Influence of the head fixity adjustment of existing piles on the lateral load response of new piles

The reuse of existing piles is a significant path to achieving low-carbon, resilient, and sustainable urban construction. However, some key issues in this area remain unresolved, especially with regard to the lateral interaction of new and existing piles. This study used centrifuge tests and numerical simulations to investigate the influence of the head fixity adjustment of existing piles on the lateral load response of new piles. The lateral load responses of new piles were compared for four conditions of the heads of existing piles, and the contributions of existing piles to new piles were examined. An extensive parametric study was conducted to quantify the relative contributions of the existing pile head fixity to the lateral load response of new piles for different variables, including new-existing pile spacings, displacements of new piles, restraints of heads of new piles, and soil properties. Finally, a practical method was developed for the design of laterally loaded new piles that considers the head fixity of existing piles. The results of this study provide a feasible way to enhance the contributions of existing piles to the lateral load responses of new piles through the adjustment of the fixities of existing pile heads.