CN101515302A - Acoustic design method for road noise barrier - Google Patents

Abstract

A method for acoustic design of road sound barriers, the steps are: 1) importing vector graphics in Cad format or raster images in jpg, bmp, tif and other formats used to characterize the terrain where the sound barrier is located; 2) calibrating the imported graphics, 3) On the basis of imported graphics, combined with the actual situation, draw entities such as roads, terrain, houses, woods, grassland, etc. If it is a CAD graphic, you can use the batch conversion function to complete the acoustic modeling Basic work; 4) Set noise prediction points at the protected sensitive points, calculate the noise value without barriers, and determine the barrier noise reduction index; 5) Simulate the sound barrier, adjust the height and length of the barrier, and preliminarily calculate the barrier geometry that meets the requirements Size; 6) Combined with the geometric dimensions of the sound barrier, simulate barriers with different structures and sound absorption coefficients, and calculate the noise reduction effect of the barrier again until the combination of geometric dimensions, structures and sound absorption coefficients that meets the requirements is calculated.

Description

Acoustic Design Method for Road Noise Barriers

technical field

The invention relates to road traffic noise control technology, in particular to an acoustic design method for road sound barriers, which belongs to the field of environmental protection engineering.

Background technique

The formation of dense and networked roads in modern cities not only brings convenience to transportation and economic prosperity to modern humans, but also brings us harm from noise pollution. Therefore, with the increasing awareness of human environmental protection, the requirements for reducing urban road noise pollution are getting higher and higher, and the sound barriers that can reduce urban road noise have gradually attracted the attention of related technology industries.

At present, there are many design methods for sound barriers, especially with the popularization and use of computer technology, the design methods in this technical field are increasingly dependent on computers. Internationally well-known ones include: Soundpan from Braunstein+Berndt in Germany, Lima from B&K in Denmark, and Stamin & Opinion in the United States. Because these software programs are composed of special operation interfaces and computer systems composed of very complex modules, there are quite high requirements for the professional background and professional level of the operators.

The "sound barrier design method" with the application number 200410041442.7 is disclosed in the Chinese patent literature. This method is to use a computer to complete the theoretical calculation of the height and length of the sound barrier, as well as the selection of structural form and material, sound field simulation, Sound barrier effect prediction, wind load strength check and other processes. At the same time, the software of this method adopts a guiding interface to gradually guide the operator to input the necessary parameters to complete the design work of each part.

Since this method involves most of the process of sound barrier design, the process of acoustic design method is less expounded. In the existing sound barrier design method, the main problems are:

1) The use of acoustic modeling under complex conditions is not accurate enough, and vector graphics such as Cad cannot be input to complete the basic work of acoustic modeling. The acoustic model mainly deals with simple terrain, but it is difficult to handle under complex conditions.

2) Due to the inaccuracy of acoustic modeling, the calculation results of the noise reduction effect of the sound barrier are not accurate enough. The existing methods refer to the theoretical calculation formula of the noise reduction effect of the sound barrier, which cannot accurately simulate the actual noise radiation situation.

3) In the noise reduction effect and calculation of the sound barrier, the specific influence of factors such as the structure and material of the sound barrier is less considered.

Due to the above-mentioned problems, the acoustic design method of the sound barrier is not perfect, nor can it carry out targeted acoustic design for complex conditions, which leads to the fact that the noise reduction effect of the sound barrier in actual use cannot reach the ideal state.

Contents of the invention

The purpose of the present invention is to propose a new sound barrier design method to solve the inaccurate problems existing in the current sound barrier design and improve the actual use effect of the sound barrier.

This acoustic design method for road acoustic barriers uses computer processing to obtain relevant data on the external dimensions, structural forms, wind load strength and material selection of the acoustic barrier, and saves and outputs the data. The specific design method is as follows:

(1) Import the vector graphics processed in Cad format, or the raster graphics in jpg, bmp or tif format, where the designed sound barrier is located.

(2) Select the graphics to be imported, choose the vector graphics in Cad format, and determine whether the unit ratio of the Cad graphics is consistent with the actual situation before importing. If it is consistent, use the default setting, and if it is inconsistent, use custom settings to modify the ratio, which can be modified through the import setting menu The properties of each layer of Cad distinguish the objects of different layers; if raster graphics are used for import, the graphics scale adjustment work should be completed through the calibration function after import.

