JP2945951B2 - Noise-reducing track structure with varying sound absorbing layer thickness - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reducing type track structure having a characteristic of absorbing and reducing noise generated by a railway train. In particular, the present invention relates to a noise reduction type track structure having a high sound absorption coefficient over a wide frequency band of noise, excellent in sound absorption characteristics, and having a varied sound absorption layer thickness.

[0002]

2. Description of the Related Art There are four main types of noise generated when a train travels. Structural sound: Noise generated by vibration of a structure such as a viaduct when a train runs. Rolling noise: Noise generated when a train wheel contacts a rail. Aerodynamic noise: Noise generated by the body tearing air. Pantograph sound: Noise generated when a pantograph rubs against an overhead line. Among them, the structure noise and the rolling noise can be reduced by devising the structure of the track.

Conventionally, as measures for preventing noise generated from a slab track during running of a train, (1) a method of laying an elastic material under a track slab (FIG. 7), and (2) installing a sound absorbing material on an upper surface of the track slab. (FIG. 8), and (3) a method of providing a recess in a track slab and spraying a ballast or the like there (FIG. 9).

FIG. 7 is a sectional view showing a track on which a conventional elastic material laying method is applied. A rail 21 is laid on the upper surface of the track slab 23 (a plate made of concrete), and an elastic material 25 (a rubber plate or the like) is laid below the track slab 23.

FIG. 8 is a sectional view showing a track on which a conventional sound absorbing material laying method has been applied. On the upper surface of the track slab 23, a sound absorbing material 27 is laid around the rail 21. The sound absorbing material 27 is formed of foamed lightweight concrete or the like.

FIG. 9 is a view showing a track on which a conventional ballast laying method is applied. (A) is a plan view, (B) is a side sectional view, and (C) is a front sectional view. Track slab 31
The concave portions 35 (13 cm deep, 20-
30 cm), and a ballast 33 (particle diameter: 1.9 to 6.4 cm) is laid in the recess. A ballast 33 is also stacked on the side of the track slab 31.

[0007]

However, in the case of the method (1) (elastic material laying method, FIG. 7), the effect of mainly suppressing the structure noise is low, but the effect of reducing the rolling noise is low. ,
Further, there is a disadvantage that it is difficult to construct the existing slab track later. (2) (Sound absorbing material laying method, FIG. 8)
In the case of (3) (ballast ballast laying method, FIG. 9), it has been pointed out that although there is a certain reduction effect on the rolling noise, there is a variation in the sound absorption frequency characteristics.

An object of the present invention is to provide a noise reduction type track structure having a high sound absorption coefficient over a wide frequency band of noise and having excellent sound absorption characteristics.

[0009]

In order to solve the above-mentioned problems, a noise-reducing type track structure of the present invention in which the thickness of a sound absorbing layer is changed is a track slab on which a rail is laid and a track slab laid on the track slab. A noise-reducing track structure having a sound absorbing layer; the sound absorbing layer being made of a porous body having open cells in which particles are dispersed , wherein the thickness of the sound absorbing layer differs in the width direction of the track slab. It is characterized by.

[0010]

[Action] When examining the sound absorption characteristics of a sound absorbing layer made of a porous body having open cells and having a uniform thickness, a frequency band (a valley) having a low sound absorption coefficient exists. Have been found by experiments by the present inventors.
The presence of such a valley of sound absorption characteristics is not preferable because noise at the frequency of the valley cannot be sufficiently reduced.
Therefore, when sound absorbing layers with different layer thicknesses were made at different locations and tested, the sound absorbing characteristics of each part complement each other, and there are no valleys in the sound absorbing characteristics, showing good sound absorbing characteristics over a wide frequency band. Was obtained.

As the sound absorbing layer in the present invention, various porous bodies having open cells can be used. Examples of such a porous body include lightweight foamed concrete, a laminate of inorganic and organic particles, and an aggregate of fibers. Particularly preferred as the sound absorbing layer is a laminate of particles mainly having a particle size of 1 to 5 mm. Even if the layer thickness is thin (several tens mm to hundred m
m), a sound absorbing layer having a high sound absorbing effect can be obtained.

As an example of the particles forming the sound absorbing layer of the present invention, the following recycled materials can be mentioned.
The term "recycled material" refers to inorganic particles obtained by crushing and classifying unburned glass, ceramics, gravel, etc. when incinerating general waste such as municipal waste in an incinerator (such as a fluidized bed incinerator). That is. Such recycled material can be adjusted to an appropriate particle size, and exhibits a sound absorbing effect when laid on a railway track slab. In addition, the price is very low (3,000 yen / m ³ (including the transportation cost, the same applies hereinafter), 300 yen / m ^{2 for} 10 cm thickness), so the soundproofing construction cost can be reduced. By the way, in the case of single-grained crushed stone No. 7 (the particle size is usually 2.5 to 5 mm), 5,500 yen / m
³ , 550 yen / m ² when spread 10cm thick. Also,
For the track bed Crushed 3,550 yen / m ^3, laid in 40cm thickness is 1,420 yen / m ^2. Since the main components of the recycled material are glass, porcelain, gravel, and the like, there is no particular problem in durability.

