JP6239404B2 - Rainwater storage facility - Google Patents

Description

  The present invention relates to a rainwater storage facility provided under a ground such as a park, a parking lot, or a road in order to store a large amount of rainwater generated during heavy rain.

  Rainwater that falls on residential areas and roads is discharged into rivers through side ditches and drainage grooves with little penetration into the ground, but if a large amount of rainfall such as torrential rain occurs in a short time, Flooding causes traffic paralysis. For this reason, a rainwater storage facility is provided under the ground such as parks, parking lots, or roads, and when a large amount of rain occurs, the rainwater is temporarily stored in the rainwater storage facility through a side ditch or a drainage ditch. It is done.

  As such a rainwater storage facility, for example, as described in Patent Document 1, a filling block having an internal space for storing rainwater is laid vertically and horizontally in a water storage recess formed by digging the ground. A water storage tank that becomes a rainwater storage space is formed by stacking in multiple stages in the vertical direction, and this water storage tank is covered with sheet material, paving material, etc. and a rainwater inflow tank is provided outside the water storage tank. The rainwater is taken into the rainwater inflow trough through the gutter and the inflow pipe, and introduced into the water storage tank through the pipe from the rainwater inflow trough.

  The rainwater is mixed with earth and sand (hereinafter referred to as earth and sand), and when the earth and sand flows into the water tank together with the rain water, the volume of the water that can be stored is reduced by sedimentation and accumulation at the bottom of the water tank. In addition, there is a possibility that the drain pipe and the like are clogged, and it is difficult to remove the sediment deposited on the bottom of the water storage tank.

  For this reason, in the above-mentioned Patent Document 1, a rainwater inflow space is provided in a part of the water storage tank, the periphery of which is partitioned by a soil and sand capturing wall made of a soil and sand capturing sheet such as a woven fabric and a nonwoven fabric that captures soil and sand mixed in rainwater. At the same time, a work space not provided with the filling block is formed at the center of the rainwater inflow space, and by introducing rainwater into the rainwater inflow space surrounded by the soil trapping wall, the soil and sand mixed in the rainwater is removed. It settles at the bottom of the rainwater inflow space, drains it with the rainwater through the sediment discharge groove formed at the bottom of the rainwater inflow space, and discharges it to the orifice basin adjacent to the water storage tank. It is configured to periodically suck and remove the accumulated sediment.

  Further, in Patent Document 2, rainwater storage unit members having an internal space for storing rainwater are laid vertically and horizontally in a water storage recess formed by digging the ground, and stored in a plurality of stages in the vertical direction. While forming a water storage tank, a space part where the rainwater storage unit member is not provided is provided in a part of the water storage tank, and a water-permeable sheet is stretched in all directions in the space part. A filtration and precipitation tank is formed by inserting and installing a rectangular parallelepiped opening frame, and rainwater is allowed to flow into the filtration and precipitation tank, and sediment contained in the rainwater is precipitated at the bottom of the filtration and precipitation tank. On the other hand, a rainwater storage facility configured to discharge rainwater filtered by a water-permeable sheet to the outside through a water storage tank is described.

JP 2011-236692 A JP 2012-162896 A

  However, according to the former rainwater storage facility, part of the rainwater containing the earth and sand introduced into the rainwater inflow space is formed at the bottom of the rainwater inflow space without passing through the earth and sand catching sheet. It will be discharged together with earth and sand through the discharge groove to the side of the orifice basin, and not only will it not be possible to effectively display the rainwater filtering function by the capture sheet, but also the fineness contained in the rainwater introduced to the side of the orifice basin. There is a possibility that the earth and sand will be discharged to the river etc. through the drain pipe etc. without sinking.

  Furthermore, it is necessary to remove the sediment deposited at the bottom of the rainwater inflow space together with the sediment deposited at the bottom of the orifice dredging, and sediment also accumulates in the sediment discharge groove that leads from the bottom of the rainwater inflow space to the orifice dredging. As a result, not only does the removal work become difficult, but the earth and sand discharge grooves are clogged by the accumulated earth and sand, making it impossible to smoothly discharge rainwater in the water storage tank.

  On the other hand, according to the latter rainwater storage facility, a rectangular parallelepiped opening in which a space portion where the rainwater storage unit member is not provided is provided in a part of the water tank and a water-permeable sheet is stretched in all directions in the space portion. Since the frame is inserted and installed, if the perimeter of the opening frame is increased in order to increase the filtration capacity of the water permeable sheet, it is strong enough to withstand the load applied to the upper end of the opening frame. This makes it difficult to do this, and inevitably, only the installation of an opening frame with a short perimeter can be performed, resulting in a decrease in the water transmission capacity, which makes it impossible to employ it in a large-scale rainwater storage facility.

  The present invention has been made in view of such a problem, and the object of the present invention is to allow the earth and sand contained in the rainwater to flow into a predetermined location in the water tank even if there is a large amount of rainwater flowing into the water tank. It is an object of the present invention to provide a rainwater storage facility that can be separated from rainwater reliably and efficiently, and only rainwater can be smoothly discharged from the water tank to the outside, and earth and sand separated from rainwater can be easily recovered and removed.

  In order to achieve the above object, a rainwater storage facility according to the present invention includes a rainwater storage unit member having an internal space for storing rainwater in a water storage recess formed by excavating the ground. In a rainwater storage facility in which a water storage tank is formed by laying on and stacking in a plurality of stages and the upper surface of the water storage tank is covered with a covering material, the uppermost rainwater storage unit member is attached to a part of the water storage tank. A plurality of upper-stage rainwater storage unit member stacks having a depth reaching the lower-stage rainwater storage unit member row below the plurality of stages and stacked on the upper surface from the upper surface of the lower-stage rainwater storage unit member row An earth and sand settling tank part is provided by enclosing the part with a water-permeable sheet, and a manhole is formed in the earth and sand settling tank part. Characterized in that it provided a rainwater discharge pipe for discharging the rainwater to the outside from the lower end of the reservoir along with are provided rainwater inlet pipe for introducing the rainwater.

  In the rainwater storage facility configured as described above, the invention according to claim 2 is a lower stage in which a permeable sheet is laid on the upper surface of a part of the stormwater storage unit member laminated portion surrounded by the permeable sheet. A manhole having a width in the plane direction corresponding to the area of one rainwater storage unit member is formed by removing even the rainwater rainwater storage unit member, and a row of rainwater vertically and horizontally around the manhole. The rainwater storage unit member laminated portion is formed by stacking the storage unit members in the vertical direction.

