Blast noise reduction device installation structure inside tunnel

Abstract

To provide a tunnel installation structure for a blasting noise reduction device capable of securing a space on a work floor.SOLUTION: An tunnel installation structure for a blasting noise reduction device includes a main tube 111 made of paper and a lid 161 made of paper that closes one opening of the main tube, and a tubular blasting noise reduction device 101 having a volume in which a hollow part of the main tube causes Helmholtz resonance with respect to the blasting noise is installed in a tunnel 400 under construction. A plurality of blasting noise reduction devices are arranged so that the axial direction of the main tube is oriented vertically, and the plurality of blasting noise reduction devices are erected in the vicinity of a side wall 402 in the tunnel.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a structure for installing a blasting noise reduction device inside a tunnel. [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 can 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 have the problem that it is difficult to secure space on the working floor because a large number of more than 200 box-shaped Helmholtz resonators are installed on the working floor (ground) inside the mine.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a structure for installing a blasting noise reduction device inside a tunnel that can secure space on the work floor. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the tunnel installation structure for a blasting sound reduction device of the present invention is a tunnel installation structure for a blasting sound reduction device that comprises a paper main tube and a paper lid that covers one opening of the main tube, and in which a cylindrical blasting sound reduction device is installed in a tunnel under construction, the hollow portion of the main tube having a volume that causes Helmholtz resonance in response to gunfire sounds, and is characterized in that a plurality of the blasting sound reduction devices are arranged so that the axial direction of the main tube is oriented vertically, and the plurality of blasting sound reduction devices are erected near the side walls of the tunnel.

[0008] According to this invention, by installing a cylindrical blasting noise reduction device upright, the installation space for the blasting noise reduction device can be reduced. Also, by arranging multiple blasting noise reduction devices near the side walls of the tunnel, they do not interfere with the loading and unloading of materials. As a result, space on the work floor can be secured.

[0009] In addition, in the present invention, the plurality of blasting noise reduction devices may be arranged on a stand.

[0010] In the present invention, the pedestal may include a movement mechanism.

[0011] Furthermore, in the present invention, one end faces of the plurality of main tubes in the axial direction may be arranged in the same plane. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a structure for installing a blasting noise reduction device inside a tunnel, which allows space to be secured above the work floor. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing the state inside a tunnel in which a blasting noise reduction device according to this embodiment is installed. FIG. [Figure 2] 1 is a perspective view (partially cut away) of a blasting noise reduction device according to an embodiment of the present invention; [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is a perspective view of the blasting noise reduction unit of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a structure for installing a blasting noise reduction device in a tunnel according to an embodiment of the present invention will be described with reference to FIGS.

[0015] As shown in Figure 1, the blasting sound reduction unit 200 equipped with the blasting sound reduction device 101 is a unit for reducing the blasting sound generated when blasting is performed, for example, during extension work of a tunnel 400. The extension direction of the tunnel 400 is defined as the depth direction D1, the horizontal direction perpendicular to the depth direction D1 is defined as the width direction D2, and the directions perpendicular to the depth direction D1 and the width direction D2 are defined as the up-down direction D3.

[0016] As shown in FIGS. 2 and 3 , the blasting noise reduction device 101 includes a paper main tube 111. The main tube 111 is a cylindrical body having a circular cross section intersecting the axis O. The peripheral wall 113 of the cylindrical main tube 111 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, etc. 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 main tube 111 can be ensured while reducing the weight of the main tube 111.

[0017] The blasting noise reduction device 101 comprises a main tube 111, a small tube 116 disposed in a hollow portion 118 of the main tube 111, and lids 160, 161 attached to both ends of the main tube 111 in the axial direction.

[0018] The cross-sectional shape of small tube 116 in the axial direction is annular. Small tube 116 is disposed in hollow portion 118 near one of the axial end faces (the lid 161 side) of main tube 111. In the axial direction, end face 131 of main tube 111 and one end face 135 of small tube 116 are located at the same position. Circumferential wall 117 of small tube 116 is in contact with the inner circumferential surface of circumferential wall 113 of main tube 111. Note that circumferential wall 117 of small tube 116 does not have to be in contact with the inner circumferential surface of circumferential wall 113 of main tube 111.

[0019] The axial length L2 of the small tube 116 is at least shorter than the axial length L1 of the main tube 111, for example, 30% to 40% of length L1. The inner diameter S of the small tube 116 is at least smaller than the inner diameter A of the main tube 111, for example, 30% to 50% of inner diameter A.

[0020] Lid 161 has an opening 165 formed therein that, when viewed axially, has the same size and shape as the opening in end face 135 of small tube 116. Lid 161 is attached to end face 131 of main tube 111 with opening 165 aligned radially with the opening in end face 135 of small tube 116, centered on axis O of main tube 111. Lid 161 closes the area of ​​the opening in end face 131 of main tube 111 other than the opening in end face 135 of small tube 116.