[0013]

Embodiments of the present invention will be described below. FIG.
It is a perspective view showing the noise reduction type track structure which changed the sound absorption layer thickness concerning one example of the present invention. FIG. 2 is a sectional view of the noise reduction type track structure of FIG.

A rail 5 is mounted on a rail fastening base 3 protruding from the track slab 2 by bolts or rail fasteners (not shown). The sound absorbing layer 1 is provided on the track slab 2 except for the rail fastening base 3. In the noise reduction type track structure of this embodiment, the sound absorbing layer 1 is thin at the center (for example, 4 cm) and thick at the periphery (for example, 10 cm). The side bank 4 provided on the side of the track slab 2 prevents the constituent particles of the sound absorbing layer 1 from spilling to the side of the track slab 2. Further, in consideration of drainage from the sound absorbing layer (not shown, the side levee 4 has a drainage hole), the center is thin and the side is thick.

In the noise reduction type track structure shown in FIGS. 1 and 2, the sound absorbing layer 1 is formed by laying down the above-mentioned recycled material (particles). When scattering of particles due to the wind pressure of a train becomes a problem in a high-speed railway (such as a bullet train), it is necessary to harden the surface of the sound absorbing layer 1 by spraying a coupling agent on the surface of the sound absorbing layer 1. If the side of the sound absorbing layer 1 is similarly hardened, the side bank 4 is not required. Note that a plate or the like may be provided instead of the side bank 4.

As an example of the spraying of the coupling agent, when the acrylic emulsion was sprayed at a rate of 1.4 kg / m ² with a jar, the surface of the sound absorbing layer (recycled material layer) 1 was connected well, and the resin was sprayed. It was also confirmed that the sound absorption characteristics of the recycled material did not change. Similar effects can be obtained by spraying a vinyl acetate resin, a urethane resin, a silicone resin, or the like instead of the acrylic emulsion. Instead of spraying the coupling agent on the surface of the sound absorbing layer 1, a method of covering the surface of the sound absorbing layer 1 with a net, or a method of packing recycled materials in a fine bag or the like and arranging them on the upper surface of the track slab 2 is used. is there.

Next, the sound absorbing characteristics of the sound absorbing layer will be described by comparing recycled materials, ballast ballast, and single-grained crushed stone No. 7. Here, the following recycled materials were used as an example of the recycled materials. Particle size distribution: 1.3 to 2.5 mm range 54.6 wt% 2.5 to 5.0 mm range 37.7 wt% Total of the above ranges 92.3 wt% Ingredients: Glass 60 wt% Ceramic pieces 20 wt% Gravel 20 wt%

Production method: General waste was pulverized after removing iron and salt from the residue incinerated in a fluidized bed incinerator. This was sieved and classified to a particle size of 1.3 to 5 mm.

FIG. 3 is a diagram showing the particle size distribution of the above-mentioned recycled material. The solid line indicates the particle size distribution of the recycled material, the range indicated by hatching in the lower left indicates the particle size distribution of the single-grained crushed stone No. 7 (JIS A 5001) as a comparative material, and the range indicated by hatching in the lower right indicates the concrete as a reference. 4 shows the particle size distribution of crushed sand for use (JISA 5005). As shown in this figure, although the particle size distribution of the recycled material and the single-grained crushed stone No. 7 are substantially similar, the recycled material has a smaller particle size distribution in the range of 1.3 to 2.5 mm. high.

FIG. 4 shows the above recycled material, single-grain crushed stone 7
It is a graph which shows the sound absorption characteristic of a signal and a ballast ballast. This graph shows the result of measurement by the reverberation room method sound absorption coefficient measurement method based on JIS A 1409. The ballast had a particle size of 1.9 to 6.4 cm, and the ballast was spread 40 cm in thickness for measurement. For other recycled materials and single-grained crushed stone No. 7, the measurement was performed by laying 10 cm in thickness.

FIG. 4 shows that the recycle material has a high sound absorption coefficient in a reverberation room method (hereinafter referred to as a sound absorption coefficient). That is, the sound absorption coefficient (solid line, black circle) of the recycled material is 315
It was confirmed that the filter had a sound absorption characteristic of 0.8 or more in the entire frequency band of 〜4000 Hz. The rolling sounds of railway vehicles cover a very wide frequency band.
It is said to be around 2,000 Hz.

On the other hand, single-grained crushed stone No. 7 (dashed-dotted line, open square) and ballast ballast (fine line, open circle) are considerably lower than recycled materials. The sound absorption characteristic curve of single-grained crushed stone 7
At first glance it looks close to the curve of recycled material, but there are considerable differences. In addition, the frequency 1,000 ~
At 1,250 Hz, the sound absorption coefficient is 0.8 or less. The sound-absorbing characteristic curve of the ballast ballast is much lower than that of recycled material or single-crushed crushed stone No. 7. After all, the sound absorption characteristics of the recycled material of the present embodiment are in a frequency band 400 that is easily perceived by human ears, even though the layer thickness is as thin as 10 cm.
It can be said that it has a good sound absorption characteristic of a sound absorption coefficient of 0.8 or more over the entire range of up to 2,000 Hz. However,
It is desirable to improve the existence of a valley having a characteristic near 1,000 Hz if possible.

