Full-scale lateral load tests on a group of bored and a group of driven pre
cast piles were carried out as part of a research project for the proposed
high-speed rail system in Taiwan. Standard penetration tests, cone penetrat
ion tests (CPT), and Marchetti Dilatometer tests (DMT) were performed befor
e the pile installation. The CPT and DMT were also conducted after pile ins
tallation. Numerical analyses of the laterally loaded piles were conducted
using p-y curves derived from preconstruction and postconstruction DMT and
by applying the concept of p multipliers. Comparisons between preconstructi
on and postconstruction CPT and DMT data and evaluation of the results of c
omputations show that the installation of bored piles softened the surround
ing soil, whereas the driven piles caused a densifying effect.