[0021] Lid 160 closes the opening at end face 132 of main pipe 111. Lid 160 prevents not only impurities such as dust and dirt from inside tunnel 400 but also air from entering hollow portion 118. Each of lids 160, 161 is adhered to peripheral wall portion 113 of main pipe 111 from the outside in the radial direction with an adhesive such as tape.

[0022] The main tube 111, small tube 116, and lids 160, 161 are all made of paper. There are no particular limitations on the type of paper, but the aforementioned "paperboard" is used, for example. By incorporating each paper component, the main tube 111 becomes a Helmholtz resonator. Air containing the blast sound propagates from the opening in the end face 135 located on the inlet side of the small tube 116 through the hollow portion 119 of the small tube 116 to the hollow portion 118 of the main tube 111, where it resonates.

[0023] As shown in Figure 3, the diameter (inner diameter) of hollow portion 118 of main tube 111 is A, and the volume of hollow portion 118 of main tube 111 including hollow portion 119 of small tube 116 is V. The axial size of hollow portion 119 of small tube 116, i.e., the length of hollow portion 119, is L2. In this case, the resonant frequency f of main tube 111 is expressed by the following equations (1) and (2).

[0024]

number

[0025]

number

[0026] In equation (1), c represents the speed of sound. Based on equations (1) and (2), the diameter (inner diameter) A, volume V, and lengths L1 and L2 are appropriately set so that the resonant frequency f of main pipe 111 approximately matches the frequency of the blasting sound generated inside tunnel 400, and the sizes and shapes of main pipe 111 and small pipe 116 are determined according to these parameters.

[0027] The above-mentioned formulas (1) and (2) are intended as a guide when the main pipe 111 and the small pipe 116 are cylindrical, as shown in FIGS. 2 and 3. The main pipe 111 of the blasting sound reduction device 101 may be rectangular, or may have any shape other than a cylindrical or rectangular pipe, as long as it has a hollow portion. Similarly to the main pipe 111, the small pipe 116 may have any shape other than a cylindrical or rectangular pipe, as long as it has a hollow portion that communicates with the hollow portion of the main pipe 111. When the main pipe 111 and the small pipe 116 each have a rectangular or any other shape, the lengths L1, L2, etc. can be set appropriately by replacing formula (2) with volume V = (cross-sectional area of ​​the main pipe 111 × length L1) - (cross-sectional area of ​​the small pipe 116 × length L2).

[0028] The blasting noise reduction device 101 uses, for example, ready-made cardboard tubes as the main tube 111 and the small tubes 116, so that these tubes can be easily prepared and costs can be reduced.

[0029] Even if a pre-made paper tube or paper lid is not used, the blasting sound reduction device 101 can be easily prepared by cutting a new paper tube to a length 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 blasting sound reduction device 101 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 111 and the small tube 116 based on the above-mentioned equation (1) and adjusting the diameter (inner diameter) A, volume V, and lengths L1 and L2, the target frequency to be absorbed by the blasting sound reduction device 101 can be adjusted with high precision. Furthermore, the main tube 111, small tube 116, and lids 160 and 161 that make up the paper blasting sound reduction device 101 are significantly lighter than the pipes used in conventional blasting sound reduction devices, such as steel or metal pipes, thereby reducing the weight of the blasting sound reduction device 101.

[0030] If the frequency band of the blasting noise changes, the length of the blasting noise reduction device 101 can be easily shortened or lengthened to match the changed frequency band by cutting the blasting noise reduction device 101 to an appropriate length that approximately matches the blasting noise frequency and the resonant frequency within the pipe, or by connecting another paper pipe to the blasting noise reduction device 101 using adhesive or the like. Because the blasting noise reduction device 101 is lighter than conventional blasting noise reduction devices, it can be easily installed at any location in the tunnel 406 and moved or removed from any location. As a result, the efficiency of work to reduce blasting noise and extension work within the tunnel 400 can be improved.

[0031] In the blasting sound reduction device 101, the cross-sectional shapes in the axial direction of the main tube 111 and the small tube 116 are both annular, but they may have different shapes. For example, the cross-sectional shape in the axial direction of the main tube 111 may be a rectangular frame, and the cross-sectional shape in the axial direction of the small tube 116 may be annular. Also, a filter may be provided in the opening 165 formed in the lid 161. By providing the filter in the opening 165, it is possible to more reliably prevent impurities from entering the hollow portions 118 and 119.

