Experimental and numerical study of piled raft system

Raft foundations are used when isolated footings cover more than 70% of the building area under a super structure. A combination between the use of piles and raft foundation is known as piled raft foundation. Piled raft foundations proved to be more economical in case of high rise buildings on clay and can provide safe bearing capacity and serviceability requirements. The use of strategically located piles improves the load capacity of raft and reduces the differential settlement. This research sheds some light on the philosophy of using piles as settlement reducers for raft foundations and also the behavior of piled raft embedded into sand. Small scale model tests are performed. The effects of pile length and alignment on the attained ultimate load are experimentally investigated. From the accomplished studies, it has been concluded that as the length of piles and number of piles decrease, the load carried by raft increases. Additionally, it is found that the best and the optimal settlement ratio (S/B%) to design the piled raft as settlement reducer is 0.7%.Finally the percentage of load carried by raft at S/B = 0.7% is found to be 39%.