Structural member for water storage tank and sand retention plate

Abstract

To provide a structural member for a water storage tank in which a sand retention plate attached thereto is unlikely to come off.SOLUTION: There is provided a structural member 20 for a water storage tank, which comprises a base 21 and a plurality of legs 22 erected on the base 21, and which is stacked in a juxtaposed state to ensure storage space for the water storage tank and form a juxtaposed stacked structure. A sand retention plate 40A can be attached between side surfaces 221 of the adjacent legs 22 out of the plurality of legs 22. An insertion groove 222 is formed in the side surfaces 221 of the adjacent legs 22, into which the sand retention plate 40A is inserted.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a structural member and a sediment retention plate for a water storage tank. [Background technology]

[0002] A rainwater storage facility is a facility for storing rainwater. To install a rainwater storage facility, a pit is dug in a road, park, parking lot, or a planned site, and multiple structural members are arranged horizontally and vertically. The surrounding area is then covered with a permeable or impermeable sheet and backfilled with soil. This rainwater storage facility has large internal gaps, so it can store rainwater. In addition, the arranged structural members can support the load of a facility constructed above. One such structural member has a base and multiple legs erected on the base, and further has a sand retention plate between adjacent legs to prevent soil and sand from entering the inside of the structural member (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7021385 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the sediment retention plate in Patent Document 1 has a flange that is curved so as to embrace the peripheral surfaces of the legs on both sides, and this side shape ensures a wide contact area between the sides of the legs and the sides of the sediment retention plate. However, because the sediment retention plate in Patent Document 1 is configured to be in surface contact with the legs, there is a risk that the sediment retention plate will come off the legs if the molded product is deformed due to shrinkage or warping, or if stress such as water pressure acts on the sediment retention plate after assembly.

[0005] Therefore, an object of the present invention is to provide a structural member for a water storage tank from which a sand retention plate is unlikely to come off once attached, and a sand retention plate that can be attached to a structural member for a water storage tank. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a structural component for a water storage tank which comprises a base and a number of legs erected on the base, and which is stacked in a juxtaposed state to secure storage space for the water storage tank, and in which a sand retention plate can be attached between the opposing surfaces of adjacent legs among the plurality of legs, and an insertion groove is formed in the opposing surfaces of the adjacent legs into which the sand retention plate can be inserted.

[0007] The insertion groove has a contact piece formed therein, the contact piece extending from a bottom surface thereof in a direction perpendicular to the bottom surface. Each of the legs has side surfaces on four sides, and the insertion groove is formed on each of the side surfaces.

[0008] The length between the opposing faces of the adjacent legs increases toward the tips of the legs. Also, there is provided a sand retention plate that can be attached between opposing surfaces of adjacent legs in a structural member for a water storage tank, which has a base and a number of legs erected on the base, and which is stacked in a juxtaposed state to secure storage space for the water storage tank and form a juxtaposed stacked structure by arranging a number of units in a juxtaposed stacked state, and the sand retention plate has an insertion portion that can be inserted into an insertion groove formed in the opposing surface of the legs.

[0009] The insertion portion is a rib portion that can be inserted into the insertion groove. Effect of the Invention

[0010] According to the present invention, even when a sand retention plate is attached to a structural member for a water storage tank, the sand retention plate is unlikely to come off. [Brief description of the drawings]

[0011] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] 5(a) is an end view of the portion 5a-5a in FIG. 4, FIG. 5(b) is an end view of the portion 5b-5b in FIG. 4, and FIG. 5(c) is a plan view of the leg portion. [Figure 6] Figure 6(a) is an oblique view of the first sediment retention plate, Figure 6(b) is a side view of the same, Figure 6(c) is a front view of the same, Figure 6(d) is a front view of the second sediment retention plate, Figure 6(e) is a front view of the third sediment retention plate, and Figure 6(f) is a front view of the fourth sediment retention plate. [Figure 7] 7(a), 7(b), and 7(c) are explanatory diagrams showing the assembly procedure. [Figure 8] Partial cross-sectional view of Figure 7(c). [Figure 9] 9(a), 9(b), and 9(c) are plan views showing modified examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of a juxtaposed laminated structure 10 embodying the present invention and a structural member 20 constituting the juxtaposed laminated structure 10 will be described with reference to Figs. 1 to 8. For ease of explanation, the directions of each component will be described on the assumption that the juxtaposed laminated structure 10 and the structural member 20 are installed on a horizontally formed floor surface, for example, a floor surface on which concrete has been poured. In addition, when there are multiple components, reference numerals may be used to refer to only some of them.

