Dynamic installation of offshore torpedo anchors in spatially variable clay

The use of self-penetrating torpedo anchors is gaining increasing popularity in practice. Whilst many research works have been undertaken concerning its dynamic installation, the vast bulk of them are deterministic in nature. This article presents three-dimensional large deformation random finite element analyses with proper consideration of strain rate and strain softening effects to probe into the anchor penetration mechanism and embedment depth in spatially variable seabed. The random heterogeneity of undrained shear strength is approximated as a non-stationary random field. Numerous realizations of the random field are passed to Coupled Eulerian-Lagrangian finite element program within the Monte-Carlo framework to analyze the stochastic behavior. The influence of spatial variability is found to be most significant when the torpedo anchor enters the deceleration stage. The ultimate embedment depth reflects the accumulated strength of soil lying in the penetration trajectory. The dispersion of stochastic results is much affected by the coefficient of variation the of random strength field. A reliability-based design approach is eventually developed, where a factor of safety is introduced to provide a safety margin against spatial variability. This is likely helpful for engineers to select appropriate safety factors based on the guaranteed rate required for specific projects.