Dynamic installation, keying and diving of OMNI-Max anchors in clay

OMNI-Max anchors are designed with the aim of diving upon pullout, gaining capacity with increasing pullout distance. However, this diving potential is yet to be confirmed; that is, the critical question to be resolved is whether or not the anchor dives upon pullout and, if so, in what conditions. This paper reports the results from three-dimensional dynamic finite-element analysis undertaken to provide insight into the behaviour of OMNI-Max anchors during pullout in non-homogeneous clay. Largedeformation finite-element (LDFE) analyses were carried out using the coupled Eulerian-Lagrangian approach, modifying the simple elastic-perfectly plastic Tresca soil model to allow strain softening, and to incorporate strain-rate dependency of the shear strength. The keying process and diving patterns during anchor pullout revealed three governing factors including: (a) pullout inclination angle; (b) padeye offset ratio; (c) final installation depth. For designing anchors to dive into deeper, it was recommended that the anchor loading angle to the horizontal at the padeye should be 45° or less and the anchor padeye offset ratio should be in the range of 0.25~0.53 (offset angle of 14~28°).