JP3204471U - Water flow attenuating network and wave protection device using the same - Google Patents

Abstract

A water flow attenuating network capable of effectively attenuating a water flow of a tsunami without being easily destroyed by the water pressure of the tsunami regardless of the scale of the tsunami, and a wave preventing device using the same. When a sea surface rises due to a tsunami, one end side of a net body 2 sinks due to the tension of a connecting member 6 connected to an anchor member 5 and the buoyancy of a first floating body 3 generated on the other end side of the net body 2 is settled. Since the net body 2 stands up in the sea with the other end side up, a flow resistance is given to a part of the water flow passing through the net body 2 and other water flow that does not pass through the net body 2 is added to the net. Guided to the side of the body 2, the tsunami water flow is attenuated. One end side of the mesh body 2 is connected to the connecting member 6, but the other end side of the mesh body 2 is not connected to the seabed side, so excessive water pressure is applied to the mesh body 2 even in a large-scale tsunami. There is no participation. [Selection] Figure 3

Description

  The present invention relates to a water current attenuating network that is installed off the coast and reduces the height and momentum of a tsunami and a wavebreaker using the same.

  In recent years, large-scale disasters due to tsunamis have occurred in coastal areas, and as measures to prevent tsunami disasters, breakwaters, seawalls, embankments and the like made of concrete structures have been installed. However, such a fixed structure has a limit in strength and height to prevent a tsunami. That is, for a large-scale tsunami that exceeds the expected height, the effect of preventing the tsunami is insufficient, such as insufficient height to catch the tsunami or destruction by excessive water pressure of the tsunami. For this reason, damage such as evacuees who have escaped to high altitudes is expected to fall into the tsunami.

  As the tsunami approaches the coast from the offshore, the density of kinetic energy increases as the water depth becomes shallower, and water pressure is concentrated on the breakwaters and embankments. If it can be attenuated, the height and power of the tsunami that reaches the coast can be reduced.

  Therefore, conventionally, there has been proposed a technique aimed at reducing the energy of the tsunami before reaching the coast by slowing down the tsunami water flow with a net extended offshore (see, for example, Patent Document 1). .)

  In this conventional example, one end of the net is connected to an anchor member on the seabed, and the other end of the net is connected to an anchor member at another position on the seabed via a rope. In addition, when a tsunami occurs and the water flow increases, the net expands in the water, and the flow velocity of the water flow is reduced by the flow resistance when the tsunami passes through the net.

JP 2008-63826 A

  In the conventional example, one end side and the other end side of the net are connected to the sea bottom side, and the tsunami water pressure is applied in such a way that the sail of the ship receives the wind, so the stress generated on the net and rope depends on the water pressure. Become bigger. However, because tsunami is a natural phenomenon, it is difficult to predict its scale and power, and when excessive water pressure is applied by a large tsunami, the net or lobe breaks or the anchor member comes off the seabed. There was a risk of being destroyed by the tsunami.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to easily attenuate the water flow of the tsunami without being easily destroyed by the water pressure of the tsunami regardless of the scale of the tsunami. It is an object of the present invention to provide a water flow attenuating network and a wave preventing device using the same.

  In order to achieve the above-mentioned object, the water flow attenuating net of the present invention includes a net for receiving a water flow caused by a tsunami, a floating body for imparting buoyancy to the net, an anchor member disposed on the seabed, and one end of the net. A connecting member for connecting the side and the anchor member. When the sea level rises due to a tsunami, the entire mesh body is floated on the sea surface by a floating body, and the tension of the connecting member connected to the anchor member The one end side sinks, and the net body stands up in the sea with the other end side up by the buoyancy of the floating body.

  As a result, when the sea level rises due to the arrival of a tsunami, one end side of the net body sinks due to the tension of the connecting member connected to the anchor member, and the net body rises in the sea with the other end side facing up. The flow velocity is reduced by the flow resistance when a part of the water flow straight in the direction passes through the mesh of the mesh body, and other water flows that are blocked from passing by the mesh flow resistance are lateral to the network body. As a result, the momentum of the water flow downstream of the water flow attenuation network is attenuated. In this case, one end of the net is connected to the connecting member, but the other end of the net is a free end that is not connected to the seabed. Excessive water pressure is not applied to the net as is the case when connected to the seabed.

