JPH1181515A - Sound absorbing member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high durability by using a synthetic fiber nonwoven fabric block as a sound absorbing member, and combining the synthetic fiber nonwoven fabric block with a polyvinylidene chloride fiber and a bridge agent of synthetic resin material having weatherability. SOLUTION: A sound absorbing member 1 is molded from a surface plate 11 having a large number of openings such as aluminium, expand metal, punching metal, louver, etc., and a sound absorbing material 12 of a synthetic fiber nonwoven fabric block. The synthetic fiber nonwoven fabric block is molded by melting and welding polyvinylidene chloride fiber having high chemical material efficiency resistance and a bridge agent having melting point lower than polyvinylidene chloride fiber such as polyester fiber, etc., having weatherability. Then, the polyvinylidene chloride fiber is 10-100 denier, the bridge agent of the polyester fiber, etc., is 1-10 denier, the polyvinylidene chloride fiber is 98-60 wt.% and the polyester fiber is 2-40 wt.%. Accordingly, a color harmonized with the circumferential environment can be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound-absorbing device provided below a sound-insulating wall, a viaduct of an elevated viaduct, an elevated railway or the like (in this specification, sometimes referred to simply as "viaduct"). And a sound absorbing member used in a fall prevention device.

[0002]

2. Description of the Related Art With an increase in traffic volume and an increase in the size of vehicles, measures against traffic noise have been strongly demanded. To cope with this, soundproof walls provided with various soundproof members have been put into practical use. FIG. 10 shows a cross-sectional structure of a soundproof wall most commonly used at present. The soundproof wall includes a surface plate 111 made of a metal plate material having a louver structure subjected to rust prevention processing, a sound absorbing material 112 made of glass wool whose surface is covered with a synthetic resin film 112a, and a space 115 on the back of the sound absorbing member 112.
A unit block 10 composed of a back plate 114 made of a rust-proof metal plate and a frame member 113 made of a rust-proof metal plate that seals a space 115.
The unit block 101 is inserted into and fixed to a post made of H-shaped steel or the like that has been subjected to rustproofing, or is fixed directly to a concrete side wall to form a soundproof wall.

[0003]

By the way, the soundproof wall is
The vehicle is exposed to extremely poor environments such as exhaust gas emitted by the vehicle, vibrations from the vehicle, rainwater, etc., and in some cases, is washed by a washing vehicle equipped with brushes and high-pressure water nozzles. Required. Also, in order to harmonize with the surrounding environment, it is necessary to consider the soundproof wall in terms of colors and the like. However, as shown in FIG. 10, the conventional soundproofing member used for the soundproofing wall is such that a sound absorbing material 112 made of glass wool whose surface is covered with a synthetic resin film 112a is arranged so as to directly contact the back surface of the surface plate 111. The synthetic resin film 112a
However, it deteriorates due to long-term use, and is damaged by the vibration of the traveling vehicle or a large load acting during cleaning, and if left unattended for a long period of time, glass wool will scatter, causing environmental destruction and eventually pollution. Had the problem that

Also, a sound absorbing material 112 made of glass wool.
Because it is difficult to color, when using a metal plate material with many openings such as expanded metal or punched metal on the surface plate, color these openings in harmony with the surrounding environment Was difficult.

The present invention solves the above-mentioned problems of the sound absorbing member used for the conventional soundproof wall, has high durability,
It is an object of the present invention to provide a sound-absorbing member capable of giving a color in harmony with the surrounding environment without destroying the surrounding environment.

[0006]

To achieve the above object, the sound absorbing member of the present invention is characterized in that a synthetic fiber nonwoven fabric block is used as a sound absorbing material.

This sound absorbing member uses a synthetic fiber non-woven fabric block as a sound absorbing material. Therefore, unlike a conventional sound absorbing material made of glass wool, glass wool does not scatter and cause environmental destruction. Can be colored.

In this case, the synthetic fiber non-woven fabric block is entangled with polyvinylidene chloride fiber,
The polyvinylidene chloride fiber can be formed by bonding with a bridging agent made of a synthetic resin material having weather resistance.

Thus, a sound absorbing material having high water resistance against rainwater and the like and chemical resistance against exhaust gas and the like can be obtained, and the durability of the sound absorbing member can be improved.

Further, a fiber having a lower melting point than polyvinylidene chloride fiber such as polyester fiber can be used as the bridging agent. In this case, the polyvinylidene chloride fiber has a density of 10 to 100 denier, and the fiber having a lower melting point than the polyvinylidene chloride fiber such as polyester fiber used for the bridging agent has a thickness of 1 to 10 denier. In addition, both use polyvinylidene chloride fiber at a ratio of 98 to 60% by weight and low melting point fiber at a lower ratio of 2 to 40% by weight. It is preferable that the polyvinylidene chloride fibers are bonded by melting.

[0011] Thus, together with the polyvinylidene chloride fiber, the fiber having a lower melting point than the polyester fiber such as polyester fiber is entangled, and the whole is heated to melt the low melting point fiber. It is possible to obtain a synthetic fiber nonwoven fabric block that can be bonded, is homogeneous, and hardly loses its shape.

Further, the sound absorbing material can be constituted by combining a plurality of synthetic fiber nonwoven fabric blocks having different densities. In this case, the synthetic fiber non-woven fabric block is laminated in the noise incident direction, and the synthetic fiber non-woven fabric block of the sound absorbing material located on the noise incident side has a lower density than the synthetic fiber non-woven fabric block on the back side. It is preferred to use blocks.

This makes it possible to efficiently reduce noise in a wide range of frequencies. In particular, the sound absorbing material synthetic fiber nonwoven fabric block located on the noise incident side has a lower density than the synthetic fiber nonwoven fabric block on the back side. By using the synthetic fiber nonwoven fabric block, it is possible to obtain the effect of reducing noise in a wide range of frequencies while increasing the incidence rate of noise.

The sound-absorbing member of the present invention can be used for a sound-absorbing device or a fall-preventing device provided below a viaduct floor slab, which the present inventors have previously proposed. In the former case, The front plate is formed in a shape having a bulging portion protruding outward, and a back plate serving also as a scaffold plate having a large number of openings is arranged on the back of the sound absorbing material, and in the latter case, The front plate is formed in a shape having a bulging portion protruding outward, and a back plate serving also as a fall prevention plate is disposed on the back of the sound absorbing material.

In this case, it is preferable to use a synthetic fiber non-woven fabric block having a higher density than other synthetic fiber non-woven fabric blocks for the sound absorbing material synthetic fiber non-woven fabric block located on the back plate side.

As a result, it is possible to improve the effect of reducing low-frequency noise caused by the vehicle traveling on the viaduct.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a sound absorbing member of the present invention and a soundproof wall using the sound absorbing member will be described with reference to the drawings.

FIG. 1 shows an embodiment of the sound absorbing member of the present invention. The sound absorbing member 1 is made of a surface plate 11 made of a metal plate material having a large number of openings, such as aluminum, rust-proof expanded metal, punched metal, and a louver structure.
And a sound absorbing material 12 made of a synthetic fiber non-woven fabric block, and a unit block whose periphery is covered with a frame member 13 made of a metal plate material subjected to a rust-proof treatment.

Among these, the synthetic fiber non-woven fabric block constituting the sound absorbing material 12 has a polyvinylidene chloride fiber having high water resistance against rainwater and the like and chemical resistance against exhaust gas and the like, and a weather resistance of the polyvinylidene chloride fiber. As a bridging agent made of a synthetic resin material, the fibers having a lower melting point than polyvinylidene chloride fibers such as polyester fibers are entangled, and the polyvinylidene chloride fibers are bonded by heating the entire body to melt the fibers having a low melting point. Thus, it is formed into a predetermined shape. This synthetic fiber nonwoven fabric block can be used as it is without covering the surface of the sound absorbing material with a synthetic resin film like a conventional sound absorbing material made of glass wool.

In this case, the polyvinylidene chloride fiber has a denier of 10 to 100, preferably 20 to 40.
Fibers having a lower melting point than polyvinylidene chloride fibers such as polyester fibers used for the bridging agent are 1 to 10 denier, preferably 2 to 10 denier.
5 denier is used, and both use 98 to 60% by weight of polyvinylidene chloride fiber, preferably 90 to 90% by weight.
70% by weight of low melting fiber, 2-40
% By weight, preferably 10 to 30% by weight,
It is preferable to bind the polyvinylidene chloride fiber by binding the two and melting the low melting point fiber. As a result, it is possible to obtain a synthetic fiber nonwoven fabric block that is uniform and hard to lose its shape.

