Visualization of torpedo pile penetration and pullout in transparent synthetic soil representative of soft marine clays

Fluked (aka finned) torpedo anchors are increasingly being used for tethering of offshore structures. In this study, the effect of the torpedo fluke length on penetration and pullout capacity was explored. Three model torpedoes of equal mass having different fluke shapes were installed in a synthetic transparent soil surrogate used to model soft clay. Images acquired during embedment and extraction provided data for digital image correlation (DIC), from which time-resolved data for anchor movement and soil displacements were obtained. Pullout loads were also measured. The affected zones around the anchors during penetration and pullout were found to be approximately four times the shaft diameter, and were larger where flukes were present. Increasing the fluke dimensions decreased penetration but increased peak pullout loads. Results suggest that the area of the leading and trailing edges of the flukes is responsible for both decreased penetration and elevated pullout capacity for fluked torpedoes.