JP7240279B2 - Underground reservoir - Google Patents

Description

The present invention relates to underground reservoirs.

A detention pond is a structure for flood control and prevention of river overflow. In a detention pond, for example, rainwater is temporarily stored (accepted) during torrential rain, and then released into a river or the like after the torrential rain has passed. Generally, a reservoir is constructed underground near the target river to receive water directly from the river and discharge it into the same river. Here, a reservoir constructed underground is called an "underground reservoir".

As for the underground reservoir, by setting the height of the inlet (receiving port) to the vicinity of the flood water level of the river, for example, during torrential rain, water from the river will flow in rapidly with a natural gradient. Since there is time to spare, water will be discharged from underground reservoirs by pumping and discharging into rivers. In addition, the upper surface of the roof of the underground reservoir is often covered with soil and used as a park.

Patent Literature 1 shows an example of an underground reservoir. Patent Literature 1 discloses an underground reservoir in which a large number of square chair-shaped blocks are arranged in the ground, and the blocks are entirely covered with a waterproof sheet and buried.

Japanese Utility Model Publication No. 06-013872

By the way, the inside of an underground reservoir is normally kept empty so that water from a river or the like can be stored during torrential rain, for example. In this regard, the underground reservoir must be constructed so that it does not float even if groundwater exists around the underground reservoir, which is empty inside. and increased construction costs.

An object of the present invention is to take countermeasures against groundwater in underground reservoirs in view of such circumstances.

Therefore, in the present invention, the underground reservoir is composed of an underground skeleton having an internal space capable of storing water, a drainage facility for discharging water in the underground skeleton to the outside of the underground skeleton, and an underground reservoir that penetrates the inside and outside of the underground skeleton. A groundwater introduction pipe provided in the skeleton for guiding groundwater around the underground skeleton into the underground skeleton, and a catchment layer for collecting groundwater flowing into the groundwater introduction pipe, wherein the catchment layer is the groundwater of the groundwater introduction pipe Adjacent to the inlet. The underground frame has a cylindrical side wall that has an inlet for water inflow and extends vertically in the ground, a roof that is provided so as to block the upper surface opening of the side wall, and is covered with a covering layer above. a bottom plate provided so as to block the lower opening of the side wall, wherein the internal space is surrounded by the side wall, the roof and the bottom plate.
In a first aspect of the invention, the groundwater introduction pipe is provided on the roof and at least part of the catchment layer is located on the roof.
In a second aspect of the invention, the groundwater introduction pipe is provided on the side wall and the catchment layer is adjacent to the outer peripheral surface of the side wall.

According to the present invention, the groundwater around the underground skeleton can flow into the underground skeleton through the groundwater introduction pipe. As a result, the groundwater level around the underground skeleton can be made about the installation height of the groundwater introduction pipe. In this way, groundwater countermeasures can be taken in the underground reservoir.

A diagram showing a schematic configuration of an underground reservoir in the first embodiment of the present invention AA sectional view of FIG. Partially enlarged view of part B of FIG. The figure which shows arrangement|positioning of the catchment layer and drain pipe in 2nd Embodiment of this invention. A diagram showing a schematic configuration of an underground reservoir in a third embodiment of the present invention CC sectional view of FIG. Partially enlarged view of portion D of FIG. The figure which shows the connection method of the side wall and earth retaining wall seen in the horizontal cross section in 4th Embodiment of this invention. The figure which shows the connection method of the side wall and the retaining wall seen in the vertical cross section in the said 4th Embodiment. A diagram showing a schematic configuration of an underground reservoir in a fifth embodiment of the present invention The figure which shows an example of the retaining wall in the said 5th Embodiment

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of an underground reservoir 1 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 3 is a partially enlarged view of portion B of FIG. In addition, in FIG. 2, illustration of the drainage equipment 20 is omitted for illustration simplification.

An underground reservoir 1 is provided close to a river 2 . The underground reservoir 1 includes a weir 3, an inflow pit 4, a retaining wall 5, and an underground skeleton 10. - 特許庁The weir 3 is made of concrete, for example, and is provided so as to face the bank of the river 2 . The upper end of the weir 3 is higher than the normal water level of the river 2 . When the water level of the river 2 rises due to torrential rain or the like and begins to exceed the flood water level, the water from the river 2 flows over the weir 3 into the inflow pit 4 . The inflow pit 4 is made of concrete, for example, and has a box shape with an open top. The bottom surface 4a of the inflow pit 4 is positioned at substantially the same height as the bottom surface of the inflow port 5a of the retaining wall 5 and the bottom surface of the inflow port 10a of the underground skeleton 10 . The water that has flowed into the inflow pit 4 over the weir 3 can flow into the internal space 10b of the underground skeleton 10 through the inflow ports 5a and 10a.

The earth retaining wall 5 is cylindrical and constructed to extend downward from the ground GL. The retaining wall 5 reaches the impermeable layer M of the ground G at its lower end. Here, the ground GL shown in FIG. 1 corresponds to the upper surface of the ground G. As shown in FIG. FIG. 1 shows the impermeable layer M of the ground G and the average groundwater level WL1. The average groundwater level WL1 is the average groundwater level of the ground G.

