Study on Dynamic Compaction Reinforcement Effect and Dynamic Stress Response Patterns of High-Fill Gravel Soil Foundation

To investigate the effects of different compaction energies on the reinforcement effect and soil dynamic stress of high-fill crushed stone foundations, this paper takes the foundation of a bullet train de-pot in Chongqing as the research object. The field dynamic compaction tests are conducted to analyze the compaction settlement and dynamic penetration blow counts under various compaction energies, and the influence of compaction energy on foundation reinforcement is discussed. The FLAC3D numerical simulations are performed to explore the deformation of internal soil mass and variation patterns of soil dynamic stress under different compaction energies, so as to reveal the transmission patterns of dynamic compaction energy. The results show that the reinforcement effect of dynamic compaction on soil is mainly achieved before the optimal number of tamps. The depth range of 2 to 3 meters is identified as the high reinforced zone. As the compaction energy increases, the growth rates of peak dynamic soil stress and dynamic penetration blow counts gradually decline. The peak soil dynamic stress in shallow soil attenuates lower under high-energy than that under low energy. After multiple compaction, the shallow soil becomes compacted and stable, and the impact energy transfers from shallow to deep layers. The closer to the foundation surface, the smaller the variation amplitude of soil dynamic stress.