  According to a third aspect of the present invention, in the manhole, there are four struts extending along the four corners of the manhole, and the struts are in contact with the four corners at regular intervals in the length direction of the pillars. A rectangular frame member made up of a rectangular frame member attached every time is inserted and disposed, and an elevating scaffolding frame member is attached to the rectangular frame member.

  The invention according to claim 4 is a preferred structure of the rainwater storage unit member, wherein a rectangular quadrangular truncated pyramid having a fixed height and having a lower end penetrating through the bottom plate and opening downward is provided in the front, rear, left and right. When the rainwater storage unit members are stacked vertically while intersecting at a right angle, the lower ends of both side inclined wall plate portions of the hollow quadrangular pyramid in the upper rainwater storage unit member are The lower rainwater storage unit member corresponding to the truncated pyramid is configured to be supported on the upper surfaces of both ends in the length direction of the top plate portion of the hollow quadrangular pyramid.

  The invention according to claim 5 is characterized in that the rainwater introduction pipe is piped from the outside of the water storage tank through the space portion between the opposed inclined wall plate portions of the adjacent hollow square pyramid in the rainwater storage unit member of the water storage tank. .

  Further, in the invention according to claim 6, in place of the rainwater storage unit member disposed around the bottom of the manhole in the sediment sedimentation tank, the bottom plate is gently inclined downward toward the bottom of the manhole, It is characterized in that a rainwater storage and sediment guidance unit member having a sediment guidance inclined surface guided to the manhole side is provided.

  Furthermore, the invention which concerns on Claim 7 is provided with the filtration precipitation tank part in several places of a water storage tank, and is comprised so that rainwater may be introduce | transduced into these filtration precipitation tank parts from the outside through a rainwater introduction pipe | tube from the outside, respectively. It is characterized by that.

  The invention according to claim 8 is configured such that a sand settling tank is provided in the ground adjacent to the water storage tank to receive rainwater from a side ditch or a drain ditch, and rainwater is introduced from the sand settling tank into the manhole through the rainwater introduction pipe. It is characterized by being.

  According to the first aspect of the present invention, the rainwater storage unit members are arranged vertically and horizontally, and a part of the water tank is stacked in multiple stages, and the lower-stage rainwater storage below the plurality of stages from the uppermost rainwater storage unit member. A plurality of upper-stage rainwater storage unit member stacking portions that have a depth reaching the unit member row and are stacked on the upper surface from the upper surface of the lower-stage rainwater storage unit member row are surrounded by a water-permeable sheet. A sedimentation tank is provided and a manhole is formed in the sedimentation tank. A rainwater introduction pipe for introducing rainwater from outside the water storage tank is provided in the manhole. Permeable sea that surrounds the laminated part of the permeable sheet that is arranged around the manhole and the permeable sheet that arranges all the rainwater introduced into the sediment sediment tank. The sediment contained in the rainwater can be captured by the water permeable sheet, and only the rainwater from which the sediment has been removed is disposed on the lower rainwater storage unit member side and the sediment sediment layer portion below the sediment sediment tank section. Can flow into and stay in the rainwater storage unit around the basin, smoothing rainwater from the water tank without causing sediment to accumulate on the bottom of the water tank, etc., and clogging the rainwater lead-out pipe It can be discharged.

  In addition, after draining rainwater in the water tank, maintenance and inspection can be performed through the manhole, and jet water is injected from the manhole through the gaps between the surrounding rainwater storage unit members, so that the permeable sheet The clogging and the like can be eliminated by washing the soil, and the sediment accumulated in the bottom of the sediment sedimentation tank can be flowed into the bottom of the manhole to easily collect and remove the sediment.

  Further, since the water permeable sheet is stretched so as to surround the peripheral surface of the rainwater storage unit member laminated portion in the sediment sedimentation tank section from the bottom of the sediment sedimentation tank section, the stretched area of the entire sheet can be widened. As a result, the filtration capacity is increased, and a large amount of rainwater containing earth and sand can be filtered, thereby providing a large-scale rainwater storage facility.

  According to the invention of claim 2, the manhole provided in a part of the rainwater storage unit member laminated portion surrounded by the water permeable sheet has an area in the plane direction corresponding to the area of one rainwater storage unit member. Therefore, a manhole that has a relatively narrow opening width and can sufficiently withstand a load from above can be formed.

  According to the invention of claim 3, in the manhole, there are four support posts that extend along the four corners of the manhole, and these support pillars are in contact with the four corners in the length direction of the support pillars. Since a rectangular frame consisting of rectangular frames attached at regular intervals is inserted and arranged, the shape of the manhole can be accurately maintained by this rectangular frame, and even if an earthquake occurs, the area around the manhole The rainwater storage unit member laminated portion can be supported in a stable state at a predetermined position without causing reluctance. In addition, since the lifting frame material is attached to the rectangular frame, inspection work by an operator can be easily performed.

  According to the invention of claim 4, the rainwater storage unit member is provided with a rectangular quadrangular truncated pyramid having a predetermined height and having a lower end penetrating the bottom plate and opening downward. In addition, when the rainwater storage unit members are stacked vertically while intersecting at right angles, the lower ends of both side inclined wall plate portions of the hollow square frustum in the upper rainwater storage unit member are connected to the hollow square frustums. Since the corresponding bottom rainwater storage unit member is configured to be supported on the upper surface of both ends in the longitudinal direction of the top plate portion of the hollow quadrangular pyramid, a plurality of rainwater reservoirs are formed when the water storage tank is formed. The unit member can be loaded easily and accurately and can be stably stacked. Of course, there is very little overlap between the rainwater storage unit members stacked one above the other, and the rainwater storage porosity is low. It is possible to form a large water tank.

  According to the invention which concerns on Claim 5, since the rainwater introduction pipe is piped from the exterior of a water storage tank through the space part between the inclined wall board parts which the hollow square pyramid which adjoins in the rainwater storage unit member of a water storage tank opposes Without using a separate piping space for the rainwater introduction pipe from the outside of the water storage tank to the filtration and precipitation tank, the rainwater introduction pipe can be easily and accurately connected to the filtration and precipitation tank using the water storage space of the rainwater storage unit. Piping can be done.

  According to the invention which concerns on Claim 6, it replaces with the rainwater storage unit member arrange | positioned around the bottom part of the manhole in the said earth-and-sedimentation tank part, and it inclines slowly downward toward the bottom face of a manhole on the upper surface of a bottom plate, Since the rainwater storage and sediment guidance unit member with the earth and sand guiding inclined surface guiding the manhole to the manhole side is arranged, the rainwater storage and soil guidance around the manhole bottom surface and the manhole bottom It can be deposited on the earth and sand guiding slope of the unit member, and the earth and sand guiding slope can be made to flow toward the bottom of the manhole and be easily guided and assembled on the bottom of the manhole. It can be performed and maintenance management becomes easy.

