Numerical Study On Mechanism And Vibration Of High Energy Dynamic Compaction

Dynamic compaction is a ground improvement technique which is particularly effective for loose unsaturated granular soils. The objective is to densify the soils into a state of low void ratio, by compacting the ground. The tamping energy in high energy dynamic compaction is usually greater than 6,000kN.m, which makes it very difficult to conduct an analytical study. However, numerical methods are now available to model the impacting.The objective of this study was to simulate numerically the high energy dynamic compaction using the finite difference method. In the model, the algorithm of large deformation was applied, which made it capable to simulate the badly distorted soil. Curve of crater depth with number of drops was plotted, also the displacement and stress in soil were obtained. Then based on the computational results, the mechanism of high energy dynamic compaction was concluded. And the effects of tamping energy, base area and drop height on ground improvement were investigated.Ground vibration generated during dynamic compaction was studied. The amplitude of ground acceleration reduced rapidly with distance. And the Fourier frequency spectrum of dynamic compaction was obtained. Finally, the effect of isolation trench was analysed in detail.