[0032] In the blasting sound reduction device 101 of this embodiment, one small pipe 116 is installed in the hollow portion 118 of one main pipe 111, but the number of small pipes 116 is not particularly limited. When multiple small pipes 116 are used, the axial lengths of the multiple small pipes 116 may be the same as or different from one another. 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 the blasting sound reduction device 101 is changed from equation (1), but can be calculated by numerical calculation or the like.

[0033] As shown in FIGS. 1 and 4 , in this embodiment, a blasting sound reduction unit 200 equipped with a blasting sound reduction device 101 is disposed near a side wall 402 of a tunnel 400. For example, the blasting sound reduction unit 200 is disposed within one meter of the side wall 402 inside the tunnel 400. Furthermore, during the construction of the tunnel 400, a soundproof door (soundproof wall) may be installed to prevent blasting noise from leaking to the outside. In this case, the blasting sound reduction unit 200 should be disposed approximately 100 meters away from the soundproof door. Furthermore, the blasting sound reduction unit 200 should be disposed approximately 20 meters away from materials placed inside the tunnel 400. The blasting sound reduction unit 200 is configured by mounting a plurality of blasting sound reduction devices 101 on a platform 210. A plurality of the blasting sound reduction devices 101 are arranged on the platform 210 along both the width direction D2 and the depth direction D1. The blasting sound reduction device 101 is erected on the stand 210 so that the cylindrical axis O faces the up-down direction (vertical direction) D3. The blasting sound reduction device 101 is arranged so that the lid 161 side is at the upper end. Multiple blasting sound reduction devices 101 may be bound together by a binding tool (not shown).

[0034] The blasting sound reduction units 200 are arranged in a total of 12 blasting sound reduction devices 101, two in the width direction D2 and six in the depth direction D1. For example, a plurality of blasting sound reduction units 200 (for example, four units) are installed in series in the depth direction D1 along the side wall 402 of the tunnel 400. In Fig. 1, the blasting sound reduction units 200 are arranged near the side wall 402 on both sides in the width direction D2 of the tunnel 400, but the blasting sound reduction units 200 may be arranged only near one side wall 402 in the width direction D2 of the tunnel 400.

[0035] The platform 210 has a bottom plate 211 made of a steel plate such as a scaffolding board, and a plurality of steel single pipes 212 that serve as frame materials. Casters (moving mechanisms) 213 are attached to the lower ends of corner single pipes 212A erected at the four corners of the platform 210. By attaching the casters 213, the blasting sound reduction unit 200 can be installed in a freely movable manner. In addition, at a predetermined height of the platform 210, anti-tip single pipes 212B are provided around the entire periphery to prevent the blasting sound reduction device 101 from tipping over. The bottom plate 211 may be made of a mesh plate material such as expanded metal.

[0036] The main pipe 111 of the blasting sound reduction device 101 mounted on the blasting sound reduction unit 200 has a length corresponding to the frequency of the blasting sound generated inside the tunnel 400, i.e., the tunnel 406. For example, the main pipe 111 has a length that causes Helmholtz resonance when the blasting sound enters the hollow portion 118, 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 118 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 length of the main pipe 111 may be different from each other depending on the multiple frequencies included in the frequency band of the blasting sound.

[0037] The end faces 131 of the multiple blasting sound reduction devices 101 mounted on the blasting sound reduction unit 200 are arranged in the same horizontal plane. In other words, the end faces 131 of the multiple main body pipes 111 are aligned horizontally. Within the tunnel 400, the blasting sound reduction devices 101 are arranged so that the axes O of the multiple main body pipes 111 face the vertical direction D3.

[0038] 4, the other end faces 132 of the multiple blasting sound reduction devices 101 are placed on the bottom plate 211 of the stand 210. However, if the lengths of the main body tubes 111 of the multiple blasting sound reduction devices 101 differ from one another depending on the multiple frequencies included in the frequency band of the blasting sound, the positions of the end faces 132 of the multiple blasting sound reduction devices 101 are offset from one another. For example, an interposing member may be placed on the bottom plate 211 on the side of the end face 132 of the shorter main body tube 111 to align the position of one end face 131, and the main body tube 111 may then be placed on top of that.

[0039] The blasting noise reduction unit 200 described above includes multiple paper blasting noise reduction devices 101 arranged on a platform 210. The hollow portion 118 of the main tube 111 has a volume that generates Helmholtz resonance in response to gunfire sounds. The blasting noise reduction device 101 can be easily prepared using, for example, pre-made paper tubes and paper lids for the main tube 111 and lids 160, 161, reducing costs. Furthermore, the paper main tube 111 is significantly lighter than conventional blasting noise reduction devices, such as steel or metal tubes, thereby reducing the weight of the blasting noise reduction device 101. By placing the elongated blasting noise reduction unit 200 in the depth direction D1 near the side wall 402 of the tunnel 406, which is a dead space within the tunnel 400, as shown in Figure 1, it does not obstruct the work area within the tunnel. Most of the work floor 404 can be reserved as a work space or space for work vehicles to pass through. Furthermore, it is possible to easily respond to fluctuations in the frequency of the blasting sound and changes in the installation location by adjusting the length of the blasting sound reduction device 101. Furthermore, the number of blasting sound reduction devices 101 to be mounted on the blasting sound reduction unit 200 and the number of blasting sound reduction units 200 to be installed in the tunnel 400 can be set as appropriate.

