Method for testing and improving noise attenuation performance of road surface in highway tunnel

Abstract

The application provides a highway tunnel pavement noise attenuation performance test and low noise modification method, and the test method comprises the following steps: arranging a noise test system according to a set point, and testing the cross-section reverberation time and the longitudinal section longitudinal attenuation rate before and after pavement modification respectively; wherein the sound source is arranged above the road center line, a plurality of cross-section sound pressure collection units are arranged on the cross-section of the sound source, and a plurality of groups of longitudinal section sound pressure collection units are arranged on the longitudinal section of the sound source along one side of the sound source; according to the average value T 60 of the reverberation time and the average value R of the longitudinal attenuation rate, the pavement noise attenuation performance is evaluated. The test method in the application can obtain the reverberation time and the longitudinal attenuation rate in the tunnel, evaluate the degree of noise interference on the driver and the passenger, and clearly define the test point arrangement position, so that the test result is more targeted, and the result error caused by too few test points or test point arrangement and other human factors is avoided.

Description

Technical Field

[0001] This invention relates to the field of noise reduction performance testing technology, and in particular to a method for testing the road surface noise attenuation performance in highway tunnels and for low-noise retrofitting. Background Technology

[0002] With the rapid development of cities and the improvement of people's living standards, the number of cars is increasing, and highway engineering has developed rapidly. At the same time, highway tunnels, especially extra-long tunnels, are also becoming more and more common, and traffic noise pollution in tunnels has attracted increasing attention. At present, in the field of municipal construction under the concept of green environmental protection, new demands have been put forward for road surface noise reduction functions, and various road surface noise reduction technologies have been rapidly developed, promoted and applied. Among them, laying noise-reducing materials or adopting noise-reducing pavement structures in tunnels is a commonly used road surface noise reduction technology. For example, Chinese patent document CN105714638B discloses a rubber tire particle noise-reducing pavement, which consists of five parts: a stabilized crushed stone base layer, a WRAC-N wet-mixed rubber asphalt concrete lower layer, a DRAC-n dry-mixed rubber asphalt concrete upper layer, a lower layer, a rubber asphalt waterproof bonding layer added between the upper and lower layers, and a rubber asphalt stress-absorbing layer added to the upper layer. For example, Chinese patent document CN214497046U discloses an anti-skid and noise-reducing pavement containing a Novachip ultrathin wear layer, which includes a stress-absorbing layer, a lower layer, a middle layer, an upper layer and a Novachip ultrathin wear layer laid from bottom to top.

[0003] After the noise-reducing pavement inside the tunnel is constructed, its noise reduction effect needs to be tested and evaluated. Currently, the main method for evaluating the noise reduction effect of the pavement inside the tunnel is sound pressure level testing. This involves setting up noise testing devices on both sides of the pavement to measure the sound pressure level and thus evaluate the noise situation inside the tunnel. However, in practical applications, this testing and evaluation method has several problems. Firstly, the primary noise sufferers inside the tunnel are drivers and passengers, and testing noise on the roadside cannot accurately represent the experience of drivers and passengers traveling in the lane. Secondly, the placement of measuring points is not clearly defined, and testing relies on experience, making the measurement results highly susceptible to human error. If there are too few measuring points or the placement is unreasonable, effective data cannot be obtained, hindering an effective evaluation of the noise-reducing pavement. Furthermore, the placement height of the sound pressure acquisition units is not clearly defined; the human ear is the primary organ for receiving noise, and the height of the ear is the most important location in the sound field to consider.

[0004] Meanwhile, at present, there is no basis for the application of noise-reducing pavement materials or structures in tunnels. Designers and construction companies simply apply standard drawings based on experience without making matching modifications to meet noise reduction needs. As mentioned earlier, regarding the effectiveness of low-noise modifications, only sound pressure levels are tested on the roadside, and the magnitudes of sound pressure levels before and after the modifications are simply compared, without a quantitative scoring and grading method system. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, this invention provides a method for testing the noise attenuation performance of road surfaces in highway tunnels and for low-noise retrofitting. This method can test and evaluate the noise attenuation patterns of road surfaces within tunnels, offering comprehensive testing, high precision, and accurate evaluation. Furthermore, for road surfaces that fail to meet noise standards, a low-noise retrofitting method is proposed, effectively reducing noise levels within tunnels and improving the noise environment.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A method for testing the noise attenuation performance of road surface in a highway tunnel includes the following steps: (1) Arranging a noise testing system according to the set points, and testing the cross-sectional reverberation time and longitudinal attenuation rate of the road surface respectively; the noise testing system includes a sound source and a sound pressure acquisition unit, wherein the sound source is arranged above the centerline of the road, and multiple cross-sectional sound pressure acquisition units are arranged on the cross-section of the sound source, and multiple sets of longitudinal sound pressure acquisition units are arranged sequentially on the longitudinal section of the sound source along one side of the sound source; in the horizontal direction, the spacing between each two adjacent sets of longitudinal sound pressure acquisition units is equal;

