ABSTRACT
Large, floating structures are widely used by the oil and gas industry to facilitate the extraction of hydrocarbon resources in deep waters throughout the world. These structures are tethered to the seafloor using anchors and mooring lines, and steel catenary risers (SCRs) are regularly used to transport oil and gas between these structures and other facilities. SCRs are attached directly to the structures (Figure 1), and thus are affected by any movements of the structure due to wave motions. This results in cyclic loading behavior at the touchdown zone (TDZ), the region in which the riser contacts the seafloor. A major design concern regards the fatigue life of the riser in the TDZ, which is strongly influenced by the soil conditions in this region (Hatton 2006). Potential fatigue failures are related to bending stress in the SCR (e.g. Aubeny et al. 2006, Clukey et al. 2005, Randolph & Quiggin 2009), which depends primarily on the seafloor stiffness, variation in embedment depth of the SCR throughout the TDZ, and amplitude of movements of the SCR due to wave and current motions.
