Modular acoustic black hole energy sink for a tunnel and system and method of maintenance thereof

Abstract

The application discloses a modular acoustic black hole energy dissipation unit for a tunnel and a system and a maintenance method thereof. The energy dissipation unit comprises at least one of a wall-mounted unit and a trackside clamping unit; the wall-mounted unit comprises an ABH thinning area with a power-law function thickness distribution and a first damping layer covering a residual thickness area in an energy gathering center of the ABH thinning area; and the trackside clamping unit comprises a clamp assembly, an ABH plate with a power-law function thickness distribution and a second damping layer laid on an energy gathering area of the ABH plate. The application dissipates reverberation sound energy through the wall-mounted unit, suppresses rail vibration through the trackside clamping unit, and realizes sound field-vibration source cooperative control; the clamp contact surface of the trackside clamping unit is subjected to hardening treatment or a friction-enhancing coating, cooperates with high-reliability fasteners and a secondary safety structure, and improves long-term service reliability; and state-based predictive maintenance is realized in combination with intelligent bolts. The application is suitable for modular installation, quick replacement and intelligent operation and maintenance in a tunnel.

Description

Technical Field

[0001] This invention relates to the field of vibration and noise reduction technology for rail transit, specifically to a modular acoustic black hole energy dissipation unit for tunnels, its system, and maintenance method. Background Technology

[0002] Due to their enclosed or semi-enclosed acoustic boundary conditions, urban rail transit tunnels generally face the problem of both enhanced sound field reverberation and structural vibration transmission. The wheel-rail noise and aerodynamic noise generated during train operation are reflected multiple times between the rigid lining walls, easily forming high reverberation sound pressure levels in the mid-frequency and low-mid-frequency ranges; at the same time, rail vibration can be transmitted along the rail-fastener-ballast-lining path and induce radiated noise from the retaining structure.

[0003] Existing tunnel sound absorption and vibration reduction measures typically have the following shortcomings: traditional porous sound-absorbing materials are prone to moisture and blockage in high-humidity and dusty environments, resulting in significant long-term performance degradation; trackside dampers or tuned mass vibration absorbers mostly operate on a narrow frequency band, and the clamping connection is prone to fretting wear under long-term high-frequency vibration, leading to connection stiffness drift.

[0004] Acoustic black hole (ABH) technology provides a new technical approach for structural vibration reduction by continuously reducing the structural thickness along a specific direction according to a power law, causing bending waves to converge towards the thinner end and dissipate in the damping material. However, there is still a relative lack of engineering solutions for tunnel scenarios, especially in terms of modular installation, long-term reliable connection, and condition-based maintenance, where there is still room for improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a modular acoustic black hole energy dissipation unit, its system, and maintenance method that can achieve coordinated control of "sound field suppression and vibration dissipation" in the environment of tunnels where reverberant sound fields and rail vibrations coexist.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, a modular acoustic black hole energy dissipation unit is provided, comprising at least one of the following: A wall-mounted unit, the wall-mounted unit comprising an ABH thinning region having a power-law function thickness distribution and a first damping layer covering the residual thickness region of the energy accumulation center of the ABH thinning region; A trackside clamping unit, comprising a clamping assembly for clamping onto a rail, an ABH plate with a power-law thickness distribution fixed to the clamping assembly, and a second damping layer laid in the energy accumulation area of ​​the ABH plate. The ABH thinning zone and the thickness variation of the ABH plate both follow the relationship... ,in, xIt is the radial distance measured from the center of energy accumulation or the center of the energy accumulation region outwards. The residual thickness reserved at the center of energy accumulation or the center of an energy accumulation region. This is a scaling factor related to the material and initial thickness. m It is a power exponent, and m ≥2.

[0007] The wall-mounted unit mainly acts on the tunnel sound propagation path, converging bending wave energy through the ABH thinning zone and dissipating it through the first damping layer to weaken sound reflection and reduce reverberation; the trackside clamping unit mainly acts on the vibration source, converging rail vibration energy through the ABH plate and dissipating it through the second damping layer to suppress vibration propagation and noise radiation.

[0008] This invention achieves efficient heat dissipation of the flexural wave vibration energy concentrated in the energy accumulation center by retaining a residual thickness area and applying a damping layer thereon, while ensuring structural strength and processing feasibility, thereby significantly improving broadband energy dissipation efficiency.

[0009] Furthermore, the wall-mounted unit is a multi-layer composite panel structure, which also includes an outer panel as the sound-facing surface and load-bearing structure, an encapsulation component for edge sealing and installation, and a core layer composed of honeycomb structure or acoustic metamaterial cells disposed between the outer panel and the ABH thinning zone.

[0010] Furthermore, the encapsulation component includes a sealing part and a connecting part; the sealing part includes a weather-resistant sealant and a mechanical pressure strip for pressing the weather-resistant sealant; the connecting part is a quick-release connector for fixing the wall mounting unit to the tunnel wall.

[0011] Furthermore, the clamping assembly includes a first clamp and a second clamp used in conjunction, and the contact surface between the clamping assembly and the rail is surface hardened or coated with a friction-enhancing coating to suppress fretting wear under long-term high-frequency vibration.

[0012] Furthermore, the surface hardening treatment is nitriding, and the depth of the hardened layer is 0.2-0.8 mm.

[0013] Furthermore, the trackside clamping unit is secured by at least one high-reliability fastener, including a double-layer wedge locking washer, an all-metal locking nut, or a smart bolt; when the high-reliability fastener is a smart bolt, the smart bolt integrates a sensor for monitoring preload and a wireless transmission module; the trackside clamping unit also includes an anti-loosening wire or an anti-fall-off baffle as a secondary safety structure to improve long-term service reliability.

[0014] Furthermore, the power index m Satisfy 2.0≤m ≤5.0, preferably 2.0≤ m ≤3.5, and residual thickness hres It ranges from 0.5 to 2.0 mm.

[0015] Furthermore, the railside clamping units are arranged along the length of the rail, and the spacing between adjacent railside clamping units is an integer multiple of the rail fastener spacing, preferably 1-3 times the rail fastener spacing.

[0016] Secondly, a tunnel vibration reduction and noise reduction system comprising the aforementioned modular acoustic black hole energy dissipation unit is provided.

[0017] Thirdly, a maintenance method based on intelligent bolt preload monitoring data is provided, including the following steps: Acquire real-time or historical preload monitoring data of smart bolts in the trackside clamping unit; The preload monitoring data is compared with a preset warning threshold, which is 70-90% of the initial preload. When the preload monitoring data is lower than the warning threshold, a maintenance work order is generated. The maintenance work order includes at least the location identification information of the trackside clamping unit that needs to be maintained and the recommended maintenance measures.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: 1. By introducing the wall-mounted unit and the trackside clamping unit into the same technical system, this invention can separately address the reverberation sound field of the tunnel and the vibration of the rail, and has the ability to synergistically suppress the source and the propagation path.

[0019] 2. By combining the ABH structure with a local damping layer, this invention can capture and dissipate broadband bending wave energy, thereby improving the low-frequency noise reduction effect in tunnels.

[0020] 3. By employing surface hardening treatment, high-reliability fasteners, and a secondary safety structure, this invention can mitigate the drift of clamping connection stiffness and improve long-term service safety.

[0021] 4. By introducing intelligent bolt monitoring and threshold early warning mechanisms, this invention can realize the transformation from periodic maintenance to condition-based predictive maintenance.

[0022] 5. By adopting a modular structure and quick assembly / disassembly design, this invention facilitates installation and replacement under short tunnel nighttime skylight conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the wall-mounted unit structure of the present invention.

[0024] Figure 2This is a schematic diagram of the trackside clamping unit structure of the present invention.

[0025] The corresponding names of the reference numerals in the attached drawings are: 11-outer panel, 12-core layer, 13-ABH thinning region, 14-first damping layer, 15-encapsulation component, 21-first clamp, 22-second clamp, 23-ABH plate, 24-second damping layer. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0027] In this invention, unless otherwise specified, the thickness function In x It is the radial distance measured from the center of energy accumulation or the center of the energy accumulation region outwards. The residual thickness reserved at the center of energy accumulation or the center of an energy accumulation region. This is a scaling factor related to the material and initial thickness. m It is a power exponent, and m ≥2. By making the structural thickness along x As the direction continuously decreases, the phase velocity of the curved wave gradually decreases during propagation, and the energy converges towards the thin end region, i.e., the energy accumulation center or the center of the energy accumulation area, and is converted into heat energy dissipation at the damping layer.

