Rainwater storage device

Abstract

To provide a rainwater storage device having a large rainwater storage capacity and being easy to construct.SOLUTION: A rainwater storage device according to one aspect of the present invention comprises a first water storage tank 101 having an upper portion that is open and capable of storing rainwater, a foundation layer 102 provided in a lower portion of the first water storage tank, and a second water storage tank 103 provided in a lower portion of the foundation layer 102 and capable of storing rainwater, wherein the second water storage tank 103 comprises a structure 110 in which a plurality of structural members 111 are laminated, and the structural members 111 have a bottom plate and a plurality of protruding strip portions and are made of thermoplastic resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rainwater storage device. [Background technology]

[0002] A flood retarding basin system is known in which a flood retarding basin is placed underground to temporarily store rainwater during rainfall and adjust the amount of rainwater downstream. The flood retarding basin is used as a park or school ground, with the surface of the flood retarding basin serving as an artificial foundation.

[0003] Patent Document 1 describes a flood retarding basin device that uses multiple concrete blocks to store rainwater underground. The flood retarding basin device, which uses concrete to create a large underground space as in Patent Document 1, is installed underground and has a relatively large rainwater storage capacity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-81429 Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, the flood retarding basin device that stores rainwater underground described in Patent Document 1 is not easy to construct because it requires large heavy machinery and a sufficient space around the construction site. Therefore, it is difficult to obtain a flood retarding basin that can store a large amount of rainwater and is easy to construct at the same time.

[0006] An object of the present invention is to provide a rainwater storage device that can store a large amount of rainwater and is easy to install. [Means for solving the problem]

[0007] A rainwater storage device according to one embodiment of the present invention comprises a first water tank having an open top and capable of storing rainwater, a foundation layer provided below the first water tank, and a second water tank provided below the foundation layer and capable of storing rainwater, wherein the second water tank comprises a structure having a structure in which a number of structural members are stacked, the structural members having a bottom plate and a number of protrusions and made of thermoplastic resin. Effect of the Invention

[0008] According to the rainwater storage device of the present invention, it is possible to provide a rainwater storage device that can store a large amount of rainwater and is easy to install. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a rainwater storage device according to a first embodiment of the present invention. [Diagram 2] FIG. 5 is a cross-sectional view showing a rainwater storage device according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a cross-sectional view showing a rainwater storage device according to a third embodiment of the present invention. [Figure 4] FIG. 11 is a cross-sectional view showing a rainwater storage device according to a fourth embodiment of the present invention. [Diagram 5] FIG. 11 is a cross-sectional view showing a rainwater storage device according to a fifth embodiment of the present invention. [Figure 6] FIG. 11 is a cross-sectional view showing a rainwater storage device according to a sixth embodiment of the present invention. [Figure 7] FIG. [Figure 8] 1 is a cross-sectional view showing a structure formed by stacking a plurality of structural members. [Figure 9] FIG. 13 is a perspective view showing a modified example of a structural member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (First embodiment) Hereinafter, a rainwater storage device according to a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the rainwater storage device 100 includes a first water tank 101 , a base layer 102 , a second water tank 103 , a water storage layer 104 , and a wall body 105 . The first water tank 101, the base layer 102, the second water tank 103, and the water storage layer 104 are stacked in this order. In Fig. 1, the direction in which the layers of the first water tank 101, the second water tank 103, etc. are stacked is the Z direction (hereinafter referred to as the up-down direction), the direction perpendicular to the up-down direction and in which the layers extend is the X direction (hereinafter referred to as the left-right direction), and the direction perpendicular to the up-down direction and the left-right direction and in which the layers extend is the Y direction (hereinafter referred to as the front-rear direction).

[0011] The rainwater storage device 100 is provided in a ground layer 119 on which a building or the like is to be installed. Furthermore, as shown in Fig. 1, the rainwater storage device 100 has an open upper side. The rainwater storage device 100 extends in the front-rear, left-right, and up-down directions and has a rectangular parallelepiped shape. The rainwater storage device 100 includes two water tanks (a first water tank 101 and a second water tank 103) capable of storing rainwater.

[0012] The side and bottom surfaces of the rainwater storage device 100 are formed by a wall 105. The wall 105 is installed on a ground layer 119. The wall 105 may be formed of concrete or the like, but is not limited to concrete or the like. The wall 105 includes a side portion 106 and a bottom portion 107. The side portion 106 forms the side surface of the rainwater storage device 100 (the side portion 106 which is parallel to the left-right direction and perpendicular to the front-rear direction is not shown). In other words, the side portion 106 forms the front-rear side surface and the left-right side surface of the rainwater storage device 100. The bottom portion 107 forms the bottom surface of the rainwater storage device 100 and faces a direction perpendicular to the up-down direction. Therefore, the wall body 105 separates the ground layer 119 and the rainwater storage device 100. The lower end of the side portion 106 may be located lower than the lower end of the bottom portion 107 in the vertical direction. Furthermore, the wall body 105 does not have to be installed completely inside the ground layer 119 as shown in FIG. 1, and the upper end of the side portion 106 may protrude above the surface of the ground layer 119.

[0013] The first water tank 101 is a water tank that can store rainwater. Furthermore, the top of the first water tank 101 is open. Therefore, when it rains, the rainwater falls directly into the first water tank 101, and the rainwater is stored. The first water tank 101 is a space formed by the side portion 106 of the wall body 105 and the foundation layer 102. Therefore, the side surface of the first water tank 101 is formed by the portion of the side portion 106 that is above the upper surface of the foundation layer 102. The bottom surface of the first water tank 101 is formed by the foundation layer 102.

