Centrifuge modelling of helical anchors in sand

Many structures are subject to overturning forces caused by natural processes such as wind action, or tidal action. Traditional methods of resisting these forces called for massive foundations to be built. The size of these foundations often makes them very expensive. This has led to the use of various soil anchors, like helical anchors, to resist uplift forces. Several theories for estimating helical anchor uplift resistance have been developed. However little field testing of these theories has been conducted. The purpose of this study was to use centrifuge modelling of helical anchors to verify one of these theories. A secondary aim for this study was to develop a cone penetrometer for use in the centrifuge.; Anchor pull-out tests were completed using a two-helix anchor embedded in loose and dense soil samples. Anchors were embedded at shallow depths and pulled. The anchors were installed and pulled in-flight. The results indicate that the theory is conservative for helical anchors embedded in dense sand, but it tends to over-predict uplift capacity for anchors in loose sands.; A 8 mm diameter cone was built. Cone penetration tests were performed to determine sample uniformity and mobilized angle of friction. Cone penetrometer tests results indicated that the samples were relatively uniform. The mobilized angle of friction for dense and loose sand were calculated using Randolph's Method.