[0028] like Figure 1 As shown, the wall-mounted unit primarily functions along the sound propagation path. Reverberating sound waves within the tunnel act on the outer panel 11, exciting bending vibrations within the unit. As the vibration energy propagates to the ABH thinning zone 13, it gradually converges towards the energy accumulation center due to the thickness gradient effect and is dissipated by the first damping layer 14 covering this area. The core layer 12 can employ a honeycomb structure or an acoustic metamaterial cell structure to balance lightweighting, structural stiffness, and the need for expanded sound absorption bandwidth.

[0029] The periphery of the wall-mounted unit is provided with an encapsulation component 15. The encapsulation component includes a sealing part and a connecting part: the sealing part is composed of weather-resistant sealant and mechanical pressure strip, which is used to improve the long-term durability of the unit in humid and dusty environments; the connecting part adopts a snap-fit ​​or quick-release bolt, which is used to achieve quick assembly and disassembly with the tunnel wall embedded parts or anchor bolts.

[0030] In one specific embodiment, the dimensions of a single wall-mounted unit are 1000 mm × 1000 mm, with a total thickness of 60 mm. The outer panel 11 is made of 1.5 mm thick aluminum alloy plate, the core layer 12 is a regular hexagonal aluminum honeycomb structure with a side length of 30 mm, and the ABH thinning zone 13 has a power-law exponent.m =2.3, residual thickness The first damping layer 14 is made of 2 mm thick butyl rubber damping material.

[0031] like Figure 2 As shown, the railside clamping unit mainly acts at the source of rail vibration. The rail vibration is coupled to the ABH plate 23 through the first clamp 21 and the second clamp 22. The bending wave propagates along the ABH plate 23 to its thin end, i.e., the energy accumulation area, and is dissipated by the second damping layer 24 laid in the energy accumulation area, thereby improving the rail vibration attenuation rate and suppressing structural sound transmission and secondary radiation.

[0032] To improve the long-term stability of the railside clamping connection, the contact surfaces of the first clamp 21 and the second clamp 22 with the rail are preferably treated with surface hardening or friction-enhancing coating. In a preferred embodiment, the contact surfaces are nitrided, with a hardened layer depth of 0.2-0.8 mm, to improve wear resistance and mitigate the preload decay caused by long-term high-frequency vibration.

[0033] The trackside clamping unit is secured using highly reliable fasteners, which can be selected from at least one of double-layer wedge locking washers, all-metal locking nuts, or smart bolts. Additionally, anti-loosening steel wires or anti-fall-off baffles are provided as secondary safety features, creating multiple layers of security. For applications requiring remote monitoring, a preload sensor and wireless transmission module can be integrated into the smart bolt to achieve real-time sensing and data transmission of the tightening status.

[0034] In one specific embodiment, the ABH plate 23 has a length of 280-360 mm, a width of 60-100 mm, a thickness of 5-8 mm at the thick end, and a residual thickness. power exponent m =2.2-2.8; the second damping layer 24 uses a 1.5-3.0 mm thick viscoelastic damping material. Multiple railside clamping units are arranged along the length of the rail, with the spacing between adjacent units being 1-3 times the spacing between rail fasteners.

[0035] The system provided by this invention can be flexibly configured according to the on-site working conditions. For sections with prominent reverberation problems, wall-mounted units can be preferentially arranged on the tunnel sidewalls and arches; for sections with prominent rail vibration and structural sound transmission problems, trackside clamping units can be preferentially arranged along the rails; for comprehensive treatment needs, a combination of both deployment methods can be adopted.

[0036] This invention also provides a maintenance method based on smart bolts, comprising the following steps: first, acquiring real-time or historical preload monitoring data of the smart bolts; then comparing the monitoring data with a preset warning threshold, wherein the warning threshold can be set to 70%-90% of the initial preload; when the preload monitoring data is lower than the warning threshold, the system automatically generates a maintenance work order, wherein the work order includes the location identifier of the unit to be maintained (such as line number, section location, unit number) and suggested maintenance measures (such as torque verification, re-tightening, or unit replacement).

