Abstract
Dynamic compaction has been carried out on reclaimed soft ground in Chiba prefecture, Japan to reduce liquefaction potential and ground settlement due to consolidation. The ground was reclaimed with up to 12m of inhomogeneous fine-grained soil 30 years ago. The dynamic compaction process, carried out prior to construction of a factory building, entailed lifting a drop weight of 250kN with a crane and dropping it repeatedly on the ground from a height of 25m. Impact points were spaced at intervals of 5m. Geotechnical site investigations were performed before and after compaction to confirm its efficiency. These investigations reveal that (1) an increase in SPT N-value is observed in sandy soil, (2) increased consolidation yield stress is observed in clayey soil, and (3) increased Nsw values by the Swedish Weight Sounding test are observed in both sandy and clayey soils. These results demonstrate that dynamic compaction is an effective method of improving both sandy soils and clayey soils.
