Underwater noise created by impact pile driving can reach sound levels that have negative effects on aquatic wildlife. To address this problem, UW researchers developed a double-walled pile to decrease the noise transmitted into the water and substrate. The double-walled pile consists of two concentric steel pipe piles flexibly connected by a special driving shoe, which creates an air gap between the two tubes. The double-walled pile is driven into the sediment with traditional equipment that strikes only the inner pile. The air gap between the inner and outer pile and the flexible coupling prevent the radial deformation wave produced by the pile hammer from interacting with the water and the sediment and thus reduce noise levels.
After two successful full-scale tests of the double-walled pile technology, what remains to allow the use of this new technology in commercial projects is a way for structural engineers to estimate drivability, stresses in the piles, and load capacity during the design phase of the project (WEAP analysis). In addition, structural engineers must be able to determine the load capacity of the pile after driving so that they can know whether the installed pile can carry the intended loads (CAPWAP analysis). For this project, the researcher, in cooperation with Pile Dynamics Inc and Marine Construction Technology, PBC, will use data collected from the two field tests to modify existing commercial software for predicting drivability and stresses in the piles (WEAP analysis) and for estimating load capacity after driving (CAPWAP analysis). This will give engineers an industry standard tool for predicting and confirming the structural integrity of the installed piles.
Principal Investigator: Per G. Reinhall, Mechanical Engineering, UW
Sponsor: WSDOT
WSDOT Technical Monitor: Tom Bertucci
WSDOT Project Manager: Jon Peterson
Scheduled completion: June 2017