Pile Driving Predictions for Pile Driving from Floating Installation Vessels

Abstract

Abstract A common approach for offshore windfarms is the installation of the turbine on top of a steel monopile that is driven into the seabed with a vibratory hammer. The use of that hammer type has distinct advantages over that of an impact hammer. First, the installation time is shorter, and secondly, during the installation the vibratory hammer and the pile are both hanging from the winch of the onboard crane, which provides the option to redo the installation. And with the availability of reliable simulation software for pile driving with a vibratory hammer, with which the appropriate hammer size can be determined and optimized, the installation process is now a routine activity. But as windfarms are installed in increasingly deeper water, the size of the monopiles and thus their weights are increasing. As a result, one of the advantages of vibratory driving, i.e. that the pile is hanging from the winch, is also creating a problem, especially when the installation is done from a floating installation vessel. In that case it is essential that a site specific or even a pile specific installation protocol is developed, with which the target penetration depth can be achieved. This paper will describe the process of developing such an installation protocol and illustrate the process through a generic example.