In this embodiment, the retaining wall 5 is cylindrical. The earth retaining wall 5 extends vertically in the ground (inside the ground G) and surrounds the outer periphery of the side wall 11, which will be described later. In this embodiment, the earth retaining wall 5 consists of a reinforced concrete continuous wall (RC continuous wall) constructed by a diaphragm continuous wall construction method. Here, in the diaphragm wall construction method, an RC wall is constructed in the ground G by inserting a reinforcing bar cage into an excavated trench excavated in the ground G using a stabilizing liquid and pouring concrete into the excavated trench. To construct.

In this embodiment, the diaphragm wall construction method is used as the construction method of the earth retaining wall 5, but the construction method of the earth retaining wall 5 is not limited to this. For example, as a construction method of the earth retaining wall 5, a soil mortar wall construction method such as the SMW construction method (registered trademark) or the TRD construction method (registered trademark) may be employed.
The earth retaining wall 5 has water impermeability. Therefore, the earth retaining wall 5 can function as a water impermeable wall.

The inflow port 5a of the earth retaining wall 5 communicates the inflow pit 4 with the inflow port 10a of the underground skeleton 10 . Although the cross-sectional shape of the inlet 5a of the retaining wall 5 is rectangular in this embodiment, the cross-sectional shape is not limited to a rectangular shape.

The underground skeleton 10 is built in the ground G within the area surrounded by the earth retaining wall 5 and above the impermeable layer M. The underground skeleton 10 includes a cylindrical side wall 11 , a roof 12 provided to close the upper opening of the side wall 11 , and a bottom plate 13 to close the lower opening of the side wall 11 .

In the present embodiment, the underground skeleton 10 is a strong plate type cylindrical/dome roof type. Here, the strength slab type is a type in which a lifting force from groundwater acts on the bottom slab 13 and groundwater pressure acts on the side wall 11 . Further, the structure type of the bottom plate 13 in this embodiment is also called a "rigid bottom plate type". In this embodiment, the bottom plate 13 is formed so as to be able to resist groundwater pressure due to its strength and weight. In addition, the dimensions of each part are determined so that the underground skeleton 10 does not float due to groundwater pressure.

In this embodiment the sidewall 11 is cylindrical. The side walls 11 are made of reinforced concrete, for example. The side wall 11 extends vertically in the ground (inside the ground G). The side wall 11 has a space (internal space 10b) in which water from the river 2 can be stored. The internal space 10 b is surrounded by the lower surface of the roof 12 , the inner peripheral surface of the sidewall 11 and the upper surface of the bottom plate 13 . In this embodiment, the height (vertical distance) of the internal space 10b is, for example, approximately 30 to 40 m, and the inner diameter of the side wall 11 is, for example, approximately 20 to 30 m. Further, in this embodiment, the thickness of the sidewall 11 is, for example, about 2 to 3 m.

The inlet 11 a of the side wall 11 that functions as the inlet 10 a of the underground skeleton 10 communicates the inlet 5 a of the earth retaining wall 5 with the internal space 10 b of the underground skeleton 10 . Although the cross-sectional shape of the inflow port 11a of the side wall 11 (the inflow port 10a of the underground skeleton 10) is rectangular in this embodiment, the cross-sectional shape is not limited to a rectangular shape.

The bottom slab 13 made of concrete, also called bottom slab concrete, is constructed on the excavated bottom surface 7 formed by excavating the inside of the earth retaining wall 5 prior to construction of the underground skeleton 10 . Although illustration is omitted, a crushed stone layer that can function as a water collecting layer may be formed between the excavated bottom surface 7 and the bottom slab 13 . Incidentally, in this embodiment, the thickness of the bottom plate 13 is, for example, about 4 to 6 m.

The roof 12 is a domed roof made of reinforced concrete, and is connected to the side wall 11 so as to close the top opening of the side wall 11 . In this embodiment, the air dome construction method (registered trademark) is used to construct the roof 12 (a domed roof made of reinforced concrete). In the air dome construction method (registered trademark), first, a film material (sheet) is placed, and air is supplied to the inside thereof to pressurize and inflate the film material. Next, a lath wire mesh is laid on the membrane material, and shotcrete is sprayed to form a mortar dome. Next, reinforcing bars are placed on the mortar dome, and concrete is placed and cured. In this way a roof 12 (a domed roof made of reinforced concrete) can be constructed. Although the roof 12 is a reinforced concrete dome roof in this embodiment, the roof 12 is not limited to a reinforced concrete dome roof.

In this embodiment, the roof 12 is curved in an upwardly convex arch shape (see FIG. 1), and has a circular shape in a plan view. The upper part of the roof 12 is covered with a cover layer 8. - 特許庁Excavated earth and sand generated by excavating the inside of the earth retaining wall 5 may be used for the covering soil layer 8 .