  According to the invention which concerns on Claim 7, it has comprised so that a filtration precipitation tank part may be provided in several places of a water storage tank, and rainwater may be introduce | transduced into these filtration precipitation tank parts from the outside through a rainwater introduction pipe | tube from the outside, respectively. Therefore, even if there is a lot of rainfall per unit time such as torrential rain, a large amount of rainwater can be diverted and introduced into each filtration and precipitation tank through multiple rainwater introduction pipes. A large amount of rainwater can be precipitated and filtered in a short time.

  According to the invention according to claim 8, a sand settling tank is provided in the ground adjacent to the water storage tank to receive rainwater from a side ditch or a drain ditch, and rainwater is introduced from the sand settling tank into the manhole through the rainwater introduction pipe. Because it is configured, after sedimentation and removal of relatively large sediments contained in rainwater flowing in through the side and drainage trenches in the settling tank, fine sediments and silts contained in rainwater are passed through the rainwater introduction pipe. It can introduce | transduce into a filtration precipitation tank part, can be captured and removed with the said water-permeable sheet, and can store the rain water which hardly contains earth and sand in a water storage tank.

A simplified longitudinal side view of a rainwater storage facility. The simplified plan view. The perspective view of a rainwater storage unit member. The longitudinal cross-sectional view of the state piled up in two steps. The perspective view of the upper half part side of the rectangular frame arrange | positioned in a manhole. The simple vertical side view of the rainwater storage facility which provided the space recessed part for earth and sand sedimentation tank part formation. The simple vertical side view of the state in which the earth and sand sedimentation tank part is formed in the space recessed part. The simple vertical side view which shows another Example of this invention rainwater storage facility. The top view of the bottom part of the earth and sand sedimentation tank part. The perspective view of a rainwater storage and earth and sand guide unit member. The longitudinal side view. The perspective view of the rainwater storage and earth-and-sand guide unit member distribute | arranged to four corner parts. The longitudinal side view. The simple vertical side view which shows another Example of this invention rainwater storage facility. The simplified plan view. The top view of the bottom part of an earth and sand sedimentation tank part. The top view which shows another structure of the bottom part of a sedimentation tank part. The simplified top view of the rainwater storage facility which has the earth and sand sedimentation tank part in several places.

  Next, a specific embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, a rainwater storage facility is a flat rectangular water storage recess formed by digging a ground such as a park to a predetermined depth. A water tank 1 is formed by laying flat and rectangular rainwater storage unit members 3 made of synthetic resin having an internal space for storing rainwater in the vertical and horizontal directions and stacking them in multiple stages. A plurality of rainwater storage unit member rows (three vertical and three rainwater storage unit member rows in the figure) arranged in parallel in the vertical and horizontal directions at a part of the lower rainwater storage unit member below the uppermost row The rainwater storage unit member laminated portion laminated up to the row is surrounded by a water permeable sheet 4 which is a filter medium, thereby providing a sedimentation tank portion 5 having a predetermined depth in a planar rectangular shape.

  Specifically, on the rainwater storage unit member row in the form of a flat quadrangle, which is arranged in parallel from the topmost rainwater storage unit member 3 in the vertical and horizontal directions on the lower side of a plurality of stages (three in the figure, 9 in total). A bottom-side water-permeable sheet 4a is laid on the bottom-side water-permeable sheet 4a, and other rainwater storage unit members 3 other than the central rainwater-storage unit member 3 in this rainwater-storage unit member row (eight in the figure). ) A rectangular cylindrical peripheral wall side water permeable sheet formed by connecting a plurality of storm water storage unit member laminated parts stacked up to the top at a right angle upward from the four sides of the bottom side water permeable sheet 4a. The sedimentation tank section 5 is formed by surrounding with 4b. The water-permeable sheet 4 is made of a nonwoven fabric or a split cloth in which a plurality of small water-permeable holes are formed by orthogonally bonding randomly arranged split yarns and thermally fusing the intersecting portions.

  The central portion of the sediment sediment tank 5 where the rainwater storage unit member 3 is not provided has a width (about 1000 mm square) corresponding to one rainwater storage unit member 3, and the bottom side water-permeable sheet 4a. A manhole 6 having a depth reaching the depth is formed, and the rainwater storage unit member laminated portion is provided around the manhole 6 in the center.

  As the rainwater storage unit member 3, for example, as shown in FIGS. 3 and 4, the lower end of the rainwater storage unit member 3 has a flat rectangular shape and has a certain thickness, and the lower end of the rainwater storage unit member 3 opens all the way downward. The hollow square pyramid 32 having a certain height is erected at a predetermined interval in the front, rear, left, and side-by-side, and the bottom plate portion 31 having a certain width is provided between the lower ends of the adjacent hollow square pyramids 32 and 32. It has a structure formed by connecting with '.

  The hollow quadrangular pyramid 32 includes a planar rectangular top plate portion 32a that is long in the front-rear direction, and inclined front and rear inclined wall plate portions that are inclined downwardly from the front, rear, left, and right edges of the top plate portion 32a. 32b, 32b ', and a V-shaped central groove portion 32c having a certain depth is provided downward from the central portion in the longitudinal direction of the top plate portion 32a, and the top plate portion 32a Further, a pair of front and rear hollow protrusions 32d and 32d are provided so as to project the opening end from the front and rear with the upper end opening of the central groove 32c as the center.

  Furthermore, the opening width dimension between the lower ends of the both side inclined wall plate portions 32b ′ and 32b ′ in the hollow quadrangular pyramid 32 is such that the top plate extends across the front and rear hollow projection portions 32d and 32d projecting from the top plate portion 32a. The lower end of the portion 32a is dimensioned so that the lower end thereof can be supported, and the rainwater storage unit members 3 and 3 can be stacked vertically while intersecting each other at right angles. Further, the bottom plate 31 in the rainwater storage unit member 3 is provided with a plurality of water passage holes 32e penetrating between the upper and lower surfaces, and also inside the front and rear hollow projections 32d and 32d. A water passage hole 32f that communicates with the water is provided.

  On the other hand, in the manhole 6, there are four columns 7a along the four corners of the manhole 6, and a rainwater storage unit in the length direction of the columns 7a with these columns in contact with the four corners. A rectangular frame member 7 (shown in FIG. 5) composed of a rectangular frame member 7b connected and supported at regular intervals equal to the thickness of the member 3 is inserted and arranged, and the four-side outer surface of the rectangular frame member 7b Are kept close to or in contact with the end surface of the bottom plate 31 of the rainwater storage unit member 3 facing each other to hold the rainwater storage unit member 3 in a stable loading state. Further, a lifting scaffold frame material 7c is attached to the inner corner of each rectangular frame material 7b.