[0014] The foundation layer 102 is provided under the first water tank 101. Furthermore, the foundation layer 102 may be configured to be permeable to rainwater. For example, the foundation layer 102 may be configured of a material that allows rainwater to permeate, such as crushed stone or sand. When the foundation layer 102 has water permeability in this way, the porosity of the foundation layer 102 can be increased. Furthermore, crushed stone, sand, etc. are easy to obtain, and are inexpensive and easy to construct compared to when the foundation layer 102 is configured of concrete, etc. Even if soil and sand are deposited in the rainwater storage device 100 due to a large-scale heavy rain, etc., the foundation layer 102 and the second water tank 103 can be easily removed and large-scale cleaning can be performed compared to when the foundation layer 102 is configured of concrete, etc.

[0015] Furthermore, the foundation layer 102 may be configured to be permeable to rainwater over its entire area. In this case, the foundation layer 102 may be configured uniformly over its entire area from a material that is permeable to rainwater, such as crushed stone or sand. On the other hand, the foundation layer 102 may be configured so that rainwater is not permeable uniformly over the entire area. For example, most of the foundation layer 102 may be made of a material such as concrete that is almost impermeable to rainwater, and the remaining part of the foundation layer 102 may be made of a material such as crushed stone or sand that is permeable to rainwater. For example, the foundation layer 102 may be configured so that the central part of the foundation layer 102 is the remaining part, and the foundation layer 102 is inclined toward the central part. In this case, the rainwater stored in the first water tank 101 flows into the central part of the foundation layer 102 and permeates the foundation layer 102. Here, concrete has a larger weight than a material having water permeability such as crushed stone. Therefore, rainwater is stored in the second water tank 103, and the structure 110 can be prevented from floating up due to the buoyancy of water. Furthermore, the foundation layer 102 made of concrete or the like is more robust than the foundation layer 102 made of a material having water permeability such as crushed stone.

[0016] Since the foundation layer 102 is configured to be permeable to rainwater, when the amount of precipitation increases during heavy rain, the rainwater stored in the second water tank 103 may seep up through the foundation layer 102 into the first water tank 101. In this case, the rainwater seeping up from the second water tank 103 is stored in the first water tank 101. Also, when the amount of precipitation decreases to an average or slight amount, the rainwater stored in the first water tank 101 is stored again in the second water tank 103 through the foundation layer 102. At this time, the first water tank 101 is in a state where almost no rainwater is stored. Therefore, even if the amount of precipitation increases due to heavy rain, etc., almost no rainwater is stored in the first water tank 101 after the amount of precipitation decreases, so that the occurrence of pests, birds, and animals can be prevented.

[0017] The second water tank 103 is provided below the foundation layer 102 and is a water tank capable of storing rainwater. The second water tank 103 includes a structure 110 and a sheet (not shown). As shown in FIG. 1, the second water tank 103 is a space formed by a side portion 106 of a wall body 105, the foundation layer 102, and the water storage layer 104. Therefore, the side surface of the second water tank 103 is formed by the side portion 106. The bottom surface of the second water tank 103 is formed by the water storage layer 104. Furthermore, the upper surface of the second water tank 103 is formed by the foundation layer 102.

[0018] The second water tank 103 is provided under the foundation layer 102. Therefore, when the second water tank 103 has a permeable configuration, the rainwater in the first water tank 101 that has permeated from the first water tank 101 to the foundation layer 102 is further permeated and stored in the second water tank 103.

[0019] The water storage layer 104 is a layer capable of temporarily storing rainwater, and is provided below the second water tank 103. Furthermore, the water storage layer 104 is a layer with a high porosity, and may be made of crushed stone or the like.

[0020] The detailed structure of the second water tank 103 will be described below. The upper surface of the second water tank 103 is covered with a sheet. The sheet may be a water-permeable sheet. When the upper surface of the second water tank 103 is covered with the water-permeable sheet and the foundation layer 102 is configured to allow rainwater to permeate, the rainwater that has permeated the foundation layer 102 permeates the upper surface of the second water tank 103 and is stored in the second water tank 103.

[0021] The structure 110 has a structure in which a plurality of structural members 111 are stacked. More specifically, the structure 110 is configured by laying a plurality of structural members 111 in the front-rear and left-right directions and further stacking them in the up-down direction.

[0022] The structural member 111 has a bottom plate 115 and a plurality of protrusions 112. More specifically, as shown in Fig. 7, a plurality of protrusions 112 are arranged side by side on the bottom plate 115 at regular intervals in the front-rear and left-right directions. Note that Fig. 7 shows the structural member 111 in which the bottom plate 115 is formed in a square shape and four protrusions 112 are arranged side by side on the bottom plate 115 in the front-rear and left-right directions, but the structure is not limited to this. As described later, the structural member 111 may have two or more rows of protrusions 112 arranged side by side in each of the front-rear and left-right directions. The structural member 111 is preferably made of a thermoplastic resin.

