Dynamic response and densification mechanism of dynamic compaction for silt soil through a large scale field test at Daxing Airport

Dynamic compaction (DC) is widely used to improve ground with various soil types and environmental conditions. In this study, large-scale field tests at Daxing Airport were proposed to investigate the dynamic characteristics of soil induced by DC under three energy levels (1000 kN m, 1500 kN m, and 2000 kN m). Standard penetration test (SPT), pressuremeter test (PMT), and vibration (velocity and acceleration) tests were conducted to measure the variation in soil properties. The results show that, in the tamping process, the vibration amplitudes were stabilized after a certain number of blows, which has a similar variation trend as the crater settlements. A critical vibration acceleration of 5g was obtained through the correlation between the vibration and soil properties, indicating that when the vibration acceleration exceeded 5g, the soil properties changed significantly. These findings provide a reference for the development of real-time diagnosis of compaction state based on the vibration tests.