Cyclic lateral response of piles in dry sand: Finite element modeling and validation

The response of a vertical pile embedded in a dry dense sand when subjected to cyclic lateral loading is studied numerically. Three-dimensional finite element analyses with a new constitutive model of cyclic behavior of sand reproduce published centrifuge tests results. Three types of cyclic loading, two asymmetric and one symmetric are applied. Performance measure parameters (the normalized tangent and secant stiffnesses with respect to the first cycle of loading and the relative pile head displacement between two consecutive loading-unloading reversal points) are introduced to evaluate the results of the overall response of the pile–soil system. The results replicate the plastic shakedown response of the pile -soil system during cyclic loading, a response which is attributed to two mechanisms (a) soil densification and (b) “system” densification due to the gradual enlargement of the resisting soil mass to greater depths with cyclic loading. It is shown that the hardening mechanism of “system” densification dominates upon soil densification in cyclic loading. The response of a 1 × 2 pile group under cyclic lateral loading is also numerically investigated, emphasizing the role of cyclic loading on (a) the pile-to-pile interaction, (b) the additional pile distress due to the group effect, and (c) the shadow effect.