多孔沥青混合料降噪的细观模拟与宏观试验

Meso simulation and macro experimental study of noise reduction in porous asphalt mixtures

沥青路面内部连通孔隙多,这些孔隙可实现声能向内能的转化,进而达到降噪效果。为了研究沥青路面孔隙内部的吸声原理,使其充分发挥降噪功能,采用有限元法建立了沥青路面孔隙结构的细观模型。利用声学的原理,开展透水沥青混合料OGFC-13的降噪模拟,并以AC-13和SMA-13作为对比研究,通过室内试验的实测结果进行模型仿真的合理性和准确性验证。以不同频率下沥青混合料的吸声效果和噪声衰减TL曲线的变化规律作为评价指标,论述了多孔沥青路面的吸声原理,分析了级配等对沥青路面降噪效果的影响程度。结果表明:透水沥青混合料OGFC-13的降噪性能优良,其内部大量连通孔隙组成的共振吸声结构可以有效降低路面噪声,而AC-13、SMA-13等密实型路面材料的孔隙率小,未充分具备吸声结构,因此其吸声效果相对较差。同时,研究得到了3种级配沥青混合料在不同频率下的噪声衰减TL曲线变化规律和吸声系数曲线变化规律,均为整体上先逐渐增加,达到最佳吸声频率范围后,再逐渐减小的趋势。此外,OGFC-13、SMA-13以及AC-13的最佳吸声频率分别在600,800和1000 Hz左右。研究结果对深入沥青路面,尤其是多孔沥青路面降噪原理及其变化规律的探讨具有重要的科学意义。

Currently,road traffic noise,especially urban road traffic noise,has become a more serious environmental pollution problem.Researchers have carried out a large number of noise reduction treatments and controls from noise sources,propagation paths and sound-receiving points.These methods have reduced the noise generated by vehicle driving to a certain extent,but there are also disadvantages such as long road network planning period and expensive sound barriers.Therefore,considering the influence factors of asphalt pavement material to make it reduce the noise generated by vehicle driving is the most effective method.The porous asphalt pavement has a lot of internal pores,and these pores,especially the connected pores,can realize the conversion of sound energy to mechanical energy and internal energy,and then achieve the effect of noise reduction.In order to give full play to this function of asphalt pavement noise reduction,it is necessary to understand its internal sound absorption mechanism in depth.The finite element method(FEM)was used to establish the mesoscopic model of the pore structure of asphalt mixture.Based on the principle of acoustics,the noise reduction characteristics of asphalt pavement were simulated.The influence of gradation and pore characteristics on the noise reduction performance of asphalt pavement was analyzed.AC-13 and SMA-13 were used for comparative study.At the same time,the results of indoor standing wave tube tests were used to verify the rationality and accuracy of the simulation.The results show that the permeable asphalt mixture OGFC-13 is a kind of pavement material with excellent noise reduction characteristics,and its resonant sound absorption structure composed of a large number of connected pores can effectively absorb the pavement noise.However,the void volumes of AC-13 and SMA-13 and other compacted pavement are so small,and do not fully have these sound absorption structures.As a result,the sound absorption effect is relatively poor.The transmission loss(TL)curve of noise attenuation and the curve of sound absorption coefficient of three graded asphalt mixtures were obtained at diffe-rent frequencies.On the whole,the absorption frequency increases gradually and then decreases gradually after reaching the best absorption frequency range.In addition,the best sound absorption frequency of OGFC-13 is around 600 Hz,SMA-13 is around 800 Hz and AC-13 is around 1000 Hz.The results of this study are of great scientific significance for the in-depth discussion of the principle of sound absorption and noise reduction of asphalt pavement,especially porous asphalt pavement,and its change law.