Mohsen Zokaei - Geotechnic M.S student, Civil engineering college, Shahed university, Tehran
Mahmood Qazavi - Professor, Civil engineering college, Geotechnic engineering department, Khaje Nasiredin Toosi university,Tehran

Generally the use of piles under the shallow foundation resulting in improved load-settlement behavior. But, due to high stress concentration, especially in the area of the raft and piles applies connection, nowadays the cushion layer of dense sand or gravel is widely used in the area under the raft. The purpose of this study is to evaluate the effect of the cylindrical cushion on load-settlement behavior of piled raft with PLAXIS 2D software. results show that the load-settlement behavior of a non-connected piled raft with cylindrical gravel cushion has no significant difference from pile group that has continuous cushions. And it is economical to use cylindrical cushions with a diameter approximately equal with the diameter of pile used instead of the continuous gravel cushion. And results showed an improvement in the behavior of disconnected piled raft with cylindrical cushions by increasing the number of piles

piled raft, cylindrical cushion, load-settlement, PLAXIS 2D