Restoring the city’s Art Gallery with ‘gold-standard’ engineering was a must.
Working with Uretek Ground Engineering (now Mainmark), Harrison Grierson provided structural engineering and building services advice during the tender and remedial work process. We inspected the existing structure and advised on the potential impact of the re-levelling process on the building, and we assisted in developing a suitable lifting and monitoring strategy to relieve the stresses that had built up in the basement slabs. We also advised on the remedial works required for the re-levelling.
The two-stage re-levelling process was relatively new to Aotearoa New Zealand. A specialist team first strengthened the ground with jet grout columns, followed by computer-controlled grout injection that raised the gallery by up to 182mm. The re-levelling was monitored in real time which allowed us to direct the lifting to reduce stress and see almost instant results.
A particular challenge was keeping the existing services at their current level while the gallery was lifted by varying amounts up to 180mm. This required the careful cutting of slots into the reinforced concrete walls and the reinstatement of any lost strength through the introduction of steel frames.
The Christchurch Art Gallery was returned to an eager and enthusiastic public in December 2015, with much-improved levels of quality and stability.