The cone penetration test (CPT) was developed in the Netherlands in the early 1930s as a deep-sounding apparatusthat measured cone resistance and was used to assess the distribution of alluvial soils and peat. It was developedfurther by increasing the push-down force to provide a method of designing piles. During the 1940s, improvementswere made by increasing the push-down force, also improving the probe geometry and test procedure. One of themost important developments of the CPT was made in Indonesia by Dutch engineers in the 1950s, who added thefriction sleeve used to measure local friction. The data from this device were used in an empirical design method todetermine the bearing capacity of friction piles. The device became known as the ‘mechanical CPT’ and has nowbeen superseded by probes with the same basic dimensions but with loads and pressures measured locally usingtransducers. The modern ‘electric CPT’ offers significant advantages; however, there are still places where themechanical CPT is used widely, such as in Indonesia. It should be appreciated that there can be significant differencesin the measured parameters, such that awareness of the type of probe being used is important, as are the methodsof interpretation.
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