[0040] In the blasting sound reduction unit 200, the end faces 131 of the multiple blasting sound reduction devices 101 are arranged in the same plane. In addition, since the blasting sound reduction unit 200 has a base 210, it is easy to handle when moving or installing. Furthermore, the blasting sound can be evenly absorbed into the hollow portions 118 of the multiple blasting sound reduction devices 101 from the same plane on which the end faces 131 are arranged, thereby enhancing the effect of reducing the blasting sound. Note that the end faces 131 of the multiple blasting sound reduction devices 101 do not have to be arranged in the same plane.

[0041] The blasting sound reduction device 101 is provided with lids 160, 161 on the end faces 131, 132 of the main body tube 111 to prevent impurities from entering the hollow portion 118. According to the blasting sound reduction device 101, the lids 160, 161 can prevent impurities other than air containing blasting sound from entering the tube. This allows the blasting sound reduction device 101 to be reused without having to frequently clean the hollow portions 118 of multiple blasting sound reduction devices 101. Furthermore, by removing impurities that are prevented from entering the hollow portions 118 by the lids 160, 161, the hollow portions 118 of the blasting sound reduction device 101 are not partially blocked by impurities, etc., and a decrease in the blasting sound reduction effect of the blasting sound reduction device 101 can be reliably suppressed.

[0042] A plurality of blasting sound reduction devices 101 are mounted on a platform 210 and configured as a blasting sound reduction unit 200. The blasting sound reduction unit 200 is configured long and narrow in the depth direction D1 of the tunnel 406 of the tunnel 400, so it can be installed without interfering with work. Also, because it is configured as a unit, it is easy to move. This makes it possible to improve the efficiency of work in the tunnel 406, including extension work.

[0043] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and can be modified within the scope of the gist of the present invention as defined in the claims.

[0044] In the blasting sound reduction unit 200 described in the above embodiment, a configuration in which 12 blasting sound reduction devices 101 are mounted on the stand 210 is described, but the number of blasting sound reduction devices 101 to be mounted on the stand 210 may be set as appropriate.

[0045] In the above embodiment, the blasting sound reduction device 101 has been described as being cylindrical, but the shape of the blasting sound reduction device 101 is not limited to this. For example, the blasting sound reduction device 101 may be a rectangular tube, a tube with an elliptical cross section, or a tube with a triangular cross section.

[0046] In the above embodiment, the base 210 is described as being composed of the bottom plate 211 and the single pipe 212, but the base 210 may have other structures. Also, although the base 210 is provided with the casters 213, the casters 213 may be omitted. In that case, the blasting sound reduction unit 200 may be transported and moved by heavy machinery.

[0047] The blasting sound reduction unit 200 in the above embodiment uses a mount 210 that is long in the depth direction D1, but if there is sufficient installation space, it may also be configured to place multiple blasting sound reduction devices 101 on a mount that is square in plan view or a mount that is long in the width direction D2. [Explanation of symbols]

[0048] 101...Blast noise reduction device 111...Main tube 118...Hollow part 131...end face 161…Lid 200...Blast noise reduction unit 210…mounting stand 213... Caster (movement mechanism) 400...Tunnel 402…Side wall O…Axis line

Claims

1. The tunnel construction includes a cylindrical paper main body tube and paper covers that close the main body openings on both sides of the axial direction of the main body tube, and the hollow portion of the main body tube has a volume that causes Helmholtz resonance in response to blasting noise. A plurality of the blasting noise reduction devices are arranged so that the axial direction of the main body pipe is oriented vertically, The plurality of blasting noise reduction devices are erected near the side walls of the tunnel, The plurality of blasting noise reduction devices are arranged on a platform, One of the lids has an opening of the same size as the opening at the end face of the small tube disposed in the hollow portion of the main tube, the other lid is provided to close the main body opening of the main body tube, the end faces of the body tubes in the axial direction on which the one lid is provided are arranged in the same plane as each other, A tunnel installation structure for a blasting noise reduction device, characterized in that if the heights of the other axial end faces on which the other lids are provided in the multiple main tubes are different from each other, an intervening member is placed between the platform and the blasting noise reduction device to adjust the height of the one lid.

2. 2. The tunnel installation structure for a blasting noise reduction device according to claim 1, wherein the platform is provided with a movement mechanism.

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