Soundproof structure and sound absorbing material for bridge

Abstract

To facilitate the procurement of materials and to improve workability.SOLUTION: An outer sound absorbing material 31 fitted to close an end space below the expansion device 29 at both ends in the longitudinal direction of the expansion gap 23 corresponding to the width direction of the bridge, and an inner sound absorbing material 41 fitted to close an internal space sandwiched between the end spaces in the expansion gap 23 are provided. A main body 32,42 of the outer sound absorbing material 31 and the inner sound absorbing material 41 is formed of a sound absorbing sponge, and at least a main body 42 of the inner sound absorbing material 41 has a structure in which a mat-like sound absorbing sponge is equally folded in two. The inner sound absorbing material 41 is formed so that the length of a part corresponding to the longitudinal direction of the expansion gap part 23 is shorter than a half of the longitudinal length of the expansion gap part 23, and a plurality of inner sound absorbing materials 41 are fitted while being supplemented. A sound insulation layer 33,43 made of metal is formed on the outer surfaces of the outer sound absorbing material 31 and the inner sound absorbing material 41, which are exposed to the outside when the outer sound absorbing material 31 and the inner sound absorbing material 41 are fitted into the expansion gap 23.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a soundproofing structure for suppressing noise generated from below an expansion joint of a bridge. [Background technology]

[0002] In order to suppress noise on bridges, the space below the expansion device in the gap is sealed, as disclosed in the following Patent Documents 1 and 2. Here, the gap is a gap provided to prevent damage from collisions even if expansion, contraction, or deformation occurs at the joint between the bridge and abutment, and an expansion device is provided above the gap to fill the gap.

[0003] The structure of Patent Document 1 involves attaching a long, U-shaped groove-shaped soundproofing device with a multi-layered noise-absorbing material inside to the underside of the road with bolts to cover the underside of the joint (gap). The flange at the top of the soundproofing device has elongated holes for bolt attachment to accommodate expansion and contraction of the gap. The structure of Patent Document 2 involves using a water-stopping and sound-absorbing material made by covering the outside of a porous material such as urethane foam with a rubber sheet and folding it in half. The water-stopping and sound-absorbing material is inserted into the gap with the fold line facing up, and adhesive is filled in the space above the inserted water-stopping and sound-absorbing material.

[0004] In addition to these structures that close off the area below the gap or the gap itself, there is also a structure in which the opening on the underside of the gap is covered with a water-resistant sound-absorbing panel material, as in Patent Document 3. The panel material is formed in a box shape so that the sound-absorbing surface covers the opening away from it, and by having a structure in which the left and right halves are separated and overlap each other, it can follow the expansion and contraction of the gap.

[0005] In a configuration like that of Patent Document 1, the elongated holes must be fixed so that they can adequately accommodate expansion and contraction of the gap, which is not an easy task. In the configuration of Patent Document 2, the filling of adhesive is required, so construction is not possible without traffic restrictions. In contrast, Patent Document 3 has a structure in which the panel material is fixed to the superstructure of the bridge from below, and simply fixing it in place will naturally accommodate expansion and contraction of the gap, so it is relatively easy to install compared to configurations like Patent Documents 1 and 2, which block the space.

[0006] However, each of these structures requires specialized components, so materials must be prepared according to the construction requirements, which sometimes makes it difficult to respond flexibly to construction requests. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 53-48329 [Patent Document 2] Japanese Patent Application Publication No. 54-26028 [Patent Document 3] Patent No. 4982767 Summary of the Invention [Problem to be solved by the invention]

[0008] The main object of this invention is to make it possible to easily procure materials and improve workability. [Means for solving the problem]

[0009] To this end, the present invention provides the following soundproof structure for bridges.

[0010] That is, the bridge's soundproofing structure uses an outer sound-absorbing material and an inner sound-absorbing material. The outer sound-absorbing material is a member fitted to seal end spaces below the expansion joint at both ends of the longitudinal gap, which corresponds to the width of the bridge. The inner sound-absorbing material is a member fitted to seal the internal space, which is an open space below the expansion joint in the gap, including the lower part of the superstructure, and is sandwiched between the end spaces. The main bodies of the outer sound-absorbing material and the inner sound-absorbing material are made of flexible sound-absorbing mats, and at least the main body of the inner sound-absorbing material has a structure in which the sound-absorbing mat is folded in half equally. A plurality of inner sound-absorbing materials are provided, with the length of the portion corresponding to the longitudinal direction of the gap shorter than half the longitudinal length of the gap. A sound-insulating layer is formed on the outer surfaces of the outer sound-absorbing material and the inner sound-absorbing material, which are exposed to the outside when the outer sound-absorbing material and the inner sound-absorbing material are fitted into the gap. Of these two types of sound-absorbing materials, multiple inner sound-absorbing materials are inserted sequentially into the gaps with the folded back parts facing downwards to close the interior space.Then, the outer sound-absorbing material is fitted into the end space to close the end space and come into contact with the end face of the opposing inner sound-absorbing material.

