public Interest Incorporated Association, Publication Date: April 1, 2018) is performed. The deemed proportional limit coefficient is, for example, 0.7. The material variation coefficient is, for example, 1.3. In actual products, the short-term allowable stress in the table is the upper limit of short-term allowable stress.

[0055] Long-term allowable stress is the stress (1m) that can be tolerated when a load is applied continuously for a long period of time. ２ The long-term allowable stress is determined, for example, by the following method: First, the target long-term allowable stress (1 m ２ The allowable creep load per m is set. Also, the allowable displacement δmax is calculated from the short-term compression test. The allowable displacement δmax is calculated by multiplying the corrected displacement at 70% of the maximum stress by 1 m. ２ This is the difference between the displacement at the allowable creep load (target long-term allowable stress) per unit of stress and the corrected displacement at 70% of the maximum stress. ２ The difference between the displacement at the allowable creep load per unit and the displacement at the allowable creep load per unit is determined by a short-term compression test. The short-term compression test is a test method specified in "1. Storage Structure Strength Test Method" in the aforementioned Appendix. Furthermore, the expected 50-year displacement δ is determined by a creep test. In the creep test, the target long-term allowable stress is applied. The creep test is a test method specified in "2. Storage Structure Long-Term Creep Test Method" in the aforementioned Appendix. If δmax ≥ δ × (material variation coefficient), the target long-term allowable stress can be considered to be the stress that satisfies the conditions. The material variation coefficient is, for example, 1.3. The long-term allowable stress in the table is the upper limit of the stress that satisfies the conditions. In an actual product, the long-term allowable stress in the table is the upper limit of the long-term allowable stress.

[0056] For example, for sample No. 1, the peak ratio is 30 / m ２ The porosity was 93%, the height of the ridges 18A, 18B, 18C, and 18D was 22 cm, and the short-term allowable stress was 200 kN / m ２ and the long-term allowable stress is 70 kN / m ２ is.

[0057] The peak ratio is 20 / m ２ If the ratio is less than 40 / m, the size (height) of the ridges 18A, 18B, 18C, and 18D will be large, and the mass of each rainwater storage block 36 may become heavy. ２ The peak ratio is preferably 40 / m or less. ２ If the thickness exceeds this value, the size of the peaks 18A, 18B, 18C, and 18D will be small, and the thickness of the peaks 18A, 18B, 18C, and 18D will be thin, which may result in insufficient strength.

[0058] When the porosity is less than 92%, ３ On the other hand, if the porosity exceeds 96%, the amount of synthetic resin required to store rainwater will increase, which may result in higher costs. ３ If the amount of synthetic resin required to store the rainwater is too small, the strength of the rainwater storage tank 1 may be insufficient. ３ On the other hand, if the height of the peaks 18A, 18B, 18C, and 18D exceeds 25 cm, the amount of synthetic resin used will be reduced due to the height of the peaks 18A, 18B, 18C, and 18D, which may result in a decrease in strength. Alternatively, if the thickness of the rainwater storage blocks 36 is maintained, the height of the peaks 18A, 18B, 18C, and 18D will increase the weight, which may result in an increase in costs or a decrease in workability.

[0059] Short-term allowable stress is 90 kN / m ２ If the stress is less than 300 kN / m, it may be impossible to install facilities on top of the rainwater storage tank 1 or to perform crane work on top of the rainwater storage tank 1. On the other hand, the short-term allowable stress is 300 kN / m２ If the thickness exceeds 1000 nm, the strength is high, that is, the amount of synthetic resin is large, which may result in high costs.

[0060] Long-term allowable stress is 70 kN / m ２ If the stress is less than 90 kN / m, it may be impossible to install facilities on top of the rainwater storage tank 1 or to perform crane work on top of the rainwater storage tank 1. On the other hand, the long-term allowable stress is 90 kN / m ２ If the thickness exceeds 1000 nm, the strength is high, that is, the amount of synthetic resin is large, which may result in high costs.

