JP2013221352A - Tsunami countermeasure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tsunami countermeasure for alleviating tsunami damage at a lower cost than a tsunami floodgate without requiring operation such as floodgate closing work when hit by the tsunami.SOLUTION: A tsunami countermeasure 10 comprises an impermeable wall 18 to reflect a high tidal wave TU fixed on a bottom of water 22 with piles 20. Being constructed in a marine area 16 facing a river mouth section 14, the impermeable wall 18 can be fixed with the piles 20 having large section areas without being subject to a limitation (no more than 4% of a section area of a river) applied when constructed in the river 12. A section deeper than a lower section of the impermeable wall 18 allows a wave or a water flow to pass through between the piles 20 which support the impermeable wall 18. Because the impermeable wall 18 can be constructed with a height of the lower section thereof higher than a predetermined tide level, the impermeable wall 18 can reflect the high tidal wave TU and prevent the same from attacking the river 12.

Description

  The present invention relates to a tsunami countermeasure work.

Conventionally, tsunami countermeasures have been developed to prevent tsunamis from entering the inland by flowing back through rivers and causing floods. As a general tsunami countermeasure, a tsunami sluice is installed at the estuary. There are some (see, for example, Patent Documents 1 and 2). In the case of this tsunami sluice, it is rare that a flood occurs at the same time as the tsunami in the design plan, and it is considered that there is no need for consideration. However, it is generally based on the design philosophy of giving priority to stopping the water level rise due to the tsunami attack and the break of the dike.

JP 2009-228330 A JP 2006-257716 A

Now, the tsunami sluice as described above has a large installation cost, and it is not realistic to install it in all rivers including small and medium rivers. Even if it can be installed, the work to close the sluice gate in the event of a tsunami entails a great risk, so it is extremely difficult to consider a quick and appropriate response to carry out the work.
The present invention has been made in view of the above problems, and its object is to reduce the cost of a tsunami without lowering the cost of the tsunami sluice and without performing operations when the tsunami strikes, such as a sluice gate closing work. It is to reduce the damage.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) In the sea area facing the estuary, an impervious wall for reflecting high tide waves is fixed to the bottom of the water by a pile so that the height of its lower end is higher than a predetermined tide level. Tsunami countermeasure work (Claim 1).
The tsunami countermeasure works described in this section are constructed by impermeable walls for reflecting high tide waves fixed to the bottom of the water by piles, and are installed in rivers by installing them in the sea area facing the estuary. The impervious walls are installed with piles with a large cross-sectional area without being restricted (within 4% of the cross-sectional area of the river). Examples of the impermeable wall used here include an RC wall constructed at the site or a PC wall carried into the site from a factory. The installation height and installation length of the impermeable wall are appropriately set in consideration of the topography of the installation site, the expected wave height, and the like. Moreover, a steel pipe pile etc. are mentioned as a pile used here. And in the part lower than the lower end portion of the impermeable wall, waves or water flows through the piles supporting the impermeable wall, but the height of the lower end portion of the impermeable wall is higher than a predetermined tide level. Therefore, even if a tsunami that exceeds the height of the impervious wall strikes, at least partially reaches the river. It will prevent and reduce disasters. In addition, the water flow from the river in normal times passes through the piles that support the impervious wall and diffuses offshore from the sea area facing the estuary.

(2) In the above item (1), a tsunami countermeasure work in which a slit wall extending to a height below the predetermined tide level is fixed along the lower side of the impermeable wall (claim 2).
The tsunami countermeasure works described in this section are fixed along the lower part of the impervious wall and are further extended by a slit wall extending to a height below a predetermined tide level. It partially obstructs the omission and at least partially prevents the arrival of high tide waves to the river, thereby achieving a disaster mitigating action. As for the slit wall, similarly to the impermeable wall, an RC wall constructed on site or a PC wall carried into the site from a factory can be used. And the slit wall may be integrated with the impermeable wall or may be a separate body. In the case of a separate body, the slit wall is directly fixed to the lower end portion of the impermeable wall or fixed via a pile. Is. In the latter case, a suitable gap may be provided between the impermeable wall. Furthermore, the opening shape and the opening area of the slit of the slit wall are appropriately set in consideration of the strength of the slit wall and the flow rate required for the slit. Similarly, the height of the lower end of the slit wall is also set as appropriate, and if necessary, comes into contact with the bottom of the water or extends further downward than the bottom of the water and is partially sunk in the bottom of the water. There may be. Then, the water flow from the river at normal time passes through the slit of the slit wall and diffuses from the sea area facing the estuary to the offshore.

