JP6616995B2 - Lifting pressure reduction device, lifting pressure reduction structure, and installation method of lifting pressure reduction device - Google Patents

Description

  The present invention relates to a lifting pressure reducing device, a lifting pressure reducing structure, and a method for installing the lifting pressure reducing device for a structure having a space where water enters due to tsunami, storm surge, flood, and the like.

  When waves and flows associated with tsunamis and storm surges, and waves and flows associated with river floods occur, structures constructed near the coast and rivers will suffer various damage due to inundation and water pressure. Patent Document 1 discloses a tsunami storm surge mitigation structure for preventing a disaster caused by such a tsunami.

  The tsunami storm surge mitigation structure of Patent Document 1 is provided with a water basin inside the box-shaped main body, and when waves flow into the water basin due to a tsunami or the like, the wave force and the air pressure increased in the water basin, The undulating end wall that becomes the ceiling surface of the water ditch room is configured to spring up.

  This undulating top wall is made of concrete and functions as a tide bank that suppresses the tsunami going up to the land side after undulation. In short, the lifting pressure that acts on the ceiling surface of the tsunami due to the tsunami is large enough to jump up the undulating end wall that is a heavy object.

JP 2012-97536 A

  However, when such a high lifting pressure acts on a normal structure, the structure may be broken or damaged, and some countermeasure is required. Near the coast are important waterfront facilities with intake and discharge channels such as power plants and industrial complexes, and piers. These structures are damaged by tsunamis, storm surges, river floods, etc. It is desirable to suppress as much as possible.

  Furthermore, buildings constructed on the coast may be designated as evacuation buildings during the tsunami attack, and it is necessary to minimize damage to the buildings that serve as evacuation destinations.

  Accordingly, an object of the present invention is to provide a lifting pressure reduction device, a lifting pressure reduction structure, and an installation method of the lifting pressure reduction device that can reduce the lifting pressure received from a tsunami or the like with a simple configuration.

  In order to achieve the above object, a lifting pressure reducing device of the present invention is a lifting pressure reducing device for a structure having a space into which water enters, a bag body portion filled with gas, and the bag body portion. And mounting means for mounting to the structure.

  Here, the bag body portion is provided with a hole communicating with the inside and outside of the bag body portion at least on the lower surface, and a suspension member constituting the attachment means is provided on the upper surface of the bag body portion. It can be set as a structure. Moreover, the inner space of the bag body portion may be divided into a plurality of sections.

  Furthermore, the invention of the lifting pressure reducing structure is a lifting pressure reducing structure provided in a structure into which water is installed, in which the lifting pressure reducing device according to any one of the above is installed, and the plurality of bag body portions are provided as follows: It is attached to the structure surface facing the water surface to penetrate.

  Here, the structure surface may be provided with a projecting portion projecting downward, and the bag body portion may be attached so as to surround the projecting portion.

  Further, the invention of the method for installing the lifting pressure reducing device includes a step of conveying the bag body portion to a position below the surface of the structure into which water enters while the bag body portion is folded, and an upper portion of the bag body portion via the attachment means. A step of attaching to the surface of the structure and a step of inflating the bag by injecting or injecting a gas from the hole are provided.

  The lift pressure reducing device of the present invention configured as described above includes a bag body portion filled with gas, and attachment means for attaching the bag body portion to a structure having a space into which water enters. .

  The lifting pressure due to tsunamis, storm surges, floods, etc. is buffered by the bag body just by attaching the lifting pressure reducing device with such a simple structure to the structure. Can be reduced.

It is sectional drawing explaining the structure of the lifting pressure reduction apparatus and lifting pressure reduction structure of this Embodiment. It is explanatory drawing which showed the structure of the lifting pressure reduction apparatus. It is a perspective view explaining the structure of a bag body part. It is explanatory drawing which showed the outline | summary of the experiment which confirms the effect of the lifting pressure reduction apparatus of Example 1. FIG. FIG. 6 is a diagram showing experimental results of a comparative example performed in Example 1. It is the figure which showed the experimental result of the lifting pressure reduction apparatus of this Embodiment performed in Example 1. FIG. It is a figure explaining the experimental result of Example 1 collectively. It is a figure explaining the validity of the experimental result of Example 1. It is sectional drawing explaining the structure of the lifting pressure reduction structure of Example 2. FIG. It is sectional drawing explaining the structure of the lifting pressure reduction structure of Example 3. FIG. It is a perspective view explaining the structure of the bag body part of Example 3. FIG. It is a perspective view explaining the structure of the bag body part of another form of Example 3. FIG. It is a side view explaining the structure of the lifting pressure reduction structure of Example 4. It is sectional drawing seen in the AA arrow direction of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view for explaining the configuration of the lifting pressure reducing device and lifting pressure reducing structure of the present embodiment.

