A field study of dynamic compaction in the construction of a stone-filled embankment

Road embankments in the mountainous terrains are typically constructed using locally available stones through dynamic compaction (DC) because of the relatively low cost; however, the filling quality of large stones is difficult to control with limited research and field performance data available. This article presents the results of a field study for estimating the construction parameters including effective improvement depth, number of tampering points, and lateral influence distance for a DC of a stone-filled embankment. The pilot field-testing programconsisted of roller compaction and DC. The field test data included tamping settlement and surface uplift after each hammer drop. Static and dynamic soil pressures were measured, and the former was used to correlate with compacted fill density. The field data show a strong correlation between the static soil pressure increment and compacted fill density. Based on this correlation, it was found that (1) in order for each DC point to achieve the target compacted fill density, it was necessary for tampering to be done a total of eight times; (2) the effective improvement depth was approximately 5 m; and (3) the lateral influence distance was approximately 2.5 m and, hence, a horizonal interval of 5 m was determined for the layout of tampering points in the field construction. The good in-service performance of the completed embankment and paved road suggests that the pilot field-testing program was a success in determining the construction parameters.