[0011] In this configuration, the end and interior spaces below the expansion joint in the gap are closed off with sound-absorbing materials, namely the outer and inner sound-absorbing materials. The interior spaces are closed off by inserting the inner sound-absorbing material, whose length is shorter than half the longitudinal length of the gap, along the length of the gap. Because the end and interior spaces are closed off and there is no space open to the outside, noise generated near the expansion joint does not leak directly, but is reflected, transmitted, and absorbed by the sound-absorbing mat that forms the main body of the sound-absorbing material. Where the sound attempts to escape to the outside while attenuating, it is reflected off the opposing surfaces of the bridge components and the sound-insulating layer, thereby insulating it. The main bodies of the outer and inner sound-absorbing materials are obtained by cutting the sound-absorbing mat, and the sound-insulating layer can be formed by attaching a sheet material with sound-insulating properties, so the outer and inner sound-absorbing materials can be prepared on-site. In the case of an inner sound-absorbing material whose main body has a bifold structure, it is possible to reduce the thickness of the sound-absorbing mat required, and it can naturally follow the expansion and contraction of the gap. [Effects of the Invention]

[0012] According to this invention, the outer and inner sound-absorbing materials can be made from a versatile sound-absorbing mat and a sound-insulating sheet material, and the construction using these materials is simple, making it easy to procure the materials (outer and inner sound-absorbing materials) needed to construct the soundproof structure. The materials can also be cut on-site to tailor them to the construction requirements, making it easy to carry out appropriate and flexible construction according to requirements. Furthermore, construction is carried out by fitting the outer and inner sound-absorbing materials into the designated positions in the gaps, which also simplifies the process, eliminating the need for traffic restrictions. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing an outline of a soundproofing structure for a bridge. [Figure 2] Schematic diagram of bridge structure. [Figure 3] Cross sections AA and BB in Figure 2. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 4 is a perspective view showing the state before the inner sound-absorbing material is folded. [Figure 7] Side view of the inner sound absorbing material. [Figure 8] FIG. 1 is a perspective view showing a construction mode of a soundproofing structure for a bridge. [Figure 9] Cross-sectional views of the bridge soundproofing structure, corresponding to the AA and BB cross-sectional views in Figure 2. [Figure 10] A diagram showing noise measurement locations on a bridge. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described below with reference to the drawings.

[0015] FIG. 1 shows an outline of a bridge soundproofing structure 11 (hereinafter referred to as "soundproofing structure").

[0016] The soundproof structure 11 is applied to a gap 23 between a superstructure 21 and a substructure 22 in a bridge structure 12 as shown in FIG. 2, and to a gap 23 within the superstructure 21.

[0017] Figure 2 is a schematic diagram of the bridge structure 12, and here we will briefly explain the superstructure 21 and substructure 22. First, the substructure 22 is made up of abutments 24, piers 25, and the foundations (not shown) that support them. The abutments 24 connect the road 26 and piers 25 at both ends of the bridge and are configured to support the load and soil behind them. The piers 25 are installed in the middle of the bridge and are configured to support the load from the superstructure 21.

[0018] Next, the superstructure 21 is composed of the main body of the superstructure 21, i.e., the bridge 27 spanning between the abutments 24 and piers 25 or between the abutments 24, bearings 28, expansion devices 29, and bridge fall prevention devices (not shown). The bearings 28 are a structure that supports the bridge 27 on the abutments 24 or piers 25 and transmits the load from the superstructure 21 to the substructure 22. They are fixed to the support surfaces 24a, 25a of the abutments 24 or piers 25 that face the underside of the bridge 27. The expansion devices 29 are a structure that fills the upper part of the gaps 23, which are provided to prevent adjacent members from colliding and being damaged even if the superstructure 21 moves due to expansion and contraction of the bridge due to temperature changes or drying shrinkage, or during an earthquake. The bridge fall prevention devices (not shown) prevent the superstructure 21 from falling due to an earthquake or the like, and are provided below the expansion devices 29.