[0023] 7, the lower ends of the multiple protrusions 112 penetrate the bottom plate 115 and are completely open below the bottom plate 115. Therefore, the inside of the protrusions 112 is hollow. The protruding portion 112 includes a top wall plate 113a, an inclined peripheral wall plate 113b, and a plurality of protruding portions 114, 114. The top wall plate 113a is a rectangular shape that is long in the front-rear direction when the up-down direction in the cross-sectional view of FIG. 8 is taken as the front-rear direction. Furthermore, the top wall plate 113a includes a water passage hole 113c that allows rainwater to pass through inside the protruding portion 112. The number of water passage holes 113c may be two, one, or three or more. The water passage hole 113c may not be present. The inclined peripheral wall plate 113b has a certain height and extends downward from the four edges of the top wall plate 113a on the front, rear, left, and right sides in a fan-shaped manner. The protruding portion 112 is formed so that when viewed from the front side, which will be described later, it has an isosceles trapezoid shape with the upper end portion of the protruding portion 112 cut off.

[0024] The inclined peripheral wall plate 113b includes a front inclined peripheral wall plate portion 113b-1, a rear inclined peripheral wall plate portion 113b-2, a one-side inclined peripheral wall plate portion 113b-3, and an other-side inclined peripheral wall plate portion 113b-4. When referring to both the front-side inclined peripheral wall plate portion 113b-1 and the rear-side inclined peripheral wall plate portion 113b-2, they are referred to as the front-rear inclined peripheral wall plate portions 113b-1 and 113b-2. Similarly, when referring to both the one-side inclined peripheral wall plate portion 113b-3 and the other-side inclined peripheral wall plate portion 113b-4, they are referred to as the two-side inclined peripheral wall plate portions 113b-3 and 113b-4.

[0025] The front and rear inclined peripheral wall plate portions 113b-1, 113b-2 face in the front-rear direction. The front and rear ends of the both side inclined peripheral wall plate portions 113b-3, 113b-4 are connected to both side ends of the front and rear inclined peripheral wall plate portions 113b-1, 113b-2 at right angles over the entire length.

[0026] Two protrusions 114 are provided at both ends of the long side of the top wall panel 113a of the protruding portion 112. Hereinafter, the two protrusions 114 will be collectively referred to as protrusions 114, 114. Furthermore, both protrusions 114, 114 have the same shape. Therefore, each of the protrusions 114, 114 has a constant height and a constant width in the front-rear direction.

[0027] More specifically, the protrusions 114, 114 are provided across the entire width of the top wall plate 113a. Furthermore, the interior of each of the protrusions 114, 114 is connected to the inside of the protruding stripe 112 and is formed hollow. The top surfaces of the protrusions 114, 114 are formed flat. Furthermore, the end surfaces of the protrusions 114, 114 facing outward of the protruding stripe portion 112 are continuous with the upper ends of the inclined peripheral wall plates 113b-3, 113b-4 without any step. Therefore, the end surfaces of the protrusions 114, 114 have the same inclination angle as the inclined peripheral wall plates 113b-3, 113b-4. Furthermore, the distance between the inner surfaces of the protrusions 114, 114 facing each other in the front-rear direction is equal to the width between the lower ends of the inclined peripheral wall plates 113b-3, 113b-4, or is slightly wider than the width. Furthermore, like the top wall plate 113a, the top surfaces of the protrusions 114, 114 may each be provided with a water passage hole.

[0028] The bottom plate 115 has a constant thickness and a rectangular shape in plan view, and includes a central bottom plate portion 115a, a rectangular bottom plate portion 115b, both side bottom plate portions 115c, and a rectangular outer peripheral frame 115d. The central bottom plate portion 115a connects the lower ends of the opposing inclined peripheral wall plate portions 113b-3, 113b-4 of the protruding portions 112, 112 adjacent in the left-right direction. The rectangular bottom plate portion 115b connects the lower ends of the mutually opposing front and rear inclined peripheral wall plate portions 113b-1, 113b-2 in the protruding portions 112, 112 adjacent to each other in the front-rear direction.

[0029] The rectangular outer peripheral frame 115d has a certain height and protrudes upward from the four peripheral edges of the bottom plate 115. In detail, the rectangular outer peripheral frame 115d protrudes so as to surround the lower ends of the bottom plates 115 arranged side by side in the front-rear and left-right directions. The bottom plate portions 115c, 115c protrude horizontally from the lower ends of the inclined peripheral wall plate portions 113b-3, 113b-4 of the protrusion portion 112. Furthermore, the bottom plate portions 115c, 115c are integrally connected to the inner surfaces of the lower ends of the frame portions 115d-1, 115d-2 of the rectangular peripheral frame 115d. The lower end of the rear inclined peripheral wall plate portion 113b-2 located at the front and rear edge portions at the outer peripheral edge of the bottom plate 115 and the lower end of the front inclined peripheral wall plate portion 113b-1 of the other protrusion portion 112 are integrally connected to the inner surfaces of the front and rear frame portions of the rectangular outer peripheral frame 115d.

[0030] The bottom plate 115 further includes a central engagement recess 116 and two side engagement recesses 117, 117. The central engagement recess 116 is provided between the central portions at the lower ends of the two side inclined peripheral wall plate portions 113b-3, 113b-4 that face each other. Furthermore, the two side engagement recesses 117, 117 are provided in the two side bottom plate portions 115c, 115c. Note that the engagement recesses 116, 117 are used to refer to both the central engagement recess 116 and the two side engagement recesses 117, 117.

