JPH01275896A - Attenuating method for air pressure noise at tunnel exit - Google Patents

Abstract

PURPOSE:To attenuate the scale of a compressed wave generated when a train is rushed into a tunnel, by a simple and economical method, by arranging reflecting plates projected in the radial direction, on the internal wall surface of the tunnel, at proper intervals. CONSTITUTION:On the internal wall surface of a tunnel 11, radially projected reflecting plates 12 are arranged at proper intervals. A pressure wave generated when a train 14 or the like is rushed into the tunnel 11 is struck against the reflecting plates 12 in order, while the pressure wave is propagated in the tunnel 11 at a sound speed, and the wave is gradually attenuated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for attenuating compression waves generated when a train or the like enters a tunnel at high speed, and reducing air pressure noise at the exit side of the tunnel due to the compression waves. It is related to.

[Conventional technology]

Normally, when a train enters a tunnel at high speed, compression waves are generated at the tunnel entrance, propagate inside the tunnel at the speed of sound, and are radiated outside from the tunnel exit. When this compression wave is radiated from the tunnel exit side, it generates a plosive sound called a "tone" (pneumatic sound), and it also vibrates the windows and doors of nearby buildings, causing vibration noise. . The air pressure sound has a property that the larger the pressure gradient (size of the compression wave) in front of the wave front of the compression wave that reaches the tunnel exit side, the louder the sound becomes. Moreover, the pressure gradient in front of the wave front of the compression wave has a property that it is proportional to the cube of the speed V at which the train rushes into the tunnel.

Therefore, in the past, the air pressure noise generated at the tunnel exit side has been reduced by techniques such as those described in Japanese Patent Publication No. 55-31274 shown in No. 5FyJ and FIG. In other words, the technology shown in FIGS. 5 and 6 has an opening on the entrance side of the tunnel l, the size of the opening cross section is larger than that of the tunnel 1, and the length is 1 of the diameter of the tunnel l.
A cover 2 about 3 times larger is installed, and a window 3 having an optimum area determined from the cross-sectional area and length of the opening of the cover 2 is formed in the center of the side surface of the cover 2. As a result, train 4
By letting the negative part of the compression wave that is generated when it enters the tunnel 1 escape through the window 3 and making the pressure gradient in front of the compression wave gentle, the compression wave propagates inside the tunnel 1 at the speed of sound. This is to reduce the air pressure sound that occurs when it is radiated at the tunnel exit side.

[Problem to be solved by the invention]

By the way, in the conventional method, as mentioned above, the magnitude of the compression wave is proportional to the cube of the speed at which the train 4 enters the tunnel 1, so the speed of the train 4 is increased. However, in order to also reduce the loudness of the air pressure noise, the length of the cover 2 and the size of the window portion 3 are increased and changed in response to the increase in the rush speed of the train 4, and the cover 2 is increased. It is necessary to enhance the degree of compression wave reduction effect. However, depending on the location conditions such as the surrounding topography and track equipment, there are places where the cover 2 cannot be made longer, and in such places, the speed V of the train 4 entering the tunnel 1 must be reduced. , we had no choice but to give up on increasing train speed. Also, the speed V of the train 4 entering the tunnel 1 is set to, for example, 22 per hour.
In order to reduce the size of compression waves while ensuring a speed of 0 km/h or more, in the case of Shinkansen tunnels, coverings 2
The length is required to be around 16m. However, when constructing or expanding a new covering structure 2 of such length, civil engineering work, overhead contact lines, power line 2 communication lines, steel poles supporting these overhead lines, and other track incidental equipment must be moved or It is necessary to construct a new building, and the construction cost for that is more than worth it.2
The drawback was that it cost more than the construction cost of the Furthermore, unless the cover 2 is installed at both entrances of the tunnel 1, it will not have the effect of attenuating compression waves against the trains 4 coming from both directions, resulting in an enormous increase in construction costs.

[Means to solve the problem]

The present invention improves and eliminates the above drawbacks of the conventional technology, and provides a simple and inexpensive method for reducing the magnitude of compression waves generated when a train enters a tunnel. This is what I am trying to do.

Therefore, the means adopted by the present invention to solve the above problem is to arrange reflector plates projecting in the radial direction on the inner wall surface of the tunnel at appropriate intervals, so as to reduce the compression that occurs when a train or the like rushes into the tunnel. A portion of the wave collides with the reflecting plate to be reflected and disturbed, thereby attenuating the compression wave.

[For production]

When a train enters a tunnel at high speed, compression waves are generated. However, a portion of this compression wave collides with the reflection plates arranged at appropriate intervals on the tunnel inner wall surface, and is reflected, disturbed, and attenuated.The reflection plates are arranged at appropriate intervals on the tunnel inner wall surface. Therefore, while propagating at the speed of sound in the tunnel, the compression wave collides with these reflecting plates one after another and is gradually attenuated. Therefore, it is possible to reduce air pressure noise generated by compression waves radiated from the tunnel exit side.

〔Example〕

The method of the present invention will be explained below based on the embodiments shown in the drawings.

FIG. 1 is a vertical cross-sectional front view of a tunnel 11 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a reflecting plate 12. As shown in the figure, this reflecting plate 12 has an L-shaped cross section, a thickness of 9 m, and two vertically intersecting surfaces 12a, 1.
The width of both 2b is 200m, and the length is 2500 cranes. This reflecting plate 12 is provided with an L-shaped piece 12a on the left and right side walls of the inner wall surface of the tunnel 11.
are arranged to protrude in the radial direction of the tunnel 11 (in the illustrated embodiment, in a direction perpendicular to the railroad tracks), and are fixed with anchor bolts 13 or the like. Note that the reflectors 12 may be arranged at a predetermined pitch over the entire length of the tunnel 11, or may be arranged in a predetermined number only on the entrance or exit side of the tunnel 11. The reflective plates 12 may be disposed only in the center, and the pitch between the reflective plates 12 may be appropriately selected.

