Vertical uplift capacity of horizontal anchors using upper bound limit analysis and finite elements

The vertical uplift capacity of strip anchors embedded horizontally at shallow depths in sand is examined by using an upper bound limit analysis in conjunction with finite elements and linear programming. Velocity discontinuities were allowed along the interfaces of all the elements. The plastic strains within elements were incorporated by using an associated flow rule. The collapse load was expressed in terms of a nondimensional uplift factor Fγ, which was found to increase continuously with an increase in both embedment ratio (λ) and the friction angle (ϕ) of sand. Even though the analysis considers the development of plastic strain within all elements, however, at collapse, the soil mass just above the anchor was found to move as a single rigid block bounded by planar rupture surfaces making an angle ϕ with the vertical. The results were found to be almost the same as reported in the literature for those based upon a simple rigid wedge mechanism.