Reliability of dynamically-embedded anchors in soft clay

Floating offshore infrastructure requires geotechnical anchorage for station-keeping. Dynamically embedded anchors are anchors that free-fall through the water column and embed in the seafloor through kinetic energy at impact, enabling efficient installation into soft seabeds. Dynamic installation of plate anchors is an alternative to static embedment methods, such as suction-embedded plate anchors. This paper uses a numerical installation and capacity methodology to explore the factors that control dynamically-embedded plate anchor (DEPLA) capacity and to compare DEPLA reliability with that of statically-embedded plate anchors for two sets of seafloor properties that represent different types of geotechnical uncertainty. Probabilistic Monte Carlo simulations are presented for the two representative conditions using the distribution of the tension loads for an example catenary-moored system. The results quantify the smaller influence of soil strength uncertainty on DEPLAs compared to statically-embedded plates. The smaller influence arises due to dynamically-embedded anchors reaching a deeper embedment in softer soil, counteracting the lower strength. This leads to increased reliability compared to statically-embedded equivalent anchors installed to a specified depth. We quantify the reduction in safety factor that could be used for dynamically-embedded anchor design to achieve similar levels of reliability compared to statically-installed anchors of the same size.