The biggest mistake we see in Christchurch is a structural engineer specifying piles without a site-specific geotechnical model behind them. It looks fine on paper until the rig hits an uncompacted sand layer at four metres and the whole piling schedule unravels. The Canterbury earthquakes rewrote the rulebook on what lies beneath this city, and pile foundation design here is not a copy-paste exercise from Auckland or Wellington. We start every pile design with a forensic look at the ground profile: cone penetration test data, shear wave velocities from MASW surveys, and the liquefaction susceptibility mapped in the Canterbury Geotechnical Database. That data drives the axial and lateral capacity calculations, not the other way around. For deep soft spots near the Avon River corridor, we often integrate stone columns as ground improvement ahead of piling, creating a composite system that reduces differential settlement under seismic load.
Christchurch taught the engineering world that liquefaction isn't just a yes/no trigger. It's a spectrum that pile design must quantify, layer by layer.
