Geotechnical characterization of the Aterno valley for site response analyses

Abstract

The paper reports about the in-situ and laboratory tests executed in the aftermath of the April 6, 2009 L’Aquila earthquake,
\naimed at contributing to the definition of geotechnical models for site response analyses in the Aterno valley. The investigation
\nstarted immediately after the earthquake and was entrusted by the Civil Protection Department to different public institutions
\nand private companies; the experimental activities here reported were coordinated by the Italian Geotechnical Society.
\nIn the paper, after briefly depicting the geological setting of the L’Aquila basin and the Aterno river valley, an overview of
\ntheir subsoil conditions is given, based on the geotechnical tests executed before the 2009 earthquake. Thereafter, the specific
\ninvestigations planned for the characterization of reconstruction sites and seismic microzonation are widely described. The in
\nsitu tests consisted of seismic dilatometer and multi-receiver surface wave tests; the resulting shear wave velocity profiles were
\ncompared each other, and against independent Down-Hole tests and ambient noise measurements. The laboratory investigation
\nincluded cyclic/dynamic simple/torsional shear tests on undisturbed samples. The results, summarized in terms of variation
\nof stiffness and damping with shear strain, highlighted some peculiar properties of the soils in the Aterno valley, which
\ncould be related to their index properties.