A New Index for Estimating the Improved Depth of Dynamic Compaction

Improved depth is of fundamental importance for earth-filled foundations with dynamic compaction (DC) and is closely relevant to the mechanical characteristics of earth fillers under impact load. This study carried out numerical DC tests on fine-grained soil to estimate the improved depth more easily and accurately. The filler's multiscale responses, including crater depth and porosity, were evaluated. Results showed that a heavier tamper weight with a lower drop distance was relatively more efficient in densifying soil fillers, although the tamping energy (MH1.0) and tamping momentum (MH0.5) were the same; however, contrary results were observed under the same value of MH0.2. In addition, three different combinations of M and H led to similar soil responses under the same value of MH0.3, which is thus recommended as the new index to estimate the improved depth and densification efficiency of DC. A mechanistic analysis found that M contributes more than H to compact soil fillers, which can be quantified by contribution ratio alpha. Moreover, large-scale field DC tests confirmed the findings.