A model study of negative skin friction on a fixed base pile in soft clay
Abstract
In this research programme, a small-scale laboratory
test was carried out to investigate the phenomenon of
negative skin friction through studying the interaction
between a pile and the surrounding soil and to obtain, by
means of an instrumented 50mm diameter model pile, an
expression for the magnitude and distribution of negative
skin friction for an end-bearing pile in soft clay. The
programme included measurements of pore water pressures
using miniature piezometers, both vertically along the
pile shaft and laterally from it, as the pattern of
dissipation of this pressure controls the distribution of
negative skin friction along pile length at any given
time.
Two testing programmes were conducted. Each testing
programme consisted of applying load increments on the
soil up to 90 kPa as surcharge pressures. Pore pressures,
settlements and pile loads were monitored until 90%
consolidation had been achieved.
From test results, expressions relating the surcharge
pressure and soil shear strength with the developed
negative skin friction have been established.
The study has been extended to include predictions of
negative skin friction and pore water pressures by the use
of Numerical Methods such as the Finite Element Method and
the Finite Difference Method. Results obtained by these
methods have been compared with those measured.