The sound absorbing material 12 may have a large number of irregularities (not shown) on its surface, more specifically, irregularities of about 3 to 10 mm when formed, if necessary.
Furthermore, the sound absorbing material 12 can also form a cavity at the center thereof, thereby reducing the amount of the sound absorbing material used without deteriorating the sound absorbing performance.

As shown in FIG. 2, the sound absorbing member 1 can be provided with a space 3 in front of a side wall 2 made of concrete or the like with a space 3 therebetween to form a soundproof wall. In this case, when arranging the sound absorbing member 1 on the front surface of the side wall 2,
Although not particularly limited, the frame member 13 of the sound absorbing member 1 is fixed to the angle iron 41 fixed vertically to the side wall 2 with an anchor bolt or the like via a fixing bracket 42 by a bolt.
Then, the sound absorbing members 1 are sequentially stacked up to a predetermined height to construct a soundproof wall.

As shown in FIG. 3, the sound absorbing member 1 is provided with a back plate 14 made of a rust-proof metal plate with a space 15 provided on the back of the sound absorbing member 1.
Frame member 13 made of a metal plate material in which space 15 has been rust-proofed
It can be configured as a unit block 10 sealed by a. In this case, the soundproof wall is constructed by inserting and fixing the unit block 10 to a post made of rust-proofed H-shaped steel or the like, or by directly fixing it to the side wall made of concrete.

FIG. 4 shows a modification of the sound absorbing member of the present invention.
This sound absorbing member 1 ′ is configured by combining a sound absorbing material 12 made of the synthetic fiber nonwoven fabric block of the sound absorbing member 1 shown in FIG. 1 with a plurality of synthetic fiber nonwoven fabric blocks 12-1 and 12-2 having different densities. Other basic configurations are the same as those of the sound absorbing member 1 shown in FIG.

As described above, by constructing the sound absorbing material by combining a plurality of synthetic fiber nonwoven fabric blocks 12-1 and 12-2 having different densities, noise in a wide range of frequencies can be efficiently reduced.

In this case, the synthetic fiber non-woven fabric blocks 12-1 and 12- of the sound absorbing material are provided so that the noise reduction effect of a wide range of frequencies can be obtained while increasing the noise incidence rate.
2 is a synthetic fiber nonwoven fabric block 12-1 of a sound absorbing material which is laminated in the noise incident direction and located on the noise incident side.
Preferably, a synthetic fiber non-woven fabric block having a lower density than the synthetic fiber non-woven fabric block 12-2 on the back side is used.

The sound absorbing member 1 'shown in FIG.
Can be used in the same manner as the sound absorbing member 1 shown in FIG.

The sound-absorbing member of the present invention can be used for the sound-absorbing device and the fall-preventing device provided below the viaduct floor slab, which the present inventors have previously proposed, in addition to the above soundproof wall. 5 to 9 show examples of these devices.

As shown in FIGS. 5 and 6, a sound absorbing device 7 for covering a substantially entire lower surface of the floor slab 51 so as to form a predetermined working space 6 below the floor slab 51 of the viaduct 5.
Is provided. The sound absorbing device 7 is provided with a permanent scaffold that is permanently installed so that the worker enters the work space 6 and repairs the lower surface of the floor slab 51 and repairs the steel material used for the bridge girder 52. It also serves as paint, rebar,
Roads 8 where work materials such as concrete and work tools are located below
It is provided so as to cover substantially the entire lower surface of the floor slab 51 so that there is no gap to fall upward. This eliminates the need to assemble a scaffold each time repair work is performed, as is the case with conventional temporary scaffolds. This improves safety, improves the work environment for repair work, and improves work efficiency. In addition, during the repair work, the working materials such as paints, reinforcing bars, and concrete, and working tools do not drop, and therefore, the vehicle traveling on the lower road 8 is not damaged. Therefore, it is possible to reduce the compensation cost associated therewith.
The height H of the working space 6 is set to a height at which the repair work such as the repair of the lower surface of the floor slab 51 or the painting of the steel material used for the bridge girder 52 can be easily performed, for example, about 1 to 2 m. It is preferable to set.

The sound absorbing device 7 includes an erecting member 72 made of H-shaped steel disposed on the bridge girder 52 of the viaduct 5, and the erecting member 72.
And a sound absorbing member 1A fixed via a fixing member 73.

