Geotechnical Cone Penetration Testing (CPT) Services

The Cone Penetration Test (CPT) is an in-situ test widely used for geotechnical site investigations thanks to its high production rates, repeatability of measurements, and near-continuous profiling of geotechnical parameters that are key to understanding soil behaviour. A universally trusted soil investigation method, CPT systems can be deployed from the ground surface with a variety of rigs, or over water from barges and platforms.

Legion Drilling provides CPTu tests for geotechnical applications across Australia to examine and record the geotechnical engineering properties of site soils and mine tailings. This testing method provides valuable subsurface information that can be correlated to soil type, soil strength and other properties. It involves a CPTu cone which is pushed into the ground at a standard rate and electronic measurements are recorded at regular intervals. The CPT probe measures cone resistance at the tip and friction in the sleeve during penetration.

In addition to the measurements of sleeve friction and cone tip resistance obtained with electric CPT probes, Legions Piezocone Penetration Testing (CPTu) systems also record pore water pressure and are compatible with seismic modules (SCPTu) to determine compression and shear wave velocity.

If requested, samples can be rapidly collected using direct push technology in adjacent locations. Our Geopoeb cone penetrometer test rigs are also capable of auger, direct push sampling and rotary air drilling for the installation of geotechnical instruments, groundwater monitoring wells, inclinometers and other instruments.

MAJOR BENEFITS OF CPT (CONE PENETRATION TEST)

  • Near-continuous profiling of multiple geotechnical parameters.

  • Rapid data collection (20 mm/s).

  • Real-time visualisation.

  • Compatible with external modules (SCPTu).

  • Built-in inclinometer to identify any deviation from the vertical axis.

  • Universal quality standards and design codes. Repeatable and reliable.

  • Sensitive cones available especially designed for very soft soils and mine tailings.

  • Operable on light track-mounted machines for difficult access locations.

COST-EFFECTIVE ALTERNATIVE TO STANDARD PENETRATION TESTING (SPT)

In general, CPT and CPTu are considerably more accurate and less time consuming than SPT. Furthermore, CPT and CPTu measure multiple geotechnical parameters (not just the N value) and are less expensive than SPT on a per data point basis.

BENEFITS OF GEOPROBE MOUNTED CONE PENETROMETER TEST

  • Access almost any location with compact track-mounted machines. Go where others can’t.

  • High stability to traverse across rough terrain and on steep grades (e.g., dam embankments).

  • Ground pressure of only 0.27 kg/cm2 (which can be further decreased with track mats) enabling access to sites with very soft soils and tailings.

  • Save on costs by using the same rig to: (i) predill through ballast and fill (augers/rotary air); (ii) collect near-continuous, high-integrity cores as well as discrete groundwater samples using direct push technology; (iii) case CPT locations, and (iv) complete installation of other geotechnical instruments in the same mobilisation.

  • Automatic rate control for steady probe advancement at 20 mm/s with up to 15 tons of static push.

  • Use any of Legion Drillings Geoprobe machines located in Brisbane, Sydney and Townsville.

TECHNICAL WEBINAR ON CPT

Ernst Wassenaar from Geomil presented this technical session on CPTu in May 2022. It is part of our series of webinars on advanced site characterisation and remediation.

FURTHER INFORMATION

Our field technicians will be happy to provide further information and discuss in detail any specific project requirements.

In the meantime, we recommend you consult the following documents: