Rail transit wall-attached sound-absorbing layer structure and design method

Abstract

The application discloses a rail transit wall-attached sound-absorbing layer structure and a design method thereof. The sound-absorbing layer structure is composed of three layers of curlable sound-absorbing materials, and is respectively a noise capturing layer, an acoustic corridor layer and a low-frequency suppression layer along the radial direction of a tunnel. A plurality of regular hexagonal micro-porous channel units are arranged in an array on the noise capturing layer. The acoustic corridor layer is provided with staggered cavity corridor structures in an array, so that sound waves are reflected multiple times to convert sound energy into internal energy. The low-frequency suppression layer is provided with arrayed mass concentration units. Due to the difference in density between the arrayed mass concentration units and the film, the vibration of the system composed of the arrayed mass concentration units and the film is opposite, so that the sound-absorbing performance of the whole material is improved. According to the psychoacoustic annoyance degree, the sound-absorbing layer structure can be optimized, so that the design of the sound-absorbing layer structure meets the comfort of drivers and passengers during train driving, prevents work errors of train staff due to hearing insensitivity, and guarantees safe operation of the train.

Description

Technical Field

[0001] This invention relates to the field of rail transit noise control, and is a structure and design method for a wall-mounted sound-absorbing layer in rail transit. Background Technology

[0002] With the rapid development of underground transportation projects such as urban rail transit, subways, and high-speed railways, vehicle-induced reverberation noise in tunnels has gradually become one of the key factors affecting tunnel operation comfort and the quality of the surrounding environment. Vehicle-induced reverberation noise mainly originates from the interaction between the train and the track and tunnel structure during train operation. Especially inside the tunnel, due to the reflection, refraction, and diffraction of sound waves, noise generates continuous reverberation and resonance between the carriage and the tunnel walls, seriously affecting the passenger's riding experience and potentially causing adverse effects on the mechanical equipment inside the tunnel and the surrounding environment.

[0003] Vehicle-induced noise within tunnels is typically low- and mid-frequency. This type of noise has strong penetrating power, especially at high speeds, causing significant loudness and discomfort inside the vehicle, impacting passenger experience and health. Vehicle-induced noise and vibration can also affect the stability of ventilation systems, communication facilities, and other equipment within the tunnel, reducing their lifespan and operational efficiency. Residential and commercial areas outside the tunnel may also be affected by the propagation of tunnel noise, causing noise pollution and impacting the quality of life for nearby residents.

[0004] Currently, effective measures for vehicle-induced reverberation noise in tunnels are not widely available, especially lacking an innovative device capable of absorbing specific dominant frequencies of noise that are more easily perceived by the human ear and adapting to the diverse shapes of tunnel walls. Existing sound-absorbing material technologies, flexible tracks, or floating tracks are inefficient in terms of vibration reduction and noise reduction, and are not targeted at specific dominant frequencies of noise that are more easily perceived by the human ear, making it difficult to meet the growing demand for tunnel noise control. Summary of the Invention

[0005] The purpose of this invention is to develop a novel device and its design method, filling the gap in the current lack of practical applications of this technology. Specifically, it aims to reduce noise at a specific dominant frequency of vehicle-induced reverberation in a certain section of a shield tunnel. This rail transit noise reduction layer structure exhibits good suppression of low-frequency and mid-frequency noise caused by vehicles within the tunnel, while also possessing optimal sound absorption efficiency.

[0006] To achieve the above-mentioned technical objectives of this invention, the invention is implemented through the following technical solutions:

[0007] A sound-absorbing layer structure for rail transit includes three layers of rollable sound-absorbing material, arranged radially into the tunnel wall: a noise-capturing layer, an acoustic corridor layer, and a low-frequency suppression layer.

[0008] The noise capture layer is arrayed with several regular hexagonal microporous channel units;

[0009] The acoustic corridor layer is provided with staggered cavity corridor units, which are the same number as the regular hexagonal microporous channel units and are coaxially connected in series with the regular hexagonal microporous channel units. The staggered cavity corridor units are provided with cavities that can reflect noise multiple times in order to convert acoustic energy into internal energy.

[0010] The low-frequency suppression layer is an elastic film with arrayed mass concentration units. By using the density difference between the arrayed mass concentration units and the elastic film, the system composed of the arrayed mass concentration units and the elastic film vibrates in opposite phase, thereby improving the sound absorption performance of the entire sound-absorbing material layer.