The underground reservoir 1 has an air supply/exhaust pipe 15 extending vertically through the cover layer 8 and the roof 12 . The air supply/exhaust pipe 15 communicates between the space above the ground GL (ground space) and the internal space 10b of the underground skeleton 10 . In this embodiment, the air supply/exhaust pipe 15 vertically penetrates the top (central portion) of the arched roof 12 . In this embodiment, the height of the inner surface of the top of the roof 12, the height of the lower end opening of the supply/exhaust pipe 15, and the height of the upper end of the weir 3 are substantially the same.

When the water from the river 2 flows over the weir 3 into the inflow pit 4 and further flows into the internal space 10b from the inflow port 10a of the underground skeleton 10, the air in the internal space 10b of the underground skeleton 10 flows through the supply and exhaust pipe. 15 to the ground space. Therefore, the underground skeleton 10 can store water up to the height of the inner surface of the top of the roof 12 in its internal space 10b.

On the other hand, when the water stored in the internal space 10b of the underground skeleton 10 is discharged to the outside of the underground skeleton 10 (for example, the river 2) using the drainage equipment 20, the air in the aboveground space passes through the supply and exhaust pipe 15. It is supplied into the internal space 10b of the underground skeleton 10 . Therefore, it is possible to prevent the inside of the underground skeleton 10 from becoming negative pressure when the water stored in the underground skeleton 10 is discharged to the outside.

A drainage facility 20 is provided on the side of the inlet 10a of the underground skeleton 10 (that is, on the side of the river 2). The drainage facility 20 includes a vertically extending drainage pipe 21 and a drainage pump 22 suspended from the drainage pipe 21 . Although FIG. 1 shows an example in which the drainage facility 20 is composed of one drainage pipe 21 and one drainage pump 22, in reality, the drainage facility 20 has a plurality of (for example, four) drainage pipes. 21 , and a drain pump 22 is preferably suspended for each drain pipe 21 . The drainage pump 22 is arranged in a water collection pit 23 recessed on the upper surface of the bottom slab 13 on the side of the inlet 10a (that is, on the side of the river 2). The depth of the water collection pit 23 is, for example, about 1 m.

The drain pipe 21 extends from the underground skeleton 10 through the roof 12 and the covering layer 8 to the ground GL. By operating the drainage pump 22 of the drainage facility 20, the water stored in the internal space 10b of the underground skeleton 10 can be discharged to the outside of the underground skeleton 10 (for example, the river 2) through the drainage pipe 21. . A water level gauge (not shown) is installed in the drain pipe 21 . Therefore, it is possible to discharge the water in the internal space 10b while monitoring the water level in the internal space 10b of the underground skeleton 10 .

In this embodiment, a water collecting layer 25 is formed between a portion of the soil covering layer 8 adjacent to the retaining wall 5 and the upper end portion of the side wall 11 and the outer peripheral portion of the roof 12 . That is, at least part of the water collecting layer 25 is located on the roof 12 in this embodiment. The catchment layer 25 is formed below the average groundwater level WL1. The water collecting layer 25 is formed over the entire circumference of the sidewall 11 and the roof 12 . For example, the water collecting layer 25 may be crushed stone wrapped in a permeable sheet such as a civil engineering sheet. That is, the catchment layer 25 may contain crushed stone.

A plurality of drain pipes 27 are provided on the outer periphery of the roof 12 at predetermined intervals (for example, at intervals of 5 to 6 m) in the circumferential direction of the roof 12 . The drain pipe 27 penetrates the roof 12 and communicates the inside and outside of the underground skeleton 10 . That is, the drain pipe 27 is provided in the underground skeleton 10 so as to penetrate inside and outside the underground skeleton 10 . An upper end opening (groundwater inlet) of the drain pipe 27 faces the catchment layer 25 . In other words, the catchment layer 25 is adjacent to the upper end opening (groundwater inlet) of the drain pipe 27 . A lower end opening (groundwater outlet) of the drain pipe 27 faces the internal space 10b of the underground skeleton 10 .

The catchment layer 25 mainly has the function of collecting groundwater and rainwater described in (a) and (b) below.
(a) Leaks into the retaining wall 5 and passes through the water supply (water path) between the inner peripheral surface of the retaining wall 5 and the outer peripheral surface of the side wall 11 and / or the soil cover layer 8, and then the water catchment layer groundwater up to 25;
(a) Rainwater that falls on the soil covering layer 8 and reaches the catchment layer 25 through the soil covering layer 8 .
Here, the groundwater and rainwater described in (a) and (b) above are included in the "groundwater around the underground skeleton" of the present invention.

The drain pipe 27 guides groundwater and rainwater collected in the catchment layer 25 into the internal space 10b of the underground skeleton 10 . Therefore, in this embodiment, the drain pipe 27 corresponds to the "groundwater introduction pipe" of the present invention.

