What is Dynamic Compaction?

Dynamic Compaction consists of using a heavy tamper that is repeatedly raised and dropped from varying heights to impact the ground. The mass of the tampers generally ranges from 10 to 30 Tons, and drop heights range from 40 to 100 feet. The energy is typically applied in phases on a grid pattern over the entire area using single or multiple passes. Following each pass, the craters are either levelled with a dozer of filled with granular fill material before the next pass of energy is applied.

The degree of soil improvement is a function of the impact energy applied, including the mass of the tamper, the drop height, the grid spacing, and the number of drops at each grid point location. Light tampers and smaller drop heights result in the depth of improvement on the order of 10 to 15 feet. Heavier tampers and greater drop heights result in the improvements on the order 20 to 30 feet.

The soil improvement by Dynamic Compaction can be verified by post improvement CPTs or SPTs. In building rubble or construction debris, where conventional CPT and SPT

are not feasible, surface wave measurements (SASW or MASW) or surcharge load tests can be used as alternative quality control methods.

Dynamic Compaction is considered as the lowest cost ground improvement method to effective treat large areas, such as airport, road or dam embankment base, warehouse building, and large residential track development. Without construction material consumption, Dynamic Compaction treatment has the lowest carbon footprint compared to all other ground improvement technologies.

Malcolm Drilling has the largest fleet of duty cycle cranes in the ground improvement industry, specially made for Dynamic Compaction operations with temper weights of up to 30 tons and drop heights exceeding 90 feet, automated triggering system and safety protections. Malcolm Drilling is capable of providing design, supervision, equipment, labor, safety inspections, survey, vibration measurements, gradings, and materials required to achieve the specified results.

Dynamic Compaction has been successfully used to improve weak ground deposits including:

  • Loose sands and silts to mitigate liquefaction potential
  • Loose naturally alluvia granular deposits or hydraulic fills
  • Landfill both recent and old
  • Building rubble and construction debris
  • Strip mine spoil
  • Collapsible soils including loess
  • Partially saturated clay deposits above water table
  • Formations where large voids are present such as karst or sinkholes closed to grade
  • Special waste