Rapid impact compaction densifies shallow, granular soils using a hydraulic hammer, which repeatedly strikes an impact plate on the ground surface.

Rapid impact compaction technique illustration

Common uses

Increase bearing capacity
Decrease settlement

Process

Energy is transferred to the underlying loose granular soils rearranging the particles into a denser formation. The impact locations are typically on a grid pattern, with spacing determined by the subsurface conditions and foundation loading and geometry.

Advantages

Treated granular soils and fills have increased density, friction angle, and stiffness
Low cost treatment to soils 3-4m in depth
Enables shallow foundations to be used opposed to deeper more expensive foundation solutions

Quality assurance

The energy and deflection of the soil are monitored and recorded at each location, which allows the geotechnical engineer to determine when effective treatment is complete. It also enables the engineer to identify weak zones (red dots) or debris zones throughout the pad so that any remedial actions that may be required can be minimized, resulting in cost savings.