CPTu NΔu cone factor for undrained shear strength of clays: A numerical study

Estimation of undrained shear strength (su) of a clayey soil from piezocone test (CPTu) can be achieved through a parameter known as the cone factor (N u) which relates s u to the measured excess pore-water pressure at cone shoulder (Δu2) such that su = u2/N u. In the present study, a finite element analysis of piezocone penetration test in saturated intact clays is carried out to attain a reliable solution for the cone factor, N u. The presented solution indicates that N u tends to decrease with soil OCR and to increase with rigidity index (Ir) of the soil. The new proposed equation is then compared with some existing solutions available in the literature for a relatively large database of field CPTu measurements. Based on the proposed equation, N u can practically range from 4.5 to 10, depending on the soil stiffness parameters.

کلیدواژه ها:

Undrained shear strength (su) ، Piezocone test (CPTu) ، Cone factor NΔu ، Excess pore-water pressure at cone shoulder (Δu2) ، Clayey soils.