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During the pile drivings of three precast concrete piles of
the Chiayi-Taipo Large Scale Pilot Pile Test for the High Speed
Rail Project, a network of piezometers, inclinometers and level
posts were deployed around the pile driving area to monitor the
variations of soil water pressure and the ground deformations
induced by pile drivings. Each of the piles driven has a
diameter of 80cm and a length of 34m. The results measured have
clearly revealed, qualitatively and quantitatively, the
squeezing phenomenon and its influencing area during the
penetration process of the piles. Besides, the correlation
between the resistance of pile driving and the geological
condition of the site has also been identified. The results of
measurement are very valuable and useful for engineering
applications. It is shown that in the vicinity of the pile
,very high excess pore pressure are developed, it approaching
1.5 times the in-situ vertical effective stress in sand and 3.5
times in clay and beyond 15 times pile diameters the excess pore
pressure are virtually negligible. The time of dissipation of
excess pore pressure in sand is about 3.5 minute and 18 hours in
clay. To predict the maximum excess pore pressure, the measured
results in clay agree well with the empirical method proposed by
Massarsch or Ladanyi and the results in sand agree well with
that proposed by D'Appolonia and Lambe. We also can get good
result from the "Cavity Expansion Theory" in both clay and sand
if we can choose the parameter carefully. If simulating the
lateral deformation with "Elastic Theory", the decreasing trend
is siginificantly different with the field measured value.
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