  As shown in FIG. 1, in the rainwater storage facility in which the water storage tank 1 and the sediment sedimentation tank section 5 are provided in a part of the storage tank 1, rainwater is introduced into one end side of the rainwater in the upper end of the manhole 6. A rainwater introduction pipe 8 to be introduced is disposed, and a rainwater outlet pipe 9 for discharging rainwater in the water storage tank 1 to the outside is connected to and communicated with the lower end of the water storage tank 1 on the other end side.

  The rainwater introduction pipe 8 is configured to be opposed to the left and right adjacent hollow square frustums 32 and 32 in the uppermost rainwater storage unit member row arranged in a row from one end of the water tank 1 to the manhole 6. The pipe is routed through a straight groove-shaped water storage space provided between the wall plate portions 32b ′ and 32b ′, and the front end opening faces the upper end opening of the manhole 6. The base end of the rainwater introduction pipe 8 drawn out from one end side of the water storage tank 1 may be directly communicated with the side groove or drainage groove side, but in the figure, one end side of the water storage tank 1 is shown. A sand settling tank 10 for receiving rainwater from a side ditch or a drain ditch is provided in the outer ground of the pipe, and the base end of the rainwater introduction pipe 8 is communicated with the sand settling tank 10. The number of rainwater introduction pipes 8 from the sand settling tank 10 to the manhole 6 is not limited to one, and a plurality of pipes may be provided.

  On the other hand, the rainwater lead-out pipe 9 is communicated with the lower end portion of the drainage tank 11 built in the outer ground on the other end side of the water storage tank 1. The drain tank 11 is provided with a spillway 12 having an orifice 12a for adjusting the flow rate at the lower end.

  In order to construct the rainwater storage facility constructed as described above, first, after excavating the ground of a park or the like to provide the water storage recess 2, protection is provided from the bottom surface of the water storage recess 2 to the entire surface of the excavation wall in all directions. The water storage tank 1 is formed by laying and covering the sheet 13 and the water-impervious sheet 14 in an overlapping state, and then arranging and loading the rainwater storage unit members 3 in multiple rows and multiple rows.

  In order to form this water tank 1, first, the lengthwise direction of the hollow square frustums 32 of all the rainwater storage unit members 3 is set in the same direction on the water shielding sheet 14 laid on the bottom surface of the water storage recess 2. After forming the first-stage (bottom-stage) rainwater storage unit member row so as to be in a state of being oriented, a large number of second-stage stormwater storage unit members 3 are formed on all the first-stage rainwater storage unit members 3. The rain water storage unit members 3 are overlapped so that the hollow square frustum 32 is perpendicular to the hollow square frustum 32 of the lower rainwater storage unit member 3, and the lower end opening of the hollow square frustum 32 is formed. The bottom rainwater storage unit member 3 facing the lower end opening is supported on both ends of the top plate portion 32a of the hollow square frustum 32.

  Similarly, the water tank 1 is formed by loading the rain water storage unit member 3 on the upper stage side in a plurality of stages sequentially while changing the direction so as to be orthogonal to the rain water storage unit member 3 on the lower stage side. In the course of forming the water tank 1, several stages (three stages in the figure) of the rainwater storage unit member row are formed on the lower side, and then the rainwater storage unit on the upper side is formed upward from the rainwater storage unit member row of the several stages. The unit member rows are arranged and stacked in several stages (five stages in the figure). At this time, as shown in FIG. 6, a space recess 15 in which a part of the upper-stage rainwater storage unit member row is not stacked is provided at the center of the water storage recess 2. The width of the space recess 15 has a width corresponding to several rainwater storage unit members 3, in the figure, three vertically and horizontally, a total of nine rainwater storage unit members 3 in parallel.

  After the formation of the space recess 15, the bottom surface of the space recess 15, that is, the rainwater exposed in the space recess 15 in the uppermost rainwater storage unit member row of the lower-stage rainwater storage unit member row stacked. A bottom-side water-permeable sheet 4a is laid on the top surface of the storage unit member 3 and is connected to the bottom-side water-permeable sheet 4a so as to rise from the four sides of the bottom-side water-permeable sheet 4a on the four circumferential surfaces of the space recess 15. The peripheral wall side water permeable sheet 4b is stretched, and the peripheral wall side water permeable sheet 4b covers the entire laminated surface of the upper-stage rainwater storage unit member rows exposed on the four surfaces of the space recess 15 respectively. The upper end portion of the peripheral wall side water permeable sheet 4b is folded over the uppermost rainwater storage unit member row.

  Thus, after laying and stretching the water permeable sheet 4 from the bottom surface of the space recess 15 to the four circumferential surfaces, a plurality of steps (five steps in the figure) are provided on the water permeable sheet 4a laid on the bottom surface of the space recess 15. The lowermost upper-stage rainwater storage unit member row in the upper-stage rainwater storage unit member row is disposed. At this time, the rainwater storage unit members 3 are not provided in the central portion of the space recess 15, but a plurality of rainwater storage unit members 3 are arranged vertically and horizontally so as to surround the central portion. That is, in the drawing, a space corresponding to one rainwater storage unit member 3 is provided in the center of the space recess 15 so that three rainwater storage unit members 3 are arranged vertically and horizontally around the space. It is installed side by side.

  Further, after providing the lowermost rain water storage unit member row at the bottom of the upper rain water storage unit member row on the bottom surface of the space recess 15 in this manner, a single rainwater is placed in the center of the space recess 15 in the same manner. The next upper-stage rainwater storage unit member row is stacked so as to provide a space corresponding to the storage unit member 3, and this loading operation is repeated to provide the rainwater storage unit member 3 at the center in the space recess 15. A rainwater storage unit member stacking portion composed of a plurality of upper-stage rainwater storage unit member rows having manholes 6 formed by unspaced spaces is formed and extends from the bottom surface of the rainwater storage unit member stacking portion to the four circumferential surfaces. Then, a sedimentation tank section 5 formed by covering with the water permeable sheet 4 is formed. In this rainwater storage unit member laminated portion, the upper rainwater storage unit member 3 is stacked so as to be orthogonal to the lower rainwater storage unit member 3.

