The Cone Penetration Test (CPT)

The Cone Penetration Test (CPT) is a reliable and cost-effective in situ testing method used to determine the geotechnical engineering properties of soils and delineating soil stratigraphy. The test method consists of pushing an instrumented cone tip first into the ground at a controlled rate (usually 2 centimeters/second). The resolution of the CPT in delineating stratigraphic layers is related to the size of the cone tip, with typical cone tips having a cross-sectional area of either 10 or 15 cm². Most modern electronic CPT cones now also employ a pressure transducer with a filter to gather pore water pressure data. The filter is usually located on the cone tip (the so-called U1 position), immediately behind the cone tip (the most common U2 position). Pore water pressure data aids determining stratigraphy and is primarily used to correct tip friction values for those effects. CPT testing which also gathers this piezometer data is called CPTU testing.  CPT and CPTU testing equipment generally advances the cone using Direct Push hydraulic rams using screwed-in anchors as a counter-force. APIC has teamed up with Geoprobe® Systems and Geotech AB of Sweden to operator the CPTU Nova cone cordless data transmission system: a constant stream of data is sent to the surface through the sounding rods.

CPT Features

  • Fast, continuous, real-time profiling of soil subsurface statigraphy
  • Use in both saturated and unsaturated conditions
  • Built to push with APICs Geoprobe® 6600 machine
  • Collects tip pressure, sleeve friction, and pore pressure
  • Parameters are displayed and stored on the Fieldlaptop for future analysis

 CPT Specs (PDF)