Embedment Depth Influence on an Uplifting Anchor

This paper presents an experimental investigation on the influence of embedment depth on the anchor failure mode. It is widely understood that a deep anchor will behave differently compared to a shallow anchor. A test set-up is developed in this research to capture soil deformation during anchor uplifting, which consists of a camera, a loading frame, a Plexiglas mould, and a computer. A series of model tests are performed to investigate the influence of the anchor embedment depth on soil deformation. A set of images are captured while a semicircular anchor is being uplifted against the Plexiglas window. A soil displacement field is calculated from two images using the Digital Image Correlation (DIC) method. The failure surface is studied by locating the maximum shear strains deduced from the soil displacement field. Based on this study, it is found that the anchor behaviour is substantially influenced by the anchor embedment depth. A similar punching failure mode is observed in loose sand regardless of the anchor depth. However, in dense sand a restrained failure mode is observed in a deep anchor opposite to the mode with failure plane extending to ground surface in a shallow anchor. This study improves the understanding of soil-anchor interaction and helps to design an efficient anchor system.