  Thereafter, the rectangular frame 7 is inserted and installed in the manhole 6, and a large number of vertically penetrating through the entire upper surface of the uppermost rainwater storage unit member row in the water tank 1 as shown in FIG. A partition plate 16 made of a rigid material having water passage holes 17 is laid vertically and horizontally to form a reinforcing layer, and a water permeable sheet or a water shielding sheet is laid on the reinforcing layer and covered with a covering layer made of earth and sand. Form a pavement layer. A lid 18 is provided at the upper end inspection port of the manhole 6 so as to be openable and closable.

  The rainwater storage facility constructed in this way sends the rainwater that has flowed into the gutter and drainage ditch during the rain into the sand settling tank 10 and temporarily retains it in the sand settling tank 10 for comparison with soil and sand contained in the rainwater. Sediment or the like having a large target particle size is settled and deposited on the bottom of the sand settling tank 10. The accumulated earth and sand will be sucked and removed at a later date using a suction hose from the ground side. On the other hand, the rainwater flowing into the manhole 6 provided in the central part of the sediment sediment tank 5 in the water storage tank 1 through the rain water introduction pipe 8 from the sand sediment tank 10 is laid on the bottom side of the sediment sediment tank 5. The permeable sheet 4a captures the earth and sand contained in this rainwater, passes through the bottom side permeable sheet 4a while being filtered and is stored in the storage space of the rainwater stormwater storage unit member row on the lower side, and the water level rises. Accordingly, when flowing from the rainwater storage unit member laminated portion surrounded by the peripheral wall side permeable sheet 4b to the rainwater storage unit member row side on the upper stage around this rainwater storage unit member laminated portion, it is included in rainwater. While the earth and sand being trapped and filtered by the peripheral wall side permeable sheet 4b, the soil and sand are transmitted through the peripheral wall side permeable sheet 4b and stored in the water storage space portion of the rainwater storage unit member row on the upper stage side.

  Furthermore, the earth and sand contained in the rainwater staying in the earth and sand settling tank portion 5 settles and the bottom plate portion 31 ′ of each rainwater storage unit member 3 in the rainwater storage unit member row around the manhole in the earth and sand settling tank portion 5 and While depositing on the bottom side permeable sheet 4a, rainwater from which sediment has been removed is stored in the water storage tank 1 outside the sedimentation tank section 5.

  The rainwater from which the earth and sand have been removed in this way flows out into the drainage tank 11 through the rainwater lead-out pipe 9 provided at the lower end of the other end of the water storage tank 1, and the river etc. through the drainage pipe 19 while the flow rate is adjusted by the orifice 12a. To be discharged. Further, when the water tank 1 becomes full, it overflows from the spillway 12 provided in the drain tank 11 and is discharged to a river or the like through the drain pipe 19. Moreover, a pump can be installed in the drainage tank 11, and the rainwater in the drainage tank 11 can be pumped up and used for watering a park or the ground.

  As rainwater in the water storage tank 1 is drained to the drainage tank 11 side and the water level drops, a part of the earth and sand captured by the peripheral wall side permeable sheet 4b is caused by the flow of rainwater, vibration transmitted from the ground side, etc. It separates from the peripheral-wall-side permeable sheet 4b, falls, and accumulates on the bottom plate 31 'of each storm-water storage unit member 3 and the bottom-side permeable sheet 4a in the storm-water storage unit member row in the sediment sediment tank 5.

  In order to remove the accumulated sediment, etc., the rainwater in the water tank 1 is drained to the extent that the work can be performed, and then the sediment deposited on the bottom-side permeable sheet 4a laid on the bottom surface of the manhole 6 is removed. Each of the rainwater storage unit members in the rainwater storage unit member row in the sediment and the sedimentation tank 5 is inserted and sucked into the manhole 6 from the ground side for suction and removal. 3 is ejected from the manhole 6 through the space between the adjacent hollow square frustums 32, 32 in the rainwater storage unit member row of each stage from the manhole 6 (not shown). And the earth and sand trapped on the peripheral wall side water permeable sheet 4b is washed off by the jet water (high pressure water) sprayed from the tip thereof and the washed earth and sand is deposited on the bottom plate portion 31 'of the rainwater storage unit member 3 And it has a bottom plate portion 31 'above with sediment discharged on the bottom of the manhole 6 by the flow of jet water flowing toward the manhole 6 side, to eliminate the outside by suction or the like.

  Moreover, when the water-permeable sheet 4 is damaged or when the filtration capacity is reduced and replaced, the rectangular frame 7 and the rainwater storage unit member laminated portion in the sediment sediment tank 5 are removed from the ground side, and the water-permeable sheet 4 is removed. And the rectangular frame body 7 and the rainwater storage unit member laminated portion may be provided in the earth and sand reservoir 5 again.

  FIG. 8 shows another embodiment of the rainwater storage facility according to the present invention. In the above embodiment, the rainwater storage unit member laminated portion loaded in the sediment sedimentation tank section 5 is entirely stored in the same structure. Although formed by the unit member 3, in this embodiment, the rainwater storage unit member row at the bottom of the rainwater storage unit member laminated portion, that is, the rainwater storage unit member row disposed around the bottom of the manhole 6 is provided. Several (8 in the figure) rainwater storage unit members to be formed are formed by two types of rainwater storage and sediment guidance unit members 3A and 3B having a different structure from the other rainwater storage unit members 3.

  Of these rainwater storage / sediment guidance unit members 3A, 3B, one rainwater storage / sediment guidance unit member 3A has a planar shape with the bottom plate 31 of the rainwater storage unit member 3 as shown in FIGS. Sediment guidance in which the upper surface of the same-sized and same-shaped bottom plate 31a is gently inclined obliquely downward from the outer edge toward the peripheral wall side water-permeable sheet 4b toward the inner edge toward the bottom of the manhole 6 A hollow surface is formed on the inclined surface 31a 'and has a flat top surface for supporting the rainwater storage unit member 3 placed on the rainwater storage / sediment guidance unit member 3A on the top surface of the soil guidance surface 31a'. The pyramidal protrusions 32a are provided in the vertical and horizontal directions at regular intervals.

The height from the bottom plate bottom surface of the rainwater storage / sediment guidance unit member 3A to the top surface of the hollow pyramid protrusion 32a is equal to the height from the bottom plate bottom surface of the rainwater storage unit member 3 to the top surface of the hollow quadrangular pyramid 32. doing. Further, all the hollow pyramidal protrusions 32a have their lower ends fully opened downward from the bottom surface of the bottom plate 31a and have water-permeable holes 33a formed on the top surface thereof.

There is no water permeable hole, so that the earth and sand on the bottom plate can be guided to the manhole 6 side through the earth and sand guiding inclined surface 31a 'without sinking the earth and sand downward from the bottom plate 31a. .

