Numerical Simulation of Installed Torpedo Anchors Embedded in Cohesive Soil

Abstract

Torpedo anchors have proven to be one of the most important alternatives for mooring systems, especially in Brazilian offshore fields. Their installation involves many hydrodynamic and soil-structure interaction aspects and, therefore, their vertical stability cannot be always assured. This often results, after their installation, in an inclination between the anchor and a vertical axis called tilt angle. The traditional approach to assess the holding capacity of torpedo anchors relies on the hypothesis that the relative angle between the load direction and the axis of the anchor may be used in conjunction with a finite element model in which a perfectly vertical anchor is considered. In this work, this assumption is discussed. A parametric study in which four different tilt angles are combined to various load inclinations was conducted. The study relied on a previously proposed FE model. The results obtained indicate that the use of the traditional approach is safe for relative angles higher than 40° and lower than 140° For other angles, the approach leads to values slightly higher than those predicted with the direct consideration of the tilt angle.