CCNZ / HIREPOOL CONSTRUCTION EXCELLENCE AWARDS 2015
Groundfix flexes technical muscle in spectacular slab repair When the basement car-park slab in central Auckland’s Vodafone building started showing signs of structural distress, more than a few alarm bells went off. However, thanks to the skill of Groundfix things were remedied quickly and effectively.
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CONSTRUCTION EXCELLENCE AWARDS 2015
HIGHLY COMMENDED CATEGORY 1
PROJECT: Basement Carpark Remedial Works, Auckland CONTRACTOR: Groundfix
12 Civil Contractors NZ in association with Contractor magazine
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etween August and October 2014 specialist ground engineering firm Groundfix went about the task of installing 68 tension piles to hold down the enormous basement slab in Vodafone’s building. The piles (each with a capacity of 500 kilonewtons ultimate limit state) were driven between eight and 10 metres deep. The job was complicated by the fact the basement had to remain a functioning car park throughout the works. At no point was the number of car parks allowed to drop below 75 percent of existing capacity. Other stringent client requirements revolved around noise levels, dust and deliveries. From an engineering perspective, a major issue faced by the project team was the presence of ground water. In fact, the water table was two metres above the top of the basement slab. To get around this, a bespoke dewatering system was devised – made up of well points, an extraction manifold, a pumping station and exhaust water pipework. Importantly, the well points were constructed in ‘dead areas’ created by internal building support columns, stairwells and ramps to help minimise the impact on car parking spaces. Groundfix director Justin Wilson points out that if the dewatering process had failed the entire project would have
