CPT and CPTu data for soil profile interpretation: review of methods and a proposed new approach



Cone penetration test (CPT) allows for the soil type to be determined from the measured values of cone resistance (qt) and sleeve friction (fs). Since the cone penetrometer progressed from the mechanical cone to the electrical piezocone (CPTu), the reliability of the determination of soil type also improved by pore pressure (u) measurement. This paper references several published methods of soil profiling. All but two of these apply cone resistance plotted against the friction ratio (Rf). A new method for soil profiling has been developed by plotting effective cone resistance (qE) versus sleeve friction with a compiled database from 20 sites in 5 countries. This paper presents two soil profiling methods based on the piezocone and compares them with three specific cases containing sand, normally consolidated clay and overconsolidated clay. Both methods result in an accurate soil type determination.