(3) In the above items (1) and (2), the impermeable wall is installed in such a manner that the impermeable wall protrudes in an arc toward the offshore in a plan view (Claim 3).
The tsunami countermeasure work described in this section is installed in such a way that the impervious wall protrudes in an arc toward the offshore in plan view, regardless of the direction of the tsunami coming from offshore, The high tide wave is reflected by the impermeable wall, or the wave or water flow is inhibited by the slit wall at a portion lower than the lower end of the impermeable wall. The arc shape is appropriately set in such a manner that its curvature is constant or changes in consideration of the topography of the installation site, the expected wave height, and the like.

(4) In the above items (1) to (3), the impermeable wall is provided with a plurality of rows at intervals in the plan view toward the offshore (claim 4).
The tsunami countermeasure work described in this section is the opacity caused by the reflection of high tide waves by each of a plurality of rows of opaque walls arranged at intervals in the plan view, or by the slit walls. The wave or water flow inhibiting action at the lower part of the wall is exhibited. In this case, the installation intervals of the plurality of rows of impermeable walls are appropriately set in consideration of the topography of the installation site, the expected wave height, and the like.

(5) In the above items (1) to (4), a tsunami countermeasure work in which the predetermined tide level is a desired average high tide level in the sea area (Claim 5).
The tsunami countermeasure works described in this section will at least prevent the high tide level wave from reaching the river when a high tide level wave exceeding the normal tide level arrives due to the predetermined tide level being the envy average high tide level of the sea area. Partial prevention and disaster mitigation will be achieved.

(6) In the above paragraphs (1) to (5), a tsunami countermeasure work wherein the impermeable wall is installed in a river together with or in place of the sea area facing the estuary (claim 6).
When installing this tsunami countermeasure work in the sea area facing the estuary, it is reasonable to install it in the river even if it is restricted by the river if the installation range expands as necessary. Is also possible. Therefore, the tsunami countermeasure work described in this section exhibits the above-described disaster mitigation action by installing the impermeable wall in the river instead of the sea area facing the estuary. In addition, when installing an impermeable wall (and slit wall) in the river area, the cross-sectional area of the pillar that supports it is, of course, the limit for installation in a river (within 4% of the cross-sectional area of the river) Is set within.

  Since the present invention is configured as described above, it is possible to reduce the damage caused by the tsunami at a lower cost than the tsunami sluice and without performing an operation at the time of the tsunami intrusion such as a sluice deadline.

BRIEF DESCRIPTION OF THE DRAWINGS The tsunami countermeasure work which concerns on embodiment of this invention is shown, (a) is a sectional side view of the tsunami countermeasure work installed in the sea area which faces a river mouth part, (b) is the same front view. The tsunami countermeasure construction which concerns on the application example of embodiment of this invention is shown, (a) is a sectional side view of the tsunami countermeasure construction in the river mouth vicinity, (b) is the same front view. (A) is a plan view of the tsunami countermeasure work shown in FIG. 1 or FIG. 2, (b) is a plan view showing an example in which the tsunami countermeasure work is arranged in two rows at an interval toward the offshore. is there.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. Here, parts that are the same as or correspond to those in the prior art are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 1 shows a tsunami countermeasure work 10 according to an embodiment of the present invention. In this tsunami countermeasure work 10, an impermeable wall 18 for reflecting a high tide level wave TU in a sea area 16 facing an estuary part 14 of a river 12 has a lower end height higher than a predetermined tide level. Thus, the pile 20 is fixed to the bottom 22. Examples of the impervious wall 18 used here include an RC wall constructed on site or a PC wall carried into the site from a factory. Moreover, as the pile 20 used here, a steel pipe pile etc. are mentioned. Furthermore, in the example shown in FIG. 1B, the impervious wall 18 supported by the four piles 20 is one unit, and a mode in which a plurality of units (not shown) are continuous is shown. The configuration of one unit is set as appropriate (hereinafter the same applies to the example of FIG. 2).
And the envy average high tide level of the said sea area is set as a predetermined tide level which determines the height of the lower end part of impermeable wall 18. The installation height and installation length of the impermeable wall 18 are appropriately set in consideration of the topography of the installation site, the expected wave height, and the like.