[0011] The geometric data of the sound-absorbing layer structure are obtained through the following formula:

[0012]

[0013] in,

[0014] h is the total thickness of the noise-capturing layer and the acoustic corridor layer, b is the distance between the center points of the arrayed regular hexagonal microporous channel units, r is the radius of the circumscribed circle of the regular hexagonal microporous channel unit, p is the porosity after fitting the optimal sound absorption efficiency data of the noise-capturing layer, and PA' is the improved Zwicker psychoacoustic annoyance level.

[0015] Beneficial effects: This invention can optimize the sound-absorbing layer structure according to the psychoacoustic annoyance level, so that the design of the sound-absorbing layer structure meets the comfort of the driver and passengers during the train operation, prevents the work errors of train staff due to hearing impairment, ensures the safe operation of the train, and protects the physical and mental health of passengers.

[0016] As a further preferred embodiment, the geometry of a single mass concentration unit in the arrayed mass concentration unit is a cone. The radius of the base of the cone and its height are the same as the circumcircle radius of the regular hexagonal microporous channel unit, respectively. The base of the cone is fixed to the elastic film in the same array form as the arrayed regular hexagonal microporous channel unit. The edge of the elastic film is fixed to the tension support frame structure and is tensioned.

[0017] As a further preferred embodiment, each of the staggered cavity corridor units includes a central channel, which is coaxially connected in series with the regular hexagonal microporous channel unit. Multiple staggered cavity corridor units connected to the central channel are staggered along the axial direction of the central channel to form a staggered cavity corridor structure.

[0018] Beneficial effect: Sound waves can be reflected and dissipated multiple times in the staggered cavity corridor structure.

[0019] As a further preferred embodiment, the arrayed mass lumped cells have a density of 6000-11000 kg / m³. 3 Materials that are stable within the range of -40℃ to 45℃ in air.

[0020] Beneficial effects: By utilizing the difference in density between the arrayed mass concentration units and the thin film, the vibration of the system composed of the arrayed mass concentration units and the thin film is out of phase, thereby improving the sound absorption performance of the entire material.

[0021] As a further preferred embodiment, the tensioned support frame structure is made of aluminum, and the shape of the tensioned support frame structure is square. The number of sound-absorbing coupling structure units supported within the range of a single square frame structure is 1-200, and the inner edge distance is 0.5-8mm.

[0022] Beneficial effects: Supporting the arrayed mass concentration unit and the tensioned membrane allows the arrayed mass concentration unit and the membrane to vibrate at a certain frequency, thereby causing the vibration of the system composed of the arrayed mass concentration unit and the membrane to be out of phase, which improves the sound absorption performance of the entire material and can adapt to the diversity of tunnel wall morphology.

[0023] This invention further discloses a design method for the aforementioned rail transit wall-mounted sound-absorbing layer structure, comprising the following steps:

[0024] S1. By collecting noise data in the passenger compartment of the train at speeds of 60km / h, 70km / h and 80km / h, the noise frequency and sound pressure level in the passenger compartment are obtained, thereby obtaining the main frequency of the noise and the corresponding A-weighted sound pressure level.

[0025] S2. The annoyance level is obtained by using the collected binaural noise signals in the passenger compartment of the train car through the psychoacoustic annoyance level calculation method.

[0026] S3. Substitute the obtained annoyance data into the fitting formula based on the optimal sound absorption efficiency data of the noise capture layer to determine the main geometric dimensions of the noise capture layer and the acoustic corridor layer.

[0027] The optimal sound absorption efficiency data fitting formula for the noise capture layer is:

[0028] θ=5+40sin(0.001f), p=0.09tan(0.0005f)+0.001L Aeq ,in,

[0029] θ is the aperture angle, p is the aperture ratio, f is the dominant frequency of the noise, and L is the aperture ratio. Aeq The A-weighted sound pressure level is the frequency of the noise.

[0030] Beneficial effects: The design method described in this invention determines the main geometric design parameters of the device by obtaining the noise frequency and sound pressure level inside the train and the annoyance level of the noise, thereby enabling targeted absorption of the main frequency of the noise.

[0031] As a further preferred embodiment, the dominant frequency f of the noise is taken as the frequency at which the A-weighted sound level reaches its maximum value in the noise data acquisition results.

[0032] Beneficial effect: The main frequency f of the noise is taken as the frequency at which the A-weighted sound level reaches its maximum value in the noise data acquisition results. This can specifically improve the absorption efficiency of noise frequency bands that are more easily perceived by the human ear.

[0033] As a further preferred embodiment, in step S2, the method for calculating psychoacoustic annoyance level involves using the binaural signals of noise inside the carriage obtained by the artificial head data acquisition system, and calculating the A-weighted sound pressure level L of each sound sample using ArtemiS10.00 software. Aeq The noise level (N) and loudness (F) data are used to calculate the noise level based on the improved Zwicker psychoacoustic annoyance formula.

[0034] The improved Zwicker psychoacoustic annoyance calculation formula is as follows:

[0035]

[0036] In the above formula: PA' is the improved Zwicker psychoacoustic annoyance level, N5 is the cumulative percentage loudness, S is the sharpness, F is the vibrato, R is the roughness, T is the tone modulation, and w s For the weighting coefficients related to sharpness, w FR Weighting coefficients related to slope F and roughness R, w T These are the weighting coefficients related to tone scheduling.

[0037] Beneficial effects: The formula uses three correction factors w. s w FR w T The basic loudness N5 is weighted and corrected to more accurately reflect the psychological response of humans to complex sounds. This model combines multiple psychoacoustic parameters and is closer to the subjective auditory experience of the human ear. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the sound-absorbing layer structure and its sound-absorbing coupling structure unit and principle of the present invention;

[0039] Figure 2 This is a schematic diagram of the noise capture layer of the present invention;

[0040] Figure 3 This is a structural schematic diagram of the staggered cavity corridor unit of the present invention;

[0041] Figure 4 This is an axial cross-sectional view of a staggered cavity corridor unit;

[0042] Figure 5 This is a schematic diagram of the low-frequency suppression layer of the present invention;

[0043] Figure 6 This is a schematic diagram of the sound-absorbing coupling structure of the present invention;

[0044] Figure 7 This is a schematic diagram of the arrangement of in-vehicle noise measurement points according to a specific embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram of the in-vehicle noise test site according to a specific embodiment of the present invention;

[0046] Figure 9 This is a fitted image of the optimal sound absorption efficiency of the noise capture layer geometry design of the present invention;

[0047] The structure includes: 1. Noise-absorbing layer; 2. Noise-capturing layer; 3. Acoustic corridor layer; 4. Low-frequency suppression layer; 5. Noise-absorbing coupling structure unit; 6. Regular hexagonal microporous channel unit; 7. Staggered cavity corridor unit; 7-1. Central channel; 7-2. Cavity; 8. Arrayed mass concentration unit; 9. Elastic membrane; 10. Tensioned support frame structure. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0049] Example 1:

[0050] This implementation example is a wall-mounted sound-absorbing layer structure for rail transit. For example... Figure 1 As shown. The sound-absorbing layer structure comprises three acoustic layers: a noise-capturing layer, an acoustic corridor layer, and a low-frequency suppression layer. This sound-absorbing layer structure is fabricated according to the target structural parameters determined by the sound-absorbing layer structure design method described below.

[0051] A study was conducted on the in-car noise characteristics of trains operating in a tunnel environment on a specific section of a domestic railway line. Measurement points were arranged in the middle of the passenger compartment. The locations of the acoustic measurement points are as follows: Figure 6 As shown, the measuring point inside the vehicle is located 1.2m above the floor. The on-site conditions for the vehicle interior noise test are as follows. Figure 7As shown, the noise signal was acquired using the Danish B&KLANXI data acquisition and analysis system, and tested using a 50-channel spherical acoustic array. The 1 / 3 octave band spectrum of the train noise at the operating speed in the section was obtained, from which the main frequency of the noise was found to be 850Hz, corresponding to an A-weighted sound pressure level of 72.3dB. The data was then substituted into the optimal sound absorption efficiency data fitting formula of the noise capture layer.

[0052] The optimal sound absorption efficiency formula for the noise-capturing layer is derived from numerical calculations performed on the noise-capturing layer within a thickness design range of 5mm-20mm under different opening angles and opening ratios. This calculations are based on the noise-capturing layer's characteristic of enhancing low-frequency sound absorption while weakening high-frequency sound absorption compared to non-perforated panels. The optimal opening angle and opening ratio for sound absorption at different noise dominance frequencies are as follows: Figure 8 As shown, the optimal sound absorption efficiency data fitting formula for the noise-capturing layer is obtained by fitting the data:

[0053] θ=5+40sin(0.001f), p=0.09tan(0.0005f)+0.001L Aeq1

[0054] In the above formula: θ is the opening angle, p is the opening ratio, f is the dominant frequency of the noise, and L... Aeq The A-weighted sound pressure level is the frequency of the noise.