As shown in FIG. 7, the sound absorbing member 1A is made of aluminum, expanded metal treated with rust prevention,
A surface plate 11A made of a plate material having a number of openings such as a punching metal and a louver structure, and having a bulging portion projecting outward in a strip shape extending along the longitudinal direction of the viaduct 5;
A sound absorbing material 12A made of the same synthetic fiber nonwoven fabric block as the sound absorbing member 1 described above, and on the back of the sound absorbing material 12A,
A back plate 14A also serving as a scaffold plate having a large number of openings, such as aluminum, rust-proof expanded metal, punched metal, and a louver structure, is provided. And is connected by a frame member 13A. In this case, the back plate 14A and the frame member 13A may be formed by integrally molding the aluminum plate by aluminum extrusion.

FIG. 8 shows a modification of the sound absorbing member 1A. This sound absorbing member 1A 'is composed of a sound absorbing material 12A made of the synthetic fiber nonwoven fabric block of the sound absorbing member 1A shown in FIG. 7 and a plurality of synthetic fiber nonwoven fabric blocks 12A-1 and 12A- having different densities.
2, and 12A-3, and a hollow 15A is formed at the center of the synthetic fiber nonwoven fabric block 12A-2. The other basic configuration is the sound absorbing member 1A shown in FIG.
Is the same as

In this case, the sound-absorbing synthetic fiber non-woven fabric block 12A-1 located on the side of the back plate 14A where the noise of the vehicle traveling on the viaduct 5 penetrates through the floor slab 51 of the viaduct 5 is provided with another noise. Synthetic fiber non-woven fabric block 1
It is preferable to use a high-density synthetic fiber nonwoven fabric block having a higher effect of reducing noise at lower frequencies than 2A-2 and 12A-3. Further, the synthetic fiber nonwoven fabric blocks 12A-2 and 12A-3 of the sound absorbing material are provided so that the noise reduction effect of a wide range of frequencies can be obtained while increasing the noise incidence rate.
While being laminated in the noise incident direction, the synthetic fiber nonwoven fabric block 12A-2 of the sound absorbing material located on the noise incident side includes:
It is preferable to use a synthetic fiber nonwoven fabric block having a lower density than the synthetic fiber nonwoven fabric block 12A-3 on the back side.

As described above, the sound absorbing material is made of a plurality of synthetic fiber nonwoven fabric blocks 12A-1, 12A-2, 12
By combining A-3, noise in a wide range of frequencies can be efficiently reduced, and by forming a cavity 15A in the center of the synthetic fiber nonwoven fabric block 12A-3, the sound absorption performance is improved. In this case, the amount of the sound absorbing material used can be reduced.

The sound absorbing member 1A 'shown in FIG. 8 can be used in the same manner as the sound absorbing member 1A shown in FIG.

As shown in FIGS. 5 and 6, on both outer sides of the sound absorbing device 7 in the width direction of the viaduct 5, columns 95 made of H-section steel whose ends are fixed to the floor slab 51 and the sound absorbing device 7 are arranged. The column 95 is provided with the fall prevention device 9. The fall prevention device 9 is used to prevent work materials such as paints, reinforcing bars, and concrete, work tools, and the like from dropping on the road 8 and the worker from falling down during repair work on the side wall 53 and the like of the viaduct 5. The extension is provided along the longitudinal direction of the viaduct 5 and is usually installed at a storage position below the floor slab 51 of the viaduct 5, and an adjusting tool 92 such as a chain is used during repair work. By operating it, it swings around the hinge 91 and is installed at the projecting position 9 ′ outside the lower side wall 53 of the viaduct 5. The fall prevention device 9
The overhang width W is a width that can prevent work materials such as paint, reinforcing steel, concrete, work tools, and the like from dropping on the road 8 and a worker from falling down during repair work of the side wall 53 of the viaduct 5 and the like. For example, it is preferable to set the distance to about 1 m. Further, in the present embodiment, the fall prevention device 9 is provided with the fixed portion 96 for the convenience of setting the height H of the work space 6 to be large, but the height H of the work space 6 and the tension of the fall prevention device 9 are set. The fixed portion 96 may be omitted according to the width W.

The fall prevention device 9 is provided with a sound absorbing member 1B on a frame member 93 made of rust-proofed steel or aluminum so as to reduce noise of a vehicle running on a road below the viaduct. Arrange and configure.

