Suction embedded plate anchors (SEPLAs) are used in deep and ultra-deep waters for temporary mooring of floating offshore structures. Their application for permanent mooring has been considered only recently due to the uncertainties related to their performance during keying and under sustained and cyclic loading. The paper presents a series of centrifuge tests undertaken to investigate the performance of a model SEPLA in West African soil under monotonic and various levels of sustained and cyclic loading. The testing process mimicked the operation of the anchor and provided insights into (i) the keying of the anchor and the associated loss of embedment, (ii) the combined effect of consolidation and strain softening during sustained loading and the associated loss or gain in capacity and (iii) the cyclic degradation under various levels of cyclic loading. The results and subsequent analytical analysis demonstrate that SEPLAs can be used for permanent mooring, provided that sustained and peak cyclic loads remain lower than 80% of the ultimate monotonic capacity.
Since the introduction of the Suction Embedded PLate Anchor (SEPLA) in 1998, the offshore industry has been benefiting from its ability to be installed at a precise location and resist a high vertical load component in a taut or semi-taut leg mooring configuration, without the needs for a large offshore installation spread as in the case for suction piles. Before 2008, SEPLAs were used as temporary anchors to moor MODUs, for which the industry has a reasonably good understanding from full scale field tests (Brown, et al., 2010) and experimental and numerical research. The keying process was notably thoroughly investigated, experimentally by Wilde et al. (2001), O'Loughlin et al. (2006) and Gaudin et al. (2009) among others, and numerically by Song et al. (2009), Wang et al. (2011) and Yang et al. (2012).