  In order to achieve the above object, the wave breaker of the present invention includes a plurality of the water flow attenuation networks, and each water flow attenuation network is arranged in a plurality of rows with respect to the traveling direction of the tsunami.

  As a result, since the plurality of water attenuation networks are arranged in a plurality of rows in the traveling direction of the tsunami, the tsunami momentum is attenuated in multiple stages by the water attenuation networks in each row.

  According to the present invention, it is possible to give flow resistance to a part of the water flow that passes through the mesh body, and to guide the other water flow that does not pass through the mesh body to the side of the network body. Can be attenuated and the height and power of the tsunami reaching the coast can be reduced. In this case, since an excessive water pressure is not applied to the net body even in a large-scale tsunami, there is an advantage that it is not easily destroyed by the tsunami.

The side view which shows one Embodiment of the water flow attenuation net | network of this invention Top view of water flow damping network Side view showing operation of water attenuation network Plan view showing operation of water flow damping network The top view which shows 1st Embodiment of the wave protection device of this port proposal Partial plan view showing the operation of the wave breaker Plan view of water attenuation network in second embodiment of wave protection device of this port plan Plan view showing operation of water flow damping network Partial plan view showing the operation of the wave breaker Plan view showing installation example of wave breaker Plan view showing the operation of the wave breaker

  1 to 4 show an embodiment of the present invention, and show a water flow attenuation network for attenuating a tsunami water flow.

  A water flow attenuating network 1 shown in FIG. 1 includes a net body 2 for receiving a water flow caused by a tsunami, first and second floating bodies 3 and 4 for imparting buoyancy to the net body 2, and a pair of anchors disposed on the seabed. A member 5 and a pair of connecting members 6 that connect one end side of the mesh body 2 and each anchor member 5 are provided.

  The net body 2 is made of a synthetic resin net having a high tensile strength, and is formed, for example, in a quadrangular shape having a side of 100 m. The mesh size of the mesh body 2 is preferably about 100 mm × 100 mm at the minimum and about 300 mm × 300 mm at the maximum. In addition, a seaweed cultivation net that allows seaweeds to easily reproduce is used for the net body 2. Examples of such a seaweed cultivation net are described in JP-A Nos. 2003-158929 and 2006-180721, for example. is there.

  The first and second floating bodies 3, 4 are made of a spherical member formed in a hollow shape, and are attached to the periphery of the net body 2 at intervals from each other. The first floating body 3 is formed larger than the second floating body 4, the first floating body 3 is disposed on one side of the four sides of the net body 2, and the second floating body 3 is disposed on the other three sides of the net body 2. A floating body 4 is arranged.

  Each anchor member 5 consists of a heavy material made from concrete, and is arrange | positioned at intervals at the seabed. The shape of the anchor member 5 is preferably a starfish shape as in the present embodiment, for example, as a shape that is difficult to fall over and difficult to be dragged, but may be other shapes such as a low-profile columnar shape or a prismatic shape.

  Each connecting member 6 is made of a synthetic resin rope having high tensile strength, and one end thereof is connected to each anchor member 5. The other end of each connecting member 6 is connected to both ends of one end side of the mesh body 2 (the other side opposite to one side of the mesh body 2 on which the first floating body 3 is disposed). In this case, each connecting member 6 is formed to be slightly longer than the distance from the sea level position S at normal times (at high tide) to the anchor member 5 on the seabed.

  The water flow attenuating network 1 configured as described above is installed offshore in the coastal region. In this case, in the water flow attenuating network 1, the anchor members 5 are arranged in the direction orthogonal to the traveling direction of the tsunami with an interval substantially equal to the width of the network 2 and one end side of the network 2 is It arrange | positions so that the other end side of the upstream and the net body 2 may become the downstream of a tsunami.

  Next, the operation of the water flow attenuation network 1 will be described. First, as shown in FIG. 1, the entire net body 2 is floating on the sea surface due to the buoyancy of the first and second floating bodies 3 and 4 in a normal state. In this case, since the 1st and 2nd floating bodies 3 and 4 are arrange | positioned at the periphery of the net body 2, as shown in FIG. 2, the net body 2 is maintained in the state extended along the sea surface.