[0008] The method for testing the cross-sectional reverberation time is as follows: turn on the sound source to output a stable sound pressure level, the sound source emits pink noise continuously at a frequency of 63-10kHz; turn off the sound source, use the arranged cross-sectional sound pressure acquisition units to collect the noise attenuation signal measured after the sound source is interrupted, plot the noise attenuation curve, and calculate the average reverberation time of multiple cross-sectional sound pressure acquisition units.

[0009] The test method for the longitudinal attenuation rate of the longitudinal section includes: turning on the sound source to output a stable sound pressure level, with the sound source emitting a frequency of 63-10kHz, and continuously emitting pink noise; using the arranged longitudinal section sound pressure acquisition units to acquire the noise attenuation signal measured under a steady-state sound field, calculating the longitudinal attenuation rate per unit distance between each pair of adjacent longitudinal section sound pressure acquisition units and calculating the average value, thereby obtaining the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units.

[0010] (2) The road noise attenuation index (NAI) is calculated according to the following formula:

[0011]

[0012] Among them, T 60 R is the average reverberation time value of the multiple cross-sectional sound pressure acquisition units obtained in step (1), in seconds; R is the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units, in dB / m.

[0013] (3) The noise reduction performance of the road surface is evaluated based on the Road Noise Attenuation Index (NAI).

[0014] In step (3), the noise reduction performance of the road surface is evaluated. When 90 < NAI ≤ 100, the evaluation result is excellent; when 80 < NAI ≤ 90, the evaluation result is good; when 70 < NAI ≤ 80, the evaluation result is average; when 60 < NAI ≤ 70, the evaluation result is second best; when 0 < NAI ≤ 60, the evaluation result is poor.

[0015] When testing the cross-sectional reverberation time and longitudinal attenuation rate, the sound pressure level output by the sound source remained stable at 100 dB.

[0016] Reverberation time T of each cross-sectional sound pressure acquisition unit 60i The calculation method is as follows:

[0017]

[0018] Among them, L′ i L i L′ represents the sound pressure level attenuation values ​​measured sequentially after the sound source is turned off. i =25dB, L i =5dB,t i ′ and t i L′ i and L i The test time corresponding to the sound pressure level, i = 1, 2...n, where n is the total number of cross-sectional sound pressure acquisition units.

[0019] The sound source is positioned above the centerline of the road surface inside the highway tunnel, at a height of 0.6m above the road surface. The cross-sectional sound pressure acquisition unit is positioned on the cross-section of the sound source, with two points each above the centerline, above the centerline of the half of the road surface located on one side of the centerline, and above the edge line of the half of the road surface. The heights of the two points are 1.2m and 2.6m, respectively.

[0020] Multiple sets of longitudinal profile sound pressure acquisition units are set up on one side of the sound source. The horizontal distance between any two adjacent sets of longitudinal profile sound pressure acquisition units is 30 meters. The horizontal distance between the longitudinal profile sound pressure acquisition unit closest to the sound source and the sound source is also 30 meters. The distance between the longitudinal profile sound pressure acquisition unit closest to the tunnel entrance and the tunnel entrance is greater than or equal to 30 meters. Each longitudinal profile sound pressure acquisition unit has two points set above the centerline of the road, with heights of 1.2 meters and 2.6 meters respectively.

