الفهرس 
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Abstract
of the new innovated piling systems and to preserve safe and economic design,, full implementation
and understanding of the installation parameters are highly crucial. Nevertheless, the designers
always face the problem that the same pile installed in the same subsurface conditions even using
the same machine, originate different load-settlement curves for the same geometry of the pile
”length and diameter” . Such phenomenon sheds an obscure atmosphere and obliges the designers to
choose the conservatism trend in assigning the. pile bearing capacity, it might distracts the
foundation engineer to the point that overestimation of pile capacity can occur. This phenomenon
was mainly attributed to the method of pile installation and to the experience and skill of the
operating crew which was regarded before as a subsidiary parameter.
The aim of this research is directed towards investigating, through in-situ testing,
observations and analytical modeling, the behavior of piles during installation and the associated
influence degree in the surrounding soil, how much enhancement in the soil properties can be
attained, and how far is improper installation can emerge related to the single pile and the whole
pile group. The research focuses mainly on bored piles, continuos flight auger piles ”CFA” and new
screw piles of large stem diameter recently developed in the last ten years.
The research was founded on two main parts, the first part is in-situ work, which involved a
numerous sounding test using cone penetration tests prior and after pile installation, besides, it
involves undertaking of pile loading tests on piles which the author of this research was involved
as an inspector and supervisor. Complete in-situ observations were recorded for subsequent
analysis.
The second part is a numerical implementation of the pile-soil interaction problem, it has been
undertaken by establishing an analytical model using an axi-symmetrical finite element program and idealizing the interface between the soil and the pile employing joint
interface
element. The model simulates in a phased step-wise procedure the detailed installation of bored and
screw piles. Moreover, comparison between assembled in-situ testing results, observation records
and the numerical modeling results had been conducted where a consistent matching are
substantiated.
Eventually, a parametric study has been conducted to accentuate the influence of the constructional
parameters on the single pile and the global group of piles. The analytical model was implemented
to reveal the substantiality of good performance of piles reflecting the consequences incurred from
professional and improper installation.