Interrelationship between small strain modulus Go and operative modulus

This paper presents experimental diagrams constructed using same-depth values of the small strain modulus Go and of the working strain modulus (constrained modulus) M determined by seismic dilatometer (SDMT) at 34 different sites in a variety of soil types, in order to investigate the interrelationship between the two moduli. The ratio Go/M is plotted as a function of the DMT horizontal stress index Kd (stress history) and of the DMT material index Id (indicative of clay, silt or sand). Such experimental diagrams offer some elements of reply to the questions: (1) Is it feasible, as sometimes suggested, to estimate the operative modulus as Go divided by a constant? (2) Is it feasible, for a seismic classification, to use Su or Nspt as a substitute for Vs — when Vs has not been measured? Lines of research on the possible use of SDMT for deriving the in situ G-γ decay curves are also outlined.