  Here, when a tsunami occurs offshore and the sea level rises from the sea level position S due to the arrival of the tsunami as shown in FIG. 3, the mesh body is caused by the tension of each connecting member 6 connected to each anchor member 5. The one end side of 2 sinks, and the net body 2 rises in the sea with the other end side up. At that time, in the water flow attenuating network 1, as shown in FIGS. 3 and 4, the network body 2 bends to the tsunami traveling method due to the water pressure of the tsunami and goes straight in the tsunami traveling direction as shown by the white arrow in the figure. The flow velocity is reduced by the flow resistance when a part of the flowing water flows through the mesh of the mesh body 2, and other water flows blocked by the flow resistance of the mesh body 2 are left and right of the network body 2. By being guided to both sides, the momentum of the water flow downstream of the water flow attenuating network 1 is attenuated. In this case, one end side of the mesh body 2 is connected to the connecting member 6, but the other end side of the mesh body 2 is a free end that is not connected to the seabed side. The tsunami pressure can be released without applying excessive water pressure to the net body 2 as in the case where both sides are connected to the seabed side.

  In normal times, seaweeds will reproduce in the net 2 floating on the surface of the sea. Around the net 2 are fish that eat seaweeds and other fish that supplement the fish. It reproduces and the net 2 serves as a fish reef. As a result, the surroundings of the water flow attenuating net 1 become abundant fishing grounds, and it is possible to contribute to fishing and aquaculture in the surrounding sea area.

  Thus, according to the water flow attenuation network of the present embodiment, when the sea level rises due to a tsunami, one end side of the mesh body 2 sinks due to the tension of the connecting member 6 connected to the anchor member 5, and Because the buoyancy of the first floating body 3 generated at the end side causes the net body 2 to stand up in the sea with the other end side up, a flow resistance is given to a part of the water flow passing through the net body 2 and the net Other water streams that do not pass through the body 2 can be guided to the side of the mesh body 2. As a result, the water flow of the tsunami can be effectively attenuated, and the height and power of the tsunami reaching the coast can be reduced.

  In this case, one end side of the mesh body 2 is connected to the connecting member 6, but the other end side of the mesh body 2 is not connected to the seabed side, so even a large-scale tsunami is excessive to the mesh body 2. There is an advantage that the water pressure is not applied and is not easily destroyed by the tsunami.

  In addition, since the net body 2 is floating on the sea surface during normal times, the presence of the net body 2 can be easily confirmed from the sea, and the fishing net of the fishing boat is caught on the net body 2. A trouble can be avoided. Furthermore, since the net body 2 does not sink to the seabed in normal times, there is an advantage that it does not affect the ecosystem of marine organisms living near the seabed.

  In addition, since the entire net 2 is floated on the sea surface by the first and second floating bodies 3 and 4 in normal times, the net 2 can reproduce seaweeds, It is also possible to make the surroundings abundant fishing grounds. As a result, it can contribute to the fishery and aquaculture industry in the surrounding sea area, and there is an advantage that unnecessary tsunami countermeasures can be effectively used in normal times.

  Furthermore, since the net body 2 is formed in a quadrangular shape and the connecting members 6 are connected to both ends of one side of the net body 2, the net body 2 can be greatly expanded when receiving a tsunami water flow, The water flow attenuation effect can be enhanced.

  In addition, since the first and second floating bodies 3 and 4 are arranged at the periphery of the net body 2, the net body 2 floating on the sea surface can be kept extended along the sea surface. It is extremely advantageous for seaweed reproduction.

  In this case, the first floating body 3 arranged on the other end side of the net body 2 is formed so as to have a buoyancy larger than that of the second floating body 4 arranged on one end side of the net body 2. This makes it easier to stand up in the sea with the other end facing up, and can further enhance the tsunami current attenuation effect.

  5 and 6 show a first embodiment of a wave breaker using a plurality of the water flow attenuating networks 1.

