Blasting noise reduction device

Abstract

To provide a blast sound reduction device which can be easily prepared and easily secures a space on a work surface.SOLUTION: A blast sound reduction device 101 comprises a plurality of paper tubes 111-1 arranged in a direction intersecting with a J111 direction and a lid 160 blocking an opening of an end surface 122 of the tube 111-1. A hollow part 112 has a volume generating Helmholtz resonance to the blast sound.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a blast noise reduction device. [Background technology]

[0002] During tunnel extension work, work progresses while repeatedly firing blasts at the tunnel face. The frequency band of the blasting noise generated during blasting is wide, including low frequencies. The sound pressure of the blasting noise is also extremely high. Therefore, if the blasting noise leaks outside the tunnel, it will cause noise in the surrounding environment. In particular, low-frequency blasting noise will vibrate surrounding buildings and other structures if it leaks outside the tunnel.

[0003] To reduce blasting noise, a method has been proposed in which a sound-absorbing device designed to match the frequency characteristics of the blasting noise is placed inside a tunnel to suppress noise and vibration using the principle of Helmholtz resonance. For example, Patent Document 1 discloses an assembled sound absorber (blasting noise reduction device) including first to fourth side walls, an upper plate, a lower plate, and a partition wall. The sound absorption coefficient of the sound absorber disclosed in Patent Document 1 is estimated based on equivalent electrical circuit theory. For example, Patent Document 2 discloses a sound absorber (blasting noise reduction device) including multiple box-shaped Helmholtz resonators arranged in at least one of the vertical and horizontal directions. A through hole is formed in one side of the box-shaped Helmholtz resonator disclosed in Patent Document 2. In the blasting noise reduction device of Patent Document 2, the multiple box-shaped Helmholtz resonators are arranged so that the opening of the through hole faces outward. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5601545 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-074328 Summary of the Invention [Problem to be solved by the invention]

[0005] The blasting noise reduction devices of Patent Documents 1 and 2 described above require a large number of box-shaped Helmholtz resonators, more than 200 in number, to sufficiently reduce the blasting noise, which requires a huge amount of work and costs to prepare. Also, because the blasting noise reduction devices of Patent Documents 1 and 2 are grounded on the working floor (ground) inside the mine, it is difficult to secure space on the working floor.

[0006] The present invention provides a blast noise reduction device that is easy to set up and makes it easier to save space on a work surface. [Means for solving the problem]

[0007] The blasting noise reduction device of the present invention comprises a plurality of paper tubes arranged in a direction intersecting the axial direction, and a paper lid that covers one opening of the tubes, and the hollow portion of the tube has a volume that causes Helmholtz resonance in response to the sound of gunfire.

[0008] The blast noise reduction device described above can be easily prepared using ready-made paper tubes and lids as the tubes. Furthermore, because the blast noise reduction device can be made lightweight, it can be placed, for example, above a tunnel tunnel, which is a dead space, and the entire working surface of the tunnel can be used as a work space or a space for work vehicles to pass through.

[0009] In the above-described blasting noise reduction device, one end faces of the plurality of pipes in the axial direction may be arranged in the same plane as each other.

[0010] According to the above-mentioned blasting noise reduction device, when the axial lengths of the multiple pipes (hereinafter sometimes simply referred to as "pipe lengths") are equal, the other end faces of the multiple pipes are arranged in the same plane, making it easy to handle when moving or installing the blasting noise reduction device.When the lengths of the multiple pipes are different, the other end faces of the multiple pipes are not arranged in the same plane, but the blasting noise reduction device can be easily moved or installed by taking into account the length of the longest pipe.

[0011] In the above-described blasting noise reduction device, the cross-sectional shape of the pipe may be a rectangular frame shape.

[0012] According to the above-mentioned blasting noise reduction device, the plurality of pipes can be arranged with almost no gaps between them when viewed along the axial direction, thereby improving the blasting noise absorption rate and the blasting noise reduction effect of the blasting noise reduction device.

[0013] In the above-described blasting noise reduction device, a filter may be provided on the end face of the pipe to prevent impurities from entering the pipe.

