JP5117793B2 - Underground water tank - Google Patents

Description

  The present invention relates to an underground water tank provided in the basement of a parking lot, a park, a site, and the like.

  In urbanized areas where there are few unpaved roads and vacant lots, rainwater that has fallen on houses, parking lots, roads, etc. flows into the river through the side ditches of the road without penetrating into the ground, so in the rainy season A large amount of rainwater concentrates on the river, and there is a risk of causing so-called urban flooding in a short time, exceeding the capacity of the river. On the other hand, during the dry season, the water level of dams and lakes drops and water shortages occur, so water supply restrictions are implemented in various places, making it difficult to provide a sufficient amount of water to garden plants.

  Under such circumstances, a rainwater storage tank is installed in the basement, and after temporarily storing rainwater, it is gradually discharged into rivers, etc. to prevent urban flooding or to pump rainwater stored in the rainwater storage tank. Effectively used for car washing and watering plants.

  As this rainwater storage tank, a recessed space for a tank with an open top is formed in the ground, and the rainwater storage tank is covered with a non-permeable sheet such as a rubber sheet from the bottom of the recessed space for the tank to the middle of the circumferential side. There is known a rainwater storage and infiltration tank which is made into a rainwater infiltration tank by covering the upper part of the rainwater storage tank with a water permeable sheet (Patent Document 1).

The rainwater storage and infiltration tank is designed to gradually infiltrate rainwater into the ground from the rainwater infiltration tank when the rainwater storage tank is full. Since the water does not penetrate into the ground, drainage efficiency is poor, and rainwater may overflow when the amount of inflow exceeds the amount of rainwater infiltrated, as in heavy rain. As a countermeasure, if the surface area of the rainwater infiltration tank is increased, there is a problem that the amount of water stored in the rainwater storage tank is reduced.
JP-A-9-41470

  The present invention has been made in view of the above problems, and the problem to be solved is that drainage efficiency is good when overflowing without reducing the amount of water stored in the reservoir, and there is no fear of overflowing rainwater. To provide a groundwater tank.

In order to achieve the above object, a groundwater tank according to the present invention forms a storage part for storing rainwater in the ground, and provides an overflow part at the upper part of the side or / and the top part of the storage part . the top surface and side surfaces and a bottom surface, and additionally provided with water flow-permeable sheet having a water passing portion and permeability surface, water flow-permeable sheet of the top surface is by folding the additionally provided been passing water-permeable sheet on the side surface It is characterized by being attached .

In the underground water tank of the present invention, the water flow / water permeable sheet has a water permeable surface as a sheet surface on which a plurality of water permeable holes are formed, and a continuous space between a plurality of convex portions provided on both surfaces or one surface. It is preferable that the tip of the convex portion is attached so as to be located on the storage portion side. Moreover, it is preferable to coat both surfaces or one surface of the water-permeable / permeable sheet with a water-permeable coating material, and the water-permeable coating material is more preferably a nonwoven fabric or a woven fabric. In particular, the height of the convex part of the water-permeable / permeable sheet is 5 mm to 50 mm, the area of the convex part tip in contact with the storage part side is 10 mm ^{2 to} 250 mm ² , and the pitch between the convex parts is 10 mm to 110 mm A water tank is preferred.

  On the other hand, the water-permeable / permeable sheet is a thick non-woven fabric or woven fabric, and a base having a large number of rod-shaped projections or a panel having a large number of rod-shaped projections and water-permeable portions on the outside thereof. A water tank is also preferred. In addition, a water-impervious sheet except for a groundwater tank in which the storage part is a water tank formed of concrete, metal, or synthetic resin, or an upper side part and / or a top surface part of a space in which the storage part is formed in the ground. The portion not covered with the water-impervious sheet is used as an overflow portion, and a filling material for a groundwater tank comprising a rectangular beam body and a plurality of support legs for supporting the beam body therein is provided. A filled underground water tank is preferred.

