Correlation Coefficient K
The correlation coefficient of skin friction K is entered in the "Pile CPT" tab. The value of this coefficient is equal to the ratio of unit pile shaft resistance and unit penetrometer sleeve local friction. Correlation coefficient K can be expressed for example by the function of embedded pile length - see the following graphs.
Function of embedded pile length (D - embedded pile length, b - pile width or diameter)
FHWA HI 97-013: Design and Construction of Driven Pile Foundations, Workshop manual - Volume 1, National Highway institute.