Helical Anchors in Dry and Submerged Sand Subjected to Surcharge

Abstract

The influence of surcharge and submersion of sand on the uplift performance of a single helical screw anchor is presented. An experimental investigation is conducted on shallow anchors installed in dense dry and submerged sands subjected to a surcharge intensity of 7.35 kN/m2. Test results are compared to those of anchors installed in sands with free surface. The application of a surcharge on the sand surface results in an increase in the uplift capacity of shallow anchors. For both dry and submerged sands, the contribution of the surcharge to the uplift capacity decreases with the increase of the embedment depth of the anchor. A normalized factor is established to express the applied surcharge in terms of the acting overburden pressure. Nondimensional equations of the parameters affecting the uplift capacity and the intensity of the applied surcharge were proposed. It has been shown that the negative effect of submersion on the anchor's pullout capacity can be offset by applying surcharge on the sand surface.