[0013] FIG. 1 shows a perspective view of a juxtaposed laminated structure 10. The juxtaposed laminated structure 10 is constructed by juxtaposing a plurality of structural members 20 in the horizontal direction and fitting and stacking an inverted structural member 20 on top of each structural member 20. Of these, a pair of structural members 20 stacked one above the other is called a unit member 30. A storage space for a water storage tank is secured inside the structural member 20, and thus a storage space for a water storage tank is secured inside the juxtaposed laminated structure 10. FIG. 1 shows a configuration in which three unit members 30, each of which is a pair of structural members 20 stacked one above the other, are stacked in layers. Furthermore, a sand retention plate 40 is attached to each of the lower and middle unit members 30.

[0014] Fig. 2 shows an exploded perspective view of a unit member 30 located at a lower corner of the juxtaposed stacked structure 10 shown in Fig. 1, and a sediment retention plate 40 attached thereto. As shown in Fig. 2, one unit member 30 is configured by stacking two structural members 20 by fitting them together in an opposing relationship above and below. The two upper and lower structural members 20 both have the same shape, and the upper structural member 20 is the lower structural member 20 turned upside down. For this reason, the lower structural member 20 will be described below, but this description also applies to the upper structural member 20 turned upside down when in use.

[0015] (Structural member 20) Fig. 3 shows a plan view of structural member 20, and Fig. 4 shows a side view of structural member 20. As shown in Fig. 3 and Fig. 4, structural member 20 has a base 21 having a generally rectangular shape in a plan view, and four legs 22 standing upward from the four corners of base 21. In structural member 20, base 21 and legs 22 are integrally molded from synthetic resin (including recycled materials) such as polypropylene.

[0016] (Base 21) As shown in FIG. 3, the base 21 is substantially square in plan view, and has four sides 23 on the periphery. Each side 23 has the same length, and adjacent sides 23 form a right angle in plan view, and opposing sides 23 are parallel in plan view. The corners of each side 23 are chamfered. As shown in FIG. 3 and FIG. 4, the base 21 is composed of a square frame portion 24 and a base body 25 integrally formed inside the frame portion 24, and the upper surface 25a of the base body 25 is located higher than the frame portion 24. The base 21 also has a plurality of vertical ribs 211 and a plurality of horizontal ribs 212. The outer edge of the frame portion 24 of the base 21 constitutes the side 23 of the structural member 20.

[0017] In the rectangular portion of the base 21 surrounded by the vertical ribs 211 and the horizontal ribs 212, a lightening hole 213 is formed that penetrates in the vertical direction. The purpose of this lightening hole 213 is to reduce the weight of the structural member 20 and ensure the flow of water inside the structural member 20. Note that the lightening holes 213 are basically substantially rectangular, but some of them, which are located on the base body 25 adjacent to the side 23 extending vertically in Fig. 3, are marker lightening holes 214 formed in a pentagonal shape with their tips facing outward (left-right direction in the figure) from the frame portion 24. This serves as a marker for aligning the orientation of the structural members 20 when fitting the structural members 20 vertically to form the unit member 30.

[0018] 3 and 4, legs 22 are formed on the inside of the frame 24 of the base 21 at the four corners of the base body 25, and stand upward. All four legs 22 have the same shape, and are different only in their positions on the base 21. For this reason, one leg 22 will be specifically described, and this description also applies to the other three legs 22.

