A drag anchor is a marine foundation element, which is penetrated into the seabed by dragging in order to generate a required capacity. The holding capacity of a drag anchor in a particular soil condition is developed by soil resistance acting on the anchor. This capacity also includes the resistance developed by the anchor line in the soil.
This study is concerned with the collection of measured data and an evaluation of existing prediction methods for capacity and penetration depth of anchors embedded in clayey soils. Both vertically loaded anchors (VLA) and drag embedment anchors (DEA) are considered in this study. Test data from six different sites where anchors have been tested or employed for projects have been collected as a basis of comparison between existing prediction methods and field measurements.
Theoretical methods proposed by Stewart (1992) and Neubecker and Randolph (1996b) are considered as well as empirical solutions developed by the Naval Civil engineering Laboratory (NCEL) and anchor manufacturing companies, Vryhof and Bruce. It is concluded that the existing prediction methods exhibit considerable variability compared with measured penetration depths and capacities depending on the type of anchor (VLA and DEA).
To better understand and to precisely approach the anchor performance, a new approach, Murff (2001), employing upper bound plastic limit analysis is described as a promising approach for further study.