  The hollow pyramidal protrusion 32a may protrude directly from the bottom plate 31a, but in the figure, the lower end is entirely on the outer edge and both side edges of the bottom plate 31a downward from the lower surface of the bottom plate 31a. A hollow pyramid wall 34a that is open on the hollow rib wall 34a is provided with a hollow pyramidal protrusion 32a on the hollow rib wall 34a, and also between the hollow rib walls 34a and 34a on both side edges. In addition, hollow ridge walls 34a 'for dividing the earth and sand guiding inclined surface 31a' into several parts are juxtaposed, and hollow pyramid protrusions 32a are protruded from these hollow ridge walls 34a '.

  Further, as shown in FIG. 9, the other rainwater storage / sediment guidance unit member 3B is disposed at the corner of the rainwater storage / sediment guidance unit member row, and the bottom plate 31 of the rainwater storage unit member 3 As shown in FIGS. 12 and 13, the upper surface of the bottom plate 31b having the same planar shape and the same shape is directed toward the outer corners of the peripheral wall side water-permeable sheet 4b and the corners of the manhole 6 as shown in FIGS. It is formed on the earth and sand guiding inclined surface 31b ′ that is inclined gently and obliquely downward from the center toward the adjacent rainwater storage and sediment guiding unit members 3A and 3A. At the same time, the lower inclined end of the earth and sand guiding inclined surface 31a ′ is configured to communicate with the earth and sand guiding inclined surface 31a ′ of the adjacent rainwater storage and earth and sand guiding unit members 3A and 3A.

  Further, a hollow pyramid protrusion 32b having a flat top surface for supporting the rainwater storage unit member 3 placed on the rainwater storage and sediment guidance unit member 3B is provided on the upper surface of the earth and sand guiding inclined surface 31b '. The hollow earth pyramid protrusions 32a projecting from the earth and sand guiding unit member 3A are projected at the same height and at the same intervals.

  These hollow pyramidal protrusions 32b may be provided directly from the bottom plate 31b in the same manner as the one rainwater storage / sediment guidance unit member 3A, but the rainwater storage / sediment guidance unit member 3B A hollow ridge wall projecting on the earth and sand guiding inclined surface 31b 'so as to divide the earth and sand guiding inclined surface 31b' between the diagonal line and the edge adjacent to the rainwater storage and earth and sand guiding unit member 3B at right angles. It protrudes from the upper surface of 34b.

  In addition, all the hollow pyramidal protrusions 32b have their lower ends opened entirely from the lower surface of the bottom plate 31b through the lower end openings of the hollow ridge walls 34b, and water-permeable holes 33b are formed on the top surfaces thereof. However, the bottom plate 31b is not provided with a water-permeable hole, and therefore, the sediment on the bottom plate is allowed to pass along the sediment-induced slope 31b ′ without sinking the sediment downward from the bottom plate 31b. The storage and sediment guiding unit members 3A and 3A are configured to flow on the sediment and sand guiding inclined surface 31a ′.

  The two types of rainwater storage / sediment guidance unit members 3A and 3B configured as described above are configured such that one rainwater storage / sediment guidance unit member 3A is inclined downward on the four sides of the bottom of the manhole 6 with respect to the sediment guidance inclined surface 31a ′. The other rainwater storage / sediment guidance unit member 3B is disposed at the corner between the rainwater storage / sediment guidance unit members 3A and 3A adjacent to each other at right angles so that the ends are joined to each other. Sediment-induced slopes 31b 'and 31b' on both sides that are connected at right angles with the diagonal line at the center communicate with the sediment-induced slope 31a 'of the adjacent rainwater storage and sediment guidance unit members 3A and 3A. It is disposed on the bottom-side water-permeable sheet 4A so as to make it. Since other configurations are the same as those in the above embodiment, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the rainwater storage unit member stacking portion loaded in the sedimentation tank section 5 surrounded by the permeable sheet 4, the rainwater storage unit member row at the lowermost stage is the above two types of rainwater storage / sediment guidance unit members 3A, 3B. The sediment sedimentation in the sediment sedimentation tank section 5 is caused to cause sedimentation of one rainwater storage / sediment guidance unit member 3A in the rainwater storage / sediment guidance unit member row around the bottom of the manhole 6 and around the bottom of the manhole. It is deposited on the slope 31a 'and on the sediment-induced slope 31b' of the other rainwater storage / sediment guidance unit member 3B, and from the rainwater storage / sediment guidance unit 3A, the soil is passed through the soil-seduce slope 31a '. It can be smoothly guided to and accumulated on the bottom surface of the manhole 6 and is adjacent to the other earth and sand guiding inclined surface 31b 'from the other rainwater storage and sediment guiding unit member 3B. Are guided on the earth and sand guiding inclined surfaces 31a 'and 31a' of the rainwater storage and earth guiding unit members 3A and 3A, and guided and accumulated in the manhole 6 through these earth and sand guiding inclined surfaces 31a 'and 31a'. Can do.

  14 to 16 show still another embodiment of the present invention. In the above embodiment, the rainwater storage unit member 3 is placed in a flat rectangular water storage recess 2 formed by digging the ground to a predetermined depth. In the water tank 1 formed by laying out the vertical and horizontal and loading them in multiple stages, the sediment sedimentation tank section 5 formed in a part of the water tank 1 is divided into three vertical and horizontal, totaling nine pieces. It has a width corresponding to the parallel configuration of the rainwater storage unit members 3 and a depth corresponding to the height of a plurality of levels (five levels in the figure) from the rainwater storage unit member row at the top. A space recess 15 is provided, and permeable sheets 4a, 4b are stretched from the upper surface of the rainwater storage unit member 3 on the lower side, which is exposed at the lower end opening of the space recess 15 and forms the bottom surface of the space recess 15, to the four circumferential surfaces At the center of the space recess 15 Eight rainwater storage unit members 3 arranged in a row vertically and horizontally around the space portion so that a space portion having an area corresponding to the area of the rainwater storage unit member 3 is provided over the entire height of the space recess 15. A plurality of storm water storage unit member rows (5 in the figure) are stacked to form a sedimentation tank portion 5 having a manhole 6 in the center, but in this embodiment, a manhole 6 ' Is provided so as to be along the one side wall surface of the water storage recess 2 without being provided at the center of the sediment sediment tank 5 '.

