Christchurch sits on a complex alluvial sequence of gravels, sands, and silts overlying the Riccarton Gravel aquifer, a legacy of the Waimakariri River's braided past. The 2010-2011 Canterbury earthquake sequence permanently altered how engineers view the near-surface sediments here. Soft, liquefiable layers between 2 and 10 metres depth are now a primary concern for any structure. CPT (Cone Penetration Testing) cuts through the uncertainty. A 200 kN penetrometer records tip resistance, sleeve friction, and dynamic pore pressure every 10 millimetres, producing a continuous stratigraphic log without sample disturbance. This data feeds directly into liquefaction triggering analyses—specifically the Boulanger & Idriss (2014) CPT-based method—and settlement estimates using Zhang et al. (2002). For deep foundations on the Port Hills fringe, the cone refusal depth on the weathered basalt defines pile termination levels. We run the rig on residential TC3 land, commercial rebuilds in Addington, and infrastructure corridors where MASW Vs profiles complement the CPT for site class determination per NZS 1170.5.
A single CPT sounding replaces three SPT boreholes for liquefaction profiling, delivering a continuous digital log with no sample disturbance.
