4. Conclusions
A series of 3-D numerical analysis were carried out on a large piledraft foundation in a clay soil under the action vertical loading. The effect of pile spacing (Sp), pile length (Lp), pile diameter (dp) and raft-soil stiffness ratio (Krs) on the settlement, load-sharing, bending moment and shear force behavior of the large piled-raft foundation were investigated. Based on the results of the present study, the following conclusions are drawn.
1. For any pile group to raft width ratio, with increase in pile spacing to diameter ratio, average settlement ratio, differential settlement ratio, and bending moment ratio decreases up to the pile spacing of 5–6 times the pile diameter and then increases. Also, load-sharing ratio decreases and shear force ratio increases. Raft with smaller raft-soil stiffness ratio and larger pile group to raft width ratio observed to be effective in decreasing the average settlement ratio. Raft and pile group in piled-raft has carried fewer loads as that of unpiled raft and free standing pile groups.
2. For any pile group to raft width ratio, with increase in pile length to diameter ratio, average settlement ratio, differential settlement ratio decreases and load-sharing ratio increase. Also, the bending moment ratio decreases up to Bg/Br ¼ 0.6 and thereafter it increases, whereas shear force ratio increases linearly.
