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Ground Improvement Programme

The Canterbury Earthquake Sequence of 2010-2011 included four significant earthquakes that triggered widespread liquefaction and land damage varying in severity throughout the region.

Liquefaction occurs when soil below the groundwater level temporarily loses strength when shaken. This can cause the soil to liquefy, resulting in water, fine sand and silt ejecting to the surface. This places huge stress on buildings on top of liquefied ground.

The Ground Improvement Programme is an EQC Toka Tū Ake (now Natural Hazards Commission Toka Tū Ake) led research programme which informs more affordable and practical ways of making residential land less vulnerable to liquefaction. The world-leading collaborative research was undertaken as part of our role of facilitating research and education that increases New Zealand’s natural disaster resilience. Co-ordinated by Tonkin + Taylor for us, the programme had contributions from many organisations and leading experts in liquefaction from New Zealand and overseas, including:

  • University of Canterbury
  • Ministry of Business, Innovation and Employment
  • Housing New Zealand
  • New Zealand Transport Agency
  • University of Texas at Austin, (USA)
  • Oregon State University (Corvallis, USA)
  • Brigham Young University (Provo, Utah, USA)
  • US National Science Foundation
  • US Network for Earthquake Engineering Simulation.

The Ground Improvement Programme has identified, developed and trialled affordable and practical shallow ground improvement methods which can be used to strengthen residential land. This research is useful to property owners and developers, engineers and builders, private insurers, local authorities and central government agencies. The findings of the research can be applied throughout New Zealand and globally.

You can also watch a video on key findings from the Ground Improvement Programme: 

More about the Ground Improvement Programme

The Ground Improvement Programme, which took place over two years, was divided into two main work streams:

1. The Ground Improvement Trials – ‘the Science Trials’
2. The Ground Improvement Pilot Project – ‘the Pilot’.

The Science Trials included simulated earthquake testing of various ground improvement methods in the residential red zone. Using results from the Science Trials, Ministry of Business, Innovation and Employment updated its 2012 guidance document Repairing and rebuilding houses affected by the Canterbury earthquakes(external link), in April 2015.

The Pilot involved the ‘full scale’ construction of various shallow ground improvement solutions on residential properties.

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