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-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 EQC’s role of facilitating research and education that increases New Zealand’s natural disaster resilience. Co-ordinated by Tonkin + Taylor for EQC, 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.

A summary of the results, lessons and outcomes from the Ground Improvement Programme can be found in our newly released report titled:

"Residential Ground Improvement: Findings from trials to manage liquefaction vulnerability" (PDF - 6.5 MG)

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, in April 2015.

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

Questions and answers

You can find a list of questions and answer on Ground Improvement Programme here.

Related information

Related documents:

• Residential Ground Improvement: Findings from trials to manage liquefaction vulnerability report; October 2015
• Report on Ground Improvement Costs for Cleared Sites in the Canterbury Area; June 2015
• Ground Improvement Programme. Horizontal Soil Mixed Beams Proof of Concept Pilot Summary Report; November 2016
• What were the Canterbury Ground Improvement Science Trials? fact sheet; October 2015
• What was the Ground Improvement Pilot Project? fact sheet; October 2015
• What is a cone penetration test (CPT)? fact sheet; October 2015
• What is crosshole geophysical testing? fact sheet; October 2015
• What is T-Rex shake testing? fact sheet; October 2015
• What is blast-induced liquefaction testing? fact sheet; October 2015
• What are stone columns? fact sheet; October 2015
• What are Rammed Aggregate Piers? fact sheet; October 2015
• What are driven timber poles? fact sheet; October 2015
• What are reinforced soil-cement rafts? fact sheet; October 2015
• What are reinforced gravel rafts? fact sheet; October 2015
• What are Horizontal Soil Mixed (HSM) beams? fact sheet; October 2015
• What are standard specifications? fact sheet; October 2015
• What is a resource consent and why do I need one for ground improvement? fact sheet; Oct 2015
• What is a building consent and why do I need one for ground improvement?  fact sheet; Oct 2015
• Ground Improvement Trials Brochure; August 2014
• Ground Improvement Programme brochure; October 2015
• Improving Liquefaction Vulnerable Land infographic; 2013

 

 

Page last updated: 21 Nov 2016

Translated material: