JPH09273123A - Sound insulating wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the sound insulating effect without extending up a sound insulating wall, by providing an inclined wall and branched walls at the upper end of the vertically erected wall, in order to reduce noise brought from roads, railroads, factories, etc. SOLUTION: An inclined wall 2 is provided at the upper end of a vertically erected wall 1 as a soundproof wall to attenuate noise generated in trains T. And branched walls 3, 4 are provided at the ends of the inclined wall 2 and the vertically erected wall 1. And a sound absorbing material is attached to respective wall faces. Noise A of a current collector for pantographs or stringing is reflected by the inclined wall and intensified to turn upward and sound waves going over the branched wall 3 are attenuated owing to the diffraction. Noise B of the rotary moving of wheels rises along the vertically erected wall 1 and it is intensified to turn upward at the front end of the branched wall 4 and the sound waves going over the front end of the branched wall are reflected by the branched wall 3 and attenuated owing to the interference with other sound waves and further, intensified to turn upward because of the resonance between the branched walls 3, 4. Accordingly, the attenuating effect of noise can be improved without extending up the sound insulating wall.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soundproof wall provided for reducing noise generated from roads, railways, factories and the like.

[0002]

2. Description of the Related Art Conventionally, as a measure for preventing noise generated from roads, railways, factories, etc., it has been widely adopted to install a soundproof wall in order to prevent the noise from being propagated directly from the noise source. ing. This is because sound barriers are relatively inexpensive in various noise prevention measures, and are effective for various noise sources. In order to increase the noise reduction effect, it is necessary to increase the height of the soundproof wall. However, if the soundproof wall is made higher, the cost increases (the higher the height, the higher the construction cost and the like, and the higher the cost). In addition, there are many problems such as sunshine, landscape, view, feeling of oppression, ventilation, radio interference, and wind load resistance.

Further, if the noise reduction effect is not sufficient with the straight wall alone, the front end of the soundproof wall or the front end of the soundproof wall formed by bending the front end of the soundproof wall toward the noise source side in a shape of "<" is used. There are curved soundproof walls that are curved on the noise source side, but these are more problematic than straight walls.

With the recent increase in traffic and the speed of vehicles,
As the environmental noise problem becomes serious and there is no other countermeasure, at the expense of the above-mentioned problems, a straight-walled sound-insulating wall having a height of 5 m, 7 m, 10 m, a bent sound-insulating wall, and a curved sound-insulating wall Walls are used.

However, even if these soundproof walls are used, they can only be expected to have an effect corresponding to the height of the soundproof walls. Generally, at a distant position (at a distance of about 20 m from the soundproof wall), the noise reduction effect obtained by increasing the height of the soundproof wall by 1 m is about 1 dB.

At present, these straight walls and curved soundproof walls do not have a sufficient soundproofing effect because of a large amount of (diffraction) sound circling around the walls.

[0007] In the case of a railway vehicle, noise (upper noise) of the current collecting system due to the pantograph and overhead lines is generated, but some of this upper noise travels along the soundproof wall from the track floor surface by experiments and the like. It has been elucidated.

FIG. 21 shows an example of noise prevention of a conventional railway vehicle 100. The height of a soundproof wall (upright wall) 101 is 2 m, and the distance from the soundproof wall 101 to the railway track is 2 m.
The noise generation source of the railway vehicle 100 is set at a height of 1 m from the track surface. FIG. 22 shows the result of calculation of the sound energy flow (sound intensity) in the octave band of 250 Hz with respect to an upright wall using the boundary element method based on this conventional soundproofing measure.

[0009]

From the results shown in FIG. 22, it can be seen that the sound traveling along the soundproof wall passes through the soundproof wall and is transmitted as a sound with large energy. The direction of the arrow in the figure indicates the direction of the flow of sound energy, and the longer the length of the arrow, the higher the sound energy.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a soundproof wall which effectively prevents the sound traveling around the soundproof wall and can obtain a high soundproof effect without increasing the height of the wall. .

