Dynamic analyses of geotechnical problems using advanced constitutive formulations: soil parameter calibration and numerical implementation

The doctoral research has focused on an accurate study of granular soil behaviour in static and seismic conditions, with special reference to seismic-induced phenomena such as liquefaction and lateral spreading whose evidences have been observed during the 2012 Emilia earthquake. The basic aim of the study has been to develop an innovative numerical tool for reproducing the mechanical response of silty-sand soils under different loading and drainage conditions adopting an advanced constitutive model, which could be calibrated from tests that are routinely performed in geotechnical laboratory. Thus, an experimental testing programme, including triaxial tests, standard and K0-cell oedometer tests, has been carried out on a number of sandy and silty samples extracted from the subsoil of Scortichino (Emilia-Romagna, Northern Italy), a village struck by the 2012 seismic sequence. Therefore, the experimental results have been interpreted taking a Generalized Plasticity-based model for sands as reference constitutive framework. In particular, starting from the existing formulation devised by Pastor et al. (1990) and later extended by Tonni et al. (2006) and Cola et al. (2008), a few modifications have been introduced to the original constitutive equations in order to improve the predictive capability. An in-depth calibration study has been performed and an effective procedure to obtain the model parameters has been defined. For this purpose, a MATLAB numerical routine has been developed. Finally, the constitutive equations have been implemented in a 2D FE code (GeHoMADRID) and a detailed numerical model of the riverbank has been realized in order to perform advanced dynamic analyses and to study both the stress-strain behaviour and the seismic-induced effects within the investigated granular deposits during the 2012 Emilia earthquake.