Effect of the Length of a Torpedo Anchor on Its Vertical Holding Capacity

Since its introduction in 1996, the torpedo anchor has built a reputation for itself as a simple and cost effective deepwater anchoring solution. While numerous field tests and numerical research has been done to verify the torpedo anchors holding capacity under various load and soil conditions, the effect of the geometry of the anchor itself on its holding capacity has not been properly identified. This research attempts to improve the database of knowledge regarding the torpedo anchor. Specifically, the research objectives are i) to evaluate the vertical holding capacity of torpedo anchors using analytical and numerical methods and ii) to analyze the correlation between the total length of a torpedo anchor and its vertical holding capacity. The numerical method uses a 2-D axisymmetric model to evaluate the vertical holding capacity with respect to varying total lengths. Both the soil and anchor were simulated as homogeneous, isotropic linearly elastic materials using plane elements capable of demonstrating non-linearity and large displacement behaviour. The non-lienar interaction between the anchor and soil is also modelled using contact finite elements that allow relative sliding and detachment between the two surfaces in contact. Results from the numerical analysis is compared with analytical calculations using a variation of the ultimate load bearing capacity equation for conventional piles to suit the use for torpedo anchors.