Water barrier device   

Abstract: A water bather device includes: a water storage portion provided under a passage and a water barrier portion. In a first state, the water barrier wall is suspended and supported by the lid portion such that a space is formed by a lower end portion of the water barrier wall, a bottom surface of the water storage tank, and a side wall of the water storage tank. In a second state, the water barrier wall projects with respect to the passage through the opening. A first discharge port is connected is formed at a portion of the side wall of the water storage tank, the portion constituting the space, and a bottom surface of the water storage tank is inclined so as to become lower toward the first discharge port in a transverse direction of the passage.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a water barrier device configured to block the flow of water toward residential areas and the like at the time of tsunamis and floods.

2. Description of Related Art

To prevent the residential areas and the like from being flooded by tsunamis or floods, it is effective to construct banks at the seaside or riverside. However, if the banks are constructed, traffic is blocked by the banks. Therefore, normal living environment may deteriorate. Conventionally, a part of the banks is cut out, a passage is provided thereat, and a sliding type watertight door is provided on the passage. At normal times, the watertight door is open, and vehicles and people can go therethrough. If there is a possibility that tsunamis, floods, or the like may occur, the watertight door is closed, and the ingress of water into the residential areas and the like is prevented. However, the problems are that: in the case of moving the watertight door by humans, the opening and closing of the watertight door cannot be performed quickly; and in the case of moving the watertight door by electric power (a motor or the like), the watertight door does not move in the event of power outage.

Here, various water barrier device capable of operating quickly and surely have been developed. Japanese Laid-Open Patent Application Publication No. 7-197751 describes one example of such water barrier devices. The water barrier device described in the above publication is configured such that: an underground pit is formed under the ground level; a float and a tide prevention plate are accommodated in the underground pit; water having flowed into the underground pit floats the float and the tide prevention plate; and thus, the tide prevention plate projects at the passage located above the underground pit. In the above publication, the name “tide of wave preventing device” is used. However, this “tide of wave preventing device” is one type of “water barrier device” configured to block the flow of water.

According to the tide of wave preventing device (that is, the water barrier device) described in the above publication, the underground pit receives the water flowing from the sea or river at the time of tsunamis or floods, and the float and the tide prevention plate move up by utilizing buoyant force of the water. Therefore, the tide of wave preventing device can operate quickly and surely without relying on humans or electric power. However, since the float and the tide prevention plate are sandwiched between a metal cover plate and a bottom surface of the underground pit made of ferroconcrete at normal times, there is no place to which the impacts transferring from the vehicles and the like to the cover plate can escape, and there is a possibility that the impacts may damage the float and the tide prevention plate.

SUMMARY

An object of the present invention is to provide a water barrier device capable of being prevented from being damaged by impacts from vehicles and the like.

A water barrier device according to the present invention includes: a water storage portion provided under a passage where people and vehicles go through; and a water barrier portion accommodated in the water storage portion so as to be able to appear with respect to the passage, wherein the water storage portion includes: a water storage tank configured to store water and be formed to extend in a transverse direction of the passage; a water intake portion through which the water is taken in the water storage tank; and an opening which is open on an upper portion of the water storage tank toward the passage, the water barrier portion includes: a water barrier wall configured to appear with respect to the passage through the opening; a float portion formed integrally with the water barrier wall and configured to receive buoyant force from the water, stored in the water storage tank, to move up together with the water barrier wall; and a lid portion provided at an upper portion of the water barrier wall and configured to open and close the opening in accordance with up-down movements of the float portion and the water barrier wall, in a first state where the water is not stored in the water storage tank, the lid portion contacts an inner peripheral portion of the opening to close the opening, and the water barrier wall is suspended and supported by the lid portion such that a space is formed by a lower end portion of the water barrier wall, a bottom surface of the water storage tank, and a side wall of the water storage tank, in a second state where the water is stored in the water storage tank, the lid portion and the water barrier wall move up together with the float portion, and thus the water barrier wall projects with respect to the passage through the opening, and a first discharge port to which a first discharge pipe through which the water stored in the water storage tank is discharged is connected is formed at a portion of the side wall of the water storage tank, the portion constituting the space, and a bottom surface of the water storage tank is inclined so as to become lower toward the first discharge port in the transverse direction of the passage.

