JPH10183539A - Sound absorbing structure for preventing traffic noise - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorbing structure which is effective in absorbing reflecting sound from a shielding plate on a road side, where inhabitants are suffered from traffic noise, and expected to largely contribute to improvement in living environment. SOLUTION: A sound absorbing structure is formed by combining a glass wool sound absorbing molded body 1 which is additionally fitted to a side wall where traffic noise is generated and formed by stacking a lot of sound absorbing semi-cylindrical boards 11 having semi-cylindrical section on horizontal axis in opposition to the propagating direction of the sound source, a waterproofing film 2 covering all the exposed face of the glass wool sound absorbing molding body 1, a frame internally fitted to both of the lass wool sound absorbing molded body 1 and the waterproofing film 2, and an auxiliary member 3 effective for improving other sound absorbing functions and strength. A part of noise is repeated collision and reflection in a hollow part between a cylindrical shape and a cylindrical shape so as to be converged and quenched, on the contrary, the residual noise is diffused to the outside and rapidly lost its energy, and the combination of both actions can thus solve the issue.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road traffic, that is, a general road, a highway, or a two-story road having a highway at an upper part and a general road at a lower part thereof, a bridge for a railway or a car, an excavation road, and the like. Pertains to sound absorbers that focus on noise prevention in tunnels and the like.

[0002]

2. Description of the Related Art The noise of road traffic has long been discussed as a social problem, but the use of land is extremely severe, especially in urban areas, and how to use limited land effectively. This is a very big proposition. On the other hand, the problem of traffic noise generated from expressways and general roads has seriously degraded the living environment of residents around the roads due to the increase in the size and speed of passing vehicles. As the speed increases far beyond the accepted noise levels, conflicts often arise with residents as new challenges. Actually JR
Express trains from West Japan and the Nankai Railway bound for Kansai Airport are subject to a new noise dispute among residents along the line.

[0003] As a typical example conventionally planned and executed with the greatest purpose of effective use of land, a congested road in an urban area is constructed at once by constructing an excavated road and using the upper part as a general road or a residential area. Measures are being taken to mitigate this. However, this configuration immediately resulted in the doubling of noise pollution to nearby residents, and many countermeasures have been proposed and put into practice to control the pollution.

[0004] For example, in order to reduce the influence of the surrounding residents on the excavation road in the city center as much as possible, as shown in FIG. And a soundproof wall 104 is also provided upright on the side wall of the upper general road 103 to block the propagation of sound generated when the vehicle passes by the side surface so as not to diffuse to the surroundings. In this case, it is also pointed out that noise generated from a general road enters the excavation side wall and is reflected, and the reflected wave directly hits a house or the like around the road through the soundproof wall 104. There are many conventional techniques for absorbing noise energy by absorbing a reflected wave from the back surface.

[0005] There is a sound absorbing cylinder type as a type which is relatively frequently applied. In the prior art disclosed in Japanese Patent Laid-Open No. 7-82708 shown in FIG.
Are covered with a waterproof film 106, and a number of sound absorbing cylinders whose outer periphery is protected by a punching metal 107 are arranged. A configuration in which a gap 108 is provided between at least the lower half waterproof film 106 and the punching metal 107 of these sound absorbing cylinders is presented, and rainwater that has entered the sound absorbing cylinder easily escapes from the punching metal to prevent corrosion of the punching metal. It also states that the waterproof film and the perforated metal are in point contact with each other, so that free vibration of the waterproof film is not hindered.

Japanese Unexamined Utility Model Publication No. 2-333812 discloses a noise prevention structure provided at the lower part of a viaduct girder. This structure has a structure in which a substrate made of a girder selected from steel, concrete or the like and a porous sound absorbing material are fixed. It proposes a structure provided with a space.

In JP-A-53-92519, as shown in FIG. 9, a sound absorbing material 110 such as glass wool is provided on the sound source side of a corrugated plate 109, and a sound insulating plate 11 such as a metal plate is provided on the opposite side.
1 shows a soundproof panel configured as a sandwich-type panel.

