Dynamic compaction of saturated sands and silty sands: theory

Dynamic compaction (DC) with pre-installed wick drains is an emerging soil improvement technique for densification and liquefaction mitigation of saturated low-permeability loose sands containing non-plastic silts. The compaction process induces excess pore pressures, possible soil liquefaction, and concurrent densification. Wick drains relieve pore pressures and enhance densification. This paper presents a theoretical model for spatial distribution of the energy dissipated in the soil during dynamic compaction, a pore pressure model based on energy principles to estimate the spatial distribution of pore pressures induced during dynamic compaction, and a coupled consolidation model for pore pressure dissipation and soil densification. It also presents a numerical scheme to implement the theoretical models to simulate dynamic compaction at a site and obtain post-improvement soil densities or penetration resistances. A sample set of simulation results are presented. While this paper is limited to the theoretical development of the models, a second companion paper presents the results from this numerical model applied to a few case histories, and a third companion paper presents a methodology for application of the results for liquefaction mitigation design using DC in silty soils supplemented with wick drains.