Early development of the Dutch cone penetrometer test

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 The device became known as the ‘mechanical CPT’ and has now been superseded by probes with the same basic dimensions but with loads and pressures measured locally using transducers.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