Evaluating Parametric Influences on Load-Sharing Behaviour of Piled Raft Foundations

Piled Raft Foundations (PRF) are a popular solution for supporting heavy structures on weak soils, but their design and analysis can be complex due to interaction between subsurface, raft and piles. In this study, finite element analysis is employed to examine the effect of various parameters on the ratio of load-sharing (χ_pr) for a square raft with circular cross-section piles beneath it. The analysis considers a uniformly distributed surcharge applied over the entire top surface of the raft. The parameters varied are spacing to diameter ratio, S/D (2–20), diameter of piles, D (0.4–1.6 m), length to diameter ratio, L/D (8, 12 and 16), and raft-soil stiffness ratio, K_rs (0.069, 0.558 and 1.88). The present study concluded that load-sharing behaviour is good for lower S/D ratio (3–4) and an average pile group to raft width ratio, W_g/W_r of approximately 0.4 or more. The χ_pr improves as L/D increases and this increasing trend is more pronounced at higher W_g/W_r ratio. For an increase in D, χ_pr first increases and after certain point it start decreasing. The results can be implemented to the construction and analysis of PRF for industrial structures, bridges, and tall buildings, among other uses.