By the way, regarding the underground reservoir 1, the inside of the internal space 10b of the underground skeleton 10 is normally kept empty so that water from the river 2 can be stored, for example, during torrential rain. For this reason, normally, the above-mentioned groundwater and rainwater flowing into the internal space 10b of the underground skeleton 10 from the drain pipe 27 are discharged to the outside of the underground skeleton 10 (for example, the river 2) using the drainage facility 20. The inside of the internal space 10b of the underground skeleton 10 is maintained in an empty state. In this normal time, it is preferable to appropriately adjust the drainage capacity of the drainage facility 20 according to the amount of groundwater and rainwater flowing into the internal space 10b of the underground skeleton 10 from the drain pipe 27 . Specifically, for example, it is conceivable to appropriately increase or decrease the number of drain pumps 22 to be operated. Although it depends on the ground conditions, the above-mentioned groundwater and rainwater flowing into the internal space 10b is about 5 to 10 m ³ /day from examples of similar structures. , can be easily drained.

In this embodiment, groundwater and rainwater collected in the catchment layer 25 flow into the internal space 10b of the underground skeleton 10 through the drain pipe 27 . Therefore, the groundwater level WL2 in the earth retaining wall 5 is approximately equal to the height position of the upper end opening (groundwater inlet) of the drain pipe 27 (see FIG. 3). The groundwater level WL2 within the retaining wall 5 is lower than the average groundwater level WL1. Therefore, for the design of the underground skeleton 10, the groundwater level WL2 in the earth retaining wall 5, which is lower than the average groundwater level WL1, should be used as a reference. can be reduced).

According to this embodiment, the underground reservoir 1 includes an underground skeleton 10 having an internal space 10b capable of storing water from the river 2, and a drainage facility 20 for discharging the water in the underground skeleton 10 to the outside of the underground skeleton 10. and a drain pipe 27 (groundwater introduction pipe) provided in the underground skeleton 10 so as to penetrate inside and outside the underground skeleton 10 to guide groundwater around the underground skeleton 10 into the underground skeleton 10. As a result, the groundwater level around the underground skeleton 10 can be maintained at about the installation height of the drain pipe 27 .

Further, according to this embodiment, the underground reservoir 1 further has a catchment layer 25 that collects groundwater flowing into the drain pipe 27 (groundwater introduction pipe). A catchment layer 25 is adjacent to the upper end opening (groundwater inlet) of the drain pipe 27 . Therefore, groundwater collected in the catchment layer 25 can be smoothly guided to the drain pipe 27 .

Further, according to the present embodiment, the underground skeleton 10 has a cylindrical side wall 11 that has an inlet 11a into which water from the river 2 flows and extends vertically in the ground, and closes the upper opening of the side wall 11. It is provided with a roof 12 whose upper part is covered with a covering layer 8 and a bottom slab 13 provided so as to block the lower surface opening of the side wall 11. - 特許庁An internal space 10 b of the underground skeleton 10 is surrounded by the side walls 11 , the roof 12 and the bottom slab 13 . A drain pipe 27 (groundwater introduction pipe) is provided on the roof 12 , and at least part of the water collecting layer 25 is located on the roof 12 . Therefore, groundwater and rainwater collected in the catchment layer 25 can be smoothly guided into the internal space 10b of the underground skeleton 10 via the drain pipe 27 .

Further, according to this embodiment, the underground reservoir 1 further has a cylindrical retaining wall 5 that extends vertically in the ground and surrounds the outer periphery of the side wall 11 . The lower end of the retaining wall 5 reaches the impermeable layer M. Therefore, the groundwater level WL2 in the earth retaining wall 5 can be made approximately equal to the height position of the upper end opening (groundwater inlet) of the drain pipe 27 . Therefore, the groundwater level WL2 within the retaining wall 5 can be made lower than the average groundwater level WL1.

Further, according to this embodiment, the underground reservoir 1 includes an air supply/exhaust pipe 15 that penetrates the covering layer 8 and the roof 12 and communicates the space above the ground GL (ground space) with the internal space 10b of the underground skeleton 10. have more. Therefore, when the water stored in the internal space 10b of the underground skeleton 10 is discharged to the outside of the underground skeleton 10 (for example, the river 2) using the drainage facility 20, the air in the aboveground space passes through the supply and exhaust pipe 15. Since the water is supplied into the internal space 10b of the underground skeleton 10, it is possible to prevent the inside of the underground skeleton 10 from becoming negative pressure when the drainage equipment 20 drains water.

Moreover, according to this embodiment, the roof 12 is curved in an arch shape. A supply and exhaust pipe 15 passes through the top of the arched roof 12 . Therefore, when the water from the river 2 flows over the weir 3 into the inflow pit 4 and further flows into the internal space 10b from the inlet 10a of the underground skeleton 10, the air in the internal space 10b of the underground skeleton 10 is supplied. Since the water is discharged to the ground space through the exhaust pipe 15, the underground skeleton 10 can store water up to the height of the inner surface of the top of the roof 12 in the inner space 10b.

In this embodiment, since the retaining wall 5 is an RC continuous wall, it is possible to excavate the inside and construct the underground skeleton 10 without supports. In this regard, when the earth retaining wall 5 is a continuous wall of soil mortar, the construction of the side wall 11 is performed by the reverse winding construction method (the construction method of constructing the side wall 11 from top to bottom), so that the interior can be constructed without support. Excavation and construction of the underground skeleton 10 become possible.

