Periodic Noise Characteristics and Acoustic Control in Long Highway Tunnels: An FEM Study with In Situ Validation

Area of Science:

• Acoustics
• Environmental Engineering
• Computational Mechanics

Background:

• Noise pollution in long highway tunnels and underground interchanges is a major environmental concern.
• This noise impacts drivers and nearby residents, necessitating effective mitigation strategies.

Purpose of the Study:

• To develop and validate an acoustic finite element model for characterizing tunnel noise.
• To evaluate and optimize noise mitigation measures within tunnel environments.

Main Methods:

• An acoustic finite element model was created using Leuven Measurement Systems (LMS) Virtual Lab.
• The model was validated against in situ monitoring data, achieving deviations within 3 dB(A) and confirmed by Kappa consistency tests.

Main Results:

• Sound pressure levels (SPLs) were highest near the tunnel center, with periodic fluctuations, and concentrated between 125 Hz and 500 Hz.
• Higher SPLs were recorded at 1.8 m compared to 1.2 m and 1.5 m, indicating increased exposure for drivers of larger vehicles.
• Sound-absorbing panels (expanded perlite, metal micro-perforated, FC-PP) and porous asphalt demonstrated superior noise reduction.

Conclusions:

• The validated acoustic model accurately represents tunnel noise fields.
• Optimized noise mitigation includes specific sound-absorbing lining materials and porous asphalt pavements.
• Effective noise control strategies are crucial for improving environmental quality in tunnel infrastructures.