[0014] According to the above-described blasting noise reduction device, the filter can prevent impurities other than air from entering the pipe, which allows multiple pipes to be reused without having to frequently clean the insides of the multiple pipes.

[0015] In the above-mentioned blasting noise reduction device, the tube comprises a main tube and a small tube that is shorter and has a smaller diameter than the main tube, the small tube is arranged in the hollow portion of the main tube, one end face of the main tube and one end face of the small tube are located at approximately the same position as each other in the axial direction of the main tube, and the device further comprises a secondary paper lid separate from the lid, the lid being arranged to cover the opening on the other end face of the main tube, and the secondary lid being arranged to cover the area of ​​the opening on one end face of the main tube other than the opening on one end face of the small tube.

[0016] According to the above-described blasting noise reduction device, the size and shape of each of the main pipe and the small pipe can be freely set or changed, and the frequency (resonant frequency) to be absorbed by the pipe can be freely adjusted with high precision.

[0017] The above-mentioned blasting noise reduction device may be provided on a platform formed on the tunnel surface.

[0018] By providing the above-mentioned blasting noise reduction device on the platform, the entire working surface within the tunnel can be utilized freely, and a large working space or space for work vehicles to pass through can be secured on the working surface. [Effects of the Invention]

[0019] According to the present invention, a blasting noise reduction device can be provided that is easy to prepare and makes it easy to secure space on the work surface. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic diagram showing the state inside a tunnel in which a blasting noise reduction device according to an embodiment of the present invention is installed. [Figure 2] FIG. 2 is a perspective view of the blasting noise reduction device shown in FIG. [Figure 3] FIG. 2 is a perspective view of a first modified example of the blasting noise reduction device shown in FIG. [Figure 4] 1. FIG. 4 is a perspective view of a part of a pipe provided in a second modified example of the blasting noise reduction device shown in FIG. [Figure 5] 5 is a cross-sectional view of the pipe taken along the line C1-C1 in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0021] Blast noise reduction devices according to embodiments of the present invention will be described below with reference to the drawings.

[0022] The blasting noise reduction device 101 is a device for reducing blasting noise generated during blasting, for example, during extension work of a tunnel 400 shown in FIG. 1. As shown in FIG. 1, a platform 410 extending into the tunnel is provided on the tunnel surface 402 of the tunnel 400. The platform 410 is provided on both sides of the tunnel surface 402 in the direction D2 (width direction), which is perpendicular to the direction D1 along which the tunnel 400 extends and parallel to the ground (work surface) 404. The platform 410 includes a support portion 412 and a fall prevention portion 414. The support portion 412 is formed in a plate shape and extends parallel to the ground 404 from the tunnel surface 402 toward the center of the tunnel 406 of the tunnel 400 in the direction D2. The fall prevention portion 414 is formed in a plate shape and extends vertically upward from a tip 413 of the support portion 412.

[0023] The blasting noise reduction device 101 is provided on the upper surface 415 of the support part 412 of the stand 410, and is arranged between the hole surface 402 and the fall prevention part 414 in the D2 direction.

[0024] As shown in FIG. 2, the blasting sound reduction device 101 includes a plurality of paper tubes 111-1. The peripheral wall 113 of the tubes 111-1 is formed of paper. Examples of the paper include so-called "paperboard" such as paper tube base paper, kraft paper, corrugated cardboard base paper, paperboard for paper containers, and building base paper, but are not limited to a specific type. The peripheral wall 113 is formed by laminating multiple papers, and the outermost or innermost layer may be made of water-repellent paper, waterproof paper, laminated paper, or the like. The thickness of the peripheral wall 113 is not particularly limited, but is, for example, 1 mm or more and 50 mm or less. By setting the paper thickness to an appropriate thickness, the strength of the tube 111-1 can be ensured while reducing the weight of the tube 111-1.

[0025] The multiple pipes 111-1 are arranged along a horizontal direction H101 and a vertical direction, i.e., a height direction V101. The H101 and V101 directions are perpendicular to each other and perpendicular to a J111 direction (axial direction) parallel to an axis X111 of the pipes 111-1. The multiple pipes 111-1 may be bound together by a binding tool (not shown).

