The recent Canterbury earthquake events caused extensive liquefaction in this area. With layers of sand and silts a total of up to 30m deep in places, over the underlying gravels, which have a high tendency to liquefy during earthquake shaking.
The original building has been built with these site conditions in mind and well tied together so that when the settlements did occur the building moved as one, rather than breaking apart.
Due to the liquefaction induced settlements, the building now leans to the north and has an overall settlement over the full length of the building of 300mm.
To repair and re-level the building, new steel screw piles will be installed around the perimeter of the building and at key internal locations. The piles will extend to, and bear firmly on, the gravels which enable this heavy building to be re-levelled and greatly reduces the likelihood of settlement from future earthquake events.
The existing ground floor slab and some of the foundations will be removed to allow the piles to be installed. New foundations will be provided with sleeves and jacks at each of the pile locations and well tied into the existing structure.
The building will be lifted in an eight zone synchronous lift system with each zone lifted by approximately 25mm per lift starting from the side of the building that has settled the most.
Once the building has been returned to its pre-earthquake level the lifting jacks will be locked off and tied into the foundations. New suspended ground floors will be provided over an in-ground reservoir thus allowing potential liquefaction material in future earthquakes to dissipate rather than damage the slab.
The re-levelled and repaired building will be just as strong as and more resilient than it was prior to the recent earthquakes.
- Chris Hurst, Structex Limited
Unit 8, 48 Fitzgerald Avenue is two storey multi use
building comprising of 446 m2 of warehouse, with dual access roller doors
providing a rare drive through facility. The ground and upstairs office area
complete with boardroom and north facing balcony occupy 314 m2 of the building.
Due to the necessary repairs that will be undertaken
following the Christchurch earthquakes there is an ability to adapt this
building to suit and the possibility for a split tenancy with separate entrances.
The refurbishment will consist of strengthening works to the
current foundations which will ensure the building is a minimum 75% of the
current building code.
