Numerical investigation of the performance of the 3-sided impact roller

Abstract

Rolling dynamic compaction (RDC) is a soil improvement technique, which involves towing heavy (6–15 t), non-circular (3-, 4-, and 5-sided) modules behind a tractor to achieve soil compaction. Both potential and kinetic energies are imparted to the underlying soil as the modules fall and impact the ground. This paper presents a combined, three-dimensional finite element method (FEM)-discrete element method (DEM) model to investigate the behaviour of the 1:13 scale, 3-sided roller. Numerical results are compared against results from a field study using the corresponding full-size, 3-sided roller in two aspects namely, ground settlements and induced peak pressures. It is demonstrated that the numerical results are in very good agreement with the field observations. This paper examines the influence of the twin modules of the 3-sided roller with respect to ground improvement and the results suggest that the soil beneath a single module is improved solely by the module above it. Therefore, the current practice of using the total weight of the 3-sided roller to predict the energy imparted to the ground and the depth of influence should be avoided. The validated numerical model is also used to predict the energy delivered to the soil and the depth of influence of the roller. The energy imparted to the ground is approximately 22.5 ± 3 kJ per impact with 95% confidence, and the depth of influence is approximately 1.5 m for each of the twin modules of the 13-t, 3-sided roller operating at 11 km/h on granular soils investigated in this study.