[0021] A method for low-noise road surface modification in a highway tunnel includes the following steps: (1) Arranging a noise testing system according to the set points, and testing the cross-sectional reverberation time and longitudinal attenuation rate of the road surface to be modified respectively; the noise testing system includes a sound source and a sound pressure acquisition unit, wherein the sound source is arranged above the centerline of the road, and multiple cross-sectional sound pressure acquisition units are arranged on the cross-section of the sound source, and multiple sets of longitudinal sound pressure acquisition units are arranged sequentially on the longitudinal section of the sound source along one side of the sound source; in the horizontal direction, the spacing between each two adjacent sets of longitudinal sound pressure acquisition units is equal; wherein the method for testing the cross-sectional reverberation time is as follows: turn on the sound source to output a stable sound pressure level, the sound source emits a frequency of 63-10kHz, and continuously emits pink noise; turn off the sound source, use the arranged cross-sectional sound pressure acquisition units to collect the noise attenuation signal measured after the sound source is interrupted, draw the noise attenuation curve, and calculate the average reverberation time T of multiple cross-sectional sound pressure acquisition units. 60 ;

[0022] The test method for the longitudinal attenuation rate of the longitudinal section includes: turning on the sound source to output a stable sound pressure level, with the sound source emitting a frequency of 63-10kHz, and continuously emitting pink noise; using the arranged longitudinal section sound pressure acquisition units to acquire the noise attenuation signal measured under the steady-state sound field, calculating the longitudinal attenuation rate per unit distance between each pair of adjacent longitudinal section sound pressure acquisition units and calculating the average value, to obtain the average value R of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units.

[0023] (2) The road noise attenuation index (NAI) is calculated according to the following formula:

[0024]

[0025] Among them, T 60 R is the average reverberation time value of the multiple cross-sectional sound pressure acquisition units obtained in step (1), in seconds; R is the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units, in dB / m.

[0026] (3) The road surface is modified to be low-noise based on the road noise attenuation index (NAI). When 80 < NAI ≤ 90, the modified road surface is paved with at least one layer of large-void asphalt; when 70 < NAI ≤ 80, the modified road surface is paved with at least two layers of large-void asphalt; when NAI ≤ 70, the modified road surface is paved with at least two layers of large-void asphalt, of which at least one layer is a high-damping large-void asphalt layer.

[0027] The method for low-noise road surface reconstruction in highway tunnels involves testing the noise attenuation performance of the reconstructed road surface using the same testing method as the road surface to be reconstructed. The calculated NAI value of the reconstructed road surface after testing is greater than or equal to 90.

[0028] The large-void asphalt layer is a low-noise pavement layer with a porosity greater than or equal to 18%, and the high-damping large-void asphalt layer is a low-noise pavement layer with a porosity greater than or equal to 18% and a damping ratio greater than or equal to 40%.

[0029] When the large-void asphalt layer is used as the surface layer, its nominal maximum aggregate size is any one of 4.75mm, 9.5mm, 13.2mm, and 16mm, and its thickness is 1cm to 5cm; when the large-void asphalt layer is used as the lower layer, its nominal maximum aggregate size is any one of 13.2mm, 16mm, 19mm, and 26.5mm, and its thickness is 2.5cm to 8cm.

[0030] The mixture of the large-void asphalt layer contains an elastic component, which is at least one of rubber powder, rubber particles, and polyurethane; or, the porosity of the large-void asphalt layer is greater than or equal to 25%.

[0031] The method for testing the road surface noise attenuation performance and for low-noise retrofitting in highway tunnels as described in this invention has the following advantages:

[0032] The method for testing the noise attenuation performance of road surfaces in highway tunnels as described in this invention uses a noise testing system to obtain cross-sectional and longitudinal noise signals of the road surface under test within the tunnel. It calculates the reverberation time and longitudinal attenuation rate, and establishes a noise attenuation index (NAI) that comprehensively considers both indicators, thereby determining the noise attenuation performance of the road surface under test. Simultaneously testing the noise attenuation performance of both cross-sections and longitudinal sections, compared to roadside noise testing methods, allows for a more comprehensive assessment of the acoustic environment by specifically analyzing the unique noise reverberation and slow decay phenomena within tunnels based on the comprehensive index NAI.

