摘要: |
Impact pile driving of steel piles in marine environments produces extremely high sound levels in the water. It has been shown that current pile driving noise attenuation techniques, such as bubble curtains and cofferdams, provide limited noise reduction because significant noise is transmitted through the sediment into the water. Similarly, the effectiveness of surrounding the pile in the water with a double walled steel tube was shown in an earlier WSDOT study to be limited. To address this problem, a double walled pile has been developed to decrease the total noise transmitted into the water. The double walled pile consists of two concentric tubes connected by a special driving shoe, with an air gap between the two tubes. The double walled pile is driven into the sediment by using traditional equipment to strike the inner tube only. The air gap between the inner and outer tube prevents the radial deformation wave produced by the pile hammer from interacting with the water and the sediment. This report discusses the design of the double wall pile and presents the results from finite element modeling of the pile, scaled prototype testing, and full-scale field testing in Commencement Bay, Puget Sound, Washington. The tests showed that the double walled piles reduce the peak sound pressure over 20 dB relative to single walled piles at a range of approximately 8 meters. They also showed that, in contrast, only a 3- to 6-dB reduction is obtained when a bubble curtain is used on a full-scale, single walled pile. |