Experimental investigation into the effects of tamper weight and drop distance on dynamic soil compaction

Estimating the densification efficiency of soil fillers is the main topic in dynamic compaction (DC). However, existing methods fail to assess the different contributions between tamper weight (M) and drop distance (H). In this study, a DC laboratory setup was developed to allow such different contributions to be analyzed. A series of DC tests were conducted on a red clay from China with six combinations of tamper weight and drop distance and twenty multiple blows in each combination. The soil responses including crater depth, plastic deformation, impact stress, and inside stress spectrum were recorded. It was observed that with the same tamping energy and momentum, a heavier tamper with a lower drop distance enabled a deeper crater depth and larger plastic deformation. Further examination showed that a heavier tamper caused impact stress with a longer period, increasing the stress wavelength and propagation ability. Therefore, a larger soil body was involved in the compaction process. Additionally, with the same value of MH0.3, different combinations of tamper weight and drop distance shared similar impact stress and soil responses, which is recommended as the new index to estimate the DC densification efficiency for the studied red clay.