[0033] As a semi-enclosed or enclosed (long tunnel) spatial environment, tunnels experience multiple reflections of noise generated by vehicles as it propagates through the road surface and tunnel walls. This sound wave overlap leads to reverberation, and the rate of noise attenuation decreases due to the reverberation effect during longitudinal propagation. Compared to open areas outside the tunnel, noise levels inside the tunnel are significantly higher, and the longer reverberation time results in poor sound clarity. The road surface also absorbs noise during propagation, accelerating sound wave energy attenuation and shortening the reverberation time. To quantitatively evaluate the noise attenuation performance of the road surface within a tunnel, this invention proposes an original calculation model for the Noise Attenuation Index (NAI), and the model parameters for NAI have been determined through extensive experimental statistical analysis. NAI is negatively correlated with reverberation time and positively correlated with the longitudinal attenuation rate. That is, a higher NAI score indicates a shorter reverberation time or a larger longitudinal attenuation rate, suggesting higher sound clarity and faster noise attenuation within the tunnel, thus resulting in a superior sound field environment.

[0034] Currently, noise levels are used to evaluate noise conditions within tunnels. However, due to the lack of noise emission standards, the severity of the noise cannot be clearly perceived. This invention assigns a percentage score to the Noise Attenuation Index (NAI) and provides a criterion for determining the rating level, enabling accurate assessment of noise severity.

[0035] Evaluation indicators excellent good middle Second-rate Difference NAI (90,100] (80,90] (70,80] (60,70] (0,60] T60 / R (0,20] (20,36.4] (36.4,47.2] (47.2,56.0] (56,+∞]

[0036] Meanwhile, compared with the testing and evaluation methods in the prior art, the testing method in this application determines the layout scheme of the sound pressure acquisition unit and tests the noise at heights of 1.2m and 2.6m, which is more consistent with the ear height of drivers and passengers in buses and trucks. This method can obtain more effective results, avoid the result error caused by human factors such as too few measurement points or the arrangement of measurement points, and can truly evaluate the impact of noise in the tunnel on the audience (i.e., drivers and passengers).

[0037] The low-noise road surface reconstruction method for highway tunnels described in this invention is based on a noise attenuation performance testing method, using the noise attenuation index to guide the reconstruction of the road surface. A suitable reconstruction scheme is selected based on the measurement results of the road surface to be reconstructed. Specifically, when 80 < NAI ≤ 90, the reconstructed road surface is paved with at least one layer of high-voidity asphalt; when 70 < NAI ≤ 80, the reconstructed road surface is paved with at least two layers of high-voidity asphalt; when NAI ≤ 70, the reconstructed road surface is paved with at least two layers of high-voidity asphalt, of which at least one layer is a high-damping high-voidity asphalt layer. The reconstruction scheme is used to design the reconstructed road surface and provides control standards for low-noise reconstruction, ensuring that the noise attenuation performance of the reconstructed road surface meets the noise reduction requirements within the tunnel, providing a scientific basis for noise-reducing road surface design.

[0038] To make the technical solution of the method for testing the road surface noise attenuation performance and low-noise retrofitting in highway tunnels described in this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Detailed Implementation Attached Figure Description

[0040] like Figure 1 The diagram shows the distribution of the cross-sectional sound pressure acquisition unit according to the present invention.

[0041] like Figure 2 The figure shows the noise attenuation curve plotted based on the noise attenuation signal according to the present invention. The horizontal axis represents time in seconds, and the vertical axis represents the sound pressure level attenuation value in dB.

[0042] like Figure 3 The diagram shows the distribution of the longitudinal section sound pressure acquisition unit according to the present invention.

[0043] The attached figures are labeled as follows:

[0044] 1-Tunnel; 11-Road surface inside the tunnel; 2-Cross-section sound pressure acquisition unit; 3-Longitudinal-section sound pressure acquisition unit. Detailed Implementation

[0045] Example 1

[0046] This invention uses a certain No. 1 tunnel as an example to illustrate the method for testing the road surface noise attenuation performance in a highway tunnel according to this application. A noise testing system is arranged at predetermined points inside tunnel 1 to test the cross-sectional reverberation time and longitudinal attenuation rate. In this embodiment, the sound source is located at the centerline of the highway inside the tunnel, 0.6m above the ground. The sound source consists of a loudspeaker, a power amplifier, and a signal generator. Multiple cross-sectional sound pressure acquisition units 2 are arranged on the cross-section of the sound source, such as... Figure 1 As shown, multiple cross-sectional sound pressure acquisition units 2 are located on the same side of the road centerline. Specifically, two points are set above the road centerline inside the tunnel, above the centerline of the half-width road surface located on one side of the road centerline, and above the edge line of the half-width road surface. The heights of the two points are 1.2m and 2.6m, respectively. A total of 6 cross-sectional sound pressure acquisition units are set.

