Torpedo anchors are increasingly popular for tethering of floating structures. Six model torpedoes of equal mass but different fin shapes were installed to investigate the effect of fin shape on the depth of penetration, pull-out capacity, and soil-structure interaction. A transparent soil surrogate was employed to simulate marine soft clay and to visualize the soil's response during penetration and pullout. Torpedoes penetrated the model at a velocity of approximately 5 m/sec. Digital Image Correlation (DIC) was employed to analyze images of both the penetration and pullout events. First, internal soil deformations were obtained using DIC. Next, strains and particle trajectories were derived using in-house routines. The effective zones around torpedo anchors where deformations can be resolved during penetration and pullout were determined. Preliminary results suggest that the torpedo shape materially influences the depth of penetration. Using fins decreases the penetration depth by 10 to 35% compared to finless torpedo, depending on fin geometry. Additionally, the pullout capacity of these anchors depends mainly on their embedment depth, self-weight, and interactions with the surrounding soils. In particular, pullout capacity increased by 33% and 54% for torpedoes with fins’ length of 0.325L and 0.65L, respectively compared with finless torpedoes.
Abdelazis Ads, Mehdi Omidvar, Stephan Bless and Magued Iskander
Keywords: torpedo, fin, fluke, offshore, marine clay, pull-out, transparent soil
Publisher: DFI