Underground water tank of the present invention, the flow path of rainwater is formed by water passing portion of the water flow-permeable sheet is additionally provided on the top surface and the side and bottom surfaces of the reservoir. Therefore, rain water overflowing from the overflow portion of the reservoir is spreads uniformly over the top surface and the side surface and the bottom surface of the reservoir flows through the water passing portion of the water flow-permeable sheet, ground from permeable surface of the water passing-permeable sheet Will penetrate. In this way, the surface integral of the storage part acts as a permeation part, so that the permeation efficiency is very high and there is no fear of rainwater overflowing from the underground water tank. And since the overflow part is provided in the upper part or top | upper surface of the storage part, the ratio of the storage volume of the storage part with respect to a groundwater tank is very large, and there is no worry that the amount of water storage of a storage part decreases.

  The water flow / water permeable sheet has a sheet surface in which a plurality of water permeable holes are formed as a water permeable surface and a continuous space between a plurality of convex portions provided on both sides or one side. Like the underground water tank attached so that the tip of the part is located on the side of the storage part, if the water-permeable / permeable sheet is configured as described above, the water-permeable part is reliably formed by a large number of convex parts. Therefore, the overflowed rainwater will spread evenly to the side and bottom of the reservoir, or the top and side and bottom, and will penetrate into the ground through the water-permeable holes. Go.

  In addition, a groundwater tank in which both sides or one side of a water-permeable / permeable sheet is covered with a water-permeable covering material prevents clogging of the water-permeable holes of the water-permeable / permeable sheet and ensures good water permeability. be able to.

  Furthermore, the groundwater tank in which the water-permeable covering material is a nonwoven fabric or a woven fabric exhibits high filter performance because the nonwoven fabric or the woven fabric is less likely to be clogged, and can quickly introduce rainwater into the ground. Moreover, since it is excellent also in corrosion resistance, it can also maintain high performance over a long period of time.

In particular, the height of the convex part of the water-permeable / permeable sheet is 5 mm to 50 mm, the area of the convex part tip in contact with the storage part side is 10 mm ^{2 to} 250 mm ² , and the pitch between the convex parts is 10 mm to 110 mm as aquarium, the dimensions of the projections, the pitch is as described above, can be obtained sufficiently withstand 0.5tf ^/ m ² ~5tf / m 2 about earth pressure envisaged underground tank.

  On the other hand, the water-permeable / permeable sheet is a thick non-woven fabric or woven fabric, and a base having a large number of rod-shaped projections or a panel having a large number of rod-shaped projections and water-permeable portions on the outside thereof. The water tank serves as a water / permeable sheet in which a thick nonwoven fabric or woven fabric has a water-permeable portion and a water-permeable surface. At this time, the thickness of the nonwoven fabric or woven fabric is reduced by earth pressure only by attaching the nonwoven fabric or woven fabric to the periphery of the storage part, and the water permeability deteriorates accordingly, but the groundwater tank of the present invention has many Since the non-woven fabric or woven fabric is covered from the outside with a net body having rod-shaped projections or a panel body having a large number of rod-shaped projections and water-permeable portions, the rod-shaped projections serve as a retentive stick and the thickness of the non-woven fabric or woven fabric. There is no worry that water permeability will deteriorate.

  And the underground water tank whose storage part is a water tank made of either concrete, metal, or synthetic resin is just digging the ground and filling the water tank of concrete, metal, or synthetic resin into the dug space Since the storage part can be formed, the construction is easy and the pressure resistance and durability are excellent. Moreover, when the tank is backfilled in the ground, a water-permeable / permeable sheet is attached so that the earth pressure acts on the tank uniformly, and there is no load on the specific location, so the tank is broken. Can also be prevented. In addition, even if there is a hard object such as stone during backfilling, it is guarded by a water-permeable / permeable sheet and does not directly hit the aquarium, so there is no worry of damaging the aquarium.