[0026] The pipe 111-1 has a length corresponding to the frequency of the blasting sound generated inside the tunnel 400, i.e., the tunnel 406 shown in FIG. 1 . For example, the pipe 111-1 has a length that causes Helmholtz resonance when the blasting sound enters the hollow portion 112, e.g., approximately 1 / 4 of the wavelength converted from the peak frequency or center frequency of the blasting sound. In other words, the hollow portion 112 has a volume that causes Helmholtz resonance with the blasting sound. However, the frequency band of the blasting sound extends from low frequencies to a predetermined frequency. The lengths of the multiple pipes 111-1 may differ from one another depending on the multiple frequencies included in the frequency band of the blasting sound.

[0027] One end face 121 in the J111 direction of each of the multiple pipes 111-1 is arranged in the same plane perpendicular to the J111 direction. In other words, the end faces 121 of the multiple pipes 111-1 are aligned in the J111 direction. In the tunnel 400 shown in FIG. 1, the blasting sound reduction device 101 is arranged so that the axes X111 of the multiple pipes 111-1 are parallel to the D1 direction. In addition, the blasting sound reduction device 101 is arranged so that the end faces 121 of the multiple pipes 111-1 arranged in the same plane face the tunnel entrance in the D1 direction (i.e., the front side of the paper in FIG. 1).

[0028] 2, when the lengths of the multiple pipes 111-1 are the same, the other end faces 122 in the J111 direction of each of the multiple pipes 111-1 are arranged in the same plane perpendicular to the J111 direction. However, when the lengths of the multiple pipes 111-1 differ from each other depending on the multiple frequencies included in the frequency band of the blasting sound as described above, the end faces 122 of the multiple pipes 111-1 are shifted from each other in the J111 direction.

[0029] The cross-sectional shape of the pipe 111-1 intersecting the axis X111 (hereinafter, sometimes simply referred to as the "cross-sectional shape of the pipe") is a rectangular frame shape, for example, a square frame shape. The bottom edge 431 and the top edge 432 of the square cross section of the multiple pipes 111-1 are parallel to the installation surface of the blasting sound reduction device 101 (i.e., the top surface 415 of the support part 412 of the stand 410 in FIG. 1). The side edge portions 433, 434 of the bottom edge portion 431 of the square cross section of the multiple pipes 111-1 are perpendicular to the installation surface of the blasting sound reduction device 101. If k is a natural number of 2 or more, the position where the side edge portions 433, 434 of the pipes 111-1, 111-1 adjacent to each other in the H101 direction in the kth row from the bottom in the V101 direction meet overlaps with the center in the H101 direction of the top edge portion 432 of the pipe 111-1 in the (k-1)th row. The column number of the tube 111-1 in the bottom row is 1, and the column numbers increase toward the top. In other words, if the number of columns of the tubes 111-1 is N, the tubes 111-1 in each column from the first column to the Nth column are arranged alternately when viewed along the J111 direction.

[0030] As shown in Figures 1 and 2, in the blasting sound reduction device 101, the number of pipes 111-1 in each row decreases as the row number increases from the first row. With this configuration, when the blasting sound reduction device 101 is placed on the platform 410 as shown in Figure 1, the edges of the blasting sound reduction device 101 on both sides of the H101 direction (i.e., the D2 direction in the tunnel 406) that face the tunnel surface 402 in the D2 direction move toward the center of the tunnel 406 as they move upward, and are aligned with the tunnel surface 402. Note that in the configuration shown in Figures 1 and 2, the edges of the blasting sound reduction device 101 on both sides of the H101 direction that face the fall prevention unit 414 of the platform 410 in the D2 direction move away from the center of the tunnel 406 as they move upward, widening the gap between them and the fall prevention unit 414 in the D2 direction.

[0031] A filter 150 is provided on the end surface 121 of the pipe 111-1. The filter 150 prevents impurities such as dust and dirt from inside the tunnel 400 from entering the hollow portion (inside the pipe) 112, and allows only air containing the blasting sound to enter the hollow portion 112. The filter 150 is made of, for example, a wire mesh.