According to this configuration, in the first state where the water is not stored in the water storage tank, the lid portion contacts the inner peripheral portion of the opening. Thus, the passage is opened, and the opening is closed. In addition, the space is secured between the lower end portion of the water barrier wall and the bottom surface of the water storage tank, and the movements of the lower end portion of the water harrier are allowed in this space. Therefore, even in a case where impacts are applied to the lid portion from people or vehicles going through the passage, the impacts can be absorbed by the movements of the lower end portion of the water barrier wall. Thus, the water barrier wall and the float portion can be prevented from being damaged by the impacts. In contrast, in the second state where the water is stored in the water storage tank, the lid portion and the water barrier wall move up together with the float portion. Thus, the water barrier wall projects toward the passage through the opening, and the passage is closed. Therefore, the flow of the water flowing through the passage can be blocked quickly and surely without relying on humans or electric power. Moreover, according to this configuration, the space is formed by the lower end portion of the water barrier wall, the bottom surface of the water storage tank, and the side wall of the water storage tank, and the first discharge port to which the first discharge pipe is connected is formed at the portion of the side wall of the water storage tank, the portion constituting the space. Therefore, while applying the pressure to the water in the space by the weight of the water barrier portion, the water can be discharged through the first discharge pipe in a short period of time. Further, according to this configuration, the water stored in the water storage tank can be guided to the first discharge port and the first discharge pipe by the inclined bottom surface of the water storage tank.

The water barrier wall may include two wall plates arranged in parallel with each other, and the float portion may be arranged between these two wall plates.

According to this configuration, since the float portion is arranged between two wall plates constituting the water barrier wall, the vertical length of a portion where the water barrier wall and the float portion overlap can be shortened. Thus, the entire device can be reduced in size. In addition, the strength of the water barrier wall earl be increased by these two wall plates.

A second discharge port to which a second discharge pipe through which the water stored in the water storage tank is discharged is connected may be formed at the portion of the side wall of the water storage tank, the portion constituting the space, a lowest point of the second discharge port may be higher in position than a lowest point of the first discharge port, and a valve configured to block the flow of the water according to need may be provided on the first discharge pipe.

According to this configuration, by operating the valve to open the first discharge pipe, the water stored in the water storage tank can be discharged. In addition, at normal times, the valve of the first discharge pipe is closed, and the rain water and the like can be discharged through the second discharge port.

The above and further objects and features of the invention will more fully be apparent from the following detailed description with reference to accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the configuration of a water barrier device according to Embodiment 1.

FIG. 2 is a cross-sectional view showing a usage state (first state) of the water barrier device according to Embodiment 1.

FIG. 3 is an exploded perspective view showing the configuration of the water barrier device according to Embodiment 1.

FIG. 4 is a front view showing the configuration of the water bather device according to Embodiment 1.

FIG. 5A is a front view showing the configuration of a water barrier portion of the water barrier device according to Embodiment 1.

FIG. 5B is a rear view showing the configuration of the water bather portion of the water barrier device according to Embodiment 1.

FIG. 6C is a right side view showing the configuration of the water barrier portion of the water barrier device according to Embodiment 1.

FIG. 6D is a cross-sectional view taken along line VID-VID of FIG. 5A showing the configuration of the water barrier portion of the water barrier device according to Embodiment 1.

FIG. 7 is a partially enlarged cross-sectional view showing the usage state (first state) of the water barrier device according to Embodiment 1.

FIG. 8 is a partially enlarged cross-sectional view showing the usage state (second state) of the water barrier device according to Embodiment 1.

FIG. 9 is a partial cross-sectional view showing the configuration of the water barrier device according to Embodiment 2.