Moreover, the application example of the tsunami countermeasure work 10 which concerns on embodiment of this invention is shown by FIG. In this example, a slit wall 24 extending to a height below a predetermined tide level is fixed along the lower side of the impermeable wall 18. In the example of FIG. 2, the slit wall 24 has an integral structure with the impermeable wall 18, but may be separate from the impermeable wall 18. In the case of a separate body, the slit wall 24 is fixed directly to the lower end portion of the impermeable wall 18 or is fixed via the pile 20. In this case, an appropriate gap may be provided between the impermeable wall 18.
Furthermore, the opening shape and opening area of the slit 24a of the slit wall 24 are appropriately set in consideration of the strength of the slit wall 24, the flow rate required for the slit 24a, and the like. Similarly, the height of the lower end portion of the slit wall 24 is also set as appropriate. In the example of FIG. 2, the lower end portion of the slit wall 24 is partially in contact with the inclined water bottom 22, but a gap may be provided between the slit wall 24 and the water bottom 22. Alternatively, the slit wall 24 may extend further downward than the water bottom 22 and be partially sunk in the water bottom 22.

Further, the impermeable wall 18 (and the slit wall 24) of the tsunami countermeasure work 10 shown in FIG. 1 or FIG. 2 draws an arc toward the offshore in a plan view as shown in FIG. It is installed in a protruding manner. In addition, as shown in FIG. 3B, there may be a case where the impermeable wall 18 (and the slit wall 24) are provided in two or more rows at an interval toward the offshore in a plan view. . The arc shape of the impermeable wall 18 (and the slit wall 24) is appropriately set in such a manner that its curvature is constant or changes in consideration of the topography of the installation site, the expected wave height, and the like. Further, the installation interval when a plurality of rows of impermeable walls 18 (and slit walls 24) are installed is also set as appropriate. In the illustrated example, both arc-shaped ends of the impermeable wall 18 (and the slit wall 24) are stopped at the sea area 16 facing the estuary 14 of the river 12, but extend to the land as needed. It is good also as installing.
Further, although not shown, the impermeable wall 18 (and the slit wall 24) of the tsunami countermeasure work 10 is installed in the river 12 together with the sea area 16 facing the estuary 14 or in place of the sea area 16. It is good as well. In this case, the cross-sectional area of the pillar that supports the impervious wall 18 (and the slit wall 24) of the tsunami countermeasure work installed in the river 12 is naturally limited to the restriction (if the cross-sectional area of the river) Within 4%).

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained. That is, the tsunami countermeasure work 10 according to the embodiment of the present invention is such that the impermeable wall 18 for reflecting the high tide level wave TU is fixed to the water bottom 22 by the pile 20 and faces the estuary 14. By installing in the sea area 16 that does not receive the restriction (within 4% of the cross-sectional area of the river) when the cross-sectional area of the pile 20 is installed in the river 12, the impervious wall with the pile 20 having a large cross-sectional area 18 can be installed. And in the part lower than the lower end part of the impervious wall 18, waves or water flows through the piles 20 that support the impermeable wall 18, but the lower end part of the impervious wall 18 has a height equal to or higher than a predetermined tide level. As shown in FIG. 1 (a), the high tide level wave TU is reflected by the impermeable wall 18 to prevent the high tide level wave TU from reaching the river 12. Can do.

