Effect of Shape of Raft and Relative Density of Sand on Carrying Capacity of Model Piled Raft Foundation

Abstract

A pile-raft foundation proves to be an economical foundation in many situations as compared to a pile foundation, but its analysis is complicated because of interactions between the pile, the raft, and the soil. This research paper presents the experimental study on an axially loaded model raft and piled raft foundation on sandy soil with different shapes of the raft (square, circular, rectangular, and trapezoidal). The study was carried out by varying the relative density of the sand bed (40%, 60%, and 80%). The spacing between piles was kept 7d for all model piled-raft foundations (MPRF). Initial Yield Load (IYL) and Final Yield Load (FYL) of MPRF were calculated as per the Poulos-Davis-Randolph (PDR) philosophy. It was observed that as the relative density of sand increases, the IYL and FYL of piled raft foundations of all shapes increase. The IYL and FYL were observed to increase with an increase in the relative density of sand in the MPRF for all shapes of raft. The higher IYL and FYL were observed mostly in MPRF with a square raft.