1. Geotechnical Engineer, Parsons Brinckerhoff Inc., 2777 N Stemmons Freeway, Suite 1333, Dallas, TX 75207 (corresponding author).
2. Professor, Dept. of Mining and Materials Engineering, McGill Univ., 3450 University St., Montreal, PQ, Canada H3A 2A7. E-mail: Hani.Mitri@McGill.Ca