  As shown in FIG. 5, the wave protection device 10 shown in FIG. 5 has a plurality of water flow attenuating networks 1 installed in a plurality of rows in the traveling direction of the tsunami. In this case, the water flow attenuating networks 1 are arranged downstream of the water flow attenuating networks 1 in the front row (upstream on the tsunami traveling direction) and on the downstream side (rows on the downstream side in the tsunami traveling direction). It is arranged in a staggered pattern so as to be located. Further, each water flow attenuating network 1 is arranged in a fan shape as a whole so that the number of water flow attenuating networks 1 in each row gradually increases from the upstream side to the downstream side in the tsunami traveling direction.

  In this wave breaker 10, since the plurality of water attenuation networks 1 are installed in a plurality of rows with respect to the traveling direction of the tsunami, the tsunami momentum is generated in multiple stages by the water attenuation networks 1 in each row. Attenuated. In this case, since the water flow attenuating networks 1 are arranged in a staggered manner, the water flow of the tsunami does not pass between the water flow attenuating networks 1 in each row, and the water flow attenuating network 1 in the front row as shown in FIG. The water flow induced to the side of the network body 2 flows into almost the front surface of the network body 2 of the rear stream water flow attenuation network 1, and the water flow attenuation network 1 of each line can effectively attenuate the tsunami water flow.

  7 to 9 show a second embodiment of a wave breaker using a plurality of the water flow attenuation networks 1.

  In the wave breaker 10 of the first embodiment, the tsunami water flow is uniformly guided to the left and right sides of the net body 2. However, in the wave breaker 20 of the present embodiment, the tsunami water flow When received, the net 2 rises in the sea so that it tilts to the left or right with respect to the traveling direction of the tsunami, and the water flow of the tsunami is guided to one side of the net 2.

  That is, in this embodiment, as shown in FIG. 7, one connecting member 6 (left side in the figure) of the pair of left and right connecting members 6 is longer than the other connecting member 6 (right side in the figure). When each connecting member 6 is strained in response to a tsunami current, the net 2 is inclined by the length of one connecting member 6 longer than the other connecting member 6, as shown in FIG. Thus, the water flow of the tsunami is guided to one side of the net 2.

  Note that, similarly to the wave preventing device 10 of the first embodiment, the wave attenuating device 20 of the present embodiment is such that each water flow attenuating network 1 is positioned between the water attenuating network 1 in the front row and the water attenuating network 1 in the rear row. Are arranged in a zigzag pattern, and are arranged in a fan shape as a whole so that the number of water flow attenuating networks 1 in each row gradually increases from the upstream side to the downstream side in the tsunami traveling direction.

  In the wavebreaker 20 of the present embodiment, as in the first embodiment, the tsunami momentum is attenuated in multiple stages by the water flow attenuation network 1 of each row. In this case, since the mesh body 2 is inclined to the left or right with respect to the traveling direction of the tsunami, the water flow of the tsunami is caused by the water flow attenuation network 1 of each row as shown by the white arrow in FIG. 2 guided to one side. Thereby, since the traveling direction of the tsunami can be changed to the left or right in the entire wave preventing device 20, for example, even if a tsunami arrives, the tsunami can be induced in a direction with less damage.

  FIG. 10 and FIG. 11 show an example in which the wavebreaker is installed offshore in the coastal area, and is an example of installation in the case of terrain with hills B on both sides of the coast A where there are houses and ports on the land side. .

  In this installation example, the first wave-breaking device group G1 including a plurality of wave-breaking devices that guide the water flow of the tsunami equally to the left and right is installed in the center, and the water flow of the tsunami is on the left and right sides (left side in the figure). A second wavebreaker group G2 composed of a plurality of wavebreakers to be guided is installed on the left side in the drawing, and a third wavebreaker consisting of a plurality of wave breakers for guiding the tsunami water flow to the left and right sides (right side in the figure). Is installed on the right side of the figure. In this case, each of the wave breakers in the first wave breaker group G1 includes the same first wave breaker 10 as in the first embodiment (the water flow attenuating network 1 induces the water flow of the tsunami equally to the left and right. ) Is used, and each of the wave breakers in the second wave breaker group G2 has a second wave breaker 20 similar to that of the second embodiment (the water flow attenuating network 1 transmits the water flow of the tsunami to the left and right sides). (The one that leads to the left side in the figure) is used. Further, each of the wave breakers of the third wave breaker group G3 includes a third wave breaker 30 (the water flow attenuating network 1 formed by the second wave breaker 20 in the opposite direction). The one that guides to the left and right other side (right side in the figure) is used.

