ACOUSTICAL DIAGNOSES OF POROUS DRAINAGE PAVEMENTS

摘要

Road traffic noise reduction of drainage pavement with small air gaps among grains is well known. However, traffic flow over many years fills those gaps with mud and sand, thereby degrading the noise reduction effect. To regain that effect, cleansing or reconstructing the pavement is necessary after precise assessment of the air gaps. For that purpose, acoustical diagnoses of drainage pavement are proposed and test results are introduced. One method is to check sound absorption of the pavement surface, which normally has high absorption near frequencies of 1 kHz, which is related to the reduction of road traffic noise. The use of a particle velocity sensor together with a microphone greatly simplifies measurements and judgments. Another analysis method is based on sound propagation through air gaps in the pavement. Transmission characteristics clearly indicate pavement conditions. Low-attenuation sound transmissions are shown in a wide frequency range below 1 kHz for sound air gaps, and weak transmissions in a narrow frequency range are shown when air gaps are filled. These acoustic diagnostic methods are effective in investigating porous drainage pavement.