  The lifting pressure reduction structure of this embodiment is a tsunami or storm surge wave or flow, such as a coastal facility such as a power plant or complex near the coast, a pier, or a structure near a river, or a wave or flow associated with a river flood. Is provided in a structure having a space for water to enter. The power plant has an intake and discharge channel 1 (intake channel and discharge channel) connected to seawater, and the slab of the pier is also a structure that is easily affected by rising water levels.

  In the present embodiment, a case where a lifting pressure reducing structure is provided in the intake / discharge channel 1 as shown in FIG. 1 will be described. This intake / discharge channel 1 is a structure that connects the sea and the piping 14 of the pump chamber 11.

  The lower surface 12 a of the water channel top end 12 of the pump chamber 11 is a structure surface facing the water surface W. That is, normally, the water surface W connected to the sea exists at a position spaced downward from the lower surface 12 a of the water channel top 12.

  The water surface W rises when a tsunami or storm surge occurs, and a shocking lifting pressure acts on the lower surface 12 a of the water channel top 12. And there exists a possibility that the top end lid 13 of the inspection port provided in the water channel top end 12 may be scattered by the action of impact lifting pressure.

  In addition, when the top end lid 13 is removed by impact lifting pressure, seawater flows into the facility through the inspection port, resulting in inundation damage. Furthermore, when the impact lifting pressure is large, the water channel top 12 may be damaged. In order to prevent the occurrence of such damage, a lifting pressure reducing device for reducing the impact lifting pressure is attached to the lower surface 12a.

  The lifting pressure reducing device according to the present embodiment includes a bag body portion 2 filled with gas, and a suspension portion 3 as an attachment means for attaching the bag body portion 2 to the lower surface 12a of the water channel top end 12. Configured.

  As shown in FIG. 2, the hanging part 3 includes, for example, a hook 31 fixed to the lower surface 12 a of the water channel top 12 and a hanging ring 32 as a hanging member joined to the upper surface 2 b of the bag body 2. Can be configured.

  On the other hand, the bag part 2 is formed in a rectangular parallelepiped shape, for example, as shown in FIG. The bag body 2 can be manufactured by forming a flexible sheet material such as cloth into a bag shape.

  The bag body 2 is formed of a material that hardly injects the gas injected into the inner space 22 even under pressure. For example, a woven fabric having a high tensile strength made of polyester fiber used as a material for a seat belt or the like can be used for the bag body portion 2. Moreover, since it will be installed in the position close | similar to the water surface W and contacted with water, the raw material which has functions, such as water repellency and waterproofness, can also be used.

  Furthermore, it is desirable that the bag body portion 2 is lightweight in order to suppress the load applied to the structure (water channel top end 12) to be attached as much as possible. For this reason, if the desired tensile strength can be obtained, a woven fabric made of nylon fibers used as a material for an automobile airbag or the like can also be used. Moreover, the bag part 2 can be formed also with a rubber material.

  In addition, the “bag portion 2 filled with gas” may be in a state where the gas is accumulated in the bag portion 2, and from the state where the bag portion 2 itself is pulled. , Refers to the state including the state in which gas is injected only to the extent that some soot remains.

  On the upper surface 2 b of the bag body 2, for example, suspension rings 32 for hooking the hook 31 at corner portions are provided. The bag body portion 2 does not need to be firmly fixed to the lower surface 12a of the water channel top end 12 and may be suspended to such an extent that it does not come off due to wind pressure or the like.

  On the other hand, the lower surface 2a of the bag body 2 is provided with a communication port 21 as a hole for communicating the inside and outside. The communication port 21 only needs to be formed in such a size that the gas in the inner space 22 does not escape at a stroke when the impact lifting pressure is applied.

  The gas filled in the inner space 22 of the bag body 2 is usually air. Since the inner space portion 22 and the water surface W side are in communication with each other through the communication port 21, if the injected gas is air in the pump chamber 11, it is not affected by the replacement of the gas.