[0019] With this structure, a gap 23 is formed at least between the abutment 24 and the bridge 27.

[0020] Figure 3 shows the AA and BB cross sections of Figure 2, respectively, in Figure 3(a) and (b). As shown in Figure 3(a), the bearings 28 are arranged at intervals in the width direction of the bridge. In contrast, the expansion joints 29 are formed long in the width direction of the bridge, as shown in Figure 3(b), and are installed so as to straddle the gap between the abutment 24 and the bridge 27, and between the bridges 27.

[0021] For this reason, the gap section 23 has an expansion device 29 at its upper end, and the space below it is a long, narrow space with a vertically long rectangular cross section that extends in the width direction of the bridge, sandwiched between the vertical opposing surfaces of the bridge 27 and the abutment 24, or between the vertical opposing surfaces of the bridges 27.

[0022] The soundproof structure 11 closes the gap 23 of this shape, in other words, closes the part of the gap 23 of the bridge structure 12 that is open to the outside, thereby preventing the propagation of noise, and is composed of an outer sound-absorbing material 31 and an inner sound-absorbing material 41 that are fitted into the gap 23, as shown in Figure 1. Of these, the inner sound-absorbing material 41 corresponds to the "sound-absorbing material" set forth in claim 3.

[0023] The outer sound-absorbing material 31 is fitted to close end spaces 23c (see FIG. 3(b)) below the expansion device 29 at both ends of the longitudinal direction of the gap 23, which corresponds to the width direction of the bridge. The depth d of the end spaces 23a (the length in the direction corresponding to the width direction of the bridge) is not particularly determined and can be set as appropriate.

[0024] The inner sound-absorbing material 41 is fitted to close the inner space 23b, which is an open space below the expansion joint 29 in the gap section 23 and includes the lower part of the superstructure 21, and is sandwiched between the end spaces 23a. Specifically, the inner space 23b is the part of the space extending upward from the support surfaces 24a, 25a of the abutments 24 and piers 25 at their lower ends, excluding the end spaces 23a. The "lower part of the superstructure 21" refers to the main body of the superstructure 21, i.e., the lower part of the vertical length (thickness) of the bridge 27. Therefore, the height h1 of the inner space 23b is higher than the height h2 of the space open below the bridge 27 (see FIG. 3(b)). Because the height h1 of the inner space 23b is higher than the height h2 of the space below the bridge 27, the inner sound-absorbing material 41 separates the gap section 23 from the space below the bridge 27.

[0025] The basic structure of the outer sound-absorbing material 31 and the inner sound-absorbing material 41 is the same. That is, the main bodies 32, 42 of the outer sound-absorbing material 31 and the inner sound-absorbing material 41 are made of flexible sound-absorbing mats. When the main bodies 32, 42 are fitted into the gap portion 23 on the outer surfaces of the main bodies 32, 42, sound-insulating layers 33, 43 are formed on the portions that are exposed to the outside and do not come into contact with the opposing surfaces of the abutment 24, bridge 27, etc.

[0026] Sound-absorbing mats are made of sound-absorbing sponges made of synthetic resin or synthetic rubber, or sound-absorbing wool made of compressed fibers. Sound-absorbing wool fibers include glass wool and polyethylene terephthalate. From the viewpoint of elasticity, sound-absorbing sponges made of open-cell urethane sponges are suitable. In this case, the density of the sound-absorbing sponge should be 15 kg / m. 3 ~45kg / m 3 It is preferable that the 3 ~35kg / m 3 It would be good if that were the case.

[0027] The sound-insulating layers 33, 43 can be made of metals commonly used for sound insulation, such as lead and aluminum alloys, as well as rubber, which has a high specific gravity. A rust-resistant material is preferable. The specific gravity of rubber should be, for example, about 7.5. The sound-insulating layers 33, 43 are formed by attaching plates or sheets made of metal or rubber.

[0028] To explain the structures of the outer sound-absorbing material 31 and the inner sound-absorbing material 41 in detail, first, the outer sound-absorbing material 31 is prismatic, as shown in Figure 4. The length a and width b of the main body 32 correspond to the opening of the end space 23a, and it is preferable to make them slightly larger so that they can be pressed into place. The thickness c of the main body 32 is equal to or slightly longer than the depth d of the end space 23a. The main body 32 is formed by cutting a sound-absorbing mat, but sound-absorbing mats can be joined together if necessary to achieve the desired thickness. The illustrated example shows two sound-absorbing mats superimposed and integrated with adhesive or double-sided adhesive tape. The sound-absorbing mats that make up the main body 32 can also be constructed by adding sections in the longitudinal or lateral directions.