Moreover, when the height of the lower end portion of the tsunami countermeasure work 10 is the envy average high tide level of the sea area 16, the arrival of the high tide level wave TU to the river 12 when a high tide level wave exceeding the normal tide level arrives. Can be prevented at least partially, and the necessary disaster mitigation effect can be obtained. Further, even if a high tide level wave TU exceeding the height of the impermeable wall 18 strikes, the momentum of the wave exceeding the impermeable wall 18 is reduced as shown by the dashed arrow in FIG. Thus, it is possible to partially prevent the storm surge wave from reaching the river 12.
On the other hand, as shown in FIG. 1 (a), the water flow WF from the river 12 in a normal time passes through the piles 20 that support the impermeable wall 18, and from the sea area 16 facing the estuary 14 to the offshore area. Will spread.

As shown in FIG. 2, when a slit wall 24 is provided which is fixed along the lower side of the impermeable wall 18 and extends to a height lower than a predetermined tide level, the slit wall 24 further causes the impermeable wall. The wave or water flow in a portion lower than the lower end portion of 18 is partially blocked, and at least partially prevents the arrival of a high tide level wave in the river, thereby further enhancing the disaster mitigation effect. Also in this case, the water flow from the river 12 at normal time passes through the slit 24a of the slit wall 24 and diffuses offshore from the sea area 16 facing the estuary.

  Further, as shown in FIG. 3 (a), the impermeable wall 18 (and the slit wall 24) is installed in such a manner that it projects in an arc toward the offshore in a plan view. Regardless of the tsunami intrusion direction, the high tide wave TU is reflected by the impervious wall 18, or the wave or water is blocked by the slit wall 24 at a portion lower than the lower end of the impermeable wall 18. Will be played. Therefore, the effect of preventing the high tide wave TU from reaching the river 12 can be further enhanced.

  Furthermore, as shown in FIG. 3 (b), if a plurality of rows of tsunami countermeasures 10 (10A, 10B) are provided at a distance from each other in plan view, 10A and 10B, the high tide wave TU is reflected by the impermeable wall 18, or the wave or water flow is blocked by the slit wall 24 at a portion lower than the lower end of the impermeable wall 18. This makes it possible to obtain further disaster reduction effects.

  In addition, when installing the tsunami countermeasure work 10 in the sea area 16 facing the estuary 14 when the installation range is expanded as necessary, it is installed in the river 12 even if it is restricted by the river. It is possible that this is reasonable. Therefore, the impermeable wall 18 (and the slit wall 24) may be installed in the river 12 instead of the sea area 16 facing the estuary 14. In addition, when installing the impermeable wall 18 (and slit wall 24) in the area | region of the river 12, the cross-sectional area of the pillar 20 which supports it naturally is a restriction | limiting (cross-sectional area of a river) when installing in a river. Within 4%).

  10, 10A, 10B: Tsunami countermeasures, 14: Estuary, 16: Sea area facing the estuary, 18: Impermeable wall, 20: Pile, 22: Water bottom, 24: Slit wall, 24a: Slit, TU: High Tidal wave

Claims (6)

In the sea area facing the estuary, the impervious wall for reflecting high tide level waves is fixed to the bottom of the water by a pile so that the height of its lower end is higher than the predetermined tide level. Tsunami countermeasure work. The tsunami countermeasure work according to claim 1, wherein a slit wall extending to a height lower than the predetermined tide level is fixed along the lower side of the impermeable wall. The tsunami countermeasure work according to claim 1 or 2, wherein the impermeable wall is installed so as to protrude in an arc toward an offshore in a plan view. The tsunami countermeasure work according to any one of claims 1 to 3, wherein the impermeable walls are provided in a plurality of rows at an interval toward an offshore in a plan view. The tsunami countermeasure work according to any one of claims 1 to 4, wherein the predetermined tide level is an enviable average high tide level of the sea area. The tsunami according to any one of claims 1 to 5, wherein the impermeable wall is installed in a river together with or in place of the sea area facing the estuary. Countermeasure work.

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