JP6261942B2 - Tunnel low frequency sound reduction device - Google Patents

Description

  The present invention relates to a tunnel low-frequency sound reduction device that is installed between a low-frequency sound generation source in a tunnel mine and a tunnel pit to reduce low-frequency sound that propagates from the low-frequency sound generation source to the tunnel pit.

  In recent years, in the construction site of a mountain tunnel, in order to prevent the noise inside the tunnel from leaking out as it is, a partition wall is often installed in the vicinity of the wellhead. The partition wall has a shape and a size that block the entire cross section of the tunnel, and a part of the partition wall is a soundproof door so that vehicles and workers can pass through. Such partition walls are often made of steel and are effective in blocking high-frequency sounds such as metal sounds, but have a low sound-insulating effect against low-frequency sounds such as blasting sounds. Therefore, at the mountain tunnel construction site where blasting work is performed, in order to prevent low-frequency blasting sound from leaking out of the tunnel as it is, the partition walls are made of concrete or doubled and sand is sandwiched between them. In some cases, the low-frequency sound was cut off by filling the bulkhead and making the partition bulky.

  However, even with such a heavy partition, since the soundproofing effect against low frequency sound is insufficient, various techniques for reducing rather than blocking the low frequency sound have been proposed. For example, tunnel blasting or tunnels closed with a predetermined partition, tunnel blasting in which a plurality of pipes with different path lengths are opened at one end and closed at the other end and are installed closer to the face than the predetermined partition A sound silencer has been proposed (see Patent Document 1). In this silencer, the path length of the pipe is set to 1/4 wavelength of the low frequency sound to be silenced, so that the sound wave that enters the pipe returns to the tunnel tunnel with a half wavelength phase delay, The sound waves cancel each other and mute each other.

  Also, a duct installed in the tunnel mine substantially parallel to the tunnel axis direction and having a large number of through holes in the circumferential surface defining a passage toward the tunnel axis direction, and a tunnel axis direction around each opening at both ends of the duct. There has been proposed a tunnel silencer that is installed at a substantially right angle and includes two partition walls that close the hollow cross section inside the tunnel outside the duct (see Patent Document 2). This silencer absorbs the noise generated on the face side in a resonant manner by the action of a large number of through holes on the peripheral surface of the duct and the closed cavity around the duct.

JP 2011-256609 A JP 2012-177221 A

  However, in the tunnel blasting silencer of Patent Document 1, a dedicated space is required to install the tube, and this space becomes a dead space. Moreover, the adjustment of the silencing performance performed by installing / removing the tube and changing the path length of the tube, that is, the frequency adjustment of the sound to be silenced is complicated. On the other hand, in the tunnel silencer of patent document 2, since a duct part becomes a narrow part and ensuring of a pedestrian passage is difficult, it is unpreferable on safety. Moreover, since it is difficult to change the dimensions of the duct or the through hole, the frequency of the sound to be silenced cannot be adjusted.

  The present invention has been made in view of such a background, and it is intended to provide a tunnel low-frequency sound reduction device that can easily secure a pedestrian passage and can easily perform installation / removal work and frequency adjustment of a reduction target sound. Main purpose.

  Such a problem is a tunnel low-frequency sound reduction device that is installed between a low-frequency sound source in a tunnel pit and a tunnel pit and reduces low-frequency sound that propagates from the low-frequency sound source to the tunnel pit ( 10), and the panel row (11) erected along the tunnel axis direction and the panel row (11) so as to close the space (5R, 5L) on one surface side of the panel row (11). Of the first partition wall (12) and the second partition wall (13) installed at both ends in the tunnel axis direction, and the panel row (11) is disposed at a predetermined interval in the tunnel axis direction. A space (5R, 5L) on the one surface side of the panel row and the other surface side through a slit (22) formed by a plurality of panel units (21) and formed between adjacent panel units (21). Space (5C) It is accomplished by providing a by which tunnel the low-frequency sound reduction device through.

  According to the present invention, the space on the other surface serves as a low-frequency sound propagation path, and the space on the one surface communicating with the space on the other surface via the slit serves as the resonance space. The low frequency sound to be reduced can be reduced by the resonance sound absorbing action between the space on one side and the slit. And by providing a door in the 1st partition, a pedestrian passage can be easily secured using the space of one side. Furthermore, panel rows can be formed simply by erecting the panel units along the tunnel axis direction at a predetermined interval, so installation and removal operations are easy, and by changing the slit dimensions, etc. It is possible to easily adjust the frequency of the sound to be reduced by changing the resonance frequency.

