GNGTS 2014 - Atti del 33° Convegno Nazionale

Regione Emilia-Romagna; 2007: Atto di indirizzo e coordinamento tecnico ai sensi dell’art. 16, c. 1, della L. R. 20/2000 per “Indirizzi per gli studi di microzonazione sismica in Emilia-Romagna per la pianificazione territoriale e urbanistica” . Deliberazione dell’Assemblea Legislativa della Regione Emilia-Romagna n. 112 del 2/5/2007, Bollettino Ufficiale della Regione Emilia-Romagna n. 64 del 17/5/2007 Schnabel, P.B., Lysmer, J. and Seed, H.B.; 1972: SHAKE: a computer program for earthquake response analysis of horizontally layered sites . Report No. UCB/EERC-72/12, University of California, Berkeley, December, 102p. Engineering-geological and numerical modeling for the evaluation of the vibrational interaction between the city agglomerate and heterogeneous geological system: preliminary results C. Varone 1 , L. Lenti 2 , S. Martino 1 1 Department of Earth Sciences and Research Center for the Geological Risks (CERI), University «Sapienza», Rome, Italy 2 Université Paris-Est, Institut Français des Sciences et Technologies des Transports, de l’Aménagement et des Réseaux, Champs sur Marne, France Introduction. This paper is focused on the evaluation of the Site-City Interaction [SCI: Kham et al. (2006); Semblat et al. (2008)] due to the influence of buildings on the local seismic response and on the seismically-induced effects of alluvial fills. The study is part of a PhD research of the University of Rome “Sapienza”, which has been carrying on in co-operation with the IFSTTAR (Institut Français des Sciences et Technologies des Transports, de l’Aménagement et des Réseaux) of Paris. The Fosso di Vallerano valley (Rome, Italy) was selected as case study due to the fact that it is characterized by a highly heterogeneous geological setting and it is one of the most recent urbanized areas in Rome. More in particular, the Fosso di Vallerano valley hosts the “Europarco Business Park” i.e. the highest buildings (120 m) in Rome. Afirst phase of the study was focused on the reconstruction of the engineering-geological model of the valley through geological maps and cross-sections and a second phase is consisting in 2D numerical modeling of the seismic response in free field conditions as well as by considering the system city agglomerate according to a SCI approach. Some preliminary results of this research are here presented. Engineering-geological model. The Rome urban area is located in a peculiar geodynamic context on the Tyrrhenian Sea Margin, at the transition between northern and central Apennines, that results from combined glacio-eustatic, sedimentary, tectonic and volcanic processes from the Pliocene to present (Karner and Marra, 1998; Marra et al. , 2008; Milli et al. , 2008; Sottili et al. , 2010). To reconstruct the complex geological setting of the valley, 250 log stratigraphies from boreholes were considered as well as in-site geomechanical investigations, available from technical reports and official documents (Bozzano et al. , 2000; Ventriglia, 2002; Marra F. Personal database). Based on such data four main lithotechnical units were distinguished in the Fosso di Vallerano valley: - Plio-Pleistocene Marine deposits (Marne Vaticane Formation) composed by high consistency clays with silty-sandy levels; - Pleistocene alluvial deposits of the Paleo Tiber 4 River (650-600 ky) composed by soils including graves, sands and clays; - Volcanic deposits of the Alban Hills and of the Monti Sabatini Volcanic Districts (561-360 ky) consisting of highly heterogeneous tuffs; - Recent alluvial deposits that filled the valley incisions since the end of the Würmian regression (18 ky-Present), characterized by a basal gravel level and including by different soft soils from sands to inorganic or peaty clays. 294 GNGTS 2014 S essione 2.2