  Next, a method for constructing a lifting pressure reducing device and a lifting pressure reducing structure according to the present embodiment and their operation will be described.

  First, the seawater flowing into the intake / discharge channel 1 is shielded so that the pump chamber 11 is in a dry state, and the hooks 31 are attached to predetermined positions on the lower surface 12 a of the channel top 12. On the other hand, the bag body 2 is in a folded state by removing the air in the inner space 22 from the communication port 21.

  And the bag part 2 of the folded state is conveyed to the lower space of the water channel top end 12 of the pump chamber 11, and the hook of the bag part 2 is attached to the hooks 31 attached to the lower surface 12a. 32,...

  In the state where the bag body portion 2 is attached to the lower surface 12a in this way, air is injected from the communication port 21 into the inner space portion 22 to inflate the bag body portion 2. If the size of the communication port 21 is small, this air injection can be performed using a device such as an air container. However, the air naturally flows in from the communication port 21 simply by expanding the bag body 2. You can also

  And the state where the lower surface 12a of the water channel top end 12 is covered with a plurality of bag body portions 2,... As shown in FIG. To.

  1 shows a state in which a plurality of bag bodies 2,... Are arranged in the depth direction (left and right direction on the paper surface) of the pump chamber 11, but the width of the water channel (direction perpendicular to the paper surface) is the bag body. If it is wider than the width | variety of the part 2, several bag body parts 2, ... will be attached also to the width direction of a water channel.

  The lift pressure reducing device of the present embodiment configured as described above is for attaching the bag body portion 2 filled with air to the lower surface 12a of the water channel top end 12 facing the water surface W. A suspension part 3 is provided.

  The main load added to the water channel top 12 which is an existing structure by installing this lifting pressure reducing device is the weight of the bag body portion 2,... There is no need to reinforce things.

  The lifting pressure reducing device having such a simple configuration can be easily attached to the lower surface 12a simply by hooking the suspension rings 32,...

  In particular, since the communication port 21 is provided in the bag body 2, the bag body 2 can be transported in a folded and easy-to-carry state, and can be easily inflated at a place where it is installed.

  Further, if the communication port 21 is provided on the lower surface 2a of the bag body portion 2, even if the bag body portion 2 is pushed up by the lifting pressure acting on the lower surface 2a, the air in the inner space portion 22 is communicated from the communication port 21. It will not come out.

  When seawater more than normal flows into the intake channel 1 due to a tsunami, storm surge, or the like, the water surface W that has risen on the bag body 2 or higher before the impact lifting pressure acts on the lower surface 12a. The applied air pressure is buffered by contact.

  For this reason, the lifting pressure which the water channel top 12 receives can be reduced. In particular, if a plurality of bag parts 2,... Are attached to the lower surface 12a, the lifting pressure received by the lower surface 12a can be reduced over a wide range.

  Next, an experiment conducted for confirming the effect of the lifting pressure reducing device described in the above embodiment and the result thereof will be described with reference to FIGS. Note that the description of the same or equivalent parts as those described in the above embodiment will be described with the same terms and the same reference numerals.

  The experiment was conducted in order to confirm the effect of reducing the lifting pressure by attaching the bag body 2 by simulating a shocking wave by a drop experiment. As shown in the cross-sectional view of FIG. 4, the impact when the plate-like weight part 4 (100 mm × 100 mm, 717 g, made of lead) with the bag part 2 attached to the lower surface is freely dropped toward the water surface W. The target pressure was measured. That is, the lower surface (surface on the bag body 2 side) of the weight portion 4 corresponds to the lower surface 12a of the water channel top end 12 described in the above embodiment.

  This bag part 2 is formed into a rectangular parallelepiped of 100 mm × 100 mm × 100 mm. For the bag body 2, a highly water-repellent fabric (an umbrella material “Water Barrier (registered trademark)” manufactured by Teijin Frontier Co., Ltd.) was used.

  In this bag body portion 2, a communication port 21 is formed in the lower surface 2 a, and the inner space portion 22 is filled with air. A pressure sensor 41 for measuring the impact pressure is attached to the lower surface side of the weight portion 4.

  This drop experiment was performed in a plurality of cases using the drop height h as a parameter. For comparison, a drop experiment of the weight 4A itself without the bag body 2 was also performed. Here, the fall height h is the distance from the lower surface 2a of the bag body portion 2 to the water surface W in the case where the bag body portion 2 is provided, and the water height W from the lower surface of the weight portion 4A in the case where the bag body portion 2 is not provided. It was set as the distance to.

