1. Laboratory of Foundation Engineering, Soil and Rock Mechanics, Bochum Ruhr Univ., DE (Corresponding author), e-mail: abelkhatir@yahoo.com
2. Laboratory of Materials Sciences and Environment, Hassiba Benbouali University of Chlef, DZ.
3. Laboratory of Foundation Engineering, Soil and Rock Mechanics, Bochum Ruhr Univ., DE.