Shaking table testing of two single piles of different stiffnesses subjected to liquefaction-induced lateral spreading

Abstract

Lateral spreading is the main cause of pile foundation damage in liquefaction-prone areas during earthquakes. A soil profile in which a non-liquefied soil is on top of a liquefied soil is a critical design scenario. To investigate the influence of lateral spreading on pile responses in this type of soil profile, a shaking table test was performed on two single piles in the ground with a 2° slope. Considering different pile stiffnesses, an aluminum pile (Al pile) and a polypropylene pile (PP pile) were tested. The piles were embedded in multilayered soil comprising a clay layer sandwiched between dry sand above and saturated sand below it. The two piles had considerably different displacement and moment responses to an input motion based on a 1999 Taiwan Chi-Chi earthquake record. The experimental lateral spreading soil displacement profile approximated the cosine profile proposed by Tokimatsu and Asaka. Compared with the upper non-liquefied soil, the magnitude of the lateral spreading pressure of the liquefied soil was small. The experimental lateral spreading pressure from the non-liquefied soil layer was approximately 2.1 and 4.5 times Rankine's passive earth pressure for the PP and Al piles, respectively. The difference between the derived p-y curves of the Al and PP piles for the non-liquefied soil layer may have been due to the contribution of downhill soil reactions. To reflect the influence of pile stiffness, both the downhill and uphill p-y curves of the non-liquefied crust layer should be considered in lateral spreading analysis.