Investigation of Compaction Parameters for Red Clay Reinforcement Using the Punching-Compaction Dynamic Compaction Technique

Red clay, characterized by high moisture content and a high plasticity index, is widely distributed across the Yunnan Plateau and commonly serves as a predominant foundation soil for infrastructure development. The Punching-compaction dynamic compaction (PCDC) technique, notable for its deep penetration capacity and for forming granular column-composite foundations through gravel-clay mixtures in compaction holes, is widely adopted to reinforce underconsolidated red clay sites. However, its dynamic behavior remains insufficiently studied. Laboratory model tests were conducted to evaluate the effects of filler ratios, compaction energy (8000 ~ 10000 kN·m), hammer angles, and blow counts on cumulative penetration depth, soil acceleration, and peak pressure. Results revealed that cumulative penetration depth correlates logarithmically with blow counts, with 10000 kN·m achieving 10% greater penetration than lower energy levels. Higher energy induced stronger vertical/horizontal accelerations, while flat-bottom hammers combined with high energy optimized efficiency. Gravel-soil mixtures enhance column density during densification, with increased gravel content improving soil compactness.