A Comparative Study on the Uplift Capacity of Single Helix Helical Anchor and Granular Pile Anchor in Sand

Helical anchors are tension members widely used to provide tension resistance to structures that are prone to uplift. A relatively new method called granular pile anchor is a modified form of a conventional stone column with an anchor plate at the bottom connected to an axial rod that can provide tension resistance when connected to the base of a structure footing during uplift. In this paper, experimental investigations on the uplift behavior of laboratory-scale model helical screw anchors and granular pile anchors installed in loose sand bed under the influence of vertical uplift loads are presented. The model anchors were subjected to a constant uplift strain, and the uplift resistance and the uplift displacement were measured during the experiment. The model helix/anchor diameter was kept as a constant of 70 mm, and the effect of embedment ratio (length to diameter ratio) on the uplift capacity and uplift behavior are studied and reported. A granular pile anchor was found to provide significantly larger uplift resistance compared with a single helix helical anchor and may be used as an alternative or in addition to it.