An experimental investigation on behavior of piled raft foundation

An experimental program in laboratory is conducted on model piled rafts in sand soil. The aim of the experimental program is to study the behaviour of piled raft foundation system subjected to vertical load. The experimental program includes the model test on unpiled raft, raft supported by single pile, (2x2) and (3x3) pile groups. The model piles used in this test are non displacement piles. In the laboratory test, model mild steel piles of diameter 10mm and length 200mm were used, represents slenderness ratio, L/D of 20. The raft was made of mild steel plate with plan dimensions of 160mm x 160mm with different thicknesses of 5mm, 10mm and 15mm. The refinement in the bearing capacity is represented by load improvement ratio and the reduction in settlement is represented by settlement reduction ratio. The influence of number of piles and raft thickness on load improvement ratio and settlement reduction ratio are presented and discussed. The results of the tests show that as the number of piles underneath the raft increases, load improvement ratio and settlement reduction ratio increase and percentage of load carried by the raft decreases. Also, there is a negligible effect on load improvement ratio and settlement reduction ratio with increase in raft thickness, while raft thickness has a minimal effect on the load carried by the raft.