2020 Volume 76 Issue 2 Pages I_516-I_521
In this study, underwater acoustic experiments are conducted with water tank to obtain basic knowledge that contributes to the technology for reducing pile-driving noise by hydraulic hammer. In this experiment, prior to testing the applicability in the actual sea area, simulated pile-driving is carried out in two types of test tanks (volume: 1.0 m3, 450 m3). In a small tank, φ46.8 mm steel pipe is hit with various noise reduction measures in combination, and the noise reduction effect in the water is evaluated. In a large tank, the effects of countermeasures determined from the results of small tank test are measured using φ250 mm steel pipe. As a result, it is confirmed that the sound pressure level is significantly reduced by the bubble curtain, bubble sleeve, and the combination of submerged mound and bubble curtain. In addition, the frequency band to be reduced tended to be different depending on the countermeasures.
