Piled raft with gap between pile top and raft to adjust differential settlement

A new type of piled raft was developed with the gap between pile top and raft.It could be adopted to adjust the raft-pile-soil interaction and to reduce differential settlement of buildings.Model tests on piled raft in sand with and without the gap between pile top and raft were carried out.It was shown that the sand among piles with the gap between pile top and raft was compacted earlier than that of coventional piled raft foundation under the same load.The compaction of sand among piles could increase the load carried by soil and at the same time reduce the penetration of pile tip.This would make piles and soil settle together.Piled raft with the gap between pile top and raft could mobilize the bearing capacity of soil effectively,in the meantime reduce the stress concentration at pile top and enhance the bearing resistance of pile tip.