Christchurch ground improvement trials

Introduction

If you are a geotechnical engineer you may be interested in the results of ground improvement trials in Canterbury. These were to find ways to strengthen land prone to liquefaction.

Repairing and rebuilding houses affected by the Canterbury earthquakes supplementary guidance.

MBIE will use the trial results to develop technical guidance to repair and reconstruct foundations in Canterbury’s TC3 areas.

The 4 options trialled were:

1. cement-stabilised two-metre-thick raft over the building platform – formed by excavation, mixing and recompaction or in-place mixing
2. deep soil mixing columns – constructed in a grid pattern to provide 15-20 per cent ground coverage beneath the building
3. perimeter curtain wall – to form a protected cell around the building
4. densification by excavation and recompaction or by dynamic compaction – dropping weights repeatedly in order to make the ground beneath the building denser.