Shear Modulus and Damping of Soils

The shear modulus (G) and damping ratio (D) of two natural clays and both siliceous and carbonatic pluvially-deposited dry sands have been measured at the authors' laboratory by means of a Resonant Column/Torsional Shear apparatus for a strain range of 0.0001% up to 1%. Different kinds of tests were performed on hollorr cylindrical specimens off all the: (a) monotonic load ing torsional shear tests at constant stress rate, (b) cyclic loading torsional shear tests at constant strain rate or at constant frequency and (c) Resonant Column tests. The results of the above tests enabled the authors to anallse the influence of strain level (g), loading rate (g'), number of loading cycles (N) and type of loading (monotonic or cyclic) on the measured values of G znd D.