FIG. 10 is a partial cross-sectional view showing the configuration of the water barrier device according to Embodiment 3.

FIG. 11 is a front view showing the configuration of the water barrier device according to Embodiment 4.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments of the present invention will be explained in reference to the drawings.

FIG. 1 is a perspective view showing the configuration of a water barrier device 10 according to Embodiment 1. FIG. 2 is a cross-sectional view showing a usage state (first state) of the water barrier device 10. FIG. 3 is an exploded perspective view showing the configuration of the water barrier device 10. FIG. 4 is a front view showing the configuration of the water barrier device 10.

As shown in FIG. 2, the water barrier device 10 is configured to block the flow of water W toward a flooding prevention area S, such as a residential area, at the time of tsunamis or floods and includes a water storage portion 12 provided under a passage R and a water barrier portion 14 accommodated in the water storage portion 12. The passage R is provided at a place through which the water W flows toward the flooding prevention area S at the time of tsunamis or floods. At normal times, people and vehicles M (FIG. 7) can go through the passage R. As shown by arrows in FIG. 1, in the present embodiment, the upstream side and downstream side of the flow of the water W toward the flooding prevention area S respectively denote “front” and “rear”, and a right side and a left side when the water barrier device 10 is viewed from the upstream side respectively denote “right” and “left”.

As shown in FIG. 3, the water storage portion 12 includes: a water storage tank 20 configured to store the water W (FIG. 2); a first water intake portion 22 through which the water W is taken in the water storage tank 20 from above; a second water intake portion 24 through which the water W is taken in the water storage tank 20 from the front; an opening 26 which is open on an upper portion 20a of the water storage tank 20 toward the passage R; and a pair of guide portions 28a and 28b respectively provided on upper surfaces of both left-right-direction end portions of the water storage tank 20.

As shown in FIG. 1, the water storage tank 20 is a case-shaped member configured to receive and store the water W, which is flowing toward the flooding prevention area S, through the first water intake portion 22 and the second water intake portion 24. In the present embodiment, the water storage tank 20 is configured to extend across the passage R, be made of ferroconcrete, and be formed in a rectangular solid shape extending in a left-right direction. As shown in FIG. 4, an upper surface of a bottom plate 30 constituting a bottom portion of the water storage tank 20, that is, a bottom surface 30a of the water storage tank 20 is inclined so as to become lower from one longitudinal end portion thereof (in the present embodiment, a left end portion thereof) toward the other end portion thereof (in the present embodiment, a right end portion thereof). As shown in FIG. 3, a first discharge port 34 through which the water W stored in the water storage tank 20 is discharged is formed at a lower portion of a right end portion of a front side wall 32a of the water storage tank 20, and a second discharge port 36 through which the water W stored in the water storage tank 20 is discharged is formed at a lower portion of a left end portion of the front side wall 32a. As shown in FIG. 2, upper end edges of a rear side wall 32b, left side wall 32c, and right side wall 32d (FIG. 3) of the water storage tank 20 are arranged to be substantially the same in height as a passage surface G constituting the passage R, and an upper end edge of the front side wall 32a is arranged to be lower than the passage surface G.

As shown in FIG. 3, the first discharge port 34 is an opening through which the water W stored in the water storage tank 20 is discharged at once, and the diameter thereof is designed to be large so as to allow the water W to be discharged in a short period of time. An upstream end portion of a first discharge pipe 38 is connected to the first discharge port 34, and a valve 40 configured to block the flow of the water W according to need is provided on the first discharge pipe 38. At normal times, the valve 40 is closed so as to prevent the water W from flowing backward. When discharging the water W stored in the water storage tank 20, the valve 40 is opened manually or electrically. As shown in FIG. 2, a downstream end portion of the first discharge pipe 38 is open toward, for example, the sea.

