Anchor Behavior in Sand

This paper describes an experimental investigation of the behavior of isolated anchors and groups of anchors in sand. It is concerned with medium scale laboratory tests. It is concluded that the ultimate pull out resistance of an anchor in sand depends on the standard variables such as diameter, depth of embedment, and sand density as reported by others, but also on the stress history of sand. Carefully controlled tests show that overconsolidation of the sand increases pull out resistance several fold. Quantitative measurements of sand movements near to the anchor were made. Prestressed anchors behave in a very different manner than dead anchors and test data quantify these differences. In groups, anchors interact. Generally the ultimate pull-out loads were less than those of an equal number of isolated anchors. Load distribution amongst the anchors was initially near uniform but with load increase the outer anchors carried larger loads than the central anchors. Movements of the group generally were greater than those of an isolated anchor, and depended primarily on applied load level.