Recording and Analyzing Underwater Noise During Pile Driving for Bridge Construction

Underwater sound generated by pile driving was recorded during the Hong Kong-Zhuhai-Macau Bridge (China) construction in 2014.The important parameters on the source level, the transmission loss, the time-frequency characteristics, and the method of the noise measurement were introduced in this paper. Signal analysis showed that the waveform of pile driving resembles a series of short pulses, composed of many different frequencies with main frequency energy distribution from 100 Hz to 2 kHz; the maximum value occurs at about 200 Hz. The best-fit shallow water sound propagation model gave a root-mean-square source level of 208.2 dB re at 1 m, a transmission spreading coefficient of 17.76, and an absorption coefficient of 0.015 dB/m. The value of transmission loss is in good agreement with the results calculated by the Marsh and Schulkin (M&S) semi-empirical expressions above 1 kHz, but is higher than the M&S results under 1 kHz, which may be due to the muddy seabed and turbid sea water in our study area. Although it is difficult to compare our research results with other studies as there is a lack of details on monitoring conditions (including pile size, hammer energy, environmental background, etc.), this paper provides a new method for underwater noise monitoring and analysis for pile driving in shallow water.