As shown in FIG. 3, the second discharge port 36 is an opening through which, for example, rain water accumulated at normal times is discharged, and the diameter thereof is designed to be smaller than the diameter of the first discharge port 34. An upstream end portion of a second discharge pipe 42 is connected to the second discharge port 36, and a valve (not shown) configured to open and close a discharge passage is provided on the second discharge port 36 or the second discharge pipe 42. This valve is configured to open when the level of the water W stored in the water storage tank 20 is lower than a predetermined value and close when the level of the water W is equal to or higher than the predetermined value. At normal times, the valve opens to discharge, for example, the rain water through the second discharge pipe 42. As shown in FIG. 2, a downstream end portion of the second discharge pipe 42 is open toward, for example, the sea.

As shown in FIG. 2, the first water intake portion 22 includes: a bottom plate portion 22a formed to extend toward a front side from an upper end portion of the front side wall 32a of the water storage tank 20; and a front plate portion 22b formed to extend toward an upper side from a front end portion of the bottom plate portion 22a, and a water intake port 44 through which the water W is taken in is located on a rear side of an upper end portion of the front plate portion 22b so as to open toward the passage R. A lid member 46 is detachably arranged on an upper portion of the water intake port 44 so as to cover the water intake port 44. As shown in FIG. 3, the lid member 46 is a plate-shaped member including a plurality of water intake holes 46a through which the water W is taken in. The lid member 46 is made of, for example, metal having corrosion resistance so as to extend in the left-right direction.

As shown in FIG. 2, the second water intake portion 24 is a portion which receives the water W from a front side when the level of, for example, the sea rises up to a predetermined height H which is lower than the passage surface G. As shown in FIG. 3, the second water intake portion 24 includes a water intake pipe 24a having a rectangular cross-sectional shape extending in the left-right direction. As shown in FIG. 2, a downstream end portion of the water intake pipe 24a is connected to a portion of the front side wall 32a of the water storage tank 20, the portion being located to be spaced apart from the bottom surface 30a by a predetermined distance. An upstream end portion of the water intake pipe 24a is open toward, for example, the sea. Therefore, when the level of, for example, the sea rises up to the predetermined height H, the water W is taken in the water storage tank 20 through the water intake pipe 24a at once, and the level of the water W in the water storage tank 20 rises. A passage cross-sectional area of the water intake pipe 24a can be suitably adjusted by changing a left-right length thereof while maintaining constant a vertical length thereof.

As shown in FIG. 2, the opening 26 is a portion through which the water barrier portion 14 accommodated in the water storage tank 20 appears with respect to the passage R. As shown in FIG. 3, a front-rear length of the opening 26 is designed to be larger than a front-rear length of a water barrier wall 70 of the water barrier portion 14, and a left-right length of the opening 26 is designed to be larger than a left-right length of the water barrier wall 70. A rod-shaped front lid receiving portion 50 and a rod-shaped rear lid receiving portion 52, each of which constitutes a part of an inner peripheral portion 26a of the opening 26, are respectively provided on a front side and rear side of the opening 26 so as to extend in the left-right direction. Upper surfaces of the front lid receiving portion 50 and the rear lid receiving portion 52 are lid receiving surfaces 54 which receive a lid portion 74.

As shown in FIG. 3, the guide portions 28a and 28b are portions configured to guide in a vertical direction the water barrier portion 14 configured to appear with respect to the passage R through the opening 26. Each of the guide portions 28a and 28b includes: a supporting post portion 60 made of ferroconcrete and having a substantially U shape in plan view; and a guiding plate 62 made of metal and having a substantially U shape in plan view. Each of the supporting post portions 60 includes: a side plate 60a arranged continuously with respect to a structure, such as a bank; a front plate 60b arranged on a front side of the side plate 60a; and a rear plate 60c arranged on a rear side of the side plate 60a. Plate-shaped lid members 64 are respectively connected to upper end surfaces of the supporting post portions 60 by using bolts 66. Each of the guiding plates 62 is a member configured to cover an inner surface of the supporting post portion 60 and is formed by bending a metal plate. A guide rail 68 configured to guide the water barrier wall 70 is formed on an inner surface of the guiding plate 62 so as to extend in the vertical direction.

