An Experimental Study on Behaviour of Piled Raft Foundation: Fid-Bau Portal

An Experimental Study on Behaviour of Piled Raft Foundation

Patil, Jaymin D. / Vasanvala, Sandeep A. / Solanki, Chandresh H.

Abstract In order to study the behaviour of piled raft foundation system in sandy soil under vertical load, an experimental program in the laboratory has been conducted. The experimental program includes the model test on unpiled raft, raft supported by single pile, (2 × 2) and (3 × 3) pile groups. The piles used in this test are non-displacement piles. In the laboratory test, model mild steel piles of diameter 20 mm and a length of 200 mm were used, to represent the slenderness ratio, L/D of 10. The raft was made of mild steel plate with plan dimensions of 200 mm × 200 mm with different thicknesses of 5, 10 and 15 mm. The values of raft-soil stiffness of model rafts ranging from 0.37 to 10.11 covers flexible to very stiff raft. The refinement in the bearing capacity is represented by load improvement ratio and the reduction in average settlement is represented by settlement reduction ratio. The influence of raft-soil stiffness and the number of piles underneath the raft on the 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 from 1 to 9 piles, the load improvement ratio increases by 30–40 %, settlement reduction ratio increases by 18–90 % and percentage of load carried by the raft decreases by 22–25 %. Also load improvement ratio is slightly increases by 1.5–5 % and the settlement reduction ratio decreases by 1.5–30 % as the raft-soil stiffness ratio increases for the given number of piles, while the load carried by the raft slightly decreases by 1.5–4.5 % as the raft-soil stiffness increases.