  Further, the storage part is covered with a water shielding sheet except for the upper part of the side surface or / and the top surface part of the space formed in the ground, and the part not covered with the water shielding sheet is an overflow part. A groundwater tank filled with a rectangular beam body and a plurality of support legs that support the beam body inside uses a groundwater tank filler that has a very high pressure resistance. Suitable for places where load is applied such as under. Moreover, the magnitude | size of a storage part can be arbitrarily set by using a filler. In this way, even in the case of a groundwater tank filled with a filler consisting of a beam body and support legs inside the storage part, as described above, the effect of not being damaged even if there is a hard thing at the time of earth pressure equalization or backfilling Play.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  1 is a schematic cross-sectional view showing a groundwater tank according to an embodiment of the present invention, FIG. 2 is a perspective view of a water tank that is a constituent member of the groundwater tank, and FIG. 3 is a water flow / permeability that is a constituent member of the groundwater tank. FIG. 4 is a partial cross-sectional view of the water-permeable / water-permeable sheet, showing a state before the sheet is coated with a water-permeable coating material.

  The underground water tank T1 of the present invention is suitably provided in the basement of parking lots, parks, gardens, and the like. As shown in FIG. 1, the storage tank 1 for storing rainwater and the upper part of the storage section 1 are provided. In addition, a plurality of overflow portions 2 and a water / permeable sheet 3 attached around the storage portion 1 are configured. A side groove 5 is formed around the groundwater tank T1, and an overflow pipe 5a for discharging rainwater overflowing from the reservoir 1 is connected to the upper side of the side groove 5. A mesh part 5b is attached to the tip of the overflow pipe 5a, and the rainwater that has overflowed from the side groove 5 during heavy rain flows through the overflow pipe 5a and passes through the mesh part 5b. However, it flows into the reservoir 1 through the water intake inspection port 6.

The water intake inspection port 6 is provided with a water intake pipe 7 extending from an electric pump P that pumps up rainwater collected in the reservoir 1, and the rainwater pumped up by the electric pump P is used for car washing, watering, toilets, and the like. It can be done. In addition, an inspection port 8 having a diameter of about 200φ for inspecting the inside of the underground water tank T1 is provided in the upper part of the underground water tank T1, and the underground water tank T1 is inspected and maintained from the inspection port 8. Yes. And this inspection port 8 is connected with the front eaves 9 via the inflow pipe 8a, and the rain water which flowed into the front eaves 9 from the drain pipe 11 connected with the solid wall (not shown) of a house etc. , It flows into the reservoir 1. At this time, dust can be removed by the basket portion 9a of the front rod 9, and mud etc. settles in the mud reservoir at the lower portion of the front rod 9, so that only clean rainwater flows into the underground water tank T1. .
In this embodiment, the electric pump P is used to pump up rainwater, but it goes without saying that a manual pump may be used. Further, the front rack 8 may be any one as long as it is frequently used in the construction industry.

As shown in FIG. 2, the reservoir 1 is a resin water tank 1 having a concave cross section with an open top, and a plurality of front side upper parts, right side upper parts, left side upper parts, and rear side upper parts are spaced apart from each other by a predetermined interval. The hole (overflow part 2) is perforated. Even if a large amount of rainwater exceeding the amount of water stored in the water tank 1 flows into the water tank 1, the overflow water is discharged to the outside. The overflow portion 2 is formed about 0 cm to 20 cm below the upper end of the water tank 1.
Although the dimension of this water tank 1 is not specifically limited, A width | variety of 0.5 m-50 m, a length of 1 m-50 m, and a depth of about 0.5 m-3 m are used suitably. A plurality of overflow portions may be formed, or one overflow portion may be provided. Moreover, you may provide in the upper part of the storage tank 1, you may provide in a top | upper surface, and there exists the same effect even if it provides in both. In addition, when the water tank 1 is the above-mentioned size, considering the overflow amount of rainwater, the total opening area when a plurality of overflow portions 2 are provided is equal to the cross-sectional area of the inflow pipe or about twice the cross-section area of the inflow pipe it is desirably usually a 75cm ² ~1000cm ^2. Therefore, the opening area of the overflow portion one place is suitably 100mm ² ~1000mm ² (opening area becomes clogged by dust or the like is too small in the tank is too large outside the crushed stone or sand is in the tank Easier to enter). Moreover, although the water tank 1 of this embodiment is made of synthetic resin, it can also be formed of concrete or metal. When formed of synthetic resin, the thickness is slightly increased or the wall surface is ribbed to maintain strength. It is preferable to have a structure, or to fill the inside of the tank with a reinforcing material or to form a reinforcing beam.

Since the upper part of the water tank 1 is opened, it is necessary to cover the upper opening with some kind of lid as shown by the phantom line in FIG. Various lids are conceivable for covering the upper opening, so it is not particularly limited, but at least strength sufficient to withstand the earth pressure from above is necessary, for example, various lids on the market, A rectangular plate made of metal, concrete, synthetic resin or the like is preferably used.
Needless to say, the water tank 1 and the lid may be integrally formed.

  A water / permeable sheet 3 described below is attached to the lid that covers the five surfaces (front side surface, rear side surface, right side surface, left side surface, bottom surface) and upper opening of the water tank 1 configured as described above.

That is, the water-permeable / water-permeable sheet 3 shown in FIG. 3 is made of polyethylene (high-density polyethylene) or other thermoplastic resin, and a large number of hollow convex portions 3a having a shape similar to a frustoconical shape are resin. It protrudes alternately on both sides of the plate, forming a rainwater drainage space. As shown in FIG. 4, a large number of water permeable holes 3 b (two in one convex portion 3 a in this embodiment) are formed in the convex portion 3 a, and overflow from the overflow portion 2 of the water tank 1. Rainwater that flows through the drainage space and uniformly reaches the side and bottom of the water tank 1 and flows into the drainage space on the opposite side from the plurality of water permeable holes 3b in the middle of the flow path, and penetrates into the ground from there. To go. Therefore, since the surface integral of the side surface and the bottom surface of the water tank 1 acts as a permeation portion, the water permeability of the water-permeable coating material 4 to be described later that covers the water-permeable / permeable sheet 3 is high, The efficiency is very high and there is no worry of water overflowing from the underground water tank T1.
In addition, although the dimension of this water permeation / permeable sheet 3 is not particularly limited, a sheet having a width of 60 cm to 2 m and a length of about 1 m to 50 m is preferably used in relation to the water tank 1. Further, the water / permeable sheet 3 is effective as long as the convex portion 3a is provided at least on the side in contact with the water tank 1, but the convex portion 3a is provided on both sides as in the present embodiment. It is more preferable because it has higher pressure resistance and drainage spaces through which rainwater flows are formed on both sides.

  As shown in FIG. 4, both surfaces of the water-permeable sheet 3 are covered with a water-permeable coating material 4. In this covering method, the water-permeable / permeable sheet 3 may be covered with a water-permeable coating material 4 attached to each side of the water-permeable / permeable sheet 3 as in this embodiment. It is preferable that it is surrounded by a water-permeable covering material 4 and pasted with a cloth adhesive tape 4a so that there is no gap between the ends, or by heat sealing so that the connection can be made easily. Furthermore, workability | operativity improves more by sticking the water-permeable sheet 3 and the water-permeable coating | covering material 4 with an adhesive tape, or joining by heat sealing | fusion.

As the water-permeable coating material 4, a nonwoven fabric or a woven fabric of a synthetic resin fiber such as polypropylene fiber having a high tear strength is preferably used. Such a water-permeable coating material 4 is excellent in water permeability and prevents invasion of soil particles. Nevertheless, clogging is less likely to occur, and the effect of promptly passing rainwater to the drainage space of the water permeable sheet 3 is achieved.
The water-permeable covering material 4 is not necessarily required to cover both sides of the water-permeable / water-permeable sheet 3, but it is effective if only the portion in contact with the soil side is covered. In order to prevent this, it is preferable to cover both surfaces of the water / permeable sheet 3.