FIGS. 5A and 5B are diagrams each showing the configuration of the water hairier portion 14 of the water barrier device 10. FIG. 5A is a front view, and FIG. 5B is a rear view. FIG. 6C is a right side view, and FIG. 6D is a cross-sectional view taken along line VID-VID of FIG. 5A.

As shown in FIG. 3, the water barrier portion 14 includes: the water barrier wall 70 configured to appear with respect to the passage R through the opening 26; a float portion 72 formed integrally with the water barrier wall 70 and configured to receive the buoyant force from the water W stored in the water storage tank 20 to move up together with the water bather wall 70; and the lid portion 74 provided on an upper portion of the water barrier wall 70 and configured to open and close the opening 26 in accordance with up-down movements of the float portion 72 and the water barrier wall 70.

As shown in FIGS. 6C and 6D, the water barrier wall 70 includes two wall plates 76a and 76b arranged in parallel with each other. A peripheral portion of the wall plate 76a and a peripheral portion of the wall plate 76b are coupled to each other via a top plate 78a, a bottom plate 78b, a right side plate 78c, and a left side plate 78d. A division plate 80 including a hole 80a at the center thereof is horizontally arranged between two wall plates 76a and 76b. The division plate 80 divides an internal space of the water barrier wall 70 into an upper space 70a and a lower space 70b. Materials of respective components of the water barrier wall 70 are not especially limited. However, to effectively fulfill the function of blocking the flow of the water W, those materials are desirably high strength materials, such as aluminum alloy, stainless steel, fiber reinforced plastic, or plastic. In the present embodiment, the respective components are made of metal and are welded to one another to constitute the case-shaped water barrier wall 70.

As shown in FIG. 5A, a plurality of (in the present embodiment, two) projections 82a configured to contact the inner surface of the guiding plate 62 are provided on each of left-right-direction end portions of the surface of the wall plate 76a, located on a front side, so as to be spaced apart from each other in the vertical direction. As shown in FIG. 5B, a plurality of (in the present embodiment, two) projections 82b configured to contact the guide rail 68 are provided on each of left-right-direction end portions of the wall plate 76b, located on a rear side, so as to be spaced apart from each other in the vertical direction. Further, as shown in FIG. 5B, a packing 84 having a substantially U shape in rear view is provided in a region of the surface of the wall plate 76b located on the rear side, the region being located on a center side of the projections 82b.

As shown in FIG. 6D, the float portion 72 is arranged between two wall plates 76a and 76b and is a portion where the buoyant force is generated by the water W stored in the water storage tank 20. In the present embodiment, the float portion 72 is constituted by the upper space 70a, the lower space 70b, and a filler 86 filling the upper space 70a. The upper space 70a and the lower space 70b are configured to be airtight to prevent the air therein from leaking, and the buoyant force is obtained by this air. The upper space 70a is filled with the filler 86, such as urethane foam, which is light in weight. The upper space 70a is formed at a portion of the water barrier wall 70, the portion being to be projected toward the passage R, and the strength of this portion is increased by filling the upper space 70a with the filler 86.

When filling the upper space 70a with the filler 86, first, the water barrier wall 70 is prepared with the bottom plate 78b detached. Next, the upper space 70a is filled with the filler 86 through the hole 80a of the division plate 80. Then, the bottom plate 78b is welded to lower end portions of the wall plates 76a and 76b. At the time of the welding, welded portions are heated to a high temperature. However, since the heat can be released by, for example, the lower space 70b located between the bottom plate 78b and the upper space 70a, the heat deterioration of the filler 86 can be prevented.

As shown in FIGS. 5A and 5B, the lid portion 74 includes a plate-shaped lid main body 90 covering the opening 26 and a plurality of connection portions 92 detachably connecting the lid main body 90 to the upper portion of the water barrier wall 70.

