The Effect of Cavity on Vertical Bearing Performance of Torpedo Anchors

Abstract Cavities may form above the tail of torpedo anchors after installation and can significantly influence their subsequent vertical pullout behavior. However, there is still a lack of deep understanding of the effect of a fully open cavity on the vertical pullout capacity of torpedo anchors. This study investigates the vertical pullout capacity of torpedo anchors with a fully open cavity using the coupled Eulerian–Lagrangian (CEL) method implemented in abaqus. A comprehensive parametric analysis was conducted considering the impacts of anchor aspect ratio, fin aspect ratio, embedment depth, and soil strength profile. The results indicate that cavities reduce markedly both the end bearing and shaft friction resistance by altering the soil flow near the anchor tail, and thus affecting the anchor vertical bearing capacity. A capacity reduction coefficient β, defined for quantifying the loss in capacity due to the cavity, is found depending primarily on the shaft and fin aspect ratios. Specifically, β increases logarithmically with the shaft aspect ratio and decreases exponentially with the fin aspect ratio, while it is insensitive to embedment depth and soil strength gradient. Based on these findings, a simplified design procedure is proposed to predict the vertical pullout capacity considering cavity effect for engineering design in practice. This work improves the understanding of soil flow behavior influenced by cavities and provides a practical method to enhance the reliability of torpedo anchor design under vertical loading.