Experimental study on dynamic compaction to improve saturated soft clay covered with hydraulic fill sand

According to geological conditions and engineering loads of different zones of a harbor project, a series of dynamic compaction tests with different techniques were performed. Ground deformation around ramming points, horizontal displacement in soil mass and pore water pressures were monitored; and compaction effectiveness was tested. Research results show that it is feasible to treat the saturated soft soil covered with hydraulic fill sand by dynamic consolidation method, of which effective improvement depth is six to seven meters; and the depth of hydraulic fill sand influences remarkably on effective ramming power and function of gravel-soil cushion. Vertical drainage measure may not be taken because of the presence of hydraulic fill sand layer and silty sand layer if improved depth to need is shallow. By analyzing the measuring data, the optimal parameters and construction techniques are obtained; and the depth of hydraulic fill sand shall be taken into account when construction techniques is chosen.