Metro Sports Facility â€“ A Ground Improvement Case Study-Paper

Paper

Pdf Summary

The Metro Sports Facility in Christchurch is a major post-earthquake recovery project, with a footprint of approximately 22,000 m². Its brownfield site is underlain by soft, compressible silts and loose, liquefiable sands extending to about 20 m, with shallow groundwater and artesian conditions. The site experienced extensive liquefaction and building damage during the 2010–2011 Canterbury earthquakes.<br /><br />Investigations and liquefaction assessments identified risks from both long-term settlement and earthquake-induced ground deformation. Deep piles were considered but judged structurally inefficient and difficult to construct. The selected solution combines deep ground improvement with robust shallow foundations, allowing the building and its floor slabs to be supported by a treated block of ground.<br /><br />The improvement consists of 7,218 vibro-probe stone columns installed on a uniform triangular grid at 2 m spacing across approximately 28,000 m², including a zone extending at least 5 m beyond the building footprint. Columns are generally 10 m deep, with deeper treatment—up to 15 m—beneath heavily loaded or below-ground areas. The design aims to densify clean sands, stiffen and reinforce silty soils, limit liquefaction and settlement, and provide adequate foundation bearing capacity. A gravel drainage layer is also used beneath low-level floors to manage water expelled during earthquakes.<br /><br />Field trials confirmed that the proposed column design could meet performance requirements, although full-depth installation in some areas was challenging. Construction ran from November 2018 to April 2019, with quality assurance testing distributed across the site. Challenges included greater-than-anticipated ground heave and occasional short columns; additional infill columns were installed where required, particularly near the dive well.<br /><br />The works were completed on time and within budget, and testing indicated that the required ground improvement was consistently achieved. The project demonstrates how large-scale stone-column treatment can provide an economical, seismically resilient foundation solution for major infrastructure on difficult liquefiable ground.

Keywords

Christchurch

Metro Sports Facility

post-earthquake recovery

liquefaction mitigation

stone columns

ground improvement

shallow foundations

Canterbury earthquakes

foundation design

seismic resilience