Cyclic Strength of Soils at Atlantic Shores Offshore Wind Farm

The cyclic soil behavior of North Sea clays and silica sands have been well-documented (Andersen 2004, 2009, etc), and have been used globally to develop soil models and design foundations for structures subjected to cyclic wave loading. The recent development of offshore wind farms within the Atlantic Offshore Continental Shelf (OCS) in the U.S. have prompted the large-scale design of fixed-bottom foundations of offshore wind structures, which are designed to be highly dynamic. In contrast to North Sea soils, very few data have been published regarding the strength behavior of typical Atlantic OCS soils. This has prompted the need to review industry-accepted soil models and cyclic design procedures based on empirical data and model testing from the North Sea and whether these may be applicable to Atlantic OCS soils. This paper presents cyclic soil data from a series of triaxial and direct simple shear tests on clay, silt, and sand samples from the Atlantic Shores Offshore Wind Lease Area in offshore New Jersey. A comparison of the soil behavior is made to published North Sea soils data and recommendations are provided on soil parameters for application to foundation design procedures for offshore wind structures within the Atlantic OCS.