Numerical Modeling of the RAP Construction Process and Its Effects on RAP Behavior

Abstract

Although rammed aggregate piers (RAPs) have attracted much attention as a cost-beneficial ground improvement technique, their construction process and the other affecting parameters on the behavior of these geotechnical structures during the construction and loading phases have not been properly investigated and only some predictions for downward and radial expansion resulting from the construction process have been proposed to be used in numerical simulations. The goal of this paper is to numerically simulate the RAP construction process to investigate the effect of construction sequences on RAP behavior. Keeping this aim in mind, a hybrid distinct element–finite difference algorithm is developed to simulate the placing and ramming of the RAP’s clean crushed stone layers in detail. Introducing several numerical models, a parametric study was then conducted to compare the behavior of RAPs during the construction process for different pier geometries and soil properties. The results of this research not only help to understand the RAP behavior during the ramming process but can also be used as a guide for predicting the amount of downward and lateral expansion of RAPs after the ramming process.