ABSTRACT
A recent study (Han et al, 2019) showed that CPTs performed in sandy soils with a variable but sometimes significant gravel content, despite special operational measures (alternating drilling and CPT), frequently provide unrealistic qc values which adversely affect the piles capacity predictions even using the most representative CPT-based design methods. However a series of SPT verticals are also available and the conversion of N30 into qc values has allowed, via a number of steps, the development of four virtual CPTu, two of which were then used for the pile capacity predictions This procedure has proven to be effective, so that, even employing far less authoritative methods, were obtained sufficiently approximate shaft and toe resistances.
