GNGTS 2013 - Atti del 32° Convegno Nazionale

al. , 2008; Bindi et al. , 2009; Albarello and Lunedei, 2010). The use of the HVSR method as an exploration tool presents some typical limitations: where the ratio of the acoustic impedance among the explored soils is minor than 2 or where seismic noise around the point of measure is relevant is difficult to determine the f0 (SESAME European research project, 2004; Chatelain et al. , 2008, Guillier et al. , 2008). Furthermore, it is not possible to discriminate if the peak value obtained from the curve HVSR is due to the contact of the soft deposit with the seismic bedrock or with others layers with a high impedance contrast (e.g. ≥2). In order to overcome the HVSR uncertainties we proposed and tested a field methodology compatible whit the limited available budget of the L1 studies. We explored the benefits to make the HVSR measurement in-line to correlate the results of those. Geological features. The 4 investigated municipalities were: Perosa Argentina, Pinerolo, Sant’Antonino di Susa and Torre Pellice, located in Piemonte, northern Italy. In the following the main geological characteristics of the sites, due to the pre-existent investigations, as geophysical tests MASW, SEV, DH, penetrometric tests, bore-holes, etc. are presented. Perosa Argentina is characterized by the presence of: • gravel and sand with thickness among 10 and 80 m, the geotechnical parameters are: unit weight equal to 19-20 kN/mc, frictional angle equal to 35°-40° and cohesion equal to 0-5 kPa, the average value of the Vs is 350 m/s; • gravel with unit weight equal to 17-20 kN/mc, frictional angle equal to 30°-40° and cohesion equal to 0 kPa; • silt and clay; • the geological bedrock is, in the study area, marginally outcropping. The main geomorphological aspects are the presence of alluvial fans, slope debris, fluvial edges high between 10-20 m, a ridge and a man-made deposit. Pinerolo is characterized by the presence of: • gravel and sand with thickness among 10 and 60 m, the geotechnical parameters are: unit weight equal to 19-20 kN/mc, frictional angle equal to 40°-42° and cohesion equal to 0 kPa, the average value of Vs is 400-500 m/s; • silt and sand with unit weight equal to 18-19 kN/mc, frictional angle equal to 38°-40° and cohesion equal to 0-10 kPa; • the geological bedrock is, in the study area, marginally outcropping. The main geomorphological aspects are the presence of alluvial fans, fluvial edges and morphological scarps high among 10-20 m, the ridges, some landslides and a man-made deposit. Sant’Antonino di Susa is characterized by the presence of: • gravel and sand with thickness higher than 30 m, the average value of the standard penetration test is higher than 15 and the average value of the Vs is 250 m/s in the first 10 m and 400 m/s among 10-30 m; • sand and silt with thickness higher than 30 m, the average value of the standard penetration test is lower than 10 and the average value of the Vs is 250 m/s in the first 5 m, 350 m/s among 5-30 m and 400 m/s among 30-40 m • the geological bedrock is, in the study area, marginally outcropping. The main geomorphological aspects are the presence of alluvial fans and slope debris. Torre Pellice is characterized by the presence of: • alluvial deposit consisting of gravel and sand with thickness among 10 and 40 m, the geotechnical parameters are: unit weight equal to 19-20 kN/mc, frictional angle equal to 35°-40° and cohesion equal to 0-5 kPa, the average value of the Vs is 350-400 m/s; • ancient slope debris consisting of gravel and sand with unit weight equal to 17-19 kN/ mc, frictional angle equal to 25°-35° and cohesion equal to 0-5 kPa; • the geological bedrock is, in the study area, marginally outcropping. 481 GNGTS 2013 S essione 2.3