Vertical Pullout Capacity of a Group of Helical Screw Anchors in Sand: An Empirical Approach

Abstract

In this paper experimental investigations on the behavior of a group of single, double and triple helical screw anchors under the influence of vertical uplift loads are presented. The testing program were conducted on one, two, three and four numbers of anchors in sand for different depths of embedment keeping shallow and deep mode of behavior in mind. It was observed that the pullout load varied significantly with the installation depth of the anchor and the number of anchors. It had been shown that the load displacement relationships for all groups may be reduced to a common curve. The graphs of ultimate pullout capacity a group of two, three and four numbers of anchors with respect to one anchor were plotted and design equations had been proposed to design a group of anchors based on ultimate pullout capacity of one anchor.