Therefore, a test was conducted to further improve the sound absorption characteristics. FIG. 5 is a graph showing a change in the sound absorption characteristics when the scatter thickness (layer thickness) of the recycled material is changed. The solid black line shows the sound absorption characteristics when the layer thickness is 100 mm, the white triangle broken line shows the sound absorption characteristics when the layer thickness is 80 mm, the cross-dot-dashed line shows the sound absorption characteristics when the layer thickness is 60 mm, and the white circle thin solid line shows the layer thickness. The sound absorption characteristics in the case of 40 mm are shown.

What is notable in FIG. 5 is that the peak and bottom (valley) of the sound absorption characteristics of each line move to the left (to the lower frequency side) as the layer thickness increases. Then, each peak fills each bottom. If this property is used, it is considered that the valley of the sound absorbing property can be eliminated by changing the thickness of the sound absorbing layer in the track width direction.

FIG. 6 shows that the sound absorbing layer has a thickness of 40 to 100 mm.
7 is a graph showing sound absorption characteristics when the sound absorption characteristics are changed depending on the location in the range of FIG. As is apparent from the figure, the valley of the sound absorption characteristics is eliminated, and the sound absorption characteristics are extremely leveled and excellent sound absorption characteristics are obtained. From this, it can be seen that by appropriately changing the thickness of the sound absorbing layer on the track, good sound absorbing characteristics can be obtained.

[0026]

As is apparent from the above description, in the noise reduction type track structure of the present invention in which the sound absorbing layer thickness is changed, the sound absorbing characteristics of the portions having different layer thicknesses complement each other. The effect is that a sound absorbing layer showing good sound absorbing characteristics over a wide frequency band without any noise can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a noise reduction type track structure in which a thickness of a sound absorbing layer is changed according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the noise reduction type track structure of FIG.

FIG. 3 is a diagram showing a particle size distribution of a recycled material used to form a recycled material layer according to one embodiment of the present invention. The solid line indicates the particle size distribution of the recycled material, and the range indicated by hatching in the lower left direction is the single-particle crushed stone No. 7 (J
The range indicated by hatching in the lower right of the particle size distribution of IS A 5001) indicates the particle size distribution of crushed sand for concrete (JISA 5005) as a reference.

FIG. 4 is a graph showing sound absorption characteristics of a recycled material, a single-grained crushed stone No. 7, and a ballast ballast.

FIG. 5 is a graph showing a change in sound absorption characteristics when the spray thickness (layer thickness) of the recycled material is changed.

FIG. 6 is a graph showing sound absorption characteristics when the thickness of the sound absorbing layer is changed depending on the location within a range of 40 to 100 mm.

FIG. 7 is a cross-sectional view showing a track on which a conventional elastic material laying method has been applied.

FIG. 8 is a cross-sectional view showing a track on which a conventional sound absorbing material laying method is applied.

FIG. 9 is a view showing a track on which a conventional ballast laying method is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sound absorption layer 2 Track slab 3 Rail fastening stand 4 Side embankment 5 Rail 21 Rail 23 Track slab 25 Elastic material 27 Sound absorbing material 31 Track slab 33 Roadbed ballast 35 Depression

Continued on the front page (72) Keiichi Meien, 2-8-8 Hikaricho, Kokubunji-shi, Tokyo Inside the Railway Technical Research Institute (72) Inventor Yukio Hattori 5-1 Todorokicho, Inage-ku, Chiba-shi, Chiba −91− 201 (72) Inventor Mitsuo Yamamoto 52, Kasumigaoka, Nishi-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Kazuhiro Kudo 1-8-4, Dobashi, Miyamae-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Shinichi Iwamoto, Chiba-shi, Chiba-shi 8-7 Meet Shiomioka, Shiomioka-cho, Ward 404 (72) Inventor Masaru Kojima 1347 Noman, Ichihara-shi, Chiba (56) References JP-A-53-145816 (JP, A) Japanese Utility Model Application Hei 5-3304 (JP, U) 52-61008 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) E01B 1/00 E01B 19/00 C04B 38/00 303

Claims (2)

(57) [Claims] A track slab on which a rail is laid;
A sound-absorbing layer structure comprising a sound-absorbing layer laid on the track slab; wherein the sound-absorbing layer is made of a porous body having open cells in which particles are dispersed, and the thickness of the sound-absorbing layer is A noise-reducing track structure in which the thickness of the sound absorbing layer is changed, which differs in the width direction of the slab. 2. The particle diameter of the particles is 1 to 5 mm, and the surface of the sound absorbing layer has been subjected to particle scattering prevention treatment.
The noise reducing type track structure according to claim 1, wherein the thickness of the sound absorbing layer is changed.