Interaction domains of piled raft foundations in cohesive soils under vertical-eccentric loads

Due to a poor understanding of the piles-raft-soil interaction mechanisms at failure and the consequent lack of rational and generally accepted load-sharing criteria, the design of piled rafts under combined loads is typically performed neglecting the contribution of the connecting raft to the overall capacity of the system, often leading to overly conservative designs. To fill this gap, for the first time, this paper proposes analytical solutions based on the bound theorems of limit analysis to compute the failure domain of piled rafts under vertical eccentric loads. An extensive numerical study was carried out to understand the main factors governing the behaviour at failure of piled rafts embedded in cohesive soils in undrained conditions. As expected, the raft can play a crucial role in terms of both vertical and moment capacity, so that ignoring its contribution causes design inefficiencies, with unnecessary economic and environmental costs. Comparison of the analytical solutions with the numerical results showed that the proposed theoretical methods effectively capture changes in system capacity due to different piled raft configurations.