الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
The analysis of piled raft foundations has improved over the last few
decades to account for the combined contribution of raft and piles to provide a
more efficient system. In traditional pile-raft systems, piles are connected to the
raft and extend down into more competent soil. While these piles are effective in
increasing the bearing capacity and reducing the structure settlements, they often
lead to significant straining actions at the pile head-raft connection which may
constitute the weakest link.
An attempt to overcome this weak link (pile head-raft connection) is to
disconnect the piles from the raft and to consider these piles as reinforcement to
the subsoil (enhancing its bearing capacity) and at the same time acting as
settlement reducers. Moreover, the gap between the raft and piles is filled with a
cushion of structural fill material. In this unconnected piled raft system, the
cushion acts to redistribute the loads between raft and piles. There are few
previous studies related to unconnected piled raft foundation system that does
not clearly explain the load transfer mechanism and settlement behavior under
static and seismic loading conditions. In addition, the use of unconnected piled
rafts is not common in construction, and foundation design codes do not
specifically address its implementation.
In this study, ABAQUS fmite element analysis software is used to
investigate the load sharing capacity and mechanism of the unconnected system.
The main aim of this thesis is to provide an in depth analysis of the raft-soil-pile
interactions in multi-layer under static and seismic load. The effects of cushion,
piles number, diameter, and length, spacing, raft thickness and all other
parameters are also studied.