[0011]

In order to achieve the above-mentioned object, the present invention provides an inclined wall inclined to the side opposite to the sound source on the upper end of the upright wall, and the upper end of the upright wall and the upper end of the inclined wall on the sound source side. The first and second re-branching walls are provided in the opposite direction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a soundproof wall provided to prevent noise generated by the railroad vehicle T. An upright wall 1 is provided with an inclined wall 2 inclined toward the side opposite to the sound source, and the upright wall 1 is inclined at the upper end and the upright wall. First and second re-branching walls 3 and 4 are provided at the upper end of the wall 2 toward the sound source side. These upright wall 1, inclined wall 2, first
A sound absorbing material may be attached to the inside and / or the outside of the second re-branching walls 3 and 4. Rock wool, glass wool, ceramics, foam concrete, or the like can be used as the sound absorbing material. The sound absorbing material is attached by a bolt, a pin, an adhesive, a perforated plate, a wire mesh, etc. according to the material and the like.

FIG. 2 shows only the soundproof wall, and the total height is 2320.
mm, the height L ₁ and 1310mm upstanding wall 1, 210 mm horizontal length from the proximal end of the first re-branch wall 3 to the drawing on the right hand direction from the upright wall 1 of the second re-branch wall 4 And The re-branching walls 3 and 4 are provided so as to be perpendicular to the inclined wall 2 and face the sound source side. The height H of the inclined wall 2 of length L ₂ and re-branch wall 3, 4 interference described later in accordance with the frequency of the driving noise of the vehicle is determined so as to obtain a resonance effect efficiently.

These upright wall 1, inclined wall 2 and re-branching walls 3, 4 are made of concrete, slate, plastic,
The upright wall 1 is formed of a material having a sound insulating property such as a steel plate or an aluminum plate.
The unit may be fixed by bolts,
The upright wall 1, the inclined wall 2, and the re-branching walls 3 and 4 may all be integrally formed.

As described above, in an elevated railway surrounded by soundproof walls, the noise sources of the pantograph and overhead line current collection system (upper noise), vehicle rolling noise (lower noise), and aerodynamic noise are the main noise sources. . As shown in FIG. 1, these sounds include a sound A that is directly transmitted to the soundproof wall and a sound B that travels from the track floor surface along the inner surface of the soundproof wall.

The sound reduction effect of the sound wave B will be described below. The sound wave traveling along the inner surface of the soundproof wall is converted into a flow as shown in FIG. 3 at the tip of the re-branching wall 4. First, the sound wave B becomes a sound wave whose directivity is strengthened upward at the tip of the re-branching wall 4 like a path. Further, part of the light is diffracted at the tip of the re-branching wall 4 and is transmitted in the lateral direction. The sound waves directed in the lateral direction as described above are taken into the space surrounded by the re-branching walls 3 and 4 and the inclined wall 2. These sound waves are reflected by the re-branching wall 3 and are transmitted directly thereafter as shown in FIG.
'And the sound waves are attenuated by interfering with each other. This phenomenon occurs at many frequencies, but sound reduction can be effectively achieved at relatively low frequencies. Also, 15 for the inclined wall 2
It has also been confirmed by experiments by the present inventor that the sound reduction effect is high with respect to sound waves input at an angle of ° (see FIG. 5).

Further, the sound wave taken in the space surrounded by the re-branching walls 3 and 4 and the inclined wall 2 is repeatedly reflected between the re-branching walls 3 and 4, and the wavelength of the sound wave and the re-branching walls 3 and 4 are increased. If the spacing is properly configured, resonances as shown in Figure 6 will occur.
At this time, when attention is paid to a place where the sound pressure level of the resonant sound wave is high, there are waves traveling in the a direction and waves traveling in the b direction, as shown in FIG. At this time, as is well known in Huygens' principle, the sound wave generated from one sound source diffuses and travels while creating a new wavefront. The opposing sound waves' cancel each other out, as shown in FIG. 8, and the'and the sound waves vertically combined with the inclined wall 2 as shown in FIG. Also, the sound wave 'is reflected by the inclined wall.

Further, as shown in FIG. 10, a sound wave traveling on the inclined wall without being taken into the space surrounded by the re-branching walls 3 and 4 and the inclined wall 2 is combined with a sound wave 'directed upward by resonance. Therefore, the sound waves that have not been captured in the space surrounded by the re-branching walls 3 and 4 and the slanted walls can also be enhanced in upward directivity.

As described above, due to the resonance phenomenon, the directivity of the sound wave is strong upward and weak in the lateral direction, so that the sound transmitted over the soundproof wall is reduced.