[0031] The engagement recesses 116, 117 are formed to open downward in the vertical direction and engage with the protrusions 114, 114. More specifically, they are formed to bulge upward in a shape equal to the shape extending from the top surfaces of the protrusions 114, 114 to the two side inclined peripheral wall plate portions 113b-3, 113b-4.

[0032] A method of stacking the structural members 111 when stacking the structural members 111 successively while changing their direction at right angles to form the structure 110 will be described below with reference to Fig. 8. Fig. 8 shows the structure 110 when three structural members 111 are stacked, that is, in three layers. The three structural members 111 are, from the bottom in the vertical direction, a first structural member A, a second structural member B, and a third structural member C. As shown in Fig. 8, the second structural member B is stacked on the first structural member A by changing its direction at a right angle to the first structural member A, and the third structural member C is stacked on the second structural member B by changing its direction at a right angle to the second structural member B.

[0033] The following describes lamination of the second structural member B onto the first structural member A. Note that lamination of the third structural member C onto the second structural member B corresponds to lamination of the second structural member B onto the first structural member A. First, the central portion of the lower ends of the two inclined peripheral wall plate portions 113b-3, 113b-4 of the protrusion portion 112 of the second structural member B is supported by the end portion of the top wall plate 113a of the protrusion portion 112 of the first structural member A. More specifically, the central portion of the lower end is engaged with the lower ends of the inner surfaces of the convex portions 114, 114 protruding upward from both ends of the top wall plate 113a of the first structural member A.

[0034] Furthermore, the central engagement recess 116 of the second structural member B is fitted between the opposing convex portions 114, 114 of the two adjacent protrusions 112 of the first structural member A, covering the convex portions 114, 114. Therefore, the lower surface of the central engagement recess 116 abuts against and is supported by the top surfaces of the convex portions 114, 114.

[0035] Furthermore, the two engaging recesses 117 in the second structural member B cover the opposing convex portions 114, 114 in the two adjacent protruding portions 112 of the first structural member A, and are supported by the convex portions 114, 114.

[0036] As explained above, first, the second structural member B is stacked in a direction changed so as to intersect with the first structural member A at a right angle. Then, the lower center portion of the second structural member B is inserted between the protrusions 114, 114 of the first structural member A, and this lower center portion is engaged by the surfaces of the protrusions 114, 114 of the first structural member A. At the same time, the engaging recesses 116, 117 of the second structural member B are supported by the protrusions 114, 114 of the first structural member A. In this manner, a structure 110 is formed by stacking a plurality of structural members 111.

[0037] According to the above configuration, the rainwater storage device 100 includes the first water tank 101 and the second water tank 103. Therefore, by including these two water tanks in the rainwater storage device 100, a rainwater storage device with a large amount of rainwater storage can be obtained. Furthermore, the second water tank 103 includes a structure 110 having a structure in which a plurality of structural members 111 are stacked. The structural member 111 has a bottom plate 115 and a plurality of protrusions 112, and is made of a thermoplastic resin. Therefore, for example, the second water tank 103 can be formed by stacking the structural members 111, and therefore construction is easier than the conventional technology in which a plurality of concrete blocks are used. Therefore, the amount of heavy machinery required for construction can be minimized, and construction can be performed in a small space. Therefore, a rainwater storage device that can store a large amount of rainwater and is easy to construct can be obtained.

[0038] Furthermore, according to the above configuration, the foundation layer 102 has water permeability. Therefore, rainwater in the first water tank 101 can permeate into the foundation layer 102 and further into the second water tank 103. It is also possible for rainwater in the second water tank 103 to permeate into the foundation layer 102 and further into the first water tank 101. Therefore, for example, during normal rainfall other than heavy rain, rainwater in the first water tank 101 can permeate into the foundation layer 102 and further into the second water tank 103. Therefore, almost no rainwater accumulates in the first water tank 101. In contrast, an example of a conventional rainwater storage device is an open-type reservoir. An open-type reservoir is installed on the ground, and the top of the reservoir is open. In the case of an open-type reservoir, rainwater is often stored in the reservoir at all times, and since the open-type reservoir is an environment in which living things can easily grow, pests and birds and animals are likely to appear in the reservoir. In particular, in the case of an open-type reservoir installed near an airport, etc., birds flying in can cause bird damage and may even lead to airplane accidents. On the other hand, in the rainwater storage device 100, almost no rainwater accumulates in the first water tank 101 during normal rainfall, so that it is possible to prevent the occurrence of pests and bird damage. Furthermore, when rainwater permeates the second water tank 103 during heavy rain and exceeds the capacity of the second water tank 103, the rainwater in the second water tank 103 seeps up and accumulates in the first water tank 101. After the rainwater is drained from the rainwater storage device 100, the first water tank 101 is in a state where almost no rainwater accumulates therein, as in normal rainfall.

[0039] Second embodiment A rainwater storage device 200 according to a second embodiment of the present invention will be described with reference to Fig. 2. The rainwater storage device 200 according to this embodiment has a similar configuration to the rainwater storage device 100 according to the first embodiment. The differences between the rainwater storage device 100 according to the first embodiment and this embodiment will be described below. In this embodiment, the foundation layer 102 may be configured to have no water permeability. Specifically, the foundation layer 102 may be configured of a material having little or almost no water permeability, such as concrete or soil cement. In this case, the rainwater in the first water tank 101 hardly or not at all permeates the foundation layer 102. Therefore, the rainwater in the first water tank 101 is not stored in the second water tank 103 through the foundation layer 102.

