Experimental investigation of uplift behavior of anchors and estimation of uplift capacity in sands

Anchor plates have been widely used in geotechnical engineering due to their good uplift resistance. Small-scale pullout model tests on anchors with various geometries in dry sands are carried out to investigate the influences of type and dimension of anchors on the uplift behavior. The experimental results show that there is no distinct difference of uplift capacity between helical anchor and circular plate anchor with the same diameter and embedment depth. The breakout factors of anchors with a diameter of 50 mm are slightly lower than those with a diameter of 20 mm, and their dimensionless failure displacements are obviously higher than those of anchors with a smaller diameter. The critical embedment ratios of anchors in medium and dense sand are determined based on the relationships of dimensionless failure displacement and embedment ratio, which is used to postulate failure surfaces of shallow and deep modes considering previous experimental results. Accordingly, theoretical formulas for uplift capacity are deduced by means of limit equilibrium analysis. The comparisons between theoretical values and experimental results demonstrate the accuracy of theoretical formulae.