[0019] (leg 22) Leg 22 is hollow and has a basic shape of a quadrangular pyramid (rectangular pyramid). Leg 22 has side surfaces 221 in each of the four directions. The four side surfaces 221 formed on leg 22 have the same shape except for the shape of the tip. Below, one side surface 221 will be explained, but the explanation also applies to the other three side surfaces 221 of leg 22.

[0020] 4 and 5, side surface 221 of leg portion 22 is a trapezoid whose width (left and right in FIG. 5) narrows toward the top, and since leg portion 22 is a quadrangular pyramid shape, side surface 221 is inclined toward the center of leg portion 22 at a certain angle with respect to the vertical direction. Also, side surface 221 has an insertion groove 222 with a concave cross section formed over the entire height direction of leg portion 22. Insertion groove 222 has two parallel side walls 223 and a bottom surface 224 continuous with side walls 223.

[0021] As shown in Figs. 5(a), (b), and (c), the width of the insertion groove 222 (left and right in Fig. 5) is constant throughout the height direction of the leg 22. The width of the insertion groove 222 is the length between the two side walls 223 and also the width of the bottom surface 224. The insertion groove 222 is formed at the center of the side surface 221 in the width direction, and the center of the insertion groove 222 in the width direction coincides with the center of the side surface 221 of the leg 22 in the width direction. The depth of the insertion groove 222 is constant throughout the height direction of the leg 22 and is shorter than the width of the insertion groove 222. The depth of the insertion groove 222 is the depth of the two side walls 223 and is also the length from the side surface 221 to the bottom surface 224. That is, as shown in Figs. 5(a) and 5(b) showing the end faces of the leg 22, the width of the side surface 221 of the leg 22 narrows upward, but the width and depth of the insertion groove 222 are both constant in the height direction.

[0022] 3 to 5, a thin plate-like abutment piece 225 is formed on the bottom surface 224 of the insertion groove 222 over the entire height direction of the insertion groove 222. The abutment piece 225 extends from the center of the width direction of the bottom surface 224 perpendicular to the bottom surface 224 and parallel to the side wall 223. The lower end of the abutment piece 225 is connected to the base 21. The protruding length of the abutment piece 225 perpendicular to the bottom surface 224 is constant over the entire height direction and is about 1 / 3 times the depth of the insertion groove 222.

[0023] As shown in Fig. 4 and Fig. 5(c), a fitting portion 226 is formed at the tip, which is the upper end of the leg portion 22. This fitting portion 226 is a portion that fits the upper and lower legs 22 when two structural members 20 are fitted together by facing each other vertically. As described above, one leg portion 22 has four side surfaces 221, and an insertion groove 222 is formed in each of these four side surfaces 221. Then, at the tip of the leg portion 22, a portion including two corners, the lower left corner and the upper right corner in Fig. 5(c), among the four corners of the leg portion 22, is extended upward by a certain height from the other two corners. Specifically, for the lower left corner and the upper right corner in Fig. 5(c), a range that connects the fronts of the contact pieces 225 formed in the respective insertion grooves 222 of the two side surfaces 221 that sandwich these corners in an arc shape is extended upward. As a result, the fitting portion 226 at the tip of the leg 22 is formed as a fitting protrusion 226a that is extended upward at a portion including two diagonal corners, and a portion including the other diagonal corners is formed as a fitting recess 226b that is relatively lower than the fitting protrusion 226a. When the structural member 20 is placed facing each other up and down, the legs 22 also face each other, and the fitting protrusions 226a and the fitting recesses 226b are fitted together to form the unit member 30. In order to prevent interference between the fitting protrusions 226a, the area of ​​the fitting recess 226b in a plan view is formed to be larger than the fitting protrusions 226a. In addition, a circular hole 226c is formed inside each corner on the top surface of the tip of the leg 22, and the inside and outside of the leg 22 are communicated through the circular hole 226c.