When a train 14 rushes at high speed into a tunnel 11 provided with such a reflecting plate 12, a compression wave is generated at the entrance side of the tunnel 11. As described above, this compression wave has a magnitude proportional to the cube of the speed at which the train 14 enters. However, a portion of the generated compression waves collides with the reflection plates 12 arranged at predetermined intervals on the inner wall surface of the tunnel 11, is reflected, disturbed, and attenuated.

Furthermore, since a large number of reflecting plates 12 are arranged at predetermined intervals, the magnitude of the compression waves is attenuated sequentially. Therefore, the compression wave propagating at the speed of sound in the tunnel 11 becomes extremely small in size (pressure gradient in front of the compression wave) while reaching the exit side of the tunnel 11. Therefore, the air pressure sound generated when the compression wave is radiated from the exit of the tunnel 11 is also reduced.

Figures 3 and 4 show that at the east exit of the Shinkansen Iwakuni Tunnel, which has a total length of 5132 m, reflectors 12 of the above-mentioned size and shape are installed at a pitch of 6 m over a length of 1500 m from the tunnel entrance. This is a characteristic diagram obtained by actually measuring and averaging the relationship between the inrush speed of the train 14 and the maximum value of the compression wave (pressure gradient in front of the compression wave). The characteristic drawing in Figure 3 is a result of measuring the maximum value of the compression wave on the east exit side when the train 14 enters the tunnel from the west exit, and the characteristic drawing in Figure 4 is the result of measuring the maximum value of the compression wave on the east exit side when the train 14 enters the tunnel from the east exit. The maximum value of the compression wave was measured at the west entrance when entering the tunnel.

According to the characteristic drawing shown in Fig. 3, train 14 is 220 km long.
When entering the west exit at an entry speed of /h, the maximum value of the compression wave at the east exit in the conventional case where the reflector 12 is not installed is 13
Kg/rrf, and the maximum value of the compression wave at the east exit when the reflector 12 was installed was 10 glrd.

Therefore, after installing the reflection plate 12, a compression wave attenuation effect of 3 kg1rd was obtained. Furthermore, according to the characteristic diagram shown in Fig. 4, when the train 14 enters the east exit at an entry speed of 220 m/h, the maximum value of the compression wave at the west exit in the conventional case where the reflector 12 is not installed. is 12Kg/n4, and the maximum value of the compression wave at the west exit after installing the reflector 12 is 9
Kg/rd. From this, after installing the reflector 12, a compression wave attenuation effect of 3 Kg/rd was also obtained on the west exit side.

What is clear from the above measurement results is that the installation position of the reflector 12 to obtain the effect of attenuating compression waves has nothing to do with the direction in which the train 14 enters the tunnel. If the reflector plate 12 is installed in a small area (on either side), such as near the west exit or in the center, it will be effective to sufficiently attenuate compression waves.

The present invention is not limited to the embodiments described above, and can be modified as appropriate. For example, the reflecting plates 12 (plurality) may be used alone, or the covering 2 (see FIG. 5) may be used alone. and Figure 6) is installed in tunnel 1,
It may also be used together with this cover 2. When the reflection plate 12 and the cover 2 are used together, it is possible to obtain a synergistic effect on the attenuation effect of compression waves. In addition, the size, shape, arrangement position, arrangement pitch, arrangement length, etc. of the reflector 12 are determined in consideration of the size of the tunnel 11, the speed at which the train 14 enters the tunnel 11, construction workability, etc. Just do it like this. Furthermore, the present invention can also be applied to tunnels of railways and other transportation means other than railways.

〔Effect of the invention〕

As explained above, in the present invention, by installing a reflecting plate on the inner wall surface of the tunnel, a part of the compression waves generated when a train rushes into the tunnel at high speed collides with the reflecting plate and is reflected. , it is possible to attenuate the magnitude of the compression wave and thereby reduce the pneumatic noise caused by the compression wave radiated from the tunnel exit. In addition, air pressure noise at the tunnel exit can be reduced by simply installing a reflector with a simple structure on the inner wall of the tunnel, so there is no need to move the track equipment, etc., and the construction work and costs are reduced. It is possible to significantly reduce the burden on Furthermore, there are no restrictions on the location conditions of tunnel entrances and exits, and moreover, it is possible to install it at any position within the tunnel. Therefore, there is no need to install it on both sides of the tunnel entrance, which is extremely convenient.

[Brief explanation of the drawing]

1 to 4 are related to the present invention, in which FIG. 1 is a vertical cross-sectional front view of the tunnel, FIG. 2 is a partial cross-sectional view of the tunnel showing how the reflector is attached, and FIG. Figure 4 is a drawing showing the relationship between the speed of a train entering a tunnel and the maximum value of compression waves, Figures 5 and 6 are related to the prior art, and Figure 5 is a diagram showing the relationship between the speed of a train entering a tunnel and the maximum value of compression waves. FIG. 6 is a side view of the installed case, and FIG. 6 is a longitudinal cross-sectional front view of the same part. 11...Tunnel 12...Reflector 14...
・Train patent applicant West Japan Railway Company Agent
Patent Attorney Toshihiko Uchida Figure 1 Figure 2

Claims (1)

[Claims] 1. Reflection plates protruding in the radial direction are arranged on the inner wall surface of the tunnel at appropriate intervals, and a part of the compression waves generated when a train or the like enters the tunnel collides with the reflection plates to be reflected and disturbed. A method for reducing air pressure noise at a tunnel exit, characterized by attenuating compression waves.