In this embodiment, the air dome construction method (registered trademark) is used to construct the roof 12 . Therefore, the roof 12 can be constructed in a short time because no shoring for roof construction is required in a large space.

Next, a second embodiment of the invention will be described with reference to FIG. FIG. 4 is a diagram showing the arrangement of the water collection layer 26 and the drain pipe 27 in this embodiment. Here, FIG. 4 corresponds to portion B (FIG. 3) of FIG.
Differences from the first embodiment described above will be described.

In this embodiment, a water collecting layer 26 is formed between the outer peripheral surface of the upper end portion of the side wall 11 and the inner peripheral surface of the retaining wall 5 . That is, the water collecting layer 26 is adjacent to the outer peripheral surface of the side wall 11 and the inner peripheral surface of the retaining wall 5 . The catchment layer 26 is formed below the average groundwater level WL1. The water collecting layer 26 is formed on the outer peripheral surface of the upper end portion of the side wall 11 over the entire circumference. For example, the water collecting layer 26 is made of a water-permeable mat such as hechimaron (registered trademark). That is, the water catchment layer 26 may comprise a water permeable mat.

A plurality of drain pipes 27 are provided at the upper end of the side wall 11 at predetermined intervals (for example, at intervals of 5 to 6 m) in the circumferential direction of the side wall 11 . The drain pipe 27 extends in the radial direction of the side wall 11 and communicates between the inside and outside of the underground skeleton 10 through the side wall 11 . That is, the drain pipe 27 is provided in the underground skeleton 10 so as to penetrate inside and outside the underground skeleton 10 . One end opening (groundwater inlet) of the drain pipe 27 faces the catchment layer 26 . In other words, the catchment layer 26 is adjacent to one end opening (the groundwater inlet) of the drain pipe 27 . The other end opening (groundwater outlet) of the drain pipe 27 faces the internal space 10b of the underground skeleton 10 .

The catchment layer 26 mainly has the function of collecting groundwater and rainwater described in (c) and (d) below.
(c) Leaks into the retaining wall 5 and passes through the water supply (water path) between the inner peripheral surface of the retaining wall 5 and the outer peripheral surface of the side wall 11 and / or the soil covering layer 8, and then the water collecting layer groundwater down to 26;
(d) Rainwater that falls on the soil covering layer 8 and reaches the catchment layer 26 through the soil covering layer 8 .
Here, the groundwater and rainwater described in (c) and (d) above are included in the "groundwater around the underground skeleton" of the present invention.

The drain pipe 27 guides groundwater and rainwater collected in the catchment layer 26 into the internal space 10b of the underground skeleton 10 . Therefore, in this embodiment, the drain pipe 27 corresponds to the "groundwater introduction pipe" of the present invention.

In this embodiment, groundwater and rainwater collected in the catchment layer 26 flow into the internal space 10b of the underground skeleton 10 through the drain pipe 27 . Therefore, the groundwater level WL3 in the earth retaining wall 5 is approximately equal to the height position of one end opening (groundwater inlet) of the drain pipe 27 (see FIG. 4). The groundwater level WL3 within the retaining wall 5 is lower than the average groundwater level WL1. Therefore, for the design of the underground skeleton 10, the groundwater level WL3 in the earth retaining wall 5, which is lower than the average groundwater level WL1, should be used as a reference. can be reduced).

Normally, the above-mentioned groundwater and rainwater flowing into the internal space 10b of the underground skeleton 10 from the drain pipe 27 are discharged to the outside of the underground skeleton 10 (for example, the river 2) using the drainage facility 20. The interior space 10b of the frame 10 is kept empty.

Especially according to this embodiment, the drain pipe 27 (groundwater introduction pipe) is provided on the side wall 11 and the water collecting layer 26 is adjacent to the outer peripheral surface of the side wall 11 . Therefore, groundwater and rainwater collected in the catchment layer 26 can be smoothly guided into the internal space 10b of the underground skeleton 10 via the drain pipe 27 .

Next, a third embodiment of the invention will be described with reference to FIGS. 5 to 7. FIG. FIG. 5 shows a schematic configuration of the underground reservoir 1 in this embodiment. FIG. 6 is a cross-sectional view taken along line CC of FIG. FIG. 7 is a partially enlarged view of portion D of FIG. In addition, in FIG. 6, illustration of the drainage equipment 20 is omitted for illustration simplification.
Differences from the first embodiment described above will be described.

In this embodiment, the underground skeleton 10 is of a pumped cylindrical shape and a dome roof type. Here, the pumping type is a type in which groundwater pressure does not act on the bottom slab 13 and the side walls 11 . Further, the structural form of the bottom plate 13 in this embodiment is also called a "flexible bottom plate type". Therefore, in this embodiment, the thickness of the bottom plate 13 and the sidewalls 11 is thinner than in the first embodiment described above. In this embodiment, the thickness of the bottom plate 13 is, for example, about 1 to 2 m, and the thickness of the sidewall 11 is, for example, about 1 to 2 m.