[0061] For example, if the peak ratio is 20 / m ２ If the peak ratio is 20 / m or more, the evaluation is "Good (○)". ２ If it is less than this, the evaluation is "× (Bad)". In sample No. 1, the peak ratio was evaluated as "○". Similarly, in sample No. 1, the porosity was evaluated as "○", the height of the peaks 18A, 18B, 18C, and 18D was evaluated as "○", the short-term allowable stress was evaluated as "○", and the long-term allowable stress was evaluated as "○". A sample in which the peak ratio is evaluated as "○" and the porosity is evaluated as "○" is an example with an overall evaluation of "○" or "◎ (Very Good)". A sample in which the peak ratio is evaluated as "×" or the porosity is evaluated as "×" is a comparative example with an overall evaluation of "×".

[0062] Samples No. 1 to No. 3, No. 6, and No. 7 are rainwater storage blocks of the present invention, while Samples No. 4, No. 5, and No. 8 are conventional rainwater storage blocks of comparative examples.

[0063] From the above, in order to solve the problem of "reducing mass while maintaining rainwater storage performance", it is necessary to set the peak ratio of the rainwater storage block 11 to 20 / m. ２ As a result, it was found that a porosity of 90% or more is necessary.

[0064] The mass of the rainwater storage blocks 36 is preferably 6 kg or more and 9 kg or less per unit. If the mass is less than 6 kg per unit, the mass is light, i.e., the amount of synthetic resin is small. Therefore, there is a risk that the strength will be insufficient to install facilities above the rainwater storage tank 1 or to perform crane work above the rainwater storage tank 1. On the other hand, if the mass exceeds 9 kg per unit, the mass will be too heavy and construction may be difficult.

[0065] The planar dimensions of the rainwater storage blocks 36 are preferably 700 mm or more and 1100 mm or less per side. If the planar dimensions of the rainwater storage blocks 36 are less than 700 mm, the number of products required to construct a rainwater storage tank 1 of a given size increases, which may result in a longer construction period. On the other hand, if the planar dimensions of the rainwater storage blocks 36 exceed 1100 mm, the mass per rainwater storage block 36 increases, which may result in poor construction workability. The planar dimensions of the rainwater storage blocks 36 may also be less than 700 mm per side. For example, when actually constructing the rainwater storage blocks 36, it is conceivable that the size (planar dimensions) of the rainwater storage blocks 36 may need to be adjusted to match the shape and size of the rainwater storage tank 1. In this case, when it is preferable that the planar dimensions of the rainwater storage blocks 36 be less than 700 mm per side, the planar dimensions of the rainwater storage blocks 36 may also be less than 700 mm per side. However, even if this is not the case, the planar dimensions of the rainwater storage block 36 may be less than 700 mm per side. Also, the planar dimensions of the rainwater storage block may be shorter than the planar dimensions of the full-size rainwater storage block 36, such as half the length of the planar dimensions of the full-size rainwater storage block 36. In this case, the full-size rainwater storage block 36 can be cut and used as the rainwater storage block.

[0066] The thickness of the rainwater storage block 36 is preferably 1.5 mm or more and 5.0 mm or less. Here, "thickness" refers to the thickness of each component of the rainwater storage block 36. If the thickness is less than 1.5 mm, the rainwater storage tank 1 may not be strong enough due to its thinness. On the other hand, if the thickness exceeds 5.0 mm, the increased thickness may increase the amount of synthetic resin, resulting in higher costs, or the increased mass may make installation difficult. This increases the cycle time of the rainwater storage block 36, making it difficult to manufacture.

[0067] 3. Effects of this embodiment As explained above, in the rainwater storage blocks 36 of this embodiment, for example, the first side Z1 is arranged upward, and the plate-like bodies 13 of one rainwater storage block 36 are arranged above the multiple peaks 18A, 18B, 18C, 18D of another rainwater storage block 36. Then, rainwater W can be stored in the gaps formed by these multiple rainwater storage blocks 36. In this case, since the porosity of the rainwater storage block 36 is 90% or more, the storage performance of the rainwater W can be maintained. In addition, the peak ratio is 20 / m. ２ As a result, the size of each of the plurality of peaks 18A, 18B, 18C, and 18D can be prevented from increasing, and the mass of the rainwater storage block 36 can be reduced.