[0024] (Relationship between the four legs 22 of the structural member 20) 4, the legs 22 are in the shape of a quadrangular pyramid, and the length between the side surfaces 221 (left and right in FIG. 4), which are the opposing surfaces of two adjacent legs 22, increases toward the tips of the legs 22. The length between the bottom surfaces 224 of both insertion grooves 222 formed on the opposing side surfaces 221, and the length between the opposing abutment pieces 225 also increase toward the tips of the legs 22.

[0025] 3, the four legs 22 formed on the base 21 are formed so that the intervals between adjacent legs 22 in a direction parallel to the side 23 of the base 21 are equal. Furthermore, in two legs 22 adjacent in a direction parallel to the side 23 of the base 21, the two side surfaces 221 positioned parallel to the side 23 are positioned on the same plane.

[0026] (Sediment retention plate 40) Fig. 6(a) shows a perspective view of the first sediment retention plate 40A as the sediment retention plate 40, Fig. 6(b) shows a side view of the same, and Fig. 6(c) shows a front view of the same. As shown in these figures, the first sediment retention plate 40A has a hexagonal shape that is widest at the center in the height direction when viewed from the front. The first sediment retention plate 40A has no distinction between top and bottom or front and back, so it has the same shape even if it is turned upside down or front and back from the state shown in Fig. 6(c).

[0027] The first sand accumulation plate 40A is made of a hexagonal plate-shaped face plate 41A (41) and a hexagonal frame-shaped rib portion 42A (42) surrounding the face plate 41A, which is an insertion portion, and is integrally formed from a synthetic resin (including recycled materials) such as polypropylene. The rib portion 42A can be inserted into the insertion groove 222. The height of the first sand accumulation plate 40A, face plate 41A, and rib portion 42A refers to the vertical direction in Figs. 6(a) to 6(c). The width refers to the left-right direction in Fig. 6(c), and the thickness refers to the left-right direction in Fig. 6(b). The face plate 41A is a plate-shaped hexagon with a constant thickness. The surface of the face plate 41A is formed flat, and no through holes are formed. A convex line 43A (43) is formed at the center of the face plate 41A in the height direction, where the face plate 41A is at its widest, connecting both widthwise ends.

[0028] The rib portion 42A is a strip-shaped portion formed perpendicularly to the face plate 41A. The rib portion 42A fits around the face plate 41A along the outer periphery of the face plate 41A, and the two are formed integrally. The rib portion 42A has upper and lower pieces 44A (44) located at the upper and lower ends and extending in the horizontal direction, and has dogleg-shaped inclined pieces 45A (45) connected to both ends of both the upper and lower pieces 44A. Therefore, the rib portion 42A has a hexagonal frame shape as a whole when viewed from the front. The rib portion 42A is formed to a constant thickness, which is slightly shorter than the width of the insertion groove 222 formed in the leg portion 22. The face plate 41A is connected to the center of the thickness of the rib portion 42A.

[0029] The height of the first sediment retention plate 40A, i.e., the height of both upper and lower pieces 44A, is the same as the vertical length between the upper surfaces of the base body 25 when two structural members 20 are fitted together vertically to form the unit member 30. The width of the first sediment retention plate 40A, i.e., the length between the left and right outer ends of the pair of inclined pieces 45A, varies in the height direction as shown in FIG. 6(c). However, when the first sediment retention plate 40A is attached between the adjacent legs 22, the pair of inclined pieces 45A are inserted into the opposing insertion grooves 222. That is, the length between the left and right outer ends of the pair of inclined pieces 45A is longer than the length between the opposing side surfaces 221 when the first sediment retention plate 40A is attached between the adjacent legs 22, and shorter than the length between the opposing abutment pieces 225. The inclination angle of the inclined pieces 45A with respect to the vertical direction is the same as the inclination angle of the insertion groove 222 formed in the side surface 221 of the leg 22 with respect to the vertical direction.

