Vertical uplift resistance of rectangular plate anchors in two layered sand

Based on rigid block collapse mechanism and employing the upper bound theorem of limit analysis, the ultimate vertical uplift resistance of rectangular plate anchors embedded horizontally in two layered sand has been determined. Closed form analytical expressions were derived for computing the vertical uplift resistance in terms of dimensionless uplift factors F-gamma and F-q, due to the components of soil unit weight (gamma) and surcharge pressure (q) acting on the ground surface, respectively. For given embedment ratios of the anchor, the effect of relative position and thickness of sand layer with higher angle of internal friction (phi(h)) and unit weight (gamma(h)), and sand layer with lower angle of internal friction (phi(l)) and unit weight (gamma(1)), on the magnitude of F-gamma and F-q was studied for different length to width ratio of anchor varying from unity to infinity (square to strip). The solutions obtained from the present theory compare reasonably well with the available data from literature.