Evaluating the effective depth of rolling dynamic compaction with a three-sided compactor

Rolling dynamic compaction (RDC) is a ground improvement technique that involves towing a non-circular module forward with a tractor. It is widely used in the construction industry due to its high mobility and relatively small size. However, there remains a paucity of engineering models to predict soil behaviour in different conditions. This paper presents the investigation of sand particle movement during RDC with a three-sided compactor using a 1:10 scale model in the laboratory. Settlements at different depths and cone tip resistance were obtained to determine the increase in soil density, and a high-speed camera was used to capture images so that the displacements of the sand particles could be determined using the particle image velocimetry. The results show limited compaction near the surface where soil is moved laterally due to a combination of bearing failure and the applied frictional stresses, but significant increases in density for initially loose sand to depths of greater than 4 m at full scale. Tests on sand with initial relative density of 0.6 showed only small density increases.