Rapid impact compactor is a process where loose subsurface soils are improved using an excavator-mounted 10 ton hydraulic hammer. The hammer is rapidly raised and lowered onto a 1m diameter plate, which densifies the soil, in-place, without the need for undercut and replace. The average compaction point is hit 40-90 per minute.
Rapid impact compactor is a high-frequency, controlled energy, soil compaction technique used to densify surface layers of soils (to a depth of 5 to 7 meters in most cases) with minimum impact on the immediate worksite environment. Rapid impact compactor is widely used to densify loose granular soils (sand or gravel) as well as loam fill and industrial brownfield sites for surface compaction, foundations and floor slab support, liquefaction mitigation and waste stabilisation.
The principle of the technique which is similar to other compaction / densification techniques is a transmission of energy into a compressible / loose soil layer in order to improve its geotechnical properties.
A compaction plate is placed on the ground to be treated. Rapid impact compactor generally weighing less than 10 to 15 tonnes, is fitted to an excavator and used to transmit compaction energy to the soil via repeated impact. Without specific site precautions, a safe working distance to sensitive structures can usually be defined on the order of 8 to 10 m, as a distance of 5 to 6 m can usually be adopted for classical structures. At that distance, noise levels are lower than 90 dBA.
Advantages
Treated granular soils and fills have increased density, friction angle, and stiffness
Low cost treatment to soils 3-5m in depth
Quick start as no excavation, adding water or dewatering is required
Enables shallow foundations to be used opposed to deeper more expensive foundation solutions
Construction can start immediately after work is completed as it leaves a clean site free from debris
Rapid impact compactor is a technique allied to Dynamic Compaction that can be used to increase the bearing capacity of soils through controlled Impact. The treatment is effective in the top layers of soil, typically up to 6m depth, though improvements up to a depth of 9m have been seen in some conditions.
Drop weights of 10 tonnes are used on our HC150 Rapid impact compactor machines respectively and are dropped from heights of 1.2m – 1.5m onto a special foot assembly at 40 – 90 times per minute. The foot remains in contact with the ground at all times.
