REZA ZIAIE_MOAYED - Assistant Professor, Department of Civil Engineering, Imam Khomeini International University. Qazvin, Iran
MEYSAM SAFAVIAN - M.S. Candidate of Geotechnical Engineerig, Imam Khomeini International University.Qazvin, Iran

Piled-raft foundations for important high-rise buildings have proved to be a valuable alternative to conventional pile foundations or mat foundations. The concept of using piled raft foundation is that the combined foundation is able to support the applied axial loading with an appropriate factor of safety and that the settlement of the combined foundation at working load is tolerable. Pile raft foundation behavior is evaluated with many researches and the effect of pile length; pile distance, pile arrangement and cap thickness are determined under vertical or horizontal static and dynamic loading. In the present paper the behavior of pile raft foundation with different pile diameters are evaluated under unequal vertical loading. The obtained results showed that the total and differential settlements of pile raft foundation could be reduced with using piles with different diameters.

Pile raft foundation, Different pile diameter, Vertical settlement, Gravelly soils