(3) If the imported grid graphics are used, it is necessary to draw entities such as terrain, roads, houses, forests, grasslands, etc. in combination with the actual situation to complete the basic work of acoustic modeling.

(4) Set noise prediction points at the protected sensitive points, collect and calculate the noise value without barrier, and determine the noise reduction index of the sound barrier.

(5) Simulate the sound barrier at the location where the sound barrier is to be implemented, adjust the height or length of the sound barrier, and preliminarily calculate the geometric size of the sound barrier that meets the noise reduction index of the predicted point.

(6) According to the geometric size of the sound barrier, simulate the sound absorption coefficient of the barrier under different structural screen types and different sound-absorbing materials of the vertical type and the straight arc type, and calculate the noise reduction effect of the barrier again until the geometric size of the sound barrier that meets the requirements is calculated , the combination of structure and sound absorption coefficient.

In the CAD vector graphics, you can use the batch conversion function to complete the basic work of acoustic modeling.

When calculating the noise without barrier, the calculation method adopted is:

(1) Take the road sound source as two line sound sources with the midlines of the two lanes on both sides of the farthest side, and further differentiate the line sound source into smaller micro-regions according to the distance between the predicted point and the sound source segment, each differential segment is used as a point sound source to participate in the calculation.

(2) Calculate the noise contribution value of the point sound source in each micro-section to the predicted point, and consider the geometric divergence of sound, atmospheric absorption, ground effect and barrier attenuation caused by obstacles in the calculation according to the setting conditions.

(3) The noise contribution value of all point sound sources to the prediction point is superimposed to be the noise value of the prediction point.

Using the above method can solve the inaccurate problem in the above acoustic design, and at the same time, can calculate the noise reduction effect of the sound barrier composed of different structures and materials.

Description of drawings

Figure 1 is a flowchart of the acoustic design of the sound barrier;

Figure 2 is a schematic diagram of the acoustic calculation.

Figure 3-1~3-4 are schematic diagrams of the interface of the acoustic design model of the sound barrier;

Detailed ways

The specific implementation method of the present invention is given below, and the present invention is further described.

Utilize the acoustic design method of the sound barrier introduced in this technical scheme, and use Visual C++ to write the software. The specific implementation method is explained as follows:

1) Import the topographic map where the designed sound barrier is located, one is vector graphics in Cad format, and the other is raster graphics in jpg, bmp, tif and other formats. By importing these two graphics, it can basically deal with the actual situation. All topographic basemaps for .

2) After the graphic is imported, the next step is to calibrate the graphic. The so-called calibration is to adjust the graphic scale to be consistent with the actual scale. For raster graphics, you can use the calibration function to complete the calibration by inputting calibration points. For Cad vector graphics, you should Before importing, determine in Cad whether a unit of length is the actual 1m, if so, no calibration is required, and if not, the conversion function is used to complete the calibration.

3) After graphics calibration, the next step is the acoustic modeling work, mainly to complete the simulation work of roads, houses, woods, grasslands, terrains, etc. If it is a raster graphic, the simulation work needs to draw the above entity on the raster graphic. If it is a CAD vector map, the batch conversion function can be used to complete the drawing of the above entity. For example, the road layer of cad is the road layer, and the contour layer is the contour line layer, you can select the converted layer as the conversion condition through batch conversion, and convert the road layer and contourline layer into roads and contour lines recognized by the software to complete the acoustic modeling work.

4) Input the measured road source strength, road width, road height and other parameters respectively, and input sound absorption factors such as woods, grassland, and ground. Set noise prediction points at the protected sensitive points, calculate the noise value without barriers, and fine-tune the road source intensity and sound absorption factors such as woods, grassland or ground through the measured noise value to basically confirm that the two are basically consistent.

5) Simulate the sound barrier at the position where the sound barrier is to be implemented, adjust the height or length of the sound barrier, and preliminarily calculate the geometric size of the sound barrier that satisfies the predicted point and meets the noise reduction index of the barrier. The determination of the preliminary size is based on this size. Appropriate barrier structure and form.

6) According to the geometric size of the sound barrier, simulate the sound absorption coefficient of the barrier under different structural screen types and different sound-absorbing materials of upright type and straight arc type, and calculate the noise reduction effect of the barrier again until the geometric size and structure of the sound barrier that meet the requirements are calculated. And the combination of sound absorption coefficient.

When calculating the noise prediction value when there is no barrier, the calculation method adopted (see Figure 2) is:

(1) Take the centerlines of the two outermost lanes of the road as the two line sound sources.