  FIG. 5 shows an example of the measurement result of the weight part 4A having a drop height h = 2 cm and no bag body part.

  In the weight part 4A without the bag part, the time until the impact lifting pressure reached the peak was on the order of about 0.001 s. In short, the pressure starts to rise after 0.0025 s, and the pressure reaches a peak around 0.0035 s.

  On the other hand, FIG. 6 shows an example of the measurement result of the weight part 4 with the bag body part 2 at the drop height h = 2 cm. In the weight part 4 with the bag body part 2, the time until the impact lifting pressure reached the peak was on the order of about 0.01 s. In short, the pressure starts to increase after 0.01s, and the pressure reaches its peak before 0.03s.

  By attaching the bag part 2 in this way, the time until the impact lift pressure reached a peak could be extended ten times. Further, the peak of the impact lifting pressure is reduced to the order of 1/10 by attaching the bag part 2.

  Considering the impulse (force x action time) of the two experimental results, both are in the same order, so the validity of the experiment can be confirmed from this point. And by attaching the bag body part 2, it takes time until the bag body part 2 expands and generates a stress on the weight part 4 even if the lifting pressure starts to act, and the impact lifting pressure is reduced in inverse proportion to it. It was confirmed that there was an effect that the peak of the maximum pressure was 1/10.

  FIG. 7 shows the maximum pressure obtained in each experimental case in an organized manner. That is, it shows that the higher the drop height h, the higher the lifting pressure that acts by waves or the like. Three types of tests with h = 1, 2, and 5cm were conducted for “with bag”, but the impact pressure was about 2000Pa-3000Pa, and less than 1/3 of h = 1cm with “without bag” Met. The reason that the experimental result of “no bag part” is only up to h = 2 cm is that the maximum value of the pressure sensor 41 was reached at h = 5 cm, and the maximum pressure could not be measured.

  If the figure which compared this experimental result is seen, it is clear that the impact lift pressure which acts can be reduced significantly by attaching the bag part 2. FIG. On the other hand, in FIG. 8, the result of the hydraulic model experiment performed so far with respect to the modeled intake / discharge channel 1 is also illustrated.

  The comparative hydraulic model experiment was an assumed model scale 1/30, model length 460cm, square section with a side of 15cm, two vertical shafts (opening 10cm x 15cm), top of waterway (pressure gauge mounting position) The height of up to 25cm from the bottom of the canal was used. The experiment was carried out by changing the wave pattern (tsunami height 3m-22m in actual scale) by generating a tsunami with a chamber-type tsunami wave generator with a water depth of 17cm in this intake model. The results obtained from the experiment were calculated using three approximate curves (impact pressure 1 (minimum value), impact pressure 2 (average value), impact pressure 3 (maximum value). )).

  The result of this past experiment case (impact pressure 1-3) corresponds to the result of “no bag body part”, and the result of the experiment of “no bag body part” performed this time shows almost the same tendency. A tendency close to pressure 1 is shown. In other words, it was confirmed that the experimental result of “without bag” due to free fall was similar to the result of the hydraulic model experiment conducted separately. As applicable.

  Other configurations and operational effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Next, another embodiment different from the lifting pressure reducing structure described in the above embodiment will be described with reference to FIG. Note that the description of the same or equivalent parts as those described in the embodiment or Example 1 will be given with the same terms and the same reference numerals.

  The lifting pressure reducing structure described in the second embodiment is provided in a building 5 such as a building, a condominium, or a warehouse built near the coast. The building 5 is provided with an opening 51 such as an elevator hall, a staircase hall, a garage, a store, and a storage space on the ground floor.

  If a tsunami, storm surge, or the like occurs, there is a risk that upstream seawater will flow into the open portion 51. And if the water surface W of the seawater which went up goes up, the (impact) lifting pressure will act on the ceiling surface 52 used as the structure surface of the open part 51. FIG.

  On the other hand, the ceiling surface 52 may be covered with a decorative board 53. The decorative board 53 is suspended from the ceiling surface 52 by suspension materials 54,..., And the operation of attaching the bag body 2 to the ceiling surface 52 is performed in a narrow space.

  Even in such a narrow space, the folded bag part 2 can be easily carried. Moreover, if it is the operation | work which fixes the hooks 31 ... to the ceiling surface 52, since a large-scale apparatus and tool are not required, it can implement also in a narrow space.