[0055] Simultaneously, a data acquisition system using an artificial head was employed at a measurement point in the middle of the train carriage to collect binaural signal sound samples. The A-weighted sound pressure level L of the sound samples was calculated using ArtemiS10.00 software. Aeq2 The noise level is calculated by taking into account factors such as loudness (N), jitter (F), roughness (R), sharpness (S), and tone modulation (T), and then using the improved Zwicker psychoacoustic annoyance calculation formula.

[0056] Among them, the noise evaluation value of the binaural signals obtained using the artificial head data acquisition system is usually calculated using the following formula:

[0057]

[0058] In the above formula: L s For sound sample sound level, L L For the left ear sound level, L R The sound level is for the right ear.

[0059] The improved Zwicker psychoacoustic annoyance calculation formula includes the following formula:

[0060]

[0061] In the above formula: PA' is the improved Zwicker psychoacoustic annoyance level, N5 is the cumulative percentage loudness, S is the sharpness, F is the tremolo, R is the roughness, and T is the tone modulation.

[0062] Based on the above data, the geometric design values ​​for the sound-absorbing layer structure can be obtained: opening angle θ = 35°, opening ratio p = 11%, and total thickness of the noise-capturing layer and acoustic corridor layer. Hole spacing The radius of the circumcircle of the perforated hexagons arranged in a square pattern

[0063] The shield tunnel has an inner diameter of 5500mm. The axial length of the sound-absorbing layer structure laid on both sides of the inner wall of the shield tunnel is 38500mm, and the circumferential length of the layer laid on one side along the bottom of the track bed is 4600mm.

[0064] The sound-absorbing layer structure 1 consists of a noise-capturing layer 2, an acoustic corridor layer 3, and a low-frequency suppression layer 4, which are arranged radially into the tunnel wall. The noise-capturing layer 2 is provided with arrayed regular hexagonal microporous channel units 6, which are used to conduct noise to the acoustic corridor layer 3 and the low-frequency suppression layer 4. The acoustic corridor layer 3 is provided with staggered cavity corridor units 7 for absorbing noise. The low-frequency suppression layer 4 is provided with arrayed mass concentration units 8, an elastic membrane 10, and a tensioned support frame structure 11.

[0065] Among them, the arrayed regular hexagonal microporous channel unit 6, the staggered cavity corridor unit 7 and the arrayed mass concentration unit 8 on the sound-absorbing layer structure are combined to form the sound-absorbing coupling structure unit 5.

[0066] The noise-capturing layer 2 is composed of a melamine foam porous sound-absorbing material sheet with openings. The opening method is an array of regular hexagonal microporous channel units 6 with an opening rate of about 11% and a thickness of 5mm for the porous sound-absorbing material sheet. The array of regular hexagonal microporous channel units 6 has a regular hexagonal opening shape, with a radius of 2.5mm for the outer circle of the regular hexagon near the tunnel wall and an opening angle of 35°.

[0067] The acoustic corridor layer 3 is formed by opening a thin sheet of porous melamine foam sound-absorbing material. The opening method is staggered cavity corridor unit 7 with an opening rate of about 11% and a thickness of 5mm for the porous sound-absorbing material thin sheet. Each staggered cavity corridor unit 7 includes a central channel 7-1, which is coaxially connected to the regular hexagonal microporous channel unit. Multiple cavities 7-2 connected to the central channel 7-1 are staggered along the axial direction of the central channel 7-1 to form a staggered cavity corridor structure.

