1. Associate Research Director, GeoEngineering Centre, Dept. of Civil Engineering, Queen's Univ., Kingston, ON, Canada K7L 3N6; formerly, Dept. of Civil and Environmental Engineering, Univ. of Western Ontario, London ON, Canada N6A 5B9 (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Western Ontario, London ON, Canada N6A 5B9.