The height of the projection 3a, the diameter of the tip of the projection 3a, the pitch between the projections 3a, 3a, etc. are not particularly limited, but considering the drainage capacity, strength, etc., the height of the projection 3a is 5 mm to 50 mm. extent, the area of 10mm ² ~250mm ² about the convex portion 3a tip, it is desirable to set the projecting portions 3a, the pitch between 3a to about 10Mm～110mm. If the height of the protrusion 3a protrusion is lower than 5 mm and the pitch between the protrusions 3a and 3a is smaller than 10 mm, the drainage space between the protrusion 3a and the protrusion 3a becomes too small, resulting in a decrease in drainage capacity. If the height of the convex portion 3a is higher than 50 mm and the pitch interval between the convex portions 3a and 3a is larger than 110 mm, the drainage space between the convex portions 3a and 3a becomes larger. Therefore, the water-permeable coating material 4 to be described later is pushed into the drainage space by the earth pressure, resulting in a disadvantage that the drainage space becomes small or the water-permeable coating material 4 is torn. . In addition, if the area of the tip of the convex portion 3a is smaller than 10 mm ² , the water-permeable covering material 4 is easily damaged by the convex portion 3a when earth pressure acts, which is also not preferable. Although the convex part 3a does not need to be hollow, if the solid convex part 3a is formed, the weight increases and it becomes difficult to carry, and the cost increases due to an increase in the amount of resin used. Is desirable. Further, the shape of the convex portion 3a is not limited to the shape similar to the truncated cone shape, and may be a cone shape, a truncated pyramid shape, a pyramid shape, or any other arbitrary shape. If the shape is similar to the truncated conical shape, the moldability and pressure resistance are improved, the earth pressure is not transmitted to the outer wall surface of the water tank in a point load, and the drainage flow resistance is reduced. Since there exists an advantage that drainage property improves, it is preferable.

If the convex portion 3a has the dimensions as described above, the pressure-resistant strength is 15 tf / m ^{2 to} 50 tf / m ² and has a very high pressure-resistant performance. Therefore, the convex portion 3a may be damaged even under high pressure in the soil. Absent. Moreover, since it is lightweight and flexible, it can be easily and easily cut and connected.

  An example of the construction procedure of the underground water tank T1 composed of the above members will be described.

First, the ground G is excavated to secure a space for embedding the water tank 1. Then, the water-permeable / water-permeable sheet 3 covered with the water-permeable coating material 4 is laid on the side surface and the bottom surface of the space. At this time, it is preferable that the water / permeable sheet 3 is also attached to the top surface of the water tank 1, so that the water / permeable sheet 3 laid on the side surface is folded back and attached to the top surface of the water tank 1 as much as possible. It is preferable to lay it down.
In addition, when the water-permeable / permeable sheet 3 is not long enough and the water-permeable / permeable sheets 3 are connected to each other, the water-permeable covering material 4 is peeled off once, and the protrusions at both ends of the water-permeable / permeable sheet 3 are projected. After the portions 3a and 3a are fitted to each other, the overlapped portion of the water-permeable covering material 4 can be simply performed by stopping with the cloth adhesive tape 4a. Moreover, although the water permeation / permeable sheet 3 can be attached to the water tank 1 from the beginning, this construction procedure is preferable in consideration of workability.

Next, the water tank 1 is installed in the excavation space, and the water flow / permeable sheet 3 is attached to the side surface and the bottom surface of the water tank 1. And after arrange | positioning the various members (the overflow pipe 5a, the water intake inspection port 6, the pump, the water intake pipe 7, the inspection port 8 etc.) mentioned above, while covering the upper opening of the water tank 1 with a lid | cover, surplus water flow and water permeability The sheet 3 is folded back, attached to the upper opening (top surface portion), and covered with soil from above.
The drainage / water-permeable sheet 3 can maintain good drainage as long as it covers at least the part below the overflow part 2, but if it covers the lid of the upper opening of the water tank 1 as in this embodiment, In this case, it is preferable to cover the upper opening (top surface portion) of the water tank 1 as much as possible because there is no risk of the lid being damaged by soil or stone.