(2) According to the set conditions, the line sound source is further divided into smaller differential segments, and each differential segment participates in the calculation as a point sound source.

(3) Under default conditions, the length of each micro-segment is not greater than the product of the length from the midpoint of the micro-segment to the predicted point and a certain constant K. The default K=0.5. Of course, this K can also be set to 0.2 or 0.1 times, the smaller the K value, the more micro-segments, the more accurate the calculation, but the calculation time is also longer.

(4) Use each micro-section as a point sound source, and calculate the noise contribution value of each point sound source to the predicted point, and consider the geometric divergence of sound, atmospheric absorption, ground effect, object reflection and obstacle caused by the calculation according to the setting conditions Barrier attenuation and other factors, the calculation formula is carried out in accordance with the relevant formula in GB/T 17247.2-1998 (Attenuation of Outdoor Sound Transmission in Acoustics Part 2: General Calculation Method).

(5) The noise contribution value of all point sound sources to the prediction point is superimposed to be the noise value of the prediction point.

The acoustic design method provided by this patent is applied to the sound barrier design of the first phase of the Shanghai Outer Ring Road. By comparing the actual noise reduction effect of 11 sound barrier monitoring along the line with the theoretical noise reduction effect calculated by this patent method, it shows that the two The difference is very small, the error is within 1dB.

In general, although the Shanghai Outer Ring Road has the characteristics of wide road width, fast vehicle speed, large flow rate, high proportion of large vehicles, and serious noise pollution along the line, the acoustic design method provided by this patent is applied to the sound barrier design example of the Outer Ring Road. The expected noise reduction effect has been achieved, and the acoustic environment of sensitive points along the line has also been greatly improved. From the aspects of increasing land use, real estate appreciation, improving people's livelihood, and creating a harmonious society, the sound barrier of the outer ring line designed by this acoustic design method is of great significance. It also shows that this method can be applied to the acoustic design of any road's sound barrier.

Claims (3)

1. A method for acoustic design of road audio barriers, using computer processing to obtain the external dimensions, structural forms, and wind load strength and material selection related data of the audio barriers, and saving and outputting the data. The specific design method is: (1) Import the vector graphics processed in Cad format, or the raster graphics in jpg, bmp or tif format, where the designed sound barrier is located; (2) Select the graphics to be imported, choose the vector graphics in Cad format, and determine whether the unit ratio of the Cad graphics is consistent with the actual situation before importing. If it is consistent, use the default setting, and if it is inconsistent, use custom settings to modify the ratio, which can be modified through the import setting menu The attributes of each layer of Cad are used to distinguish objects of different layers; if raster graphics are used to import, the graphics scale adjustment work should be completed through the calibration function after importing; (3) If the imported graphics are raster graphics, it is necessary to draw terrain, roads, houses, woods, grassland and other entities in combination with the actual situation to complete the basic work of acoustic modeling; (4) Set noise prediction points at protected sensitive points, collect and calculate the noise value without barriers, and determine the noise reduction index of the sound barrier; (5) Simulate the sound barrier at the location where the sound barrier is to be implemented, adjust the height or length of the sound barrier, and preliminarily calculate the geometric size of the sound barrier that meets the noise reduction index of the predicted point; (6) According to the geometric size of the sound barrier, simulate the sound absorption coefficient of the barrier under different structural screen types and different sound-absorbing materials of the vertical type and the straight arc type, and calculate the noise reduction effect of the barrier again until the geometric size of the sound barrier that meets the requirements is calculated , the combination of structure and sound absorption coefficient. 2. A method for acoustic design of road acoustic barriers according to claim 1, characterized in that: when using Cad vector graphics, the basic work of acoustic modeling is completed by using the batch conversion function. 3. A method for acoustic design of road acoustic barriers as claimed in claim 1, characterized in that: when calculating the noise value without barriers, the calculation method adopted is: (1) Take the road sound source as two line sound sources with the midlines of the two lanes on both sides of the farthest side, and further differentiate the line sound source into smaller micro-regions according to the distance between the predicted point and the sound source segment, each differential segment is used as a point sound source to participate in the calculation; (2) Calculate the noise contribution value of the point sound source in each micro-section to the predicted point, and consider the geometric divergence of sound, atmospheric absorption, ground effect and barrier attenuation caused by obstacles in the calculation according to the setting conditions; (3) The noise contribution value of all point sound sources to the prediction point is superimposed to be the noise value of the prediction point.

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