Abstract: To overcome the shortcomings of traditional dynamic compaction method, a new technique of intube deep dynamic compaction was proposed. The equipment, reinforcement mechanism and construction procedures of this new method were described. Based on the field test in Fujian, some factors such as filler content and deep dewatering were monitored during reinforcement. The test results show that the accumulation of excess pore water pressure during the tamping process can be effectively avoided by the intube deep dynamic compaction method, and the excess pore water pressure will dissipate completely after 1 day of dynamic consolidation. When the sand grains are added into the soil, the tip resistance and cone side resistance increased exponentially after the reinforcement, and the effective depth of foundation treatment can reach more than 15m in depth. The defects of the long period of dissipation of excess pore pressure and shallow depth of the effective reinforcement in conventional dynamic consolidation method are overcame.

Key words: soft soil foundation; in-tube deep dynamic compaction; dissipation of excess pore pressure; depth of effective reinforcement