Buckling and bending response of slender piles in liquefiable soils during earthquakes

Design of pile foundations in seismically liquefiable soils involves identifying the appropriate failure mechanisms. Piles in liquefiable soils are conventionally designed against bending failure due to lateral loads arising from inertia and/or lateral spreading. This is strong evidence that there is another mechanism, which the code does not consider, that may govern the failure of these foundations. In this paper, the response of a single end bearing pile in liquefied soil with and without the effect of axial load has been presented. The effect of liquefaction is incorporated in the pile–soil interaction through nonlinear analysis using the finite difference program Fast Lagrangian Analysis of Continua (FLAC). The method of analysis is carried out using the well documented failure of Showa Bridge piles which failed during the 1964 Niigata earthquake. The response of the pile is also evaluated using dynamic analysis. The need for proper identification of failure mechanisms as well as design guidelines is highlighted.