[0047] In this embodiment, the method for calculating the cross-sectional reverberation time is as follows: The sound source is turned on to output a stable sound pressure level of 100 dB. The sound source's frequency is 63-10 kHz, continuously emitting pink noise. The sound source is then turned off, and the noise attenuation signal measured after the sound source is interrupted is acquired using the arranged cross-sectional sound pressure acquisition unit. The sound energy density is converted into sound pressure level, and a noise attenuation curve is plotted. Figure 2 As shown, the reverberation time T of each cross-sectional sound pressure acquisition unit is calculated. 60i The calculation formula is as follows:

[0048]

[0049] Among them, L′ i L i The values ​​are the sound pressure level attenuation values ​​measured sequentially after the sound source was turned off, with values ​​of 25 dB and 5 dB respectively; t i ′ and t i L′ i and L i The test time corresponding to the sound pressure level, i = 1, 2...6. Calculate the reverberation time T of each cross-sectional sound pressure acquisition unit. 60i Then, the average value of the reverberation time T is obtained by taking the average value. 60 .

[0050] Tunnel No. 1 has a dense-graded pavement with a pavement structure of 4cm SMA-13 ​​upper layer + 6cm AC-20 lower layer. The specific test results of the reverberation time are shown in Table 1.

[0051] Table 1. Reverberation time of a certain No. 1 tunnel (unit: seconds)

[0052]

[0053] Multiple sets of longitudinal section sound pressure acquisition units are arranged sequentially along one side of the sound source on the longitudinal section: such as Figure 3 As shown, in the horizontal direction, the spacing between any two adjacent sets of longitudinal profile sound pressure acquisition units is equal. In this embodiment, four sets of longitudinal profile sound pressure acquisition units are set on one side of the sound source. The horizontal spacing between any two adjacent sets of longitudinal profile sound pressure acquisition units is 30 meters. The distances from the four sets of longitudinal profile sound pressure acquisition units to the sound source are 30m, 60m, 90m, and 120m, respectively. The horizontal distance between the longitudinal profile sound pressure acquisition unit closest to the sound source and the sound source is also 30 meters. Each set of longitudinal profile sound pressure acquisition units has two sound pressure acquisition units, which are arranged at 1.2m and 2.6m above the road surface, respectively. To avoid the influence of the boundary effect at the tunnel entrance, in this embodiment, the distance between the longitudinal profile sound pressure acquisition unit closest to the tunnel entrance and the tunnel entrance / exit is greater than 30m.

[0054] The method for testing the longitudinal attenuation rate of the longitudinal section in this embodiment includes: turning on the sound source to output a stable sound pressure level of 100dB, with the sound source's emission frequency being 63-10kHz, and continuously emitting pink noise; using the arranged longitudinal section sound pressure acquisition units to acquire the noise attenuation signal measured under a steady-state sound field, calculating the longitudinal attenuation rate per unit distance between each pair of adjacent longitudinal section sound pressure acquisition units, and further calculating the average value to obtain the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units; wherein the method for calculating the longitudinal attenuation rate per unit distance between each pair of adjacent longitudinal section sound pressure acquisition units is as follows: subtracting the sound pressure level data acquired by the upstream pair of longitudinal section sound pressure acquisition units from the sound pressure level data acquired by the downstream pair of longitudinal section sound pressure acquisition units to obtain the longitudinal attenuation value of the two adjacent pairs of longitudinal section sound pressure acquisition units, and dividing the longitudinal attenuation value by the horizontal distance between the two adjacent pairs of longitudinal section sound pressure acquisition units to obtain the longitudinal attenuation rate per unit distance. In this context, upstream and downstream refer to the horizontal distance between the source and the sound source. The direction closer to the sound source in the horizontal direction is upstream, and the direction farther away is downstream.

[0055] In this embodiment, each sound pressure acquisition unit consists of a sound pressure sensor.

