Numerical analysis of vertically loaded rammed aggregate piers and pier groups under dynamic loading

Abstract

Rammed aggregate piers (RAPs) systems have recently received much attention as a cost beneficial technique for ground improvement. Most of the research efforts have focused on the static behavior of piers either in the form of experimental investigations or using numerical techniques. However, their dynamic response has received less attention, despite the fact that there is a tendency to use such systems for machine foundations. Predicting the response of RAP-supported foundations subjected to vertical dynamic loading is then of particular significance in design of structures and machines supported by such a foundation system. To numerically evaluate dynamic response of RAP-supported foundations, a series of 3D finite element models of isolated piers and pier groups were developed taking into account the installation effect and nonlinear behavior of both aggregates and the surrounding soil matrix. The dynamic response of RAP-supported foundations was investigated for different conditions of geometry and soil matrix properties. The paper newly presents the vertical dynamic impedances of isolated piers and pier groups providing new insights into the dynamic applications of aggregate pier systems. The results indicated the capability of rammed aggregate piers technique in reinforcing foundations under dynamic vertical loading.