Method for determining the design value of the frequency of sound barriers for road maintenance

Abstract

The present invention provides a method for determining the frequency design value of a road maintenance sound barrier, comprising the following steps: (1) measuring and obtaining the 1 / 3 octave band sound pressure level of traffic noise at n sub-frequencies of a target design section, thereby obtaining one or more peak frequencies of the traffic noise; (2) setting two thresholds L th1 and L th2 , select the peak frequency that meets the conditions from the one or more peak frequencies obtained in step (1); (3) limit the design peak range of the single-layer porous pavement structure and the double-layer porous pavement structure. When the peak frequency cannot meet the requirements, the working frequency range of the sound barrier is correspondingly limited. The method of the present invention designs the peak frequency of highway noise design based on traffic noise, providing a reference for highway pavement structure design. At the same time, the pavement and sound frequency barrier designs are combined to optimize the comprehensive noise reduction effect of the two, further reducing the level of traffic noise pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of traffic noise control, and in particular relates to a method for determining a design peak value of a porous road surface sound absorption frequency according to traffic noise. Background Art

[0002] Using porous sound-absorbing pavement to reduce road noise is a method of controlling traffic noise. Porous sound-absorbing pavement has a higher porosity than ordinary pavement, and its porosity is usually between 15% and 25%. It forms various types of developed pores such as connected and semi-connected types inside, which can effectively consume sound energy and have good sound absorption performance. In the existing technology, a single or double layer of porous asphalt pavement is usually laid on the surface to improve the sound absorption and noise reduction effect of the pavement.

[0003] In order to maximize the sound absorption and noise reduction effect of the road surface, the sound absorption frequency peak of the porous road surface should be considered as a key indicator when designing the porous sound-absorbing road surface. Different road surfaces have different sound absorption frequency peaks. Generally speaking, a single-layer porous asphalt pavement has a sound absorption frequency peak in the medium and high frequency range, and a double-layer porous asphalt pavement has two sound absorption frequency peaks. However, the prior art has not disclosed a method for determining the design peak of the sound absorption frequency of a porous road surface, which makes it difficult for technicians in this field to confirm the design peak of the sound absorption frequency of the road surface.

[0004] In addition to porous sound-absorbing pavement, sound barriers are also the most common means of preventing and controlling road traffic noise. However, due to different design units, the two are currently designed and implemented independently. How to optimize the comprehensive noise reduction effect of the two measures when taking these two noise reduction measures at the same time and further reduce the level of traffic noise pollution is also a technical problem that needs to be urgently solved in this field. Summary of the invention

[0005] The present invention solves the technical problem of how to optimize the comprehensive noise reduction effect of porous sound-absorbing pavement and sound barrier noise reduction measures when both are adopted simultaneously to further reduce the level of traffic noise pollution, and further provides a method for determining the design peak value of the sound absorption frequency of the porous pavement according to traffic noise.

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

[0007] A method for determining a design value of a frequency of a sound barrier for maintaining a pavement, comprising the following steps:

[0008] (1) Measure the existing road noise at n sub-frequencies The 1 / 3 octave band sound pressure level under the condition of ; When the peak frequency When the number of is less than or equal to 2, the peak frequency The target peak frequency ; When the peak frequency When the number of is greater than 2, the peak frequency Screen and select 2 target peak frequencies ;

[0009] (2) When the target peak frequency is a value, record it as ; The maintenance road surface adopts a single-layer porous pavement structure, and the sound absorption peak frequency of the single-layer porous pavement structure is evaluated:

[0010] If the peak frequency of sound absorption The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency The sound barrier adopts a straight plate sound barrier; the lower limit value of the effective sound absorption frequency range refers to the lower limit frequency value corresponding to the time when the sound absorption coefficient of the sound absorption peak curve drops to half of the peak value, and the lower limit frequency value is less than the sound absorption peak frequency;

[0011] If the peak frequency of sound absorption The lower limit of the effective sound absorption frequency range is greater than The lower limit of the effective sound absorption frequency range is , then the sound barrier adopts a straight plate sound barrier and is equipped with a supplementary structure, and the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is The frequency range segment of the lower limit of the effective sound absorption frequency range;

[0012] When the target peak frequency is obtained as two values, they are recorded from low to high. and The maintenance road surface adopts a double-layer porous road surface structure, and the two target sound absorption peak frequencies of the double-layer porous road surface structure are recorded in order from low to high. and the second sound absorption peak frequency , and evaluate it:

[0013] If the first sound absorption peak frequency is met at the same time and the second sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency and The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency The upper limit value of the effective sound absorption frequency range is the upper limit frequency value corresponding to the time when the sound absorption coefficient of the sound absorption peak curve drops to half of the peak value, and the upper limit frequency value is greater than the sound absorption peak frequency;

[0014] If any of the above conditions is not met, the sound barrier shall be a straight plate sound barrier with a supplementary structure; the operating frequency range of the supplementary structure shall be determined in the following manner:

[0015] The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is greater than The lower limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is The frequency range segment of the lower limit of the effective sound absorption frequency range;

[0016] The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is less than the target peak frequency The upper limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range to the target peak frequency The frequency range segment of the upper limit value of the effective sound absorption frequency range;

[0017] The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency The upper limit of the effective sound absorption frequency range, and the second sound absorption peak frequency The lower limit of the effective sound absorption frequency range is greater than the target peak frequency The lower limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is from the second sound absorption peak frequency The frequency range segment with the lower limit of the effective sound absorption frequency range.

[0018] In step (1), the existing road noise is measured at n sub-frequency using the statistical method or the close-range method. The 1 / 3 octave band sound pressure level is measured.

[0019] Step (1) Neutron frequency The value range is ∈[125,1600].

[0020] In step (1), n ​​sub-frequencies Uniformly distributed in the range [125,1600].

[0021] In step (1), set the first threshold and the second threshold , for the peak frequency Screen and select 2 target peak frequencies that meet the following conditions:

[0022] I. 1 / 3 octave band sound pressure level of peak frequency and n sub-frequencies The difference between the maximum values ​​of the 1 / 3 octave band sound pressure levels under ,Right now:

[0023] ;

[0024] II. The difference between the 1 / 3 octave band sound pressure level of the peak frequency and the edge band value of traffic noise is less than or equal to the second threshold ,Right now:

[0025] ;

[0026] in, Calculated according to the following formula:

[0027] w =2

[0028] w It refers to the bandwidth of the i-th sound absorption peak curve;

[0029] After the above process, from the peak frequency 2 target peak frequencies were obtained by screening .

[0030] The supplementary structure is an active noise reduction device.

[0031] The method of determining the design value of the frequency of the sound barrier for maintaining the road surface according to traffic noise in the present invention can design the peak value of the design frequency of highway noise according to traffic noise, and provide a reference for the design of highway pavement structure. At the same time, the pavement design is combined with the sound barrier design. When these two noise reduction measures are taken at the same time, the comprehensive noise reduction effect of the two is optimized, and the level of traffic noise pollution is further reduced.

[0032] In the present invention, when the sound absorption peak frequency of the single-layer porous pavement meets the sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency The lower limit of the effective sound absorption frequency range, the two sound absorption peaks of the double-layer porous asphalt pavement and At the same time, the first sound absorption peak frequency is met and the second sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency and The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency If the upper limit of the effective sound absorption frequency range is reached, a straight-plate sound barrier should be set up.

[0033] The structure of the straight plate sound barrier is simple, and its design parameters such as size and position can be designed according to the existing technology HJ / T 90-2004 "Acoustic Design and Measurement Specifications for Sound Barriers". The straight plate sound barrier has a relatively uniform noise reduction degree for noise in each frequency band, which can achieve a good noise reduction effect. When the sound absorption peak frequency of a single-layer or multi-layer porous pavement does not meet the above conditions, the sound absorption effect can be compensated by further adding a supplementary structure to the straight plate sound barrier structure.

[0034] Among them, for double-layer porous asphalt pavement. The lower limit of the effective sound absorption frequency range is The frequency range of the lower limit of the effective sound absorption frequency range, the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range to the target peak frequency The frequency range of the upper limit of the effective sound absorption frequency range, The lower limit of the effective sound absorption frequency range is from the second sound absorption peak frequency The working frequency range of the supplementary structure is selected based on the priority of the frequency range segment of the lower limit value of the effective sound absorption frequency range. This compensation method of the present invention gives priority to compensating the low-frequency part. Since the low-frequency wavelength is longer, the low-frequency part of the sound barrier insertion loss is often smaller than the high-frequency part. Therefore, compared with the high-frequency compensation method, the low-frequency compensation method can obtain a better noise reduction effect. And considering the road surface factors comprehensively, under the condition of a certain thickness, the road surface's sound absorption ability for low-frequency noise is also weaker than that for high-frequency noise. Therefore, giving priority to compensating the low-frequency part can better make up for the lack of road surface sound absorption.