  As is clear from the above description, the underground water tank T1 of the present invention is simply constructed by excavating the ground and filling the water tank 1 with the water-permeable / permeable sheet 3 attached in the space, and withstand pressure. Excellent in durability and durability. And even if rainwater overflows from the overflow part 2 of the water tank 1 due to heavy rain or the like, the rainwater flows through a drainage space formed by a large number of convex parts 3 a of the water flow / permeable sheet 3 and is uniformly on the side surface and bottom surface of the water tank 1. And penetrates into the ground through the water-permeable holes 3b of the water-permeable / water-permeable sheet 3 formed in the middle of the flow path. Therefore, since the surface integral of the side surface and the bottom surface of the water tank 1 acts as a permeation portion, the drainage efficiency is very high, and there is no fear that water overflows from the underground water tank. And since the water-permeable coating | covering material 4 exhibits high filter performance and is excellent in durability, it can maintain high performance over a long period of time. Moreover, since the lower part from the overflow part 2 can be utilized as a storage space, the ratio of the storage volume with respect to the underground water tank T1 is very large.

  FIG. 5 is a schematic cross-sectional view of a groundwater tank according to another embodiment of the present invention, FIG. 6 is a perspective view of a filling material for a groundwater tank that is a component of the groundwater tank, and FIG. FIG. 8 is a partially enlarged perspective view showing a state before the filler is connected up and down.

  In the groundwater tank T2 of this embodiment, as shown in FIG. 5, the water-permeable / permeable sheet 3 described above is laid in a space excavated from the ground G, and a rubber sheet or the like is shielded from above the water-permeable / permeable sheet 3. The reservoir 10 is formed by covering the water sheet 30. At this time, it is preferable that the water-permeable / permeable-sheet 3 is laid with a surplus enough to be folded and attached to the upper surface of the reservoir 10 in the same manner as the groundwater tank T1 described above. Further, the water shielding sheet 30 is not covered to the limit of the upper end of the storage unit 10, and is covered so as to leave a little upper part in order to secure a space for overflowing rainwater. In this way, the water-permeable / permeable sheet 3 is provided between the water-impervious sheet 30 and the soil surface, and the water-impervious sheet 30 is covered by leaving the upper part of the reservoir 10 a little, thereby storing the water-impervious sheet 30 from the upper end. Up to the upper surface of the part 10 is an overflow part 20 for draining rainwater. The rainwater overflowing from the overflow portion 20 spreads uniformly on the side surface and bottom surface of the storage portion 10 as in the above-described underground water tank T1, and the water-permeable holes 3b of the water-permeable / permeable sheet 3 formed in the middle of the flow path. Since it penetrates into the ground from the ground, drainage efficiency is very high and there is no need to worry about water overflowing from the underground water tank.

  In order to reinforce the reservoir 10 configured as described above, a groundwater tank filler 12 described below is used.

  That is, the groundwater tank filler 12 shown in FIG. 6 is a synthetic resin filler, and four support legs 14 are provided at four corners of a rectangular beam 13. Locking portions 13a are formed on two adjacent surfaces of the side surface of the beam body 13, and locked portions 13b are formed on the remaining two surfaces. Is formed with a rectangular concave hole 13c to be fitted to the support leg 14.

In order to fill the groundwater tank T2 with the groundwater tank filler 12 having the above structure, first, as shown in FIG. 7, the locking portion 13a and the locked portion 13b formed on the beam body 13 are locked. Then, the underground water tank filler 12 is connected to the left and right. Next, as shown in FIG. 8, the lower end portion of the support leg 14 and the concave portion 13 a of the beam body 13 are fitted to perform vertical connection. By repeating this operation, the underground water tank T2 is filled.
In addition, the filler 12 for groundwater tanks used by this embodiment is an example to the last, and is not limited to this filler 12 for groundwater tanks, Various fillers for groundwater tanks can be used. For example, when connecting the filler 12 for underground water tanks, the filler 12 which has the to-be-latched part 13b is connected, the connection piece member (not shown) whose cross section is H-shaped, The lower leg may be engaged with and engaged with the locked portion 13b and the locked portion 13b.