Between the upper surface of the excavated bottom surface 7 and the lower surface of the bottom slab 13, a crushed stone layer 9 that can function as a water collecting layer is formed. That is, the crushed stone layer 9 is adjacent to the upper surface of the excavated bottom surface 7 and the lower surface of the bottom slab 13 . The crushed stone layer 9 can be formed by laying crushed stones on the excavation bottom surface 7 . The crushed stone layer 9 is formed below the average groundwater level WL1.

A plurality of drain pipes 27 are provided on the bottom plate 13 at predetermined intervals. The drain pipe 27 extends vertically, penetrates the bottom slab 13 , and communicates the inside and outside of the underground skeleton 10 . That is, the drain pipe 27 is provided in the underground skeleton 10 so as to penetrate inside and outside the underground skeleton 10 . A lower end opening (groundwater inlet) of the drain pipe 27 faces the crushed stone layer 9 . In other words, the crushed stone layer 9 is adjacent to the lower end opening (groundwater inlet) of the drain pipe 27 . An upper end opening (groundwater outlet) of the drain pipe 27 faces the internal space 10b of the underground skeleton 10 .

The crushed stone layer 9 mainly has the function of collecting groundwater and rainwater described in (e) and (f) below.
(e) Groundwater that leaks into the retaining wall 5 and reaches the crushed stone layer 9 through the waterway between the inner peripheral surface of the retaining wall 5 and the outer peripheral surface of the side wall 11 .
(f) Rainwater that falls on the covering soil layer 8 and reaches the crushed stone layer 9 through the covering soil layer 8 and the above-mentioned water supply.
Here, the groundwater and rainwater described in (e) and (f) above are included in the "groundwater around the underground skeleton" of the present invention.

The drain pipe 27 guides groundwater and rainwater collected in the crushed stone layer 9 into the internal space 10b of the underground skeleton 10 . Therefore, in this embodiment, the drain pipe 27 corresponds to the "groundwater introduction pipe" of the present invention.

Normally, by discharging groundwater and rainwater flowing into the internal space 10b of the underground skeleton 10 from the drain pipe 27 to the outside of the underground skeleton 10 (for example, the river 2) using the drainage facility 20, the inside of the underground skeleton 10 The space 10b is kept empty. Therefore, the groundwater level in the retaining wall 5 is, for example, slightly higher than the height of the upper end opening (groundwater outlet) of the drain pipe 27 . The groundwater level within this retaining wall 5 is lower than the average groundwater level WL1. Therefore, for the design of the underground skeleton 10, the groundwater level in the earth retaining wall 5, which is lower than the average groundwater level WL1, should be used as a reference, so the internal structure of the underground skeleton 10 is simplified (member dimensions are reduced). small).

Especially according to this embodiment, the drain pipe 27 (groundwater introduction pipe) is provided in the bottom slab 13 , and the crushed stone layer 9 (water catchment layer) is adjacent to the bottom surface of the bottom slab 13 . Therefore, groundwater and rainwater collected in the crushed stone layer 9 can be smoothly led into the internal space 10b of the underground skeleton 10 via the drain pipe 27 .

Next, a fourth embodiment of the invention will be described with reference to FIGS. 8 and 9. FIG. FIG. 8 is a diagram showing a method of connecting the side wall 11 and the earth retaining wall 5 in a horizontal cross section in this embodiment. FIG. 9 is a diagram showing a method of connecting the side wall 11 and the earth retaining wall 5 in a vertical cross section according to this embodiment. Here, in FIG. 8 , the left-right direction of the paper surface coincides with the circumferential direction of the side wall 11 and the retaining wall 5 . That is, in the illustration of FIG. 8, for convenience of explanation, the circumferential direction of the side wall 11 and the retaining wall 5 is linear, but in reality they are curved in an arc shape.
Differences from the above-described third embodiment will be described.

In this embodiment, the earth retaining wall 5 is a soil mortar continuous wall, and the side walls 11 are constructed by the reverse winding construction method. The earth retaining wall 5 includes a plurality of core members 30 made of H-section steel or I-section steel, for example. The core material 30 extends vertically.

In this embodiment, the base end of each of the plurality of stud bolts 31 is fixed to the flange adjacent to the side wall 11 of the core material 30 of the retaining wall 5 . In each core member 30, these stud bolts 31 are vertically spaced apart from each other. Most of each stud bolt 31 other than the base end portion is exposed to the outside of the retaining wall 5, and this exposed portion is caught in the side wall 11 when the side wall 11 is constructed. Therefore, the retaining wall 5 and the side wall 11 are integrated through the stud bolt 31 .

In this embodiment, the stud bolt 31 corresponds to the "connecting means" of the present invention and realizes the function of connecting the earth retaining wall 5 and the side wall 11 together. In addition, the "connecting means" of the present invention is not limited to the stud bolt 31, and may be, for example, a perforated plate. That is, a perforated plate may be fixed to the core member 30 instead of the stud bolts 31 .

