1. 1 Department of Geotechnics, Faculty of Civil Engineering , University of Žilina , Univerzitná 8215/1, 010 26 Žilina , Slovakia .
2. 2 Department Civil Engineering, Faculty of Materials, Civil and Environmental Engineering , University of Bielsko-Biala , Willowa 2 43-309 Bielsko-Biała Poland .
3. 3 Dipartimento di Ingegneria e Architettura , University of Parma , Parco Area delle Scienze 181/a, 43124 Parma , Italy .