  Further, according to one aspect of the present invention, the panel row (11) is installed at an end of the panel row (11) on the tunnel wellhead side so as to close the space (5C) on the other surface side. It can be set as the structure which further has a soundproof door (17).

  According to this configuration, the low-frequency sound that is reduced when passing through the space on the other surface side and the sound other than the low frequency sound that passes through the space on the other surface side are blocked by the soundproof door, and noise that propagates to the tunnel wellhead is prevented. Can be reduced.

  According to another aspect of the present invention, the panel row (11) is provided in a pair so as to face each other, and the first partition wall (12) and the second partition wall (13) are at least the pair of panels. It can be set as the structure installed so that the space (5R, 5L) of the outer side of a row | line | column (11 * 11) may be obstruct | occluded.

  According to this configuration, the space between the pair of panel rows serves as a low-frequency sound propagation path, and the two spaces formed on both outer sides thereof serve as resonance spaces. Can be increased.

  According to another aspect of the present invention, the panel unit (21) includes a base portion (23) disposed on the other surface side and extending in the tunnel axis direction, and the base portion (23) in the tunnel axis direction. A pair of extending portions (24) extending from both ends to the one surface side, and the extending portions (24) give the slit (22) a predetermined depth (t). be able to.

  According to this configuration, since the resonance frequency can be changed according to the depth of the slit, the degree of freedom in design is increased, and the resonance sound absorption action by the resonance space and the slit can be more effectively achieved.

  Moreover, according to one side of this invention, it can be set as the structure by which the said base part (23) and the said extension part (24) are comprised combining the flat panel (25).

  According to this configuration, the shape and dimensions of the panel unit can be easily changed by changing the dimensions of the combined panels and the overlapping dimensions of the adjacent panels, so that the frequency adjustment of the sound to be reduced can be facilitated. Further, when storing or transporting the panel unit, the volume can be reduced by disassembling and stacking the panels, and the cost can be reduced.

  As described above, according to the present invention, it is possible to provide a tunnel low-frequency sound reduction device that can easily secure a pedestrian passage and can easily perform installation / removal work and frequency adjustment of a reduction target sound.

The perspective view of the tunnel low frequency sound reduction device concerning an embodiment 1 is a cross-sectional view of the tunnel low-frequency sound reducing device shown in FIG. III-III sectional view in FIG. IV-IV sectional view in Fig. 2 (A) Top view of panel unit (B) Front view of panel unit Explanatory drawing of the resonance frequency by the low frequency sound reduction device shown in FIG. Cross-sectional view of a tunnel low-frequency sound reduction device according to a modification

  Hereinafter, an embodiment of a tunnel low-frequency sound reducing device (hereinafter simply referred to as a low-frequency sound reducing device 10) according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a part of a tunnel 1 in which a low-frequency sound reduction device 10 is installed. The tunnel 1 is a so-called mountain tunnel, and concrete is sprayed on the surface of a natural ground excavated with a face, and the lining concrete 2 is constructed to finish the tunnel wall surface. Blasting takes place when excavating natural ground at the face. Blasting is an operation that uses explosives to crush the natural ground and generates low-frequency sound during an explosion. That is, the face where blasting is performed is a source of low-frequency sound. The debris, which is a crushed piece of ground from the blasting, is loaded onto a transport vehicle such as a dump truck at the face and carried out of the mine.

  As shown in FIG. 2, the lining concrete 2 includes arch concrete constructed in an arc shape, and a tunnel 1 is defined by the inner surface of the lining concrete 2.

  The low-frequency sound reduction device 10 is a device for reducing low-frequency sound generated at the face and propagating to the tunnel well. After tunnel excavation has progressed to some extent, in this embodiment, the lining concrete 2 is located near the well. After the construction, it is installed in the vicinity of the wellhead in the tunnel well, that is, between the low frequency sound source and the tunnel well. The low-frequency sound reduction device 10 is installed at a pair of panel rows 11 and 11 provided so as to be opposed to each other and along the tunnel axis direction, and at the end on the face side of the pair of panel rows 11 and 11. The first partition wall 12 and the second partition wall 13 installed at the end of the pair of panel rows 11 and 11 on the wellhead side are included as main components.

