Uplift behaviour of helical anchors in clay

Helical anchors have been used widely as foundations for transmission towers and pipelines to resist uplift loadings. In this paper, the undrained uplift behaviour of helical anchors in clays is studied using the centrifuge model test and a “large deformation finite element” (LDFE) approach. Nine model anchors were tested in a geotechnical beam centrifuge, with different combinations of the number of helical plates, plate spacing, and embedment depth. The numerical solutions from the LDFE approach are then compared with the centrifuge data and semi-theoretical solutions. Additional LDFE analyses are undertaken to understand the failure mechanisms of multi-plate anchors and applicability of existing semi-theoretical methods. By considering the combined influences of embedment depth, plate spacing, and soil strength profile, a simple procedure is further presented to predict the uplift capacity of helical anchors.