[0035] In order to make the technical solution of the method for determining the frequency design value of the road maintenance sound barrier described in the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. DETAILED DESCRIPTION

[0036] This embodiment provides a method for determining a design value of a frequency of a road maintenance sound barrier, comprising the following steps:

[0037] (1) Use the statistical method in GBT20243.1 or the close-range method in ISO11819-2 to measure the existing road noise and obtain the 1 / 3 octave frequency spectrum of the road traffic noise, that is, n sub-frequency The 1 / 3 octave band sound pressure level under the above conditions is recorded in order from low to high frequency as follows:

[0038]

[0039] Then, at least one peak frequency of road noise is obtained. ; When the peak frequency When the number of is less than or equal to 2, the peak frequency That is the target peak frequency ;

[0040] When the peak frequency When the number of is greater than 2, the peak frequency Screen and select 2 target peak frequencies ; The screening method is: set the first threshold and the second threshold , select 2 target peak frequencies that meet the following conditions:

[0041] I. 1 / 3 octave band sound pressure level of peak frequency and n sub-frequencies The difference between the maximum values ​​of the 1 / 3 octave band sound pressure levels under ,Right now:

[0042] II. The difference between the 1 / 3 octave band sound pressure level of the peak frequency and the edge band value of traffic noise is less than or equal to the second threshold ,Right now:

[0043] ;

[0044] in, is the main energy bandwidth of traffic noise, Calculated according to the following formula:

[0045] w =2 ;

[0046] In general, the two thresholds in step (2) are set as: ,

[0047] After the above process, from the peak frequency 2 target peak frequencies were obtained by screening .

[0048] As a preferred embodiment, the sub-frequency The value range is ∈[125,1600], and n sub-frequencies Uniformly distributed in the range [125,1600].

[0049] (2) When the target peak frequency is a value, record it as ; The maintenance road surface adopts a single-layer porous pavement structure, and the sound absorption peak frequency of the single-layer porous pavement structure is evaluated:

[0050] If the peak frequency of sound absorption The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency The sound barrier adopts a straight plate sound barrier; the lower limit value of the effective sound absorption frequency range refers to the lower limit frequency value corresponding to the time when the sound absorption coefficient of the sound absorption peak curve drops to half of the peak value, and the lower limit frequency value is less than the sound absorption peak frequency;

[0051] If the peak frequency of sound absorption The lower limit of the effective sound absorption frequency range is greater than The lower limit of the effective sound absorption frequency range is , then the sound barrier adopts a straight plate sound barrier and is equipped with a supplementary structure, and the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is The frequency range segment of the lower limit of the effective sound absorption frequency range;

[0052] When the target peak frequency is obtained as two values, they are recorded from low to high. and The maintenance road surface adopts a double-layer porous road surface structure, and the two target sound absorption peak frequencies of the double-layer porous road surface structure are recorded in order from low to high. and the second sound absorption peak frequency , and evaluate it:

[0053] If the first sound absorption peak frequency is met at the same time and the second sound absorption peak frequency The lower limits of the effective sound absorption frequency range are respectively less than or equal to the target peak frequency and The lower limit of the effective sound absorption frequency range, that is, the first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than the target peak frequency The lower limit of the effective sound absorption frequency range, the second sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than the target peak frequency The lower limit of the effective sound absorption frequency range.

[0054] And the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency The upper limit value of the effective sound absorption frequency range is the upper limit frequency value corresponding to the time when the sound absorption coefficient of the sound absorption peak curve drops to half of the peak value, and the upper limit frequency value is greater than the sound absorption peak frequency;

[0055] If any of the above conditions is not met, the sound barrier shall be a straight plate sound barrier with a supplementary structure; the operating frequency range of the supplementary structure shall be determined in the following manner:

[0056] The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is greater than The lower limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is The frequency range segment of the lower limit of the effective sound absorption frequency range;

[0057] The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is less than the target peak frequency The upper limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range to the target peak frequency The frequency range segment of the upper limit value of the effective sound absorption frequency range;

[0058] The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency The upper limit of the effective sound absorption frequency range, and the second sound absorption peak frequency The lower limit of the effective sound absorption frequency range is greater than the target peak frequency The lower limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is from the second sound absorption peak frequency The frequency range segment with the lower limit of the effective sound absorption frequency range.