  Specifically, rainwater storage unit members 3 having the same structure and the same shape as the above embodiment are laid vertically and horizontally in a flat rectangular water storage recess 2 formed by digging the ground to a predetermined depth and loaded in multiple stages. In the water storage tank 1 formed by doing, 3 of the rainwater storage unit member 3 arranged in the vertical direction (length direction of the water storage tank 1) along this one side wall surface on the one side wall surface side of the water storage tank 1. It has a flat rectangular area with a length corresponding to two and a width corresponding to two rainwater storage unit members 3 arranged in the lateral direction (width direction of the water tank 1), and the depth. Is provided with a space recess 15 ′ having a depth corresponding to the height of a plurality of steps (five steps in the figure) from the uppermost rainwater storage unit member row, and is exposed at the lower end opening of the space recess 15 ′. Rain water on the lower side forming the bottom surface of the space recess 15 ' A bottom side permeable sheet 4a 'is laid on the top surface of a plurality (six in the figure) of the rainwater storage unit members 3 in the distillation unit member row, and from the bottom surface of the space recess 15' to a portion other than the one side wall surface side of the water storage tank 1 The circumferential wall side water permeable sheet 4b 'is stretched over the three sides of the space recess 15', and the circumferential wall side water permeable sheet 4b 'is loaded on the three sides of the space recess 15' so as to surround the space recess 15 '. The laminated surface exposed to the space recess 15 ′ in the upper rainwater storage unit member row is entirely covered.

  Furthermore, five rainwater storage unit members 3 are placed in the above-described planar rectangular space recess 15 ′ having such a size that six rainwater storage unit members 3 can be arranged vertically and horizontally so as to be in two rows. A manhole 6 'corresponding to the width of one rainwater storage unit member 3 is formed in a portion facing the one side wall surface side of the water storage tank 1 by stacking vertically and horizontally and stacking a plurality of stages (five stages). Yes.

  Specifically, two rainwater storage unit members 3 are arranged along one side wall surface of the water storage tank 1 on the bottom side water-permeable sheet 4a ′ laid on the bottom surface of the space recess 15 ′. Are arranged in the vertical direction (the length direction of the water storage tank 1) with an interval corresponding to the length of the rainwater storage unit member 3 between the rainwater storage unit members 3, 3 A corresponding space is provided, and the rainwater storage unit members 3 and 3 are arranged in the lateral direction so as to abut against the inside of these rainwater storage unit members 3 and 3, that is, the surface opposite to the one side wall surface of the water tank 1. Further, by arranging one rainwater storage unit member 3 between the facing surfaces of these rainwater storage unit members 3 arranged side by side, 5 pieces surrounding the three sides of the space portion. Plane U-shaped rainwater storage unit consisting of the rainwater storage unit member 3 A knit member row is formed.

  The rainwater storage unit member row is stacked in a plurality of stages (five stages) in the space recess 15 ′, and one rainwater storage unit is provided at a portion facing the one side wall surface of the water tank 1 water tank 1. A manhole 6 'corresponding to the width of the member 3 is formed, and the water permeable sheet extends from the bottom surface of the rainwater storage unit member laminated portion to the three circumferential surfaces other than the surface in contact with the one side wall surface of the water tank 1. A sedimentation tank portion 5 'formed by covering with 4' is formed. In the rainwater storage unit member stacking portion in the space recess 15 ′, the lower rainwater storage unit member 3 is similar to the rainwater storage unit member 3 loaded in the water storage tank 1 outside the space recess 15 ′. The upper rainwater storage unit members 3 are stacked so as to be orthogonal to each other.

  The rectangular frame 7 is inserted and installed in the manhole 6 ′ of the sediment sedimentation tank section 5 ′ thus configured, and the entire upper surface of the uppermost rainwater storage unit member row in the water tank 1 is installed. Further, as shown in FIG. 14, a reinforcing layer is formed by laying a partition plate 16 made of a rigid material having a large number of water passage holes penetrating vertically in the vertical and horizontal directions, and a water permeable sheet or a water shielding layer is formed on the reinforcing layer. A pavement layer is formed by laying a sheet and covering with a covering layer made of earth and sand, a point that a lid 18 can be opened and closed at the upper end inspection port of the manhole 6 ′, and further from the sand settling layer 10. Since the rainwater is introduced into the manhole 6 ′ provided in the sedimentation tank section 5 ′ through the rainwater introduction pipe 8 and the other structures are the same as in the above embodiment, the same parts are denoted by the same reference numerals and detailed. The detailed explanation is omitted.

  In the rainwater storage facility configured as described above, rainwater is supplied to the manhole 6 ′ provided in the sedimentation tank 5 ′ in the water storage tank 1 from the sand settling tank 10 through the rainwater introduction pipe 8 in the same manner as in the above embodiment. Let it flow. Further, the rainwater flowing into the manhole 6 ′ is captured and filtered by the bottom side permeable sheet 4a ′ laid at the bottom of the sediment settling tank section 5 ′, and the rainwater rainwater on the lower stage side is captured and filtered. Peripheral wall side water permeability from the rainwater storage unit member stacking part in the sediment sediment tank 5 'which is stored in the water storage space part of the storage unit member row and surrounded by the peripheral wall side water permeable sheet 4b' as the water level rises The sheet 4b passes through and is stored in the water storage space of the rainwater storage unit member row on the upper side.

  The earth and sand contained in the rainwater staying in the sediment sedimentation tank section 5 ′ settles down, and the bottom plate portion 31 ′ of each rainwater storage unit member 3 in the rainwater storage unit member row around the manhole in the sediment sedimentation tank section 5 ′. The rainwater that has accumulated on the bottom side permeable sheet 4a 'and circulated outside the sedimentation tank section 5 flows out into the drain tank 11 through the rainwater outlet pipe 9 provided at the lower end of the other end of the water tank 1, It is discharged to the river etc. through the drain pipe 19. The method for removing the sediment deposited on the bottom of the sediment sediment tank 5 'is the same as in the above embodiment.

  Further, in the rainwater storage unit member stacking portion loaded in the sedimentation tank section 5 ′, the rainwater storage unit member row provided at the lowest stage, that is, arranged around the three sides at the bottom of the manhole 6 ′. Two rainwater storage unit members forming the rainwater storage unit member row (five in the figure) have two types of rainwater having the structure shown in FIGS. 10 to 13 in the same manner as the rainwater storage facility shown in FIG. It may be formed by combining the storage unit members 3A and 3B.

