Behavior of Piggy-Backed Drag Embedment Anchors in Marine Soils

This paper summarizes the analytical and experimental results of piggy-backed drag embedment anchors composed of two drag embedment anchors. Drag embedment tests with piggy-backed drag embedment anchors were performed with the spacing between the two anchors at 5.4 fluke length. The experimental results provide a validation of analytical model. The study reveals that: (1) the calibrated piggy-backed prediction model can predict the capacity, trajectory, and pitch of the front and back anchor in the piggy-backed configuration, and (2) the total capacity of the piggy-backed drag embedment anchors can be greater than twice the capacity of an individual anchor because the piggy-back arrangement forces the front anchor to mobilize more rotational resistance than when it is free to rotate as an individual anchor.