Single segmented mooring lines were tested in a geotechnical centrifuge for the purpose of calibrating the analytical solution developed for the analysis and design of various mooring lines associated with underwater drag/permanent anchors. The model mooring lines included steel ball chains and wire cables placed at various depths within the soft clayey seafloor soil. The mooring lines were loaded to preset tensions at the water surface under an elevated acceleration inside the centrifuge to simulate the field stress conditions experienced by the prototype mooring lines. This paper describes the calibration of two factors that are used as part of the input parameters in the analytical solution of mooring lines and considers the effect of chasing wires that were used in the experiment to determine the locations of the mooring lines.
The U.S. Naval Facilities Engineering Service Center (NFESC) conducted a series of centrifuge model tests (Law, et. al, 1994) on buried mooring lines in order to validate the analytical model developed by Bang (1996). During the centrifuge model tests a set of chasing wires was attached to the mooring chains and cables. Figure - 1 shows a schematic sketch of the layout of the mooring line and chasing wires. The chasing wires were used to locate the exact geometries of the mooring chains/cable during transition from the initial to the final position due to the applied load. However, it was found later that the chasing wires had a rather significant effect on the mooring line geometry and tension, particularly on the mooring cable because of its thin cross section.
The primary objective of the centrifuge model tests was to obtain the detailed load transfer mechanism of the mooring line embedded in a cohesive seafloor. Therefore, the mooring lines were fixed at specific depths.