[0056] Tunnel No. 1 has a dense-graded pavement with a pavement structure of a 4cm SMA-13 ​​upper layer and a 6cm AC-20 lower layer. The specific test results of the longitudinal attenuation rate are shown in Table 2. The sound pressure level data collected by each longitudinal section sound pressure acquisition unit is the average of the measurement results of the two sound pressure acquisition units in that group.

[0057] Table 2. Longitudinal Attenuation Rate of Tunnel No. 1

[0058]

[0059] The road noise attenuation index (NAI) is calculated using the following formula:

[0060]

[0061] Among them, T 60 R is the average reverberation time value of the multiple cross-sectional sound pressure acquisition units obtained in step (1), in seconds; R is the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units, in dB / m.

[0062] The noise attenuation performance of a certain tunnel No. 1 is calculated as shown in Table 3.

[0063] Table 3 Noise Attenuation Performance of Tunnel No. 1

[0064]

[0065] Example 2

[0066] This invention uses a No. 2 tunnel as an example to illustrate the method for testing the road surface noise attenuation performance in highway tunnels. The noise testing system, layout, and testing method in this embodiment are exactly the same as in Embodiment 1. The No. 2 tunnel in this embodiment has a dense-graded pavement with a pavement structure of a 4cm SMA-13 ​​upper layer + a 6cm AC-20 lower layer. The specific test results for reverberation time are shown in Table 4, and the specific test results for longitudinal attenuation rate per unit distance are shown in Table 5. The calculated noise attenuation performance of the No. 2 tunnel is shown in Table 6.

[0067] Table 4. Reverberation time of a certain No. 2 tunnel (unit: seconds)

[0068]

[0069] Table 5. Longitudinal attenuation rate of a certain No. 2 tunnel (unit: dB / m)

[0070]

[0071] Table 6 Noise Attenuation Performance of Tunnel No. 2

[0072]

[0073] Example 3

[0074] This embodiment uses Tunnel No. 1 from Embodiment 1 as an example to illustrate the low-noise road surface modification method for highway tunnels described in this invention. Test results in Embodiment 1 show that the noise reduction performance of this tunnel is 70 < NAI ≤ 80, with a medium rating. To achieve a better noise reduction effect, at least two layers of high-void asphalt are laid on the modified road surface. Therefore, the 4cm SMA-13 ​​upper layer and 6cm AC-20 lower layer of this tunnel are replaced with 4cm PAC-13 high-void asphalt upper layer and 6cm PAC-13 high-void asphalt lower layer, respectively. The porosity of the 4cm PAC-13 high-void asphalt upper layer is 20%, and the porosity of the 6cm PAC-13 high-void asphalt lower layer is 22%.

[0075] The noise attenuation performance of the road surface inside the modified highway tunnel was then tested, using the same testing method as in Example 1. The specific test results for the reverberation time after modification are shown in Table 7, and the specific test results for the longitudinal attenuation rate per unit distance are shown in Table 8. The noise attenuation performance of Tunnel No. 1 after modification is calculated, as shown in Table 9.

[0076] Table 7. Reverberation time of Tunnel No. 1 after renovation (unit: seconds)

[0077]

[0078] Table 8. Longitudinal attenuation rate of Tunnel No. 1 after renovation (unit: dB / m)

[0079]

[0080] Table 9 Noise Attenuation Performance of Tunnel No. 1 After Renovation (Table 9)

[0081]

[0082] Example 4

[0083] This invention uses Tunnel No. 2 in Example 2 as an example to illustrate the method for low-noise road surface modification in highway tunnels according to this invention. The test results in Example 2 show that the noise attenuation performance of the tunnel is good. To achieve a better noise reduction effect, the modified road surface should be paved with at least one layer of large-void asphalt. In this example, the 4cm SMA-13 ​​upper layer and 6cm AC-20 lower layer of the tunnel are replaced with a 4cm PAC-13 large-void asphalt upper layer and a 6cm AC-20 lower layer, respectively. The porosity of the 4cm PAC-13 large-void asphalt upper layer is 20%. The noise attenuation performance of the modified road surface in the highway tunnel is tested, and the test method is exactly the same as that of Tunnel No. 1. The specific test results of the reverberation time after modification are shown in Table 10, and the specific test results of the longitudinal attenuation rate are shown in Table 11. The noise attenuation performance of Tunnel No. 2 after modification is calculated as shown in Table 12.