[0068] The ridge unit 17A has a first protrusion 19A and a gate mark 20A. For example, when manufacturing the rainwater storage block 36 by injection molding, molten synthetic resin is injected into the mold through a gate located at the gate mark 20A. During this process, the synthetic resin accumulates in the mold at the portion corresponding to the first protrusion 19A, preventing excessive pressure buildup in the synthetic resin near the gate. The distance L1 is longer than the distance L2. Therefore, even if the rainwater storage block 36 is formed compactly, the ridges 18A, 18B, 18C, and 18D can be prevented from interfering with the worker's work, for example, when placing their feet on the center of the plate-like body 13.

[0069] A recess 18aA is formed on the side of the peak 18A. This allows the strength of the peak 18A with the recess 18aA formed therein to be increased compared to the strength of the peak 18A without the recess 18aA formed therein. The end of the recess 18aA on the second side Z2 is continuous with the plate-like body 13. This allows the strength of the peak 18A with the recess 18aA formed therein to be further increased.

[0070] The second protrusions 21A are formed on the bottom surfaces of the recesses 18aA facing the first direction X. Therefore, the second protrusions 21A can increase the strength of the mountain portions 18A where the recesses 18aA are formed. The plate unit 12 has the first ridges 14 and the second ridges 15. Therefore, the bending strength of the rainwater storage block 36 (rainwater storage block 11) around an axis that intersects with the thickness direction Z can be increased.

[0071] Furthermore, in the rainwater storage tank 1 of this embodiment, the rainwater storage blocks 11, 31a, 31b, 36 having reduced mass while maintaining rainwater storage performance can be stacked to form the rainwater storage tank 1. Furthermore, in the construction method of this embodiment, the rainwater storage tank 1 can be formed by stacking the rainwater storage blocks 11, 31a, 31b, 36 having reduced mass while maintaining rainwater storage performance.

[0072] Although one embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and configuration changes, combinations, deletions, etc. are also included within the scope of the gist of the present invention. For example, in the above embodiment, the mountain unit 17A may not have at least one of the first protrusion 19A, the gate mark 20A, and the second protrusion 21A. The mountain units 17B, 17C, and 17D are similar to the mountain unit 17A.

[0073] The recess 18aA does not have to be formed on each side of the peak 18A. The end of the recess 18aA on the second side Z2 does not have to be connected to the plate-shaped body 13. The same applies to the peaks 18B, 18C, and 18D. The plate unit 12 does not have to have at least one of the first protrusion 14 and the second protrusion 15.

[0074] In the above embodiment, the rainwater storage tanks 1C to 1G may further include a crushed stone layer 93, as in the rainwater storage tanks 1C to 1G according to the modifications shown in FIGS.

[0075] The crushed stone layer 93 is a layer made of crushed stone and has the function of storing rainwater. Specifically, crushed stone is filled underground and rainwater is temporarily stored in the gaps between the crushed stone. There are two types: a storage type and an infiltration type. Both types reduce the sudden inflow of rainwater into drainage facilities during heavy rain and contribute to preventing flood damage. Furthermore, they are storage tanks that can be installed relatively inexpensively.

[0076] In the rainwater storage tank 1C according to the modified example shown in FIG. 13 , crushed stone layers 93 are arranged on both the left and right side surfaces (opposite side surfaces) of the rainwater storage block stack 10. Each crushed stone layer 93 is formed in a rectangular parallelepiped shape and has a predetermined length in the front-to-back, left-to-right, and up-to-down directions. The lengths of the crushed stone layer 93 in the front-to-back, left-to-right, and up-to-down directions may be determined as appropriate, for example, by referring to the dimensions of the rainwater storage block stack 10. In this embodiment, the lengths of the crushed stone layer 93 in the front-to-back direction (the direction toward the depth of the paper in FIG. 13 ) and up-to-down directions are equal to the lengths of the rainwater storage block stack 10 in the front-to-back and up-to-down directions.

[0077] Each crushed stone layer 93 may be entirely wrapped in a sheet (not shown). This sheet may be either water-permeable or water-resistant, but using a water-permeable sheet is preferable because it is expected that the crushed stone layer 93 will have the rainwater storage function. Also, by wrapping a geotextile around the crushed stone layer 93, the water permeability and strength of the sheet can be improved.

[0078] In this embodiment, both the rainwater storage block stack 10 and the crushed stone layer 93 are rectangular parallelepipeds, but the shapes are not limited to this. For example, a protrusion that protrudes from the crushed stone layer 93 into the rainwater storage block stack 10 may be provided on the side surface of the crushed stone layer 93 that contacts the rainwater storage block stack 10.