[0059] In this embodiment, the supplementary structure is an active noise reduction device, which is installed on the top of the straight-plate sound barrier. The active noise reduction device adopts an active control method (ANC) and uses feedforward control to design the working target frequency range to be the corresponding frequency band range.

[0060] The straight-plate sound barrier refers to a sound barrier structure in which the sound barrier is in a plane shape. When the scale of the sound barrier is fixed, the sound barrier has the same effect on different frequencies of traffic noise. The design parameters such as the size, position, and material of the sound barrier can be designed according to HJ / T 90-2004 "Noise Barrier Acoustic Design and Measurement Specifications" in the prior art.

[0061] Example 1

[0062] In order to further demonstrate the technical effect of the method for determining the design value of the frequency of the sound barrier for maintaining a pavement described in the present invention, this laboratory explains the method and results of the present invention based on actual tests.

[0063] The method in this experimental example is the same as that described in the above embodiment, specifically, the close-range method is used to measure the existing road noise. Step (1) The measured A-weighted sound level measurement result of the roadside traffic noise of a certain road section has an obvious target peak, and the target peak frequency The effective sound absorption frequency range is the range from the lower limit frequency value to the upper limit frequency value corresponding to the sound absorption coefficient of the sound absorption curve dropping to half of the peak value, specifically [630,1250] Hz.

[0064] According to the characteristics of traffic noise, the maintenance road surface adopts a single-layer porous pavement structure, and the single-layer porous pavement structure is a 40mm thick PUC-10 porous pavement. The pavement sound absorption coefficient test results are as follows: The sound absorption peak frequency of the single-layer porous pavement structure is 1000Hz, and the effective sound absorption frequency range is [630,1250]Hz.

[0065] Right now The lower limit of the effective sound absorption frequency range is 630 Hz, which is equal to the target peak frequency. The lower limit of the effective sound absorption frequency range is consistent with the peak sound absorption frequency of a single-layer porous pavement in a specific implementation method. The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency The lower limit of the effective sound absorption frequency range is required. According to experimental tests, the road surface itself can improve the comprehensive noise reduction effect by about 2~3dB compared with the situation that does not meet the requirements. In this case, it is only necessary to arrange a straight plate sound barrier on the side of the single-layer porous road surface to achieve a good noise reduction effect.

[0066] Experimental Example 2

[0067] Take another road section as an example. The existing road noise is also measured. The A-weighted sound level measurement results of the roadside traffic noise on this road section have two target peak frequencies in the range of [125,1600] Hz. and ; The first sound absorption peak frequency is 250Hz, and the effective sound absorption frequency range is 125,400]Hz; second peak frequency The effective sound absorption frequency range is [630,1600] Hz.

[0068] According to the above traffic noise characteristics, the appropriate pavement structure design requirements are selected, and the pavement structure is 25mmPUC-10+40mmPAC-13. The sound absorption coefficient of the pavement is tested, and the first sound absorption peak frequency of the porous pavement is considered as 1 / 3 octave. is 500Hz, the effective sound absorption frequency range is [125,800]Hz, and the second sound absorption peak frequency is 1250Hz, and the effective frequency band is [800,1600]Hz.

[0069] At this time, in the effective frequency range of the first sound absorption peak of the porous maintenance pavement, the first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is 125Hz, which is consistent with the target peak frequency. The lower limit of the effective sound absorption frequency range is equal to that of the first sound absorption peak frequency. The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency The requirements for the lower limit of the effective sound absorption frequency range.

[0070] And the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is 800Hz, which is greater than the target peak frequency The upper limit of the effective sound absorption frequency range is 400Hz, which meets the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency The requirements for the upper limit of the effective sound absorption frequency range.

[0071] The second sound absorption peak of the porous maintenance pavement The lower limit of the effective sound absorption frequency range is 800Hz, which is greater than the target peak frequency. The lower limit of the effective sound absorption frequency range is 630Hz, which does not meet the second sound absorption peak The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency The lower limit of the effective sound absorption frequency range is required. Therefore, it is necessary to install an interference-type top structure on the straight-plate sound barrier, adopt an active control method (ANC), and use feedforward control to design the working target frequency range to [630,800] Hz. Compared with not setting up an active noise reduction device, or setting the frequency range of the active noise reduction device to a low frequency band below 630 Hz, this experimental example can improve the overall noise reduction effect by about 3.2~5.7dB by adopting a comprehensive noise reduction optimization method, and use active noise reduction control to reduce traffic noise in the medium and low frequency range.