  Furthermore, the folded bag part 2 can be easily inflated even in a narrow space between the ceiling surface 52 and the decorative plate 53 by injecting air from the communication port 21.

  In addition, even after the plurality of bag body portions 2,... Are attached to the ceiling surface 52, if they are between the bag body portions 2, 2 that are simply filled with a flexible material, they are scraped. Since it can easily pass through, it is excellent in workability.

  Furthermore, the bag part 2 once suspended can be easily removed as needed. Moreover, since the air of the inner space part 22 can be extracted and folded from the communication port 21 of the bag body part 2, even if it is placed in a narrow space, it does not get in the way and a work space can be secured.

  Other configurations and operational effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Next, another embodiment different from the lifting pressure reducing device described in the above embodiment will be described with reference to FIGS. In addition, about the description of the part same or equivalent to the content demonstrated in the said embodiment or Example 1, 2, it attaches | subjects and demonstrates the same term and the same code | symbol.

  In the above embodiment and Examples 1 and 2, the description has been made on the assumption that the impact lift pressure mainly acts in the vertical direction from the bottom to the top. On the other hand, as shown in FIG. 10, the wave pressure from the side may act in advance.

  If the bag body portion 6 is reduced by the wave pressure from the side, it may not be able to effectively act on the lifting pressure. In the third embodiment, a configuration of the bag body portions 6 and 7 for avoiding such a situation will be described.

  First, the bag part 6 shown in FIG. 11 has an inner space sectioned into four spaces by partition walls 62. And in order to make each compartment fill with gas, the lower surface 6a is respectively perforated with communication ports 61,... As holes for communicating the inside and outside of each compartment.

  Thus, if each section is completely partitioned, only the section contracts even if wave pressure acts from the side, and the expanded state of other sections can be maintained. Moreover, it can also be set as the structure of the bag part 7 as shown in FIG.

  As with the bag body portion 6, the bag body portion 7 is divided into four spaces by partition walls 72,. However, the communication port 71 as a hole drilled in the lower surface 7a for injecting gas is provided only for one section.

  And the section provided with the communication port 71 and the other sections are connected to each other by communication holes 73,. For this reason, the air injected from the communication port 71 can be filled in each section.

  On the other hand, when the wave pressure is applied from the side, air is discharged from the communication port 71 after moving sideways through the communication hole 73 on the partition side where the communication port 71 is not provided. The shrinkage of the compartment can be suppressed or delayed.

  By using the bag body portions 6 and 7 having such a configuration, even if the bag body portions 6 and 7 are installed in a place where the wave pressure is received from the side, the shrinkage is suppressed and effective against the lifting pressure. The reduction function can be exhibited.

  Other configurations and operational effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  Next, another embodiment different from the lifting pressure reducing device and lifting pressure reducing structure described in the above embodiment will be described with reference to FIGS. In addition, about the description of the part same or equivalent to the content demonstrated in the said embodiment or Example 1-3, the same term and the same code | symbol are attached | subjected and demonstrated.

  In the fourth embodiment, a lifting pressure reducing structure that surrounds a protruding portion that protrudes downward from the structure surface will be described. For example, as described in the above embodiment, the pump chamber 11 is provided with the pipe 14 protruding downward from the lower surface 12a of the water channel top 12.

  The pipe 14, which is a columnar projection, is attached through the water channel top end 12. When the lower surface 12 a is subjected to impact lifting pressure due to a tsunami or the like, the water channel top end 12 extends from the periphery of the pipe 14. There is a possibility that water may spout upward or the pipe 14 may be damaged.

  Therefore, the lifting pressure reducing device protects the cylindrical pipe 14 so as to surround the annular pipe 14 in an annular shape. For this reason, the bag part 8 which comprises the lifting pressure reduction apparatus of the present Example 4 is formed in the circular arc board shape which divided | segmented the cylinder into plurality.

  Here, the number of divisions of the cylinder can be arbitrarily set. In the fourth embodiment, as shown in FIG. 14, a case where the ring is divided into four parts in plan view will be described. A suspension ring 32 to be the hanging portion 3 is attached to the upper surface 8b of the bag body portion 8, and a communication port 81 as a hole for communicating the inside and the outside is drilled in the lower surface 8a.