  A pair of panel row | line | columns 11 * 11 are arrange | positioned in the position which becomes substantially symmetrical with the tunnel center 1X (refer FIG. 2) as a centerline. In another embodiment, the pair of panel rows 11 and 11 may be arranged at positions where the distance from the tunnel center 1X is different. At the position where the low-frequency sound reduction device 10 is installed, the panel rows 11 and 11 make 3 in the direction in which the space 5 in the tunnel mine is perpendicular to the pair of tunnel axis directions (hereinafter, referred to as the left-right direction toward the face). Divided into two spaces. Hereinafter, the space between the pair of panel rows 11 and 11 is referred to as a central space 5C, and the two outer spaces (right and left) of the pair of panel rows 11 and 11 are the right space 5R and the left space 5L, respectively. Called. A pair of panel row | line | columns 11 and 11 are good to arrange | position with the width dimension of the grade which the conveyance vehicle which carries out a shear can pass.

  Here, partitioning does not mean that adjacent spaces are completely partitioned, but means that adjacent spaces are partitioned in the height range in which the panel row 11 is arranged. It is. Note that even though it is partitioned, both spaces communicate with each other via slits 22 formed in the panel row 11 as will be described later, and are not completely separated.

Each panel row 11 is configured by a plurality of panel units 21 arranged in the tunnel axis direction and extending vertically. In each panel row 11, all the panel unit 21, the tunnel height of the deployed position (the inner space vertical height) has a generally been the same height, is placed directly on the ground. The inner surface of the lining concrete 2 has an arch shape, and it is difficult to completely partition the three spaces 5R, 5C, and 5L by bringing the upper end of the panel unit 21 into surface contact with the lining concrete 2. As long as the lower end and the upper end of the panel unit 21 are in contact with the inner surface of the tunnel, it is preferable to completely partition the three spaces 5R, 5C, and 5L. In order to do this, the upper end of the panel unit 21 is shaped to fit the lining concrete 2, or a plate piece (not shown) is attached to the upper end of the panel row 11 along the tunnel extending direction. It is preferable to close a gap generated between the lining concrete 2 and the like. In other embodiments, the panel unit 21 may not be arranged directly on the ground. Further, when the gap between the upper end of the panel unit 21 and the lining concrete 2 is closed with a plate piece, the height dimension of the panel unit 21 may be different for each unit.

  As shown in FIG. 2, the first partition wall 12 is composed of two steel panels 14 and 14 that close the right space 5R and the left space 5L. In other words, the two panels 14 and 14 are configured so as to cover the entire right side space 5R and left side space 5L from the face side, and the central space 5C is open toward the face side space 5F. A pedestrian door 15 is provided at the lower part of each panel 14 so that the pedestrian can go back and forth between the space 5F on the face side, the right space 5R, and the left space 5L with respect to the low frequency sound reduction device 10. Yes. In addition, the panel 14 does not need to be a single sheet, and may be configured by combining a plurality of panel members.

  On the other hand, as shown in FIG. 1, the second partition wall 13 is configured in a single panel shape that closes the right space 5R and the left space 5L and covers the upper portion of the central space 5C from the wellhead side. A pedestrian door 16 is provided below each of the portions of the second partition wall 13 that close the right space 5R and the left space 5L, and the well-side space 5M and the right space from the low frequency sound reduction device 10 are provided. Pedestrians can come and go between 5R and left space 5L. Moreover, the center lower part of the left-right direction of the 2nd partition 13 becomes the opening 13a, and the double-sound opening type soundproof door 17 is installed in this opening 13a. The opening 13a is sized to allow the transport vehicle to pass through, and the soundproof door 17 is opened when the transport vehicle passes. That is, the central space 5C becomes a traffic area for the transport vehicle. In this embodiment, the 2nd partition 13 is comprised using the partition for sound insulation installed in the vicinity of a wellhead.

