Numerical investigation on zone of improvement for dynamic compaction of sandy ground with high groundwater table

This paper presents a numerical study of dynamic compaction (DC) on ground improvement in foundation with a high groundwater table, based on a dynamic fluid-solid coupled finite element method with a cap model. Firstly, an analysis of dry ground was carried out to evaluate the effective improvement range, with the proposal of a normalized formula capturing the improvement effect. Then, the parametric studies include the effect of groundwater table, the permeability coefficient, drop energy, and soil type have been carried out to not only find that the groundwater table has a dominant influence on soil improvement by DC but also clarify densification mechanisms of ground improvement by DC on the soil nearby groundwater table, which is through analyzing the contours of effective mean stress. Finally, a relative enhancement index, R-D, based on a total of 52 calculations is derived to evaluate the depth of improvement below the groundwater table for different scenarios. These relationships provide a valuable reference for the evaluation of ground improvement by DC for a foundation with high groundwater table and the applicability of the proposed procedure is illustrated by comparing its prediction with three cases of DC in the field.