Dynamic Compaction

Dynamic compaction uses the energy from a falling weight to improve granular soils and fills.

Common Uses

• Increase bearing capacity
• Decrease settlement
• Mitigate liquefaction
• Reduce sinkhole potential

Technical Details

Dynamic compaction is a ground improvement technique that densifies soils and fill materials by using a drop weight. The drop weight, typically steel, is lifted by a crane and repeatedly dropped onto the ground surface. Vibrations transmitted below the surface improve soils at depth. The drop locations are typically located on a grid pattern, the spacing of which is determined by the subsurface conditions and foundation loading and geometry.

Treated granular soils and fills have increased density, friction angle, and stiffness. In shallow karst geologies, dynamic compaction has been used to collapse voids prior to construction to reduce sinkhole potential. It has also been used to compact construction debris and urban fill as well as sanitary landfills prior to construction of parking lots, roadways, and embankments. The removal of compressible, contaminated fills can sometimes be avoided.