Finite Element Numerical Analysis to Evaluate the Lateral Behavior of Three Pile Group Configurations-Paper

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The study uses three-dimensional finite-element modeling to compare the static lateral behavior of vertical, battered, and mixed pile groups. The models represent prestressed concrete piles in a 4-by-6 arrangement and build on a previously validated model of the battered pile group at the I-10 Twin Span Bridge. Nonlinear concrete and soil behavior, pile–soil interaction, and interface gapping were included. The groups were compared by load–displacement response, row-by-row load sharing, axial reactions, back-calculated p–y curves, and p-multipliers.<br /><br />The battered group was stiffest: its lateral stiffness was 120% greater than that of the vertical group, while the mixed group was 50% greater. At the maximum modeled load, lateral displacement was 76 mm for the battered group, 165 mm for the mixed group, and 280 mm for the vertical group. Load distribution among rows varied by configuration: the vertical group shared load relatively evenly, the battered group relied more on its middle rows, and the mixed group carried more load in its leading and trailing rows.<br /><br />Axial reactions were significant in two rows of the vertical and battered groups, but across all four rows of the mixed group. Back-calculated p-multipliers, which indicate the reduction in soil resistance due to pile-group interaction, were highest for the battered group. In all configurations, exterior piles had higher p-multipliers than interior piles, reflecting weaker group effects at the edges; the authors suggest average multipliers may decline as the number of pile columns increases.<br /><br />Overall, the results indicate that battered piles can substantially improve lateral stiffness, while pile arrangement affects load sharing and group interaction. The conclusions are based on finite-element simulations calibrated from a specific bridge foundation and soil profile.

Keywords

finite-element modeling

pile groups

lateral behavior

battered piles

vertical piles

mixed piles

pile-soil interaction

p-y curves

p-multipliers

bridge foundation