Dynamic compaction is an impact ground improvement technique that improves granular soils through the application of surface energy loads by means of a tamper. Subsurface vibrations created by this action collapse the soil skeleton within the zone of influence of the tamper, resulting in increased density, friction angle and stiffness.
Deep Dynamic Compaction
Deep Dynamic Compaction (DDC) typically utilizes a crane-hoisted steel tamper (drop weight) lifted to a pre-determined height and dropped on the ground surface in a regular grid pattern across the treatment area, creating a characteristic “egg carton” pattern of surface craters. Two or more passes are typical, with the initial grid offset to ensure uniform treatment. Drop height and tamper tonnage are determined by the depth of soil to be treated. A final “ironing pass” densifies the upper few feet of soil loosened by the formation of the craters.
- Rapid, economic alternative to excavation and replacement
- Can eliminate the need to remove compressible or contaminated fills
- Site improvement for future construction
- Void collapse in shallow karst conditions to reduce sinkhole potential
- Landfill compaction for parking lot and roadway construction
Rapid Impact Compaction
Rapid Impact Compaction (RIC) is similar in methodology and intent to Deep Dynamic Compaction but is limited to treatment of shallow, relatively granular soils located above the groundwater table. Purpose-built equipment incorporates a hydraulic hammer that strikes an impact plate on the ground surface. Multiple impacts across a regular grid pattern achieve the desired improvement.