[0032] The end surface 122 of the pipe 111-1 is closed by a lid 160. The lid 160 prevents not only impurities such as dust and dirt from inside the tunnel 400, but also air from entering the hollow portion 112. The lid 160 is made of paper, just like the pipe 111-1.

[0033] The blasting noise reduction device 101 according to the present embodiment described above includes multiple paper tubes 111-1 arranged in a direction intersecting the J111 direction and a lid 160 covering one of the openings on the end face 122 of the tubes 111-1. The hollow portion 112 has a volume that generates Helmholtz resonance in response to the sound of gunfire. The blasting noise reduction device 101 can be easily prepared using, for example, pre-made paper tubes and lids for the tubes 111-1 and lid 160, thereby reducing costs. Furthermore, the paper tube 111-1 is significantly lighter than the steel or metal tubes used in conventional blasting noise reduction devices, thereby reducing the weight of the blasting noise reduction device 101. This allows the blasting noise reduction device to be placed above the tunnel tunnel 406, which is a dead space within the tunnel. As shown in Figure 1, the entire ground surface 404 within the tunnel can be used as a work space or a space for work vehicles to pass through. Furthermore, the blasting sound reduction device 101 can easily accommodate fluctuations in the frequency of blasting sounds and changes in the installation location.

[0034] In the above-described blasting sound reduction device 101, the end faces 121 of the multiple pipes 111-1 are arranged in the same plane. The blasting sound reduction device 101 is easy to handle when moving or installing. Furthermore, the blasting sound is evenly absorbed into the hollow portions 112 of the multiple pipes 111-1 from the same plane on which the end faces 121 are arranged, thereby enhancing the effect of reducing the blasting sound. As shown in FIGS. 1 and 2, when the multiple pipes 111-1 have the same length, the end faces 122 of the multiple pipes 111-1 are arranged in the same plane, making the blasting sound reduction device 101 easier to handle.

[0035] In the above-described blasting sound reduction device 101, the cross-sectional shape of the pipe 111-1 is rectangular. According to the blasting sound reduction device 101, multiple pipes 111-1 can be arranged with almost no gaps when viewed along the J111 direction. This improves the blasting sound absorption rate and blasting sound reduction effect of the blasting sound reduction device 101. Furthermore, the bottom edge 431 of the rectangular cross-section is in contact with the upper surface 415 of the support portion 412 of the base 410 (i.e., the installation surface of the blasting sound reduction device 101) or the upper edge 432 of the rectangular cross-section of the pipe 111-1 in the lower row. This allows the blasting sound reduction device 101 to be installed stably, and, for example, can easily prevent the blasting sound reduction device 101 from collapsing on the base 410.

[0036] In the above-described blasting sound reduction device 101, a filter 150 is provided on the end faces 121, 122 of the pipe 111-1 to prevent impurities from entering the hollow portion 112. According to the blasting sound reduction device 101, the filter 150 can prevent impurities other than air containing blasting sound information from entering the pipe. This allows multiple pipes 111-1 to be reused without having to frequently clean the hollow portions 112 of the multiple pipes 111-1. Furthermore, by removing impurities that are prevented from entering the hollow portions 112 by the filter 150, the hollow portions 112 of the pipes 111-1 are not partially blocked by impurities, and a decrease in the blasting sound reduction effect of the pipes 111-1 can be reliably suppressed.

[0037] The above-mentioned blasting sound reduction device 101 is mounted on a platform 410 formed on the tunnel surface 402 of the tunnel 400. By mounting the blasting sound reduction device 101 on the platform 410, the entire ground surface 404 inside the tunnel 400 can be utilized freely, and a large working space or space for work vehicles to pass through can be secured on the ground surface 404. This makes it possible to improve the efficiency of work in the tunnel 406, including extension work.