  When blasting, all the pedestrian doors 15 and 16 are closed, and the soundproof door 17 is also closed. Accordingly, when the central space 5C opened toward the face-side space 5F is transmitted from the face-side space 5F to the well-side space 5M, it becomes a main propagation path for low-frequency sound and passes through the central space 5C. The sound other than the low frequency sound reduced as described later and the low frequency sound passing through the central space 5C is further blocked by the soundproof door 17.

  As shown in FIG. 3 and FIG. 4, in each panel row 11, a plurality of panel units 21 are arranged at predetermined intervals in the tunnel axis direction. In other words, slits 22 extending vertically and having a predetermined width dimension are formed between adjacent panel units 21. The panel units 21 disposed at both ends in the tunnel axis direction are disposed at positions where the panel units 21 are connected to the first partition wall 12 or the second partition wall 13.

  Each panel unit 21 is arranged on the central space 5C side and extends in the tunnel axial direction, and a base 23 that defines the central space 5C, and a side opposite to the central space 5C from both ends of the base 23 in the tunnel axial direction ( The right panel row 11 has a pair of extending portions 24 and 24 that extend to the right space 5R side and the left panel row 11 to the left space 5L side. That is, the slit 22 is given a depth corresponding to the width dimension (lateral dimension) of the extension part 24 by the opposing extension parts 24 and 24 of the two panel units 21 and 21 adjacent to each other. Although all the panel units 21 are basically configured to have the same dimensions and the same shape, the panel units 21 disposed at both ends in the tunnel axial direction are the first partition 12 or the second partition. The extending portion 24 on the side connected to the partition wall 13 may be omitted.

  In the present embodiment, the width dimension (tunnel axis direction dimension) of the base portion 23 is about 1 m, and the width dimension of each extending portion 24, that is, the depth of the slit 22 is about 50 cm. As shown in FIG. 5, the base portion 23 is configured by combining two flat soundproof panels 25 each having a width of 50 cm and a height of about 2 m, and each extending portion 24 has a width of 50 cm and a high height. It is configured by combining two flat soundproof panels 25 of about 2 m in length.

  The soundproof panel 25 constituting the base portion 23 and the extension portion 24 can be disposed at a predetermined position by being fixed to a torii formwork (not shown). Or you may arrange | position the sound-insulation panel 25 in a predetermined position by standing and fixing to the pillar member which consists of H-shaped steel. In any case, it is advisable to take a refrain from the arch portion of the tunnel 1 and take measures to prevent overturning such as connecting the soundproof panel 25, the torii formwork, or the column member of the panel unit 21 adjacent in the tunnel axis direction. The upper portions of the panel unit 21 may be connected between the pair of panel rows 11 and 11 to prevent the overturn. In this case, the connecting member is arranged at a position higher than the transport vehicle.

  In another embodiment, the panel unit 21 may be configured by creating a plurality of boxes having a predetermined height that is U-shaped in a plan view as illustrated in FIG. 3 and stacking the boxes to a required height. In this case, after the boxes adjacent to each other in the vertical direction are connected to each other, the above-described measures for preventing the fall may be taken.

  Next, the effect and sound absorption principle of the low-frequency sound reduction device 10 configured as described above will be described.

  As shown in FIG. 6, the low-frequency sound reduction device 10 forms slit-like openings (slits 22) on the inner surfaces of a pair of panel rows 11 and 11 that define a central space 5C that is a propagation path of low-frequency sound. As a result, the structure is equivalent to a structure in which a plurality of single resonator sound absorbing structures 26 are continuously provided. Therefore, the low-frequency sound reduction device 10 is based on the same principle as the resonator sound-absorbing structure 26, and the space between the panel rows 11 and the side walls of the lining concrete 2 (the right-side space 5R) Or it can be said to be a slit-type sound absorbing structure that absorbs resonance in the left space 5L).

  And the frequency of the low frequency sound to reduce can be adjusted by setting suitably the tunnel axial direction dimension of the panel unit 21, and the width | variety (tunnel axial direction dimension) and depth (left-right direction dimension) of the slit 22. FIG.

ただし、ｃ：音速、ｐ：開口率（ｐ＝ｂ／Ｂ）、δ：開口端補正値（δ＝Ｋｂ）、Ｋ：定数であり、定数Ｋは、下式（２）となる。

The height of the slit 22 is a, the width of the slit 22 is b, the installation interval in the tunnel axis direction of the panel unit 21 is B, the depth of the slit 22 is t, and the air layer behind the panel row 11 (right space 5R or left space) When the depth of 5L) is L, the resonance frequency fr of the low-frequency sound reduction device 10 having the slit-type sound absorbing structure is expressed by the following equation 1.

