Undrained Uplift Capacity of Under-reamed Pile in Layered Clays

Under-reamed piles are generally a choice of foundation for structures subjected to the uplift load, especially for the transmission line towers, patrolling towers, chimneys, tall and slender structures, etc. In the study, the undrained uplift capacity of single under-reamed pile embedded in layered clay is evaluated using finite element (FE) method-based software Plaxis 2D. The geometry of the under-reamed pile is chosen as per the standard codal provision. In the analysis, the soil is assigned with Mohr–Coulomb model and pile is assigned with Linear Elastic model. The thickness of layered clays, i.e., soft clay overlain hard clay and hard clay overlain soft clay is varied with cohesion ratio = 2. The FE results are compared with the solutions available in the literature. The uplift capacity ratio defined as ultimate uplift capacity of under-reamed pile in single clay to that in layered clay having different clay layer thickness ratios (h/H = 0 to 1) is evaluated. The present study results are represented as design charts so as to be used in the design practice.