Ground surface settlements of sands densified with explosives

Blast densification has long been used to densify loose, saturated sand deposits. Although it is an economically feasible approach to densify large areas, it is not widely used in engineering practice as the design is mostly empirical and some verification tests, such as the cone penetration test, standard penetration test and shear wave velocity test, indicate that the strength and stiffness of the soil do not improve after blasting, even though significant ground surface settlements are measured at the surface. This paper presents ground surface settlements measured at a sanitary landfill located in South Carolina, where 15 zones have been improved with explosives. The results show that blast densification is an effective ground-improvement technique to induce significant ground settlements, increase the soil density and therefore to decrease the liquefaction susceptibility of the blasted layer. The final relative density of the improved sandy layer was > 80% in some areas.