However, c: sound velocity, p: aperture ratio (p = b / B), δ: aperture end correction value (δ = Kb), K: constant, and constant K is expressed by the following equation (2).

  If a = 4 m, b = 0.3 m, B = 1 m, t = 0.5 m, and L = 2.5 m, the resonance frequency fr is 20 Hz, and the sound absorption effect appears around this frequency. Increasing the resistance of the slit 22 decreases the sound absorption rate at the resonance frequency fr, but increases the frequency of sound absorption. Therefore, the frequency of sound absorption may be increased by disposing a sound absorbing material such as glass wool on the slit 22 (between adjacent panel units 21) or on the back surface of the slit 22 (right space 5R or left space 5L).

  Also, the size of the low-frequency sound reducing device 10 in the tunnel axis direction is appropriately the same as the wavelength of the low-frequency sound to be reduced. In the present embodiment, the frequency of the low frequency sound to be reduced is 20 Hz, and the tunnel axis direction dimension of the low frequency sound reducing device 10 is about 17 m, which is the same as the wavelength.

  Since the low-frequency sound reduction device 10 is configured in this manner, the central space 5C serves as a low-frequency sound propagation path as described above, and the right-side space 5R and the left-side space 5L communicate with the central space 5C via the slits 22. Therefore, the low frequency sound propagating through the central space 5C is reduced by the resonance sound absorbing action between the resonance space and the slit 22. And the pedestrian door 15 is provided in at least one of the parts which block | close the right space 5R and the left space 5L of the 1st partition 12 and the 2nd partition 13, and it is a passing space resonance space of a transport vehicle. The right space 5R or the left space 5L can be used as a pedestrian passage.

  The sound absorption effect by the low-frequency sound reduction device 10 is the first installed at the face side end portion of the panel row 11 so as to close at least one panel row 11 and one of the left and right spaces of the panel row 11. This is achieved by including the partition wall 12 and the second partition wall 13. That is, the configuration in which the panel rows 11 are provided in two rows and the resonance spaces are provided on both the left and right sides of the low-frequency sound propagation path plays a role of enhancing the sound absorption effect of the low-frequency sound reduction device 10.

  In the present embodiment, the panel unit 21 is disposed on the central space 5C side and extends in the tunnel axis direction, and the right space 5R or the left space 5L serving as a corresponding resonance space from both ends of the base 23 in the tunnel axis direction. Since the slit 22 has a predetermined depth by the extension 24, the resonance frequency fr is changed according to the depth of the slit 22. The degree of freedom of design is high.

  Further, in the present embodiment, the panel unit 21 is configured by combining the soundproof panel 25, so that the shape and dimensions of the panel unit 21 are changed by changing the dimensions of the soundproof panel 25 to be combined and the overlapping dimensions of the adjacent soundproof panels 25. Therefore, the frequency of the reduction target sound can be easily adjusted. Further, when storing or transporting the panel unit 21, the volume is reduced by disassembling and stacking the soundproof panel 25, thereby reducing the cost.

  FIG. 7 shows a cross section of the low-frequency sound reduction device 10 according to a modification. In this modification, a pair of panel rows 11 provided so as to face each other in the left-right direction have a height lower than that of the above-described embodiment, and a pair of panel rows 11 extending horizontally along the tunnel axis direction. It is provided so that the upper part of the panel row | line | column 11 * 11 may be connected. The panel row 11 provided horizontally has the same configuration as the other panel rows 11 except that the installation direction becomes horizontal. By arranging the panel row 11 in this way, in the tunnel 1, in addition to the central space 5C, the right space 5R and the left space 5L, the ceiling portion of the lining concrete 2 and the panel row 11 provided horizontally are provided. An upper space 5U is formed therebetween. The first partition 12 is shaped to close the upper space 5U in addition to the right space 5R and the left space 5L. Thereby, a low frequency sound is reduced also by the resonance sound absorption effect | action of the slit 22 and the upper space 5U of the panel row | line | column 11 provided horizontally.