[0038] [Other embodiments] For example, as another embodiment of the blasting sound reduction device 101 described in the above embodiment, there is a blasting sound reduction device 102 shown in FIG. 3. Among the components of the blasting sound reduction device 102 shown in FIG. 3, components common to the blasting sound reduction device 101 are assigned the same reference numerals. In the blasting sound reduction device 102, the cross-sectional shape intersecting the axis X111 of the pipe 111-2 is annular. In the blasting sound reduction device 102, when viewed along the J111 direction, the multiple pipes 111-1 are arranged in a hexagonal close-packed manner. When viewed along the J111 direction, the position where the pipes 111-2, 111-2 adjacent to each other in the H101 direction in the k-th row in the V101 direction contact each other overlaps with the center of the pipe 111-2 in the (k-1)-th row. Figure 3 shows an example of a tube 111-2 with a circular cross-sectional shape, but the axial cross-sectional shape of the multiple tubes of the blasting noise reduction device of the present invention is not limited to a rectangular frame shape or a ring shape, and can be any shape that can generate Helmholtz resonance in the hollow portion, such as an elliptical frame shape or a triangular frame shape.

[0039] Another embodiment of the blasting sound reduction device 101 is the blasting sound reduction device 103 shown in Figures 4 and 5. Among the components of the blasting sound reduction device 103 shown in Figures 4 and 5, components common to the blasting sound reduction device 101 are assigned the same reference numerals. Note that Figures 4 and 5 illustrate only one pipe 111-3 among the multiple pipes 111-3 provided in the blasting sound reduction device 103. Like the multiple pipes 111-1 of the blasting sound reduction device 101, the multiple pipes 111-3 are arranged along each of the H101 direction and the V101 direction. Hereinafter, the direction perpendicular to the H101 direction and the V101 direction and parallel to the axial direction of the pipe 111-3 will be referred to as the L101 direction.

[0040] Tube 111-3 includes a main tube 114, a small tube 116 disposed in a hollow portion 118 of main tube 114, and lids 160 and 161. The cross section of small tube 116 in the axial direction is annular. Small tube 116 is disposed in hollow portion 118 by being positioned toward end face 131, one of both end faces in the L101 direction of main tube 114, which is the inlet side through which air enters hollow portion 118 when the L101 direction is aligned parallel to the D1 direction in FIG. 1 . In other words, end face 131 of main tube 114 and one end face 125 of small tube 116 in the L101 direction are positioned at the same position relative to each other in the L101 direction. Circumferential wall 117 of small tube 116 is in contact with the inner circumferential surface of peripheral wall 113 of main tube 114.

[0041] Main tube 114 has the same shape and dimensions as tube 111-2 described above. The length L2 of small tube 116 in the L101 direction is at least shorter than the length L1 of main tube 114 in the L101 direction, for example, 30% to 40% of length L1. The inner diameter S and outer diameter of small tube 116 are at least smaller than the inner diameter A of main tube 114, for example, 30% to 50% of inner diameter A.

[0042] Lid 161 has an opening 165 formed therein that is the same size and shape as the opening in end face 125 of small tube 116 when viewed along direction L101. Lid 161 is provided on end face 131 of main tube 114 with opening 165 aligned radially with the opening in end face 125 of small tube 116, centered on the axial direction of main tube 114. Lid 161 covers the opening in end face 131 of main tube 114 except for the opening in end face 125 of small tube 116. Lid 160 covers the opening in end face 132 of main tube 114. Each of lids 160 and 161 is adhered radially to the peripheral wall 113 of main tube 114 with an adhesive such as tape.

[0043] Main tube 114, small tube 116, and lids 160 and 161 are all made of paper. While the type of paper is not particularly limited, for example, the "paperboard" described for tube 111-1 above can be used. By incorporating each paper component, tube 111-3 functions as a Helmholtz resonator, similar to tubes 111-1 and 111-2 above. Air (blasting noise) entering tube 111-3 through the opening in end face 135 located on the inlet side of small tube 116 passes through hollow portion 119 of small tube 116, propagates from the opening in end face 136 to hollow portion 118 of main tube 114, and resonates in hollow portion 112.

[0044] As shown in FIG. 5, the size of the hollow portion 118 of the main tube 114 in the V101 direction, i.e., the diameter of the hollow portion 118, is defined as the inner diameter A of the main tube 114, and the hollow portion 119 of the small tube 116 is defined as except The volume of hollow portion 118 of main tube 114 is defined as V. The size of hollow portion 119 of small tube 116 in the L101 direction, i.e., the length of hollow portion 119, is defined as L2. In this case, the resonant frequency f of tube 111-3 is expressed by the following equations (1) and (2).

