Andrea, hai considerato nella formula queste eccezioni:
-Robertson (2009) suggested that the normalized SBTn charts should be used with the normalized cone resistance (Qtn) calculated using a stress exponent that varies with soil type via Ic;
-the soil behavior type index does not apply to zones 1, 8 and 9;
-independent studies have shown that the normalized SBTn chart typically has greater than 80% (non 100%) reliability when compared with samples;
-Fr lo fornisci così: Fr = normalized friction ratio, in %
= (fs/(qt – svo)) x 100%?

The road not taken
(Robert Frost)