As a matter of fact, piles are similar to slender columns that soil around them act as a lateral
support. Those piles situated in liquefiable soil layers undergo lower lateral forces because of
liquefaction due to seismic ground motion. In this case pile has potential of axial instability like
unsupported columns and this phenomenon can constitute lateral buckling of piles in the weak
direction and result in plastic hinges in the pile’s body. A lot of failure in the piles has been
reported because of earthquake and liquefaction of soil layer while these piles had been
designed based on creditable codes like JRA and NEHRP. So it seems that the behavior and
analysis methods of piles are still unknown. This research attempts to predict the buckling
capacity of piles in layered liquefiable soils, using a numerical method in which Rayleigh-Ritz
approach was employed to minimize total potential energy. Furthermore an expression has been
introduced to calculate effective buckling length of pile in liquefiable soils. By mean of this
methodology the buckling capacity of pile could be obtained while the stiffness of pile and soil
are given. This methodology can also be applied to extended pile shafts in bridge.
Keywords: pile, buckling, total potential energy, liquefiable soil, effective length