  In this installation example, as indicated by the white arrow in FIG. 11, when the tsunami arrives off the coast, the tsunami passing through the second wave-breaking device group G2 changes its direction to the left and right and changes to the left hill. The tsunami that travels toward B and passes through the third wavebreaker group G3 changes direction to the left and right and proceeds toward the right hill B. Moreover, the tsunami that passes through the first wavebreaker group G1 travels straight with the water current attenuated.

  As described above, in the installation example, the tsunami traveling toward the coast A is guided to the left and right hills B by the second and third wavebreaker groups G2 and G3, and the water flow of the straight traveling tsunami is the first. Because the tsunami guided to the left and right is prevented from going up to the land by the plateau B, and the tsunami arriving at the central coast A where the height from the sea level is low You can reduce the height and power. Thereby, the damage of the tsunami on the land side in the terrain as in the installation example can be reduced.

  In addition, the said installation example is an example and can be set as another installation form according to the topography of a coastal part. That is, the first wave breaker 10 has a high attenuation effect on the tsunami water flow, and the second and third wave breakers 20 and 30 have a high effect on changing the traveling direction of the tsunami. In the topography where the width of the coastal part where the height of the coast is low is narrow, by installing the second or second wave breaker 20 or the third wave breaker 30, the tsunami is guided to one side to reach the inlet. If the approach of tsunami is prevented, it is thought that the wave prevention effect on such topography can be enhanced. Also, for example, on a coastline where the beach continues for a long time, if the tsunami water flow is attenuated by installing the first wave breakers 10 in multiple rows along the coastline, it is possible to prevent such terrain. It is thought that the wave effect can be enhanced.

  DESCRIPTION OF SYMBOLS 1 ... Water flow attenuation | damping network, 2 ... Net body, 3 ... 1st floating body, 4 ... 2nd floating body, 5 ... Anchor member, 6 ... Connection member, 10 ... 1st wave preventing device, 20 ... 2nd prevention Wave device, 30... Third wave protection device.

Claims (8)

A net to receive water flow from the tsunami,
A floating body that imparts buoyancy to the net;
An anchor member disposed on the seabed;
A connecting member for connecting the one end side of the net body and the anchor member;
Under normal conditions, the entire mesh body is floated on the sea surface by a floating body, and when the sea surface rises due to a tsunami, one end side of the mesh body sinks due to the tension of the connecting member connected to the anchor member, and the mesh body is moved away by the buoyancy of the floating body. A water-damping network characterized by standing up in the sea with its end facing up. The water flow attenuating net according to claim 1, wherein the net body is formed in a quadrangular shape, and the connecting members are connected to both ends of one side of the net body. The water flow attenuating net according to claim 1 or 2, wherein the floating body is arranged at a periphery of the net. The water flow attenuating net according to claim 3, wherein the floating body disposed on the other end side of the net body is formed to have a greater buoyancy than the floating body disposed on the one end side of the net body. A plurality of water flow attenuating networks according to claim 1, 2, 3 or 4,
A wave breaker characterized in that each water flow attenuating network is arranged in multiple rows with respect to the tsunami traveling direction. The wave preventing device according to claim 5, wherein each of the water flow attenuating nets is formed so that the net body is inclined to one side with respect to a traveling direction of the tsunami in a state where the water flow of the tsunami is received. Each of the water flow attenuating networks is arranged so that the water flow attenuating network in the downstream row in the tsunami traveling direction is located downstream of the water attenuating network in the upstream row in the tsunami traveling direction. The wave preventing device according to claim 5 or 6. The water flow attenuating networks are arranged so that the number of water attenuating networks in each row gradually increases from the upstream side to the downstream side in the tsunami traveling direction. Wave protection device.

Images