1. Professor, Institute of Geotechnical Engineering, Technische Universität Dresden, D-01062 Dresden, Germany (corresponding author).
2. Research Assistant, Institute of Geotechnical Engineering, Technische Universität Dresden, D-01062 Dresden, Germany; on leave from Institute of Theoretical and Applied Mechanics AS CR, Prosecká 76, CZ-19000 Praha 9, Czech Republic.
3. Research Assistant, Institute of Geotechnical Engineering, Technische Universität Dresden, D-01062 Dresden, Germany.
4. Professor, Institute of Geotechnical and Tunnel Engineering, Univ. of Innsbruck, Techniker Str. 13, A-6020 Innsbruck, Austria.