| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 94 === ABSTRACT
Both preloading and Prefabricated Vertical Drain (PVD) are
methods of ground improvements. Thy are widely used for improving
soft clay. The purpose of this research is to simulate the behavior PVD in
soft clay layer by using Finite Element code PLAXIS. The vertical drain
function has not been built-in in PLAXIS. The main topics of study
include: 1) the influence of PVD installation depth upon consolidation
settlement; 2) the influence of PVD spacing on consolidation settlement;
3) the influence of smear effect on consolidation settlement; 4) the
influence of well resistance on consolidation settlement; 5) case study of
preloading and vertical drain in Second Bangkok International Airport
(SBIA).
The findings indicate: 1) provided the installation depth of PVD is
over 85% of the thickness of improving ground, shortening the distance
of PVD can increase the consolidation rate; but if the PVD installation
depth is below 85% of the thickness of improving ground, there is no
remarkable effect by shortening the spacing of PVDs; 2) concerning with
the influence of smear effect, when kh/ks=2, the influence caused by
increasing s is limited; but when the kh/ks =10, the influence caused by
increasing s will increase; 3) the excess pore water pressure inside the
PVD does not equal to zero, and the higher the well resistance , the higher
is the excess pore water pressure; 4) the estimated consolidation
settlement curve and excess pore water pressure dissipation curve of the
case study are consistent with the observed curve.
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