  Further, connection portions 82 such as hook-and-loop fasteners are provided on the side end surfaces 8c and 8c in the circumferential direction. That is, the arcuate plate-like bag body portion 8 can be suspended by the suspension portion 3 along the outer periphery of the pipe 14 to take in air from the communication port 81 and fill it. ... cannot be made to behave integrally with impact lifting pressure.

  Therefore, the bag parts 8 and 8 which are adjacent to each other in the circumferential direction are connected to each other through the connection part 82, and the pipe 14 is formed by a lifting pressure reducing structure including the bag parts 8 formed in a cylindrical shape. The outer periphery is surrounded.

  Thus, even if there is a projecting portion such as a pipe 14 projecting downward from the lower surface 12a of the water channel top end 12 facing the water surface W, the bag body portion 8 adapted to the shape thereof,...・ Attachment can reduce the impact lifting pressure.

  Other configurations and operational effects are substantially the same as those of the above-described embodiment or other examples, and thus description thereof is omitted.

  The embodiments and examples of the present invention have been described in detail above with reference to the drawings. However, the specific configuration is not limited to the embodiments and examples, and the gist of the present invention is not deviated. Design changes are included in the present invention.

  For example, in the embodiments and examples described above, the rectangular parallelepiped bag portions 2, 6, and 7 have been described. However, the present invention is not limited to this, and various forms such as a cylindrical shape, a spherical shape, and an elliptical spherical shape are possible. It can be formed into a bag body.

  Moreover, in the said embodiment, although the structure by the hook 31 and the suspension ring 32 was demonstrated to the example as an attachment means and the suspension part 3, it is not limited to this, The attachment means of various forms is applied. can do. For example, a drill screw for directly joining an edge portion not communicating with the inner space of the bag body portion to the lower surface 12a can be used as the attachment means.

  Furthermore, in the said embodiment and Example, although the case where the communication ports 21, 61, 71, 81 were provided in the lower surfaces 2a, 6a, 7a, 8a of the bag body portions 2, 6, 7, 8 was described, It is not limited, The hole which makes the inside and outside communicate with one side or several surfaces, such as a side surface, an upper surface, and a lower surface of a bag body part, can also be provided.

  Moreover, in the said embodiment or Example 2, although the structure which installs the bag body parts 2 ... so that the lower surface 12a of the water channel top end 12 or the substantially whole surface of the ceiling surface 52 was covered was demonstrated, it is limited to this. However, it is also possible to provide a lifting pressure reducing structure in which the bag body part 2 is partially attached only to a location where the lifting pressure is likely to act or a location where the lifting pressure tends to be weak.

  Furthermore, in the said embodiment and Example, although the case where seawater infiltrated was mainly demonstrated, it is not limited to this, When lift pressure acts by the wave and flow accompanying a flood of a river Can also exert a reduction effect.

12a Bottom surface (structure surface)
14 Piping (protruding part)
2 Bag body part 2a Lower surface 2b Upper surface 21 Communication port (hole)
3 Hanging part (mounting means)
32 Suspension ring (suspending member)
52 Ceiling (structure surface)
6, 7, 8 Bag body portion 6a, 7a, 8a Lower surface 61, 71, 81 Communication port (hole)
W Water surface

Claims (5)

A lifting pressure reducing device for a structure having a space into which water enters,
A bag portion filled with gas;
An attachment means for attaching the bag body portion to the structure ,
In the bag body portion, a hole communicating with the inside and outside of the bag body portion is provided only on the lower surface,
A lifting pressure reducing device, wherein a suspension member constituting the attachment means is provided on an upper surface of the bag body . The lifting pressure reducing device according to claim 1, wherein an inner space of the bag body portion is divided into a plurality of sections. Claim 1 or a uplift reducing structure provided in the lifting structure pressure reduction device is installed the water enters according to 2,
A lifting pressure reducing structure, wherein the plurality of bag parts are attached to a structure surface facing a water surface to be infiltrated. 4. The lift according to claim 3 , wherein the structure surface is provided with a projecting portion projecting downward, and the bag body portion is attached to surround the projecting portion. Pressure reduction structure. It is the installation method of the lifting pressure reduction apparatus of Claim 1 , Comprising:
A step of transporting to the lower side of the structure surface into which water enters in a state in which the bag body portion is folded;
Attaching the upper portion of the bag body portion to the structure surface via the attachment means;
And a step of inflating the bag by injecting or injecting gas from the hole.