SDMT VS profiles in heterogeneous granular soil deposits

Abstract

Many urbanized areas of the Apennines, in Italy, have complex soil stratifications. A typical example is the historical center of L'Aquila and its outskirts, founded on layers of significantly heterogeneity and struck by a strong earthquake in 2009. Under these conditions, shear wave velocity profiles (VS) obtained from in-situ measurements using SDMT techniques allow reliable analyses of local seismic response. In the soil of L'Aquila, the use of SDMT tests in sand-filled boreholes, following the procedure described by Totani et al. (2009), allowed VS to be measured at considerable depths. This article presents the results of local seismic response analyses conducted to characterize the soil foundation of the hospital complex and adjacent university buildings in L’Aquila before their seismic retrofitting. The authors developed a soil model based on the Vs profiles retrieved from the SDMT tests. This approach provided a detailed understanding of the soil seismic behaviour, essential for the proper characterization of seismic action and consequently, the design of seismic interventions. The study emphasises the importance of accurate soil characterisation prior to seismic upgrades especially in deposits where there are multiple shear wave velocity inversions. The seismic demand coming from the Italian Building Code of 2018, based on the so-called soil categories from equivalent velocity of shear wave, was compared to the results of the local seismic response analysis conducted by using the real Vs profiles from SDMT, which are extended to a much greater depths than those generally required by the regulations.

Full Paper