Dynamic Clay Soils Behaviour by Different Laboratory and in Situ Tests

Since the eastern Sicily has been struck by various disastrous earthquakes with a MKS intensity from IX to XI in the last 900 years, an investigation program was performed in different test sites to evaluate the dynamic clayey soils behaviour. The following dynamic investigations in the laboratory were carried out on undisturbed samples: Resonant Column Tests (RCT), Cyclic Loading Torsional Shear Tests (CLTST) and Cyclic Loading Triaxial Tests (CLTxT). The influence of the type of tests, of the strain rate and of the number of loading cycles on G-g and D-g curves, as well as on pore pressure build-up, was evaluated by means of laboratory tests. Moreover in situ investigations were carried out in order to determine the soil profile and the geotechnical characteristics for the site under consideration. Borings, Standard Penetration Test (SPT), Cone Penetration Test (CPT), Down Hole (DH) Tests and new Seismic Marchetti Dilatometer Tests (SDMT) were performed. The available data enabled one to obtain a comparison between the small strain shear modulus (DH, SDMT and laboratory tests) for the specific site. It was also possible to compare in situ and laboratory small strain shear and the G-g curve for soil non-linearity evaluation..