[0040] The rainwater storage device 200 according to this embodiment may include a pipe 120 through which rainwater in the first water tank 101 is drained to the lower part of the second water tank 103. Therefore, the pipe 120 may connect the first water tank 101 and the second water tank 103, or may connect the first water tank 101 and the water storage layer 104. When the rainwater in the first water tank 101 is drained through the pipe 120, the rainwater in the first water tank 101 is drained to the second water tank 103 or the water storage layer 104. In this embodiment, the rainwater in the first water tank 101 is stored in the second water tank 103 by drainage from the pipe 120, not by permeation from the base layer 102.

[0041] The sheet covering the upper surface of the second water tank 103 described above may be a waterproof sheet that is impermeable. When the upper surface of the second water tank 103 is covered with the waterproof sheet, even if the base layer 102 is configured to be permeable to rainwater, the rainwater does not permeate the upper surface of the second water tank 103, and the rainwater is not stored in the second water tank 103. In this case, the rainwater storage device 100 may be provided with a pipe 120 that drains the rainwater in the first water tank 101 to the lower part of the second water tank 103. Even when the upper surface of the second water tank 103 is covered with a waterproof sheet, the pipe 120 can store the rainwater in the second water tank 103.

[0042] According to the configuration of the above embodiment, the system further includes a pipe 120 through which the rainwater in the first water tank 101 is drained to the bottom of the second water tank 103. Therefore, the rainwater can be treated not only by storing it in the first water tank 101, but also by draining it to the bottom of the second water tank 103. Therefore, the rainwater treatment capacity can be improved.

[0043] Third embodiment A rainwater storage device 300 according to a third embodiment of the present invention will be described with reference to Fig. 3. The rainwater storage device 300 according to this embodiment has a similar configuration to the rainwater storage device 100 according to the first embodiment. The differences between the rainwater storage device 100 according to the first embodiment and this embodiment will be described below. In this embodiment, the first water tank 101 may be configured to cover at least a part of the upper part of the second water tank 103. Therefore, the area of ​​the lower surface of the first water tank 101 may be equal to or larger than the area of ​​the upper part of the second water tank 103.

[0044] In a plan view, the area of ​​the first water tank 101 is larger than the area of ​​the second water tank 103. In a plan view, the second water tank is located inside the outer periphery of the first water tank. In the rainwater storage device 100 according to the first and second embodiments shown in Fig. 1 and Fig. 2, only the second water tank is located directly below the first water tank. In contrast, in the rainwater storage device 300 according to this embodiment shown in Fig. 3, not only the second water tank but also the ground layer 119 is located directly below the first water tank. 3, in this embodiment, the side 106 of the wall 105 includes a first side 106a and a second side 106b. Similarly, the bottom 107 includes a first bottom 107a and a second bottom 107b.

[0045] The first side portion 106a and the second side portion 106b form the side surface of the rainwater storage device 300. In other words, the first side portion 106a and the second side portion 106b form the side surface in the front-rear direction and the side surface in the left-right direction of the rainwater storage device 300. In detail, the first side portion 106a covers the side surface of the first water storage tank 101 and the foundation layer 102, and the second side portion 106b covers the side surface of the second water storage tank 103 and the water storage layer 104. Therefore, the second side portion 106b forms the side surface of the second water storage tank 103 and the water storage layer 104. Furthermore, a part of the foundation layer 102 forms the upper surface of the second water storage tank 103. Also, when the rainwater storage device 300 is viewed from above, the rainwater storage device 300 is formed in a quadrangle shape.

[0046] The first bottom 107a forms a portion of the base layer 102 that does not form the upper surface of the second water tank 103. Furthermore, the second bottom 107b forms the lower surface of the water storage layer 104. Therefore, the first bottom 107a and the second bottom 107b form the bottom surface of the rainwater storage device 300. The second bottom 107b connects the first side portion 106a and the second side portion 106b.

[0047] The bottom surface of the foundation layer 102 (the bottom surface on the second bottom portion 107b) that does not form the upper surface of the second water tank 103 may be inclined toward the bottom surface of the foundation layer 102 that forms the upper surface of the second water tank 103. In this case, water that permeates from the first water tank 101 into the foundation layer 102 or rainwater that exists on the foundation layer 102 flows toward the bottom surface of the foundation layer 102 that forms the upper surface of the second water tank 103, and moves downward.

[0048] According to the above configuration, the first water tank 101 does not have to cover the entire upper part of the second water tank 103, but only needs to cover at least a part of the upper part of the second water tank 103. This increases the degree of freedom in the position and size at which the second water tank 103 is installed, and increases the degree of freedom in construction.

[0049] (Fourth embodiment) A rainwater storage device 400 according to a fourth embodiment of the present invention will be described with reference to Fig. 4. The rainwater storage device 400 according to this embodiment has a similar configuration to the rainwater storage device 300 according to the third embodiment. The differences between the rainwater storage device 300 according to the third embodiment and this embodiment will be described below.

[0050] The base layer 102 in this embodiment may have a non-permeable structure, similar to the base layer 102 in the second embodiment. Specifically, the base layer 102 may be made of a material having little or almost no permeability, such as concrete or soil cement. Furthermore, the rainwater storage device 400 according to this embodiment may have a pipe 120 through which rainwater in the first water tank 101 is drained to the lower part of the second water tank 103, similar to the rainwater storage device 200 in the second embodiment.

