Editing Cone penetration test (section)

{{Short description|Method used to determine the geotechnical engineering properties of soils}}
[[Image:cpttruck.jpg|right|thumb|250px|A CPT truck operated by the [[USGS]].]]
[[File:Cone penetration test.svg|thumb|100px|Symbol used in drawings]]
[[File:Cone penetrometer.svg|right|thumb|Simplified version of a cone penetrometer.]]
The '''cone penetration''' or '''cone penetrometer test''' ('''CPT''') is a method used to determine the [[geotechnical engineering]] properties of [[Soil mechanics|soil]]s and delineating soil [[stratigraphy]]. It was initially developed in the 1950s at the Dutch Laboratory for Soil Mechanics in [[Delft]] to investigate soft soils. Based on this history it has also been called the "Dutch cone test". Today, the CPT is one of the most used and accepted soil methods for [[geotechnical investigation|soil investigation]] worldwide.

The test method consists of pushing an instrumented [[cone]], with the tip facing down, into the ground at a controlled rate (controlled between 1.5 -2.5&nbsp;cm/s accepted). 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&nbsp;cm<sup>2</sup>, corresponding to diameters of 3.6 and 4.4&nbsp;cm. A very early ultra-miniature 1&nbsp;cm<sup>2</sup> 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.