[0029] A sound-insulating layer 33 is formed on the outer surface that is exposed to the outside when the board is fitted into the end space 23a, which is the predetermined mounting position in the gap portion 23. Fig. 4 shows an example in which the sound-insulating layer 33 is formed on the entirety of one surface in the thickness direction. The sound-insulating layer 33 may also be formed on the other surface.

[0030] The sound-insulating layer 33 is composed of a sound-insulating sheet 33a and an adhesive layer 33b for adhering the sound-insulating sheet 33a to the main body 32. A butyl rubber adhesive, for example, is preferably used for the adhesive layer 33b. Such sound-insulating sheet 33a with adhesive layer 33b is an existing product, and a commercially available product can be used.

[0031] Two such outer sound absorbing materials 31 are used for each gap 23 so that they can be attached to the end spaces 23a at both ends of the gap 23 in the longitudinal direction.

[0032] As shown in FIG. 5, the inner sound-absorbing material 41 has a rectangular plate shape overall. However, it is formed into a plate shape by folding a single mat-shaped sound-absorbing mat in half. In other words, as shown in FIG. 6, the main body 42 has a structure in which a square sound-absorbing mat of a constant thickness is folded in half equally. All four sides, including the folded-back portions 42a corresponding to the fold lines, are straight, and the angles between the sides are right angles. The length x of the portion of the main body 42 corresponding to the longitudinal length of the gap portion 23 is shorter than half the longitudinal length of the gap portion 23. Because the length x of the portion of the inner sound-absorbing material 41 corresponding to the longitudinal length of the gap portion 23 is shorter than the length of the internal space 23b into which it is fitted, multiple inner sound-absorbing materials 41 are required for one gap portion 23.

[0033] The length x of the portion corresponding to the longitudinal length of the gap portion 23 is hereinafter referred to as the "connection direction length" x, the length of the side extending vertically perpendicular to this is referred to as the "vertical length" y, and the length in the thickness direction of the sound-absorbing sponge is referred to as the "thickness" z. The connection direction length x is shorter than half the longitudinal length of the gap portion 23, but this length is appropriately set to facilitate fitting into the internal space 23b. When setting this length, it is advisable to take into consideration the size and spacing of the supports 28. The vertical length y is longer than the height h2 of the space open below the bridge 27. The thickness z is set to be longer than the length of the corresponding portion in the longitudinal cross section of the gap portion 23 (the length corresponding to the width b of the outer sound-absorbing material 31).

[0034] The main body 42 may be simply a folded sound-absorbing mat, or may have an appropriate structure such as adhesive added to maintain the folded shape. Also, a spacer may be provided in the internal space, including between the ends on the opposite side of the folded portion.

[0035] A sound-insulating layer 43 is formed on the outer surface that will be exposed to the outside when the panel is fitted into the internal space 23b, which is the specified installation position in the clearance gap 23. The sound-insulating layer 43 can be formed on the entire outer surface that is visible on the front side, or, as shown in Figure 7(a), on the entire portion of one side in the thickness direction that is visible on the front side, from the top to the bottom (near the portion corresponding to the folding line). Here, the "top" refers to a position above the height h2 of the space open below the bridge 27. This is because the sound-insulating layer 43 is formed at least on the portion that is open to the outside. For this reason, the sound-insulating layer 43 may be formed up to the top end of one side. As shown in Figure 7(b), it can also be formed on the entire portion of both sides in the thickness direction that are visible on the front side, from the top to the bottom. Figure 7(c) shows an example in which a spacer 45 is provided between the ends opposite the folding line, as described above. The spacer 45 can be a sound-absorbing mat made of the same material as the main body 42, a sound-absorbing mat of a different type from the main body 42, or any other appropriate material. The thickness z of the main body 42 can be adjusted by providing the spacer 45.

[0036] The sound-insulating layer 43 formed on the inner sound-absorbing material 41 can be made of the same material as the sound-insulating layer 33 used on the outer sound-absorbing material 31. In Fig. 5, 43a is a sound-insulating sheet, and 43b is an adhesive layer.