[0084] Table 10. Reverberation time of a certain No. 2 tunnel after renovation (unit: s)

[0085]

[0086] Table 11. Longitudinal attenuation rate of a certain No. 2 tunnel after renovation (unit: dB / m)

[0087]

[0088] Table 12 Noise Attenuation Performance of Tunnel No. 2 After Renovation Table 12 Noise Attenuation Performance of a Certain Tunnel No. 2

[0089]

[0090] In the above embodiments, considering the height restrictions inside the tunnel, when modifying the road surface, the two layers of road surface structure are removed and two new layers of road surface structure are laid, and the height of each layer of road surface structure remains unchanged; however, as an achievable implementation method, other methods can also be used for modification, such as not removing the original road surface structure and laying it directly on the road surface.

[0091] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the claims.

Claims

1. A method for testing the road surface noise attenuation performance in highway tunnels, characterized in that, Includes the following steps: (1) Arrange the noise testing system according to the set points and test the cross section reverberation time and longitudinal section attenuation rate of the road surface respectively; the noise testing system includes a sound source and a sound pressure acquisition unit, wherein the sound source is arranged above the center line of the road, and multiple cross section sound pressure acquisition units are arranged on the cross section of the sound source, and multiple sets of longitudinal section sound pressure acquisition units are arranged sequentially on the longitudinal section of the sound source along one side of the sound source; in the horizontal direction, the spacing between each two adjacent sets of longitudinal section sound pressure acquisition units is equal; The method for testing the cross-sectional reverberation time is as follows: turn on the sound source to output a stable sound pressure level, the sound source emits pink noise continuously at a frequency of 63-10kHz; turn off the sound source, use the arranged cross-sectional sound pressure acquisition units to collect the noise attenuation signal measured after the sound source is interrupted, plot the noise attenuation curve, and calculate the average reverberation time of multiple cross-sectional sound pressure acquisition units. The test method for the longitudinal attenuation rate of the longitudinal section includes: turning on the sound source to output a stable sound pressure level, with the sound source emitting a frequency of 63-10kHz, and continuously emitting pink noise; using the arranged longitudinal section sound pressure acquisition units to acquire the noise attenuation signal measured under a steady-state sound field, calculating the longitudinal attenuation rate per unit distance between each pair of adjacent longitudinal section sound pressure acquisition units and calculating the average value, thereby obtaining the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units. (2) Calculate the road noise attenuation index (NAI) according to the following formula: NAI=100 / (1+0.11 ); Among them, T 60 R is the average reverberation time value of multiple cross-sectional sound pressure acquisition units obtained in step (1), in seconds; R is the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units, in dB / m. (3) The noise reduction performance of the road surface is evaluated based on the road surface noise reduction index (NAI).

2. The method for testing the road surface noise attenuation performance in highway tunnels according to claim 1, characterized in that, In step (3), the noise reduction performance of the road surface is evaluated. When 90 < NAI ≤ 100, the evaluation result is excellent; when 80 < NAI ≤ 90, the evaluation result is good; when 70 < NAI ≤ 80, the evaluation result is average; when 60 < NAI ≤ 70, the evaluation result is second best; when 0 < NAI ≤ 60, the evaluation result is poor.

3. The method for testing the road surface noise attenuation performance in highway tunnels according to claim 1 or 2, characterized in that, When testing the cross-sectional reverberation time and longitudinal attenuation rate, the sound pressure level output by the sound source remained stable at 100 dB.

4. The method for testing the road surface noise attenuation performance in highway tunnels according to claim 3, characterized in that, Reverberation time T of each cross-sectional sound pressure acquisition unit 60i The calculation method is as follows: T 60i = ； in, , These are the sound pressure level attenuation values ​​measured sequentially after the sound source was turned off. =25dB, =5dB, and They are respectively and The test time corresponding to the sound pressure level, i=1, 2...n, where n is the total number of cross-sectional sound pressure acquisition units.

5. The method for testing the road surface noise attenuation performance in highway tunnels according to claim 4, characterized in that, The sound source is positioned above the centerline of the road surface inside the highway tunnel, at a height of 0.6m above the road surface. The cross-sectional sound pressure acquisition unit is positioned on the cross-section of the sound source, with two points each above the centerline, above the centerline of the half of the road surface located on one side of the centerline, and above the edge line of the half of the road surface. The heights of the two points are 1.2m and 2.6m, respectively.

