Numerical modeling of a reduced scale mooring line experimental investigation for load attenuation evaluation

Resumo

Oil platforms are migrating into deep waters, where the maintenance of its position represents an
engineering challenge. It has become usual to adopt mooring systems composed of chains that extend from the
floating unit to the foundation element and, along its length, have an embedded segment in the seabed, shaped as
an inverse catenary, capable of attenuating the acting forces. Several studies have been conducted to improve the
understanding of soil-chain interaction and estimate the expected attenuation level according to each problem’s
characteristics. Investigations in this area can be developed under experimental approach, normally on reduced
scale, or under numerical approach, which allows the simulation of a wide range of scenarios. Therewith, the
present work aims to simulate experimental tests in 1:40 geometric scale that reproduce the segment of a mooring
line embedded in soil, using a numerical finite element model built in a commercial software (ANSYS). The model
considers soil elements as a perfect elastoplastic material, chain elements as an elastic material with tension only
behavior and pair of target and contact elements which simulates the interface between soil and chain. The obtained
results are discussed by means of stress distribution in soil and percentages of load attenuation.