[0030] FIG. 6(d) shows a front view of the second sediment retention plate 40B as the sediment retention plate 40. The second sediment retention plate 40B is different from the first sediment retention plate 40A only in that the face plate 41B of the second sediment retention plate 40B has a plurality of water circulation holes 46B (46) penetrating in the thickness direction, and other explanations will be omitted. For convenience of explanation, the configuration of the second sediment retention plate 40B is numbered with a suffix B, but unless otherwise specified, it is the same as the configuration of the first sediment retention plate 40A with an A suffix. The second sediment retention plate 40B has a plurality of water circulation holes 46B penetrating vertically and line-symmetrically with respect to the convex line 43B of the face plate 41B. Each water circulation hole 46B is formed as a long hole that is long in the horizontal direction, and is used to circulate water in the thickness direction across the second sediment retention plate 40B. There are no particular restrictions on the opening area of ​​each water circulation hole 46B and the total opening area of ​​the water circulation holes 46B formed in the second sediment accumulation plate 40B. In this embodiment, the opening area of ​​each water circulation hole 46B is smaller than the opening area of ​​the largest lightening hole 213. In addition, the total opening area of ​​the water circulation holes 46B formed in the second sediment accumulation plate 40B is smaller than the total opening area of ​​the lightening holes 213 formed in the base body 25.

[0031] FIG. 6(e) shows a front view of the third sediment retention plate 40C as the sediment retention plate 40. The third sediment retention plate 40C differs from the first sediment retention plate 40A only in its width, and other explanations will be omitted. The components of the third sediment retention plate 40C are numbered with a suffix C, but unless otherwise specified, the components are the same as the other components. The third sediment retention plate 40C is disposed between the legs 22 (see FIG. 1) that are erected facing each other between two adjacent structural members 20 when the structural members 20 are horizontally disposed adjacent to each other. The width of the upper and lower pieces 44C of the rib portion 42C (left and right in FIG. 6(e)) is longer than the distance between the opposing side surfaces 221 of the two adjacent legs 22 across the two structural members 20 when the two structural members 20 are disposed side by side in abutment with each other, and shorter than the distance between the opposing abutment pieces 225. Therefore, when the third sand retention plate 40C is attached between two adjacent structural members 20, a pair of inclined pieces 45C of the rib portion 42C of the third sand retention plate 40C are inserted into the insertion grooves 222 formed in the opposing leg portions 22 between the two adjacent structural members 20.

[0032] 6(f) shows a front view of a fourth sediment retention plate 40D as one of the sediment retention plates 40. The fourth sediment retention plate 40D differs from the third sediment retention plate 40C only in that a plurality of water circulation holes 46D are formed in the face plate 41D, penetrating in the thickness direction, and the rest is the same. The components of the fourth sediment retention plate 40D are numbered with a suffix D, but unless otherwise specified, the components are the same as the other components.

[0033] (Formation of juxtaposed laminate structure 10) Next, a procedure for assembling the structural member 20 and the sand retention plate 40 of this embodiment to form the juxtaposed laminated structure 10 will be described.

[0034] As shown in Fig. 7(a), the base 21 is placed on the floor with the leg 22 of one structural member 20 facing upward. Next, as shown in Fig. 7(b), a first sand accumulation plate 40A is attached from above between the leg 22 erected at the front corner of the base 21 and the opposing side surface 221 of the adjacent leg 22. The lower half of each first sand accumulation plate 40A in the height direction is attached to the leg 22.

[0035] 7(c), the upside-down structural member 20 is placed over the lower structural member 20 from above, so that the legs 22 fit together, and the upper half of the first sediment retention plate 40A is fitted between the two legs 22 of the upper structural member 20 from above. When placing the structural member 20 over the lower structural member 20, the orientation of the marker lightening hole 214 shown in FIG. 3 is aligned with the orientation of the marker lightening hole 214 of the lower structural member 20. Then, the mating protrusions 226a and mating recesses 226b (see FIG. 4) formed on the upper and lower opposing legs 22 fit together. This allows a configuration in which two of the four side surfaces of the unit member 30 are covered with the first sediment retention plate 40A.

