ULTIMATE PULLOUT RESISTANCE OF SINGLE VERTICAL ANCHORS

An investigation into the performance of single vertical screw anchors installed in sands is presented. Models were developed employing the limit equilibrium method of analysis to predict the uplift capacity of anchors installed into shallow, transition, and deep depths. An exper imentally observed log-spiral rupture surface was used in the theoreti cal analysis. Shear stresses were calculated on the surface of rupture using Kotter's differential equation. Weight and shear factors for sh allow and deep anchors are established to simplify the calculation of the uplift capacity from the theories developed. These factors are pre sented in simple graphs as functions of the angle of shearing resistan ce of the sand and the relative depth ratio of the anchor. The effect of sand overconsolidation resulting from the application of mechanical compaction was introduced by incorporating the overconsolidation rati o in the uplift capacity calculations. Comparisons between the theoret ical values and the experimental results of the present investigation as well as field results reported in the literature showed good agreem ent.