[0037] When the outer sound-absorbing material 31 and the inner sound-absorbing material 41 configured as described above are fitted and held in their respective mounting positions (end space 23a, inner space 23b), soundproof structure 11 is obtained. This configuration is shown in Figure 8. Note that support 28 is not shown in Figure 8.

[0038] First, the gap portion 23 is cleaned to remove any foreign matter. After that, the inner sound-absorbing material 41 is inserted into the internal space 23b of the gap portion 23. When inserting, the folded portion 42a is faced downward and the sound-insulating layer 43 is oriented toward the bearing 28. Side insertion should be performed sequentially from the longitudinal end of the gap portion 23. The space between the bearings 28 can be used to move the inserted inner sound-absorbing material 41. If size allows, the inner sound-absorbing material 41 may be inserted from the space between the bearings 28.

[0039] The successively fitted inner sound absorbing materials 41 are butted against the joint surfaces 44 of adjacent inner sound absorbing materials 41 with no gap between them, with the end surfaces, i.e., the surfaces facing the longitudinal direction of the gap portion 23 when fitted, serving as joint surfaces 44.

[0040] After fitting the inner sound-absorbing material 41, the outer sound-absorbing material 31 is fitted into the end space 23a. The joining surface 34 of the outer sound-absorbing material 31, i.e., the surface opposite to the surface on which the sound-insulating layer 33 is formed, is brought into close contact with the joining surface 44 of the opposing inner sound-absorbing material 41.

[0041] The inner sound-absorbing material 41 and the outer sound-absorbing material 31 fitted into the gap portion 23 in this manner can be maintained in this fitted state, if necessary, by pressing a plate material (not shown) against the sound-absorbing material visible from the opening (outer sound-absorbing material 31, inner sound-absorbing material 41) or by bonding it with adhesive.

[0042] 9(a) shows a state in which the sound-absorbing materials 31 and 41 are fitted, i.e., a cross-sectional view corresponding to FIG. 3(a) of the soundproof structure 11, and FIG. 9(b) shows a cross-sectional view corresponding to FIG. 3(b). In this way, most of the portions of the internal space 23b and the end space 23a of the gap portion 23 that are open to the outside are closed by the sound-absorbing materials 31 and 41.

[0043] In the soundproof structure 11 configured in this manner, the space below the expansion joint 29 in the gap section 23 is blocked by the outer sound-absorbing material 31 and the inner sound-absorbing material 41. Therefore, noise generated near the expansion joint 29 is reflected, transmitted, and absorbed by the main bodies 32, 42 of the outer sound-absorbing material 31 and the inner sound-absorbing material 41. Since the sound-insulating layers 33, 43 are formed in the areas where the sound tries to escape to the outside while being attenuated, the sound is reflected by the sound-insulating layers 33, 43, thereby blocking the sound. This prevents direct leakage of noise and has the effect of suppressing surrounding noise.

[0044] The inner sound-absorbing material 41, whose main body 42 has a bifold structure, allows the required thickness of the sound-absorbing mat to be thin, and can naturally follow the expansion and contraction of the gap 23. As a result, the soundproof structure 11 is well maintained.

[0045] Furthermore, the construction of the soundproof structure 11 is performed by fitting the outer sound-absorbing material 31 and the inner sound-absorbing material 41 into the gap 23, so there is no need to restrict traffic. This makes construction easy.

[0046] Moreover, the internal space 23b is closed by fitting a plurality of inner sound absorbing materials 41 in the longitudinal direction of the gap 23, which makes the work easier than when handling long objects.

[0047] Furthermore, the main bodies 32, 42 of the outer sound-absorbing material 31 and the inner sound-absorbing material 41 are obtained by cutting sound-absorbing mats, and the sound-insulating layers 33, 43 are formed by attaching sound-insulating sheets 33a, 43a. Therefore, the outer sound-absorbing material 31 and the inner sound-absorbing material 41 can be prepared on-site, rather than being pre-processed in a factory. In other words, since the materials can be cut on-site and prepared according to the construction details, appropriate and flexible construction can be easily performed according to requirements.

[0048] Regarding the above-mentioned soundproofing structure 11, noise measurements were carried out before and after construction to confirm the noise prevention effect.