  As described above, after filling the groundwater tank T2 with the groundwater tank filler 12, a rectangular plate made of synthetic resin is placed on the topmost groundwater tank filler 12, and covered with soil. Thus, the underground water tank T2 is completed.

  Since the other structure of this underground water tank is the same as that of the ground water tank of embodiment shown in FIGS. 1-4 mentioned above, description is abbreviate | omitted.

  The underground water tank T2 having the above-described configuration is suitable for a place where a load is applied (such as under a parking lot) because the underground water tank filler 12 is very strong against the load from above. Further, by increasing or decreasing the number of fillers 12 for the underground water tank, it is possible to deal with various sizes of underground water tanks, and the size of the underground water tank T2 can be arbitrarily set.

  FIG. 9 is a schematic cross-sectional view of a groundwater tank according to still another embodiment of the present invention, FIG. 10 is a partially enlarged cross-sectional view showing an attached state of a thick nonwoven fabric or woven fabric that is a constituent member of the groundwater tank, and FIG. FIG. 3 is a perspective view of a net body that is a component of the underground water tank.

  In the underground water tank T3 shown in FIG. 9, a thick nonwoven fabric 3A is attached around the water tank 1 described above, and a net body N shown in FIG. 11 is attached from the outside of the thick nonwoven fabric 3A (side surface and bottom surface). Is. At this time, it is preferable that the thick non-woven fabric 3 </ b> A also has an extra space enough to be attached to the upper surface of the water tank 1 after the water tank 1 is buried, similarly to the above-described underground water tank T <b> 1.

The thick nonwoven fabric 3A is formed of a synthetic resin fiber such as polypropylene fiber having a high tear strength, similar to the water-permeable covering material 4 described above. As is well known, non-woven fabric has excellent water permeability, so it plays a role as a water-permeable / permeable sheet, but it ensures that the water-permeable part that is the flow path of rainwater and the water-permeable surface that is the infiltrating part that rainwater penetrates into the ground. In order to ensure, it is necessary to make the thickness much larger than ordinary nonwoven fabrics and woven fabrics, and if the thickness is less than 5 mm, a rainwater flow path is not sufficiently formed, so that a thickness of about 5 mm to 20 mm is preferable. used.
The thick non-woven fabric 3A has the same effect even if it is a thick woven fabric.

On the other hand, as shown in FIG. 11, the mesh body N is a synthetic resin mesh body having square corners formed of warp and weft. A bar-like projection N1 protrudes from the intersection of the warp and weft. It is installed. In order to attach the mesh body N to the thick nonwoven fabric 3A, as shown in FIG. 10, the periphery (side surface and bottom surface) of the thick nonwoven fabric 3A is surrounded by the mesh body N, and the rod-shaped protrusion N1 is attached to the thick nonwoven fabric 3A. Since it can be easily installed by piercing, fixing with a stopper or the like is unnecessary, and workability is good. Normally, simply attaching the thick nonwoven fabric 3A around the water tank 1 reduces the thickness of the thick nonwoven fabric 3A due to earth pressure, and the water permeability decreases accordingly. By attaching from the outside, as shown in FIG. 10, the tip surface of the rod-shaped protrusion N1 comes into contact with the water tank 1 and plays the role of a stick, so there is a concern that the thickness of the thick nonwoven fabric 3A is reduced by earth pressure. The water permeability can be ensured.
The size of the mesh body N is not particularly limited, but the height of the rod-shaped protrusion N1 needs to be the same or substantially the same as that of the thick nonwoven fabric 3A, so that the thickness of the mesh body N is about 1 mm to 5 mm. the extent, the thickness of the warp and weft of about 1 mm to 5 mm, the opening area of the square hole there is 100mm ² ~1000mm ² degree shall be suitably used.
In addition, when the net body N is made of a synthetic resin as in the present embodiment, it is easy to bend at the time of attachment, and because it is lightweight, workability is good and preferable. Needless to say, it is good. Moreover, as long as it has many rod-shaped protrusion N1 and a water permeable part, it is not limited to a net | network body, For example, a panel body may be sufficient.
Since the other structure of this groundwater tank is the same as that of the groundwater tank of embodiment shown in FIGS. 1-8 mentioned above, description is abbreviate | omitted.

