Grout injections Improve Earthquake Resilience For Christchurch Apartment Building

Since the 2010 and 2011 earthquake events, widespread liquefaction has affected building foundations across Christchurch and the wider Canterbury region. Introduced in 2017, New Zealand’s Building (Earthquake-prone Buildings) Amendment Act 2016 categorises seismic risk of a building under the New Building Standard (NBS). By working towards achieving 100% NBS, property owners can ensure the ongoing resilience of their buildings and future safety of occupants during seismic events. KCRB Director Bruce McDonald sought to achieve 100% NBS, and engaged geotechnical and structural engineers to analyse both the building and underlying ground conditions. The analysis identified there was adequate ground stability bearing capacity to proceed with re-levelling the building, which had suffered differential settlement due to the earthquakes. It was also decided to widen and strengthen the building’s foundations. Mainmark was contracted to undertake ground remediation and re-levelling works, and was selected due to the organisation’s experience and expertise in delivering ground improvement and liquefaction mitigation solutions to structures of all sizes, including the 33,000 tonne Christchurch Art Gallery.

Mainmark was required to strengthen the ground beneath the wider structural foundations and return the eight-storey building to level, achieving overall tolerances of +/- 10mm across the entire footprint. The ground remediation and re-levelling works were a crucial step toward achieving 100% NBS. The building’s lift shaft also needed to be leak-sealed to prevent water ingress.