[0068] The low-frequency suppression layer 4 consists of arrayed mass concentration units 8, an elastic film 10, and a tensioned support frame structure 11. The arrayed mass concentration units 8 are stainless steel cones with their bottom surfaces adhered to the film; the radius of the base circle is 2.5 mm, and the cone height is 2.5 mm. The elastic film 10 is a 0.2 mm thick polyethylene film. The tensioned support frame structure 11 has a density of 2800 kg / m³. 3 The square aluminum frame supports 100 sound-absorbing coupling structural units 5 within the structural range of a single square aluminum frame, with an inner edge distance of 4mm.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sound-absorbing layer structure for rail transit, comprising three rollable sound-absorbing material layers, which are arranged sequentially along the radial direction of the tunnel wall: a noise-capturing layer (2), an acoustic corridor layer (3), and a low-frequency suppression layer (4), wherein, The noise capture layer (2) is arranged with several regular hexagonal microporous channel units (6). The acoustic corridor layer (3) is provided with staggered cavity corridor units (7) that are the same number as the regular hexagonal microporous channel units (6) and are coaxially connected in series with the regular hexagonal microporous channel units (6). The staggered cavity corridor units (7) have cavities that can reflect noise multiple times in order to convert sound energy into internal energy. The low-frequency suppression layer (4) is an elastic film (10) with arrayed mass concentration units. By the difference in density between the arrayed mass concentration units and the elastic film, the system composed of the arrayed mass concentration units and the elastic film (10) vibrates in opposite phase, thereby improving the sound absorption performance of the entire sound-absorbing material layer. The geometric data of the sound-absorbing layer structure are obtained through the following formula: ； ； ,in, h is the total thickness of the noise-capturing layer and the acoustic corridor layer, b is the distance between the center points of the arrayed regular hexagonal microporous channel units, r is the radius of the circumscribed circle of the regular hexagonal microporous channel unit, p is the porosity after fitting the optimal sound absorption efficiency data of the noise-capturing layer, and PA' is the improved Zwicker psychoacoustic annoyance level.

2. The sound-absorbing layer structure for rail transit walls according to claim 1, characterized in that, The geometry of a single mass concentration unit in the arrayed mass concentration unit (8) is a cone. The radius of the bottom surface and the height of the cone are the same as the circumcircle radius of the regular hexagonal microporous channel unit (6). The bottom surface of the cone is fixed on the elastic film (10) in the same array form as the arrayed regular hexagonal microporous channel unit (6). The edge of the elastic film (10) is fixed on the tension support frame structure (11) and is tensioned.

3. The sound-absorbing layer structure for rail transit walls according to claim 1, characterized in that, Each of the staggered cavity corridor units (7) includes a central channel, which is coaxially connected to the regular hexagonal microporous channel unit (6). Multiple staggered cavity corridor units connected to the central channel are staggered along the axial direction of the central channel to form a staggered cavity corridor structure.

4. The wall-mounted sound-absorbing layer structure for rail transit according to claim 1, characterized in that, The arrayed mass lumped cells (8) have a density of 6000-11000 kg / m³. 3 Materials that are stable within the range of -40°C to 45°C in air.

5. The wall-mounted sound-absorbing layer structure for rail transit according to claim 2, characterized in that, The tensioned support frame structure (11) is made of aluminum and is square in shape. The number of sound-absorbing coupling structure units (5) supported within the range of a single square frame structure is 1-200, and the inner edge distance is 0.5-8mm.

6. A design method for a wall-mounted sound-absorbing layer structure for rail transit as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. By collecting noise data in the passenger compartment of the train at speeds of 60km / h, 70km / h and 80km / h, the noise frequency and sound pressure level in the passenger compartment are obtained, thereby obtaining the main frequency of the noise and the corresponding A-weighted sound pressure level. S2. The annoyance level is obtained by using the collected binaural noise signals in the passenger compartment of the train car through the psychoacoustic annoyance level calculation method. S3. Substitute the obtained annoyance data into the fitting formula of the optimal sound absorption efficiency data of the noise capture layer to determine the main geometric dimensions of the noise capture layer (2) and the acoustic corridor layer (3); The optimal sound absorption efficiency data fitting formula for the noise capture layer is: , ,in, θ is the aperture angle, p is the aperture ratio, f is the dominant frequency of the noise, and L is the aperture ratio. Aeq The A-weighted sound pressure level is the frequency of the noise.

7. The design method according to claim 6, characterized in that, The dominant frequency f of the noise is taken as the frequency at which the A-weighted sound pressure level reaches its maximum value in the noise data acquisition results.

8. The design method according to claim 6, characterized in that, In step S2, the psychoacoustic annoyance level calculation method involves obtaining binaural signals of noise inside the carriage using an artificial head data acquisition system, and calculating the A-weighted sound pressure level L of each noise sample using ArtemiS10.00 software. Aeq The noise level (N) and loudness (F) data are used to calculate the noise level based on the improved Zwicker psychoacoustic annoyance formula. The improved Zwicker psychoacoustic annoyance calculation formula is as follows: 、 、 、 ； In the above formula: N5 is the cumulative percentage loudness, S is the sharpness, F is the vibrato, R is the roughness, T is the tone modulation, and w s For the weighting coefficients related to sharpness, w FR Weighting coefficients related to jitter F and roughness R, w T These are the weighting coefficients related to tone scheduling.

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