An analytical approach to pile-to-pile interaction for end-bearing piles

This study introduces an analytical approach to treat pile-to-pile interaction for axially loaded, end-bearing piles. Building upon an available Tajimi-type soil model and an application of Graf’s addition theorem, the proposed solution simultaneously considers both the source and the receiver piles. In particular, results are shown for interaction factors, and pile and soil displacements for the case of two piles, which can additionally be subjected simultaneously to different loads. The predictions are compared with results from available methods in the literature, and additional finite-element analyses. The proposed interaction factors are in excellent agreement with rigorous models. The displacement of a single pile without the receiver is straightforward. At the location of the receiver pile, the displacement is calculated as the average displacement around the perimeter of the pile at its head. This calculation accounts for the dependence of the displacement at the soil–pile interface on a relative angle, as determined by the application of Graf’s addition theorem. The factors for piles in vertically inhomogeneous soils are also shown, by using an equivalent stiffness of a fictitious homogeneous soil layer from the literature. This study lays the groundwork for extensions to irregular pile groups subjected to multi-directional inertial and kinematic loads in inhomogeneous soils.