This paper recognizes that soil layering may have a profound effect on the settlement of pile groups and that pile-to-pile interaction induces not only additional settlement at the head of each pile but also additional stresses along its shaft. A general analytical formulation is developed, based on the Winkler model of soil reaction, for determining the vertical interaction factors between two piles embedded in multilayered soil. It is shown that such interaction factors depend not only on the displacement field arising from the settlement of a loaded ('source') pile but also on the interplay between the adjacent ('receiver') pile and the soil subjected to this displacement field. Such interplay, which has not been considered (at least explicitly) in currently available simple methods, is quantified here through an analytically determined factor ξ, which lies between 0 and 1. The paper also develops closed-form expressions for pile stiffness and interaction factors in a two-layer stratum, and highlights crucial aspects of the problem.
- Numerical modelling and analysis
- Soil/structure interaction; stiffness