[0037] The modular acoustic black hole energy dissipation unit of this invention can be further designed using a parameterization method to achieve rapid adaptation to different tunnel conditions. This method includes: obtaining basic parameters of the target tunnel section, such as tunnel cross-sectional dimensions, lining type, operating speed, track structure, rail type, fastener spacing, available installation space, and on-site measured noise and vibration spectra; setting performance indicators according to the target frequency band (e.g., 300-1000Hz); and, based on this, determining the geometric dimensions and exponents of the wall-mounted unit and the trackside clamping unit, respectively. m Residual thickness hres The damping layer parameters and spacing were determined, and the design results were verified through finite element simulation or prototype testing.

[0038] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A modular acoustic black hole energy dissipation unit for tunnels, characterized in that, Includes at least one of the following: The wall-mounted unit includes an ABH thinning region (13) with a power-law function thickness distribution and a first damping layer (14) covering the residual thickness region of the energy accumulation center of the ABH thinning region (13). The trackside clamping unit includes a clamping assembly for clamping onto the rail, an ABH plate (23) with a power-law function thickness distribution fixed to the clamping assembly, and a second damping layer (24) laid in the energy accumulation area of ​​the ABH plate (23). The thickness variations of the ABH thinning zone (13) and the ABH plate (23) both follow the relationship... ,in, x It is the radial distance measured from the center of energy accumulation or the center of the energy accumulation region outwards. The residual thickness reserved at the center of energy accumulation or the center of an energy accumulation region. This is a scaling factor related to the material and initial thickness. m It is a power exponent, and m ≥2.

2. The modular acoustic black hole energy dissipation unit according to claim 1, characterized in that, The wall-mounted unit is a multi-layer composite panel structure, which also includes an outer panel (11) as the sound-facing surface and load-bearing structure, an encapsulation component (15) for edge sealing and installation, and a core layer (12) composed of a honeycomb structure or acoustic metamaterial cells disposed between the outer panel (11) and the ABH thinning area (13).

3. The modular acoustic black hole energy dissipation unit according to claim 2, characterized in that, The encapsulation component (15) includes a sealing part and a connecting part; the sealing part includes a weather-resistant sealant and a mechanical pressure strip for pressing the weather-resistant sealant; the connecting part is a quick-release connector for fixing the wall mounting unit to the tunnel wall.

4. The modular acoustic black hole energy dissipation unit according to claim 1, characterized in that, The clamping assembly includes a first clamp (21) and a second clamp (22) used in conjunction, and the contact surface between the clamping assembly and the rail is surface hardened or coated with a friction-enhancing coating.

5. The modular acoustic black hole energy dissipation unit according to claim 4, characterized in that, The surface hardening treatment is nitriding, and the depth of the hardened layer is 0.2-0.8 mm.

6. The modular acoustic black hole energy dissipation unit according to claim 1, characterized in that, The trackside clamping unit is secured by at least one high-reliability fastener, including a double-layer wedge locking washer, an all-metal locking nut, or a smart bolt; when the high-reliability fastener is a smart bolt, the smart bolt integrates a sensor for monitoring preload and a wireless transmission module; the trackside clamping unit also includes an anti-loosening wire or an anti-fall-off baffle as a secondary safety structure.

7. The modular acoustic black hole energy dissipation unit according to claim 1, characterized in that, Power index m Satisfy 2.0≤ m ≤5.0, preferably 2.0≤ m ≤3.5, and residual thickness hres It ranges from 0.5 to 2.0 mm.

8. The modular acoustic black hole energy dissipation unit according to claim 1, characterized in that, The railside clamping units are arranged along the length of the rail, and the spacing between adjacent railside clamping units is an integer multiple of the spacing between rail fasteners, preferably 1-3 times the spacing between rail fasteners.

9. A system comprising the modular acoustic black hole energy dissipation unit according to any one of claims 1-8, for tunnel vibration reduction and noise reduction.

10. A maintenance method for a modular acoustic black hole energy-dissipating unit according to claim 6, characterized in that, Includes the following steps: Acquire real-time or historical preload monitoring data of smart bolts in the trackside clamping unit; The preload monitoring data is compared with a preset warning threshold, which is 70-90% of the initial preload. When the preload monitoring data is lower than the warning threshold, a maintenance work order is generated. The maintenance work order includes at least the location identification information of the trackside clamping unit that needs to be maintained and the recommended maintenance measures.

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