[0045]

number

[0046]

number

[0047] In equation (1), c represents the speed of sound. Based on equations (1) and (2), the inner diameter A, volume V, and lengths L1 and L2 are appropriately set so that the resonant frequency f of pipe 111-3 approximately matches the frequency of the blasting sound generated inside tunnel 400. The sizes and shapes of main pipe 114 and small pipe 116 are determined according to these parameters.

[0048] The above-mentioned formulas (1) and (2) are intended as a guide when the main tube 114 and the small tube 116 are cylindrical, as shown in Figures 4 and 5. As shown in Figures 1 and 2, the main tube 114 may be rectangular, or may have any shape other than a cylindrical or rectangular tube if it has a hollow portion. Like the main tube 114, the small tube 116 may also have any shape other than a cylindrical or rectangular tube if it has a hollow portion. When the main tube 114 and the small tube 116 each have a rectangular tube shape or any other shape, the lengths L1, L2, etc. can be set appropriately by replacing formula (2) with volume V = (cross-sectional area of ​​main tube 114 × length L1) - (cross-sectional area of ​​small tube 116 × length L2).

[0049] In the above-described blasting sound reduction device 103, the pipe 111-3 includes a main pipe 114 and a small pipe 116 that is shorter and has a smaller diameter than the main pipe 114. The small pipe 116 is disposed in a hollow portion 119 of the main pipe 114. In the pipe 111-3, an end face (one end face) 131 of the main pipe 114 and an end face (one end face) 135 of the small pipe 116 are positioned at approximately the same position as each other in the direction L101, which is parallel to the axial direction of the main pipe. The pipe 111-3 further includes a cover (auxiliary cover) 161 separate from the cover 160. The cover 160 is disposed so as to cover an opening (one opening of the pipe) of the end face (other end face) 132 of the main pipe 114, and the cover 161 is disposed so as to cover the area of ​​the opening of the end face 131 of the main pipe 114 other than the opening of the end face 135 of the small pipe 116.

[0050] By having such a configuration, blasting sound reduction device 103, like blasting sound reduction devices 101 and 102, can easily prepare these tubes by using, for example, pre-made cardboard tubes as main tube 114 and small tube 116, thereby reducing costs. Even if pre-made paper tubes are not used, multiple tubes 111-3 can be easily prepared by cutting new paper tubes to a length that corresponds to the resonance frequency that is matched to the blasting sound.

[0051] Furthermore, even if prefabricated paper tubes and paper lids are not used, the blasting sound reduction device 103 can easily prepare multiple tubes 111-1 by cutting new paper tubes to lengths set so that the blasting sound frequency approximately matches the resonant frequency within the tube. The target frequency (resonant frequency) to be absorbed by the tube 111-3 can be set according to the frequency of the blasting sound generated inside the tunnel 400. Furthermore, by changing the size and shape of the main tube 114 and the small tube 116 based on the above-mentioned equation (1) and adjusting the inner diameter A, volume V, and lengths L1 and L2, the target frequency to be absorbed by the tube 111-3 can be adjusted with high precision. Furthermore, the main tube 114, small tube 116, and lids 160 and 161 that make up the paper tube 111-3 are significantly lighter than the steel or metal pipes used in conventional blasting sound reduction devices, thereby reducing the weight of the blasting sound reduction device 103.

[0052] If the frequency band of the blasting noise changes, the length of the pipe 111-1 can be easily changed to match the changed frequency band by cutting the pipe 111-1 to an appropriate length so that the frequency of the blasting noise and the resonant frequency within the pipe are approximately equal, or by connecting another paper pipe to the pipe 111-1 using an adhesive or the like. As described above, the blasting noise reduction device 101 is lighter than conventional blasting noise reduction devices, and therefore can be easily installed and removed at any location in the tunnel 406. As a result, the efficiency of work to reduce blasting noise and extension work within the tunnel 400 can be improved.

