Enhancing Ground Improvement of Dredging Landfill in South Korea’s Western Coastal Region: Insights into Dynamic Compaction Characteristics

In this study, a dynamic compaction soil box test is performed to analyze the effect of changes in energy according to the pounder tamping number of dynamic compactions on ground improvement. As reproducing the test on the in situ ground is challenging, a 3.0 m × 2.4 m × 1.0 m soil box is used. The number of pounder tamping repetitions of the dynamic compaction is tested in up to six steps, five times at each tamping point. The change in excess pore water pressure appears to begin to converge at step three (Nd = 15) of pounder tamping. The change in pore water pressure with respect to the number of tamping using the finite element analysis program AFIMEX GT-2D is found to have an effect at up to 4.0 m vertically and 3.0 m horizontally, similar to the results of the soil box test. The static cone penetration resistance at each pounder tamping stage increases by 1.3, 1.7, and 1.1 times at step two (Nd = 10), step three (Nd = 15), and step six (Nd = 30) of tamping, respectively. The depth of improvement coefficient (α) ranges from 0.26 to 0.52, with an average of 0.39. The improvement effect of the in situ improved ground can be inferred in advance from the correlation between the number of pounder tamping repetitions, ΔN, and the internal friction angle. Once the ground improvement range is determined, it can be used to determine the in situ dynamic compaction energy (weight of pounder, tamping of height) using the given improvement depth coefficient (α).

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