Effects of K0 and Overconsolidation on Uplift Capacity

Experimental and theoretical studies on the effects of the coefficient of earth pressure at rest (K0) and overconsolidation ratio (OCR) on the uplift capacity of foundations in sand, with special reference to screw anchors, are presented. Previous contributions on the determination of K0 and OCR are reviewed. Tests are conducted on prototype model screw anchor installed in dense, medium, and loose sands. The sand was placed according to a calibrated placement technique to achieve predetermined relative densities. Vibratory densification was used in compacting the sand, and this resulted in overconsolidated material. The stresses within the sand were measured by stress transducers inside the testing tank. Based on stress measurements, the values of the OCR were determined for all tested depths and sand types. Based on data reported in the literature, a semi‐empirical relationship was proposed to relate the uplift capacities of screw anchors installed in overconsolidated sand to those of anchors installed in normally consolidated sand. Good agreement was observed when present experimental results were compared with results of a theory reported in the literature after incorporating the effect of the overconsolidation.