6. The method for testing the road surface noise attenuation performance in highway tunnels according to claim 5, characterized in that, Multiple sets of longitudinal profile sound pressure acquisition units are set up on one side of the sound source. The horizontal distance between any two adjacent sets of longitudinal profile sound pressure acquisition units is 30 meters. The horizontal distance between the longitudinal profile sound pressure acquisition unit closest to the sound source and the sound source is also 30 meters. The distance between the longitudinal profile sound pressure acquisition unit closest to the tunnel entrance and the tunnel entrance is greater than or equal to 30 meters. Each set of longitudinal profile sound pressure acquisition units has two points set up above the centerline of the road, with the heights of the two points being 1.2 meters and 2.6 meters, respectively.

7. A method for low-noise road surface modification in highway tunnels, characterized in that, Includes the following steps: (1) Arrange the noise testing system according to the set points, and test the cross section reverberation time and longitudinal section attenuation rate of the road surface to be modified respectively; the noise testing system includes a sound source and a sound pressure acquisition unit, wherein the sound source is arranged above the center line of the road, and multiple cross section sound pressure acquisition units are arranged on the cross section of the sound source, and multiple sets of longitudinal section sound pressure acquisition units are arranged sequentially on the longitudinal section of the sound source along one side of the sound source; in the horizontal direction, the spacing between each two adjacent sets of longitudinal section sound pressure acquisition units is equal; The method for testing the cross-sectional reverberation time is as follows: turn on the sound source to output a stable sound pressure level, the sound source emits pink noise continuously at a frequency of 63-10kHz; turn off the sound source, use the arranged cross-sectional sound pressure acquisition units to collect the noise attenuation signal measured after the sound source is interrupted, plot the noise attenuation curve, and calculate the average reverberation time of multiple cross-sectional sound pressure acquisition units. The test method for the longitudinal attenuation rate of the longitudinal section includes: turning on the sound source to output a stable sound pressure level, with the sound source emitting a frequency of 63-10kHz, and continuously emitting pink noise; using the arranged longitudinal section sound pressure acquisition units to acquire the noise attenuation signal measured under the steady-state sound field, calculating the longitudinal attenuation rate per unit distance between each pair of adjacent longitudinal section sound pressure acquisition units and calculating the average value, to obtain the average value R of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units. (2) Calculate the road noise attenuation index (NAI) according to the following formula: NAI=100 / (1+0.11 ); Among them, T 60 R is the average reverberation time value of the multiple cross-sectional sound pressure acquisition units obtained in step (1), in seconds; R is the average value of the longitudinal attenuation rate per unit distance of multiple sets of longitudinal section sound pressure acquisition units, in dB / m. (3) The road surface is modified to be low-noise based on the road noise attenuation index (NAI). When 80 < NAI ≤ 90, the modified road surface is paved with at least one layer of large void asphalt; when 70 < NAI ≤ 80, the modified road surface is paved with at least two layers of large void asphalt; when NAI ≤ 70, the modified road surface is paved with at least two layers of large void asphalt, of which at least one layer is a high-damping large void asphalt layer.

8. The method for low-noise road surface modification in highway tunnels according to claim 7, characterized in that, The large-void asphalt layer is a low-noise pavement layer with a porosity greater than or equal to 18%, and the high-damping large-void asphalt layer is a low-noise pavement layer with a porosity greater than or equal to 18% and a damping ratio greater than or equal to 40%.

9. The method for low-noise road surface modification in highway tunnels according to claim 8, characterized in that, When the large-void asphalt layer is used as the surface layer, its nominal maximum aggregate size is any one of 4.75mm, 9.5mm, 13.2mm, and 16mm, and its thickness is 1cm to 5cm; when the large-void asphalt layer is used as the lower layer, its nominal maximum aggregate size is any one of 13.2mm, 16mm, 19mm, and 26.5mm, and its thickness is 2.5cm to 8cm.

10. The method for low-noise road surface modification in highway tunnels according to any one of claims 7-9, characterized in that, The mixture of the large-void asphalt layer contains an elastic component, which is at least one of rubber powder, rubber particles, and polyurethane; or, the porosity of the large-void asphalt layer is greater than or equal to 25%.

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