The prior art disclosed in Japanese Patent Application Laid-Open No. 54-99401 has a structure in which grooves are arranged linearly and parallel to each other on a plane so as to attenuate the sound field, and ribs are provided between the grooves. The surface of the sound-absorbing structure should be approximately parallel to the direction of propagation of the sound field to be attenuated, indicating the body and creating an acoustic coupling between adjacent grooves at the frequency to be attenuated It is characterized by. This prior art employs the principle of the Helmholtz resonator, which is already known, which is provided with a device which, when passing through a special wall, reduces transmission and reduces reverberation in an adjacent room. It is. In any case, this prior art has the greatest feature in that adjacent acoustic couplings occur, and it is recognized that focusing on a specific frequency is effective for attenuation of acoustic energy. Can be

[0009]

As described above, the prior art for presenting a sound absorbing structure for the purpose of preventing and suppressing traffic noise is so diverse that there is no time to enumerate it. I have to say that it is far from being an all-purpose. The first difficulty is that when the target is an ordinary road, the passing vehicles do not show a particularly prominent tendency, from large trucks and buses with large capacity diesel engines, to ordinary vehicles, and finally to motorcycles and scooters. Even light vehicles vary widely, and the frequency of the sound emitted during driving also has a remarkable difference in length.
Since a wide range of 00 Hz is a well-documented theory that has been recorded in conventional on-site measurements, it is assumed that the coupling phenomenon is derived by narrowing down to a specific sound range (frequency) as in one of the above-mentioned prior arts. Even if the energy is consumed, it is difficult to understand that it works very effectively in other sound ranges, so it is hard to judge that it is an effective solution if it is evaluated only for measures against noise of general vehicles.

[0010] The underside of an elevated road, a general road,
The sound absorbing structure provided along the excavation road and the side wall of the tunnel is not a fixed direction, constant frequency sound generated at the position where it is stopped, but from various angles from the sound source moving on the general road to the side wall. It consists of complex elements that approach rapidly while transmitting, and when measuring the ability to absorb the wave from a static sound source in an enclosed space, ignoring the condition that it does not match the actual feeling of hearing to the human body Not be. At least conventional measurement values as indicators such as "normal incidence sound absorption coefficient" or "reverberation chamber sound absorption coefficient" do not include the special condition of almost constant angle from the traveling direction of the vehicle, so the actual sound There is a divergence between the input and the reflection. Today, a sound absorbing plate 113 having a fixed area is laid on the rigid floor surface of the simple anechoic chamber 112 as shown in FIG. 10 in order to approximate the sound actually felt by the human body and its sound absorbing effect as much as possible. A method is adopted in which sound is emitted from the speaker 114 from each direction of 15 °, 30 °, and 45 °, and the sound is received by the microphone 115 on the other side to evaluate the sound absorbing ability at each angle.

As described above, there are many prior arts, each of which is not necessarily ineffective. However, at least absorbing traffic noise means that noise and vibration generated constantly from a fixed point of ordinary machinery and equipment. A more complicated element is added than the soundproofing equipment for the above, etc., and it is not considered that a single wave, which has already been quoted as a few, has the effect of absorbing a straight wave in a completely effective manner. Thus, only a simple sound absorbing effect that the absorbed wave energy is all can be generated, and there is no great expectation for the attenuation of the complicated noise mixed in long and short.

In order to solve the above-mentioned problems, the present invention is particularly effective for absorbing sound reflected from a shielding plate around a roadside, which is troubled by traffic noise, and is expected to greatly contribute to improvement of living environment. The purpose is to provide.

[0013]

SUMMARY OF THE INVENTION A side wall sound absorbing structure for preventing traffic noise according to the present invention is used to prevent noise generated in vehicle traffic on roads, piers, tunnels, roadside buildings, plants and the like. A glass wool sound-absorbing molded body 1 formed by stacking a number of axes in a horizontal direction on a sound absorbing semi-cylindrical plate 11 having a semi-cylindrical cross section opposed to the direction of noise propagation. A waterproof film 2 covering all exposed surfaces of the glass wool sound absorbing molded article 1
The structure is characterized in that the glass wool sound-absorbing molded article 1 and the waterproof film 2 are combined together with a frame in which the molded article and the auxiliary member 3 effective for improving the sound absorbing function and strength are formed.