As shown in FIG. 9, this sound absorbing member 1B
A bulging portion that has a large number of openings, such as aluminum, rust-proof expanded metal, punched metal, and a louver structure, that is located on the side visible from the road 6 and that protrudes outward in a strip shape extending along the longitudinal direction of the viaduct 5. A sound absorbing material 12B made of a synthetic fiber nonwoven fabric block similar to the sound absorbing member 1 described above,
On the back surface of the sound absorbing material 12B, a back plate 14B serving also as a fall prevention plate made of a plate material having a large number of openings made of rust-proofed aluminum or the like or a plate material having no openings is provided. 14B is connected to a back plate 14B made of aluminum or the like by a frame member 13B integrally formed.

[0039]

According to the sound absorbing member of the present invention, since the synthetic fiber non-woven fabric block is used as the sound absorbing material, the glass wool scatters and causes environmental destruction as in the case of the conventional sound absorbing material made of glass wool. Without
In addition, colors can be easily applied. This eliminates the need to cover the surface of the sound absorbing material with a synthetic resin film,
It is possible to obtain a sound-absorbing member which is inexpensive in manufacturing cost, has high durability, and does not destroy the surrounding environment and can give a color in harmony with the surrounding environment.

Further, the synthetic fiber nonwoven fabric block is formed by binding polyvinylidene chloride fibers and binding the polyvinylidene chloride fibers with a bridging agent made of a synthetic resin material having weather resistance, thereby forming a block against rainwater and the like. It is possible to obtain a sound absorbing material having high water resistance and chemical resistance to exhaust gas and the like, and to improve the durability of the sound absorbing member.

Further, by using a fiber having a lower melting point than polyvinylidene chloride fiber such as polyester fiber for the bridging agent, the fiber having a lower melting point than polyvinylidene chloride fiber such as polyester fiber can be entangled with the polyvinylidene chloride fiber. By heating the entire body to melt the low-melting fiber, the polyvinylidene chloride fiber can be bonded, and a homogeneous, non-deformable synthetic fiber nonwoven fabric block can be obtained. A fiber having a melting point of 10 to 100 denier, a fiber having a lower melting point than polyvinylidene chloride fiber such as a polyester fiber used as a bridging agent, and a fiber having a denier of 1 to 10 denier are used. 98 to 60% by weight of vilinidene fiber and 2 to 40% of low melting point fiber. Used at a ratio of amount%, with is Matoi絡 both, by melting the low melting point fiber, by coupling the polychlorinated Biriniden fibers, it is possible to obtain a more homogeneous synthetic fiber nonwoven fabric block.

Further, by constructing the sound absorbing material by combining a plurality of synthetic fiber nonwoven fabric blocks having different densities,
Noise of a wide range of frequencies can be reduced efficiently,
In particular, by using a synthetic fiber non-woven fabric block having a lower density than the synthetic fiber non-woven fabric block on the back side of the synthetic fiber non-woven fabric block of the sound absorbing material located on the noise incident side,
The effect of reducing noise in a wide range of frequencies can be obtained while increasing the incidence rate of noise, and the sound absorbing member located on the back plate side that also serves as a scaffold plate of a sound absorbing member of a sound absorbing device provided below the elevated bridge slab. By using a synthetic fiber nonwoven fabric block having a higher density than other synthetic fiber nonwoven fabric blocks as a material, it is possible to improve the effect of reducing low-frequency noise caused by a vehicle running on a viaduct.

In the sound absorbing member of the present invention, the sound absorbing member is provided with a space in front of a side wall made of concrete or the like to form a soundproof wall, or the back plate is provided with a space in the back of the sound absorbing member. In addition to being able to form a soundproof wall by arranging, the surface plate is formed into a shape having a bulging portion protruding outward, and the back of the sound absorbing material also serves as a scaffold plate having a large number of openings. By arranging and configuring the face plate, as a sound absorbing member of a sound absorbing device provided below the viaduct floor slab, the surface plate is formed in a shape having a bulging portion projecting outward, and a sound absorbing material is formed. By arranging a back plate which also serves as a fall prevention plate on the back surface of the device, it can be used as a sound absorbing member of the fall prevention device, and each has the same effect as the above sound absorbing member.