[0079] A sheet 99 is provided at the boundary between the crushed stone layer 93 and the rainwater storage block stack 10. The sheet 99 prevents crushed stone from entering the rainwater storage block stack 10 from the crushed stone layer 93. In the illustrated example, the sheet 99 is provided over the entire boundary between the crushed stone layer 93 and the rainwater storage block stack 10. A water-permeable sheet or a water-impermeable sheet can be used as the sheet 99. In addition to sheets made of various materials, geotextiles may also be used for the sheet 99. In order to prevent damage due to frictional forces, etc., the tensile strength of the sheet 99 is preferably 5 kN / m or more.

[0080] In this embodiment, the rainwater storage block stack 10 and the crushed stone layer 93 are wrapped in the sheet 94. Specifically, the sheet 94 is wrapped around the top and bottom surfaces of the rainwater storage block stack 10, the top and bottom surfaces of both crushed stone layers 93, and the side surfaces of the crushed stone layer 93 that are not in contact with the rainwater storage block stack 10.

[0081] A water-permeable sheet or a water-impermeable sheet can be used as the sheet 94. In order to prevent breakage due to frictional forces and the like, the tensile strength of the sheet 94 is preferably 5 kN / m or more.

[0082] The sheets 94, 99 used in this embodiment and the sheet encasing the crushed stone layer 93 must be made of different materials depending on the location where they are used. When using a water-permeable sheet, it is also possible to use a geotextile in addition to the water-permeable sheet. When using a geotextile in combination, the strength of the geotextile can protect other sheets used inside the rainwater storage block stack 10. In particular, geotextiles are useful in the gap between the soil and the crushed stone layer (especially the top surface) because they are stronger than other sheets and allow water and the like to pass through freely.

[0083] The permeable sheet can be made of nonwoven fabric such as polyester long fiber nonwoven fabric. The waterproof sheet can be made of thermoplastic elastomer, ethylene vinyl acetate, vinyl chloride resin, vulcanized rubber, etc. The geotextile can be made of polyethylene, polypropylene, polyester long fiber, or aramid fiber.

[0084] The geotextile may also be wrapped around the top and sides of the rainwater storage block stack 10. In this case, it is effective to protect the surface of the rainwater storage block stack 10 and other sheets, such as the sheet 94, wrapped around the rainwater storage block stack 10.

[0085] One thing to note about sheets is that the materials used need to be different depending on whether the water you want to allow to flow into the rainwater storage block stack 10 is inflow water from a pipeline or seepage water from the ground. In the case of inflow water from a pipeline, it is preferable that the sheet 99 covering the rainwater storage block stack 10 and the crushed stone layer 93 is a water-impermeable sheet to prevent the inflow of water from sources other than the pipeline. On the other hand, in the case of seepage water from the ground, a permeable sheet must be used on the top surface of the rainwater storage block stack 10 to allow water to enter.

[0086] The rainwater storage device 1 of this embodiment has the above-described configuration, and can provide a rainwater storage device that can store a large amount of water and is easy to install. Specifically, the rainwater storage device 1 can store water using the rainwater storage block stack 10 and the crushed stone layer 93, so it can store a large amount of water. Furthermore, since the crushed stone layer 93 is less expensive than the rainwater storage block stack 10, the amount of water stored in the rainwater storage block stack 10 can be reduced by the amount of water stored in the crushed stone layer 93, thereby reducing costs.

[0087] Furthermore, while the rainwater storage block stack 10 generally has the problem of floating due to the floating force caused by the groundwater level, in the rainwater storage device 1 of this embodiment, the rainwater storage block stack 10 is integrated with the crushed stone layer 93, and the weight of the crushed stone layer 93 and the weight of the soil above the crushed stone layer 93 can function as a resistance force against the floating force, preventing floating. In particular, the crushed stone layer 93 has a greater weight per unit volume than the rainwater storage block stack 10, so it is effective as a resistance force against the floating force.