[0051] According to the configuration of the above embodiment, the system further includes a pipe 120 through which the rainwater in the first water tank 101 is drained to the bottom of the second water tank 103. Therefore, the rainwater can be treated not only by storing it in the first water tank 101, but also by draining it to the bottom of the second water tank 103. Therefore, the rainwater treatment capacity can be improved.

[0052] Fifth embodiment A rainwater storage device 500 according to the fifth embodiment of the present invention will be described with reference to FIG. 5. The rainwater storage device 500 according to this embodiment has the same configuration as the rainwater storage device 100 according to the first embodiment. The difference between the rainwater storage device 100 according to the first embodiment and this embodiment will be described below. The third water tank 108 in this embodiment may further include a third water tank 108 that is provided alongside the first water tank 101 and can store rainwater, and a second base layer 109 provided on the upper part of the third water tank. In order to distinguish between the second base layer 109 and the base layer 102, the base layer 102 is conveniently referred to as the first base layer 102. The third water tank is a space formed by the wall body 105 and the first water tank 101 , as well as the second base layer 109 and the second water tank 103 . The second base layer 109 has a similar structure to the first base layer 102, but the second base layer 109 has water permeability. The third water tank 108 includes a structure 110 similar to the second water tank 103.

[0053] In this embodiment, the first water tank 101 covers a part of the upper part of the second water tank 103. However, this embodiment does not include a case where the first water tank 101 completely covers the upper part of the second water tank 103. The third water tank 108 covers at least a part of the remaining part of the upper part of the second water tank 103. Here, the "remaining part of the upper part of the second water tank 103" refers to the part of the upper part of the second water tank 103 that is not covered by the first water tank 101. In this case, since the second foundation layer 109 has water permeability, rainwater that falls on the second foundation layer 109 permeates the second foundation layer 109 and is stored in the second water tank 103. The first water tank 101 covers at least a part of the side of the third water tank 108. Therefore, the third water tank 108 is provided side by side with the first water tank 101. This increases the degree of freedom in the position and size of the second water tank, and increases the degree of freedom in construction.

[0054] In this embodiment, wall 105 includes a third side 106c, a fourth side 106d, and a third bottom 107c.

[0055] The third side portion 106c forms the side surface of the rainwater storage device 500. In other words, the third side portion 106c forms the front-rear and left-right side surfaces of the rainwater storage device 500. In detail, the third side portion 106c covers the outer side surfaces of the first water tank 101, the first foundation layer 102, the second foundation layer 109, the second water tank 103, the third water tank 108, and the water storage layer 104. Also, when the rainwater storage device 500 is viewed from above, the rainwater storage device 500 is formed in a quadrangle shape.

[0056] The fourth side portion 106d covers the front-rear and left-right sides located inside the first water tank 101 and the first foundation layer 102, the second foundation layer 109, and the third water tank 108, and the third side portion 106c covers the front-rear and left-right sides located inside the first water tank 101 and the first foundation layer 102, the second foundation layer 109, and the third water tank 108. Therefore, as shown in FIG. 5, the fourth side portion 106d separates the first water tank 101 and the first foundation layer 102 from the second foundation layer 109 and the third water tank 108.

[0057] The third bottom 107c forms a portion of the first water tank 101 that does not cover the upper surface of the second water tank 103. Furthermore, the third bottom 107c forms the lower surface of the water storage layer 104. Therefore, the third bottom 107c forms the bottom surface of the rainwater storage device 500.

[0058] According to the above configuration, the rainwater storage device 500 may include a third water tank 108 that is provided alongside the first water tank 101 and can store rainwater. This increases the degree of freedom in terms of the location and size of the second water tank 103, and increases the degree of freedom in construction. Furthermore, the third water tank 108 includes a structure 110. This allows rainwater to be directly stored in the structure 110 in the third water tank 108.

[0059] Sixth embodiment A rainwater storage device 600 according to a sixth embodiment of the present invention will be described with reference to Fig. 6. The rainwater storage device 600 according to this embodiment has a similar configuration to the rainwater storage device 500 according to the fifth embodiment. The differences between the rainwater storage device 500 according to the fifth embodiment and this embodiment will be described below.

[0060] The first foundation layer 102 and the second foundation layer 109 in this embodiment may be configured to have no water permeability, similar to the foundation layer 102 in the second or fourth embodiment. Specifically, the first foundation layer 102 and the second foundation layer 109 may be configured of a material having little or almost no water permeability, such as concrete or soil cement. Furthermore, the rainwater storage device 600 according to this embodiment may be provided with a pipe 120 through which rainwater in the first water tank 101 is drained to the lower part of the second water tank 103, similar to the rainwater storage device 200 or 400 in the second or fourth embodiment.

[0061] According to the configuration of the above embodiment, the system further includes a pipe 120 through which the rainwater in the first water tank 101 is drained to the bottom of the second water tank 103. Therefore, the rainwater can be treated not only by storing it in the first water tank 101, but also by draining it to the bottom of the second water tank 103. Therefore, the rainwater treatment capacity can be improved.

[0062] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0063] Furthermore, the piping 120 may be provided not only in the rainwater storage device 200 according to the second embodiment, but also in rainwater storage devices according to other embodiments.

