1. Assistant Professor of Geotechnical Engineering, Dept. of Structural Engineering, Politecnico di Milano, p.za L. da Vinci, 32, 20133 Milan, Italy (corresponding author).
2. Professor of Geotechnical Engineering, Dept. of Structural Engineering, Politecnico di Milano, p.za L. da Vinci, 32, 20133 Milan, Italy.
3. Geologist, Studio Associato di Geologia Spada, via Donizetti 17, 24022 Ranica (BG), Italy.