الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
A common approach for ground improvement of soft soils is installing stone
columns to increase the bearing capacity, reduce the settlement, and
accelerate the consolidation time. However, stone columns may not have
sufficient capacity in very soft formations due to the lack of confinement of
the enfolding soft soils
The intrusion of soft clay into the column aggregate also hinders the effective
drainage function of the columns. An ideal solution for the above-mentioned
shortcomings is to include geosynthetic encasements around columns. The
encased stone columns have been recently increasingly used in place of the
uncased columns. However, the available geotechnical literature covering
this relatively recent improvement technique is still not fully mature to
completely assimilate the varied factors influencing this technique. This
study uses a three-dimensional finite element analysis to evaluate this
technique’s performance and parameters for different column configurations
and geotechnical conditions. A published well-instrumented case study for a
test embankment is utilized to validate the model for the parametric analyses.
The extensive measured data, including vertical and horizontal
deformations, excess pore water pressure, and geosynthetic tensile stresses,
are used in the validation process. The model was also adjusted to match an
established analytical method that covers specific limited cases; the model
results partially agreed with the analytical solution. A parametric study is
conducted to address the impacts of the different influential factors,
including the column diameter, the stones’ modulus of elasticity and friction
angle, the geosynthetic encasement length and ring tensile modulus, and the
working platform thickness. It was concluded that by increasing the
diameter, modulus of elasticity, friction angle, geosynthetic length, and geosynthetic ring tensile modulus, the settlement under the embankment
nonlinearly decreases, and the time needed to reach the final settlement
decreases with different influences of each parameter. The results are
presented in graphs to allow the geotechnical practitioner to best exploit this
technique by optimizing the configuration and the parameters of the encased
columns using the presented results.