Uplift resistance of strip and circular anchors in a two layered sand

The vertical uplift resistance of shallow strip and circular plate anchors buried horizontally in a two layered sand has been determined by using the upper bound theorem of limit analysis. Uplift factors f(y) and f(q) due to the effects of soil unit weight and surcharge pressure, respectively, have been established. For a given thickness of the two layers, the uplift factor f(y) is found to be comparatively greater when the anchor is embedded in dense sand underlying a loose sandy layer. However, the factor f(q) remains unaffected by the layers' relative positions. As compared to available experimental results, the theory provides a slight overestimation of the uplift resistance especially for greater embedment ratios.