As shown in FIG. 3, in a “first state” where the water W is not stored in the water storage tank 20, the lid main body 90 contacts the front lid receiving portion 50 and the rear lid receiving portion 52, which constitute the inner peripheral portion 26a of the opening 26. The shape of the lid main body 90 in plan view is designed in a rectangular shape extending in the left-right direction so as to correspond to the opening 26. The front-rear length of each of both left-right-direction end portions of the lid main body 90 is shorter, and these end portions are respectively arranged inside the guiding plates 62.

As shown in FIGS. 5A and 6D, each of the connection portions 92 includes: a projection-shaped first connection piece 94 provided on a side surface of the upper portion of the water barrier wall 70; and a projection-shaped or rod-shaped second connection piece 96 provided on a lower surface of the lid main body 90. The first connection piece 94 and the second connection piece 96 respectively include holes (not shown) which communicate with each other. A bolt 98a is inserted into these holes and threadedly engages with a nut 98b. Therefore, by detaching the nut 98b from the bolt 98a and pulling out the bolt 98a from the holes, the lid portion 74 can be detached from the water barrier wall 70.

As shown in FIG. 7, in a state where the lid portion 74 is attached to the water barrier wall 70, a length L0 from a lower surface of an outer peripheral portion of the lid main body 90 to a lower end of the water barrier wall 70 is designed to be smaller than a length L1 from the lid receiving surface 54 to an uppermost portion of the bottom surface 30a of the water storage tank 20. Therefore, in the “first state”, a lower end portion 70c of the water barrier wall 70 can be prevented from contacting the bottom surface 30a of the water storage tank 20. In addition, the movements of the lower end portion 70e of the water barrier wall 70 are allowed, and the impacts and vibrations applied to the water barrier wall 70 can be absorbed.

FIG. 7 is a partially enlarged cross-sectional view showing a usage state (first state) of the water barrier device 10. FIG. 8 is a partially enlarged cross-sectional view showing another usage state (second state) of the water barrier device 10.

As shown in FIG. 7, in the “first state” where the water W is not stored in the water storage tank 20, the water barrier wall 70 and the float portion 72 are completely accommodated in the water storage tank 20, and the lid portion 74 contacts the lid receiving surface 54 of the inner peripheral portion 26a of the opening 26. With this, the passage R is opened, and the opening 26 is closed. In addition, the water barrier wall 70 is suspended and supported by the lid portion 74 contacting the lid receiving surface 54. With this, a space Q is secured between the lower end portion 70c of the water barrier wall 70 and the bottom surface 30a of the water storage tank 20. Therefore, in the “first state”, people and the vehicles M can freely go through the passage R. In a case where the impacts are applied by people and the vehicles M to the lid portion 74, the lower end portion 70c of the water barrier wall 70 moves. Thus, the impacts can be absorbed. Therefore, the water barrier wall 70 and the float portion 72 can be prevented from being damaged by the impacts.

As shown in FIG. 2, in a case where the level of the water W in, for example, the sea rises up to the predetermined height H at the time of tsunamis or floods, the water W is taken in the water storage tank 20 through the water intake pipe 24a, and the level of the water W in the water storage tank 20 rises. That is, the water barrier device 10 becomes a “second state” where the water W is stored in the water storage tank 20. As shown in FIG. 8, in the “second state”, the float portion 72 receives the buoyant force from the water W stored in the water storage tank 20. Thus, the water barrier wall 70 and the lid portion 74 move up together with the float portion 72, and the water barrier wall 70 projects with respect to the passage R through the opening 26. With this, the passage R is closed, and the flow of the water W toward the flooding prevention area S is blocked. After that, if the level of the water further rises, and the water W flows on the ground surface, the water W is taken in the water storage tank 20 through the water intake port 44. When the water storage tank 20 is filled with the water W by the above inflow, a projecting length of the water barrier wall 70 with respect to the passage R is maintained constant, and the flow of the water W is blocked mainly by a portion, where the upper space 70a is faulted, of the water barrier wall 70. After the ater W on the ground surface recedes, the valve 40 is opened, and the water W in the water storage tank 20 is discharged through the first discharge pipe 38. When the discharge of the water W is completed, and the water barrier device 10 returns to the “first state”, the valve 40 is closed to prevent the water W from flowing backward through the first discharge pipe 38.