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the claims.

Claims

1. A method for determining the design value of the frequency of a road maintenance sound barrier, characterized in that: The following steps are involved: (1) Measure the existing road noise at n sub-frequencies The 1 / 3 octave band sound pressure level under the condition of ; When the peak frequency When the number of is less than or equal to 2, the peak frequency The target peak frequency ; When the peak frequency When the number of is greater than 2, the peak frequency Screen and select 2 target peak frequencies ; (2) When the target peak frequency is a value, record it as ; The maintenance road surface adopts a single-layer porous pavement structure, and the sound absorption peak frequency of the single-layer porous pavement structure is evaluated: If the peak frequency of sound absorption The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency The sound barrier adopts a straight plate sound barrier; the lower limit value of the effective sound absorption frequency range refers to the lower limit frequency value corresponding to the time when the sound absorption coefficient of the sound absorption peak curve drops to half of the peak value, and the lower limit frequency value is less than the sound absorption peak frequency; If the peak frequency of sound absorption The lower limit of the effective sound absorption frequency range is greater than The lower limit of the effective sound absorption frequency range is , then the sound barrier adopts a straight plate sound barrier and is equipped with a supplementary structure, and the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is The frequency range segment of the lower limit of the effective sound absorption frequency range; When the target peak frequency is obtained as two values, they are recorded from low to high. and The maintenance road surface adopts a double-layer porous road surface structure, and the two target sound absorption peak frequencies of the double-layer porous road surface structure are recorded in order from low to high. and the second sound absorption peak frequency , and evaluate it: If the first sound absorption peak frequency is met at the same time and the second sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to the target peak frequency and The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency The upper limit value of the effective sound absorption frequency range is the upper limit frequency value corresponding to the time when the sound absorption coefficient of the sound absorption peak curve drops to half of the peak value, and the upper limit frequency value is greater than the sound absorption peak frequency; If any of the above conditions is not met, the sound barrier shall be a straight plate sound barrier with a supplementary structure; the operating frequency range of the supplementary structure shall be determined in the following manner: The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is greater than The lower limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is The frequency range segment of the lower limit of the effective sound absorption frequency range; The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is less than the target peak frequency The upper limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range to the target peak frequency The frequency range segment of the upper limit value of the effective sound absorption frequency range; The first sound absorption peak frequency The lower limit of the effective sound absorption frequency range is less than or equal to The lower limit of the effective sound absorption frequency range, and the first sound absorption peak frequency The upper limit of the effective sound absorption frequency range is greater than or equal to the target peak frequency The upper limit of the effective sound absorption frequency range, and the second sound absorption peak frequency The lower limit of the effective sound absorption frequency range is greater than the target peak frequency The lower limit of the effective sound absorption frequency range, then the working frequency range of the supplementary structure includes The lower limit of the effective sound absorption frequency range is from the second sound absorption peak frequency The frequency range segment with the lower limit of the effective sound absorption frequency range.

2. The method for determining the frequency design value of the road maintenance sound barrier according to claim 1, characterized in that: In step (1), the existing road noise is measured at n sub-frequency using the statistical method or the close-range method. The 1 / 3 octave band sound pressure level is measured.

3. The method for determining the frequency design value of the road maintenance sound barrier according to claim 1, characterized in that: Step (1) Neutron frequency The value range is ∈[125,1600].

4. The method for determining the frequency design value of the road maintenance sound barrier according to claim 2, characterized in that: In step (1), n ​​sub-frequencies Uniformly distributed in the range [125,1600].

5. The method for determining the frequency design value of the road maintenance sound barrier according to claim 2, characterized in that: In step (1), set the first threshold and the second threshold , for the peak frequency Screen and select 2 target peak frequencies that meet the following conditions: I. 1 / 3 octave band sound pressure level of peak frequency and n sub-frequencies The difference between the maximum values ​​of the 1 / 3 octave band sound pressure levels under ,Right now: ； II. The difference between the 1 / 3 octave band sound pressure level of the peak frequency and the edge band value of traffic noise is less than or equal to the second threshold ,Right now: ; in, is the energy bandwidth of the ith sound absorption peak, calculated according to the following formula: It refers to the bandwidth of the i-th sound absorption peak curve; After the above process, from the peak frequency 2 target peak frequencies were obtained by screening .

6. The method for determining the frequency design value of the road maintenance sound barrier according to claim 3, characterized in that: The supplementary structure is an active noise reduction device.

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