Three dimensional analysis of piled raft foundations in alluvial soils

THREE DIMENSIONAL ANALYSIS OF PILED RAFT FOUNDATIONS IN ALLUVIAL SOILS SUMMARY Keywords: Raft; Mat; Piled raft foundation; Alluvial soil; Dense sand layers; Three dimensional finite elements, Pile group to raft width ratio. This thesis has been prepared in partial fulfilment for the degree of Doctor of Philosophy in the Department of Civil Engineering of the Graduate School of Sakarya University. The aim of this study was to show the possibility of constructing tall buildings on 'weak' alluvial soils of the city of Adapazarı by using piled rafts and determine the most convenient number, dimensions and spacing of piles. In this study, three dimensional models of piled rafts were generated and calculated with the geotechnical finite element code PLAXIS. After evaluating around 600 borings and 250 soundings performed in the city, soil profiles which have dense sand and gravelly sand layers were located. Analyses have been performed for a typical profile to establish guidelines for the diameter and spacing of the piles as well as the type of the raft. The main finding of the thesis is that the ratio pile group width to breadth of the raft is the governing parameter in design and analysis of piled rafts. xv