1. 1 Department of Geotechnics, Faculty of Civil Engineering , University of Zilina , Univerzitna 8215, 010 26 Žilina , Slovak Republic .
2. 2 Institute of Geotechnics, Faculty of Civil Engineering , Brno University of Technology , Brno , Czech Republic .
3. 3 Geart, s.r.o. P. O. Hviezdoslava 42A , Žilina , Slovak Republic .