When, for example, the rain water flows into the water storage tank 20 through the water intake port 44 in the “first state”, the water W (including the rain water and the like) is stored in the space Q. When the level of the water W reaches the height of the second discharge port 36, the water W is discharged through the second discharge pipe 42. When, for example, garbage is accumulated in the space Q in the “first state”, the valve 40 is opened, and the garbage is discharged through the first discharge pipe 38 together with the water W in the space Q.

According to Embodiment 1, the water barrier portion 14 can be prevented from being damaged by the impacts from the vehicles M (FIG. 7) and can be used without any problem at places where the vehicles M go through.

The first discharge port 34 is fowled on a side of the space Q secured between the lower end portion 70c of the water barrier wall 70 and the bottom surface 30a of the water storage tank 20, and pressure can be applied to the water W in the space Q from above by the weight of the water barrier portion 14. Thus, the water W can be efficiently discharged through the first discharge port 34. In addition, since the bottom surface 30a of the water storage tank 20 is inclined so as to become lower toward the first discharge port 34, the water W can be efficiently discharged along the bottom surface 30a.

Further, since the float portion 72 is arranged between two wall plates 76a and 76b constituting the water barrier wall 70, the vertical length of a portion where the water barrier wall 70 and the float portion 72 overlap can be shortened. Thus, the entire device can be reduced in size.

FIG. 9 is a partial cross-sectional view showing the configuration of a water barrier device 100 according to Embodiment 2. In the water barrier device 100, a lid main body 106 of a lid body 104 constituting a water barrier portion 102 is formed to be bent in a circular-arc shape. The lid main body 106 in an arch shape extends between the front lid receiving portion 50 and the rear lid receiving portion 52. Therefore, the withstand load of the lid main body 106 can be improved while suppressing the increase in thickness of the lid main body 106. In FIG. 9, the same reference signs are used for the components corresponding to the components of the water barrier device 10 (the same is true for FIGS. 10 and 11).

FIG. 10 is a partial cross-sectional view showing the configuration of a water barrier device 110 according to Embodiment 3. In a water barrier portion 112 of the water barrier device 110, a lid main body 114a constituting a lid body 114 and a top plate 116a constituting a water barrier wall 116 are formed as one component, and the lid body 114 and water barrier wall 116 are integrally formed. Therefore, the number of parts of the water barrier portion 112 can be reduced, and the weight of the barrier portion 112 can be reduced. In addition, the manufacturing cost can also be reduced.

FIG. 11 is a front view showing the configuration of a water barrier device 120 according to Embodiment 4. In the water barrier device 120, a bottom surface 122a of a water storage tank 122 is inclined so as to become lower from both left-right-direction end portions thereof toward a left-right-direction center portion thereof, and the first discharge port 34 is provided at a lower portion of a left-right-direction center portion of a front side wall 122b of the water storage tank 122. To be specific, the bottom surface 122a of the water storage tank 122 is inclined so as to become lower toward the first discharge port 34 provided at the lower portion of the left-right-direction center portion of the front side wall 122b. Then, the second discharge port 36 and the first discharge port 34 are provided next to each other such that the lowest point of the second discharge port 36 is higher in position than the lowest point of the first discharge port 34. In Embodiment 4, the water W cart be efficiently discharged along the bottom surface 122a.

In Embodiment 1, the water storage tank 20 and the guide portions 28a and 28b are made of ferroconcrete, but the materials thereof are not limited to ferroconcrete. In another embodiment, the water storage tank 20 and the guide portions 28a and 28b may be made of metal having corrosion resistance.

In yet another embodiment, the upper space 70a and the lower space 70b may be used as spaces and may be filled with air or a gas other then air, or both the upper space 70a and the lower space 70b may be filled with the filler 86.

As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiments are therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.