[0088] Normally, the uplift force caused by the groundwater level is countered by increasing the soil cover of the rainwater storage device, thereby increasing the load of the soil above it. However, in this case, a high-strength storage device that can withstand the soil cover is required. As a result, there is a problem of high costs. In this embodiment, the mechanism to prevent such uplift is simply the crushed stone layer 93 and the sheet 94, so there is no need for construction using large-scale heavy machinery, and costs can be reduced.

[0089] Furthermore, in the rainwater storage device 1 of this embodiment, even if force is applied to the upper part of the sheet 94, the sheet 94 will not be pulled out because it passes under the rainwater storage block stack 10 and wraps around the rainwater storage block stack 10 and the crushed stone layer 93. Therefore, there is also the advantage that there is no need to take the trouble of increasing the sheet area in the horizontal direction.

[0090] In a rainwater storage tank 1D according to a modified example shown in Fig. 14, a crushed stone layer 93A is provided on only one side of the rainwater storage block stack 10. A sheet 94A is configured to encase the crushed stone layer 93A and the rainwater storage block stack 10.

[0091] In the rainwater storage tank 1E according to the modification shown in Fig. 15, the crushed stone layer 93B is formed with a predetermined thickness over the entire upper surface of the stacked body of rainwater storage blocks 10, and is also formed on one side of the stacked body of rainwater storage blocks 10 and above it. That is, the crushed stone layer 93B is formed in an L-shape in cross section. The sheet 94B is configured to encase the crushed stone layer 93B and the stacked body of rainwater storage blocks 10.

[0092] In the rainwater storage tank 1F according to the modified example shown in Fig. 16, the height of the crushed stone layer 93C is longer than the height of the rainwater storage block stack 10. Specifically, the crushed stone layer 93C is configured to protrude above and below the rainwater storage block stack 10. Furthermore, the sheet 94C is configured to encase the crushed stone layer 93C and the rainwater storage block stack 10.

[0093] In the rainwater storage tank 1G according to the modified example shown in Fig. 17, the crushed stone layer 93D is formed so as to cover the upper surface and upper side portions of the stacked body of rainwater storage blocks 10. The sheet 94D is configured so as to encase the crushed stone layer 93D and the stacked body of rainwater storage blocks 10.

[0094] The rainwater storage block, rainwater storage tank, and construction method for the rainwater storage tank of the present invention can reduce mass while maintaining rainwater storage performance, and therefore have great industrial applicability.

[0095] 1, 1A, 1B Rainwater storage tank 11 Rainwater storage block 13 Plate-like body 13c, 13d, 13e, 13f Corner 13g Center 14 First ridge (ridge) 15 Second ridge (ridge) 18A, 18B, 18C, 18D Mountain portion 18aA Recess 19A First convex portion 20A Gate mark 21A Second convex portion L1, L2 Distance Z Thickness direction Z1 First side Z2 Second side

Claims

1. A method for manufacturing a semiconductor device comprising: a plate-shaped body; and a plurality of ridges protruding from the plate-shaped body toward a first side in a thickness direction of the plate-shaped body, wherein the number of the plurality of ridges relative to the area of ​​the plate-shaped body when viewed along the thickness direction is 20 / m ２ A rainwater storage block made of synthetic resin, having a porosity of 90% or more.

2. A rainwater storage block as described in claim 1, comprising: a first convex portion provided on the first side end surface of at least one of the plurality of peaks; and a gate mark provided on the first convex portion.

3. A rainwater storage block as described in claim 1, wherein when viewed along the thickness direction, the plate-like body has a polygonal shape, and the distance between the center of the peak and the center of the plate-like body is longer than the distance between the center of the peak and the nearest vertex of the plate-like body.

4. The rainwater storage block according to claim 1, wherein a recess is formed on at least one side surface of the plurality of peaks.

5. A rainwater storage block as described in claim 4, wherein the end of the recess on the second side in the thickness direction is connected to the plate-like body.

6. A rainwater storage block according to claim 4, wherein a second protrusion is formed on the bottom surface of the recess.

7. The rainwater storage block according to claim 1, further comprising a protrusion protruding from said plate-like body toward said first side.

8. A rainwater storage tank having a structure in which a plurality of rainwater storage blocks according to claim 1 are stacked in the thickness direction.

9. A method for constructing a rainwater storage tank, comprising stacking a plurality of rainwater storage blocks according to claim 1 in the thickness direction to construct a rainwater storage tank.

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