[0064] For example, in an embodiment in which the foundation layer 102 is configured to be permeable to rainwater, in addition to the foundation layer 102, the rainwater in the first water tank 101 is drained to the second water tank 103 or a lower portion of the second water tank 103 via the piping 120. Therefore, compared to a case in which the rainwater storage device 100 is not provided with the piping 120, the amount of rainwater drained from the first water tank 101 can be increased. In this way, the rainwater in the first water tank 101 may be stored in the second water tank 103 only through the piping 120 connecting the first water tank 101 and the second water tank 103, or it may be stored in the second water tank 103 through both the base layer 102 and the piping 120.

[0065] The shape of the pipe 120 is arbitrary, and may be uniformly formed as a vertical pipe, for example. Furthermore, as shown in FIG. 2, the ends of the pipe 120 may be parallel to the left-right direction, and the remaining parts may be parallel to the up-down direction. The rainwater storage device 100 may include a plurality of pipes 120. In such a case, the amount of rainwater drained from the first water tank 101 can be increased in proportion to the number of pipes 120.

[0066] In addition, in any embodiment, rainwater may be drained from the first water tank 101 to the second water tank 103. According to the above configuration, rainwater can be drained from the first water tank 101 to the second water tank 103. Therefore, regardless of whether the base layer 102 arranged between the first water tank 101 and the second water tank 103 has water permeability, rainwater can be drained from the first water tank 101 to the second water tank 103.

[0067] For example, the structure 110 may be formed by stacking the structural members 118 shown in Fig. 9, instead of the structural members 111 shown in Fig. 7 and Fig. 8. The structural members 118 include a protruding portion 118a and a bottom plate 118b. Like the structural members 111, the structural members 118 are preferably made of a thermoplastic resin.

[0068] The bottom plate 118b has a plate-like shape with a certain thickness, and is formed in a lattice pattern as shown in Fig. 9. Furthermore, the bottom plate 118b has a fitting portion 118c on its surface. The fitting portion 118c has an open upper portion. The fitting portion 118c is provided so as to be able to fit with the upper end of the protrusion portion 118a of another structural member 118 that is turned upside down.

[0069] As shown in Fig. 9, the protrusion 118a is cylindrical, and the inner diameter of the protrusion 118a decreases toward the upper end of the protrusion 118a. The protrusion 118a is open at the top and hollow inside. Therefore, rainwater can be stored inside the protrusion 118a. Two protrusions 118a are arranged diagonally on the bottom plate 118b.

[0070] A method of stacking the structural members 118 to construct the structure 110 will be described below. First, two structural members 118, 118 are turned upside down, and the protruding portion 118a of one structural member 118 is fitted into the fitting portion 118c of the other structural member 118 to form a pair of structural members 118, 118. The pair of structural members 118, 118 are then laid out in the front-rear and left-right directions, and stacked up and down to construct the structure 110.

[0071] Although Figure 9 shows a structural member 118 in which the bottom plate 118b is formed into a square shape and two protrusions 118a are arranged side by side in the front-to-back and left-to-right directions on this bottom plate 118b, the structure is not limited to this, and as described below, the structural member may have two or more rows of protrusions 118a arranged side by side in the front-to-back and left-to-right directions.

[0072] In addition, when the first foundation layer 102 or the second foundation layer 109 (hereinafter referred to as the foundation layers 102 and 109) is made of a material having water permeability such as crushed stone, the side and bottom surface, or only the bottom surface, may be wrapped with a water permeable sheet or the like, similar to the second water tank 103. In the rainwater storage device 100 of the present invention, the second water tank 103 provided below the foundation layer may be filled with water during heavy rain, causing rainwater to accumulate in the foundation layers 102 and 109. Therefore, the foundation layers 102 and 109 may become loose due to the buoyancy of the rainwater, or the crushed stone itself may rise to the water level and flow out. Furthermore, the crushed stone or the like presses the structure 110 of the second water tank 103 from above, preventing the structure 110 from floating up due to the buoyancy of the water. Therefore, when the crushed stone or the like flows out, the structure 110 may also float up due to the buoyancy of the water. Therefore, by wrapping the sides and bottom of the foundation layers 102, 109, or just the bottom, with a permeable sheet or the like, similar to the second water tank 103, it is possible to prevent the outflow of crushed stone and the like or the floating of the structure 110.

[0073] Furthermore, a plate-like member such as an iron plate may be installed between the ground layer 119 and the side surface of the second water tank 103 instead of the wall body 105. In the rainwater storage device 100 according to the present invention, two water tanks are installed in the ground layer 119. Therefore, compared with a rainwater storage device in which only one water tank is installed in the ground layer 119, the buried depth is deeper. Therefore, compared with the case in which only one water tank is installed in the ground layer 119, the horizontal earth pressure from the ground layer 119 on the structure 110 constituting the second water tank 103 becomes larger. In response to this, the horizontal earth pressure can be dispersed by installing the plate-like member such as the iron plate between the ground layer 119 and the second water tank 103. Therefore, the destruction of the structure 110 due to the horizontal earth pressure can be prevented.

[0074] In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described modified examples may be combined as appropriate.

[0075] (Additional Note) <1> A rainwater storage device according to one embodiment of the present invention comprises a first water tank having an open top and capable of storing rainwater, a foundation layer provided below the first water tank, and a second water tank provided below the foundation layer and capable of storing rainwater, wherein the second water tank comprises a structure having a structure in which a number of structural members are stacked, the structural members having a bottom plate and a number of protrusions and made of thermoplastic resin.