[0036] In this state, as shown in FIG. 8, the inclined pieces 45A of the rib portion 42A of the first sediment retention plate 40A are inserted into the insertion grooves 222 of the legs 22. Note that the interior of the legs 22 is not shown in FIG. 8. The width (left and right in FIG. 6(c)) of the rib portion 42A of the first sediment retention plate 40A is shorter than the length between the opposing abutment pieces 225 at the same position. Therefore, the rib portion 42A is in a state where it does not abut against both of the opposing abutment pieces 225 or is in a state where it abuts against only one of the opposing abutment pieces 225. FIG. 8 illustrates a state where it does not abut against both of the opposing abutment pieces 225. Then, a juxtaposed laminated structure 10 can be formed by arranging a plurality of unit members 30 to which the first sediment retention plate 40A is attached in a state where they abut against each other in the horizontal and vertical directions as shown in FIG. In the above procedure, one lower structural member 20 is installed, the first sediment retention plate 40A is attached, and then the inverted structural member 20 is placed over the unit members 30. That is, the unit members 30 are formed one by one and arranged in the horizontal direction to form the juxtaposed stacked structure 10. However, the procedure is not limited to this. For example, first, a plurality of lower structural members 20 are arranged in the horizontal direction, the first sediment retention plate 40A is attached to these structural members 20, and each structural member 20 is then covered with the inverted structural member 20 from above. In this way, the juxtaposed stacked structure 10 may be formed by forming a plurality of unit members 30, so to speak, simultaneously, and the procedure is not limited to this.

[0037] In FIG. 1, the lower tier of unit members 30 has three upper and lower tiers, and a first sediment retention plate 40A with no through holes formed in the face plate 41A is used to prevent the inflow of sediment. The middle tier has a second sediment retention plate 40B with water flow holes 46B formed therein, since the inflow of sediment is relatively small. Furthermore, the unit member 30 installed in the upper tier does not have a sediment retention plate 40 attached. In FIG. 1, a third sediment retention plate 40C is used between the legs 22 erected opposite to each other between two horizontally adjacent unit members 30 in the lower tier of the three upper and lower tiers. A fourth sediment retention plate 40D is attached to the same location in the middle tier. Furthermore, a sediment retention plate 40 is not attached to the same location in the upper tier.

[0038] These are examples of the use of multiple types of sand retention plates 40, and it is possible to determine appropriately which type of sand retention plate 40 to use in which location on the unit member 30, or whether or not to use it at all, depending on the usage situation.

[0039] According to the juxtaposed stacked structure 10 of the above embodiment, the following effects can be obtained. (1) In the above embodiment, the insertion grooves 222 are formed in the opposing side surfaces 221 of the adjacent leg portions 22, and the rib portion 42A of the first sediment retention plate 40A is inserted into the insertion grooves 222 to attach the sediment retention plate 40 to the structural member 20 and the unit member 30. Since the rib portion 42A of the first sediment retention plate 40A is inserted into the insertion grooves 222, assembly defects due to deformation of the structural member 20 or the first sediment retention plate 40A are unlikely to occur. Furthermore, even if water pressure is applied to the first sediment retention plate 40A and the face plate 41A, etc. are deformed, the rib portion 42A is unlikely to come off the insertion grooves 222, and the attachment of the structural member 20 and the unit member 30 to the first sediment retention plate 40A is unlikely to come off.

[0040] (2) An abutment piece 225 is formed in the insertion groove 222. When the rib portion 42A of the first sediment retention plate 40A inserted in the insertion groove 222 is inserted into the insertion groove 222 or when the rib portion 42A moves within the insertion groove 222, it abuts against the abutment piece 225 without coming into contact with the bottom surface 224 of the insertion groove 222. When the rib portion 42A of the first sediment retention plate 40A comes into contact with the bottom surface 224 of the insertion groove 222, it becomes surface contact and the resistance becomes large, but it becomes line contact with the abutment piece 225 and the contact resistance becomes small. For this reason, the rib portion 42A can easily move within the insertion groove 222 during or after the insertion of the rib portion 42A into the insertion groove 222.

