1. Graduate Student, Dept. of Civil Engineering, K. U. Leuven, Kasteelpark Arenberg 40, B-3001 Leuven, Belgium.
2. Professor, Dept. of Civil Engineering, K. U. Leuven, Kasteelpark Arenberg 40, B-3001 Leuven, Belgium.
3. Postdoctoral Researcher, Dept. of Civil Engineering, K.U. Leuven, Kasteelpark Arenberg 40, B-3001 Leuven, Belgium.
4. Assistant Professor, Laboratory of Soil Mechanics, Ghent Univ., Technologiepark 9, B-9052 Zwijnaarde, Belgium.