Conventionally, the main components such as a sound absorbing plate for noise use a glass wool and a waterproof film that shields the surface of the wool so as not to be wet, which is a typical constituent material which is often followed in the prior art. This is an essential basic component based on the two points that noise countermeasures must be installed outdoors and that glass wool has extremely high water absorption and contains water, which immediately deteriorates the sound absorption effect. It becomes. On the other hand, it is known that the thinner the thickness of the waterproof film, the less the sound absorption coefficient is impaired. In particular, when the frequency exceeds 1 KHz, it extremely decreases. For example, glass wool having a thickness of 32 kg / cm ³ and 100 mm thickness is reduced to 4 KHz. 21μm when facing a sound wave of the frequency
Comparing the case with and without the waterproof film
Experimental records indicate that the sound absorption coefficient is reduced by as much as 0%.

The gist of the present invention lies in how to exhibit an efficient sound absorbing function while using the constituent materials which have been almost commonly used in this prior art as well. I have no choice but to wait for future experiments and analyses. However, what can be estimated at this point is that FIG.
As indicated symbolically by, in the vicinity between the dotted lines,
Waves incident at a certain angle into the gap S between the arcs formed by a large number of anti-cylindrical surfaces travel while repeating collision and reflection in the gap, and absorb most of the stored energy. Is done. In the vicinity of the area between the dotted line and the dashed line, the first reflection occurs on the semi-cylindrical surface, and then the second reflection occurs on the neighboring semi-cylindrical surface. Go back to. Note that only the first-stage sound absorption and reflection occur in the range surrounded by the dashed line. What can be said as a whole is that the sound incident on the cylindrical surface with directionality is absorbed, scattered and reflected,
The sound of high energy is returned dispersed in all directions, and only low energy returns in the direction of the sound source. When half of the energy is absorbed when noise is incident, the remaining half is reflected, but when the reflected sound is further reflected, one-fourth energy is absorbed and one-quarter energy is reflected. You. When reflected three times, 1 /
Only 8 energies will be reflected. Therefore, any sound wave of any frequency is caught in the stenotic waveform gap and continues to scatter and collide, and disappears.
It can be determined that all of the mixed noises of various frequencies are efficiently consumed.

On the other hand, the wave confined in the gap S is specified by an incident angle that maintains a constant angle with respect to the circumferential surface, but there is naturally a wave incident at an elevation angle larger than the specified angle. In addition, there may be a wave that collides with the surface near the center of the cylindrical surface that has deviated from the gap S. Since these waves are diffused by 360 ° with respect to the outside world, diametrically opposite to the converging waves, as shown symbolically in FIG. It is inferred that energy is lost in inverse proportion to the square. By properly setting the gap S in this way,
In other words, if the curvature of a semi-cylindrical section is set appropriately, and the relevance to the angle of incidence of the noise is continued in more detail, most of the noise will collide and reflect in the gap between the cylinders. Can be interpreted as converging and disappearing, and the remaining noise can be interpreted as spreading to the outside and rapidly losing power.
Both actions solve the problem together.

The auxiliary member 3 supporting the above-mentioned basic structure includes a punched metal 31 made of aluminum facing the direction of noise propagation, a glass cloth 32 adhered to the bottom surface of the punched metal 31 made of aluminum, and fitted inside the two members. One typical assembly method comprises a frame 33 for mounting the glass wool sound-absorbing molded body 1 at a predetermined position and / or a sound insulating plate 34 for fixing the glass wool sound-absorbing molded body 1 at a mounting position. It goes without saying that the gist of the invention is not limited.

Finally, from the requirements of the present invention described above, the greatest advantage is that it is possible to cope with noise mixed with any frequency, but as a result of noise measurement, it is possible to detect the frequency of noise that is particularly noticeable along the road. In some cases.
For example, in the case of passing noise such as the above-mentioned conventional line limited express or Shinkansen, a specific wavelength should be mainly understood,
Despite the gist of the present invention, it is more efficient if the wavelength is incorporated into the design elements and reflected in the selection of the curvature of the cylindrical radius, the height to be attached to the side wall, the gap between the cylindrical shapes, and sometimes the inclination angle. There is also an expectation that appropriate responses will be utilized.