  In the groundwater tank T3 having the above-described configuration, the thick nonwoven fabric 3A sufficiently plays a role as a water-permeable / permeable sheet having a water-permeable portion and a water-permeable surface, and is attached to the outside of the thick nonwoven fabric 3A. Since the net body N having the rod-shaped protrusions N1 prevents a decrease in the thickness of the nonwoven fabric 3A due to earth pressure, the same excellent effects as those of the above-described underground water tanks T1 and T2 are exhibited.

It is a schematic sectional drawing which shows the underground water tank which concerns on one Embodiment of this invention. It is a perspective view of the water tank which is a structural member of the groundwater tank. It is a disassembled perspective view which shows the state before coat | covering the water-permeable / permeable sheet which is a structural member of the same underground water tank with a water-permeable coating | covering material. It is a fragmentary sectional view of the water-permeable / permeable sheet. It is a schematic sectional drawing of the underground water tank which concerns on other embodiment of this invention. It is a perspective view of the filler for underground water tanks which is a structural member of the groundwater tank. It is a partial expansion perspective view which shows the state before connecting the said filler to front and rear, right and left. It is a partial expansion perspective view which shows the state before connecting the filler up and down. It is a schematic sectional drawing of the underground water tank which concerns on other embodiment of this invention. It is a partial expanded sectional view which shows the attachment state of the thick nonwoven fabric or woven fabric which is a structural member of the groundwater tank. It is a perspective view of the net body which is a component of the groundwater tank.

Explanation of symbols

T1, T2, T3 Groundwater tank 1 Reservoir (water tank)
DESCRIPTION OF SYMBOLS 10 Storage part 2, 20 Overflow part 3 Water-permeable / permeable sheet 3A Thick nonwoven fabric (or woven fabric)
30 Water-impervious sheet 3a Protruding part 3b Water-permeable hole 4 Water-permeable coating material (nonwoven fabric)
12 Filling material for underground water tank 13 Beam body 14 Support leg G Ground N Net body N1 Rod-like projection

Claims (8)

Rainwater to form a reservoir for reserving the underground, by providing an overflow portion to the upper side surface and / or top surface of the該貯reservoir, the top surface and the side surface and the bottom surface of該貯reservoir, the water passing portion and permeability surface An underground water tank, wherein a water / permeable sheet is attached to the top surface, and the water / permeable sheet on the top is attached by folding back the water / permeable sheet attached to the side surface .   The water flow / water permeable sheet has a sheet surface in which a plurality of water permeable holes are formed as a water permeable surface and a continuous space between a plurality of convex portions provided on both sides or one side. The groundwater tank according to claim 1, wherein a tip of the portion is attached so as to be positioned on the storage portion side.   The groundwater tank according to claim 1 or 2, wherein both sides or one side of the water / water-permeable sheet are covered with a water-permeable covering material.   4. The underground water tank according to claim 3, wherein the water-permeable covering material is a non-woven fabric or a woven fabric. The height of the convex part of the water-permeable / water-permeable sheet is 5 mm to 50 mm, the area of the convex part tip in contact with the storage part side is 10 mm ^{2 to} 250 mm ² , and the pitch between the convex parts is 10 mm to 110 mm The underground water tank according to claim 2 to 4.   The water-permeable / permeable sheet is a thick non-woven fabric or woven fabric, and a network body having a large number of rod-shaped protrusions or a panel body having a large number of rod-shaped protrusions and a water-permeable portion is attached to the outside. The groundwater tank according to claim 1.   The underground water tank according to any one of claims 1 to 6, wherein the storage part is a water tank made of concrete, metal, or synthetic resin.   The storage part is covered with a water shielding sheet except for the upper part of the side surface or / and the top surface part of the space formed in the ground, and the part not covered with the water shielding sheet is an overflow part. The groundwater tank according to any one of claims 1 to 6, wherein the groundwater tank is filled with a rectangular beam body and a plurality of support legs for supporting the beam body.

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