1. Associate Professor, Faculty of Soil and Water Engineering, Univ. of Tehran, P.O. Box 4411, Karaj 31587-77871, Iran (corresponding author).
2. Postgraduate Student, Faculty of Soil and Water Engineering, Univ. of Tehran, P.O. Box 4411, Karaj 31587-77871, Iran.
3. Assistant Professor, Faculty of Agriculture Sciences and Engineering, Univ. of Tehran, P.O. Box 4411, Karaj 31587-77871, Iran.
4. Professor, Computational Geomechanics Group, Dept. of Engineering, Univ. of Exeter, Devon EX4 4QF, U.K.