The applicability and load-sharing behavior of piled rafts in soft clay: experimental study

The research purpose is to study the applicability and the load-sharing behavior of piled rafts in soft clay. An experimental program was conducted on un-piled rafts (URs) and piled rafts (PRs) in soft clay. The soft clay was prepared with kaolinite. The model rafts and piles were square steel plates and steel hollow pipes, respectively. The applied load, raft settlements, pile axial forces, and raft contact pressures were measured. The effects of pile shaft resistance, pile spacing, and placing a sand cushion above soft clay on the ultimate capacities, settlement reduction, and load-sharing behavior are presented and discussed. The results clarified that piled rafts are effective in soft clay due to the efficiency in decreasing settlement and enhancing the ultimate capacity. For load-sharing behavior, at first, both raft and piles resist the load, then raft capacity is fully mobilized thereby exerting extra loads on piles. It was also observed that percentage of load carried by piles increases with increasing pile shaft resistance, whereas the percentage of load carried by the raft increases with increasing the pile spacing, or the thickness of the sand cushion.