[0053] Furthermore, in the above-described blasting sound reduction device 103, the main tube 114 and the small tube 116 have the same annular cross-sectional shape in the axial direction, but they may have different shapes. For example, the main tube 114 may have a rectangular cross-sectional shape in the axial direction, and the small tube 116 may have a circular cross-sectional shape in the axial direction. Also, a filter configured similarly to the filter 150 may be provided in the opening 165 formed in the lid 161. By providing the filter in the opening 165, it is possible to prevent impurities from entering the hollow portions 118 and 119, similar to the blasting sound reduction devices 101 and 102.

[0054] In the above-described blasting sound reduction device 103, one small pipe 116 is installed in the hollow portion 118 of one main pipe 114, but the number of small pipes 116 is not limited to a specific number. When multiple small pipes 116 are used, the lengths L101 of the multiple small pipes 116 may be the same as or different from each other. When multiple small pipes 116 are used, the relative arrangement of the multiple small pipes 116 in the hollow portion 118 is not particularly limited and can be adjusted according to the frequency of the blasting sound generated inside the tunnel 400. In such a case, the resonant frequency f of pipe 111-3 is changed from equation (1), but can be calculated by numerical calculation or the like.

[0055] Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and can be modified within the scope of the spirit of the present invention as defined in the claims.

[0056] In the blasting sound reduction device 101 described in the above embodiment, the fall prevention portion 414 extends linearly in the D3 direction along the vertical direction. For example, the edges of the blasting sound reduction device 401 on both sides in the H101 direction that face the fall prevention portion 414 of the stand 410 in the D2 direction may extend along the D3 direction. The cross-sectional shape and cross-sectional size of the multiple pipes 111-1 may be adjusted so that the aforementioned edges are formed linearly along the D3 direction.

[0057] In the blasting sound reduction device 101 described in the above embodiment, the mounts 410 are provided on both sides of the tunnel surface 402 in the D2 direction. For example, one mount 410 may be provided at the top of the tunnel 406. In that case, fall prevention units 414 may be provided at the side ends (tips) of the support unit 412 on both sides in the D2 direction. In addition, the arrangement shape of the multiple pipes of the blasting sound reduction device is changed as appropriate to fit the space between the support unit 412 of the mount 410 and the opposing tunnel surface 402. [Explanation of symbols]

[0058] 101, 102... Blasting noise reduction device 111-1, 111-2, 111-3...tube 121...End face (one end face) 122...End face 131, 135...End face (one end face) 132...End face (other end face) 150...filter 400...Tunnel 402...Pig surface 410…mounting stand J111…Direction (axial direction)

Claims

1. A plurality of paper tubes arranged in a direction intersecting the axial direction; a paper lid that closes one opening of the tube; Equipped with The hollow portion of the tube is a volume that causes Helmholtz resonance in response to blasting sound, The pipe comprises a main pipe and a small pipe that is shorter and has a smaller diameter than the main pipe, the small tube is disposed in the hollow portion of the main tube; one end surface of the main pipe and one end surface of the small pipe are located at substantially the same position in the axial direction of the main pipe, Further provided is a paper sub-lid separate from the lid, the lid is disposed so as to close the opening on the other end surface of the main tube, the secondary cover is disposed so as to close a region of the opening on one end surface of the main tube other than the opening on one end surface of the small tube, the peripheral wall of the small tube is in contact with the inner peripheral surface of the peripheral wall of the main tube, When the inner diameter of the main tube is A, the volume of the hollow portion of the main tube excluding the hollow portion of the small tube is V, the length of the main tube is L1, the length of the hollow portion of the small tube is L2, the inner diameter of the small tube is S, the resonant frequency of the tube is f, and the speed of sound is c, a blasting sound reduction device that satisfies the following equations (1) and (2). [Equation 1] [Equation 2]

2. One end surface of each of the plurality of pipes in the axial direction is arranged in the same plane. The blasting noise reduction device according to claim 1.

3. The cross-sectional shape of the tube is a rectangular frame shape.

3. A blasting noise reduction device according to claim 1 or 2.

4. A filter is provided on the end surface of the tube to prevent impurities from entering the tube. A blasting noise reduction device according to any one of claims 1 to 3.

5. It is installed on a platform formed on the tunnel surface. A blasting noise reduction device according to any one of claims 1 to 4.

Images