  Although the description about specific embodiment is finished above, the low frequency sound reduction device 10 according to the present invention is not limited to the above embodiment. For example, in the above embodiment, the present invention is applied to the tunnel 1 that constructs the lining concrete 2, but it can also be applied to a tunnel that does not construct the lining concrete 2 or a tunnel that does not spray concrete. . Moreover, in the said embodiment, although the low frequency sound reduction apparatus 10 is installed after the construction of the lining concrete 2, installation of the low frequency sound reduction apparatus 10 may be performed at any time. For example, the low-frequency sound reduction device 10 may be installed before construction of the lining concrete 2, that is, after completion of concrete spraying, or when constructing inverted concrete, before construction or after construction.

  Moreover, in the said embodiment, the two panels 14 * 14 made from steel which obstruct | occlude the right space 5R and the left space 5L so that the center space 5C may open | release the 1st partition 12 toward the space 5F of the face side. However, like the second partition wall 13, a single panel (combining the panels) may cover (close) the upper portion of the central space 5 </ b> C. By adopting such a configuration, it is possible to increase the low-frequency sound reduction effect by the low-frequency sound reduction device. In this case, the first partition 12 may have the same shape as the second partition 13 except for the soundproof door 17.

  In the above embodiment, as described with reference to FIG. 6, in the pair of panel rows 11 and 11, the width b, depth t, interval B, and depth L of the slit 22 are uniformly set to the same dimensions. Some or all of these dimensions may be different for each slit 22. Thus, by making the dimensions of the slits 22 different, it is possible to cover a broader low frequency band and enhance the low frequency sound reduction effect.

  Furthermore, in the said embodiment, although the panel unit 21 is made into the U-shaped cross-sectional shape, it is good also as a rectangular cross-sectional shape, ie, a quadratic prism shape. Moreover, it is also possible to adopt a form in which only one panel row 11 is arranged or a form in which the second partition wall 13 is not provided. In addition, the specific configuration, shape, arrangement, quantity, material, and the like of each member and part can be changed as appropriate without departing from the spirit of the present invention. On the other hand, all elements of the structure of the low-frequency sound reduction device 10 shown in the above embodiment are not necessarily essential, and may be selected as appropriate.

1 Tunnel 5C Central space (space on the other side)
5L left space (space on one side)
5F Face face side 5M Wellhead side space 5R Right side space (space on one side)
DESCRIPTION OF SYMBOLS 10 Low frequency sound reduction device 11 Panel row | line | column 12 1st partition 13 Second partition 13a Opening 21 Panel unit 22 Slit 23 Base 24 Extension 25 Soundproof panel t Slit depth

Claims (5)

A tunnel low-frequency sound reduction device that is installed between a low-frequency sound source in a tunnel mine and a tunnel pit, and reduces low-frequency sound that propagates from the low-frequency sound source to the tunnel pit,
A panel row formed by a plurality of panel units which are erected along the tunnel axis direction and each have a height dimension substantially the same as the height of the tunnel at the arranged position ;
A first partition wall installed at an end of the panel row on the low frequency sound generation source side so as to close a space on one surface side of the panel row ;
And a second partition wall disposed so as to close the space of at least the one side of the panel row to the end of the tunnel wellhead side of the panel row,
A tunnel low-frequency sound reduction device characterized in that the space on the one surface side and the space on the other surface side of the panel row communicate with each other through a slit formed between adjacent panel units.   2. The tunnel low-circumference according to claim 1, further comprising a soundproof door installed at an end of the panel row on the tunnel well side so as to close the space on the other surface side of the panel row. Wave sound reduction device. The panel rows are provided in a pair so as to face each other,
It said first partition and said second partition wall, characterized in that it is installed so as to close the space of at least the outer side of the pair of the panel columns, tunnel low-frequency sound of claim 1 or claim 2 Reduction device.   The panel unit includes a base portion disposed on the other surface side and extending in the tunnel axis direction, and a pair of extending portions extending from the both ends of the base portion in the tunnel axis direction to the one surface side, The tunnel low frequency sound reducing device according to any one of claims 1 to 3, wherein the extending portion gives the slit a predetermined depth.   The tunnel low-frequency sound reduction device according to claim 4, wherein the base and the extension are configured by combining flat panels.

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