الفهرس 
Methodology
Model VerificationOnly 14 pages are availabe for public view
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Abstract
Piles are one of the widely spread used systems to transfer high level of stresses to
deeper soil strata when the subsurface strata cannot bear the needed stress level. Piles are
commonly connected using a raft to maintain group action and to ensure overcoming
any expected differential settlement. Although the raft is in direct contact with the sub-
surface strata, conventional design systems ignore the load transferred from the raft to
the soil due to this contact and encounter on the pile group bearing capacity and
settlement. This system is named as pile group system.
The behavior of piled raft system depends on many factors starting from the behavior of
single pile (pile-soil interaction) to the raft-soil interaction and the pile-soil-pile
interaction. This fact highlights the importance of studying single pile load transfer
mechanism prior to the study of group action to be able to validate the main parameters
used in modeling.
For the sake of validating the software package used and the estimation of the different
input parameters needed for the modeling of different pile group system, a pile load test
that was performed on ALZEY Bridge in Germany conducted by Sommer &
Hammabach (EI-Mossallamy 1999) was chosen to be numerically modeled and the
analysis results were compared to the results obtained from field. Different parameters
affecting the pile-soil interaction were examined and compared to the field results to
select the most representing parameters for the shaft interface and the pile tip interface
element simulating the real behavior of the pile in the field
To study pile group action and the effect of the raft contact in the piled raft system, pile
group was modeled with and without full raft contact with the soil. Calculated loadsettlement
curves for both systems were compared. Moreover load-settlement curves of
different pile positions were investigated to study the effect of pile arrangement
(position) on the load transferred by the pile. Studying the effects of piles spacing and
length to diameter ratio was also conducted to evaluate the different parameters affecting
the piled raft system. Finally, the capacity of selected piled rafts were examined and
compared to the procedure suggested by Poulos (2002).