Noise Reduction Performance Of Highway Sonic Crystal Noise Barrier With Resonance-sound Absorption Mechanism

The rapid development of highways has brought convenient transportation and economic growth,and at the same time,the deterioration of the acoustic environment along the route cannot be ignored.Although noise barriers are considered to be the most effective measure,they also have many shortcomings.For example,they are affected by the law of mass,low and medium frequency noise reduction effects are limited and lack pertinence,are greatly affected by wind loads,and have poor integration with the landscape along the road.Therefore,highway noise barriers are in urgent need of innovation with new materials and new structures.As a periodic artificial material with band gap characteristics,sonic crystals can effectively control sound waves in a specific range by constructing the band gap.This paper designs a highway sonic crystal noise barrier based on the principle of resonancesound absorption.Combining the principles of Bragg scattering with resonance and sound absorption effectively expands the band gap control range and noise reduction effect.First,the in-situ measurement of the highway noise spectrum was conducted to determine the target frequency band,then the band structure design and noise reduction performance simulation based on the finite element method was carried out,and the indoor semianechoic experiment and in-situ experiment respectively based on the 2D and 3D simulation results was conducted.In-site measurements were performed,and the simulation results were also verified.Finally,the relevant benefit analysis of the sonic crystal noise barrier was carried out.The main conclusions are as follows:(1)The main noise frequency bands of highways are 315-500 Hz and 800-1250 Hz,of which 400 Hz and 1000 Hz have peaked.High-speed noise is mainly composed of vehicle-tire noise and the engine noise of large and medium-sized vehicles;(2)The range of the band gap can be effectively controlled by changing the geometric size of the scatterer.Commonly used steel,cement concrete,PVC,or aluminum will not have a significant impact on the band gap;(3)The 2D infinite period finite element model can characterize the best noise reduction performance of the sonic crystal noise barrier;the 2D finite period finite element model can effectively predict the indoor experiment,and the sonic crystal noise barrier with resonance unit can perform effective peak clipping,the maximum insertion loss is 22.1d B,the noise reduction range is in good agreement with the band gap,and the2 D finite period calculation results are in good agreement with the indoor experimental results,with an error of 1.5-2d B;(4)In the 3D infinite-period finite element model,the possible impact of the diffraction from the top of the noise barrier and ground reflection is effectively considered,and the actual use effect of high-speed field can be effectively predicted,and the error is below 3d B;under field conditions,the noise reduction effect of the sonic crystal noise barrier is better than that of the cement concrete noise barrier by 0.2-2.1d B,and the insertion loss decreases more slowly with the increase of the distance behind the barrier;(5)Gradient placement of scatterers,filling of porous sound-absorbing media,and the use of micro-perforated walls can all play an influential reinforcement role,especially outside the band gap.The combination of multiple noise reduction mechanisms is beneficial to enhance applicability of sonic crystal noise barrier;The sonic crystal noise barrier realizes the organic combination of the new noise reduction concept and the noise barrier,conforms to the sustainable principle of today’s green transportation,has the characteristics of good noise reduction performance,strong pertinence,and pleasing aesthetics.It has a good application and promotion prospect in the prevention and control of highway noise.