An example plot of CPT data. Tip and friction sleeve resistance are plotted, followed by the ratio of the two. This is used to interpret soil behavior type on the far right, which ranges from clay to gravel. SPT N is calculated from the tip and friction sleeve resistance as a reference for those more familiar with Standard Penetration Tests.

Soil Behavior Type

Soil Behavior Type is based on the relationship between tip resistance and sleeve friction, where high tip resistance and low sleeve friction is generally indicative of larger grain sizes like sand and gravel. Clays and finer-grained materials are the opposite, generating high friction but low tip resistance. For more information on soil behavior type classification using CPT: Robertson, 2016