[0019]

1 (A) and 1 (B) show one embodiment of the present invention. FIG. 1 (A) is a longitudinal sectional front view in which a glass wool sound-absorbing molded article 1 is fitted into an auxiliary member, and FIG. It is a side view (B) attached to the side wall W of a sound insulation board etc. The glass wool sound-absorbing molded body has a large number of sound-absorbing semi-cylindrical plates 11 in a state where their axes are arranged horizontally, and the front, back and side surfaces thereof are all adhered and covered with a waterproof film 2, and the wave which directly hits the surface of the sound absorbing half-cylindrical plates By vibrating the waterproof film 2, the fiber of the glass wool is vibrated, and its energy is replaced and consumed.

In order to form a sound-absorbing structure mainly composed of a glass wool sound-absorbing molded body, it is necessary to combine it with other auxiliary members in order to be able to exhibit its function sufficiently and to be installed outdoors where vibrations or the like are severe. FIG. 2 is an exploded perspective view of a procedure for assembling the structure mainly using the glass wool sound-absorbing molded body 1, which is disassembled into stages (A) to (E) for convenience of understanding. The lower part of the figure faces the sound source side, that is, the road for general vehicles, and the upper part is the side wall side, that is, the portion attached to the side wall surface to be attached. The structure is made of a punching material 31 made of aluminum or stainless steel from the bottom in consideration of the rustproof surface, and a glass cloth 32 is provided along the bottom surface of the frame 35 having a perforated plate only on the bottom surface so as not to hinder the sound absorbing effect. The glass wool sound-absorbing molded body 1 covered with the waterproof film 2 is fitted thereon.
The thinner the thickness of the waterproofing film, the lesser the requirement for inhibiting the sound absorbing effect. However, if the film is broken, rainwater or dust may enter the waterproofing film. The perforated metal containing the glass cloth, the glass wool sound-absorbing molded product, and the waterproof film is fitted into the frame body 33 assembled with a lip channel steel or the like so that the glass wool sound-absorbing molded material, which is a main part, is not damaged even when external force is applied. The sound insulating plate 34 made of a galvanized steel plate or a deck plate is further covered on the top surface, and is fixed to a mounting member attached to concrete on the side wall surface of the sound insulating plate or a steel frame material. The form of the structure to which the glass wool sound-absorbing molded body is attached is as shown in FIG. 1B, and the side walls erected along general roads, highways, excavation roads, piers, railway tracks, tunnels, roadside buildings, and the like. Even if they are installed side by side on the surface of the city, they should not be unsightly forms that would impair the aesthetics of the surrounding city, and should be evaluated for their outstanding action and for maintaining the familiar form of the cityscape .

A comparison of the sound absorption coefficient between the prior art and the present invention demonstrates one of the effects of the present invention. According to Kobayashi Riken, a company that has been measuring and investigating traffic noise for many years,
Since the reliability of the measured values of 15 Hz or less has a doubt and the dispersion is large, the range of 400 Hz or more is evaluated. The energy of traffic noise in the range of 400 to 4000 Hz is about 9% of the noise level of 125 to 4000 Hz.
It is said to account for 3%. The oblique incidence sound absorption coefficient means the sound absorption coefficient at each angle of 0 °, 15 °, 30 °, and 45 °, and dividing by 4 in addition to the front part gives the average oblique incidence sound absorption coefficient. The frequency of road traffic noise is 400-4000Hz
But a coefficient (weighting coefficient) for the angular frequency for each angle
To display the sound absorption coefficient.

FIG. 4 shows a comparative example 1 of the prior art, in which the form of the sound absorbing plate is such that one glass wool plate having a thickness of 100 mm is arranged on the rigid floor of the simple anechoic chamber as shown in FIG. did.
The angle between the speaker as the sound source and the microphone of the reflected sound is varied to 0 °, 15 °, 30 °, and 45 °, and the frequency of the sound wave is 400 to occupy the main part of the road noise.
The sound absorption coefficient at each angle and each frequency was measured with the frequency limited to 4000 Hz, and plotted in FIG. As a result, the average oblique incidence sound absorption coefficient according to the prior art of only one glass wool plate was 0.86.

FIG. 5 shows a comparative example 2 measured by another conventional technique, in which a 50 mm-thick air layer is formed between the glass wool plate and the floor surface under a 50 mm-thick glass wool plate. The rate was measured. As a result, as shown in FIG. 5B, the average oblique incidence sound absorption coefficient is 0.82, which is lower than that of Comparative Example 1.
As shown in the chart, the sound absorption coefficients at 1000 Hz and 2500 Hz are remarkably low, and there is a question as to whether the sound wave generated by the vehicle can cope with the main wavelength in practical use.

FIG. 6 shows an embodiment of the present invention.
This is an embodiment in which a glass wool plate of mm is formed into a semi-cylindrical shape and arranged in parallel with each other. As shown in FIG. 6B, the sound absorption coefficient is uniformly improved as a whole, and the average oblique incident sound absorption coefficient is 0.8.
A numerical value of 9 is recorded, indicating that the gist of the present invention is correct and superior to other prior art levels.

[0025]

As described above, the present invention has an excellent sound absorbing effect as compared with the prior art, and has been working hard on general roads under elevated tracks, excavated roads, piers, tunnels, and the like. This provides an effect that a more effective means for preventing traffic noise can be provided. As a result, it can be expected to exert a considerable power to absorb traffic noise, which has been a root cause of disasters in the neighborhood such as roads and railway tracks, and to solve social problems. Moreover, there are many advantages such as not being difficult to install, the scenery after installation does not impair the beauty of the urban area, it is functional, the structure is simple, and it is economically advantageous . In recent years, the problem of noise pollution has frequently been repelled by severe residents who cannot even maintain urban planning, and generalized rational solutions that meet physical laws as in the present invention have been further developed. We want to expect promotion of town building that we did.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view (A) and a side view (B) of an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the assembly according to the present invention and shown in (A) to (E).

FIG. 3 is a schematic vertical sectional front view showing two functions of the present invention in (A) and (B).

FIG. 4 shows the experimental form (A) and the oblique incidence sound absorption coefficient (B) for each frequency of the prior art (Comparative Example 1).

FIG. 5 shows an experimental form (A) and an oblique incidence sound absorption coefficient (B) for each frequency of the conventional technique (Comparative Example 2).

FIG. 6 is a diagram (B) of the configuration (A) of the embodiment of the present invention and the oblique incidence sound absorption coefficient by frequency.

FIG. 7 is a longitudinal side view showing a direction of noise propagation on an excavation road.

FIG. 8 is a sectional view of a conventional sound absorbing cylinder.

FIG. 9 is a longitudinal sectional front view (A) and a plan view (B) of another conventional technique.

FIG. 10 is a schematic sectional view showing a structure of a simple anechoic chamber.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass wool sound absorption molded object 2 Waterproof film 3 Auxiliary member 11 Sound absorption semi-cylindrical plate 31 Aluminum perforated metal 32 Glass cloth 33 Frame 34 Sound insulation plate

Claims (2)

[Claims] 1. A sound absorbing structure mounted along a side wall of a noise source for preventing noise generated in a vehicle traffic such as a road, a bridge, a tunnel, etc., having a semi-cylindrical cross section facing a noise propagation direction. A glass wool sound-absorbing molded body 1 formed by stacking a number of sound absorbing semi-cylindrical plates 11 in the horizontal direction, a waterproof film 2 covering all exposed surfaces of the glass wool sound-absorbing molded body 1, and a glass wool sound-absorbing molded body 1
A sound absorbing structure for preventing traffic noise, which is formed by combining a frame and an auxiliary member 3 effective for improving the sound absorbing function and strength together with the frame and the waterproof film 2. 2. The punching material 31 according to claim 1, wherein the auxiliary member 3 uses a rust preventive material such as aluminum or stainless steel plate facing the noise propagation direction, a glass cloth 32 attached to the bottom surface of the punching material 31, A sound absorbing structure for preventing traffic noise, comprising: a frame 33 for mounting the glass wool sound-absorbing molded article 1 covered with a waterproof film internally fitted to the two members on a predetermined side wall; and a sound insulating plate 34 fixed to the side wall. body.