Abstract: During installing procedures of torpedo anchors, tip-shape of the torpedo anchor affects penetration resistance and depth. In this study, the lower bound method of the plastic limit analysis theory is used to analyze the penetration resistance and penetration resistance coefficient for different aspect ratios of the elliptical-tip of torpedo anchor (ξ), embedment depth, and friction coefficient of anchor-soil. A series of results is obtained: 1) If a soil-anchor interface is smooth, the penetration resistance coefficient decreases with increasing the aspect ratio of torpedo anchor tip; for the rough interface of soil-anchor, the penetration resistance coefficient increases with increasing the aspect ratio. 2) The influence of the friction force markedly increases with increasing ξ due to a larger interfacial area. 3) With increasing embedment depth, the friction coefficient reduces gradually, which corresponding penetration resistance coefficient is minimally impacted by various ξ. 4) If the friction coefficient ? is larger than 0.75, the anchor tip with the aspect ratio less than 1 responds to smaller bearing capacity; and while the friction coefficient is less than 0.26, the smaller bearing capacity is provided by the anchor tip following aspect ratios greater than 1. The lower bound results of ξ = 0 and 1 show good consistent with the previous solutions for strip foundation and circular structure, which verify the lower bound method of elliptical-tip of the torpedo anchor is reasonable.

Key words: torpedo anchor, elliptical tip, undrained shear strength, clay, embedment depth