[0049] The outer sound-absorbing material 31 and inner sound-absorbing material 41 used had main bodies 32, 42 made of urethane sponge, and sound-insulating layers 33, 43 made of aluminum alloy. The gap at the gap 23 was 150 mm, and the height was approximately 1000 mm. The outer sound-absorbing material 31 had a horizontal length b of 150 mm, and its height was also adjusted to match the gap 23. The thickness c of the main body 32 was 100 mm. The inner sound-absorbing material 41 used a sound-absorbing sponge that was 60 mm thick for the main body 42. 25 mm thick glass wool was also provided as a spacer. The vertical length y was 770 mm.

[0050] The measurement locations are shown in Figure 10. As shown in this figure, measurements were taken at one end of a bridge with sidewalks 12a on both the left and right sides and a roadway 12b between them. Specifically, measurements were taken at the left and right sidewalks 12a (measurement points A and F) on the road 26 opposite the bridge 27, at the parts of the sidewalks 12a on both sides where the expansion joints 29 are located (measurement points B and E), and under the bridge 27 (measurement points C and D), 1.5 m above ground. The measurement points under the bridge 27 were located about 2 m inward from both the left and right ends of the bridge 27, about 3.5 m from the abutment 24, and measurements were taken toward the soundproofing structure 11.

[0051] Measurements before and after construction were carried out on the same day of the week at the same time to minimize the difference in traffic volume. The equivalent sound level for a certain period of time was determined using a sound level meter (sound level meter) specified in C 1509-1.

[0052] The measurement results are shown in Table 1.

[0053] [Table 1] That is, before construction, the noise level at all measurement points exceeded 80 dB, which is considered "extremely loud," but after construction, all except measurement point C dropped to the 50 dB range. A noise level in the 50 dB range is considered "normal," which shows that there was a considerable soundproofing effect.

[0054] Thus, a good noise prevention effect was obtained.

[0055] The above-described configuration is one embodiment for carrying out the present invention, and the present invention is not limited to the above-described configuration, and other configurations can also be adopted.

[0056] For example, the sound absorbing mat that constitutes the main body 42 of the inner sound absorbing material 41 (sound absorbing material) may have an uneven surface such as a wave shape on one side that faces inward when folded. [Explanation of symbols]

[0057] 11...Soundproof structure 12…Bridge structure 21...Superstructure 23...Yuma area 23a...End space 23b…Internal space 29…Expansion device 31…Outer sound absorbing material 32...Main body 33...Soundproofing layer 34…Joint surface 41…Inner sound absorbing material 42...Main body 42a...Folded section 43...Soundproofing layer 44…Joint surface

Claims

1. An outer sound-absorbing material is fitted to close the end spaces below the expansion device at both ends of the longitudinal direction of the gap, which corresponds to the width direction of the bridge, and an inner sound-absorbing material is fitted to close the internal space, which is an open space including the lower part of the superstructure below the expansion device in the gap and is sandwiched between the end spaces. The outer sound-absorbing material and the inner sound-absorbing material each have a main body made of a flexible sound-absorbing mat, At least the main body of the inner sound-absorbing material has a structure in which a sound-absorbing mat is folded in half, a plurality of the inner sound-absorbing materials are provided, each of the inner sound-absorbing materials being formed so that the length of the portion corresponding to the longitudinal direction of the gap is shorter than half the longitudinal length of the gap; a sound-insulating layer is formed on the outer surfaces of the outer sound-absorbing material and the inner sound-absorbing material that are exposed to the outside when the outer sound-absorbing material and the inner sound-absorbing material are fitted into the gap portion; The inner sound-absorbing materials are inserted into the gaps of the inner space one after another with the folded-back portions facing downwards to close the inner space, and the outer sound-absorbing materials are fitted into the end spaces to close the end spaces and come into contact with the end faces of the opposing inner sound-absorbing materials. Soundproofing structure for bridges.

2. The sound-insulating layer is formed by attaching a sound-insulating sheet with an adhesive applied to one side. The soundproofing structure for a bridge according to claim 1.

3. A sound-absorbing material that is fitted to close an open space including the lower part of the superstructure below the expansion joint in the bridge gap, The main body is a flexible sound-absorbing mat folded in half. The length of the portion corresponding to the longitudinal direction of the gap portion, which corresponds to the width direction of the bridge, is formed to be shorter than half the longitudinal length of the gap portion, When the folded part of the double fold is fitted into the gap with the folded part facing downwards, a sound-insulating layer is formed on the outer surface that is exposed to the outside. Sound-absorbing material.

4. The sound-insulating layer is formed by attaching a sound-insulating sheet with an adhesive applied to one side. The sound-absorbing material according to claim 3.

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