  FIG. 17 shows the embodiment. One of the two types of rainwater storage / sediment guidance unit members 3A, 3B is connected to one rainwater storage / sediment guidance unit member 3A in the length direction of the water tank 1 at the bottom of the manhole 6 ′. Is arranged on the bottom side permeable sheet 4A so that the bottom inclined end of the earth and sand guiding inclined surface 31a 'is joined to the three edges of the edge facing the surface and the inner edge facing the width direction of the manhole 6'. Sediment on both sides where the other rainwater storage / sediment guidance unit member 3B is connected to the corner between the rainwater storage / sediment guidance unit members 3A, 3A adjacent to each other at a right angle, with the diagonal line at the center. The lower inclined ends of the guiding inclined surfaces 31b ′ and 31b ′ are arranged on the bottom-side water-permeable sheet 4A so as to communicate with the earth and sand guiding inclined surfaces 31a ′ of the adjacent rainwater storage and sediment guiding unit members 3A and 3A. Since other configurations are the same as those of the embodiment shown in FIGS. 14 to 16, the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

  In the rainwater storage unit member stacking portion loaded in the sediment sedimentation tank section 5 ′ surrounded by the water permeable sheet 4 ′ in this way, the rainwater storage unit member row at the bottom is used as the above two types of rainwater storage and sediment guidance. If formed by the unit members 3A and 3B, the sediment settled in the sediment sedimentation tank section 5 'is one rainwater storage and sediment in the rainwater storage and sediment guidance unit member row around the bottom of the manhole 6' and the bottom of the manhole. It is deposited on the earth and sand guiding inclined surface 31a 'of the guiding unit member 3A and on the earth and sand guiding inclined surface 31b' of the other rainwater storage and sediment guiding unit member 3B, and from the one rainwater storing and sand guiding unit member 3A Sediment can be smoothly guided and accumulated on the bottom surface of the manhole 6 through the inclined surface 31a ', and from the other rainwater storage and sediment guiding unit member 3B, it is adjacent to the sediment-induced inclined surface 31b'. Is guided on the earth and sand guiding inclined surfaces 31a 'and 31a' of one rainwater storage and earth guiding unit member 3A and 3A, and is guided and accumulated in the manhole 6 through these earth and sand guiding inclined surfaces 31a 'and 31a'. Can do.

  In any of the above-described embodiments, the sedimentation tank sections 5 and 5 ′ are provided only at one location in the water storage tank 1, but for example, a manhole 6 ′ is provided in the center of the sedimentation tank section 5. 18 are provided in several places as shown in FIG. 18, and the rainwater in the uppermost stage of the water storage tank 1 from the sand settling tank 10 to the upper end opening of the manhole 6 of these earth and sand settling tank sections 5, 5, 5 The rainwater introduction pipes 8, 8, 8 may be respectively piped through the space between the inclined wall plate parts 32 b ′, 32 b ′ of the adjacent hollow square frustums 32, 32 in the storage unit member row. The same applies to the sedimentation tank section 5 ′ provided with the manhole 6 ′ along one side wall surface of the water storage tank 1.

DESCRIPTION OF SYMBOLS 1 Water storage tank 2 Water storage recessed part 3 Rainwater storage unit member
3A, 3B Rainwater storage and sediment guidance unit 4 permeable sheet 5 sediment sediment tank 6 manhole 7 rectangular frame 8 rainwater introduction pipe 9 rainwater lead-out pipe
10 Sand settling tank
11 Drainage tank

Claims (8)

A water storage tank is formed by laying a rainwater storage unit member having an internal space for storing rainwater vertically and horizontally in a water storage recess formed by excavating the ground and stacking it in multiple stages, and the upper surface of this water tank is covered with a covering material In the rainwater storage facility that is covered, a part of the water storage tank has a depth that reaches the lower-stage rainwater storage unit member row below the plurality of stages from the uppermost rainwater storage unit member, and the lower-side rainwater Provided with a sediment sedimentation tank part that covers the upper part of the plurality of upper rainwater storage unit members stacked from the top surface of the storage unit member row with a water permeable sheet and forms a manhole in the sedimentation tank part In addition, a rainwater introduction pipe for introducing rainwater into the manhole from the outside of the water storage tank is disposed, and rainwater is discharged to the outside from the lower end of the water storage tank. Rainwater storage facility characterized in that it rainwater discharge pipe that is provided. One rainwater storage unit is removed by removing a part of the rainwater storage unit member of the rainwater storage unit member laminated portion covered with the water permeable sheet up to the lower rainwater storage unit member in which the water permeable sheet is laid on the upper surface. A manhole having a width in a plane direction corresponding to the area of the member is formed, and the rainwater storage unit member stacking portion in which a row of rainwater storage unit members are vertically and horizontally stacked around the manhole is provided. The rainwater storage facility according to claim 1, wherein:   Four struts along the four corners of the manhole in the manhole, and a rectangular frame member attached at regular intervals in the length direction of the strut with the four corners in contact with these pillars A rainwater storage facility according to claim 1 or 2, wherein a rectangular frame body made of is inserted and disposed, and a lifting frame material is attached to the rectangular frame body.   The rainwater storage unit member has a rectangular quadrangular bottom plate, and a hollow square pyramid with a fixed height with its lower end penetrating through the bottom plate and opening downward. When the upper and lower rainwater storage unit members are stacked in the vertical direction, the lower end of both side inclined wall plates of the hollow square pyramid in the upper rainwater storage unit member is the hollow four of the lower rainwater storage unit member corresponding to the hollow square pyramid. The rainwater storage facility according to claim 1, wherein the rainwater storage facility is configured to be supported by upper surfaces of both end portions in the length direction of the top plate portion of the truncated pyramid. The rainwater introduction pipe is provided between the inclined wall plate portions facing the hollow square pyramid adjacent to the left and right in the uppermost rainwater storage unit member row arranged in a row from one end side of the water tank to the manhole . The rainwater storage facility according to claim 1 or 4, wherein the rainwater storage facility is piped through a straight groove-shaped water storage space .   Instead of the rainwater storage unit member arranged around the bottom of the manhole in the sediment sedimentation tank section, a sediment-inducing slope that gently slopes downward on the top of the bottom plate toward the bottom of the manhole and guides the sediment to the manhole side. The rainwater storage facility according to claim 1 or 2, wherein a rainwater storage / sediment guidance unit member is provided.   Claims 1 and 2 are characterized in that a filtration / sedimentation tank part is provided at several locations of the water storage tank, and rainwater is introduced from the outside of the water storage tank to the filtration / sedimentation tank part from outside through a rainwater introduction pipe. Item 6. A rainwater storage facility according to item 2 or claim 5.   A sand settling tank is provided in the ground adjacent to the water storage tank to receive rainwater from a side ditch or a drainage ditch, and rainwater is introduced from the sand settling tank into a manhole through a rainwater introduction pipe. The rainwater storage facility according to claim 1 or claim 5.

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