Model Study of Piled Raft Foundation

Abstract

Raft foundations are used in situations when normal strip foundation occupying more than 50% of building area under the super structure. Piled raft foundation allows the high load bearing capacity and reduces the settlements at very economical way as compared to other conventional foundation designs. By locating the piles strategically results in improving the load carrying capacity of raft and reduction in differential settlement. In present investigation model tests on raft with combination of single pile, (2 × 2) and (3 × 3) pile groups were performed in loose sandy soil and effects of length of pile, alignment and configuration on ultimate load capacity were observed. The model piles and raft are made up of mild steel and model piles used for testing’s are displacement piles having diameter of 6 mm and length of 220 mm, 180 mm, 140 mm were used, these are representing the slenderness ratio of 37, 30, 23 and the raft have a dimensions of 100 mm × 100 mm in plan and with a thickness of 5 mm. The change in load carrying capacity was indicated by load improvement ratio and the diminution in settlement was indicated by settlement reduction ratio. As the number of piles increases the settlement reduction ratio and load improvement ratio increases. Experimental results were compared with result of numerical study and found to be in good agreement with experimental investigation.