[Brief description of the drawings]

1A and 1B show an embodiment of a sound absorbing member of the present invention, in which FIG. 1A is a front view, FIG. 1B is a side longitudinal sectional view, and FIG.

FIGS. 2A and 2B show an example of a soundproof wall using the sound absorbing member of the present invention, wherein FIG. 2A is a cross-sectional plan view, FIG. 2B is a front view, and FIG. 2C is a cross-sectional view taken along line AA of FIG. is there.

3A and 3B show an example of a soundproof wall using the sound absorbing member of the present invention, wherein FIG. 3A is a front view and FIG.

4A and 4B show a modification of the sound absorbing member of FIG. 1, wherein FIG. 4A is a front view, FIG. 4B is a side longitudinal sectional view, and FIG.

FIG. 5 is a schematic perspective view of a viaduct provided with a sound absorbing device and a fall prevention device.

FIG. 6 is a sectional view of the main part.

FIG. 7 is a sectional view showing an example of a sound absorbing member used in the sound absorbing device.

FIG. 8 is a cross-sectional view showing a modification of the sound absorbing member of FIG.

FIG. 9 is a cross-sectional view illustrating an example of a sound absorbing member used in the fall prevention device.

FIG. 10 is a cross-sectional view showing the structure of a conventional soundproof wall.

[Explanation of symbols]

1, 1 ', 1A, 1A', 1B Sound absorbing member 11, 11A, 11B Surface plate 12, 12-1, 12-2, 12A, 12A-1, 12
A-2, 12A-3, 12B Sound absorbing material 14 Back plate 14A, 14B Back plate 15 Space 15A Cavity 2 Side wall 3 Space 5 Viaduct 51 Floor slab 52 Bridge girder 53 Side wall 7 Sound absorbing device 8 Road 9 Fall prevention device

Claims (10)

[Claims] 1. A sound absorbing member using a synthetic fiber nonwoven fabric block as a sound absorbing material. 2. A synthetic fiber non-woven fabric block formed by binding polyvinylidene chloride fibers with each other and binding the polyvinylidene chloride fibers with a bridging agent made of a synthetic resin material having weather resistance. Item 2. The sound absorbing member according to Item 1. 3. The sound-absorbing member according to claim 2, wherein the bridging agent is made of a fiber having a lower melting point than polyvinylidene chloride fiber such as polyester fiber. 4. Entangling 10 to 100 denier polyvinylidene chloride fibers and fibers having a lower melting point than polyvinylidene chloride fibers such as 1 to 10 denier polyester fibers, and melting the low melting point fibers. 4. The sound absorbing member according to claim 3, wherein polyvinylidene chloride fibers are bonded. 5. A polyvinylidene chloride fiber of 98 to 60% by weight and a fiber having a melting point lower than that of polyvinylidene chloride such as a polyester fiber of 2 to 40% by weight are entangled, and the low melting point fiber is melted. The sound absorbing member according to claim 3 or 4, wherein the polyvinylidene chloride fiber is bonded. 6. The sound-absorbing member according to claim 1, wherein the sound-absorbing material is constituted by combining a plurality of synthetic fiber nonwoven fabric blocks having different densities. 7. A synthetic fiber nonwoven fabric block having a lower density than the synthetic fiber nonwoven fabric block on the back side is used for the synthetic fiber nonwoven fabric block located on the noise incident side while the synthetic fiber nonwoven fabric blocks are laminated in the noise incident direction. The sound-absorbing member according to claim 1, 2, 3, 4, 5, or 6. 8. A front plate is formed in a shape having a bulging portion protruding outward, and a back plate serving also as a scaffold plate having a large number of openings is arranged on the back surface of the sound absorbing material. The sound absorbing member according to claim 1, 2, 3, 4, 5, 6, or 7, wherein the sound absorbing member is used for a sound absorbing device provided below a viaduct floor deck. 9. The sound absorbing material according to claim 8, wherein a synthetic fiber nonwoven fabric block having a higher density than other synthetic fiber nonwoven fabric blocks is used for the synthetic fiber nonwoven fabric block of the sound absorbing material located on the back plate side. Element. 10. A front plate is formed in a shape having a bulging portion protruding outward, and a back plate serving also as a fall prevention plate is arranged on the back surface of the sound absorbing material to prevent fall of a viaduct. Claim 1, 2, 3, 4, characterized in that it is used for an apparatus.
The sound absorbing member according to 5, 6, or 7.