GNGTS 2013 - Atti del 32° Convegno Nazionale

Basilica (about fourteen shallow boreholes and a well of 70 m depth), and for the Basilica itself (a couple of verticals), as shown by MS–AQ Working Group (2010). In addition the deep boreholes in the historical centre promoted by the University of L’Aquila – Centre for Research and Education in Earthquake Engineering (CERFIS) (Amoroso et al. , 2010; Cardarelli e Cercato, 2010), the seismic microzonation study (MS–AQWorking Group, 2010) and the further investigations carried out for the reconstruction of private damaged buildings (Amoroso et al. , 2014), together with numerous studies already realized in L’Aquila basin (Monaco et al. , 2012, 2013; Santucci de Magistris et al. , 2013; Milana et al. , 2011), allowed to develop a detailed geological, geotechnical and geophysical model. In addition, Eni provided funds for three deep boreholes (80 m, 120 m and 270 m depth) and several shallow ones together with geotechnical and geophysical investigations (seismic dilatometer tests, cyclic laboratory tests, seismic noise measurements, MASW and seismic refraction surveys), still ongoing (AA.VV ., 2013), for the Basilica seismic reinforcement and rebuilding project. Geological and geotechnical characterization. Geological setting. The Santa Maria di Collemaggio Basilica is located just outside in the south eastern part of the medieval walls of L’Aquila city centre. It is placed in a flat terraced hill whose schematic geological setting consists, from the top to the bottom, of a middle Pleistocene 100 m-thick variably-cemented calcareous breccias (L’Aquila breccias Auct.) which lay onto a 200 m-thick homogeneous lower Pleistocene-upper Pliocene (?) fluvial-lacustrine pelite and sand. In their turn, they are placed onto the deep Meso-Cenozoic carbonate bedrock which its depth decreases toward NE (Amoroso et al. , 2010; Del Monaco et al. , 2013; MS–AQ Working Group, 2010; Tallini et al. , 2011). L’Aquila breccias thickness decreases from about 100 m in the central sector of L’Aquila city centre (at the Market square) to 0-10 m in the southern slope of L’Aquila hill where they are laterally replaced by sand and pelite and calcareous gravels and breccia layers (Del Monaco et al. , 2013). In the Basilica area, the soundings, carried out by Eni (AA.VV ., 2013), improved the fine scale subsoil model. Here, L’Aquila breccias have a thickness of about 44 m and the boundary between them and the underlying sand and pelite is nearly horizontal. Further a few meters of fine-grained soils (red soils) are locally arranged into or onto them. Geotechnical model. The geotechnical model, used for these preliminary numerical analyses, was based on the geological, geotechnical and geophysical investigations already Fig. 1 – Geotechnical model used for 1D and 2D seismic response analyses. 173 GNGTS 2013 S essione 2.2