Further, as shown in FIG. 11, a point S'combined with the sound wave (A) traveling along the inclined wall and the sound wave (B) traveling without being taken into the soundproof wall is generated again, as shown in FIG. And the sound waves are attenuated.

Explaining the sound reduction effect on the sound wave A, as shown in FIG. 12, among the noises (upper noise) of the current collecting system of the pantograph and the overhead line, the sound wave directly incident on the inclined wall is reflected by the inclined wall. As a result, the upward directivity is strengthened. Further, as shown in FIG. 13, the sound wave that goes over the re-branching wall 3 is weakened in energy by being diffracted again at the tip of the re-branching wall 3, and is transmitted.

FIG. 14 shows a soundproof wall of the present invention 250.
The results of simulating the energy flow of sound in the Hz octave band are shown (this simulation is the result of calculation only for sound waves traveling along the sound barrier). As is clear from this figure, the sound waves traveling along the inner surface of the soundproof wall are strengthened in directivity upward by the re-branching wall 4, and the space surrounded by the re-branching walls 3 and 4 and the inclined wall 2 is also increased. It is also understood that the sound waves are directed upward in that region, and as a result, in the soundproof wall of the present invention, the directivity is strongly upward and weakened in the lateral direction, so that the sound waves transmitted over the soundproof wall are attenuated.

In the embodiment shown in FIG. 15, a small wall 5 having an arbitrary height is provided between the re-branching walls 3 and 4, and the small wall 5 may be two or more.

In the embodiment shown in FIG. 16, both ends of the inclined wall 2 are extended.

Next, when the inclination angle of the inclined wall 2 with respect to the upright wall 1 is 0 ° (when the inclined wall 2 extends straight upward on the upright wall 1), 15 °, 30 °, 45 °, 60 °. Reduced volume (dB) compared to the case of conventional upright walls only
Is shown in the table below.

[0027]

[Table 1]

FIG. 17 shows the sound reduction effect of each of the embodiments shown in FIGS. 1 and 2 of the present invention and the case of the conventional straight wall only. The vertical axis represents the sound volume reduction (dB) and the horizontal axis represents the frequency (Hz), indicating that the damping effect of the present invention is high over almost the entire area. This data was obtained by simulating under the conditions shown in FIG.

FIGS. 19 and 20 show the present invention and the simulation results showing the sound pressure level (dB) around the straight wall, showing that the present invention transmits less sound over the wall.

[0030]

As described above, according to the present invention, the noise reduction effect is significantly improved without increasing the height of the soundproof wall.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a preferred embodiment of the present invention.

FIG. 2 is a side view showing only the soundproof wall.

FIG. 3 is an explanatory diagram of a flow of a sound wave B.

FIG. 4 is an explanatory view of the action of the sound wave B between the re-branching walls.

FIG. 5 is an explanatory diagram of an incident angle of a sound wave.

FIG. 6 is a diagram illustrating resonance.

FIG. 7 is an explanatory diagram of a place where a sound pressure level of a resonance sound wave is high.

FIG. 8 is an explanatory diagram of synthesized sound waves.

FIG. 9 is an explanatory diagram of a composite wave.

FIG. 10 is an explanatory diagram of sound waves that have not been captured by the re-branching wall.

FIG. 11 is an explanatory diagram of sound waves (A) and (B).

FIG. 12 is an explanatory diagram of a flow of a sound wave A.

FIG. 13 is an explanatory diagram of a sound wave that rides over a re-branching wall.

FIG. 14 is a diagram showing a flow of sound energy in a 250 Hz octave band.

FIG. 15 is a side view showing another embodiment.

FIG. 16 is a side view showing still another embodiment.

FIG. 17 is a graph showing the volume reduction.

FIG. 18 is a diagram showing a simulation method.

FIG. 19 is a distribution diagram of simulation results showing sound pressure levels.

20 is a distribution chart similar to FIG.

FIG. 21 is a diagram showing a conventional example.

FIG. 22 is a diagram showing a conventional sound energy flow around a straight wall.

[Explanation of symbols]

 1 Upright wall 2 Inclined wall 3 First re-branching wall 4 Second re-branching wall

Claims (1)

[Claims] 1. An upright wall is provided with an inclined wall that is inclined to the side opposite to the sound source, and first and second re-branching walls are provided toward the sound source side at the upper edge of the upright wall and the upper edge of the inclined wall. A soundproof wall characterized by that.