[0041] (3) The structural member 20 has four legs 22 arranged at equal intervals in a rectangular shape. The legs 22 are shaped like a truncated pyramid. The legs 22 have side surfaces 221 on all four sides, and an insertion groove 222 is formed in each side surface 221. There are four locations in one structural member 20 where the sediment retention plate 40 can be attached between adjacent legs 22, and a common sediment retention plate 40 can be used for all of them, which reduces restrictions on the orientation of the structural member 20.

[0042] (4) The sand retention plate 40 is formed in a symmetrical shape so that it has the same shape even when turned upside down. Therefore, there is no restriction on the orientation of the sand retention plate 40 when it is used, making it easy to use.

[0043] (5) The sand retention plate 40 has a rib portion 42, and this rib portion 42 is inserted into the insertion groove 222. This makes it easy to attach the sand retention plate 40 to the insertion groove 222. (6) The width of the sand retention plate 40 is longer than the length between the opposing side surfaces 221 when installed, and shorter than the length between the opposing contact pieces 225. Furthermore, the thickness of the rib portion 42 of the sand retention plate 40 is slightly shorter than the width of the insertion groove 222 formed in the leg portion 22. For this reason, there are gaps between the rib portion 42 of the sand retention plate 40 and the insertion groove 222 and between the contact piece 225 and the sand retention plate 40, allowing the flow of water. As a result, even when the sand retention plate 40 is installed on the structural member 20, the flow of water is not completely blocked.

[0044] (7) When the face plate 41A of the first sediment retention plate 40A is deflected by water pressure, the face plate 41A is curved. As a result, the rib portion 42A formed integrally with the face plate 41A is also inclined with respect to the bottom surface 224 of the insertion groove 222, so that the gap between the rib portion 42A and the insertion groove 222 and between the rib portion 42A and the contact piece 225 becomes larger, and water can easily flow.

[0045] The above embodiment may be modified as follows. Although the structural member 20 has been configured to have two legs 22 parallel to the side 23, this is not limited to the above. For example, three legs 22 may be arranged at equal intervals parallel to the side 23. In this case, if the base 21 is square in plan view, there are three legs 22 parallel to one side 23, so that nine legs 22 (3 x 3) are formed on the base 21, and there are twelve locations where the sediment retention plates 40 can be installed between adjacent legs 22. Four or more legs 22 may be formed parallel to one side 23.

[0046] Furthermore, when the base 21 is formed into a rectangular shape in a plan view, the lengths of the sides 23 do not have to be the same. For example, the base 21 may be formed into a rectangular shape in a plan view consisting of short sides and long sides, with two legs 22 provided in a direction parallel to the short sides and three legs 22 provided in a direction parallel to the long sides.

[0047] As shown in Fig. 9(a), two structural members 20 of the above embodiment may be joined together to form one structural member 20A. In this case, the long sides 23a of the structural member 20A are twice as long as the sides 23 of the structural member 20 of the above embodiment, and four legs 22 are formed in a direction parallel to the long sides 23a. The spacing between the two inner legs 22 of the four legs 22 is different from the spacing between the other legs 22. For this reason, a third sediment retention plate 40C or a fourth sediment retention plate 40D shown in Fig. 6(e) or Fig. 6(f) is used between the two inner legs 22.

[0048] As shown in Fig. 9(b), when two structural members 20 of the above embodiment are joined together to form one structural member 20B, another side than that shown in Fig. 9(a) may be a long side 23b twice as long as that of the above embodiment, and four legs 22 may be formed in a direction parallel to the long side 23b. In this case as well, the third sediment retention plate 40C or the fourth sediment retention plate 40D shown in Fig. 6(e) or Fig. 6(f) may be used between the two inner legs 22 out of the four.

[0049] As shown in Fig. 9(c), four structural members 20 of the above embodiment may be connected in a square shape to form a single structural member 20C. In this case, the structural member 20C has four legs 22 parallel to each side 23c. Of these, the two inner legs 22 use the third sand retention plate 40C or the fourth sand retention plate 40D shown in Fig. 6(e) or Fig. 6(f).

[0050] Although one abutment piece 225 is formed in one insertion groove 222, two or more abutment pieces 225 may be provided. Also, the abutment pieces 225 may be formed intermittently rather than continuously in the height direction of the insertion groove 222.

[0051] Although the insertion groove 222 formed on each side surface 221 is a single recess, it may be two parallel recesses. In this case, the mounting portion 42 of the sand retention plate 40 is also changed to a shape that matches the shape of the insertion groove 222.

[0052] Although the method of mounting the sediment retention plate 40 between the legs 22 has been described above by mounting the plate 40 from the tip of the legs 22, the plate 40 may be mounted from another direction by utilizing the elasticity of the plate 40. For example, the plate 40 is curved in the width direction to reduce its apparent width, and is inserted between the insertion grooves 222 from the side between the legs 22 (the direction perpendicular to the paper surface of FIG. 4). Then, the plate 40 may be released from its curvature and allowed to return to its original shape by its elasticity.

[0053] The rib portion 42 of the sediment retention plate 40 is a band-shaped portion formed perpendicular to the face plate 41, and is shaped to go around the outer periphery of the face plate 41, but is not limited to this. For example, it may be formed on part of the outer periphery of the face plate 41, and the thickness may vary in the circumferential direction. Also, the upper and lower pieces 44 may not be formed, and may be omitted in whole or in part.

[0054] Although the width of the insertion groove 222 (left and right in FIG. 5) is constant over the entire height direction of the leg portion 22, the width may be configured to vary in the height direction. Although the insertion groove 222 is formed at the center in the width direction of the side surface 221, it may be formed at a position shifted from the center in the width direction.

[0055] Although the contact piece 225 is formed over the entire height of the insertion groove 222, it may be formed over, for example, half or two-thirds of the length in the height direction. [Explanation of symbols]

[0056] 10...Parallel stacked structure 20...Structural members 21… Foundation 22...legs 30...Unit component 40(40A, 40B, 40C, 40D)…Sediment retention plate 42…Rib section (attachment section) 221...Side (opposing surface) 222…Insertion groove 224…Bottom 225...Abutment piece

Claims

1. A structural member for a water storage tank, comprising a base and a plurality of legs erected on the base, and a plurality of the structural members being stacked in a juxtaposed state to secure a storage space for the water storage tank, forming a juxtaposed stacked structure, A sand retention plate can be attached between opposing surfaces of adjacent legs among the plurality of legs, A structural member for a water storage tank, wherein an insertion groove for inserting the sediment retention plate is formed on the opposing surfaces of the adjacent legs.

2. 2. A structural member for a water storage tank according to claim 1, wherein said insertion groove has a contact piece formed therein, said contact piece extending from a bottom surface of said insertion groove in a direction perpendicular to said bottom surface.

3. 2. A structural member for a water storage tank according to claim 1, wherein each of said legs has side surfaces on four sides, and said insertion groove is formed on each of said side surfaces.

4. 2. A structural member for a water storage tank according to claim 1, wherein the length between the opposing faces of the adjacent legs increases toward the tips of the legs.

5. A sand retention plate that can be attached between opposing surfaces of adjacent legs in a structural member for a water storage tank, the structural member comprising a base and a plurality of legs erected on the base, the plurality of legs being stacked side by side to ensure a storage space for the water storage tank, the stacked structure being configured by stacking the plurality of legs side by side, The sand retention plate has an insertion portion that can be inserted into an insertion groove formed on the opposing surface of the leg.

6. The sand retention plate according to claim 5 , wherein the insertion portion is a rib portion that can be inserted into the insertion groove.

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