[0076] According to the above configuration, the rainwater storage device includes the first water tank and the second water tank. Therefore, by including these two water tanks in the rainwater storage device, it is possible to obtain a rainwater storage device that can store a large amount of rainwater. Furthermore, the second water tank has a structure in which a plurality of structural members are stacked. The structural member has a bottom plate and a plurality of protrusions, and is made of a thermoplastic resin. Therefore, for example, the second water tank can be formed by stacking the structural members, and construction is easier than the conventional technology in which a plurality of concrete blocks are used. Therefore, the heavy machinery required for construction can be minimized, and construction can be performed in a small space. Therefore, a rainwater storage device that can store a large amount of rainwater and is easy to construct can be obtained.

[0077] <2> the above <1> In the rainwater storage device according to the present invention, the base layer has water permeability.

[0078] According to the above configuration, the foundation layer has water permeability. Therefore, rainwater in the first water tank can permeate into the foundation layer and further into the second water tank. It is also possible for rainwater in the second water tank to permeate into the foundation layer and further into the first water tank. Therefore, for example, during normal rainfall other than heavy rain, rainwater in the first water tank can permeate into the foundation layer and further into the second water tank. Therefore, almost no rainwater accumulates in the first water tank. In contrast, an example of a conventional rainwater storage device is an open-type reservoir. An open-type reservoir is installed on the ground, and the top of the reservoir is open. In the case of an open-type reservoir, rainwater is often stored in the reservoir at all times, and since the open-type reservoir is an environment in which living things can easily grow, pests and birds and animals are likely to appear in the reservoir. In particular, in the case of an open-type reservoir installed near an airport, etc., birds flying in can cause bird damage and may even lead to airplane accidents. On the other hand, in the rainwater storage device, almost no rainwater accumulates in the first water tank during normal rainfall, so that the occurrence of pests and bird damage can be prevented. Furthermore, if rainwater seeps into the second water tank during heavy rain and exceeds the capacity of the second water tank, the rainwater in the second water tank will seep up and accumulate in the first water tank. After the rainwater is drained from the rainwater storage device, the first water tank will be in a state where there is almost no rainwater, just like during normal rainfall.

[0079] <3> the above <1> or <2> The rainwater storage device according to the present invention further includes a pipe through which the rainwater in the first water tank is drained to a lower portion of the second water tank.

[0080] According to the above configuration, rainwater can be treated not only by storing it in the first water tank, but also by discharging it to the lower part of the second water tank, thereby improving the rainwater treatment capacity.

[0081] <4> the above <1> ~ <3> In the rainwater storage device according to any one of the above aspects, rainwater can be drained from the first water tank to the second water tank.

[0082] According to the above configuration, rainwater can be drained from the first water storage layer to the second water storage tank. Therefore, regardless of whether the foundation layer arranged between the first water storage tank and the second water storage tank has water permeability, rainwater can be drained from the first water storage tank to the second water storage tank.

[0083] <5> the above <1> ~ <4> In the rainwater storage device according to any one of the above aspects, the first water tank covers at least a part of an upper portion of the second water tank.

[0084] According to the above configuration, the first water tank does not need to cover the entire upper part of the second water tank, but only needs to cover at least a part of the upper part of the second water tank. This increases the degree of freedom in the location and size of the second water tank, and increases the degree of freedom in construction.

[0085] <6> the above <1> ~ <5> The rainwater storage device according to any one of the above embodiments includes a third water tank arranged alongside the first water tank and capable of storing rainwater, the third water tank having a structure, the first water tank covering a portion of an upper part of the second water tank, the third water tank covering at least a portion of the remainder of the upper part of the second water tank, and the first water tank covering at least a portion of a side part of the third water tank.

[0086] According to the above configuration, the rainwater storage device may include a third water tank that is provided alongside the first water tank and can store rainwater. This increases the degree of freedom in terms of the location and size of the second water tank, and increases the degree of freedom in construction. Furthermore, the third water tank includes a structure. This allows rainwater to be stored directly in the structure in the third water tank. [Explanation of symbols]

[0087] 100 Rainwater storage device 101 First Water Tank 102 Base layer, 1st base layer 103 Second Water Tank 108 Third Water Tank 110 Structure 111 Structural members 112 Projection part 115 Bottom plate 120 Piping

Claims

1. A first water tank whose top is open and capable of storing rainwater; A base layer provided under the first water tank; A second water tank is provided under the foundation layer and capable of storing rainwater. The second water tank includes a structure having a structure in which a plurality of structural members are stacked, The structural member has a bottom plate and a plurality of protrusions, and is made of a thermoplastic resin. Rainwater storage device.

2. The rainwater harvesting device according to claim 1 , wherein the base layer is water permeable.

3. The rainwater storage device according to claim 1 or 2, further comprising a pipe for draining the rainwater in the first water tank to a lower portion of the second water tank.

4. The rainwater storage device according to claim 1 or 2, wherein rainwater can be drained from the first water tank to the second water tank.

5. The rainwater storage device according to claim 1 or 2, wherein the first water tank covers at least a part of an upper portion of the second water tank.

6. a third water tank arranged next to the first water tank and capable of storing rainwater; The third water tank includes the structure, The first water tank covers a part of an upper portion of the second water tank, The third water tank covers at least a portion of the remaining upper portion of the second water tank, The rainwater storage device according to claim 1 or 2, wherein the first water tank covers at least a part of a side of the third water tank.

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