Keying Process of the OmniMax Anchor Shallowly Embedded in Undrained Normally Consolidated Clay

Abstract

The OmniMax anchor is an efficient anchoring foundation due to its dynamic installation and diving property. When subjected to pullout loading, the anchor is keyed to a new orientation and position to provide holding capacity. However, the trajectory and capacity mobilization of the OmniMax anchor during its keying are still unclear, especially for anchors with shallow embedment depth. The present study investigated the keying process of the OmniMax anchor by using a plasticity model. The anchor yield envelope was established based on a shallowly embedded OmniMax anchor with a tip embedment depth of 1.5 times the anchor length. A series of parametric studies were subsequently carried out to investigate the effects of the soil strength gradient, the padeye offset and padeye eccentricity, the pullout angle at the mudline, and the chain parameters on anchor trajectory and capacity mobilization. The anchor ultimate embedment depth and, hence, the ultimate capacity in the final keying stage were discussed. To keep efficient diving property and high capacity simultaneously, it is recommended that the padeye offset angle should range from 15° to 25°, and the pullout angle at the mudline should be no more than 3°.