Cone penetration test

A very early ultra-miniature 1 cm2 subtraction penetrometer was developed and used on a US mobile ballistic missile launch system (MGM-134 Midgetman) soil/structure design program in 1984 at the Earth Technology Corporation of Long Beach, California.

The early applications of CPT mainly determined the logistics of soil geotechnical property of bearing capacity.

The original cone penetrometers involved simple mechanical measurements of the total penetration resistance to pushing a tool with a conical tip into the soil.

Pore water pressure data aids determining stratigraphy and is primarily used to correct tip friction values for those effects.

CPT and CPTU testing equipment generally advances the cone using hydraulic rams mounted on either a heavily ballasted vehicle or using screwed-in anchors as a counter-force.

An additional CPT deployed tool used in Britain, Netherlands, Germany, Belgium and France is a piezocone combined with a tri-axial magnetometer.