Especially according to this embodiment, the underground reservoir 1 further has connecting means (for example, stud bolts 31 ) connecting the earth retaining wall 5 and the side wall 11 . As a result, the earth retaining wall 5 and the side wall 11 can be integrated, so that the earth retaining wall 5 can be prevented from opening due to an earthquake or the like, and the water impermeability of the earth retaining wall 5 can be maintained satisfactorily. be able to.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. 10 and 11. FIG. FIG. 10 is a diagram showing a schematic configuration of the underground reservoir 1 in this embodiment. FIG. 11 is a diagram showing an example of the earth retaining wall 5 in this embodiment. Here, in FIG. 11 , the left-right direction of the paper plane coincides with the circumferential direction of the earth retaining wall 5 . That is, in the illustration of FIG. 11, for convenience of explanation, the circumferential direction of the earth retaining wall 5 is linear, but actually it is curved in an arc shape.
Differences from the above-described third embodiment will be described.

In this embodiment, the inter-element joint structure of the earth retaining wall 5 made of RC continuous walls is a lap joint. FIG. 11 shows the lap joint where the reinforcing bar 35 a of the leading element 35 and the reinforcing bar 36 a of the trailing element 36 overlap at the lap joint portion 37 . By doing so, the retaining wall 5 also serves as the side wall 11 in this embodiment. That is, in the present embodiment, the side wall 11 that constitutes the underground skeleton 10 is omitted, and the earth retaining wall 5 plays that role. Incidentally, in this embodiment, the bottom plate 13 can be integrated with the retaining wall 5 .

In this embodiment, the joint structure between the elements of the mountain retaining wall 5 made of RC continuous wall is a lap joint, so that the side wall 11 is omitted. The side wall 11 may be omitted by using a cutting method for the joint and arranging RC ring beams on the inner surface thereof at intervals of about 5 m in the vertical direction. Also in this case, the bottom plate 13 can be integrated with the retaining wall 5 .

In the first to fifth embodiments described above, the drain pipe 27 is provided on any one of the side walls 11, the roof 12, and the bottom slab 13. As shown in FIG. In this regard, it is assumed that the drain pipe 27 corresponding to the "groundwater introduction pipe" of the present invention is provided on at least one of the side walls 11, the roof 12, and the bottom slab 13. In other words, when installing the drain pipe 27 corresponding to the "groundwater introduction pipe" of the present invention, it is conceivable to appropriately combine the aspects shown in the above-described first to fifth embodiments. For example, the drain pipe 27 may be provided on both the side wall 11 and the roof 12 by combining the first embodiment and the second embodiment described above. Further, for example, by combining the first embodiment and the third embodiment described above, the drain pipe 27 may be provided on both the roof 12 and the bottom plate 13 . Further, for example, the drain pipe 27 may be provided on both the side wall 11 and the bottom plate 13 by combining the second embodiment and the third embodiment described above. Further, for example, the drain pipes 27 may be provided on the side walls 11, the roof 12, and the bottom plate 13 by combining the first to third embodiments described above.

In the first to fifth embodiments described above, the cross-sectional shape of the cylindrical retaining wall 5 and the side wall 11 is circular, but the cross-sectional shape is not limited to circular, and may be elliptical or rectangular, for example. There may be. Also, the shape of the roof 12 in a plan view may be elliptical or rectangular, for example, corresponding to the cross-sectional shape of the cylindrical retaining wall 5 and side wall 11 . When the cross-sectional shapes of the cylindrical retaining wall 5 and the side wall 11 are rectangular, the roof 12 has a so-called semi-cylindrical shape.

In the above-described first to fifth embodiments, the water flowing into the internal space 10b from the inlet 10a of the underground skeleton 10 is from the river 2, but in addition, the water from the inlet 10a of the underground skeleton 10 to the internal space The water flowing into 10b may be from a pond or the like. That is, the water that can be stored in the underground reservoir 1 is not limited to the water from the river 2, and may be from a pond, for example.

