An analytical solution method capable of determining the geometric configuration and developed tensile forces of mooring lines associated with fixed plate/pile or drag anchors has been developed. The solution method, satisfying complete equilibrium conditions, is capable of analyzing multi-segmented mooring lines that can consist of either chains, cables, or wires embedded in layered seafloor soils. The solution method utilizes a systematic iterative search method based on specific boundary conditions. This paper describes the principles associated with the development of the solution for the mooring line analysis. Comparisons of predictions with results from a series of field tests of mooring lines on various types of drag anchors are also described. Comparisons include the tension in anchor, the length of mooring line on the bottom, and the angle of mooring line at the water surface buoy. Results indicate that the analytical solution method is capable of predicting the behavior of mooring lines with high degree of accuracy.
The US Navy developed an analytical solution method that can analyze offshore and deep water mooring lines associated with embedded drag and fixed anchors (Bang, 1996). Mooring lines may be comprised of multi-segments with different material and/or geometric properties and embedded in a general seafioor soil having either cohesion or friction or both. Any number of sinkers can also be added to the suspended portion of the mooring line within the water. Solutions can be obtained with a fixed total length of the mooring line, a fixed horizontal length of the mooring line, or a fixed exit angle of the mooring line at the seafloor surface. The validity of the developed method of analyzing mooring lines embedded in cohesive seafloor soils has been verified through comparisons with laboratory centrifuge model tests (Bang, et. al, 1996; Bang, et. al, 1999).
