Dynamic Compaction: Building in the Shaky Isles

With 15,000 earthquakes per year, New Zealand's “Shaky Isles' nickname is well-deserved. This has a direct impact on the way we need to approach the erection of our buildings.

Building foundations in seismically active areas often require ground improvement to be performed prior to laying down foundations. This is done in order to prevent liquefaction and building settlement in a strong earthquake.

Dynamic Compaction is a ground improvement technique used to densify the soil beneath the foundations and floor to a depth of about 4 metres. The soil is ‘Dynamically Compacted’ by dropping a weight or hammer, typically about 12 tons, measuring 1.5m metres in diameter. This weight is dropped from a specifically modified crawler crane at a height of up to 30m metres. This is done multiple times in the one position and then repeated in sequence in a grid pattern, typically at 3.0m centres.

Dynamic Compaction is not a new technique but is a specialised method of ground improvement suited to particular soil types and has proved to be the most economic solution on many projects around New Zealand including the Te Papa Museum in Wellington.

Lattey Group provides Dynamic Compaction expertise and services and have used it over several building sites in New Zealand. Contact us to get more information