The illustrated embodiments are merely illustrative of the present invention, and the present invention includes various improvements and modifications made by those skilled in the art within the scope of the claims in addition to those directly indicated by the described embodiments. It goes without saying that it is inclusive.
The claims as originally filed were as follows.
[Claim 1]
an underground skeleton having an internal space capable of storing water;
a drainage facility for discharging water in the underground skeleton to the outside of the underground skeleton;
a groundwater introduction pipe that is provided in the underground skeleton so as to penetrate the inside and outside of the underground skeleton and guides groundwater around the underground skeleton into the underground skeleton;
An underground reservoir.
[Claim 2]
further comprising a catchment layer for collecting groundwater flowing into the groundwater introduction pipe;
2. The underground reservoir of claim 1, wherein said catchment layer is adjacent to a groundwater inlet of said groundwater introduction pipe.
[Claim 3]
The underground skeleton is
a cylindrical side wall extending vertically through the ground and having an inlet into which water flows;
a roof provided to block the upper opening of the side wall and covered with a covering layer above;
a bottom plate provided to close the opening on the lower surface of the side wall;
with
the internal space is surrounded by the side wall, the roof and the bottom plate;
3. The underground reservoir according to claim 1, wherein said groundwater introduction pipe is provided on at least one of said side wall, said roof and said bottom slab.
[Claim 4]
The groundwater introduction pipe is provided on the roof,
4. An underground reservoir as claimed in claim 3 when claim 3 is dependent on claim 2, wherein at least a portion of said catchment layer is located on said roof.
[Claim 5]
The groundwater introduction pipe is provided on the side wall,
4. An underground reservoir as claimed in claim 3 when claim 3 is dependent on claim 2, wherein said catchment layer is adjacent to the outer peripheral surface of said sidewall.
[Claim 6]
The groundwater introduction pipe is provided in the bottom plate,
4. An underground reservoir as defined in claim 3 when claim 3 is dependent on claim 2, wherein said catchment layer is adjacent to the lower surface of said bottom slab.
[Claim 7]
further comprising a cylindrical retaining wall that extends vertically in the ground and surrounds the outer periphery of the side wall;
The underground reservoir according to any one of claims 3 to 6, wherein the lower end of the retaining wall reaches the impermeable layer.
[Claim 8]
8. The underground reservoir according to claim 7, further comprising connecting means for connecting said retaining wall and said side wall.
[Claim 9]
The underground reservoir according to any one of claims 3 to 8, wherein the roof is curved like an arch.
[Claim 10]
10. The underground reservoir according to any one of claims 3 to 9, further comprising an air supply/exhaust pipe penetrating the covering layer and the roof and communicating between the aboveground space and the internal space.
[Claim 11]
11. An underground reservoir as claimed in claim 10 when dependent from claim 9, wherein said supply and exhaust pipe passes through the top of said arched roof.

1... Underground reservoir, 2... River, 3... Weir, 4... Inflow pit, 4a... Bottom, 5... Retaining wall, 5a... Inlet, 7... Excavation bottom, 8... Soil cover layer, 9... Crushed stone layer (collection Water layer) 10 Underground skeleton 10a Inlet 10b Internal space 11 Side wall 11a Inlet 12 Roof 13 Bottom slab 15 Supply and exhaust pipe 20 Drainage facility 21 Drainage Pipe 22 Drainage pump 23 Water collection pit 25, 26 Water collection layer 27 Drain pipe 30 Core material 31 Stud bolt (connecting means) 35 Leading element 35a Reinforcing bar 36 ... trailing element, 36a ... reinforcing bar, 37 ... lap joint, G ... ground, GL ... ground, M ... impermeable layer, WL1 ... average groundwater level, WL2, WL3 ... groundwater level

Claims (7)

an underground skeleton having an internal space capable of storing water;
a drainage facility for discharging water in the underground skeleton to the outside of the underground skeleton;
a groundwater introduction pipe that is provided in the underground skeleton so as to penetrate the inside and outside of the underground skeleton and guides groundwater around the underground skeleton into the underground skeleton;
a catchment layer for collecting groundwater flowing into the groundwater introduction pipe;
has
the catchment layer is adjacent to the groundwater inlet of the groundwater introduction pipe;
The underground skeleton is
a cylindrical side wall extending vertically through the ground and having an inlet into which water flows;
a roof provided to block the upper opening of the side wall and covered with a covering layer above;
a bottom plate provided to close the opening on the lower surface of the side wall;
with
the internal space is surrounded by the side wall, the roof and the bottom plate;
The groundwater introduction pipe is provided on the roof,
An underground reservoir , wherein at least a portion of said catchment layer is located on said roof . an underground skeleton having an internal space capable of storing water;
a drainage facility for discharging water in the underground skeleton to the outside of the underground skeleton;
a groundwater introduction pipe that is provided in the underground skeleton so as to penetrate the inside and outside of the underground skeleton and guides groundwater around the underground skeleton into the underground skeleton;
a catchment layer for collecting groundwater flowing into the groundwater introduction pipe;
has
the catchment layer is adjacent to the groundwater inlet of the groundwater introduction pipe;
The underground skeleton is
a cylindrical side wall extending vertically through the ground and having an inlet into which water flows;
a roof provided to block the upper opening of the side wall and covered with a covering layer above;
a bottom plate provided to close the opening on the lower surface of the side wall;
with
the internal space is surrounded by the side wall, the roof and the bottom plate;
The groundwater introduction pipe is provided on the side wall,
An underground reservoir , wherein the catchment layer is adjacent to the perimeter of the sidewall . further comprising a cylindrical retaining wall that extends vertically in the ground and surrounds the outer periphery of the side wall;
3. The underground reservoir according to claim 1 , wherein the bottom end of said retaining wall reaches the impermeable layer. 4. The underground reservoir according to claim 3 , further comprising connecting means for connecting said retaining wall and said side wall. The underground reservoir according to any one of claims 1 to 4 , wherein the roof is curved like an arch. The underground reservoir according to any one of claims 1 to 5 , further comprising an air supply/exhaust pipe penetrating the covering layer and the roof and communicating the above-ground space and the internal space. 7. An underground reservoir as claimed in claim 6 when claim 6 is dependent on claim 5 , wherein said supply and exhaust pipe passes through the top of said arched roof.

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